DESIGN RATIONALE CAPTURING MODEL FOR USE DURING THE EMBODIMENT PHASE OF THE PRODUCT DESIGN

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1 Danel Rohde Maro Štorga Doran Maranovć ISSN eissn DESIGN RATIONALE CAPTURING MODEL FOR USE DURING THE EMBODIMENT PHASE OF THE PRODUCT DESIGN Summary An analyss of a desgn ratonale focusng on the embodment desgn stage s presented through the characterzaton of nformaton descrbng desgn problems, alternatve solutons, arguments, explanatons and decsons of desgners. The characterzaton of the desgn questons resulted from emprcal research. The fndngs have been used to descrbe n detal elements of a desgn ratonale capturng model. The man attrbutes descrbe ths model durng the embodment phase of the product desgn, possble relatons between the desgn ratonale elements and the defnton rules. Key words: knowledge management, ssue, desgn problem, alternatve soluton, argument, decson, desgn ratonale 1. Introducton Nowadays, t s easy to notce changes n the global market whch dramatcally nfluence ndustral companes. The tradtonal understandng of how the companes vew ther product and the product s role n ther busness model s currently beng reworked. Desgn cycles are becomng faster and pressure to save tme and reduce costs s exerted from large corporatons down to small enterprses confronted wth tough rules n order to survve on the market. It s known that the most mportant factors behnd the company s success are loyal employees and the reuse of prevously acqured knowledge. Unlke the tmes when people worked almost ther entre lves n the same company at the same workplace, today's tendency s that people frequently change obs, both nsde and outsde of the company. Such rapd changes result n a lack of tme for employees to gan expertse n dfferent, specalzed areas of ther actvty. As these employees (mechancal engneers) begn to retre, they take wth them ther vast knowledge, whch can be seen as another problem for the company. The desgn process has a sgnfcant mpact on costs n product development [1]. For ths reason, the pressure to save tme and money leads to the acceleraton of the product development cycles. In ths stuaton, new employees do not have enough tme to gan experence n desgnng new products n the doman of the company. Lack of knowledge related to the desgn ratonale [2] can be a bg step back and results n the prolongaton of the desgn actvtes. TRANSACTIONS OF FAMENA XXXIX-1 (2015) 27

2 D. Rohde, M. Štorga, D. Maranovć Desgn Ratonale Capturng Model for Use durng the Embodment Phase of the Product Desgn The prmary am of the research presented n ths paper s the development of a desgn ratonale capturng model that could be utlsed durng the embodment phase of the product desgn. The research approach that s presented n ths paper encompasses the results obtaned from the developed classfcaton of explanatons and arguments related to the correspondng desgn problem solutons and decsons that could be used n the conceptual, embodment and detal desgn stages as a part of complex and long-term desgn proects. The motvaton for the presented research orgnates from challenges that are common to engneerng desgn departments n small and medum szed companes. Desgnng as a concept s used extensvely n varous dscplnes, but understandng of the concept s not unque. Accordng to Burge, the desgn process conssts of a set of steps or actons that have to be taken to acheve the purpose of the product [2]. In ths process, desgners make decsons that are based on dfferent reasons and arguments (such as economc, technologcal, tme, or experence.). An mproved process and a better fnal desgn can be acheved through the effcent and effectve utlsaton of nformaton and knowledge resources for engneerng desgn [3]. In the product development process, t s crucal to understand prevously consdered desgn solutons n order to redesgn the exstng product, adapt these solutons to desgn a new product and/or evaluate new desgn solutons. Knowledge management s one of the crtcal ssues for the company, and there s a need for capturng, storng and reusng knowledge [4]. The structure of the paper s as follows. Secton 2 gves a bref overvew of the concept "desgn ratonale" and ts value for desgners. Secton 3 reports on the approach adopted for ths research, and n Secton 4, on the results of the emprcal study. In Secton 5, a desgn ratonale capturng model s presented followed by an evaluaton n Secton 6. The fnal secton dscusses the mplcatons and conclusons. 2. Background and related work Lterature revew shows that durng the development process, desgners sometmes spend more than 50% of ther tme manpulatng nformaton. Also, over 50% of the nformaton requred for the realzaton of the product development s unavalable or unknown at the begnnng of the process [3]. Desgners typcally spend 20-30% of ther workng tme searchng for and retrevng nformaton [5]. For ths reason, the effcency of the desgn process and product qualty s very dependent of the access to nformaton and the ablty to use large amounts of nformaton [3]. For mprovng an exstng product and developng a new product, the ablty of desgners to nterpret past desgn solutons and decsons that such prevous desgn solutons mply s crucal. Techncal descrpton of a product, recorded n formal documents such as reports, techncal drawngs, and 3D models, descrbes results of the development process but not the development process and the decson-makng process themselves. Especally, there are no records on decsons and arguments that are based on experence. Ths problem leads to a loss of knowledge ganed whle solvng desgn problems. In lterature, ths knd of knowledge s called desgn ratonale. Desgn ratonale ncludes the reasons behnd a desgn decson, the ustfcaton for a desgn decson, other consdered alternatves, evaluated tradeoffs and argumentaton that led to a decson [6]. In general, the systems proposed n the lterature for capturng, storng and reusng nformaton and knowledge (desgn ratonale) can be dvded nto: (1) the systems whch requre nvolvement of desgners durng the capturng of nformaton; and (2) the systems where ths procedure s more or less automated by the use of artfcal ntellgence [7], [8]. Automated systems are applcable only when development tasks are prevously known. For example, ths occurs durng the detaled desgn phase especally n the development of varant 28 TRANSACTIONS OF FAMENA XXXIX-1 (2015)

