머리말

장영원,나경환 한국소성가공학회 2004 단조 심포지엄 Vol.2004 No.6

고탄소강 bloom 의 연속주조시 macro 편석 발생거동

장영원,오경식,이인열 대한금속재료학회(대한금속학회) 1993 대한금속·재료학회지 Vol.31 No.11

The macrosegregation behavior in continuously cast(CC) high carbon steel blooms are systematically investigated by carrying out a plant test using a bloom caster at POSCO in connection with the electro-magnetic stirring(EMS) mode and stirring force. The degree of centre soundness is quantitatively measured in terms of the area fraction and size distribution of centre porosity as well as the segregating solutes by using a mapping analysis method. The thicknesswise solidification structures are examined to find out solidification behavior in the centre region of CC blooms and the calculation of specific permeability(k) is also presented to elucidate the formation mechanism of centre defects. The addition of a final stirring(FEMS) to an in-strand EMS(SEMS) is found to increase the solidification rate significantly in the final stage resulting in a more fine distribution of porosities and segregation spots in CC blooms. An optimum stirring forces of SEMS and FEMS are then determined to provide the best centre soundness for the high carbon steel tested. The most effective conditions at the final stage of solidification for the reduction of macrosegregation in CC blooms have also been suggested as a result of this study.

Ti-6Al-4V 합금의 α상 형상에 따른 미세균열 생성거동

장영원,박찬경,이종수,배기만 대한금속재료학회(대한금속학회) 1993 대한금속·재료학회지 Vol.31 No.1

The purpose of this study is to investigate the deformation characteristics and microcrack initiation behavior depending on the microstructure of Widmanstatten-α(Wα) and equiaxed-α(Eα) in a Ti-6Al-4V Alloy. In Wα structure, microcracks were observed to form along the α/β interfaces, the colony boundaries and the grain boundary α layers both in tension and fracture tests. In Eα structure, most of microvoids were found to form at the α/β interfaces. The lower tensile strength and ductility of Wα structure was mainly due to the strain localization along the prior β grain boundaries and colony boundaries, which was preceded by the easy slip transfer through α/βinterfaces within the colony. The large increase in fracture toughness of Wα structure was, however, primarily attributed to the crack path deviation depending on the colony orientation.

서비스 지향 아키텍쳐 기반 P2P 비즈니스프로세스 모델링

장영원(Yongwon Chang),이명희(Myounghee Lee),유철중(Cheoljung Yoo),장옥배(Okbae Chang) 한국정보과학회 2006 한국정보과학회 학술발표논문집 Vol.33 No.1

XML이후 컴포넌트를 중심으로 개발된 통합 애플리케이션과 함께 서비스를 중심으로 한 서비스 지향 아키텍쳐가 새롭게 웹서비스를 확장시킨다. 웹서비스를 기본으로 하는 구조이면서 보다 IT 기반을 개선하고 비즈니스 요구에 보다 빠르게 응답할 수 있는 서비스지향 아키텍쳐에서 각 컴포넌트들의 서비스의 효율을 높이기 위한 여러 가지 방법이 요구된다. 본 논문에서는 이러한 기업간 비즈니스 프로세스통합을 위해 가치를 적용한 P2P프로세스를 모델링한다. 기존 프로세스간 인터페이스를 통합하고 체계적이며 가시적인 모델링을 서비스 지향 아키텍쳐에 적용하여 보다 가시적이고 효율적인 아키텍쳐를 제안한다.

서비스 지향 아키텍처 기반의 모바일 서비스 모델링

장영원(Young-Won Chang),유철중(Cheol-Jung Yoo),노혜민(Hye-Min Noh) 대한전자공학회 2008 電子工學會論文誌-SD (Semiconductor and devices) Vol.45 No.2

