• 반도체디스플레이기술학회지
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• 제16권3호
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• pp.71-77
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• 2017

As the automobile industry has shifted to software, the Automotive SPICE standard has been established to ensure efficient product development process and quality. In the assessment model, the HIS Scope is the minimum standard for small and medium automotive electric companies to meet OEM requirements. However, in order to achieve the HIS Scope, the output of each process stage that meets the verification criteria of Automotive SPICE must be created. In particular, the test phase takes a lot of resources, which is a big burden for small and medium-sized companies. In this paper, we propose a methodology for creating test cases of software integration test phase based on UML sequence diagram, which is a software design phase of Automotive SPICE HIS Scope, by applying behavior model based testing method. We also propose a tool chain for automating the creation process. This will reduce the resources required to create a test case.

• 한국수소및신에너지학회논문집
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• 제34권2호
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• pp.169-177
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• 2023

Phase stability diagrams were constructed for magnesium alanate (Mg(AlH₄)₂) nanoparticles to investigate the reversible hydrogen storage reaction by using density functional theory. Our findings indicate that bulk Mg(AlH₄)₂ shows favorable hydrogen release, but unfavorable hydrogen uptake (adsorption) reactions. However, for Mg(AlH₄)₂ nanoparticles, it was observed that hydrogen release and recharge can be achieved by controlling the particle size and temperature. Furthermore, by predicting the decomposition phase diagram of Mg(AlH₄)₂ nanoparticles with varying hydrogen partial pressure, it was discovered that reversible dehydrogenation reactions can occur even in relatively large nanoparticles by controlling the hydrogen partial pressure.

• 한국콘텐츠학회논문지
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• 제9권5호
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• pp.61-75
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• 2009

통상적으로 데이터베이스 어플리케이션을 구현하는 과정은 ERD(Entity Relationship Diagram)와 프로세스 모델을 산출하는 분석 과정을 거쳐 코딩, 테스팅 (testing)으로 프로젝트를 완성한다. 이 과정에서 가장 정형화되지 못한 부분이 분석과정으로 (1) 고객이 자신이 원하는 시스템의 세부 사항까지 알지 못한다; (2) 고객의 비즈니스 (business) 로직을 개발자가 이해하기 어렵다; (3) 분석 산출물인 ERD와 프로세스 모델을 고객이 이해하기 어렵다 등의 이유 때문이다. 본 논문은 분석 과정을 효과적으로 수행하기 위하여 가장 중요한 분석 산출물인 ERD (Entity Relationship Diagram)를 고객이 이해하기 쉬운 폼 형태로 제시할 것을 제안한다. 이 폼들은 데이터를 입력할 수 있게 하여 고객이 입체적으로 모델을 평가할 수 있어야 하며 분석 과정에서 발견되는 비즈니스 로직을 즉각 구현하여 고객이 이 폼들을 실행하면서 구현되는 로직을 평가, 이해하여 비즈니스 로직을 세부적으로 제공할 수 있게 하여야 한다. 이 목적을 위하여 고객이 제공하는 비즈니스 로직을 폼과 폼끼리의 참조를 포함하는 데이터 플로우(data flow) 형태로 우리의 폼 시스템에서 구현할 수 있어야 한다. 고객은 추상적인 ERD 대신에 데이터를 포함하고, 데이터 플로우 로직이 구현되어 있는 폼들을 실행 시켜 보면서 자신이 제공한 비즈니스 로직을 검토할 수 있으며 새로운 로직을 발견할 수 있다. 이러한 과정을 반복적으로 수행하면서 고객과 개발자는 충분히 세부적이고 모순이 없는 분석 과정을 성공적으로 수행할 수 있게 된다.

