• Journal of Navigation and Port Research
• /
• v.30 no.10 s.116
• /
• pp.869-875
• /
• 2006

This paper presents the method for developing an optimum hull form with minimum wave resistance using SQP(sequential quadratic programming) as an optimization technique. The wave resistance is evaluated by a Rankine source panel method with non-linear free surface conditions and the ITTC 1957 friction line is used to predict the frictional resistance coefficient. The geometry of the hull surface is represented and modified using NURBS(Non-Uniform Rational B-Spline) surface patches. To verity the validity of the developed program the numerical calculations for Wigley hull and Series 60( $C_B=0.6$) hull have been performed and the results obtained by the numerical calculations have been compared with the original hulls.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• v.29 no.1
• /
• pp.47-53
• /
• 2005

This paper presents the method for developing an optimum hull form with minimum wave resistance using SQP(sequential quadratic programming) as an optimization technique. The wave resistance is evaluated by a Rankine source panel method with non-linear free surface conditions and the ITTC 1957 friction line is used to predict the frictional resistance coefficient. The geometry of the hull surface is represented and modified using NURBS(Non-Uniform Rational B-Spline) surface patches. To verity the validity of the developed program the numerical calculations for Wigley hull and Series 60(C${_B}$=0.6) hull had been performed and the results obtained after the numerical calculations had been compared with the original hulls.

• Journal of Korea Ship Safrty Technology Authority
• /
• s.37
• /
• pp.24-34
• /
• 2014

최근 몇 년간 국내 해양레저에 대한 관심 증가에 따라, 정부와 지자체의 해양레저산업에 대한 연구 지원 및 마리나 구축 사업 수행 등 해양레저 수요를 수용할 수 있도록 장비 및 시설 확보를 위하여 다양한 방면으로 노력이 한창이다. 그러나 아직까지 국내의 해양레저를 위한 시설 구축은 진행단계이다. 전국적으로 마리나 구축을 위한 작업이 한창이며, 이미 구축된 마리나에서 요트를 계류할 경우 관리하는데 드는 비용이 만만치 않아 사용자에겐 부담이 크다. 세일링 요트의 경우 span이 큰 모노킬이 부착되어있으므로 마리나 혹은 육상계류시설을 이용하지 않을시 모노킬이 파손될 위험이 있다. 본 연구에서는 서해안의 해양레저 대중화를 위해 누구나 안전하게 세일링을 즐길 수 있고, 두 개의 킬로 선체를 지지하여 육상 및 갯벌에서도 선체가 기울지 않고 설 수 있는 트윈킬 요트를 개발하여 보급하고자 한다. 기존 세일링 요트중 성능이 좋은 편인 야마하에서 제작한 블루워터21의 선형을 활용하였고 트윈킬은 블루워터21 모노킬의 면적 및 무게중심 등을 분석하여 개발하였다. 트윈킬 요트의 경우 모노킬 요트보다는 저항성능이 불리할 것으로 예상되므로 모형시험을 수행하였으며, 그 결과 모노킬과 트윈킬의 저항성능에 대한 차이가 예상보다 크지 않음을 확인하였다.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.20 no.4
• /
• pp.426-434
• /
• 2014

The research developed twin keel yacht for everyone which is able to stand erectly on mud flat without list and intended to commercialize the development product for popularization of west coast's marine leisure industry. Yacht's linear was utilized by "Blue Water21" has superior performance among the existing sailing yachts and twin keel model has been tested by calculation of mono keel's extent and its center of gravity. The result was that only 4 % of difference have been identified between mono keel and twin keel's hydrodynamic resistance which was smaller difference than predicted.

