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오장현(Janghyun OH),이상욱(Sangwook LEE),안병의(Byungeui AHN) 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
In this study, the effect of surrounding parts on the retention force of open hood which is only maintained by safety hook at high speed driving was analyzed. Compared objects were mini MPV, mid-size coupe and submid-size hatchback, which have different hood shapes, respectively. Aerodynamic analysis was performed by PowerFLOW which is commercial software based on Lattice Boltzmann method. And structural analysis was performed by NASTRAN. Related to the effect of each part, the mass flow rate and pressure were investigated since the force is caused by the pressure difference between hood outer and inner panel. At first, the effect of the adoption, size variation, hole creation of under-cover were studied. Secondly, it was observed that there was the meaningful effect of the closing of bumper lower air intake by changing the mass flow, which imitates air shutter. Related to the heat exchanger, there was little effect of pressure drop for the range in this study. Finally, it was observed that the changing of engine size effects greatly on hood retention force.
1차원 과도 전도와 정전기 방전 현상에 관한 포논 전달의 몬테 카를로 모사
오장현(Jang Hyun Oh),이준식(Joon Sik Lee) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
At nanoscales, the Boltzmann transport equation (BTE) can best describe the behavior of phonons which are energy carriers in crystalline materials. Through this study, the phonon transport in some micro/nanoscale problems was simulated with the Monte Carlo method which is a kind of the stochastic approach to the BTE. In the Monte Carlo method, the superparticles of which the number is the weighted value to the actual number of phonons are allowed to drift and be scattered by other ones based on the scattering probability. Accounting for the phonon dispersion relation and polarizations, we have confirmed the one-dimensional transient phonon transport in ballistic and diffusion limits, respectively. The thermal conductivity for GaAs was also calculated from the kinetic theory by using the proposed model. Besides, we simulated the electrostatic discharge event in the NMOS transistor as a two-dimensional problem by applying the Monte Carlo method.
현재혁,오장현,박재훈,이제선 한국도시부동산학회 2022 도시부동산연구 Vol.13 No.2
This study aims to propose urban planning directions and strategies that enable building urban space safe from transmissive disease like COVID-19. Through reviewing published articles and interviewing experts of various urban fields, this study derived fourteen planning considerations and reassembled them into five urban planning directions: accssibility, self-sustainability, smart technology, health, and prevention. Also, eighteen strategies covering the following seven urban planning areas were proposed: land use, traffic infrastructure, green infrastructure, public facility, medical facility, residential environment, and urban environment. This study contributes to providing comprehensive urban planning directions and strategies necessary for planning resilient cities in POST-COVID-19 era. Specifying the proposed strategies into different approaches, implementing necessary policy improvements, and conducting pilot projects are required to applicate the result of this study into actual urban planning stage.
구조물 동적해석을 위한 현행 내진설계기준의 입력 지반 운동 선정 조건 타당성 평가 – II 지진응답
하성진,한상환,오장현 한국지진공학회 2017 한국지진공학회논문집 Vol.21 No.4
Current seismic design provisions such as ASCE 7-10 provide criteria for selecting ground motions for conducting response history analysis. This study is the sequel of a companion paper (I – Ground Motion Selection) for assessment of the ASCE 7-10 criteria. To assess of the ASCE 7-10 criteria, nonlinear response history analyses of twelve single degree of freedom (SDF) systems and one multi-degree of freedom (MDF) system are conducted in this study. The results show that the target seismic demands for SDF can be predicted using the mean seismic demands over seven and ten ground motions selected according to the proposed method within an error of 30% and 20%, respectively