• 대한조선학회논문집
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• 제42권4호
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• pp.341-349
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• 2005

With increasing demands of high speed transportation, recently a lot of high speed marine vehicles, such as SWATH, semi-planing craft, planing craft, hydrofoil craft, SES and so on, have been paid attention especially in high speed region over the Froude number 0.5. The resistance characteristics of the vehicles should be experimentally evaluated in the towing tank. At the Seoul National University, a light-weight cantilever type towing carriage was devised and installed in the towing tank. Wireless measurement devices were also provided for appropriate data acquisition during high-speed towing tests. With the new carriage system, a series of model tests were performed to investigate the hydrodynamic characteristics of a stepped planning hull in the towing tank and the resistance performances of the hull are introduced in this report.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.12-23
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• 2021

In the conventional experiment to assess the towing operations, the towing stability of the towed vessel has been evaluated under the condition without lateral motion of the tug-boat. However, the tug-boats may have a lateral force to change the direction of the towed vessel. In this study, experiments have been conducted considering unsteady conditions in the towing system. First, a towing test system in a Circular Water Channel (CWC) using the conventional experimental method is built. Second, the towing characteristics of the towed vessel are investigated using the conventional method, and they are compared with other research results and stability discriminant criteria. Third, the lateral motion of the tug-boat was modeled as a sinusoidal motion using a forced oscillation device changing frequency and amplitude. Finally, the discussion is given in terms of both towing- and course-stability of the towed vessel according to the lateral motion of the tug-boat.

• 한국해양공학회지
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• 제29권4호
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• pp.283-290
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• 2015

This paper presents the results of a numerical study on the towing characteristics of a barge under various wind conditions. First, stability criteria, including the wind force, were derived based on the linear motion equations of a towed vessel. The effect of the wind force on the towing stability was investigated using stability criteria. Next, towing simulations were carried out using a nonlinear time-domain simulation method. In this case, the towline was modeled as a simple spring-damper, and the wind force was computed using the wind coefficient from CFD calculations. Simulations were conducted for a barge under a constant towing speed and constant wind speed conditions. The effect of the wind direction on the slewing motion was also observed. In addition, a series of numerical simulations using variable wind speeds were performed for the present barge with and without a skeg.

• 수산해양기술연구
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• 제41권2호
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• pp.122-128
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• 2005

The experiments were conducted to fine out the handling characteristics of the FMT(Frame Mideater Trawl) in the southern waters of Korea using a trawler "DONGBAEK" belongs to Yosu National University. The realtionship between the net depth D(m) and the warp length L(m) at the towing speeds of 2.5k't and 3.5k't werw as follows ; D(m) = 0.30L - 1.3(2.5k't), D(m) = 0.16L - 1.5(3.5k't). Therefore, the net depth was 3.0m deeper when the warp length was 10m longer at the towing speed of 2.5k't and was 1.6m deeper for 10m longer at the speed of 3.5k't, respectively. The sinking speed of FMT was 6.5m/min when the warp releasing speed was 24m/min at the towing speed of 2.5k't and was 3.8m/min for 25m/min at the towing speed of 3.5k't, respectively. The rising speed of FMT was 6.9m/min when the warp rewinding speed was 28m/min at the towing speed of 2.5k't and was 5.3m/min for 25m/min at the towing speed of 3.5k't, respectively. The mean elapsed time getting to the stable towing condition was 104sec at the towing speed of 2.5k't and was 105sec at the towing speed of 3.5k't, respectively, and there was no time difference for the towing speed variation. During the towing, the net depth was comparatively stable on the condition of no change for the warp length and the towing speed.