• Journal of the Society of Naval Architects of Korea
• /
• v.57 no.5
• /
• pp.278-286
• /
• 2020

Reynolds-averaged Navier-Stokes simulations have been performed to investigate an effect of numerical region with high resolution for Kelvin wave around KRISO container ship on its resistance. In the present study, 13 millions cells were used to describe wave profile along the ship hull and Kelvin wave patterns. In order to control a size of numerical region with high resolution for waves around the hull, we employed relaxation zones from a side boundary of numerical domain in which Kelvin wave was suppressed. When the far-field Kelvin wave was not precisely resolved due to the relaxation zone, the instantaneous history of ship resistance was affected although the time average of ship resistance showed -1.15~2.1 % errors. Especially, the damping characteristics of ship resistance in time history was significant when using a large relaxation zone in the side boundary.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.32 no.1
• /
• pp.21-27
• /
• 1995

초고속선에 관련된 점성유동은 저한성능 향상과 운항자세 제어를 위해 사용되는 다양한 선체부 가물의 저항 예측과 초고속선에 많이 사용되는 물분사 추진장치 입구 형상의 설계 그리고 임펠 러에 이르는 덕트 유동의 예측을 중심으로 관심을 받아왔다. 본 소고에서는 통상적인 선박의 경우와는 구별되는 초고속선 고유의 점성유동 특성에 관하여 간략히 논의하기로 하고 내용을 크게 선체-부가물 점성유동과 물분사 추진장치에 관련되어 있는 덕트유동으로 나누어 기술하 였다.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.28 no.7
• /
• pp.1274-1280
• /
• 2022

The resistance performance evaluation of general ships using computational fluid dynamics requires a lot of time and cost, and various methods are being studied to reduce the time and cost. Existing methods using main particulars or cross sections of ships have limitations in estimating resistance performance that is greatly dependent on the shape of the ship. In this paper, we propose a deep neural network model that can quickly predict the resistance performance of the hull surface by inputting the geometric information of the hullform mesh. The proposed deep neural network model based on Perceiver IO can immediately predict resistance performance, unlike computational fluid dynamics techniques that require calculation in each time step. It shows the result of estimating the resistance performance with an average error of less than 1% in the data set for a 50 K tanker ship, a type of low-speed full ship.

• Journal of Navigation and Port Research
• /
• v.38 no.4
• /
• pp.335-341
• /
• 2014

Faced with global agenda of greenhouse abatement program including regulations and $CO_2$ emission trading scheme, shipping companies are enforced to a high level of efficiency in fuel consumption. Accordingly shipbuilding companies worldwide are required to develop fuel-efficient ships which otherwise traditionally consume a great amount of fossil fuels. In this dissertation, relevant to the improvement of fuel efficiency for commercial ships, design methodology through the numerical simulations are intensively described. This work consists of derivation of effective hydrodynamic design practice based on the application of longitudinal grooves to effectively improve the pressure distribution around ship hull. The primary objective of the present study is to improve ship resistance performance using longitudinal grooves which originate from long strips on the abdomen of humpback whale. Several groove shapes have been extensively investigated and the proposed shape efficiently controlled the variation of pressure distributions acting on the hull surface.

• Journal of the Society of Naval Architects of Korea
• /
• v.54 no.3
• /
• pp.258-266
• /
• 2017

Numerical simulations of turbulent two phase flows around KCS have been performed to investigate effects of trim conditions on ship resistance of KCS in short waves by utilizing waves2foam. The wave lengths of LPP/2 and LPP/4 with 1m and 2m wave heights were imposed at inlet boundary. The resistance reduction at 2m trim by head and the increase of resistance at trims by stern were observed regardless of wave lengths and wave heights. The hull pressure on fore-and-aft rather than wave patterns around bulbous bows was mainly responsible for the total resistance coefficients of KCS in short waves. A phase diagram of contribution of hull pressure to the total resistance coefficients disclosed that the phase of representing the maximum resistance in time history played an important role in the effect of trim conditions on ship resistance of KCS in short waves.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2019.11a
• /
• pp.270-270
• /
• 2019

Although the Inertial Measurement Unit is applied to a variety of applications such as ships, submarines, and aircrafts, it is mainly used in the attitude measurement area. But since such equipment is expensive, it has been used only in special fields. In this study, the ship's seaworthiness is verified by measuring the speed, direction, gravity, and acceleration of the ship in real time using a low-cost Inertial Measurement Unit. A research method for estimating fIuid force coefficients was devised. Therefore, this study measured ship motion factors at sea, processed and analyzed the measured data, and evaluated the overall safety of the ship and estimated the resistance and steering performance of the ship.