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유한 수심에서 반원형 부유체의 부가질량계수 약산식 개발
구원철(Weoncheol Koo),김준동(Jun-Dong Kim) 한국해양공학회 2013 韓國海洋工學會誌 Vol.27 No.1
This study is to develop the simplified formulae for added mass coefficient of a 20D floating body with a semi-circle section in a finite water depth. The semi-circle floating body may represent a simplified midship section transformed by Lewis form, which can be used for the ship motion analysis by strip theory. Since the added mass coefficient varies with motion frequencies and sea bottom effect, the correction factor representing the effect of water depth and frequencies is developed for accurate prediction of added mass. Using a two-dimensional numerical wave tank (NWT) technique based on the boundary element method(BEM) including sea bottom boundary the reference values of added mass are calculated to develop the correction factor. For verification and effectiveness of the formulae, the predicted added mass coefficients for various frequencies and water depth ratios are compared with the calculated values from NWT technique.
해저파일-지반 상호작용을 고려한 잭업 레그의 동적 응답 해석
허상환(Sanghwan Heo),구원철(Weoncheol Koo),박민수(Min-Su Park) 한국신재생에너지학회 2016 신재생에너지 Vol.12 No.1
Using the substructure method, numerical models of pile-soil interaction of diagonal and diamond types of jack-up legs were developed for dynamic response analysis. Wave and current forces acting on the leg were calculated using the modified Morison equation. Wind load was computed using the DNV formula. Modal analysis was performed to estimate the eigenvalues of the structure. The Newmark-beta method was used to calculate the dynamic behaviors of the structure in the time domain analysis. Maximum displacement and bending stress were computed for each type of leg. Reliability analysis was carried out for both types of legs to obtain a reliability index for the uncertainty of input wave periods.
경사형 진동수주 파력발전장치의 성능에 대한 실험적 및 수치적 연구
정현철(Hyen-Cheol Jung),구원철(Weoncheol Koo),JAN Youenn Herve 한국해양환경·에너지학회 2021 한국해양환경공학회 학술대회논문집 Vol.2021 No.5
본 연구에서는 이차원 미니조파수조를 이용하여 경사형 진동수주 파력발전장치의 모형실험을 수행하고 챔버내 수면변화를 분석하였다. 오픈챔버(Open Chamber) 조건의 경사형 진동수주 모델을 제작하여 미니수조에 설치하고, 피스톤형 조파기로 생성한 규칙파에 대한 진동수주실 내부의 파고를 계측함으로써 파력발전장치의 일차 에너지 변환 성능을 평가하였다. 수치해석(CFD) 모델링을 통해 규칙파 생성과 진동 수주실의 수면 변위를 계산하여 실험 결과와 비교하였다. 이를 통해 수치해석 모델링의 정확성과 실험 결과의 타당성을 검증하고 경사형 진동수주 파력발전장치의 에너지변환 효율을 평가하였다. In this study, a model experiment of an inclined oscillating water column (OWC) wave energy converter (WEC) was performed using a two-dimensional mini wave tank, and the variation of wave elevation in the chamber was analyzed. An inclined OWC model in open chamber condition was installed in the wave tank, and regular waves were generated with a piston-type wave maker. The wave elevations inside the chamber for the incident waves were measured and the primary energy conversion of the OWC WEC was evaluated. Through numerical analysis (CFD) modeling, wave elevations in the chamber were calculated and compared with the experimental results. Through this, the accuracy of the numerical modeling and the validity of the experimental results were verified, and the energy conversion efficiency of the inclined OWC WEC was evaluated.
수직 진자형 파력 발전 장치의 운동성능 및 파력 추출에 관한 실험적 연구
김성재(Sung-Jae Kim),구원철(WeonCheol Koo),민은홍(Eun-Hong Min),장호윤(Hoyun Jang),윤동협(Donghyup Youn),이병성(Byeongseong Lee) 한국해양공학회 2016 韓國海洋工學會誌 Vol.30 No.5
The aim of this study was to experimentally investigate the hydrodynamic performance of a hemispheric wave energy converter (WEC) and its wave power takeoff. The WEC is a heaving body-type point absorber with a hydraulic-pump power take-off (PTO) system. The hydraulic PTO system consists of a hydraulic cylinder, hydraulic motor, and generator, with consideration given to the hydraulic pressure and flow rate. Two body model shapes, including the original hemisphere and a bottom-chopped hemisphere, were considered. The heave RAOs of the two models were evaluated for various body drafts. The effects of the hydraulic PTO system on the RAOs were also investigated.