• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1123-1128
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• 2008

Marine facilities like buoy, lighthouse are operated with stand alone power supply system. This power system can consist of a stand-alone type power system such as PV(Photovoltaic) system, wave system or hybrid system which is not cooperated with a commercial power system. Generally, PV power system for marine facilities can not supply a sufficient power to buoy, because it is so influenced from weather condition. For solving this problem the hybrid power system with PV and wave is studied on a various area, that is why a hybrid power system is requires to overcome these problems. This paper will describe a generation characteristic of WEC(Wave Energy Converter) for buoy, and an AFS(Anti-Fouling System) influence on WEC.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.50.2-50.2
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• 2010

Magnetic helicity injection in 28 solar active regions producing 46 CMEs was investigated to find its relationship with the occurrence and speed of CMEs. The helicity injection in the active regions under investigation was calculated using full-disk 96 minute MDI magnetograms. The major findings of this study are as follows. First, the 46 CMEs are categorized into two different groups by two characteristic evolution patterns of helicity injection in their active regions: (1) a monotonically increasing of helicity accumulation (Group A; 30 CMEs in 23 active regions) and (2) significant helicity injection followed by its sign reversal (Group B; 16 CMEs in 5 active regions). Second, a fairly good correlation between the helicity injection rate and the CME speed is found for the 30 CME events in Group A. Further statistical studies, however, are needed to check whether the two characteristic helicity patterns are shown in other CME-productive active regions.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.8
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• pp.1226-1231
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• 2009

In this paper, a solar-wind hybrid system is decsribed for Stand-Alone(SA) power generation system. Mostly SA power generation system for ocean facilities composes a solar system. Normally, the output power of solar system is decreased with weather condition as cloudy and rainy. Solar-wind hybrid system can be operated as complement system each other. In this paper, the characteristic simulation of solar and wind is performed by LabVIEW. The hybrid power generation system is designed according to simulation results, and is tested for checking the complement characteristic.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.3
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• pp.230-240
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• 2022

In general, a high tension on the anchor and chain is placed when a ship at anchor is subjected to heavy weather. Mariners have to pay attention to whether dragging anchor occurs to keep the safety of the ship at anchorage since it is difficult to maintain the stable motion of ship and it causes collisions with other ships nearby. In this paper, the ship motion against the external forces was shown to obtain the fundamental data about characteristic of holding power due to nature of seabed at anchor, so practical trials were carried out in rocky area and muddy area using a trial ship around coastal area of South Korea. In muddy seabed, holding power showed reasonable tension values depending on the distance from anchor position of continuing swing motions of a ship corresponding to wind force. Meanwhile in rocky seabed, tension values on the chain appeared very high occasionally regardless of the distance from the anchor position and seemed to exceed its holding power to be the breaking strain of the chain although weather was not in a severe condition. Therefore, some of the cables laid on the seabed were presumed to be caught in a crack on the rock. It is assumed that even a small amount of external force may cause the chain to break in a moment in rocky seabed. Additionally, wind and current forces had a somewhat contradictory effect on holding power of the ship between them.

• Journal of the Korean Geographical Society
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• v.39 no.1
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• pp.13-26
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• 2004

This paper examined the possibility of NET application for a relative weather stress index in Korea. The characteristic of NET distribution used temperature, relative humidity, wind speed which forecasting at Korean Meteorological Administration were analyzed. Regional critical values of daily maximum NET of stress index for summer resembled the distribution of daily maximum temperature because were not impacted wind and humidity but temperature. Regional critical values of daily minimum NET of stress index for winter distributed variously compared with summer. The highland region and the northern region of Seoul were impacted of low temperature and coastal region which strong wind. The occurrences of stressful days did not vary in summer, but obviously increased in winter after mid-1990s.

