• 해양환경안전학회지
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• 제13권3호
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• pp.229-234
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• 2007

현재 근해어업은 기피 산업으로 어민들의 고령화 및 감소로 인력을 구하기 어렵고 어로활동을 하기 위해서는 일반적으로 2명 이상이 1조로 작업이 진행된다. 따라서 숙련되지 못한 사람들이 조를 이루어 작업을 할 경우 의사전달에 시차가 생기고 한사람은 배의 조종에 매달리므로 작업의 능률이 떨어진다. 따라서 레저나 소형어선에서 1인이 선박을 조종하면서 작업이나 레저를 즐길 수 있는 선외기의 원격제어 시스템 연구의 필요성이 대두되었다. 본 연구에서는 작업의 효율을 높이고 인력을 절감 할 수 있는 선외기의 원격제어시스템에 관한 연구를 수행하였다. 선외기는 엔진, 조타기, 정 역전 및 중립 기어박스가 하나의 시스템으로 구성되어 있다. 소형 선외기에 이 세 가지의 제어를 직류전동기를 이용하여 위치제어와 속도제어를 하였고, 마이크로컨트롤러를 이용하여 조타기와 엔진회전수 제어를 프로그램화 하여 어민들이 작업을 하면서 동시에 원하는 조종을 할 수 있도록 시스템을 설계 제작하였다. 시운전결과 전속에서 좌 우현 조타 성능이 명령대로 잘 움직였다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제5권2호
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• pp.188-198
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• 2013

In constructing a collision avoidance system, it is important to determine the time for starting collision avoidance maneuver. Many researchers have attempted to formulate various indices by applying a range of techniques. Among these indices, collision risk obtained by combining Distance to the Closest Point of Approach (DCPA) and Time to the Closest Point of Approach (TCPA) information with fuzzy theory is mostly used. However, the collision risk has a limit, in that membership functions of DCPA and TCPA are empirically determined. In addition, the collision risk is not able to consider several critical collision conditions where the target ship fails to take appropriate actions. It is therefore necessary to design a new concept based on logical approaches. In this paper, a collision ratio is proposed, which is the expected ratio of unavoidable paths to total paths under suitably characterized operation conditions. Total paths are determined by considering categories such as action space and methodology of avoidance. The International Regulations for Preventing Collisions at Sea (1972) and collision avoidance rules (2001) are considered to solve the slower ship's dilemma. Different methods which are based on a constant speed model and simulated speed model are used to calculate the relative positions between own ship and target ship. In the simulated speed model, fuzzy control is applied to determination of command rudder angle. At various encounter situations, the time histories of the collision ratio based on the simulated speed model are compared with those based on the constant speed model.

• 한국지능시스템학회논문지
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• 제12권5호
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• pp.417-423
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• 2002

본 논문에서는 자연언어를 이용하는 인간의 학습방법에 기초한 LIBL방법을 선박의 조타 시스템에 적용하여, 항해사의 조타명령과 같은 언어적 지시가 조타수를 경유하여 수행되는 과정을 대체하는 지능형 조타 제어 시스템을 제안하고자 한다. 구체적인 연구방법으로는 조타수의 적절한 조타조작모델을 퍼지추론 규칙을 이용하여 구현하고, 적절한 의미소 및 평가규칙을 제시한 언어지시 기반 학습방법을 선박의 조타시스템에 적용하여, 항해사의 언어지시에 보다 효율적으로 응답하는 지능형 조타기 제어 시스템을 구현한다. 퍼지추론을 이용하여 조타수의 경험을 바탕으로 한 타 조작 모델을 구축하였고, 지능형 조타 시스템을 위한 타각, 방위도달시간, 정상상태의 의미소를 제안하여, 조타수 조작 모델 규칙을 수정하기 위한 평가 규칙을 제시하였다. 또한, 구축된 선박조종 시뮬레이터에 제안된 시스템을 적용하여 그 유효성을 확인하였다.

