• Title, Summary, Keyword: 횡동요

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Assessment of the Resistance Performance of Hull Appendages Attached to Fishing Vessels Using CFD (CFD에 의한 어선 선체 부가물의 저항성능 평가)

  • Park, Dong-Woo
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.24 no.2
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    • pp.267-274
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    • 2018
  • A variety of appendages are attached to coastal and offshore fishing boats to improve stability during navigation or fishing operations (stability performance and roll reduction). These appendages are generally classified into three types, which are shown in Fig. 1. The numerical calculations were conducted for the following eight cases: one case of a bare hull, three cases where a single appendage attached, three cases of a pair of appendages attached, and one case where all three appendages were attached. Table 1 presents the main dimensions of the bare hull and Table 2 describes the main dimensions of the three appendages. The fluid dynamic performance with regard to the three hull appendages was evaluated via CFD for the following cases: each of the appendages attached independently, a pair of appendages attached, and all three appendages attached simultaneously. The No. 1 appendage showed that pressure resistance was proportionally greater than friction resistances. Both Nos. 2 and 3 appendages showed comparable levels of pressure and friction resistances. The correlation between appendages was minimal in the case of pairs and Comparing the cases of the No. 2 appendage attached and all appendages attached, at 11 kn, the EHP showed an difference of 9 %.

A Fundamental Study on Lower Duct Flow of passive anti-rolling tanks System (수동형 감요수조의 하부덕트 유동에 관한 기초연구)

  • Lee, Cheol-Jae;Lim, Jeong-Sun;Jung, Han-Sic;Jung, Hyo-Min
    • Proceedings of KOSOMES biannual meeting
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    • pp.265-269
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    • 2006
  • Anti-Roll Tanks, also called Sloshing Tanks, is a rather common and sometimes an efficient method of limiting the roll angles. The important parameters, when considering using anti-roll tanks, are positioning, size, duct area, flow control device etc. Measurement by the PIV(Particle Image Velocimetry) was conducted to investigate the flow characteristics around control damper and inlet area of duct for three kind of inclined angle $(\alpha=0^*,\;10^*\;and\;20^*)$. Flow behaviors such as instantaneous and time-mean velocity vectors are investigated. Furthermore, to reveal boundaries between flowing and stagnant zones and to extract velocity profiles at any selected sections of the lower duct for passive anti-rolling tanks system.

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Modeling and Simulation of a Ship with Anti-Rolling Devices in Waves (자세제어장비를 장착한 선박의 파랑중 운동 모델링 및 시뮬레이션)

  • 윤현규;이경중;이창민
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • pp.285-290
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    • 2004
  • Wave exciting force and moment generate the motions of a ship in waves. Since ship motion exerts the negative influences on a crew's operability, the safety of cargos, passenger's comfort, etc, the anti-rolling devices may be required to reduce such motion. In this paper, the dynamics of the anti-rolling devices such as passive and active moving weight stabilizer and anti-rolling tank, and fin stabilizer are mathematically modeled. While the effect of the motion of the anti-rolling device on a ship was taken into consideration in roll mode only in the past, the 6 DOF coupled equations of motion between a ship and the anti-rolling devices are constituted. Finally the motion of a ship with anti-rolling devices in waves is simulated through the developed simulation program.

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Modeling and Simulation of a Ship with Anti-Rolling Devices in Waves (자세제어장비를 장착한 선박의 파랑중 운동 모델링 및 시뮬레이션)

  • Yoon, Hyeon-Kyu;Lee, Gyeong-Joong;Lee, Chang-Min
    • Journal of Navigation and Port Research
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    • v.28 no.5
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    • pp.347-352
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    • 2004
  • Wave exciting force and moment generate the motions of a ship in waves. Since ship motion exerts the negative influences on a crew's operability, the safety of cargos, passenger's comfort, etc, the anti-rolling devices may be required to reduce such motion In this paper, the dynamics of the anti-rolling devices such as passive and active moving weight stabilizer and anti-rolling tank, and fin stabilizer are mathematically modeled While the effect of the motion of the anti-rolling device on a ship was taken into consideration in roll mode only in the past, the 6 DOF coupled equations of motion between a ship and the anti-rolling devices are constituted Finally the motion of a ship with anti-rolling devices in waves is simulated through the developed simulation program.

Investigation on the Behavioral and Hydrodynamic Characteristics of Submerged Floating Tunnel based on Regular Wave Experiments (규칙파 실험에 의한 수중터널의 거동 및 동수역학적 특성 고찰)

  • Oh, Sang-Ho;Park, Woo Sun;Jang, Se-Chul;Kim, Dong Hyawn
    • Journal of The Korean Society of Civil Engineers
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    • v.33 no.5
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    • pp.1887-1895
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    • 2013
  • In this study, physical experiments were performed in a two-dimensional wave flume to investigate the hydraulic and structural performance of a SFT model. The experiments were made by generating regular waves of different heights and periods under various conditions of buoyancy to weight ratio (BWR) and water depth as well. Through the analysis of the experimental data, it was clarified that the sway and heave motions of the tunnel body linearly increased with wave height and period. In contrast, the roll motion was rather insignificant unless wave height and period were comparatively large as the design wave. Similarly proportional relationship with respect to wave height and period was obtained in case of the maximum tensile force acting on the tension legs and the wave loads on the tunnel body. Regarding the change of water depth or BWR conditions, generally decreasing trend was obtained according to increase of water depth but decrease of BWR for both of the magnitudes of structural behaviors or wave loadings on the SFT structure.

Dynamic Modeling and Simulation of a Towing Rope using Multiple Finite Element Method (다물체 요소이론을 이용한 예인줄 동역학의 모델링 및 시뮬레이션)

  • Yoon, Hyeon-Kyu;Lee, Hong-Seok;Park, Jong-Kyu;Kim, Yeon-Gyu
    • Journal of Navigation and Port Research
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    • v.36 no.5
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    • pp.339-347
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    • 2012
  • After towing rope connecting a barge to a tug was subdivided into multiple finite elements, then those dynamic models was established using Newton's second law and considering the external force and moment such as tension, drag, Coriolis force, gravity, buoyancy, and impact due to free surface acting on each element. While the previous research on the model of towing rope considered only translation, five-degree-of-freedom equations of motion except roll based on the body-fixed frame were established in this paper. All elements are connected by a spring and a damper, and the stiffness of the spring was set as the equivalent value of the real rope. In order to confirm the established multiple finite element model, various scenarios such as freely falling of towing rope in the air and above the free surface, accelerating of a tug which tows a barge connected by towing rope, and sinusoidal moving of a tug were set up and simulated. As the results, the trajectories of the tug, the barge, and the towing rope showed good tendencies to the ones of real expected situations.