3 Desgn Ratonale Capturng Model for Use durng the Embodment Phase of the Product Desgn D. Rohde, M. Štorga, D. Maranovć products. Systems that requre an nvolvement of desgners n the capturng of nformaton and knowledge shall apply durng all stages of the development of new products or new functonaltes of exstng products. In both cases, f the employee would lke to capture "nformal" nformaton and knowledge t s necessary to nclude desgners n the knowledge capturng process. Hu et al. [9] present a revew of desgn ratonale systems and representaton languages proposed by dfferent authors up to They found that the most common argument structures for selectng and organzng nformaton are IBIS, PHI, QOC and DRL: 1. IBIS (Issue Based Informaton System) [6]: ssue, postons, arguments 2. PHI (Procedural Herarchy of Issues) [10]: ssue, answers, arguments 3. QOC (Queston, Opton and Crtera) [11]: queston, optons, crtera 4. DRL (Decson Ratonale Language) [12]: ssue, alternatves, goals Despte over 30 years of research, there are stll few ratonale systems used n practce [13]. There s a strong consensus that ratonale s valuable, but there s an equally strong concern that the costs of ts capture may be too hgh. In order to ustfy the costs of ts capture, t s essental to establsh ways n whch ratonale can be useful that exceed a smple provson of addtonal desgn documentaton [13]. Desgn ratonale capturng tools are begnnng to be accepted n the ndustry, e.g. the Desgn Ratonale edtor (DRed) developed by Engneerng Desgn Centre (EDC) of Cambrdge Unversty [14]. Prelmnary research on the DRed usage n practce shows that structured nformaton s easer to nterpret than tradtonal desgn defnton reports [15]. DRed s a graphcal software tool for acqurng knowledge n the early stages of the desgn process and solvng the problems that occur durng the product servcng. As a startng pont of our research the prevously mentoned DRed and Compendum have been used [16]. The avalable lterature shows that there s an unexplored area of the knowledge management, specfcally relatng to the classfcaton of desgn problems, explanatons regardng alternatves and arguments that lead to desgn decsons. 2.1 Desgn reasonng process By descrbng relatonshps between data, nformaton and knowledge the authors [17] summarzed that n the feld of engneerng desgn there exst two aspects of knowledge producton: (1) knowledge processes generated by an ndvdual through the understandng, assmlaton and applcaton of nformaton and other knowledge elements; and (2) knowledge elements produced by the learnng processes. As well as other humans, desgners nfer new knowledge elements from nformaton, other knowledge elements or a combnaton of all. Roozenburg and Eekels call ths nferrng process reasonng. Reasonng can be defned as a cogntve process of searchng for reasons for own belefs, conclusons, actons or feelngs [18]. The result of the desgn process s a techncal product. Durng that process, dfferent knds of nformaton are appearng. By analyzng data collected durng the development proects nvolved n ths study t was observed that the collected nformaton can be grouped nto: 1. nformaton about proects, people nvolved and product development stages 2. nformaton that represent the content of the desgn reasonng 3. nformaton about how to retreve nformaton captured durng prevous desgn reasonng processes (nformaton that concern storng, accessng and searchng) In lne wth the research goal the focus n ths chapter s on nformaton that forms the desgn reasonng content. There was observed the exstence of formal and nformal type of nformaton whch can be grouped nto: TRANSACTIONS OF FAMENA XXXIX-1 (2015) 29

4 D. Rohde, M. Štorga, D. Maranovć Desgn Ratonale Capturng Model for Use durng the Embodment Phase of the Product Desgn 1. nformaton that affects decsons n the desgn process related to the obectves and requrements defned n any of the product development stages 2. nformaton that descrbes (explans) decsons n the desgn process descrptons of problems, alternatves and arguments used for the evaluaton of alternatves 3. nformaton about the desgn artefact product, components, assembly, assembly connectons and constrants 3. Research methodology Followng the Desgn Research Methodology [19], stages and the man outcomes of the research are presented [Fg. 1]. Basc means Stages Man outcomes Introducng the research area through lterature analyss Research motvaton and ams Background and related work Obectves, strategy and lmts to the research Ethnographc partcpaton Intervewng desgners Emprcal data analyss Emprcal research Insghts n the feld, clear defnton of the research ams Detaled analyss of the nformaton collected durng the development proect of the chamber for delectrc spectroscopy of aqueous solutons The desgn ratonale capturng model Desgn ratonale elements, attrbutes of the DR elements, the logcal bass for the DR capturng model Evaluaton approach descrpton Expermental data analyss Evaluaton of the DR capturng model Concluson Descrpton of partcpants, experment setup, techncal reports, questons, expermental data collecton Implcatons for the work Fg. 1 The structure of the research methodology Durng the lterature revew not enough evdence to clearly determne all aspects related to resolvng desgn problems durng the embodment desgn stage was found, so authors decded to observe and ntervew desgners at work to obtan a better understandng of the research ssues. The desgn ratonale analyss showed the complexty of questons nvolved n knowledge capturng durng the embodment desgn phase. The study was conducted wth an emphass on solvng desgn problems. The results of the analyss are dstnctve attrbutes of the desgn ratonale (DR) elements: (1) problem, (2) alternatve, (3) argument, (4) explanaton and (5) decson. Descrpton of the attrbutes, possble connecton rules between the DR elements and the defnton rules for the DR elements are the bass of the proposed desgn ratonale capturng model for use durng the embodment phase of the product desgn. A detaled analyss of the proposed model n a real product development process s done only partally by conductng an experment and analysng the data collected durng the experment. 30 TRANSACTIONS OF FAMENA XXXIX-1 (2015)

