• Tribology and Lubricants
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• v.14 no.3
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• pp.87-93
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• 1998

Crank pin bearing in two-stroke marine diesel engine is operated under quite severe conditions since the elements are big and heavy and the sliding speed is very slow. Therefore it is very difficult to form oil film. In this paper, two types of bearings with different groove shape are compared. One has circumferential oil groove at lower position and the other has lengthwise oil groove at upper position. Bearing clearance, oil inlet pressure and length to diameter ratio are selected as design parameters. Locus of journal center and minimum oil film thickness are investigated to compare two cases.

• Tribology and Lubricants
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• v.7 no.2
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• pp.75-84
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• 1991

The static and dynamic performances of a floating ring journal bearing with central circumferential grooves at the inner and outer films are obtained numerically with isothermal lubrication theory. Elrod algorithm implementing Jakobsson-Floberg-Olsson cavitation boundary condition is adopted to predict cavitation regions in the inner and outer films more accurately than conventional analyses using half Sommerfeld or Reynolds conditions. The pressure drop in the circumferential groove of the inner film due to the rotation of the journal and ring is taken into account. It is shown that the lubricant supply pressure has significant influence on the load capacity and dynamic coefficients of the bearing. When the supply pressure is low and the journal speed is high, the pressure drop results in severe starvation of lubricant in the inner film and varies the overall performance of the bearing remarkably.

• Tribology and Lubricants
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• v.6 no.2
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• pp.76-87
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• 1990

It is known that the effects of oil supply conditions on the characteristics of plain journal bearings are significant and especially the dynamic characteristics are affected by cavity region. For various shapes (axial groove, spiral groove, X-shape groove) and positions of oil grooves, the pressure distribution and the static performance of plain journal bearings are obtained with numerical methods. Elrods algorithm which implements JFO oil rupture/reformation boundary condition is used in order to take into account the effect of cavity region. It is shown that in the cases of axial groove or X-shape groove the load capacity and the attitude angle are affected by the groove position but the effect of spiral groove position is less significant.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.10a
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• pp.58-60
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• 2013

부산항 입항 및 출항 대기, 통과 선박의 중간 기항지로 이용되는 부산 남외항 대기 정박지는 N-1~N-5으로 구성되며 현재, 최대 90척이 동시에 정박 가능한 집단 정박지 지정방식으로 지정되어 있다. 부산 남외항 대기 정박지는 입 출항 선박 및 통과 선박, 급유선 등의 교통에 따른 충돌, 접촉 등의 해양 사고와 갑작스러운 돌풍 등 기상악화에 따른 충돌, 접촉 및 좌초 등의 해양 사고가 발생하고 있다. 부산 남외항 대기 정박지의 자연 환경, 이용현황, 기상, 입 출항 선박 및 통과 선박의 교통 흐름을 종합적으로 살펴보고 부산 남외항 대기 정박지에서 발생하는 해양사고를 분석하였다. 따라서 부산 남외항 대기 정박지의 운영상의 문제점을 찾고, 해상교통조사 설문조사 이론적 근거를 기초로 안전도 평가 시스템을 사용하여, 향후 개선방향을 제시하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.578-583
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• 1997

Abstract-Crosshead bearing in two-stroke marine diesel engine is operated under quite severe condition since the load on the bearing is sybject to the loading in a unidirectional and the sliding speed is very slow and oscillatory. So it is very difficult to form oil film and maintain the load. In this paper, two types of bearing are compared. One has large sized oil pocket and the seleted as multi-small oil grooves. Bearing clearance, oil inlet oressure and bearing types are selected as analysis parameters. Loci of journal center are presented to compare several cases. It is found that bearing clearance and shape affect to minimum film thickness.

• Special Issue of the Society of Naval Architects of Korea
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• 2013.12a
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• pp.94-96
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• 2013

Since LNG has explosive properties and difficulty to handle, it was avoided using LNG as fuel. However, recently LNG has been considered as alternative fuel of HFO. Several LNG fuel supply system has developed. Furthermore, STX ONS is developing LNG fuel bunkering system and bunkering shuttle. Bunkering shuttle carries out refueling LNG fuel while LNG fuel ship is on cargo work. In case of emergency, bunkering shuttle breakaway from the ship but a little amount of LNG falls down on deck. It can disperse to cargo work area also can explode. In this case LNG dispersed on deck was not considerable.

• Journal of Power System Engineering
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• v.9 no.4
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• pp.24-30
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• 2005

For a reciprocating compressor of household refrigerators, a direct analogy between the pipe flow network and the electric circuit network has been utilized to set up a mathematical model for oil supply system. Individual lubrication elements of the oil supply system, such as propeller- installed oil cap, oil galleries, radial oil feeding holes, spiral oil grooves, and various sliding surfaces have been analogized by equivalent electric elements, and these have been combined together to form an electric circuit corresponding to the whole oil supply system. By solving the closed network equations of the model, oil flow rates at various lubrication elements could be obtained. Total amount of the oil flow rate drawn into the shaft has been measured and compared reasonably well with the prediction of the numerical simulation.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.160-166
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• 1999

Nonlinear characteristics of the hydrodynamic journal bearing with circumferentially groove are analyzed numerically considering cavitation region, when an external sinusoidal shock is given to the system. The oil film force is obtained by solving the finite width universal Reynolds equation at each time step. Frequency response function and journal orbit obtained from both linear and nonlinear bearing simulations are compared with each other. The vibration response of the journal is different from the expectation obtained from the linear analysis as increase the vibration amplitude of external disturbance. Therefore, the linear theory is not adequate, and the nonlinear calculation such as used in this research is needed to design safety rotor systems.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.10a
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• pp.117-119
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• 2014

해상교통관제(VTS, Vessel Traffic Service) 구역에서는 선박의 항해뿐만 아니라 준설, 급유, 수상레저, 어로, 군사훈련, 모래 채취 등 다양한 해양 활동이 동시에 이뤄지고 있다. 이들 활동들은 제한된 공간에서 경쟁적으로 이뤄지기에 시 공간적 충돌을 수반하게 된다. 최근 VTS는 '해상교통서비스' 라는 본연의 역할과 더불어 다양한 해양 활동들이 조화롭게 이뤄지도록 조율하는 영역까지로 확대되고 있다. 이렇듯 발전하는 VTS의 역할에 발맞춰 관제 구역에도 해양공간계획(MSP, Marine Spatial Planning) 개념을 도입하여 체계적인 접근이 필요하다. 본 연구에서는 해양공간계획을 도입한 타 국 사례를 소개하고 그 도입 필요성에 대해 제안 하고자 한다.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1966-1968
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• 2000

Globally, oil-filled paper-insulated cables and cross-linked polyethylene-insulated cables have been mainly applied for a underground power transmission line. The oil-filled cable has the hydraulic system in which insulating oil, expanded and contracted by temperature changes, is absorbed and supplied. This system enable us to detect oil leakages from the cable. But it has some problems such as difficulty in detecting minor leakages and a relatively long period of fault detecting. And so, this paper introduce a new leakage detection system, improved from the current one.