• Journal of Ship and Ocean Technology
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• v.6 no.1
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• pp.1-15
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• 2002

A new concept for launching free-fall lifeboats, proposed by Yokohama National University is described in this paper. It has been pointed out that, using the conventional single-skid free-fall system, the potential for dangerous lifeboat motions (in which the lifeboat moves backward or jerks on the surface after entering the water) increases with the fall height of the lifeboat. One of the principal causes of this undesirable motion is vertical rotation of the lifeboat during its restricted fall at the edge of the launching skid. Thus a new "double-skid"launching concept is proposed to effectively eliminate the rotation of the lifeboat at the skid end and to enable the lifeboat to move smoothly after entering the water. In order to evaluate the performance of the proposed method, a series of model experiments and numerical simulations is carried out in which two lifeboat models with overall lengths of 1 meter and 6 meters are used. The effects of design parameters such as skid angle and skid height are investigated, and an example of the implementation of this new system at the stern of a large merchant ship is illustrated.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.04a
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• pp.241-247
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• 2001

A Fire Safety Evaluation Module(FSEM), which quantitatively evaluates the risk of evacuees when fire occurs in buildings or ships, is presented in this paper. The developed FSEM can be applied to multi-room structure. Basic input data for the FSEM are prepared by fire model and evacuation model. CFAST which is one of the existing fire models is used as fire model and MonteDEM evacuation model was developed for evacuation model, respectively. MonteDEM evacuation model makes use of distinct element method and Monte-Carlo simulation, and it can also take into consideration ground inclination by ship motions in order to simulate the real situation of evacuation. Some typical situations are modelled for illustrative examples and quantitative assessment of evacuee's risk under fire accident is carried out.

• Special Issue of the Society of Naval Architects of Korea
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• 2011.09a
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• pp.70-74
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• 2011

This paper describes the quay mooring analysis to verify the safety of a moored drillship in typhoon conditions. Mooring system consists of mooring equipments(deck bollards, shore bitts, mooring lines, fenders) to resist the extreme environmental condition. Wind force acting on the drillship is obtained from the wind tunnel test results. The strength of quay mooring system has been checked. The static mooring analysis shows that the designed mooring system satisfies the mooring design criteria. Vertical displacements of the drillship have been calculated considering the dynamic wave motions and static heelings due to the wind force acting on the ship. With the vertical displacements and the hull draft of drillship, the required water depth for quay mooring has been derived.

• Proceedings of KOSOMES biannual meeting
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• 2001.05a
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• pp.53-77
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• 2001

선박의 항행안전의 문제가 중요시됨에 따라 선박조종시뮬레이터에 의한 안전성 검토의 필요성이 크게 인식되고 있다. 또한 조종성능을 향상시킬 목적으로 다양한 선종이 출현하고 있고, 이에 따라 선박조종시뮬레이터의 개발에 있어서 선박의 데이터베이스는 필수적이라고 할 수 있다. 따라서 선종에 따른 수학모델을 각각 선박조종시뮬레이터에 적용시킴으로써 다양성이라는 가상현실의 잇점을 한층 부각시킬 수 있다. 본 연구에서는 우수한 추진성능을 목적으로 한 2축2타선박을 대상으로 조종운동 수학모델을 정식화하였다. 구체적으로 항만내에서의 저속시 조종운동을 구현할 수 있는 수학모델에 대해서 검토하였으며, 선체·프로펠러·타의 상호간섭에 대해서도 고려하였다. 또한, 수치시뮬레이션을 수행함으로써 2축2타선박의 기본적인 조종성능을 확인할 수 있었다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.2 no.1
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• pp.143-143
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• 1996