5 Desgn Ratonale Capturng Model for Use durng the Embodment Phase of the Product Desgn D. Rohde, M. Štorga, D. Maranovć 4. Emprcal study The goal of the emprcal study was to answer the followng research queston: 1. What knd of data, nformaton and knowledge should be captured (consderng the needs of companes n the observed doman)? Snce the answer to that research queston requred drect and ndrect observaton of desgners durng the product developng process, t was necessary to take the followng nto account: tme that the respondents (desgners) can be avalable for dscusson wth the researcher. confdentalty of nformaton obtaned from the observaton and dscusson wth the desgners. Ths phase of research s dvded nto three subphases: 1. Ethnographc research 2. Intervewng desgners 3. Data analyss A beneft of the nvestgaton conducted n ndustry s that the researcher s nvolved n the socal and techncal context and has an opportunty to get to know the rest of the team [20]. It has been observed that deal case s when the researcher s level of knowledge s close to the level of the knowledge of professonal desgners. For these reasons, the researcher has spent some tme (18 months) workng on one of the current proects of the assocate company. The ethnographc research was conducted through the actve partcpaton of the researcher n solvng desgn problems durng the development process of a backpack sprayer and duster unt for agrcultural usage. Ths knd of actve partcpaton enabled us to collect data n a neutral atmosphere. We had assumed that t would help us to reduce bas regardng the behavour of partcpants because they knew they were partcpants n an experment. Durng the proect the researcher recorded hs decsons, contacts, calculatons, drawngs, presentatons, CAD models, sketches and tme spent on each desgn task n a log-book. Intervews wth other desgners were conducted to obtan: (1) relevant nformaton about the desgn process that was mplemented n the company and (2) desgners opnons about the types of nformaton and knowledge that should be collected for use n future proects. The collected data were subsequently analyzed, and the results were used n the next phase of the study. Because desgners defne desgn problems n the form of questons, there was a possblty of applyng research results from the scentfc lterature. So, n the experment we decded to use Aursccho's taxonomy of knowledge requests (questons to whch desgners are lookng for answers) [20]. Aursccho has proposed a codng scheme for hs taxonomy n whch each element of the taxonomy s ndexed wth two dgt code. One partcular request s charactersed (ndexed) wth an approprate combnaton of tems from each group of categores e.g. D2-E1-F1-G5-H7-I5 (Obectve - Subect - Response process - Response type - Drecton of reasonng - Behavour type). The applcablty of Aursccho s codng scheme has already been nvestgated [21]. We started to apply such a codng scheme to a subset of knowledge requests that were generated n the development process of the backpack sprayer and duster unt for agrcultural usage. From the log-book, wrtten durng the ethnographc research, we extracted 120 knowledge requests concernng the development of the dosage handle subassembly. Each knowledge request was further descrbed as the followng set of recorded attrbutes: am, nformaton source, meda, start/end date, outcome and comments. Each knowledge request beng treated as a class of a knowledge element (chunk) had n addton a set of hyperlnks to relevant documents and CAD fles. The next phase of the experment ncluded the generaton of codes for each knowledge request recorded n the database [21]. TRANSACTIONS OF FAMENA XXXIX-1 (2015) 31

