• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2006년도 Asia Navigation Conference
• /
• pp.71-78
• /
• 2006

The image of an object obtained by the radar is not corresponding to its true shape, because the image of an object observed by the radar is receiving an influence such as multiple-reflections and expanded in bearing because of the beam width of a radar. In addition, a radio wave does not hit the entire surface of an object. Therefore, the image of the front side of a ship facing a radar antenna corresponds to its true shape. In this paper, a method to estimate a ship's shape by means of the integration of the front parts of images obtained from radars is proposed. In addition, a matter, which is observation error of each radar, in using multi-radars, and the process included in the proposed method for solving the matter, are described. As a result of the experiment, the accuracy of about 3 degrees in ship's heading and about 14 meters in length and about 9 meters in beam was obtained.

• Journal of Advanced Marine Engineering and Technology
• /
• 제38권10호
• /
• pp.1217-1224
• /
• 2014

This paper provides a practical scaling method to solve an old problem for scaling and developing the speed and resistance of a model to full-scale submarine in fully submerged underwater test. In every experimental test in towing tank, water tunnel and wind tunnel, in the first step, the speed of a model should be scaled to the full-scale vessel (ship or submarine). In the second step, the obtained resistance of the model should be developed. For submarine, there are two modes of movement: surface and submerged mode. There is no matter in surface mode because, according to Froude's law, the ratio of speed of the model to the full-scale vessel is proportional to the square root of lengths (length of the model on the length of the vessel). This leads to a reasonable speed and is not so much for the model that is applicable in the laboratory. The main problem is in submerged mode (fully submerged) that there isn't surface wave effect and therefore, Froude's law couldn't be used. Reynold's similarity is actually impossible to implement because it leads to very high speeds of the model that is impossible in a laboratory and inside the water. According to Reynold's similarity, the ratio of speed of the model to the full-scale vessel is proportional to the ratio of the full-scale length to the model length that leads to a too high speed. This paper proves that there is no need for exact Reynold's similarity because after a special Reynolds, resistance coefficient remains constant. Therefore, there is not compulsion for high speeds of the model. For proving this finding, three groups of results are presented: two cases are based on CFD method, and one case is based on the model test in towing tank. All these three results are presented for three different shapes that can show; this finding is independent of the shapes and geometries. For CFD method, Flow Vision software has been used.

• 해양환경안전학회:학술대회논문집
• /
• 해양환경안전학회 2017년도 공동학술발표회
• /
• pp.143-143
• /
• 2017

• 한국항해학회지
• /
• 제11권1호
• /
• pp.67-91
• /
• 1987

In this paper, a synthetic method for evaluating the seakeeping performance of a ship in waves is studied. For the prediction and evaluation of irregular phenomena to be correlated each other, the multi-dimensional Rayleigh's joint probability density function and the cumulative distribution function are approximated. According to this approximated function, it is able to calculate easily the occurrence probability of the factors on seakeeping performance. We proposed an evaluation method and an index to be defined by the seakeeping performance reliability, that is considered as the dangerousness and the relative dangerousness of the factors on seakeeping performance in waves. The use of this method aid index will be effective to install the sensors which are necessary to evaluate the states of ships at sea. Some example of the calculations by this method for 175m length single screw container ship equipped with diesel engine are also presented.

• 해양환경안전학회:학술대회논문집
• /
• 해양환경안전학회 2003년도 춘계학술발표회
• /
• pp.159-165
• /
• 2003

To Recently, the buckling is easy to happen a thin plate and High Tensile Steel is used at the structure so that it is wide. Especially, the buckling is becoming important design criteria in the ship structure to use especially the High Tensile Steel. Consequently, it is important that we grasp the conduct after the buckling behaviour accurately at the stability of the body of ship structure. In this study, examined closely about conduct and secondary buckling after initial buckling of thin plate structure which receive compressive load according to various kinds aspect ratio under simply supported condition that make by buckling formula in each payment in advance nile to place which is representative construction of hull. Analysis method is F.E.M by ANSYS and complicated nonlinear behaviour to analyze such as secondary buckling.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2003년도 봄 학술발표회 논문집
• /
• pp.496-503
• /
• 2003

Recently, the buckling is easy to happen a thin plate and High Tensile Steel is used at the structure so that it is wide. Especially, the buckling is becoming important design criteria in the ship structure to use especially the High Tensile Steel. Consequently, it is important that we grasp the conduct after the buckling behaviour accurately at the stability of the body of ship structure. In this study, examined closely about conduct and secondary buckling after initial buckling of thin plate structure which receive compressive load according to various kinds aspect ratio under simply supported condition that make by buckling formula in each payment in advance rule to place which is representative construction of hull. Analysis method is F.E.M by ANSYS and complicated nonlinear behaviour to analyze such as secondary buckling.

