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정광효(Kwang-Hyo Jung),서성부(Sung-Bu Suh),박성부(Sung-Boo Park) 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6
This study is to calibrate the surface flow accelerator to make a uniform vertical velocity distribution. This experiment is carried out circulating water channel with employing PIV technique. The vertical and horizontal velocity distributions are illustrated for two different impeller rpm with varying surface flow accelerator rpm. This experimental approach suggests how to measure, the velocity uniformity near free surface. Also, the velocity uniformity could be quantified in direction vertical and horizontal.
PIV시스템을 이용한 규칙파중 2차원 사각형 부유식 구조물 주위의 유동특성 연구
정광효(KWANG-HYO JUNG),전호환(HO-HWAN CHUN) 한국해양공학회 2006 韓國海洋工學會誌 Vol.20 No.6
This experimental study investigated the flow characteristics for regular waves passing a rectangular floating structure in a two-dimensional wave tank. The particle image velocimetry (PIV) was employed to obtain the velocity field in the vicinityof the structure. The phase average was used to extract the mean flow and turbulence property from repeated instantaneous PIV velocity profiles.The mean velocity field represented the vortex generation and evolution on both sides of the structure. The turbulence properties, including the turbulence length scale and the turbulent kinetic energy budget were investigated to characterize the flow interactionbetween the regular wave and the structure. The results show the vortex generated near the structure corners,which are known as the eddy-making damping or viscous damping. However, the vortex induced by the wave is longer than the roll natural period of the structure, whichpresents the phenomena opposing the roll damping effect; that is, the vortex may increase the roll motion under the wave condition longer than the roll natural period.
Round-Bilge 고속 반활주선의 선형특성 및 설계에 관한 연구
이정관(Jung Gwan Lee),정광효(Kwang Hyo Jung),서성부(Sung Bu Suh),전호환(Ho-Hwan Chun),이인원(Inwon Lee) 한국해양공학회 2010 韓國海洋工學會誌 Vol.24 No.4
This study presents the design procedure for optimizing the semi-planing hull form, including appendages, using numerical and experimental methods. Four different referenced semi-planing hull forms were compared to determine their hydrodynamic performances, and one at the hull forms was modified for optimum operation at high-speed conditions (0.4 < FNL < 0.9). The optimized, semi-planing hull form was tested in the towing tank to investigate its resistance characteristics. Also, the results of the model tests with differing design parameters were used to choose the stem wedge and the spray strip to improve the hydrodynamic performance at high speeds.
윤종성(JUNG-SUNG YOON),김명규(MYOUNG-KYU KIM),정광효(KWANG-HYO JUNG),김가야(GA-YA KIM) 한국해양공학회 2008 韓國海洋工學會誌 Vol.22 No.3
In this study, flow and creation and dissipation of vorticity around rectangular floating breakwater is investigated both experimentally and numerically. The PIV system(Particle image velocimetry) is employed to obtain the velocity field in the vorticity of rectangular structure. The numerical model, combined with k-ε turbulence model and the VOF method based on RANS equation, is used to analyze the turbulence structure. In the results of this study, the vorticity is found around conner of rectangular structure at all time domain, and creation and dissipation of vorticity are closely related to wave period. Separation points of phase of vortex due to flaw separation for longer period waves are faster then for shorter period waves.
부산 연안지형 VRS-GPS 계측을 통한 태풍해일 침수예측
김가야(Ga-Ya Kim),정광효(Kwang-Hyo Jung),김정호(Jeong-Ho Kim) 한국해양공학회 2012 韓國海洋工學會誌 Vol.26 No.1
A coastal flood area was predicted using the empirical superposition of the typhoon surge level and typhoon wave height along the Busan coastal area. The historical typhoon damages wore reviewed, and the coastal topography was measured using VRS-GPS. A FEMA formula was applied to estimate the coastal. flood area in a typhoon case when the measured and predicted dam of typhoon waves are not available. The results in the area of Haeundae beach and Gwangalli beach were verified using the flood area dam from the case of Typhoon Maemi (2003). If a Hurricane Katrina class typhoon were to pass through the Maemi trajectory, the areathat would be flooded along the Busan coastal. area was predicted and compared with the results of the Maemi case. Because of the lack of ocean environment data such as data for the sea level, waves, bathymetry, wind, pressure, etc., it is hard to improve the prediction accuracy for the coastal flood area in the typhoon case, which could be reflected in the policy to mitigate a typhoon’s impact. This paper discusses the kinds of ocean environment information that is needed to predict a typhoon’s impact with better accuracy.