서비스 기반 아키텍처(Service-Oriented Architecture;SOA) 등장 이후 서비스와 애플리케이션을 상호 연결하는 측면에서 여러 가지 접근 방법들이 개발되고 있다. 모바일과 같은 정보기기는 일반적인 접근법이나 전통적인 접근법과는 달리 메모리와 프로세스 등 단말기 자체의 제약과 스크린 및 입출력 및 사용자 인터페이스의 제약이 많아 여러 가지가 고려되어 설계되어야 한다. 본 연구는 서비스를 기반으로 한 구조에서 많은 제약을 갖는 모바일의 효율성을 높이기 위해 모바일 애플리케이션 요구사항을 분석하고 명세한 후 설계 방법을 최적화하고, 서비스 유스케이스 테스팅을 위한 확장된 유스케이스 명세를 제공하고, 서비스 명세로부터 서비스간 상호운영 테스트를 한다. 또한 모바일 애플리케이션의 성능을 확장하고, 제약을 최소화 할 수 있는 과정을 제시하며 유스케이스 테스팅을 위한 명세 방법과 서비스 상호간 상호운용성 보장 테스팅을 수행한다. 본 연구는 서비스 지향 아키텍처를 기반으로 모바일 서비스 명세 방법과 애플리케이션 테스팅 방법에 대한 아이디어를 제공한다는데 그 의의가 있다. Recently, the need for accessing information from anywhere at any time has been a driving force for a variety of mobile applications. As the number of mobile applications increases rapidly, there has been a growing demand for the use of Service Oriented Architectures(SOA) for various applications. Mobile based SOA offers a systematic way to classify and assess technical realizations of business processes. But mobile has severly restricted range of utilizing services in computing environment and more, a mobile computer is envisioned to be equipped with more powerful capabilities, including the storage of a small database, the capacity of data processing, a narrow user input and small size of display. This paper present mobile adaption method based on SOA to overcome mobile restriction. To improve mobile efficient we analyzing mobile application requirement, writing service specification, optimizing design, providing extended use case specification which test use case testing and testing service test case which derived from service specification. We discuss an mobile application testing that uses a SOA as a model for deploying discovering, specifying, integrating, implementing, testing, and invoking services. Such a service use case specification and testing technique including some idea could help the mobile application to develop cost efficient and dependable mobile services.

Ti-6Al-4V 합금의 초소성 특성에 미치는 α/β상분율의 영향

장영원,이종수,김지식 대한금속재료학회(대한금속학회) 1997 대한금속·재료학회지 Vol.35 No.7

Present investigation has been made to study the superplastic deformation behavior of Ti-6Al-4V alloy with respect to the variation of α/β volume fraction. Load relaxation and superplastic deformation tests have been carried out at 600℃ and 800℃, to obtain stress-strain rate curves and tensile elongations for the microstructures of 3 and 11㎛ grain sizes. The experimental results have been analyzed by the theory of inelastic deformation which consists of two mechanisms, i.e., the grain matrix deformation and the phase/grain boundary sliding. Grain matrix deformation observed at 600℃ is consistent with an iso-stress model for the deformation of fine grain microstructures (3㎛) in which the β volume fractions are varied. However, the coarse grain microstructures (11㎛) reveal the deformation behavior of mixed type between. iso-stress mode and iso-strain rate mode. Phase boundary sliding occurring at 800℃ is the most effective in 48% β structure, resulting in the largest elongation, The sliding resistance in the different types of grain boundary is increased in the order of α/β≫α/α≒ β/β.

연성균열 및 입계취성균열의 미시적 전파기구

장영원,박찬경,박찬로 대한금속재료학회(대한금속학회) 1992 대한금속·재료학회지 Vol.30 No.8

In-situ tensile deformation tests of molybdenum were carried out in a transmission electron microscope at temperatures ranging from 120K to room temperature. At all test temperatures, brittle crack propagation was observed to precede plastic deformation. The characteristics of cracks, either ductile or brittle, was found to vary depending on crack geometry and loading condition. In some cases the coexistence of brittle and ductile crack was observed and in other instances crack propagation changed from brittle to ductile mode. Such phenomena could be successfully explained by the concept of local stress intensity factor for dislocation emission and brittle crack propagation. Dislocations generated at a crack tip are thought to shield the crack. The shielding of a crack by emitted dislocations would then increase the fracture toughness of materials. On the other hand, the anti-shielding of a crack by externally generated dislocations could occur, just like the shielding due to dislocations generated at the crack tip to reduce the toughness of materials.

자동항법을 지원하는 UAV 하드웨어 구현

장영원,B.Batmunkin,이덕진,정길도 대한전기학회 2011 정보 및 제어 심포지엄 논문집 Vol.2011 No.4

TRIP 형 강의 변태키네틱스 및 가공경화 거동

장영원 대한금속재료학회 ( 구 대한금속학회 ) 1997 대한금속재료학회 학술대회 개요집 Vol.1997 No.1

머리말

장영원,나경환 한국소성가공학회 2003 단조 심포지엄 Vol.2003 No.10