• 한국재료학회지
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• 제26권12호
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• pp.709-713
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• 2016

Grain morphology, phase stability and mechanical properties in binary Ti-Al alloys containing 43-52 mo1% Al have been investigated. Isothermal forging was used to control the grain sizes of these alloys in the range of 5 to $350{\mu}m$. Grain morphology and volume fraction of ${\alpha}_2$ phase were observed by optical metallography and scanning electron microscopy. Compressive properties were evaluated at room temperature, 1070 K, and 1270 K in an argon atmosphere. Work hardening is significant at room temperature, but it hardly took place at 1070 K and 1270 K because of dynamical recrystallization. The grain morphologies were determined as functions of aluminum content and processing conditions. The transus curve of ${\alpha}$ and ${\alpha}+{\gamma}$ shifted more to the aluminum-rich side than was the case in McCullough's phase diagram. Flow stress at room temperature depends strongly on the volume fraction of the ${\alpha}_2$ phase and the grain size, whereas flow stress at 1070 K is insensitive to the alloy composition or the grain size, and flow stress at 1270 K depends mainly on the grain size. The ${\alpha}_2$ phase in the alloys does not increase the proof stress at high temperatures. These observations indicate that improvement of both the proof stress at high temperature and the room temperature ductility should be achieved to obtain slightly Ti-rich TiAl base alloys.

• 대한화학회지
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• 제42권6호
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• pp.599-606
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• 1998

산화물 초전도체 발견 후 많은 이론적 발전이 있었으나, 초전도 상전이를 정확히 설명하는 이론은 아직 없다 하겠다. 특히 상전이점 근처에서 발견되는 이중전이(double transition)나 다양한 자기적 상전이에 대해서는 아직 정확한 이해가 없는 상태이다. 본 논문에 서는 전자유체의 응축모델을 사용하여 초전도 전이에 있어서, 전자기체의 응축과정이 CONFINEMENT와 TRAP의 두 단계로 일어남을 알았다. 이 두 단계 전이 메카니즘은 이중전이를 잘 설명할 뿐만 아니라, 여러 형태의 초전도에서 보이는 자기적 성질, 특히 다양한 vortex structure를 보여주는 magnetic phase transition을 잘 설명할 수 있었다. 여러 종류의 초전도체들에서 공통적으로 발견되는 double transition과 다양한 magnetic phase transition을 잘 설명할 수 있는지 여부가 초전도 현상 설명의 일반이론으로 적합한지를 결정할 것이다.

• 한국전기전자재료학회논문지
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• 제16권12S호
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• pp.1278-1285
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• 2003

This study investigated the phase transformation of the REBa$_2$Cu$_3$$O_{7-x}$ (RE=Nd, Gd, Dy) superconductor, and CCT (Continuous-Cooling-Transformation) along with the TTT (Time-Temperature-Transformation) diagrams are suggested according to the isothermal and continuous cooling heat-treatments. The peritectic temperature of the 123 phases decreased approximately 3$0^{\circ}C$ when the ionic radius of the rare-earth elements was reduced. The optimum cooling rate where BC and Cu-free phases do not exist was 0.001$^{\circ}C$/s. At this cooling late, the 123 phase grew with a c-axis Perpendicular to the surface and had a well-distributed 211 phase. When the oxygen partial pressure was reduced Outing isothermal heat-treatment, the formation temperature of the 211 phase decreased. In addition, the formation temperature of the 123 phases decreased from 100$0^{\circ}C$ (Nd-123) to 9$25^{\circ}C$ (Gd-123), and finally 875$^{\circ}C$ (Dy-123) according to the decrease in the ionic radius of the tare-earth elements. Compared to Nd-123, Gd- and Dy-123 had a better texture with a well-distributed 211 phase.e.

• 열처리공학회지
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• 제29권5호
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• pp.227-233
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• 2016

Phase transformation phenomenon at high temperature was investigated by using designed TiAl-Nb alloys with addition of the ${\beta}$ stabilizer. Examination of dendritic morphologies in arc-melted button ingot could reveal the crystallography of the primary solidification phase. It was found that the addition of ${\beta}$ stabilizer(Nb) shifted the high temperature region of the binary Ti-Al phase diagram to the high Al composition side so that ${\beta}$ phase forms as a primary crystal even at higher Al composition compared with the binary Ti-Al system. The ${\beta}$ was found to be the primary solidification phase for alloys with Al content less than about 52 at.%. The composition of ${\beta}$ solidification in Ti-Al-Nb ternary system could be determined from the partial liquidus projection which was constructed by observing the microstructure of arc-melted buttons. The Ti-46Al-(6, 8)Nb composition was selected for ${\beta}$ solidification and the directional solidification was performed by a floating zone-type DS apparatus at the growth rate 30 mm/hr respectively.

