• 한국항해항만학회지
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• 제46권3호
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• pp.168-178
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• 2022

본 연구에서는 선수부에 프로펠러를 갖는 수중운동체의 연직면 조종성능을 추정하기 위해 저항시험, 연직면 사항시험, VPMM 시험을 부산대학교 예인수조에서 수행하였다. 연직면 사항시험은 대각도에서 발생하는 횡교차력 성분을 고려하기 위해 -40도에서 40도 범위 내에서 수행하였다. 프로펠러의 회전 상태는 특정 rpm으로 회전하는 경우와 예인속도에 맞춰 자연스럽게 프로펠러가 회전하는 경우로 나눠 시험을 수행하였다. 구속모형 시험을 통해 수중운동체의 연직면 조종 유체력 미계수를 추정하였으며 최종적으로 동유체력 미계수를 기반으로 연직면 동적 안정성지수를 산정하고 프로펠러 회전 상태가 동적 안정성에 미치는 영향을 분석하였다. 본 시험 결과는 전방에 프로펠러를 갖는 수중운동체의 조종시험 참고자료로서 활용될 것으로 기대된다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2016년도 춘계학술대회
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• pp.78-80
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• 2016

선박이 천수 영역에서 운항할 때, 선저부분의 압력변화로 인하여 흘수가 증가하는 현상이 나타난다. 이 같은 현상을 선체침하(Squat)라 하며, 선박의 조종성능을 변화시켜 해양사고의 발생위험을 높이게 된다. 특히, 초대형 선박의 경우에는 흘수가 커 천수영역에서의 선체침하현상이 더욱 크게 일어난다. 따라서 본 연구에서는 천수 영역에서의 초대형선박의 선체침하정도를 추정하고자 하였다. 이를 위하여, 세 가지 천수조건을 구성하고, 다양한 추정식을 이용하여 초대형선박의 경사각도에 따른 선체 침하의 정도를 계산하였으며, 그 결과를 비교하여 보여주었다.

• 한국해양공학회지
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• 제16권6호
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• pp.25-31
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• 2002

A system identification method is introduced to increase the prediction accuracy of a ship's maneuverability in PMM test, analysis. To improve the accuracy of linear hydrodynamic coefficients, the analysis techniques of pure sway and yaw tests are developed, and confirmed. In the analysis of sway tests, accuracy to linear hydrodynamic coefficients depends on the frequency of sway motion. To obtain nonlinear hydrodynamic coefficients for large drift angles, a combined yaw test is introduced. Using this system identification method, runs of PMM test can be reduced while retaining sufficient accuracy, compared to the Fourier integration method. Through the comparisons with sea trial results and the Fourier integration method, the accuracy and efficiency of the newly proposed system identification method, based on least square method, has been validated.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2023년도 춘계학술대회
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• pp.151-151
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• 2023

무인잠수정의 정밀한 제어 시스템 개발에는 높은 정도의 조종 유체력 미계수 추정이 필수적이다. 전통적으로 조종 미계수는 모형을 이용한 실험(사항, Planar Motion Mechanism, Rotating Arm)과 단순한 이론과 경험을 기반으로 개발된 경험식으로 추정하였다. 그러나 최근 크게 향상된 계산기 성능의 발전은 전산유체역학의 적용성을 크게 확대하였다. 따라서 본 논문에서는 만타형 무인잠수정의 조종 유체력 미계수 추정을 위한 전산유체역학 해석기법을 개발하고자 한다. 특히, 수직 동적 PMM 시험법에 관한 해석기법을 중점적으로 개발한다. 개발된 기법을 이용하여 만타형 무인 잠수정의 6자유도 유체력을 추정하고 그 결과를 실험과 비교하여 개발된 기법을 검증한다. 본 연구에서는 1/6 모형을 이용한다. 수치해석기법 개발은 RASN 기반 상용 해석소프트웨어인 STAR-CCM+를 사용하였다.