6 D. Rohde, M. Štorga, D. Maranovć Desgn Ratonale Capturng Model for Use durng the Embodment Phase of the Product Desgn In the process of codng, for some requests t was not always easy to decde whch subcategory the request should belong to. For ths reason, we tested the repeatablty of the generated codes. One week after the frst codng, the codng process was repeated on the whole record set of knowledge requests. The code comparson showed that for only 40% of requests an entrely the same dentcal code was made n both attempts. Then, we compared only the frst four categores (D-E-F-G), whch showed that there were 68.33% of knowledge requests wth the same code. In the end, we compared the combnaton of three categores (D- E-F; D-E-G; D-F-G and E-F-G), and the results showed that there were 100 (83.33%) of knowledge requests wth the same code. As a result of ths analyss, we notced a need for further nvestgaton of nformaton requests to select those classes that would ensure unambguous categorzaton. It was also necessary to explore other desgn ratonale elements durng the embodment desgn phase. 5. The desgn ratonale capturng model The lterature does not often show a clear dfference between the problem-solvng process and the task solvng process. Problem-solvng can be assocated wth the case when n the begnnng of the process the methodology s not known. So, f the solvng methodology s not known n advance, t could be sad that the desgner resolves the desgn problem, otherwse the desgner resolves the desgn task. Also, t s mportant to emphasze the domnance of the ntutve and creatve thnkng (durng the desgn problem-solvng process) that s very dffcult to formalze. We assume that only the desgners who are responsble for the problem resolvng can descrbe DR elements, and they should be ncluded n the nformaton capturng process. To help desgners to defne DR elements and connectons/lnks between the DR elements t s necessary to propose attrbutes and ther possble values. The desgn ratonale capturng model [22] s descrbed by prmary attrbutes and possble relatons between the desgn ratonale elements. These elements are brefly explaned below and n the followng chapters. The basc types of Desgn Ratonale Scheme ( DRS ) elements are: (1) problem ( P ); (2) alternatve ( S ); (3) argument ( A ); (4) explanaton ( E ); and (5) decson ( D ), [Fg. 2]. A Desgn Ratonale Scheme ( DRS ) conssts of a fnte set of basc elements lnked wth drected arrows. It necessarly contans only one problem P for whch t s necessary to defne all attrbutes. Essental attrbutes whch descrbe the problem are: (1) Type; (2) Queston; (3) Queston goal; (4) Problem descrpton; (5) Cause of the problem; (6) Subect; (7) Drecton of reasonng; and (8) Status. For a problem P there can be proposed a fnte set of alternatves S S 1 S2... S u. The set S can be an empty set S, whch means that for the defned P no alternatve s proposed. For alternatves, S t s necessary to defne all of ther attrbutes. Essental attrbutes that descrbe the alternatve are: (1) Type; (2) Source; (3) Representaton; (4) Descrpton; (5) Usefulness; and (6) Status. All defned alternatves S need to be lnked to the problem P. The lnk between the alternatve and the problem contans one of the attrbute values of the alternatve named usefulness: (1) unsatsfactory alternatve; (2) ust about acceptable alternatve; (3) satsfactory alternatve; (4) good alternatve; and (5) very good alternatve. Values, that an attrbute named usefulness can take, depend on the evaluaton range that s used n the company. Here, the assessment accordng to the gudelne VDI 2225 [23] s used. Evaluaton and assessment are not the focus of ths paper, but the dentfcaton of the attrbutes that descrbe the alternatves s. 32 TRANSACTIONS OF FAMENA XXXIX-1 (2015)

7 Desgn Ratonale Capturng Model for Use durng the Embodment Phase of the Product Desgn D. Rohde, M. Štorga, D. Maranovć unsatsfactory alternatve / ust about acceptable alternatve / satsfactory alternatve / good alternatve / very good alternatve DESIGN RATIONALE SCHEME Problem Type Queston Queston goal Problem descrpton Cause of the problem Subect Drecton of reasonng Status undefned / solved / not solved proceed / not solved reect / not solved unsolvable Alternatve Type Source Representaton Descrpton Usefulness Status analyzes / evaluates / has an mpact /... analyzes / evaluates /... Explanaton Type Queston Drecton of reasonng Subect Answer Status analyzes / evaluates / has an mpact /... Decson Type Reason Descrpton Status actve / accepted / reected supports / does not support analyzes / evaluates /... Argument Type Group Descrpton Influence on decson Status has an mpact / does not have an mpact Legend: The relatonshp between the elements Desgn ratonale element Fg. 2 Desgn ratonale capturng model Wth every defned alternatve Su S a fnte set of arguments can be proposed: Ak A l, where A l A 1 A2... A s s a set of all proposed arguments n one DRS. Set A k can be an empty set A k, whch means that for a proposed alternatve Su S no argument s proposed. Set A l can also be an empty set A l, whch means that for the proposed alternatves S no argument s proposed. If A l s vald, then A k s vald too snce Ak Al. For arguments, A k t s necessary to defne all ther attrbutes. Basc attrbutes that descrbe an argument are: (1) Type; (2) Group; (3) Descrpton; (4) Influence on decson; and (5) Status. There s a need to lnk all of the defned arguments A k wth the alternatve Su S. The lnk between the argument and the alternatve contans one of the attrbute values of the Argument type: (1) supports an alternatve, or (2) does not support an alternatve. An argument As Al can be lnked wth more alternatves from the set S. In ths way, the attrbutes that descrbe the argument are not changed except the Argument type that s an ntegral part of the lnk. A problem P s necessarly lnked wth only one decson D, for whch t s necessary to defne all of ts attrbutes. Basc attrbutes that descrbe a decson are: (1) Type; (2) Reason; (3) Descrpton; and (4) Status. The table shows changes n ndvdual attrbutes values of the problem and the decson from the ntal state to the fnal state [Table 1]. TRANSACTIONS OF FAMENA XXXIX-1 (2015) 33

