• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 추계학술대회 논문집(제2권)
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• pp.13-17
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• 2006

Almost every day close passage or near miss events happens in south part of Istanbul Strait between the vessel runs in the local area and pass strait transit. The vessels run in the local area pass close bow or aft of transit vessel or come close and wait for transit vessel because of inexperienced or incompetent skipper or because of time limitation or failure in technical equipment or lack of technical equipment or old equipment. This close passages create profound dangers for the surroundings. By the this research has been aimed to point out mentioned dangers by the concrete as number. For this purpose has been utilized JMS Ship Handling Simulator which has been settled in ITU Maritime Faculty and Environmental Stress Model which has been built up and improved in Inoue Laboratory. Has been put in the senarios which been played during simulation implementations transferred to the numerical risk occured during passage of South Part of Istanbul Strait by the Environmental Stress Model . Thus so, the riskwhich Istanbul Strait face everyday has been expressed as numerical and concrete.

• 자동차안전학회지
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• 제11권4호
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• pp.57-62
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• 2019

The seat back frame of the vehicle is subjected to load on the passenger behavior. Because of steel material, it is necessary to optimize the frame considering lightweight and safety. In this paper, finite element analysis is used for the optimal design of the seat back frame. First, a lightweight material is applied to reduce the weight of the seat back frame. Secondly, the design position of the pipe part fastened in the seat back frame was selected by considering the strength against the load generated by the occupant. Third, the shape of the side frame was derived by performing the phase optimization analysis for the AFT load condition. And we have compared the initial model with the optimal model to verify the light weighting and safety. As a result, the optimal design model of the seat back frame satisfying the weight reduction and safety has been proposed.

• 한국해양공학회지
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• 제13권2호통권32호
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• pp.138-146
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• 1999

The viscous flow around a ship hull is calculated by the use of RANS(Reynolds-averaged Navier-Stokes) solver. Reynolds stresses are midelled by using the k-${epsilon}$ turbulence model and the law is applied near the body. Body fitted corrdinates are introduced for the treatment of the complex boundary of the ship hull form and the governing equations in the physical domain transformed into ones in the computational domain. The transformed equations are numerically solved by an employment of FVM(Finite Volume Method). SIMPLE(Semi-Implicit Pressure Linked Equation) method is adopted in the calculation of pressure and the solution of the sidcretized equation is obtained by the line-by-line method with the use of TDMA(Tri-Diagonal Matrix Algorithme). To assure the proprietty of this computing method, HSVA tanker and Dyne hull are calculated ar both model and ship scale Reynolds number. Their reaults of pressure distributions on fore and aft body, axial velocity contours and transverse velocity velocity vectors and viscous resistance coefficients are compared with other's experiments and calculations.

• 해양환경안전학회지
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• 제16권4호
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• pp.401-406
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• 2010

해상에서의 선박운항자는 선박을 운항 중 장애물 혹은 타선에 대하여 적정한 이격거리를 두고 항행하고 있다. 다시 말해 시정 상태, 풍속, 조류 등에 따라 선박 전 후 거리, 좌 우현 정횡거리를 주관적인 안전 의식에 근거하여 이격하여 통항하고 있다. 현재 우리나라에서는 통항 선박 간 최소 안전이격거리 개념을 1980년대 초 외국에서 조사된 자료로 사용하고 있고, 항계 내(제한수로)와 항계 밖의 통항 선박의 안전거리가 상이함에도 불구하고 구분 없이 사용되고 있다. 또한 선박 조종학적 안전거리는 선박 전후 거리보다는 선박 측면거리가 중심이며, 선박 종류에 따라 최소 안전이격거리가 상이하지만 고려되고 있지 않은 실정이다. 따라서 이 논문에서는 상황에 따른 선박운항자의 안전 의식을 고려한 적정 이격거리를 정량화하여 해상교통안전성 평가모델의 충돌 판정 영역 개발을 위한 기초 자료로 활용하고자 하고, 우리나라에 적합한 해상교통 혼잡도 모델 개발 및 상황 선박별 해상교통관제에 필요한 가이드라인으로 이용할 수 있는 기초자료를 제공하는 데 목적이 있다. 연구결과, 시정이 양호한 주간의 경우 선수전방 4.4 L, 선미후방 3.1 L, 정횡 2.6L로 기존에 사용되고 있는 최소 안전이격거리와는 차이가 있는 것으로 분석되었으며 시정 및 주야간 등과 같은 파라미터를 다양하게 고려하였다.

