• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.696-703
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• 2005

Recently, the collision problems between a bridge and a navigating ship are frequently issued at the stage of structure design. Even the many study results about vessel to vessel collision are presented, but the collision studies between vessel and bridge structure have been hardly presented. In this study, nonlinear dynamic analysis of vessel and fender system carry out using ABAQUS/Explicit commercial program with consideration of some parameters, such as bow structure we composed to shell element also ship's hull is modeling to beam element. Also, buoyancy effect is considered as spring element. The two types of fender systems was comparable with both collision analysis about steel materials fender system and rubber fender system On the purpose of study is analyzed the plasticity dissipated energy of vessel and fender system. We blow characteristic that kinetic energy is disappeared by plastic large deformation in case of collision. Also, We considered dissipated kinetic energy considering friction effect.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.3
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• pp.469-475
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• 2010

The operation scenarios, types of ice, draft and propulsion system are important design point on the beginning stage of the ice breaking vessel. The concept of hull form in ice breaking vessel has to compromise the performance according to the operation route especially if ship is operating in ice and ice free water. The several hull forms were proposed to optimize the capability of the vessel in this paper. The effect of hull form according to type of ice is also discussing and explaining the ice resistance in each ice type as like pack ice, brash ice, level ice, rubble ice and ice ridge. The draft effect was examined and propulsion system for example FPP(Fixed pitch propeller), CPP(Controllable pitch propeller) and POD system was compared focusing on the propulsion efficiency.

• Journal of Navigation and Port Research
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• v.35 no.7
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• pp.557-562
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• 2011

Shipwaves can have harmful effects on people who are using riverside and cause bank erosion, bank structures destruction in restricted waterways. The wave field near a vessel is consisted of a combination of a primary and secondary wave system in a shallow or restricted waterway. The water level depression(squat) and return current beside the hull are called the primary wave system. The secondary wave system, that is the wave height originates from a local disturbance point such as the bow of the ship. This study aims at investigating the characteristics of the wave field around a vessel in a restricted water in relation to navigation experimentally and theoretically. The return current and squat with a correction factor can be newly evaluated and the almost same high-sized wave heights take place on the whole waterway in a restricted water without regard to the distance from the sailing line.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.9
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• pp.823-828
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• 2013

To reduce the cost per watt of photovoltaic power, it is important to reduce the cell thickness of crystalline silicon solar cells. As the thickness of the silicon layer is reduced, two distinctive thermal expansion rates between the silicon and the aluminum layer induce bowing in a solar cell. With a thinner silicon layer, the bowing distance grows exponentially. Excessive bowing could damage the silicon wafer. In this study, we tried to measure an irregularly curved silicon solar cell more accurately using a 3D image scanner. For the detailed analysis of the three-dimensional bowing shape, a least square fit was applied to the point data from the scanned image. It has been found that the bowing distance and shape distortion increase with a decrease in the thickness of the silicon layer. An Ag strip on top of the silicon layer can reduce the bowing distance.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.5
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• pp.367-375
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• 2012

In this study, hull form of main vessel of Korean large purse seiner fishing industry is developed for the improvement of resistance performance as well as for the satisfaction to the Standard of Fishing Convention, ILO. Through the modification of reference hull form parameters and local characteristics, the hull form development is carried out. The optimum hull form parameters are searched by Sequential Quadratic Programing(SQP) method with the power estimation method of Holtrop & Mannen. To minimize the wave resistance, bulbous bow parameters are determined by the bulbous bow design method of Alvarino. The plasmatic curve is redesigned from that of the reference hull by using Lackenby method. The resistance performances of the reference and designed hull forms are estimated by using numerical simulation method. Also, the judgment of seakeeping ability and the estimation of intact stability for the designed hull form is carried out. As a result, the optimum hull form is proposed. To verify the improvement of resistance performance, model tests are carried out in towing tank. The results show that the resistance of the designed hull form is about 14% smaller than that of the reference hull from at design speed. A new hull form proposed in this study can contribute to the development of the main vessel hull form of Korean large purse seiner fishing system.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.1
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• pp.66-74
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• 2024

This study addresses the escalating issue of worldwide hydrogen gas accidents, which has seen a significant increase in occurrences. To comprehensively evaluate the risks associated with hydrogen, a two approach was employed in this study. Firstly, a qualitative risk assessment was conducted using the bow-tie method. Secondly, a quantitative consequence analysis was carried out utilizing the areal locations of hazardous atmospheres (ALOHA) model. The study applied this method to two incidents, the hydrogen explosion accident occurred at the Muskingum River power plant in Ohio, USA, 2007 and the hydrogen storage tank explosion accident occurred at the K Technopark water electrolysis system in Korea, 2019. The results of the risk assessments revealed critical issues such as deterioration of gas pipe, human errors in incident response and the omission of important gas cleaning facility. By analyzing the cause of accidents and assessing risks quantitatively, the effective accident response plans are proposed and the effectiveness is evaluated by comparing the effective distance obtained by ALOHA simulation. Notably, the implementation of these measures led to a significant 54.5% reduction in the risk degree of potential explosions compared to the existing risk levels.

• Journal of the Korean Society for Marine Environment & Energy
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• v.2 no.2
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• pp.86-94
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• 1999

This paper describes a development of Collision/grounding Strength Assessment System (COSAS) using simplified method. This method is formulated in closed-form equation by taking into account crushing caused by bulbous bow collision and cutting caused by forward speed grounding. To verify the accuracy of the developed system, some examples for test models of double side/bottom structure in collision/grounding situation are considered. This system might be useful for analysis of structural damage of oil tankers in collision/grounding.

• Proceedings of KOSOMES biannual meeting
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• 2003.11a
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• pp.127-133
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• 2003

In this study, the impact analysis for the steel fender system that designed for protection of collision between vessel and bridge was performed The size of objective collision vessel assumed as 3000 dead weight tonnage(DWT). The impact forces and the impact energies were estimated by formulas of several design codes, and the steel fender system was designed based on the estimated forces and energy. The bow of objective vessel was modeled as rigid body, and bridge substructure was modeled as fixed support. Since, the impact analysis have the dynamic nonlinear features, such as, material nonlinear, large deformation and contact, explicit structural analysis program was used The analysis results presented that the impact forces formulas in codes have the sufficient conservativeness.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.71-78
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• 2003

In this study, the impact analysis for the steel fender system that designed for protection of collision between vessel and bridge was peformed. The size of objective collision vessel assumed as 3000 dead weight tonnage(DWT). The impact forces and the impact energies were estimated by formulas of several design codes, and the steel fender system was designed based on the estimated forces and energy. The bow of objective vessel was modeled as rigid body, and bridge substructure was modeled as fixed support. Since, the impact analysis have the dynamic nonlinear features, such as, material nonlinear, large deformation and contact, explicit structural analysis program was used. The analysis results presented that the impact forces formulas in codes have the sufficient conservativeness.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.124-128
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• 2002

This Paper propose a novel sensorless drive system for the trapezoidal brushless DC motor in Bow speed region. The inverter DC input voltage is controlled by step-down converter for low speed operation. A indirect rotor position sensing technique based on a detailed analysis of the terminal voltage characterisrics is proposed in this paper. A sensorless drive system is implemented using a TMS320F240 for the main process and IPM(Intelligent Power Module) for the inverter.