• Journal of Ship and Ocean Technology
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• 제8권2호
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• pp.29-40
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• 2004

Interaction of grounded ice ridges with underlying seabed is one of the major considerations in the design of Arctic pipeline system. Previously several ice scour models were developed by researchers to describe the ice scour-seabed interaction mechanism. In this paper, a parametric study on ice scouring mechanism is performed and the limitation of ice scour-seabed interaction models is discussed. Simple laboratory tests are carried out and then the shape pattern of deposited soil around the ice is redefined. New ice scour model assumes trapezoidal cross section based on the field observation data. Ice scour depth and soil resistance forces on seabed are calculated with varying the keel angle of a model ice ridge.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.882-883
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• 2007

본 논문에서는 지자계에 노출된 함정의 유도자화에 의한 자기장 성분을 분석하는 방법을 제시하였다. 우선 모델함정을 제작하여 지자계에 노출시킨 상태에서 왕복실험을 수행하고 이때 측정되는 데이터를 수집하여 함정의 수평방향으로 유도되는 자기장성분을 분리하였다. 또한 정밀 수치해석기법을 통해 측정치와 비교함으로서 정밀 수치해석 기법에 의한 예측값의 신뢰성을 확인하였다. 따라서 본 연구결과는 함정 재질 상에 분포하는 유도자화 및 영구자화에 의한 자기장의 거동을 예측함으로서 함정의 자기정숙화(magnetic silent)연구에 중요한 기초 자료로 활용될 것으로 사료된다.

• Ocean Systems Engineering
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• 제9권4호
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• pp.391-407
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• 2019

Tracking the location (position) of a surface or underwater marine vehicle is important as part of guidance and navigation. While the Global Positioning System (GPS) works well in an open sea environment but its use is limited whenever testing scaled-down models of such vehicles in the laboratory environment. This paper presents the design, development and implementation of a low energy ultrasonic augmented single beacon-based localization technique suitable for such requirements. The strategy consists of applying Extended Kalman Filter (EKF) to achieve location tracking from basic dynamic distance measurements of the moving model from a fixed beacon, while on-board motion sensor measures heading angle and velocity. Iterative application of the Extended Kalman Filter yields x and y co-ordinate positions of the moving model. Tests performed on a free-running ship model in a wave basin facility of dimension 30 m by 30 m by 3 m water depth validate the proposed model. The test results show quick convergence with an error of few centimeters in the estimated position of the ship model. The proposed technique has application in the real field scenario by replacing the ultrasonic sensor with industrial grade long range acoustic modem. As compared with the existing systems such as LBL, SBL, USBL and others localization techniques, the proposed technique can save deployment cost and also cut the cost on number of acoustic modems involved.

• 한국해양공학회지
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• 제21권4호
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• pp.8-14
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• 2007

A particle method recognized as one of gridless methods has been developed to investigate incompressible viscous flaw. The method is more feasible and effective than conventional grid methods for solving the flaw field with complicated boundary shapes or multiple bodies. The method is consists of particle interaction models representing pressure gradient, diffusion, incompressibility and the boundary conditions. In the present study, the models in case of various simulation condition were checked with the analytic solution, and applied to the two-dimensional Poiseuille flow in order to validate the developed method.

• 대한조선학회논문집
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• 제50권6호
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• pp.383-389
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• 2013

Analysis and review of survivability is one of the most important aspects when naval vessels are designed. Because aiming points of threat towards the naval vessels in the battle field could not be estimated exactly, probabilistic and statistic approach is frequently introduced to evaluate and enhance the vessel survivability. Some commercial survivability analysis programs are used to perform the analysis for enhancement of susceptibility, vulnerability and recoverability but, they are usually classified and impossible to be exported to other countries because of their national security. In this paper, a simplified vulnerability analysis program is developed to evaluate the vulnerability of the warship in aspects of structure, redundancy and its mission capability at the conceptual design stage. To verify the developed program, the analysis results were compared with those of the commercial program MOTISS(Measure of Total Integrated System Survivability).

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2005년도 춘계학술대회 논문집
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• pp.35-40
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• 2005

선박의 조종운동은 선체와 프로펠러 그리고 타의 연성 운동의 결과로서 선박 조종성능을 향상시키기 위해서는 각 요소의 적절한 평가 및 보완이 필요하다. 본 연구에서는 조종성능 향상 기법의 일례로 특수타의 일종인 플랩타 주위의 유동특성을 유동가시화 시험기법과 PIV 해석을 이용하여 알아본다.