• 대한토목학회논문집
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• 제30권4D호
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• pp.323-330
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• 2010

선박의 항구 내 재항시간은 대상항구의 운영상태 파악 및 장래 규모 산정을 위해 중요한 요인이다. 재항시간을 분석하기 위해 다양한 연구들이 시도되어 왔으나 선박의 재항시간에 영향을 미치는 요인들의 효과를 통계적 분석을 통해 추정한 연구는 미흡한 실정이다. 특히 선박의 항구 내 재항시간은 항구 내에서 발생하는 대기오염물질 및 온실가스 배출량과 직접적인 영향이 있는 바 본 연구에서는 2008년 부산항에 입항한 외항선박(19,167척)의 재항시간을 모수적 생존분석 기법을 통해 분석하였다. 이를 위해 로그-정규 가속화시간(AFT: accelerated failure time)모형과 로그-로지스틱 AFT모형이 추정되었으며, 추정결과 재항시간은 부두의 서비스 용량, 선박의 총중량, 선박의 종류에 유의한 영향을 받는 것으로 나타났다(${\alpha}$=0.05). 추정된 재항시간, 선박별 운항시간, 연료소비량 추정치를 이용하여 선박종류별 온실가스 배출량을 산정하였으며, 그 결과 2008년 부산항에 양적하 및 여객수송 목적으로 입항한 선박의 61%를 차지하는 풀컨테이너선의 부산항계 내 온실가스 배출량은 약 "17톤/회",로 나타났다. 그러나 2008년 부산항 입항선박의 약 20%를 차지하는 컨테이너선 외 화물운송선박의 정박 시 온실가스 배출량(톤/회)은 풀컨테이너선의 온실가스 배출량(톤/회)보다 크게 나타나, 해당 선박이 취급하는 화물의 양적하 시간 및 접안대기시간을 감소시킬 수 있는 물류 처리 기술 및 항만운영 정책 도입이 필요한 것으로 나타났다.

• Journal of Ship and Ocean Technology
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• 제4권1호
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• pp.11-20
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• 2000

Reynolds-averaged Navier-Stokes equations are numerically solved using a secondorder finite difference method for the analysis of turbulent flows around single and tandem hydrofoils advancing under the free surface. The location of the free surface, not known a priori, is computed from the kinematic free surface condition and the computational grid is conformed at each iteration to the free surface deformation. The eddy viscosity model of Baldwin-Lomax is employed for the turbulence closure. The method is validated through the comparision of the numerical results with the experimental data for a single hydrofoil of a Joukowski foil section. A computational study is also carried out to investigate the effect of the submergence depth and the Froude number on the lift and the drag of the hydrofoil. For tandem hydrofoils, computations are performed for several separation distances between the forward and aft foils to see the interference effect. The result shows clearly how the lift and drag change with the separation distance.

• 대한기계학회논문집B
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• 제27권7호
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• pp.883-892
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• 2003

The experiment using three-dimensional laser Dopperr velocimetery (LDV) measurements and the computation using the Reynolds stress model of the commercial code, FLUENT, were conducted to give a clear understanding on the structure of tip leakage flow in a forward-swept axial-flow fan operating at the maximum efficiency condition. The tip leakage vortex was generated near the position of the minimum wall static pressure, which was located at approximately 12% chord downstream from the leading edge of blade suction side, and developed along the centerline of the pressure trough within the blade passages. A reverse flow between the blade tip region and the casing, induced by tip leakage vortex, acted as a blockage on the through-flow. As a result, high momentum flux was observed below the tip leakage vortex. As the tip leakage vortex proceeded to the aft part of the blade passage, the strength of tip leakage vortex decreased due to the strong interaction with the through-flow and casing boundary layer, and the diffusion of tip leakage vortex caused by high turbulence. In comparison with LDV measurement data, the computed results predicted the complex viscous flow patterns inside the tip region, including the locus of tip leakage vortex center, in a reliable level.