• 한국해양공학회지
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• 제29권6호
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• pp.418-426
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• 2015

Recently, shipping operators have been making efforts to reduce the fuel cost in various ways, such as trim optimization and bulb re-design. Furthermore, IMO restricts the hydro-dioxide emissions to the environment based on the EEDI (Energy Efficiency Design Index), EEOI (Energy Efficiency Operational Indicator), and SEEMP (Ship Energy Efficiency Management Plan). In particular, ship speed is one of the most important factors for calculating the EEDI, which is based on methods suggested by ITTC (International Towing Tank Conference) or ISO (International Standardization Organization). Many shipbuilding companies in Korea have carried out speed trials around the Korea Straits. However, the conditions for these speed trials have not been exactly the same as those for model tests. Therefore, a ship’s speed is corrected by measured environmental data such as the seawater temperature, density, wind, waves, swell, drift, and rudder angle to match the conditions of the model tests. In this study, fundamental research was performed to evaluate the ship resistance performance due to changes in the water temperature and salinity, comparing the ISO method and numerical simulation. A numerical simulation of a KCS (KRISO Container ship) with a free-surface was performed using the commercial software Star-CCM+ under three conditions that were assumed based on the water temperature and salinity data in the Korea Straits. In the simulation results, the resistance increased under low water temperature & high salinity conditions, and it decreased under high water temperature & low salinity conditions. In addition, the ISO method showed the same result as the simulation.

• 한국항해학회지
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• 제10권2호
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• pp.97-114
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• 1986

Ship's maneuverability is very important factor in safe ship handling and economical ship operation. Steering characteristics are consisted of course stability and maneuverability. Today in many advanced ship-building countries, they study ship's course stability, using model ship tests, such as straight line tests, rotating arm tests and Planar Motion Mechanism (PMM) etc., in tow in tanks. It is the purpose of this paper to provide ship's handlers with better understanding of steering characteristics and to help them in safe controlling and manevering . In this paper, the author simulated response of various vessels, running straight course with constant speed, and they are disturbed by small external disturbance of one degree yaw angle with no angular velocity . The author used the hydrodynamic derivtives resulted at tests of Davidson's laboratory in Stevens Institute of Technology, New Jersey, U.S.A. Course stability was evaluated and analyzed in various respects, such as block coefficient, ratio of ship's length to beam, draft and rudder area ratio etc. The obtained results are as follows : (1) The ship's course stability is affected by magnitude of block coefficient greatly. In case that the block coefficient is more than 0.7, the deviation varies at nearly same rate but the requistite time to reach the steady course is different. (2) The ship's course stability is affected by magnitude of L/B. When the dimensionless time reaches about 3, the deviation and requisite time to reach the steady course are influenced nearly same. After the dimensionless time is about 3, they change on invariable ratio. (3) The effect to course stability by L/T and RA' can be neglected. (4) The reason why thy VLCC and container feeder vessel are unstable on their course is that their block coefficient is generally more than 0.8 and the ratio of ship's length to beam is about 6.0.

• 산업경영시스템학회지
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• 제33권2호
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• pp.154-161
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• 2010

The conning display which is located in the ship bridge shows the various important information such as ship position, ship speed, track data, rate of turn, thruster rpm so on, and is one of the IBSs(Integrated Bridge Systems). In this study, the survey was conducted for ten officers to find the importance and using frequency of the information which were displayed in the conning display. The results showed that the information of drift speed, ship speed, wind direction and wind force, rate of turn, sea water depth, ship position, heading, thrust rpm, alarm, rudder command and angle got high scores and it meant that these information were very important and high frequency of use during the navigation. The optimized contents arrangement in conning display was suggested based on importance and using frequency of information. The experiment using eye-tracking system was conducted to compare the performance time and error rate of nine different scenarios for suggested arrangement display and three other existing displays. The results showed that the suggested arrangement was the best in performance time and error rate. The scenario concerning the direction and speed of wind showed faster performance time and lower error rate than other scenarios. The movement of subject's eye tended to search from the center and to avoid the comer, called 'the comer effect.' It is expected that the results of this study could help for the bridge staff to grasp the sailing information easily and to cope with the given situations promptly.

• 대한조선학회논문집
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• 제36권4호
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• pp.21-27
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• 1999

본 논문에서는 교란 포텐셜을 기저로 하는 패널방법을 사용하여 물제트를 분사하는 플랩을 가진 타의 성능해석을 수행하였다. 받음각이 큰 경우, 성능해석의 주요 인자가 되는 후류면의 위치를 구하기 위하여 후류면의 roll-up을 포함시킨 Pyo[1]의 방법을 사용하여 계산하였고, 경계면은 쌍곡면 패널로 이산화하였다. 플랩타의 본체와 플랩 사이의 간극유동을 점성유동인 Couette유동으로 가정하여 계산하였고, 간극 사이에서 분사되는 물제트는 유량변화를 소스로, 모멘텀변화를 떨어져 나가는 보오텍스로 가정하여, 간극의 입구와 출구 패널 위에서 경계조건으로 포함시켜 계산하였다. 본 방법의 수치적 검증을 위해 실험값이 존재하는 경우에 대해 실험값과 프로그램의 수치결과를 비교하였다. 비교 결과, 실험값은 계산값과 좋은 일치를 보임을 확인하였다.