• Journal of Ship and Ocean Technology
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• 제12권1호
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• pp.1-15
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• 2008

An edgetone is the discrete tone or narrow-band sound produced by an oscillating free shear layer, impinging on a rigid surface. In this paper, 2-dimensional edgetone to predict the frequency characteristics of the discrete oscillations of a jet-edge feedback cycle is presented using lattice Boltmznan model with 21 bits, which is introduced a flexible specific heat ratio y to simulate diatomic gases like air. The blown jet is given a parabolic inflow profile for the velocity, and the edges consist of wedges with angle 20 degree (for symmetric wedge) and 23 degree (for inclined wedge), respectively. At a stand-off distance w, the edge is inserted along the centerline of the jet, and a sinuous instability wave with real frequency is assumed to be created in the vicinity of the nozzle exit and to propagate towards the downward. Present results presented have shown in capturing small pressure fluctuating resulting from periodic oscillation of the jet around the edge. The pressure fluctuations propagate with the speed of sound. Their interaction with the wedge produces an irrotational feedback field which, near the nozzle exit, is a periodic transverse flow producing the singularities at the nozzle lips. It is found that, as the numerical example, satisfactory simulation results on the edgetone can be obtained for the complex flow-edge interaction mechanism, demonstrating the capability of the lattice Boltzmann model with flexible specific heat ratio to predict flow-induced noises in the ventilating systems of ship.

• 대한조선학회논문집
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• 제37권4호
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• pp.19-30
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• 2000

선수와 선미에 벌브를 가진 현대적인 상선 주위의 난류유동을 해석하기 위해 유한체적법을 이용한 RANS 방정식의 해법이 개발되었다. 복잡한 선수미의 격자계 생성을 위해 다중블록 선체표면 격자계 생성 기법이 도입되었고, 타원형 미분 방정식의 해를 이용하여 O-H 형태의 공간 격자계생성 기법이 이용되었다. 지배방정식의 대류항과 확산항은 각각 QUICK과 중앙차분법을 이용하여 근사되었고, 속도-압력 연성을 위해 SIMPLEC법이 채택되었다. 개발된 방법은 KRISO 3600TEU 컨테이너선에 적용하여 유선가시화 실험 및 반류계측 결과와 비교하였다. 계산 결과는 선수와 선미에 벌브를 가진 현대적인 선형 주위의 유동 해석을 위해서도 이러한 수치계산 방법이 적용될 수 있음을 보여주고 있다.

• Journal of Advanced Marine Engineering and Technology
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• 제38권3호
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• pp.246-252
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• 2014

본논문은 150마력급 선내형 소형 워터제트 추진시스템 개발에 대한 연구이다. 워터제트는 흡입부, 임펠러, 디퓨저(공기확산기), 후진부와 메인 샤프트로 구성되어 있다. 워터제트의 구성품은 사형 주조후 정밀가공을 거쳐 개발하였다. 워터제트 추진기관의 개발은 각각의 부품에 대한 설계-제작-검사의 과정을 거쳐 최종 완성하였으며, 육상 시험 풀에서는 선체의 이동 없이 워터제트의 펌프 특성을 확인한 결과, 최대 37m/s의 유속과 0.29m3/s의 유량을 배출할 수 있는 성능을 확보하였다. 본 연구에서 개발된 워터제트 추진장치를 설치한 21ft 시험선을 사용하여 실증 연구를 수행하였다. 그 결과, 국내 연안에서 시험시 선체무게와 엔진등 기타 부수적인 무게가 대략 1.2ton 가량 이였으며 이 상태에서 엔진회전수 3,700rpm에서 최대시속 45km/h의 운항속도를 기록하였다.

• 한국군사과학기술학회지
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• 제17권3호
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• pp.318-326
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• 2014

The Shipyard Test of Naval Combat System depends on external factors, such as weather conditions and availability of its sensor-weapon, due to the need of on-board sensor-weapon during the test. This paper suggests the Supportive Equipment using virtual simulator for Shipward Test, in case of the unavailability of the on-board sensor-weapon or the test support force(aircraft, surface ship etc.), to pre-check the functions of the combat system as well as to prepare the Shipyard Test. To mock the real sensor-weapon functions as similar as possible, the Supportive Equipment for Shipyard Test was verified by the Verification and Validation process, which is usually performed while developing models in the Modeling & Simulation field.