• 한국해양공학회지
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• 제36권1호
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• pp.50-60
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• 2022

The deep ocean engineering basin (DOEB) of the Korea Research Institute of Ship and Ocean Engineering (KRISO) is equipped with an extreme-environment reproduction facility that can analyze the motion characteristics of offshore structures and ships. In recent years, there have been requirements for a wide range of six-degree-of-freedom (6-DOF) motion measurements for performing maneuvering tests and free-running tests of target objects (offshore structures or ships). This study introduces the process of developing a wide-area motion measurement technology by incorporating the auto-tracking technology of the towing carriage system to overcome the existing 6-DOF motion measurement limitation. To realize a wide range of motion measurements, the automatic tracking control system of the towing carriage in the DOEB was designed as a speed control method. To verify the control performance, the characteristics of the towing carriage according to the variation in control gain were analyzed. Finally, a wide range of motions was tested using a model test object (a remotely operated vehicle (ROV)), and the wide-area motion measurement technology was implemented using an automatic tracking control system for a towing carriage.

• Journal of Ship and Ocean Technology
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• 제9권2호
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• pp.1-10
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• 2005

A light-weight cantilever type towing carriage was devised and installed in the towing tank at Seoul National University. Wireless measurement devices were also provided for appropriate data acquisition during high-speed towing tests. With the new carriage system, a series of model tests were performed to investigate the hydrodynamic characteristics of the racing boat in the towing tank and the resistance test results had sufficient accuracy so that they could be used in the development of a high speed planning hull.

• Journal of Advanced Marine Engineering and Technology
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• 제34권5호
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• pp.718-724
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• 2010

공동수조와 예인수조에서의 프로펠러 단독특성 차이를 보정할 수 있는 위벽효과 연구를 수행하였다. 우선 공동수조의 실험에서 프로펠러의 상류가 아닌 작동 평면 위치에서 계측된 유속을 프로펠러 전진속도로 정의할 경우, 위벽효과의 수정 량 및 단독특성차이가 현저히 줄어드는 것을 확인하였다. 다음으로 양력판 이론에 의한 단독특성 계산을 통해, 프로펠러 평면에서의 위벽효과를 구하고 앞의 결과에 추가적인 보정을 수행하였다. 그 결과, 예인수조에서의 단독특성과 더욱 더 좋은 일치를 보여 주는 것을 확인하였다.

• 해양환경안전학회지
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• 제15권1호
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• pp.57-62
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• 2009

예부선 운항 시 부두의 접안, 이안 및 좁은 수로를 항행할 경우 접할 수 있는 안벽 근처의 항행과, 두 선박이 접근하여 평행 항로상을 반대 방향으로 항과할 경우의 유체력 상호작용을 살펴보기 위하여, 예선의 부선 예항 시뮬레이션을 실시한 후 부선의 선수방향, 예선의 회두 모멘트와 횡방향의 힘과 같은 특성을 조사 및 분석하여 그에 따른 안전한 예부선의 조선 방안을 제시하였다. 그 결과 부선의 과도한 회두운동을 감소시키기 위해서는 예선의 속도가 너무 느리지 않도록 미속상태의 속도를 유지하고, 예인삭의 길이를 가능한 한 부선의 길이만큼 줄여 항행하는 것이 안전예항 업무에 도움이 될 것으로 판단된다.

• 대한조선학회논문집
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• 제36권3호
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• pp.22-28
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• 1999

3차원 Fiber Optics LDV를 사용하여 예인수조에서 180,000 톤급 살물 모형선의 프로펠러면에서의 유속을 측정하였다. 평균속도를 성공적으로 구하였으며 전단 응력, skewnesses 및 flatnesses 등의 난류특성에 대해서도 조사하였다. 그러나 이러한 난류유동 특성은 예인수조에서의 실험 특성상 약간의 오차를 포함하고 있다.

• 한국해양공학회지
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• 제28권2호
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• pp.102-110
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• 2014

This paper presents the results of an experimental and numerical study on the towing characteristics of a barge. A series of model tests were carried out at the Ocean Engineering Basin of KRISO. A model with a 1:50 scale ratio was constructed out of wood. First, force coefficient tests were performed in order to obtain the surge, sway, and yaw force coefficients of the barge. The focus was the effect of skeg on the force coefficients. The stability parameter was calculated from the force coefficients. Next, towing tests in calm sea were carried out with different towline lengths and towing speeds. The trajectories of the barge and the towline tensions were measured during the tests. The measured trajectories were compared with numerical simulation results using a cross-flow model. The towing stability of the barge in a calm sea is discussed in detail.