• Journal of Agricultural Extension & Community Development
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• v.23 no.1
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• pp.27-37
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• 2016

This paper estimated the demand function of the cuts of pork by using the consumer panel and the weather data from the Korea Meteorological Administration with a log-log model and AIDS model. The results show that the price elasticity of demand for cuts of pork is high in the sequence of arm shoulder, leg, special cuts, tenderloin, blade shoulder. In contrast, spare rib, belly and loin are classified as low price elasticity of demand. The income elasticities of demand for leg and blade shoulder are 11% and 7.6% respectively. The loin is classified as inferior goods, because demand decreases when income increases. The results also demonstrate show that the demand increases highly in the sequence of loin, arm shoulder, spare rib, belly if housewife is older, and the demand of belly increases when family number increases. Belly substitutes every cut except spare rib, and tenderloin substitutes special cuts. Spare rib, on the other hand, does not substitute other cuts. In addition, job status, family member, husband job, purchasing place, consumer characteristic, eating-out times, purchasing time, and weather are statistically significant.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1081-1082
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• 2008

Photovoltaic (PV) power generation system has been widely studied as a clean and renewable power source. The purpose of this study is to keep the output power of photovoltaic cells maximum under any weather conditions. There are so many MPPT (Maximum Power Point Tracking) methods. P&O method has been used as a key MPPT method, both voltage and current coming out from PV array have to be feedback in the method. Thus, the system has a complex structure, and may fail to track MPP of PV array when unexpected weather conditions happen. In order to reduce the feedback components, POS MPPT control method was proposed by the authors. In this paper, the authors apply the POS MPPT control method to three phase PCS system. And the effectiveness of the proposed control scheme is demonstrated through PSCAD/EMTDC simulation.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.2 no.3
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• pp.1-9
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• 1999

This paper described the results of the characteristics of the near-bottom flow and field analysis of the tidal flats sediment. It was the aim of this paper to grasp current flow of tidal flat's environment and influence factor for environmental change forecast of tidal flats. Field measurement of water velocity, water elevation, bed materials test, and temperature distribution of tidal flat were conducted. Thereafter, current flow, turbidity and temperature distribution of tidal flat sediment have been discussed. The field research results showed that the fluctuating velocity near the seabed before and after its appearance at low tide was strongly affected by the wind wave. The resuspension of the sea-bottom sediment took place with great intensity before and after the appearance of the seabed at low tide. Both the sea water level and the weather condition were a significant influential factors. Such as, temperature and turbidity just on the surface and the shallow layer of seabed sediments were varied largely with time and weather conditions, but that its deeper layers was almost constant. Temperature on the seabed sediments was strongly influenced by irradiance and water depth. The temperature variation of the tidal flat and the variation characteristics of the current flow and turbidity depend greatly on the inhabiting environment of the tidal flat benthic organism.

• Journal of the Korean Solar Energy Society
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• v.31 no.6
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• pp.72-77
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• 2011

The purpose for installation of offshore weather station is a measurement of wind resources and so on. If weather station is operated, it will be possible to analysis for wind resource and arrangement of wind farm by using measured data. In this paper, we carried out the development of offshore wind resource measurement system for measuring offshore wind resource. Also, In order to monitor for real-time wind data with 1 Hz, we installed the wireless transmission system. All wind characteristic data are sent to the server PC through the this system is connected outport of DataLogger. Transmitted wind data were used in order to look at in the Web-page and tablet PC on a real time basis in a graph. In this paper, we will introduce about the wind resource measurement and remote monitoring system that is the result of study.

• Journal of Navigation and Port Research
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• v.29 no.9
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• pp.777-782
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• 2005

Maritime transportation consists of various situations such as navigation in the ocean, ship handling at harbor entrances, cargo handling and mooring in harbors. Generally, ships are built for the purpose of currying people and materials upon the seas. In order to accomplish the mission, a ship must be built to withstand the rigors of heavy weather and waves. In particular, the safety of ship motions at the entering/departing harbor and mooring under the effects of waves is very important for ship operation from the viewpoint of marine engineering. Therefore, safety and efficiency during entrance, departure, and mooring are extremely important aspects in the evaluation of ship operations from viewpoints of ship motions. However, the ship motions near a harbor entrance are not observed or studied as much. In this paper, to evaluate the difficulty of ship operations, field observations were performed using a new observation system with high accuracy in typhoon seasons, and grasp was done concerning about the time series characteristic that ship motions change rapidly within a harbor. Namely, such observations enable the quantitative safety evaluation under the effects of waves during ships entering and departing harbors in heavy weather.