Recent Class requirements and IMO recommendations concerning Hull Strength Monitoring (HSM) have prompted an increasing number of shipowner to adopt monitoring systems on bulk carriers and tanker. Such systems are designed to give warning when stress levels and the frequency and magnitude of ship motions approach levels which require corrective action. When fitted these systems provide enhanced operational safety and efficiency. This paper describes a development beyond the standard BMT HSM system through the integration of stress, motion and radar-based sea state monitoring with powerful, on-board, artificial intelligence (AI) tools. The latter utilises conceptual clustering techniques as an aid to pattern recognition in stress, fatigue. motion and sea state data clusters. This, in turn, provides additional operational guidance for ship's staff. Feedback from applications of the standard BMT HSM and extended HSM systems on board the British Steel Bulk Shipping fleet is described.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.3
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• pp.297-302
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• 2015

To prevent cargo accidents by repeated loads, a continuous monitoring for securing rope or additional safety measures are needed, but most of prevention measures have been conducted only by operator's own experience not a quantitative assessment. Hence, the Load-Displacement curve and approximation formula of securing rope were drawn in this research for a quantitative assessment and simplified measurement on a tension of securing rope using a tensiometer. Moreover, a com parison was conducted between m easuring tension and calculated tension on securing rope with portable tensiometer, 'Load-Displacement' approximation formula. The calculated tension of securing rope is obtained 153.3kfg using the formula and that result has not much difference with initial tension 150.0kgf. Lastly, an analysis of the characteristics of various ropes was suggested to enhance the reliability about quantitative assessment of securing rope's tension through further research.

• Journal of Ship and Ocean Technology
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• v.7 no.2
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• pp.1-19
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• 2003

This paper introduces a unified theory for the radiation problem of adjacent multiple floating bodies. The particular case of interest is the multiple slender bodies that their centerlines are parallel. The infinite-and finite-depth unified theories for the single-body problem are extended to solve each sub-problem of multiple bodies. The present method is valid for deep water and moderate water depth, and applicable for individually floating bodies as well as multimaran-type vehicles. For the validation of the present method, the heave and pitch hydrodynamic coefficients for two adjacent ships are compared with the results of a three-dimensional method, and an excellent agreement is shown. The application includes the hydrodynamic coefficients and motion RAOs of four trimarans which have different longitudinal and transverse arrangements for sidehulls.

• Journal of the Korean Institute of Navigation
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• v.25 no.3
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• pp.247-256
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• 2001

This study aims to develop the information service system of integrated seakeeping performance for seagoing vessels. It has been successful in developing the intended system which has made possible to provide the following functions and capabilities. o immediate computation of the dynamic motions of a ship against the present and future weather conditions; o evaluation of the integrated seakeeping performance of a ship on a real time basis and providing the navigators with the seakeeping informations on the spot enabling them to take the most appropriate countermeasures; and o supporting the navigators in the selection of a safe sailing route by providing the integrate seakeeping performance.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.2
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• pp.211-218
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• 2021

This paper addressed the problems of controlling the coupled pitch-roll motions in a marine vessel exposed to the regular waves in the longitudinal and transversal directions. Stabilization of the pitch and roll motions can be regarded as the essential task to ensure the safety of a ship's navigation. One of the important features in the pitch-roll motions is the resonance phenomena, which result in unexpected large responses in terms of pitch and roll modes in some specific conditions. Besides, owing to its inherent characteristics of coupled combination and nonlinearity of restoring terms, the vessel shows various dynamical behaviors according to the system parameters, especially in the pitch responses. Above all, it can be seen that suppression of pitch rate remains the most significant challenge to overcome for ship maneuvering safety studies. To secure the stable upright condition, a quasi-sliding mode control scheme is employed to reduce the undesirable pitch and roll responses as well as chattering elimination. The Lyapunov theory is adopted to guarantee the closed stability of the pitch-roll system. Numerical simulations demonstrate the effectiveness of the control scheme. Finally, the control goals of state convergences and chattering reduction are effectively realized through the proposed control synthesis.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.209-212
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• 1987

This paper presents a control scheme to stabilize a two-axes microwave antenna system which is located on a ship and is subject to roll, pitch and yaw(RPY) motions. The scheme first computes the compensated angular positions of the antenna for RPY disturbances through coordinate transformations, and then use a servo con roller of PID type for each axis to track the compensated position command with a good transient behavior.