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드릴십용 플레어 시스템의 설계승인을 위한 전산해석 절차
최주형,허태욱,Choi, Joo Hyoung,Heo, Tae Wook 대한기계학회 2013 대한기계학회 논문집. Transactions of the KSME. C, 산업기술과 혁신 Vol.1 No.1
플레어 시스템은 해저 원유 시추 시 폐 가스 및 오일을 연소시키는 장비로 폐 연료 연소 시 발생하는 고 열원으로부터 선체, 장비 및 인명을 보호하기 위한 해양플랜트 기자재이다. 플레어 시스템은 유정 시험 장비 중의 하나로서 선급의 설계승인을 필수적으로 받아야 하는 주요 장비이다. 본 연구에서는 플레어 시스템의 설계 승인을 위한 작업 중 전산해석과 관련된 부분에 대해서 소개하고자 한다. The Flare system is the offshore plant equipment for protecting humans and equipments from high heat radiations of waste gas and oil burning. As Primary equipment of well test systems, the flare system is essential Class(DNV, ABS etc) design certification. Therefore, this paper is introduced to be related to computational analysis of flare system design certification procedure.
단위입자 형상에 따른 하이브리드 기능소재의 역학적 특성해석
최주형(Joo-Hyoung Choi),조진래(Jin-Rae Cho) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
Traditional homogenization methods are limited to predict the equivalent material properties of FGMs because the detailed geometry information such as the particle shape and the dispersion structure is not considered. Accordingly, unit cell analysis based on superposition method were performed to obtain the equivalent material properties of hybrid functionally graded material. Hybrid functionally graded material with reinforcement of rectangle and triangle shape was modeled by unit cells. In this paper, the effects of various volume fractions, reinforcement shapes and angles on the mechanical behavior are studied numerically for hybrid graded materials.
기능경사 복합소재의 Global-Local 해석기법에 관한 연구
최주형(Joo-Hyoung Choi),조진래(Jin-Rae Cho) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
Most of the previous studies of FGMs have focused on the influence of the volume fraction distribution in the global sense. But, the response of phase materials in reality relies on the shape and size, the orientation and dispersion structure of constituents. Therefore, the modeling in the microstructure scopic level is essential for the accurate analysis of FGM. However, it requires too many degrees of freedom and the cost of computation. In this paper, we present a global-local analysis technique to predict the detailed stress state within the specific local region in FGM. The numerical experiments are carried out by considering the shape and the dispersion structure of Ni-Al₂O₃ FGM to illustrate the proposed technique.
타이어 롤링해석을 활용한 타이어마모량 예측에 관한 연구
최주형(Joo-Hyoung Choi),조진래(Jin-Rae Cho),김기전(Gi-Jeon Kim),우종식(Jong-Shik Woo) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
Tire wear of automobile is considered as an important factor to decrease the breaking and cornering performance. However, the tire rubber materials have been developed on an empirical basis up to the present time. Furthermore, one of the most expensive tests is the highway abrasion test. In this aspect, the numerical simulation approach is currently being widely employed. In this paper, we investigated the factors affecting the tire wear based on the mechanism of abrasive wear, and we found that the tire wear is closely related to frictional energy. Accordingly, the frictional energy is computed by utilizing the 3D dynamic rolling analysis of patterned tire. Finally, the amount of tire wear is predicted by correlating frictional energy with the wear equation.
기능경사 소재 등가 물성치 예측을 위한 균질화 기법의 특성분석을 위한 수치해석
조진래,최주형,신대섭,Cho, Jin-Rae,Choi, Joo-Hyoung,Shin, Dae-Sub 한국전산구조공학회 2008 한국전산구조공학회논문집 Vol.21 No.1
기능경사 소재(FGM)에는 서로 다른 두 가지 구성입자들이 혼합되어 있는 경사층(graded layer)이 삽입되어, 소재 전 영역에 걸쳐 구성입자의 체적분율이 연속적이고 기능적으로 변화하도록 되어있다. 이러한 이상(dual-phase) 입자복합재의 열 기계적 거동을 해석함에 있어 필수적인 경사층의 물성치는 전통적으로 균질화 기법을 이용하여 예측되었다. 하지만, 이러한 균질화 기법은 구성입자의 형태, 분산구조 등과 같은 상세 형상을 반영하지 못하지 때문에 복합재의 총체적인 등가 물성치 예측에만 국한 되어왔다. 이러한 맥락에서 본 연구에서는 경사층을 미시역학적으로 이산화 모델링하고, 다양한 체적분율과 외부 하중조건에 대해 유한요소해석을 실시하여 이러한 균질화 기법들의 특성을 분석하였다. Graded layers in which two different constituent particles are mixed are inserted into functionally graded material such that the volume fractions of constituent particles vary continuously and functionally over the entire material domain. The material properties of this dual-phase graded region, which is essential for the numerical analysis of the thermo-mechanical behavior of FGM, have been predicted by traditional homogenization methods. But, these methods are limited to predict the global equivalent material properties of FGMs because the detailed geometry information such as the particel shape and the dispersion structure is not considered. In this context, this study intends to investigate the characteristics of these homogenization methods through the finite element analysis utilizing the discrete micromechanics models of the graded layer, for various volume fractions and external loading conditions.
