• 전기학회논문지
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• 제63권2호
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• pp.197-204
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• 2014

As more and more renewable energy resources are connected into the existing power system and their generation capacities are increasing, the need for regulations to minimize their impacts on the power grid is increasingly growing. And minimizing the irregular impacts made by grid-connected wind generators is important, since the output power generated by renewable energy resources can be changed easily by the weather condition and surrounding environment. In South Korea, an operational technical standard for distributed generation is used as a regulation, in which renewable energy sources including wind power are considered as a kind of distributed generation. In this paper, an international standard, IEC 61400-21, for the grid-connected wind turbine generating system(WTGS) will be introduced and a comprehensive and detailed review on the measuring methods of power quality characteristic parameters for WTGS based on the related IEC standards will be presented. Additionally, some prerequisites for applying the international standards to KEPCO system will be proposed.

• 조명전기설비학회논문지
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• 제23권8호
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• pp.14-20
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• 2009

본 논문에서는 배전 시스템을 구성하는 기기들에 대한 설치 현황자료와 고장 자료 및 전국 지점을 대상으로 한 설문조사 자료를 이용하여 기후별 고장률을 예측하였다. 같은 종류의 배전 설비라 하더라도 그 설비가 설치되어 있는 기후 상태에 따라서 고장률은 다르게 나타날 수 있다. 그러므로 배전기기의 고장률을 설비관리나 최적 투자 계획의 운용에 사용하기 위해서는 대상 설비가 설치된 기후 특성을 고려해야 하며 이를 위해 기후 특성을 고려한 고장률 예측이 요구된다고 할 수 있다. 기후특성분석을 위하여 한국전력공사의 전국지점을 대상으로 기후 특성(호우, 낙뢰, 강풍, 해일, 특징 없음)으로 구분하여 설문조사를 실시하였고 기후 특성에 따른 영향도를 분석하였고 고장률 추정 알고리즘을 제안하였다.

• 한국지역지리학회지
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• 제10권1호
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• pp.151-157
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• 2004

1월의 clo 값은 대체로 삼지연 지역이 가장 높게 나타나고, 장전 일대의 동해안 지역이 가장 낮게 나타난다. 또한 해안 지역보다 내륙 지역이, 동해안보다 서해안이 clo 값이 높게 나타난다. 이는 지형적 영향과 기온과 풍속의 지역적 차이에 기인한다. 8월에도 삼지연, 해산 일대, 개마고원 등이 높게 나타나는데, 이는 지형적 영향으로 기온 저하와 풍속의 증가로 나타나는 현상이다. 특히 8월에는 삼지연을 중심으로 북동-남서 내륙지역으로 등치선이 만곡하고, 이 축을 중심으로 한 이외의 지역이 비교적 낮은 분포를 보인다. 이러한 원인으로는 위도, 지형 및 장마 이후의 고온 다습한 북태평양 기단의 영향과 강한 일사에 의한 지면 복사열의 방출에 있다고 사료된다.

• 조명전기설비학회논문지
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• 제20권10호
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• pp.141-150
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• 2006

본 논문에서는 폴리머피뢰기의 현장 열화인자를 인가할 수 있는 가속열화 시험장치를 제작하고 국내 환경조건을 모의할 수 있는 시험주기를 개발하여 폴리머피뢰기 완제품에 대한 장기신뢰성 평가법을 제안하였다. 그리고 가속열화시험 및 현장설치에 의한 전기적, 화학적 특성변화를 분석하여 폴리머피뢰기의 열화정도를 평가함으로써 본 연구에서 제안한 평가기법의 실효성을 검증하고 국산 폴리머피뢰기의 유지보수에 필요한 특성 데이터를 제시하였다.

• 대한한의학원전학회지
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• 제27권1호
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• pp.15-28
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• 2014

Objective : Jeol-sik, (festive seasons every 15 days based on sun cycle), refers to both Korean Traditional Festival food(jeol-sik), intertwined between months, and in-season meals(si-jeol-sik) in which the ingredients used are produced in each and one of the four season. I found that ingredients in Si-jeol-sik of Autumn are helpful for strengthening one's life force. Method : The study found that si-jeol sik for fall season has strong characteristic of casting out demons. When making songpyeon(half-moon-shaped rice cake) for Chuseok (Korean Thanksgiviing Day), they are steamed with pine needs spreaded underneath because pine needles are believed to have power in casting away evil spirits. For harvest ceremony, which were frequently held in October, people consumed steamed rice cakes garnished with red beans, which were considered to negate bad fortunes. Result : To prevent respiratory diseases caught esaily in fall due to wide daily temperature difference and dry weather, white good ingredients such as radish, pear, and taro are used. Conclusion : Main fall holidays are Chil-soek, Baek-Jung, Chu-seok. The best feature of Si-jeol-sik for fall season is that they cast out demons. Also, fall si-jeol-sik consist of many white ingredients for protecting lungs.