• 대한조선학회논문집
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• 제37권2호
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• pp.88-99
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• 2000

선박의 조종성능 추정 및 향상을 위한 이론적, 실험적 연구의 일환으로 최적방향타 설계를 위한 실험적 연구를 수행하였다. 본 연구는 크게 보아 방향타의 성능을 결정짓는 세 가지 주요특성, 즉 단면형상, 투영형상 및 가로세로비(aspect ratio)에 대한 연구와 특수단면형상에 대한 연구로 구성되어 있으며 각각의 특성에 대하여 실용적으로 유용한 설계방향 및 결론을 도출하였다. 특히 특수단면 형상중 돌고래꼬리형 단면형상(dolphin-tail type section shape)은 방향타의 단면으로 사용될 경우 방향타의 성능을 현저히 향상시킬 수 있는 가능성이 있음을 보여주고 있다.

• 대한조선학회논문집
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• 제54권4호
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• pp.275-285
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• 2017

In order to predict the sailing performance of a LNGC during actual operation, it is necessary to consider not only the information about resistance, maneuverability etc. but also the information such as sea route and sailing scenario etc., comprehensively. In this paper, we propose a new approach to conduct the sailing simulation of a LNGC without full scale measurement data. Latitude, longitude, sea route, speed over ground, time in UTC obtained from AIS data are substituted for the measured data. By combining the model test results, design information, and AIS data, prediction of sailing performance is conducted from the coast of southern Taiwan to the coast of Madagascar. The simulation is verified by comparing the calculated time histories of RPM and power with those of measured RPM and power.

• 대한조선학회논문집
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• 제55권4호
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• pp.350-360
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• 2018

Analysis of ship's manoeuverability in shallow water is an important task from the perspective of the vessels' navigational safety. Since the number of ships operated in restricted water has increased due to the enlargement of vessels and ships represent different characteristics of the manoeuverability when operated in shallow and deep water, it is significant to evaluate ship manoeuverability at initial design stage. At the initial stage of design, the estimation of manoeuverability is generally performed with hydrodynamic coefficients estimated based on empirical formula. However, the accuracy of estimating hydrodynamic coefficients by the empirical formula in shallow water is poor compared to that in deep water. Therefore, the error in the estimation of manoeuverability increases in shallow water. In this study, CFD is proposed to improve the accuracy of manoeuverability in shallow water at the initial design stage and hydrodynamic coefficients were obtained based on PMM test in shallow water. Furthermore, the ship manoeuverability was estimated both the proposed strategy and the empirical formula. At last, validity of the proposed strategy using CFD for the estimation of manoeuverability was confirmed by comparison with the manoeuverability estimation results from model test.

• 대한조선학회논문집
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• 제57권5호
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• pp.287-296
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• 2020

The present study aims to improve the accuracy of the maneuvering simulations based on captive model test results. To derive the hydrodynamic coefficients in a self-propelled condition, a mathematical maneuvering model using a whole vehicle model was established. Captive model tests were carried out using the Vertical Planar Motion Mechanism (VPMM) equipment. A motor controller was used to control the constant propeller revolution rate during pure motion tests. The resistance tests, self-propulsion tests, static drift tests, and VPMM tests were performed in the towing tank of Seoul National University. When the vertical drift angle changes, the gravity load on the sensors were changed. The hydrodynamic forces were deduced by subtracting the gravity load from the measured forces. The hydrodynamic coefficients were calculated using the least-square method. The simulation of the turning circle test was compared with the free-running model test result, and the error of the turning radius was 8.3 % compared to the free-running model test.

• 대한조선학회논문집
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• 제41권4호
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• pp.53-58
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• 2004

When a fast container ship or a naval vessel is turning, comparable roll motions occur. Therefore, roll effect has to be considered in the horizontal equations of motion of the ship to predict the maneuverability well. In this thesis, a new method to determine a roll model structure and estimate its coefficients by applying the system identification technique to the data of sea trial tests was proposed. The simulation results from the estimated roll model were well consistent with the true one in spite of the difference between the estimated and the true model structures of roll hydrodynamic moment.

• 대한조선학회논문집
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• 제45권3호
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• pp.280-287
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• 2008

In this paper, a mathematical model for a ship manoeuvring with low forward speed in shallow water was suggested. Based on the cross flow model with low forward speed in deep sea, hull, propeller and rudder models were modified to consider the shallow water effects. Static drift and PMM tests were performed to obtain the cross flow drag coefficients and hydrodynamic coefficients. To validate suggested mathematical model, numerical simulation results were compared with those of sea-trials. Through comparisons, it was concluded that suggested mathematical model could give proper estimation on turning test results.