• International Journal of Ocean System Engineering
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• 제3권2호
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• pp.77-89
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• 2013

The propeller performance has been investigated using a benchmark Duisburg Test Case ship with RANSE. First, the hydrodynamic characteristics of propeller in case of open water have been analyzed by a commercial CFD program and the results are compared with those of experimental data. Later, the flow around the bare hull has been solved and the frictional resistance value and form factor of the ship have been obtained and compared with those of ITTC57 formulation and experimental results for validation. The free surface effect has been ignored. A good agreement has been obtained between the results of RANSE and experiments at both stages. Then the ship - propeller interaction problem was solved by RANSE and the differences in thrust, torque and efficiency of propeller as compared with the open-water numerical results have been discussed.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권1호
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• pp.25-40
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• 2015

Understanding the effects of the parameters affecting the interaction of tandem hydrofoil system is a crucial subject in order to fully comprehend the aero/hydrodynamics of any vehicle moving inside a fluid. This study covers a parametric study on tandem hydrofoil interaction in both potential and viscous fluids using iterative Boundary Element Method (BEM) and RANSE. BEM allows a quick estimation of the flow around bodies and may be used for practical purposes to assess the interaction inside the fluid. The produced results are verified by conformal mapping and Finite Volume Method (FVM). RANSE is used for viscous flow conditions to assess the effects of viscosity compared to the inviscid solutions proposed by BEM. Six different parameters are investigated and they are the effects of distance, thickness, angle of attack, chord length, aspect ratio and tapered wings. A generalized 2-D code is developed implementing the iterative procedure and is adapted to generate results. Effects of free surface and cavitation are ignored. It is believed that the present work will provide insight into the parametric interference between hydrofoils inside the fluid.

• International Journal of Naval Architecture and Ocean Engineering
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• 제4권3호
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• pp.322-334
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• 2012

This paper shows the numerical and experimental results about the hydrodynamic characteristics of X-Twisted rudders having continuous twist of the leading edge along the span. All the results were compared with those of the semi-balanced rudder. Calculation through the Reynolds-Averaged Navier-Stokes Equation (RANSE) code with propeller sliding meshes shows large inflow angle and fast inflow velocity in the vicinity of ${\pm}0.7$ R from the shaft center, so it may cause cavitation. Also, X-Twisted rudder has relatively small inflow angles along the rudder span compared with semi-balanced rudder. For the performance validation, rudders for two large container carriers were designed and tested. Cavitation tests at the medium sized cavitation tunnel with respect to the rudder types and twisted angles showed the effectiveness of twist on cavitation and the tendency according to the twist. And the resistance, self-propulsion and manoeuvring tests were also carried out at the towing tank. As a result, in the case of X-Twisted rudder, ship speed was improved with good manoeuvring performance. Especially, it was found out that manoeuvring performance between port and starboard was well balanced compared with semi-balanced rudders.

• Journal of Pharmaceutical Investigation
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• 제19권4호
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• pp.203-212
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• 1989

A proteolytic enzyme was extracted from Sarcodon aspratus (Berk) S. Ito by percolation method. Proteolytic activity of the extracted proteolytic enzyme (SAP) was compared with several digestives containing proteolytic enzymes. Potency of SAP was higher than that of the other digestives except for protease. The optimum pH ranse of SAP was similar to that of pancveatin and protease. SAP was more stable than pancreatin and protease under various temperature, alkaline pH, and metal ions. Bovine serum albumin hydrolysing activity of SAP was equivalent to that of pancreatin and protease in small intestine of rats. SAP demonstrated lower adsorption to antacids than pancreatin and protease. Among the mixtures of SAP and several antacids, magnesium oxide-SAP showed the highest proteolytic activity.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권2호
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• pp.149-159
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• 2017

In this study, the numerical investigation of ship motions and added resistance at constant forward velocity of KVLCC2 model is presented. Finite volume CFD code is used to calculate three dimensional, incompressible, unsteady RANS equations. Numerical computations show that reliable numerical results can be obtained in head waves. In the numerical analyses, body attached mesh method is used to simulate the ship motions. Free surface is simulated by using VOF method. The relationship between the turbulence viscosity and the velocities are obtained through the standard ${\kappa}-{\varepsilon}$ turbulence model. The numerical results are examined in terms of ship resistance, ship motions and added resistance. The validation studies are carried out by comparing the present results obtained for the KVLCC2 hull from the literature. It is shown that, ship resistance, pitch and heave motions in regular head waves can be estimated accurately, although, added resistance can be predicted with some error.

• 한국응용과학기술학회지
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• 제38권2호
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• pp.378-388
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• 2021

본 연구는 중년여성의 자아탄력성, 부부의사소통, 정신건강이 행복감에 미치는 영향을 확인하기 위하여 수행되었다. 본 연구에 참여한 연구대상자는 239명으로, 평균연령은 54.15±6.38세 이었다. 연구분석 방법은 SPSS 21.0을 사용하여 일반적 특성에 따른 제 변수간의 차이, 자아탄력성, 부부의사소통, 정신건강, 행복감의 상관관계를 확인하였고, 중년여성의 행복감에 영향을 미치는 요인을 확인하기 위해 다중회귀분석을 실시하였다. 연구결과 자아탄력성 평균 3.46점((1-5점), 부부의사소통 평균 2.44점(1-5점), 정신건강 평균 1.82점(0-4점), 행복감 3,21점(1-5점)으로 나타났다. 일반적 특성에서 행복감의 차이는 교육수준(F=3.406, p=.035), 주관적 건강상태(F=7.385, p=.001)에서 통계적으로 유의한 차이를 보였다. 제 변수들간 상관관계를 확인한 결과 행복감은 자아탄력성(r=.393, p=<.001)은 정적상관관계를 보였고 신체화(r=-.134, p=.039), 우울(r=-.356, p<.001), 불안(r=-.269, p<.001)과는 부적상관 관계를 보였다. 중년여성의 행복감에 영향을 미치는 예측요인은 우울(β=-.437, p<.001)자아탄력성(β=.350, p<.001), 신체화(β=.239 p=.009), 건강상태: 보통(β=-.150, p=.009), 나쁨(β=-.147, p=.015)로 30.4%의 설명력을 보였고, 회귀모형은 통계적으로 유의하게 나타났다(F=14.02, p<.001). 본 연구 결과를 바탕으로 중년여성의 행복감을 증진시키기 위해 자아탄력성을 증진시키고 정신건강을 강화하는 교육 프로그램이 개발되어야 할 것이다.