• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.237-238
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• 2006

Vibration incidents hardly happen when a turbine generator usually installed in LNG carrier is operated, different from diesel engine generator. The purpose of this paper is to introduce an actual vibration incident, which hardly occurred in case of turbine generator, and describe all possible countermeasures to prevent from vibrations during operation.

• Nuclear Engineering and Technology
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• v.33 no.4
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• pp.397-408
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• 2001

A marine reactor shows very different thermal-hydraulic characteristics compared to a land- based reactor. Especially, study on the variation of flow field due to ship motions such as inclination, heaving and rolling is essential since the flow variation has great influence on the reactor cooling capability. In this study, the natural circulation characteristics of integral type marine reactor with modular steam generators were analyzed using computational fluid dynamics code, CFX-4, for inclined conditions. The numerical analyses are performed using the results of natural circulation experiments for integral reactor which are already conducted at Seoul National University. From the results, it was found that the flow rate in the ascending steam generator cassettes increases due to buoyancy effect. Due to this flow variation, temperature difference occurs at the outlets of the each steam generator cassettes. which is mitigated through downcomer by thermal mixing. Also, around the upper pressure header the flow from descending hot leg goes up to the ascending steam generator cassettes due to large natural circulation driving force in ascending steam generator cassettes. From this result, the increase of How rate in the ascending steam generator cassettes could be understood qualitatively.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.9
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• pp.100-107
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• 2013

Since the West Sea experiences a big difference in tides, the output power of the small marine hydroelectric power plant varies with the tide. When an induction generator is used here for small hydroelectric power, the reactive power capacitor should be installed at the generator main bus to compensate for the changes in power. As such, the sizing method for the power compensation of the induction generator is reviewed and an optimal method for compensation is suggested. The self-excitation minimum capacitor capacity method, which prevents high voltages, and the power factor automatic control method, which retains a power factor of greater than 90% are reviewed. The compensation effect of reactive power is confirmed through a case study.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.6
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• pp.1017-1025
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• 2004

Generally generator is connected to the bus with no load. After the connection to the bus. the frequency of generator system with no load has to be increased for preventing the reverse power. But in a few case of parallel running with infinite bus system, we have to synchronize the loaded generator to the infinite bus. The frequency of generator system with load has to be lowered for prevention of load shift to the bus system. The blackout of infinite bus decreases the parallel running generator's frequency because of load increasing. In this paper we propose a method that the generator with load maintains the frequency constantly after the blackout of infinite bus. With the constant speed control and load control method of parallel running system to the infinite bus we apply the method to the industrial generating system.

• Journal of Advanced Marine Engineering and Technology
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• v.15 no.2
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• pp.53-63
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• 1991

This study suggests a new type shaft generator driven by hydraulic power suitable for small size vessels. Since the shaft generator system is very easy to be affected by disturbances such as speed variation of main engine and load variation of the generator, a robust servo control must be implemented to obtain stable electric power with constant frequency. Thus, in this study two types of controller design method-the reference following optimal control method and robust servo control method-are adopted to the controller design. In the experiment, static and dynamic characteristics of the shaft generator system according to the variation of input frequency setting, the speed variation of the pump and the load variation of the generator are investigated. From the considerations on the computer simulation results and experimental results, it is ascertained that the shaft generator system proposed in this study has good control performances.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.10a
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• pp.75-75
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• 2011

This paper has been studied that ocean wave vibration power generator is composed of buoy and vibration generator to make effective use of ocean wave energy. We designed buoy to can occur resonance for dominant frequency with ocean wave. And then we fitted the natural frequency of vibration system with vibration power generator to buoy's natural frequency. And we can show that the amplitude of ocean wave up and down motion is decreased, on the other hand, the displacement of vibration system with vibration power generator is increased. Therefore, ocean wave vibration power generator which is proposed in this paper has merits not only securing its stability from surroundings but also producing more electronic power by using ocean wave energy.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.4
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• pp.1-12
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• 1994

Most merchant ships are supplied with the only essential fresh water from a port for economical cargo transportation and the reduction of a nevigation expense. And the deficient fresh water for a voyage is produced by fresh water generator with the various exhaust energy generated in the engine room on a voyage. At present, an evaporation type fresh water generator are extensively used on ship because the operating cost of it is lower than that of a reverse osmosis pressure type. This study introduce a development results on the large evaporation type fresh water generator enable to be used for large merchant ships. It is accomplished the performance test using the developed large fresh water generator.

• Journal of Drive and Control
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• v.12 no.2
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• pp.7-13
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• 2015

In this study, we suggested the wave power generator using horizontal motions of the wave for use in the coastal sea. The length of the horizontal movement of the wave in the vicinity of the sea surface is larger than the length of the vertical reciprocating movement of the wave, hence the proposed device has a wave power transmission plate. In addition, because the motion of the wave is maximum to the sea surface, by arranging the buoyancy tanks at the top of the wave power transmission plate, it is always capable of vertical movement in accordance with the sea surface. To confirm the usefulness of the proposed wave power generator, we constructed a mathematical model of the wave power generator and carried out simulation using bondgraph. Furthermore, the efficiency was verified by measuring the degree of electrical energy production through a preliminary experiment.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.4
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• pp.403-408
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• 2014

Lots of electric power has been wasted through the load bank usually in the container boxes during the generator load test of the ship and offshore plant in the new ship building. Therefore in this research, the quantity of wasted electric power through generator load test under construction was investigated on big shipbuilding yard and quantity of electric power that can be recovered is analyzed when produced electric power during the generator load test is connected to KEPCO Grid, according to laboratory's experiment result where recovers electric power produced from small generator connected to KEPCO Grid.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.4
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• pp.502-508
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• 2009

To obtain high power, diesel engines continuously increase combustion pressure and mean effective pressure each cylinder, and the excitation sources and noisy sources are increased, too. Moreover, to reduce the costs, shipyards make hull structures weaker than before. As above reasons, it is more difficult to control the vibration phenomenon nowadays. In this study, it was investigated why diesel generator sets reached the vibration allowable limits during the FAT and heavy vibration phenomenon of diesel generator sets using ODS test during onboard tests. Also, it is found out the stiffness of deck and common bed using the test result of their structural impedance. To find out the vibratory characteristics of diesel generator sets, model tests were carried out. From the sensitivity analysis after above tests, it was selected points to be reinforced and studied troubleshooting to solve heavy vibration phenomenon of diesel generator sets.