8 D. Rohde, M. Štorga, D. Maranovć Desgn Ratonale Capturng Model for Use durng the Embodment Phase of the Product Desgn Table 1 Possble change n ndvdual attrbutes values of the problem and the decson Case Decson type Decson Decson dentfcaton Problem status (, N) status ntally Undefned Actve D Actve 1 A Proceed Accepted D Actve 2 fnally Solved Accepted D Solved B ntally Undefned Actve D Actve 1 fnally Solved Accepted D Solved C ntally Undefned Actve D Actve 1 fnally Not solved reect Accepted D Reected D ntally Undefned Actve D Actve 1 fnally Unsolvable Accepted D Unsolvable ntally Solved or Solved or Proceed or 1 Accepted D Actve or Not solved reect Reected E 2 Undefned Reected D Actve 3 Undefned Actve D Actve fnally Solved or Not solved proceed or Not solved reect Accepted 4 D Solved or Actve or Reected Problem dentfcaton (, N) P 1 P 2 P P 1 P P 1 P P 1 P 1 P 2 P 3 P 4 P The decson D s lnked to the problem P. The lnk between the decson and the ssue contans one of the attrbute values of the Decson type: (1) undefned; (2) solved; (3) not solved proceed; (4) not solved reect; and (5) not solved unsolvable (there exst strong arguments n the desgner s pont of vew that the problem s unsolvable, at least at that pont of tme. Arguments from the set A l are lnked to the decson D. The lnk between the argument and the decson contans one of the attrbute values of the Impact on decson: (1) has an mpact, or (2) does not have an mpact. The decson D s lnked to the alternatves S. The lnk between the decson and the alternatve contans one of the attrbute values of the Alternatve status: (1) actve; (2) accepted, or (3) reected. One DRS can nclude a fnte set of explanatons E m E 1 E2... E r, for whch t s necessary to defne all of ther attrbutes. Basc attrbutes whch descrbe the explanaton are: (1) Type; (2) Queston; (3) Drecton of reasonng (4) Subect; (5) Answer; and (6) Status. The set E m can be an empty set E m, whch means that for the proposed DRS no explanaton s proposed. All proposed explanatons E m are necessarly lnked to at least one element as a part of DRS (problem, alternatve, argument, explanaton, decson). The lnk between the explanaton and other DR elements can have the followng values: (1) s a qualtatve fact; (2) s a quanttatve fact; (3) analyzes; (4) evaluates; and (5) has an mpact on the decson. All proposed DR elements as a part of DRS can be lnked wth the fnte set of the IO IO IO... [24]. The lnk can have a value: s Informaton obects n 1 2 IO p 34 TRANSACTIONS OF FAMENA XXXIX-1 (2015)

9 Desgn Ratonale Capturng Model for Use durng the Embodment Phase of the Product Desgn D. Rohde, M. Štorga, D. Maranovć connected. One IO p can be lnked wth one or more DR elements that are part of the fnte set DRS o DRS1 DRS2... DRS. The DR element (problem, alternatve, argument, explanaton, decson) can be deleted only when DRS and P are n the actve status. The status and dentfcaton of DRS are the same as the status and dentfcaton of P. There s a possblty to connect two or more Desgn Ratonale Schemes whch are part DRS DRS DRS... to each other. For example the proposed of the fnte set DR elements that are a part of o 1 2 DRS DRS can be lnked wth DR elements as a part of DR 1. The model should be flexble, whch mples the possblty of addng new values for DR element s attrbutes. 6. Evaluaton of the DR capturng model 6.1 Evaluaton approach Expermental evaluaton was carred out by two groups of students (who were n the fnal year of the engneerng desgn study programme, product development proect related course). Each group conssted of fve ntervewees who read and nterpreted techncal reports wth the purpose to fnd answers to predefned questons. The authors prepared questons and techncal reports n order to determne how the defned DR elements and ther attrbutes affect: the understandng of nformaton of the product and product development; the nformaton searchng process. The experment was desgned to smulate the real workng stuaton n whch desgners retreve nformaton and knowledge captured durng prevous product development proects. It s mportant to emphasze that the partcpants (ntervewees) had no prevous contact wth any nformaton related to the proect used n the preparaton of techncal reports for the experment. In ths way, authors wanted to elmnate the nfluence of past experence and knowledge of the expermental results. The experment conssted of four maor steps [Table 2]. At the begnnng of each queston, ntervewees had a specfed amount of tme (30 mnutes for each group of questons) for readng, nterpretng and understandng (the test experment wth another group of students had been carred out n advance n order to determne the tme requred to answer the questons). After that, they read and nterpreted the nformaton from the predefned techncal report. In the thrd step, they retreved nformaton from the report and wrote ther answers n the pre-prepared templates. Before the experment started, the ntervewees had been randomly dvded nto two groups. Each group conssted of fve ntervewees. To answer the questons, two groups of partcpants (A, B) alternately used two types (I, II) of techncal reports. The reports were related to the development of a chamber for delectrc spectroscopy. Report I had usual content (such as descrpton of tasks, a lst of requrements, descrpton of techncal processes) wrtten n MS Offce and Adobe PDF documents. Report II had the same nformaton as report I but t was recorded as a graphcal representaton by usng a DR capturng model. It s also necessary to say that the ntervewees had access to the fnal verson of the techncal drawngs wth both reports. TRANSACTIONS OF FAMENA XXXIX-1 (2015) 35