• 한국음향학회지
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• 제37권2호
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• pp.92-98
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• 2018

본 논문은 모형 프로펠러를 대상으로 공동수조 시험, 수중 충격시험, 유한요소해석 및 전산유체해석에 기반하여 수행한 명음 발생 메커니즘 연구이다. 선미 유동을 모사하기 위해 반류망, 프로펠러 및 방향타를 설치하고 수중청음기와 가속도계로 프로펠러 명음 현상의 발생과 소멸을 계측하였다. 유한요소해석을 통해 프로펠러 날개의 고유진동수를 예측하고 접촉 및 비접촉식 충격시험으로 이를 검증하였다. RANS(Reynolds Averaged Navier-Stokes) 방정식 기반 전산유체해석을 통하여 프로펠러 날개 각 단면의 유속과 유효 받음각을 계산하였으며, DES(Detached Eddy Simulation) 기반 고해상도 해석을 통해 명음 발생 위치에서 2-D 날개 단면 뒷전의 와류흘림주파수(vortex shedding frequency) 계산을 수행하였다. 수치적으로 예측된 와류흘림주파수는 모형시험으로 계측한 명음 발생 주파수 및 날개 고유진동수와 일치함을 확인하였다.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2002년도 추계학술대회 및 정기총회
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• pp.93-97
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• 2002

본 논문에서는 자연언어를 이용하는 인간의 학습방법에 기초한 LIBL방법을 선박의 조타 시스템에 적용하여, 항해사의 조타명령과 같은 언어적 지시가 조타수를 경유하여 수행되는 과정을 대체하는 지능형 조타 제어 시스템을 제안하고자 한다. 구체적인 연구방법으로는 조타수의 적절한 조타조작모델을 퍼지추론규칙을 이용하여 구현하고, 적절한 의미소 및 평가규칙을 제시한 언어지시 기반 학습방법을 선박의 조타시스템에 적용하여, 항해사의 언어지시에 보다 효율적으로 응답하는 지능형 조타기 제어 시스템을 구현한다. 퍼지추론을 이용하여 조타수의 경험을 바탕으로 한 타 조작 모델을 구축하였고, 지능형 조타 시스템을 위한 타각, 방위도달시간, 정상상태의 의미소를 제안하여, 조타수 조작 모델 규칙을 수정하기 위한 평가규칙을 제시하였다. 또한, 구축된 선박조종 시뮬레이터에 제안된 시스템을 적용하여 그 유효성을 확인하였다.

• Journal of Ship and Ocean Technology
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• 제10권4호
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• pp.12-23
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• 2006

In this paper, a numerical study is carried out to investigate the turbulent flow around a twin-skeg container ship model with rudders including propeller effects. A commercial CFD code, FLUENT is used with body forces distributed on the propeller disk to simulate the ship stem and wake flows with the propeller in operation. A multi-block, matching, structured grid system has been generated for the container ship hull with twin-skegs in consideration of rudders and body-force propeller disks. The RANS equations for incompressible fluid flows are solved numerically by using a finite volume method. For the turbulence closure, a Reynolds stress model is used in conjunction with a wall function. Computations are carried out for the bare hull as well as the hull with appendages of a twin-skeg container ship model. For the bare hull, the computational results are compared with experimental data and show generally a good agreement. For the hull with appendages, the changes of the stem flow by the rudders and the propellers have been analyzed based on the computed result since there is no experimental data available for comparison. It is found the flow incoming to the rudders has an angle of attack due to the influence of the skegs and thereby the hull surface pressure and the limiting streamlines are changed slightly by the rudders. The axial velocity of the propeller disk is found to be accelerated overall by about 35% due to the propeller operation with the rudders. The area and the magnitude of low pressure on the hull surface enlarge with the flow acceleration caused by the propeller. The propellers are found to have an effect on up to the position where the skeg begins. The propeller slipstream is disturbed strongly by the rudders and the flow is accelerated further and the transverse velocity vectors are weakened due to the flow rectifying effect of the rudder.