• 해양환경안전학회지
• /
• 제28권6호
• /
• pp.1100-1109
• /
• 2022

본 연구에서는 전장이 400m인 24,000TEU급 컨테이너선박을 대상으로 선박 내 빌지펌핑의 성능에 대한 케이스 스터디를 수행하였다. 본 연구의 대상인 24,000TEU급 컨테이너선박의 빌지시스템의 경우 선급의 규칙에 맞게 설계되었지만, 선박 내 설치되어 있는 빌지펌프의 정격유량 및 최대유량 조건에서도 SOLAS Reg.II-1/35-1의 2 m/s 요건을 만족시키지 못하였다. 특히 1번 ~ 4번 화물창에 대해, 해수로 가득차 있다고 가정한 상태에서 해수를 모두 배출하는 동안에 빌지 주관에서의 평균유속을 계산할 결과, 2번 화물창, 3번 화물창 및 4번 화물창은 평균유속이 2 m/s 미만으로 기준에 적합하지 않은 것으로 나타났다. 본 연구에서는 이를 해결하기 위해 2번, 3번 및 4번 화물창의 150A 빌지 지관을 200A 배관으로 교체하여 계산을 수행하였으며, 그 결과 화물창 내의 해수를 모두 배출하는 동안의 빌지 주관에서의 해수평균유속이 각각 2.479m/s, 2.476,m/s 및 2.459m/s 로 기준을 만족시키는 것을 알 수 있었다.

• 대한조선학회논문집
• /
• 제48권1호
• /
• pp.8-14
• /
• 2011

RIB(Rigid Inflatable Boat) is widely used for coastal transportation in the commercial use and for ISR(Intelligence, Surveillance, Reconnaissance) in the military use. Since RIB is around 10 meters in length and over 30 knots in speed, its motion characteristics in waves is quite different from a large scale ship. When it turns, large roll occurs and heeling direction is opposite to the large ship's case. Currently, many countries are developing USV(Unmanned Surface Vehicle) of which type is RIB. In order to develop high performance autopilot and way point controller, it is very important to identify RIB's motion characteristics. In this paper, sea trial test results of a 7-meter RIB such as speed, turning, zig-zag, and way point control tests were represented and its resistance and propulsion model was identified by using sea trial data and Savitsky's formula. In addition, the state space model which will be used in the identification of the four-degree-of-freedom dynamics in the next step was formulated and the identification procedure was proposed.

• 수산해양기술연구
• /
• 제22권1호
• /
• pp.24-28
• /
• 1986

The maneuverabilities of the M. S. PUSAN 402 are studied, based on maneuvering indices and the data obtained from her Z test. The results obtained are summarized as follows: 1. The maneuvering indices K' and T' of the M. S. PUSAN 402 are 1. 490, 1.030 at 10$^{\circ}$ Z test and 2.644, 1.153 at 20$^{\circ}$ Z test and 3.382. 1. 027 at 30$^{\circ}$ Z test respectively. The above calculated values K', T' showed that her maneuverabilities are more increased when the rudder is used to large angle than to smaIl angle. 2. As her maneuvering indices K' and T' at 10$^{\circ}$ Z test are higher than the standard maneuvering indices of fishing boats, her turning ability was found to be higher but her obeying ability lower. 3. When the M. S. PUSAN 402 took a turn at her 10$^{\circ}$ test, running distance was about 8.4 times her own length and didn't exceed the standard maneuvering distance, 5 to 11 times ship's own length, therefore she was considered to have good maneuverabilities syntheticaIly.

• 수산해양기술연구
• /
• 제18권2호
• /
• pp.77-80
• /
• 1982

총톤수 240 톤급 가다랑어 채낚기 어선의 조종성능을 연구하기 위하여, 실선에 의한 Z실험을 행한 결과를 요약하면 다음과 같다. 1. $10^{\circ}$Z실험에서의 선회성지수 K'는 0.611, 추종성지수 T'는 1.094, 20$^{\circ}$Z시험에서의 K'는 0.622, T'는, 1.695, 30$^{\circ}$Z시험에서 K'는 1.367로서 추종성은 $10^{\circ}$타각, 선회성은 20$^{\circ}$타각을 사용할 때 가장 좋으며, 전체적으로는 $10^{\circ}$의 소타각을 사용할 때의 조종성능이 20$^{\circ}$, 30$^{\circ}$의 대타각을 사용할 때 보다 더 양호하다는 것을 알 수 있다. 2. 조종성지수 K' 및 T'가 다른 종류의 선박들의 그것과 비교하여 작으므로, 추종성은 양호하나 선회성은 나쁘다는 것을 알 수 있다. 3. $10^{\circ}$Z시험에서의 1조작간 항주거리인 5~11배 이내이므로 종합적으로는 조종성능이 양호하다고 볼 수 있다.