• 한국수산과학회지
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• 제36권3호
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• pp.306-316
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• 2003

We conducted a time-series analysis of temperature and salinity of sea water around Jeju Island, Korea. Monthly mean temperature and salinity was influenced by precipitation and weather conditions on Jeju as well as by oceanographic conditions of the open sea such as the Tsushima Warm Current and sea water in coastal areas. Salinity of Jeju coastal waters was the highest in April, and it was always over 34.00 psu with tiny fluctuation between December and June. Due to the effects of the Tsushima Warm Current, Jeju coastal waters maintained high salinity and stability. Low salinity and its large fluctuations during summer were closely associated with the China Coastal Water and precipitation in Jeju. The place of the lowest water temperature was the northeast coasts of Jeju (Gimneong, Hado, Jongdalri). In winter, as warmer water of the Tsushima Warm Current appeared in western area of Jeju dwindled flowing along the northern coasts of Jeju area and becoming cool, the lowest water temperature often appeared locally in Gimnyeong and its vicinitly in summer. The Tsushima Warm Current flows into the east entrance of Jeju Strait, but its influence is weak because of geometry and strong vertical mixing due to fast tidal currents.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제1권1호
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• pp.56-61
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• 2001

Activated sludge processes are broadly used in the biological wastewater treatment processes. The activated sludge processes are complex systems because of the many factors such as the variation of influent flowrate and ingredients, the complexity of biological reactions, and the various operation conditions. The main motivation o this research is to develop an intelligent control strategy for activated sludge process (ASP). ASP is a complex and nonlinear dynamic system owing to the characteristic of wastewater, the change in influent flowrate, weather conditions, and so on. The mathematical model of ASP also includes the uncertainty which is a ignored or unconsidered factor from process designers. The ASP model based on Matlabⓡ/Simulinkⓡ is developed in this paper. And the model performance is examined by IWA (International Water Association) and COST (European Cooperation in the filed of Scientific and Technical Research) data. The model tests derive steady-state results of 14 days. In this paper, fuzzy logic control approach is applied to handle DO concentrations. The fuzzy logic controller includes two inputs and one output to adjust air flowrate. The objective function for the optimization, in the implemented evolutionary strategy, is formed with focusing on improving the effluent quality and reducing the operating cost.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1178-1179
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• 2008

This paper describes a modeling of fixed speed wind power generation system which comprise of wind turbine, generator and grid. The wind turbine is based on MOD-2, which is IEEE standard wind turbine, and includes a component using wind turbine characteristic equation. Fixed speed induction generator is directly connected to grid, so the variation of wind speed has effects on the electrical torque and electrical output power. Therefore the power control mode pitch control system is necessary for aerodynamic control of the blades. But the power control mode does not operate at the fault condition. So it is required some methods to control the rotor speed at transient state for stabilization of wind power system. In this paper, simulation model of a fixed speed wind power generation system based on the PSCAD/EMTDC is presented and implemented under the real weather conditions. Also, a new pitch control system is proposed to stabilize the wind power system at the fault condition. The validity of the stabilization method is demonstrated with the results produced through sets of simulation.

• 전기학회논문지
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• 제57권9호
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• pp.1555-1562
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• 2008

This paper presents a cooling system using thermoelectron for improving the output of BIPV module. The temperature characteristic in regard to improving the output of BIPV system has rarely been studied up to now but some researchers only presented the method using a ventilator. The cooling system efficiency of BIPV module applied to a ventilator mainly depends on the weather such as wind, insolation etc. Because the cooling system of BIPV module using a ventilator is so sensitive, that is being set off by wind speed at all time but is unable to operate in the NOCT(Nominal Operating Cell Temperature) which is able to make the maximum output. The paper presents the cooling system using thermoelectron so as to solve such problems. The temperature control of thermoelectron can be controlled independently in the outside environment because that is performed by micro-controller. The temperature control of thermoelectron, also, can be operated around NOCT through algorism of the temperature control. Therefore, outputs of the whole system increase and the efficiency rises. The paper demonstrates the validity of proposed method by comparing the data obtained through a experiment of the cooling method of BIPV using a ventilator and proposed thermoelectron.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제12권4호
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• pp.263-269
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• 2012

The ability to characterize feature objects from radar readings is often limited by simply looking at their still frame reflectivity, differential reflectivity and differential phase data. In many cases, time-series study of these objects' reflectivity profile is required to properly characterize features objects of interest. This paper introduces a novel technique to automatically track multiple 3D radar structures in C,S-band in real-time using Doppler radar and profile their characteristic reflectivity distribution in time series. The extraction of reflectivity profile from different radar cluster structures is done in three stages: 1. static frame (zone-linkage) clustering, 2. dynamic frame (evolution-linkage) clustering and 3. characterization of clusters through time series profile of reflectivity distribution. The two clustering schemes proposed here are applied on composite multi-layers CAPPI (Constant Altitude Plan Position Indicator) radar data which covers altitude range of 0.25 to 10 km and an area spanning over hundreds of thousands $km^2$. Discrete numerical simulations show the validity of the proposed technique and that fast and accurate profiling of time series reflectivity distribution for deformable 3D radar structures is achievable.