• Journal of Korean Society for Atmospheric Environment
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• v.31 no.1
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• pp.1-14
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• 2015

This study investigates the impact of enhanced regional meteorological fields on improvement of wind energy forecasting accuracy in the southwestern coast of the Korean Peninsula. To clarify the effect of detailed surface boundary data and application of analysis nudging technique on simulated meteorological fields, several WRF simulations were carried out. Case_LT, which is a simulation with high resolution terrain height and land use data, shows the most remarkable accuracy improvement along the shoreline mainly due to modified surface characteristics such as albedo, roughness length and thermal inertia. Case_RS with high resolution SST data shows accurate SST distributions compared to observation data, and they led to change in land and sea breeze circulation. Case_GN, grid nudging applied simulation, also shows changed temperature and wind fields. Especially, the application of grid nudging dominantly influences on the change of horizontal wind components in comparison with vertical wind component.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.3
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• pp.72-77
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• 2014

The cross-section area of cable in the Offshore Wind Farm (OWF) is smaller than that in the onshore wind farm. Because the power loss in OWF is large relatively, the power loss is a key element for the economic evaluation of OWF design. The availability of wind turbine in OWF and the size of OWF are larger than those of onshore wind farm. If the economic evaluation of OWF ignores the availability of wind turbines, the power loss cost of OWF is overpriced. Since there are so many wind turbines, also, the calculation of power loss should be more accurate. In this paper, a method to calculate power loss is proposed for the design of big and complex inner-grid in OWF. The 99.5MW OWF is used for case study to see what effect the proposed method have on the power loss cost.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.11
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• pp.89-95
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• 2013

In resent years, Offshore Wind Farm (OWF) is being actively developed. Typically, OWF has a better wind resource than onshore one, but also have a very high investment cost and maintenance cost. Furthermore, due to a difficulty of geographical access, OWF can be affected by the failure for a longer time. As the result, OWF has a higher loss cost. Therefore, a reliability evaluation should be performed more carefully at OWF planning stage. In this paper, a methodology for the reliability evaluation on inner grid is suggested. Inner grid connects wind turbines via submarine cables and transfers power to offshore substation. According to location of the faulted cable under layouts of inner grid, the transfer ability of inner grid is influenced. In order to indicate the transfer ability of inner grid, several indices are introduced such as PNDR, EEND and EENDC. To demonstrate the methodology described in this paper, diversity case studies were performed.

• Journal of Environmental Science International
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• v.23 no.6
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• pp.1085-1093
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• 2014

We investigate the amount of potential electricity energy generated by wind power in Busan metropolitan area, using the mesoscale meteorological model WRF (Weather Research & Forecasting), combined with small wind power generators. The WRF modeling has successfully simulated meteorological characteristics over the urban areas, and showed statistical significant to predict the amount of wind energy generation. The highest amount of wind power energy has been predicted at the coastal area, followed by at riverbank and upland, depending on predicted spatial distributions of wind speed. The electricity energy prediction method in this study is expected to be used for plans of wind farm constructions or the power supplies.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.8
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• pp.83-89
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• 2015

This study suggests the methodology to decide the number and adequate capacity of substation transformer in a large-scale offshore wind farm (OWF). The recent trend in transformer capacity of offshore substation is analyzed in many European offshore wind farm sites prior to entering the studies. In order to carry out the economic evaluation for the transformer capacity we present the cost models which consist of investment, operation, and expected energy not supplied (EENS) cost as well as the probabilistic wind power model of wind energy that combines the wind speed with wind turbine output characteristics for a exact calculation of energy loss cost. Economic assessment includes sensitivity analysis of parameters which could impact the 400-MW OWF: average wind speed, availability, discount rate, energy cost, and life-cycle.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.553-560
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• 2020

This paper presents an algorithm for identifying and eliminating errors by seagrasses in coastal bathymetry surveying using drone and HD camera. Survey errors due to seagrasses were identified, segmentated and eliminated using a L∗a∗b color space model. Bathymetry survey using a drone and HD camera has many advantages over conventional survey methods such as ship-board acoustic sounder or manual level survey which are time consuming and expensive. However, errors caused by sea bed reflectance due to seagrasses habitat hamper the development of new surveying tool. Seagrasses are the flowering plants which start to grow in November and flourish to maximum density until April in Korea. We developed a new algorithm for identifying seagrasses habitat locations and eliminating errors due to seagrasses to get the accurate depth survey data. We tested our algorithm at Wolpo beach. Bathymetry survey data which were obtained using a drone with HD camera and calibrated to eliminate errors due to seagrasses, were compared with depth survey data obtained using ship-board multi-beam acoustic sounder. The abnormal bathymetry data which are defined as the excess of 1.5 times of a standard deviation of random errors, are composed of 8.6% of the test site of area of 200 m by 300 m. By applying the developed algorithm, 92% of abnnormal bathymetry data were successfully eliminated and 33% of RMS errors were reduced.

