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가스배관의 재질등급 및 충격에너지에 따른 연속연성파괴 거동분석
정효태(Hyo-Tae Jeong),최병학(Byung-Hak Choe),이영진(Young-Jin Lee),이정화(Jeong-Hwa Lee),홍기용(Key-Yong Hong),백종현(Jong-Hyeon Baek),김우식(Woo-Sik Kim) 한국가스학회 2012 한국가스학회지 Vol.16 No.5
가스배관 종류 및 사용 환경에 따른 거시적 파괴거동 평가해석을 위하여 1) 가스배관의 특성 및 환경에 따른 파괴거동 변화의 컴퓨터해석과 2) Battelle Two-Curve Method를 이용한 연속연성파괴거동 평가해석을 수행하였다. 새로운 사용환경의 가스와 오일의 배관계획이 진행되면서, 개선된 성능, 신뢰성, 그리고 경제성을 위한 재료가 요구되고 있다. 여기서 제시되는 연속연성파괴 해석은 높은 배관압력, 큰 배관직경과 같은 배관특성의 변화와 천연가스와 같이 다양한 성분을 함유하는 가스, 수소가스, 액화 이산화탄소 등과 같이 다양한 수송매체의 변화를 수용하기 위한 배관시스템에서 고려하여야 할 중요한 기술요소이다. To analyze the macroscopic fracture behavior as functions of the gas pipeline grade and the working environments, following analyses have been accomplished. Computer analysis of changes in fracture behaviors according to the working conditions of pipelines and Analysis of dynamic ductile fracture behaviors using the Battelle Two Curve Method. Recently, an economic and reliable pipe materials with improved performance has been needed for the severe pipeline working condition and new transporting materials. As the grade of pipe materials became higher, the possibility of dynamic ductile fracture could be increased. Therefore, the understanding of the technology to control and arrest the dynamic ductile fracture is important.
정효태(Hyo-Tae Jeong),최병학(Byung-Hak Choe),김우식(Woo-Sik Kim),백종현(Jong-Hyeon Baek) 한국가스학회 2014 한국가스학회지 Vol.18 No.3
이산화탄소 포집 및 저장 시스템(CCS, Carbon dioxide Capture and Storage system)의 수송배관에 대한 연속연성파괴(DDF, Dynamic Ductile Fracture)를 연구하기 위하여 Battlle Two Curve법(BTCM)으로 CCS수송배관의 연속연성파괴거동을 해석하여 천연가스 수송배관의 연속연성파괴거동과 비교하였다. 또한, CO₂배관에서의 배관두께 및 사용온도에 따른 연속연성파괴 민감도를 분석함으로써 연속연성파괴에 대한 사용기준을 해석하였다. 우리나라 기후조건에 따른 CO₂배관두께와 수송압력 사용기준을 분석하였으며, 상온의 경우에는 기존의 천연가스용 배관을 CO₂배관으로 사용하기 위해서는 배관두께가 7mm이상이어야 하고 수송압력은 54bar이하이어야 함을 해석하였다. Dynamic ductile fracture (DDF) has been studied in the transportation pipeline for the carbon dioxide capture and storage(CCS) system. DDF behavior of CCS transportation pipeline has been analyzed using Battelle Two Curve Method (BTCM) and compared with the DDF behavior of natural gas pipeline. The operating safety criteria against the DDF has been investigated based on the sensitivity analyses of the pipe thickness and the operating temperature for the CO₂ pipeline. The DDF criteria can be applied to confirm the operating safety of the CO₂ pipeline. If the commercial natural gas pipeline were used at room temperature as a CO₂ pipeline, the thickness of pipe should be at least 7mm and the pressure should be less than 54bar for the CO₂ pipeline system.
정효태(Hyo Tae Jeong),이정화(Jeong Hwa Lee),최병학(Byung Hak Choe),김우식(Woosik Kim) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.4
고강도 가스배관을 사용하여, 고압의 가스수송 압력으로 천연가스와 같은 다성분 가스를 수송하기 위해서는 연속연성파괴거동의 해석이 필요하며, 이때의 파괴저지인성값을 예측하기 위하여 BCTM에 근거한 다양한 예측모델을 검토하였다. 최근의 사용조건 변화에 따른 연속연성파괴거동을 해석하기 위해서는 수송압력의 변화에 따른 후프응력의 변화해석, 강도 변화에 따른 파괴속도 변화 해석, 천연가스 등의 다성분 가스에 대한 2 상감압거동의 해석이 필요함을 확인하였다.
자동차용 알루미늄 5185-폴리프로필렌 샌드위치 판재의 성형성
김기주,정효태,손일선,김철웅,김중배,Kim, Kee-Joo,Jeong, Hyo-Tae,Sohn, Il-Seon,Kim, Cheol-Woong,Kim, Joong-Bae 한국자동차공학회 2007 한국 자동차공학회논문집 Vol.15 No.2
The objective of this study was to develop formability evaluation techniques in order to apply aluminum sandwich panel for automotive body parts. For this purpose, newly adopting formability evaluation (using limit dome height and plane strain test) was carried out in order to secure the fundamental data for the measurement of sheet metal forming and the establishment of optimum forming conditions of the aluminum sandwich panel. The results showed that there were good agreements between the old formability evaluation method and the new method which was more simplified than that of old one. From the results of these formability evaluation, the formability of sandwich panel was higher than that of aluminum alloy sheet alone which was the skin component for the sandwich panel. Also, it was found that sandwich panel could reduce the weight and could have the same flexural rigidity simultaneously when it was compared to the automotive steel sheet.
Fe-Ni Invar 합금에서 나노 결정립 성장이 열팽창계수에 미치는 영향
임태홍,최병학,정효태,Yim, Tai Hong,Choe, Byung Hak,Jeong, Hyo Tae 한국재료학회 2014 한국재료학회지 Vol.24 No.10
The aim of this paper is to consider the effect of annealing on the coefficient of thermal expansion (CTE) of electroplated Invar Fe-Ni alloy. The CTE of the as-electroplated alloy is lower than those of alloys annealed at $400^{\circ}C$ and $800^{\circ}C$. XRD peaks become sharper as the as-electroplated alloy is annealed, which means the grain growth. The average grain sizes of as-electroplated and as-annealed alloys at $400^{\circ}C$ and $800^{\circ}C$ are 10 nm, 70 nm, and $2{\mu}m$, respectively, as determined by TEM and EBSD analyses. The CTE variation for the various grain sizes after annealing may come from the magnetostriction effect, which generates strain due to changes in the magnetization state of the alloys. The thermal expansion coefficient is considered to be affected by nano grain size in electroplated Fe-Ni Invar alloys. As grain size decreases, ferromagnetic forces might change to paramagnetic forces. The effect of lattice vibration damping of nano grain boundaries could lead to the decrease of CTE.