10 D. Rohde, M. Štorga, D. Maranovć Desgn Ratonale Capturng Model for Use durng the Embodment Phase of the Product Desgn Group A started the experment by usng the frst type of report (Report I) whle group B began the experment by usng the second type of report (Report II). After they fnshed wth the frst group of questons, Group A contnued wth Report II, and Group B wth Report I. In the same way, the partcpants responded to all questons prepared n the experment [Table 2]. Snce the experment requred concentraton of the partcpants, t was necessary to lmt the tme allowed for answerng questons. In order to determne the requred tme authors made a test experment, whch nvolved three ntervewees. All prerequstes for the man experment were also related to the testng experment (partcpants wthout experence regardng the observed proect). Table 2 Procedure of the experment Step Group of ntervewees Group of questons Report 1 A 1 I B 1 II 2 A 2 II B 2 I 3 A 3 I B 3 II 4 A 4 II B 4 I In the test experment, partcpants answered one queston from each group. They needed n average 15mn for answerng one queston. The nformaton obtaned and the experence ganed from the test experment was subsequently used to prepare the man experment. All answers to the gven questons collected durng the experment were evaluated for completeness and correctness [Table 3]. Table 3 Evaluaton metrcs Evaluaton metrcs completeness correctness Defnton The completeness of the nformaton returned by a partcpant. How much relevant nformaton s offered n a gven answer. The correctness of the nformaton returned by a partcpant Table 4 An example of a queston and assocated answer Queston Whch external propertes had an mpact on the choce of one of the gven alternatves for connectng the chamber to the "Aglent" measurng devce? Answer 1. Explotaton propertes 2. Economcal propertes 3. Manufacturng propertes 4. Functonalty All questons requred answers composed of multple enttes [Table 4]. For ths reason, the completeness and correctness were determned by countng correct and ncorrect enttes returned by the partcpants n the experment: Completeness: the number of correct enttes n a gven answer (from one partcpant) dvded by the total number of possble correct enttes n the techncal report. Correctness: the number of correct enttes n a gven answer dvded by the total number of enttes n the answer (from one partcpant). In ths way, answers could be compared because the lmtng values (mnmum and maxmum) for completeness and correctness were the same (0 to 1). 36 TRANSACTIONS OF FAMENA XXXIX-1 (2015)

11 Desgn Ratonale Capturng Model for Use durng the Embodment Phase of the Product Desgn D. Rohde, M. Štorga, D. Maranovć 6.2 Content of the reports used n the experment The documentaton that was utlzed n the preparaton and mplementaton of the experment was made durng the development of a chamber for delectrc spectroscopy of aqueous solutons. The document wth nformaton structured n eght chapters was used n the experment as Report I [Table 5]. Table 5 Content of the frst type of report (Report I) Chapter 1 Introducton 2 Tasks clarfcaton 3 Functonal decomposton Content 4 Techncal soluton prncples 5 Evaluaton and selecton of the best alternatve 6 Engneerng calculatons 7 Concluson 8 Appendx: Techncal documentaton Informaton from Report I was also used for preparng Report II but wrtten n a structured way usng the desgn ratonale elements proposed n the model n chapter 5 [Table 6]. Report II contaned 22 DRSs related to 22 problems for whch the development team proposed 52 alternatves n total. There were also 55 arguments dentfed related to these alternatves that were a base for 22 decsons. These problems were lnked wth 19 explanatons wth nformaton about facts, analyses and evaluatons. Fgure 3 shows an example of one DRS wth three alternatves for a gven problem, four arguments, two explanatons and one decson [Fg. 3]. Table 6 Desgn ratonale elements used n Report II Problem Actve Accepted/ Solved Reected Alternatve Argument Explanaton fact Explanaton analyss Explanaton evaluaton Decson TRANSACTIONS OF FAMENA XXXIX-1 (2015) 37

12 D. Rohde, M. Štorga, D. Maranovć Desgn Ratonale Capturng Model for Use durng the Embodment Phase of the Product Desgn Fg. 3 Graphcal representaton of one DRS Usng the CmapTools V5.04 tools t was possble to lnk the DR elements wth fles whch contan addtonal nformaton, for example a graphcal representaton of the functonal decomposton (Fg. 4, contnuous lne) or a table wth attrbutes of the DR element (Fg. 4, dashed lne). There are 69 nformaton obects (IO) used n Report II. Fg. 4 DR element and ts nformaton obects 38 TRANSACTIONS OF FAMENA XXXIX-1 (2015)

