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파랑 중 선박의 운동을 고려한 조종성능 해석 기법에 대한 연구
성영재,이현호,이태일,김성은 한국해양환경·에너지학회 2012 한국해양환경공학회 학술대회논문집 Vol.2012 No.5
For the reliable estimation of manoeuvring performances in waves, a numerical simulation program was developed. The program uses 3D panel method to consider the effects of radiation, diffraction and forward speed. Supplementary viscous damping terms, which arc analogous to the hydrodynamic derivatives in the system based manoeuvring simulation, were adopted to account for the viscosity effects on the manoeuvring elated horizontal plane forces and moment. Values of the supplementary damping coefficients were determined by the numerical calibration using the captive model test data in calm sea conditions so that the predicted hull forces and moment can match the experimental data. Captive model tests in regular waves were also conducted to validate the estimated manoeuvring forces in waves. Simulated manoeuvring motions in calm water and in waves were compared with the fee sailing model test results. Through this study, w could find that the developed program gives liable estimate not only on the manoeuvring forces in waves but also on the variation of stability characteristics of a ship with its relative position in waves.
Estimating the parameters of exponentiated logistic distribution under progressive censoring scheme
성영재,이경준 한국데이터정보과학회 2019 한국데이터정보과학회지 Vol.30 No.6
The exponentiated logistic distribution can be considered as a proportional reversed hazard family with the baseline distribution as the logistic distribution. The exponentiated logistic distribution has been used to model the data with a unimodal density. The main aim of this paper is to propose the estimators of the parameters (when shape parameter is known) of the exponentiated logistic distribution under progressive censoring (PC) scheme. First, we derive the maximum product spacings estimators for parameters of exponentiated logistic distribution. And we derive the approximate maximum product spacings estimators for parameters of exponentiated logistic distribution using Talyor series expansions. We also compare the maximum product spacings estimators and approximate maximum product spacings estimators in the sense of the root mean squared error and bias for various PC schemes. In addition, real data example based on progressive censoring scheme have been also analysed for illustrative purposes.
선미 벌브 스케그가 선박 조종성능에 미치는 영향에 관한 실험적 연구
안경수,성영재,신상성,이태일 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6
In this paper, the effects of stern bulb skeg on ship's maneuverability were investigated. The skeg is one of the afterbody appendages and generally fitted below the stern bulb, and it plays a role as the course stabilizing fin. To examine the effects of stern bulb skeg on ship's maneuverability, PMM tests of four ships with and without stern bulb skeg were carried out and analyzed. The results showed that the stern bulb skeg mainly has influence on the linear hydrodynamic coefficients of hull. The effects of stern bulb skeg on the linear hydrodynamic coefficients of hull were expressed as empirical formula through regression analysis. The simulation results using this formula were compared with model test results.
최양호,노영재,성기탁,장대수 한국자연보호학회 2013 한국자연보호학회지 Vol.7 No.2
The distribution of dissolved oxygen (DO) and its variability in Chunsu Bay were studied. Monthly hydrographic survey and realtime monitoring for water quality conditions were carried out in study area. Vertical distribution of DO shows the formation of hypoxia in the bottom water in the vicinity of the artificial dyke and net cage aquaculture site in summer. Annual mean of DO was 8.4 mg/l, with minimum monthly mean of 6.9 mg/l in July and maximum of 11.2 mg/l in March. Temporal variation of DO at bottom water around the net cage aquaculture site shows pronounced oscillatory characteristics with range of 0.5~7.0 mg/l. Coherency analyses between the tidal range and DO concentration shows that variation of DO is significantly coherent with tidal range at semi-diurnal period with 1~3.5 hours phase-lags. A simple DO budget model was set up to account for the formation of the extreme hypoxic conditions in Chunsu Bay. The governing equation is based on the mass-balance for kinetic process with simplified parameter of source and sink terms of DO. the source term is represented by replenishment through the vertical and horizontal diffusion and mixing. the sink terms comprise function of sediment oxygen demand (SOD) and carbonaceous biochemical oxygen demand (CBOD). The result of numerical solution indicates the dominant role of SOD as the overriding factor against the oxygen supply.