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고온 분사 배기열에 의한 대류 열전달 특성 분석을 위한 수치 모델 연구
장호상(Ho Sang Jang),황세윤(Se Yun Hwang),이장현(Jang Hyun Lee) (사)한국CDE학회 2016 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2016 No.동계
This study introduces the convective heat transfer characteristics through the heat transfer analysis by high temperature exhaust gas that VTOL(Vertical Take-Off and Landing) ejects on deck. RANS(Reynolds Averged Compressible Navier-Stokes) equation are solved in conjunction with a two-equation (k − ε) turbulence model for two-dimentional impinging jet flow fields relevant to VTOL aircraft. To access the analysis method is impinging jet heat transfer model, jet nozzle of the VTOL was ejects on impinging wall(deck) using a CFD(Computational Fluid Dynamics). Obtain the similar result of temperature and pressure when compared to the result access the numerical methods. However, needs to try more research that convection coefficient in stagnation region.
유체-입자 연성 운동에 의한 굽힘형 배관의 침식률 수치해석
장호상(Ho-Sang Jang),이하원(Hawon Lee),황세윤(Se-Yun Hwang),이장현(Jang-Hyun Lee) 한국해양공학회 2017 韓國海洋工學會誌 Vol.31 No.1
The erosion of solid particles in a pipe elbow was numerically investigated. A numerical procedure to estimate the sand erosion rate, as well as the particle motion, in the pipe elbow flow was introduced. This procedure was performed based on the combined empirical erosion model and computational fluid dynamics (CFD) analysis to consider the interaction between the particle motion and the eroded surface. The underlying turbulent flow on an Eulerian frame is described by the Reynolds averaged Navier-Stokes (RANS) equations with a k-ϵ turbulent model. The one-way coupled Eulerian-Lagrangian motion of the air flow and sand particles is employed to simulate the particle trajectories and particle-wall interactions on the pipe surfaces. The predicted CFD erosion magnitudes are compared with experimental data from pipe elbows. The erosion rate results do not reveal a good accordance between the simulation and experimental results. It seems that the CFD shows a slightly over-predicted erosion ratio.
보온 재료에 따른 구명 조끼 별 단열성능의 비교 실험 및 해석
김성찬(Sung Chan Kim),이경훈(Kyung Hoon Lee),황세윤(Se Yun Hwang),장호상(Ho Sang Jang),이장현(Jang Hyun Lee) 한국항해항만학회 2016 한국항해항만학회지 Vol.40 No.1
구명 조끼는 익수자의 부력을 유지시키는 기능을 가지며, 낮은 해수 온도에서 저체온증에 빠지는 시간을 단축 시킬 수 있는 역할을 할 수 있다. 본 논문은 서멀 마네킹 실험과 수치적 방법을 적용하여 단열성능을 향상 시키기 위해서 개발된 팽창형 구명 조끼와 폼형구명 조끼의 단열성능 및 저체온증 방지 효과를 평가하였다. 단열성능 평가를 위해서 서멀마네킨을 이용하여 열유속 및 열저항을 계측하였으며, 본 연구에서 제시된 구명 조끼의 단열성능을 기존의 제품과 비교하여 검토하였다. 또한 저체온증에 빠지는 정도를 상대적으로 파악하기 위해서 유한요소해석을 이용하여 구명 조끼의 종류에 따른 체온 저감 시간을 예측하고 이를 비교 평가하였다. 저체온증 예측모델은 Pennes의 신체 열전달 해석 모델을 기반으로 작성되었으며, 실험으로부터 계측한 열저항 값을 이용하여 대류 열전달 조건을 환산하여 계산되었다. 그 결과 본 연구에서 단열성능을 향상시키기 위해서 제시된 하는 구명 조끼가 기존 제품에 비해 단열성능이 우수하게 평가됨을 확인하였다. Although the life jacket can provide the buoyance with the drowner, heat loss can make the drowned individual be subject to the hypothermia. In this study, The thermal insulation of two types life jacket including inflatable and foam type were evaluate by both experiments and numerical analysis. To estimate the thermal resistance of the jackets, experiments on the heat flux were conducted by the thermal manikin exposed to cold water. Heat flux loss on the surface of thermal manikin were measured for both foam and inflatable type life jacket. Also, finite element method is applied to a body section in order to understand the level of hypothermia of each life jacket. The segmental of human thigh is represented by a multi-layered section which considers the heat conduction within tissue, bone and fat. As a result, the thermal resistance and hypothermia time of each jackets have been compared based on the finite element analysis. It was found that the insulation ability of suggested life jackets is better than that of conventional type.
해빙 충격에 의한 해양구조물 콘크리트 구조의 마모 특성 고찰
이하원(Ha Won Lee),황세윤(Se Yun Hwong),장호상(Ho Sang Jang),이장현(Jang Hyun Lee) (사)한국CDE학회 2016 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2016 No.동계
This paper describes the characteristic abrasion mechanism of concrete structure by ice impact for the arctic offshore platform. In the present study, abrasion prediction method based on experimental studies were discussed, and main parameters that influence the abrasion of concrete structure, such as impact velocity, full penetration depth, structure shape and ice floe size, are investigated. In future work, based on present study, various ice-structure collision and abrasion scenarios will be analyzed.