13 Desgn Ratonale Capturng Model for Use durng the Embodment Phase of the Product Desgn D. Rohde, M. Štorga, D. Maranovć Besdes the lnks between the DR elements of one DRS, these elements can be lnked wth the DR elements that are part of the other DRS (Fg. 5, dashed lne). If the user, by usng the cursor passes over the DR element n the DRS structure then the cloud wth short nformaton pops up (Fg. 5, contnuous lne). All elements n the DRS have a unque ID, e.g. P005, R049 (Fg. 5). Fg. 5 The lnk between the problem and the other DRS The comparson of the completeness and correctness of the answers offered by two groups (A and B) shows that Group A has gven better results (Fg. 6). Although the mean value for completeness s 11% better for Group A, t can be seen that for questons 1, 2, 5 and 6, the results of Group B are better. Ths result s such because partcpants from Group B provded answers to the mentoned questons by usng Report II. The mean value for correctness s 5% better for Group A, however, the results of Group B are not better for questons 5 and 6 although they used Report II. Ths can be explaned by the fact that for questons 5 and 6 Group B suggested more enttes (n the gven answer), but some of them were wrong (Fg. 6). Fg. 6 The comparson of completeness and correctness of answers for two groups (A and B) The analyss of the expermental results gves a comparson between completeness and correctness of answers to all questons (Fg. 7). It can be seen that the mean value for completeness s 26% and for correctness t s 16% better when partcpants used Report II. TRANSACTIONS OF FAMENA XXXIX-1 (2015) 39

14 D. Rohde, M. Štorga, D. Maranovć Desgn Ratonale Capturng Model for Use durng the Embodment Phase of the Product Desgn Fg. 7 The comparson between completeness and correctness of answers usng two reports (I and II) 7. Concluson Ths paper reveals our motvaton for conductng the research. In order to deal wth the prmary am, the research area and methodology are outlned. A revew of the lterature dentfed key concepts and ther relatonshps requred for understandng the ssues related to desgn ratonale capturng. The proposed desgn ratonale capturng model s presented as a result of the classfcaton of explanatons and arguments related to the correspondng desgn problem solutons and decsons that could be used n the conceptual, embodment and detal desgn stages. Most of these tems of nformaton are not documented n practce although they are essental for the decson process n product development wthn a partcular context. Some of the DR systems proposed n the lterature predct automated collecton, storage and retreval of nformaton and knowledge. However, due to the nformal nature of nformaton and knowledge, whch are the subect of ths study, there s a need to nvolve desgners n the process of knowledge management wthn the organsaton. Focusng on the embodment desgn stage, the fundamental logc of the IBIS system was expanded wth some new elements and attrbutes. The desgn ratonale scheme ncorporates fve elements: desgn problem, alternatve solutons, arguments, explanatons and decsons. The proposed model has been evaluated by an experment. In the experment, the tems of nformaton gathered durng the process of developng a chamber for delectrc spectroscopy of aqueous solutons were used. In the frst part of ths research, we nvestgated how the people nvolved n the product development (desgners) were motvated to capture knowledge and how much tme they were ready to devote to that actvty. It s obvous that ths extra work s not stmulatng, but through conversatons wth them, we found that by applyng certan measures desred cooperaton could be acheved. Such fndngs prmarly relate to the characterstcs of the future knowledge capturng system that has to tackle the needs of users (desgners), but employees need to be stmulated wth some reward, too. The comparson between completeness and correctness of the answers whch were offered by two groups of ntervewees showed that the defned elements and attrbutes of the desgn reasonng facltate the understandng of the proposed desgn ratonale capturng model and provde a bass for effectve search of nformaton. Regardless of the good expermental results t s necessary to mplement the proposed model nto the envronment of modern tools that support the product development process. Although capturng a sgnfcant amount of nformaton nto some knd of product data management (PDM) or product lfecycle management (PLM) system wll take tme, t should 40 TRANSACTIONS OF FAMENA XXXIX-1 (2015)