• 한국산학기술학회논문지
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• 제13권8호
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• pp.3698-3703
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• 2012

건축설계과정은 프로그래밍 단계와 디자인 단계로 구분된다. 현대물리학 개념에 기초한 현대건축이론은 자료를 통합하는 디자인 단계에 적용되어 설계된다. 건축장 또한 디자인 단계에서 진행된다. 건축장은 건축장 특성으로 일체성, 상호성, 영역성을 구현하여 설계가 된다. 그리고 이 특성은 설계 시 고려하는 사항 및 접근하는 관점과 사고의 범위에 따라 영역성, 상호성, 일체성의 설계과정으로 진행이 된다. 영역성 설계는 주변 환경 및 구조물 등과 대지의 관계조직체계를 계획한다. 상호성 설계는 건축물이나 공간 등 상호 영향을 주고받는 상호간의 관계망을 계획한다. 일체성 설계는 공간과 건축물이 만나는 방식을 설계하는 것이다. 영역성과 상호성에서 설정된 설계 방향을 구현하고자 어떠한 방식이나 형상을 계획할 것인지에 관하여 구체적인 내용을 계획하게 된다. 결론적으로 건축장 특성을 정의하는 일련의 설계과정에 의하여 건축장이 만들어 진다.

• Journal of Welding and Joining
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• 제28권3호
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• pp.104-113
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• 2010

In this study, to predict the microstructure in weld HAZ of low alloyed steel, prediction model for the phase transformation considering the influence of prior austenite grain size and cooling rate was developed. For this study, six low alloyed steels were designed and the effect of alloying elements was also investigated. In order to develop the prediction model for ferrite transformation, isothermal ferrite transformation behaviors were analyzed by dilatometer system and 'Avrami equation' which was modified to consider the effect of prior austenite grain size. After that, model for ferrite phase transformation during continuous cooling was proposed based on the isothermal ferrite transformation model through applying the 'Additivity rule'. Also, start temperatures of ferrite transformation were predicted by $A_{r3}$ considering the cooling rate. CCT diagram was calculated through this model, these results were in good agreement with the experimental results. After ferrite transformation, bainite transformation was predicted using Esaka model which corresponded most closely to the experimental results among various models. The start temperatures of bainite transformation were determined using K. J. Lee model. Phase fraction of martensite was obtained according to phase fractions of ferrite and bainite.

• 열처리공학회지
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• 제27권1호
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• pp.15-22
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• 2014

This study is to investigate the phase changes and cold workability after isothermal transformation at $780^{\circ}C$ by using the high temperature gas nitrided (HTGN) STS 430 ferritic stainless steel specimens. The phase diagram of STS 430 steel obtained by calculation showed that the phase appeared at $1100^{\circ}C$ showed as ${\alpha}+{\gamma}{\rightarrow}{\gamma}{\rightarrow}{\gamma}+Cr_2N{\rightarrow}{\gamma}+Cr_2N+CrN$ with increasing nitrogen concentration. Also, the transformation of ${\gamma}{\rightarrow}Cr_2N$ during heat treatment isothermally at $780^{\circ}C$, nitrogen pearlite with lamellar type was fully formed at the nitrogen permated surface layer for 10 hrs. However, this transformation was not completed for 1 hr, resulting nitrogen pearlite plus martensite. The cold rolled specimen of isothermally transformed at $780^{\circ}C$ for 10 hrs after high temperature gas nitriding decreased the layer thickness of nitrogen pearlite inducing the deformation of hard $Cr_2N$ phase. the dissolution rate of $Cr_2N$ phase increased rapidly with increasing cold rolling ratio. Specimens with the microstructure of nitrogen pearlite (isothermally transformed at $780^{\circ}C$ for 10 hrs) were possible to cold rolling without crack formation. However, the mixed structures of nitrogen pearlite + martensite (isothermally transformed at $780^{\circ}C$ for 1 hr) were impossible to cold deformation without cracking.