Alumina dummy 충전재를 이용한 GaN 기반 박막재료의 단면 TEM 시편준비
오상호,최주형,송경,정종만,김진규,유인근,유석재,김영민,Oh, Sang-Ho,Choi, Joo-Hyoung,Song, Kyung,Jeung, Jong-Man,Kim, Jin-Gyu,Yu, In-Keun,Yoo, Suk-Jae,Kim, Young-Min 한국현미경학회 2009 Applied microscopy Vol.39 No.3
Practical difficulties for preparing a good crosssectional specimen of GaN-based materials for transmission electron microscopy have arisen due to large difference of mechanical properties between hard ceramic substrate and soft GaN-layered materials. Uneven polishing, sudden cracking, delamination, and selective sputtering during the conventional wedge polishing technique are often encountered as experimental hindrances. The preparation technique based on Strecker's method can be applied to overcome these difficulties, which eventually leads to mechanically stable TEM samples independent of the mechanical properties of materials. The basic idea is to use hard ceramic dummy filler for embedding the sample of interest into the dummy frame. In this study, we applied this technique into preparing cross-sectional TEM specimen of the GaN-based materials with mechanical instability and demonstrated usefulness of this hard dummy filler method in which the possible modifications of the sample of interest during the preparation must be avoidable. In addition, practical precautions during the preparation were discussed.
투과전자현미경에 타소질 불순물의 오염 최소화를 위한 실험 조건
김영민,최주형,송경,김양수,김윤중,Kim, Young-Min,Choi, Joo-Hyoung,Song, Kyung,Kim, Yang-Soo,Kim, Youn-Joong 한국현미경학회 2009 Applied microscopy Vol.39 No.1
Contaminative artifacts such as carbonaceous materials on carbon-coated microgrids are unavoidable, which is induced by electron beam exposure inside electron microscopes. This phenomenon raise a source to produce confusing information to the samples investigated by analytical TEM, which should be alleviated as much as possible. As experimental precautions for reducing this unwanted effect, the use of $LN_2$ cooled anti-contaminator and pre-illumination of electron beam at low magnification can be helpful. Nevertheless, we should be cautious to set an illumination condition for microanalysis because the contaminative effect is dependent with the types of irradiation situations, which is well known to be a decisive factor for causing the carbonaceous artifacts. Accordingly, it is necessary that optimal illumination to minimize the contaminative effect should be selected for improving the accuracy of microanalysis. In this paper, we introduce the practical method to determine the optimal illumination condition by evaluating the contaminative effect as a function of instrumental spot size, which is directly linked with electron current density.
선박모션에 따른 고정식 CO<sub>2</sub>소화 장치 구조안전성 평가
김승찬,강상훈,최주형,김정환,박영철,Kim, Seung Chan,Kang, Sang Hoon,Choi, Joo Hyoung,Kim, Jeong-Hwan,Park, Young Chul 대한기계학회 2016 대한기계학회 논문집. Transactions of the KSME. C, 산업기술과 혁신 Vol.4 No.2
Since fire is one of the most dangerous threats to the safety of the ship, from the safety device is installed on the vessel the digestive apparatus can be viewed as the most important safety device. The fire-extinguishing device to be mounted to the vessel structure affected the stability of the structure in accordance with the blue of the sea. In particular, the Rack part of the basic safety of a fixed fire extinguishing system in the absence of a $CO_2$ container. In this paper, by utilizing simulation techniques to apply the pressure data being ejected in each direction by ship motion and $CO_2$ containers Rack perform an analysis of the structural safety assessment was part of the digestive system accordingly. 화재는 선박의 안전을 위협하는 가장 위험한 요소 중의 하나이므로, 선박에 설치되는 안전장치 중에서 소화 장치는 가장 중요한 안전장치라고 볼 수 있다. 선박에 탑재되는 고정식 소화 장치는 해상의 파랑에 따라 구조물의 안정성에 영향을 받는 구조이다. 특히 랙 부분은 이산화탄소용기를 고정시키는 부재로 소화 장치 중 기본적인 안전장치이다. 본 논문에서는 시뮬레이션기법을 활용하여 각 방향 별 선박모션 및 이산화탄소용기에서 분출되는 압력데이터를 적용하여 랙 유닛의 해석을 수행하였으며 이에 따른 소화 장치의 구조적 안전성을 평가하였다.