• JOURNAL OF ELECTRICAL WORLD
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• s.323
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• pp.69-75
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• 2003

불투명한 경제정세의 와중에서도 전기에너지를 지탱하는 근간이 되는 파워 일렉트로닉스 분야는 확실히 그 기술개발을 향상시켜 오고 있다. 특히 파워디바이스는, 지구환경과 생활환경을 보다 쾌적하게 하기 위하여 인버터 장치 등의 각종 전력절약기기와 풍력$\cdot$태양광$\cdot$연료전지 등 클린에너지의 전력제어장치에 없어서는 안되는 반도체디바이스로 성장했다. 파워디바이스 중에서도 IGBT(Insulated Gate Bipolar Transistor)의 기술혁신은 요 20년 사이에 비약적인 성과를 거두었다. 1980년대에 제품화된 IGBT는, 반도체메모리의 초미세가공기술을 도입하면서 $5{\mu}m$에서 서브미크론의 디자인툴로 발전하여, 2000년대에 들어 칩의 전류밀도는 약 2배, 포화전압은 약 $65\%$까지 개량되었다. 이와 같은 IGBT의 변천은, 전력손실을 대폭적으로 저감시켜 에너지절약기기의 전력변환효율 향상에 공헌하고 있다. 파워디바이스의 기술진보에서 또 한 가지 잊지 말아야 할 것은 주변회로의 집적화(集積化)에 의한 고성능$\cdot$고기능화이다. 최근의 인버터용 파워디바이스로 가장 많이 사용되고 있는 파워모듈은, IGBT등의 파워칩과 그 주변회로와의 컬래버레이션에 의한 제품이다. 다시 말하면 구동회로, 전류$\cdot$전압$\cdot$온도센서 및 그것들의 보호회로가 IC(집적회로)에 편입되어 고기능$\cdot$소형화를 촉진시키고 있다. 구동회로는 LVIC (저전압집적회로)에서 HVIC(고전압집적회로)로 발전하여 전류$\cdot$온도 등의 각종 센서도 동일 칩에 설계할 수 있게 되었다. 또 센싱이나 보호기능뿐만이 아니라 출력전류의 제어를 위한 연산기능과 di/dt의 제어기능이 내장되도록 되어 있어 보다. 고성능의 인텔리전트 파워모듈(IPM)이라고 불리우는 새로운 개념의 파워디바이스가 실현되었다. 또한 패키지 기술도 내부배선 인덕턴스의 저감과 트랜스퍼 몰드패키지의 개발로, 소형화뿐만이 아니라 파워칩의 성능$\cdot$기능을 충분히 발휘할 수 있도록 개발이 적극적으로 추진되고 있다.

• Journal of Energy Engineering
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• v.20 no.1
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• pp.8-12
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• 2011

For reducing greenhouse gas emissions, the short-term strategy is of existing energy-efficient appliances to facilitate the spread of energy efficiency improvements to improve energy efficiency, energy saving projects that will include investments to enable. R&D is at the core of the long-term strategy. To reduce energy demand, the equipments and processes improved energy efficiency should be developed. In terms of energy supply, the policies for greenhouse gas reduction is to replace fossil fuels by expanding the supply of renewable energy such as solar, wind, geothermal, biomass and nuclear power as nearly zero-emission of greenhouse gas. In terms of energy consumption, measures to reduce greenhouse gas emissions is in line with the policy for efficiency improvement. The buildings & work-site of high-energy consumption in the building & Industry sectors, should implement a policy to strengthening the voluntary agreement on energy-saving facilities and expand to invest in energy saving facilities.

• The KIPS Transactions:PartD
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• v.10D no.3
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• pp.531-540
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• 2003

Because of the rapid increase of energy consumption, we have some problems such as environmental pollution, global warming, the oil shocks, and so on. To solve these problems, concern about renewable energy such as solar energy, wind force, and water energy is continuously increasing. America, Europe, and Japan have developed a system that manage and utilize the information of the renewable energy resources. However, in the domestic, renewable energy information system was not effectively built yet. Therefore, in this paper, we propose a renewable energy information system, which store and manage solar radiation energy data. We implemented the system using ArcView GIS. Also the system is able to retrieve the information from the energy database through various spatiotemporal queries. In addition, user can identify the results of summary data in the form of chart, graph, and counter line. The implemented system is supplied to the user through the web by ArcIMS.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.5
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• pp.389-395
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• 2017

This paper showed the difference in the optimum conditions by using the ANSYS CFX simulation program with the changes of the main-blade angle and sub-blade angle. Main-blade Shape 4,which had angle $45^{\circ}$ while other Shapes with angle $0^{\circ}$, was increased to 157.2[%] to 263.2[%] in the power and was increased to 110[%] to 250[%] in the power coefficient. Moreover, when the Shape 5 Fin length of main-blade doubled, the power was 70.8[%] when compared with Shape 1 and 27.5[%] with shape 4.If the main-blade geometry equals shape 1 in the case structure, The power of Case1 was increased to 13.3[%] when compared with Case2. Also, the power coefficient was increased to 15.4[%]. When sub-blade angle was $45^{\circ}$, main-blade was better than the Fin type than the Bended type. The power of Case4 was increased to 47[%] when compared with Csae1 and increased to 13.6[%] with Case 3. Also, the power coefficient was 46.7[%] when compared with Case 1 and 15.8[%] with Case 3.