15 Desgn Ratonale Capturng Model for Use durng the Embodment Phase of the Product Desgn D. Rohde, M. Štorga, D. Maranovć be of mmedate beneft as t provdes desgners wth nformaton (reasons, arguments, alternatves, explanatons) whch nfluenced n prevous decsons. We beleve that such an approach could offer the followng advantages: the use of a PLM system database and search mechansms should provde effcent and smple procedures for the retreval of captured knowledge consstent and relatvely well-known methods and procedures for resolvng team collaboraton ssues n smultaneous work and the team sharng of desgn ratonale scheme dagrams the use of the "standard" PLM mechansm for creaton and mantenance of external lnks to all knds of product documentaton possbltes to develop sets of "predefned" elements and/or queres that could make desgn ratonale capturng and retreval processes easer and faster Of course, the mentoned advantages must be measured and valdated by expermental usage of such a system n desgn practce. In parallel wth practcal valdaton, future work wll be focused on some unresolved ssues and dlemmas that could be sources of problems n practcal usage, for example: how deep s t necessary to use "standard" PLM document management mechansms a compromse must be reached between potental benefts and the amount of extra desgners' work. We hope that the presented approach could contrbute to research efforts n desgn ratonale capturng tools as well as n the development of a new generaton of PLM systems whose applcaton should be extended to broader contexts and domans outsde the standard desgn documentaton whch serves as a descrpton of the fnal desgn only. REFERENCES [1] Hubka, V.: Theore der Konstruktonsprozesse, Berln, Hedelberg, New York: Sprnger - Verlag, [2] Burge, J., Brown, D. C.: Integratng Desgn Ratonale wth a Process Model, Workshop on Desgn Process Modellng, Artfcal Intellgence n Desgn '02, Cambrdge, UK, [3] Conway, A. P.: State of Art Revew - Approaches to Desgn Informaton Capture, Unversty of Strathclyde, [4] Ahmed, S.: Encouragng reuse of desgn knowledge: a method to ndex knowledge, Elsever Scence, Desgn Studes 26, , [5] McAlpne, H., Hcks, B. J., Huet, G., Culley, S. J.: An nvestgaton nto the use and content of the engneer s logbook, Elsever Scence, Desgn Studes 27, , [6] Lee, J.: Desgn ratonale systems: understandng the ssues, IEEE Expert: Intellgent Systems and Ther Applcatons 12(3), 78 85, [7] Myers, K. L., Zumel, N.B., Garca, P.: Acqurng Desgn Ratonale Automatcally, Artfcal Intellgence for Engneerng Desgn, Analyss and Manufacturng, Volume 14 Issue 2, Cambrdge Unversty Press, [8] Ishno, Y., Jn, Y.: An nformaton value based approach to desgn procedure capture, Advanced Engneerng Informatcs 20, , [9] Hu, X., Pang, J., Pang, Y., Atwood, M., Sun, W., Regl, W. C., A survey on desgn ratonale: representaton, capture and retreval, ASME Desgn engneerng techncal conferences, Baltmore, Maryland, [10] McCall, R. J.: PHI: A Conceptual Foundaton for Desgn Hypermeda, Desgn Studes 12 (1), 30 41, [11] Maclean, A., Young, RM., Bellott, V. M. E., Moran, T., Questons, Optons, and Crtera: Elements of Desgn Space Analyss, n Moran, T., Carroll, J., Desgn Ratonale Concepts, Technques, and Use, Lawrence Erlbaum Assocates, pp , [12] Lee, J., La, K.: What s n desgn ratonale, Human-Comput. Interacton, 6, pp , TRANSACTIONS OF FAMENA XXXIX-1 (2015) 41

16 D. Rohde, M. Štorga, D. Maranovć Desgn Ratonale Capturng Model for Use durng the Embodment Phase of the Product Desgn [13] Burge J. E., Bracewell R.: Guest edtoral of specal ssue: Desgn Ratonale, Artfcal Intellgence for Engneerng Desgn, Analyss and Manufacturng, 22, , [14] Bracewell R., Gourtovaa M., Moss M., Knott D., Wallace K., Clarkson J. P.: Dred 2.0: A Method and Tool for Capture and Communcaton of Desgn Knowledge Delberated n the Creaton of Techncal Products, Proceedngs of the 17th Int. Conf. on Engneerng Desgn ICED 09, Stanford Unversty, Stanford, USA, [15] Aursccho M., Gourtovaa M., Bracewell R. H. and Wallace K. M.: Evaluaton of how DRed desgn ratonale s nterpreted, Proceedngs of the 16th Int. Conf. on Eng. Desgn ICED 07, Pars, [16] Buckngham Shum S. et al., From gibis to MEMETIC Evolvng a Research Vson nto a Practcal Tool, Desgn Ratonale Workshop: Desgn, Computng & Cognton Conference, Endhoven, [17] Hcks, B. J., Culley, S. J., Allen, R. D., Mullneux, G.: A framework for the requrements of capturng, storng and reusng nformaton and knowledge n engneerng desgn, Internatonal Journal of Informaton Management 22, , [18] Roozenburg, N. F. M., Eekels, J.: Product Desgn: Fundamentals and Methods, ed. N. Cross and N. Roozenburg, John Wley & Sons, Chchester, [19] Blessng, L. T. M., Chakrabart, A.: DRM, a Desgn Research Methodology, Sprnger-Verlag London Lmted, [20] Aursccho, M.: Charactersng Informaton Acquston n Engneerng Desgn, Thess, Cambrdge Unversty Engneerng Department, [21] Rohde, D., Pavkovć, N., Aursccho, M.: Desgn Knowledge Indexng n Relatonal Database, Internatonal Desgn Conference DESIGN 2008, Dubrovnk Cavtat, [22] Rohde, D.: Embodment desgn ratonale, Thess, Unversty of Zagreb, Faculty of mechancal engneerng and naval archtecture, Zagreb, [23] N. N.: VDI gudelnes VDI 2225, [24] Štorga, M., Darlngton, M., Culely, S., Maranovć, D.: Traceablty of the development of 'nformaton obects n the engneerng desgn process, Research nto Desgn - Supportng Multple facets of Product Development / Chakarabart, Amaresh (ur.), ICoRD'09 Bangalore, Research Publshng, Inda, , Submtted: Accepted: Danel Rohde Danel.Rohde@netec.hr INETEC Insttut for Nuclear Technology Dolenca 28, Zagreb Maro Štorga Doran Maranovć Unversty of Zagreb Faculty of Mechancal Engneerng and Naval Archtecture Ivana Lučća 5, Zagreb 42 TRANSACTIONS OF FAMENA XXXIX-1 (2015)