• 대한조선학회논문집
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• 제52권1호
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• pp.61-69
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• 2015

In the beginning of the 1990's, numerous shaft bearing damages, especially in aft stern tube bearing, were reported. The main reasons of bearing damages were estimated that hull deflections have been increased by more flexible hulls and propeller dynamic loads have not been considered in shaft alignment. After that time, studies to take into account hull deflections in shaft alignment have been actively carried out, but for the latter leave much to be desired. In this study, the effects of the propeller forces on the propeller shaft bearing have been investigated by estimating thrust eccentricity as reasonable as possible although some assumptions to simulate turning of ship were introduced. Three dimensional nominal wake to estimate thrust eccentricity have been calculated by using CFD analysis and model test in the towing tank. This study presents the procedure to estimate the propeller eccentric forces and their influence on the stern tube bearing for a container carrier. As a result, it has been found that the lateral propeller forces in turning condition should be considered in shaft alignment to prevent shaft bearing damages.

• Asian Pacific Journal of Cancer Prevention
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• 제13권5호
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• pp.1829-1831
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• 2012

Background: The generalized gamma distribution statistics constitute an extensive family that contains nearly all of the most commonly used distributions including the exponential, Weibull and log normal. A saturated version of the model allows covariates having effects through all the parameters of survival time distribution. Accelerated failure-time models assume that only one parameter of the distribution depends on the covariates. Methods: We fitted both the conventional GG model and the saturated form for each of its members including the Weibull and lognormal distribution; and compared them using likelihood ratios. To compare the selected parameter distribution with log logistic distribution which is a famous distribution in survival analysis that is not included in generalized gamma family, we used the Akaike information criterion (AIC; r=l(b)-2p). All models were fitted using data for 369 women age 50 years or more, diagnosed with stage IV breast cancer in BC during 1990-1999 and followed to 2010. Results: In both conventional and saturated parametric models, the lognormal was the best candidate among the GG family members; also, the lognormal fitted better than log-logistic distribution. By the conventional GG model, the variables "surgery", "radiotherapy", "hormone therapy", "erposneg" and interaction between "hormone therapy" and "erposneg" are significant. In the AFT model, we estimated the relative time for these variables. By the saturated GG model, similar significant variables are selected. Estimating the relative times in different percentiles of extended model illustrate the pattern in which the relative survival time change during the time. Conclusions: The advantage of using the generalized gamma distribution is that it facilitates estimating a model with improved fit over the standard Weibull or lognormal distributions. Alternatively, the generalized F family of distributions might be considered, of which the generalized gamma distribution is a member and also includes the commonly used log-logistic distribution.

• 대한조선학회지
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• 제4권1호
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• pp.49-54
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• 1967

The authors considered the effects of trim in the small coastal passenger boat upon resistance in this paper. Any change of trim no matter how small, necessarily produces some effect upon resistance. The relations between the resistance coefficients and trim were investigated through the towing test of the Model $MCI-P_1-65$, Korean Standardized Ship, GT 70 tons passenger boat in the gravitational tank. The Lines of the Model are given in Fig. 1. Principal dimensions and other characteristics vary with the trim in general. Those values varied with the trim for $MCI-P_1-65$ are tabulated in table 1. The resistance was measured at five conditions such as even keel, 0.0273L, (original designed trim) 0.0473L, 0.0663L, 0.0873L trim by the stern, fixing the displacement corresponding to the designed load water line. Model was made of wood in length of 3.5 feet coated with varnish, and without appendages. As the artificial turbulent stimulator, the sand strip method was used. The results of model towing tests, correcting to water temperature of $70^{\circ}F$, were expanded to full scale using the Schoenherr's friction formula and surface roughness allowance coefficient of 0.0004. The authors point out, the following results. 1) Optimum trim which gives the minimum resistance exists for every speed at constant displacement and each comes to the same value. For $MCI-P_1-65$ optimum trim is 0.0673L trim by the stern(Fig.4-The cross curves of the resistancecoefficients). 2) At constant displacement, when LCB(longitudinal position of center of buoyancy) varies with the trim, there exists optimum value of LCB which gives minimum resistance for every speed and each comes to the same value. For $MCI-P_1-65$ optimum position of LCB is 8%L aft from midship section (Fig.6).