• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.300-301
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• 2015

Accurate and robust load forecasting model plays very important role in power system operation. In case of short-term electric load forecasting, its results offer standard to decide a price of electricity and also can be used shaving peak. For this reason, various models have been developed to improve accuracy of load forecasting. This paper proposes a newly forecasting model for weather sensitive season including temperature and Cooling Degree Hour(C.D.H) data as an input. This Forecasting model consists of previous electric load and preprocessed temperature, constant, parameter. It optimizes load forecasting model to fit actual load by PSO and results are compared to Holt-Winters and Artificial Neural Network. Proposing method shows better performance than comparison groups.

• 설비공학논문집
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• 제23권2호
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• pp.147-152
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• 2011

The cryogenic cooling load from the top plate of cryostat to liquid helium surface, including wall conduction, thermal radiation and current leads, is investigated in a closed cryostat system for superconducting magnet. In general methods of load estimation, individual load is calculated separately, however they are actually coupled each other because of natural convection of helium vapor. Using relevant heat transfer analysis, we calculate cryogenic load with taking into account the effect of natural convection. Cryogenic load is under-estimated approximately 1% when the natural convection is ignored. The difference between actual cooling load and cooling load by individual calculation increases with supplying current.

• 대한전기학회논문지:전력기술부문A
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• 제53권2호
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• pp.87-96
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• 2004

This paper summarizes the research results of the load management for pole transformers done in 1997-1998 and 2000-2002. The purpose of the research is to enhance the accuracy of peak load estimation in pole transformers. We concentrated our effort on the acquisition of massive actual load data for modifying the load regression coefficients, which related to the peak load estimation of lamp-use customers, and adjusting the demand-factor coefficients, which used for the peak load prediction of motor-use customers. To enhance the load regression equations, the 264 load data acquisition devices are equipped to the sample pole transformers. For the modification of demand factor coefficients, the peak load currents are measured in each customer and pole transformer for 13 KEPCO (Korea Electric Power Corporation) distribution branch offices. Case studies for 50 sample pole transformers show that the proposed coefficients could reduce estimating error of the peak load for pole transformers, compared with the conventional one.

• KEPCO Journal on Electric Power and Energy
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• 제5권1호
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• pp.17-24
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• 2019

본 논문은 전력계통의 부하 모델이 단기 전압 안정도 해석 결과에 미치는 영향을 분석하였다. 우선, 본 논문에서는 일반적으로 많이 사용되는 부하 모델을 소개하였고, 일부 부하 모델은 모델 파라미터를 최적화하더라도 실제 측정된 계통 현상을 재현할 수 없다는 것을 확인하였다. 또한, 본 논문에서는 상정사고 상황을 고려하여 국내 전력계통의 단기 전압 안정도 해석 시 부하 모델의 영향과 지역별 부하 모델의 영향성을 검토하였다. 해당 결과를 통해 부하 모델 선정의 중요성을 재차 확인할 수 있었으며, 상정사고 인근 지역의 부하 특성을 보다 더 정확하게 반영해야 함을 알 수 있다.

• 전기학회논문지
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• 제57권11호
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• pp.2061-2065
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• 2008

In the conventional operation of ice-storage system based on operator's experience and judgement, the failure in forecast of cooling load occurs frequently due to operator's misjudgement and unskilled operation. This study presents the method of constructing self-organizing fuzzy models which forecast tomorrow temperature, humidity and cooling load periodically for economic and efficient operation of ice-storage system. To check the effectiveness and feasibility of the suggested algorithm, the actual example for forecasting temperature, humidity and cooling load of ice- storage system in KEPCO training institute, Sokcho, is examined. The computer simulation results show that the accuracy of temperature, humidity, cooling load forecast of the suggested algorithm is higher than that of the conventional methods.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
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• pp.869-871
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• 1998

The extensive use of composite insulators for transmission lines can ultimately be justified only on long-term qualification tests. The actual load working on the insulator in the field is not static load but cyclic load. So in this paper, we discussed an examination of aging degradation by mechanical performance of composite insulators under static tension load and cyclic tension load. and also described useful approaches for analyzing their long term performance so as to develop reliable composite insulators. The static and cyclic tension load-time test data were examined by Weibull distribution for their capability of presuming long term performance. It was found that cyclic tension loads were more severe than static tension loads. The results also indicate that it may be relevant for an user to select composite insulators on basis of their performance under cyclic tension loads than static tension loads.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 봄 학술발표회 논문집
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• pp.598-604
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• 1997

In recent years, strengthening by epoxy-bonded steel plates, carbon fiber sheets, aramid fiber sheets and so on, is spotlighted. Among them, the method using steel plates is most widely applied. Most studies have dealt with strengthening by epoxy-bonded steel plates. However the actual behavior of strengthened RC beams are not well established. Particularly, the studies on the separation load thar affects failure load of the beam are relatively insufficient. In this study, test parameters are the magnitude of pre-load, plate length, plate thickness, existence and spacing of anchor bolt, the number of plate layer and the height of side strengthening, 17reinforced concrete beams are strengthened by steel plates according to test parameters. Deflection, failure load, strains of reinforcing bar, concrete and plate are measured from tests(4 points loading). The failure mode, and separation load are analyzed from these measured data. The difference between Robert's theory and test results is discussed, and the prediction equation for separation load in the case of rip off is proposed.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 추계학술대회
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• pp.720-722
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• 2009

경제 성장에 따른 국내 산업분야의 발달 및 국민 생활수준의 향상으로 전력 소비가 지속적으로 증가하고 있다. 전력을 안정적으로 공급하기 위해서는 전력 수요에 대한 중 단기 예측이 중요하며, 정확한 예측에 따라 안정적인 수급 계획을 확립할 수 있다. 본 논문에서는 부산시에서 공급되는 부산지역의 전력 데이터와 기후 관련 자료를 1995년 1월부터 2007년 12월까지의 측정치를 가지고 시계열 데이터를 수집하여 분석하고 신경회로망의 구조를 설계하여 실험을 통하여 실제 데이터와 예측 데이터를 비교 분석하고 평가한다.

• 한국물환경학회지
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• 제26권4호
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• pp.598-607
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• 2010

One of constraints in the application of unit-load method to estimate non-point pollution loads in the total water pollutant load management system (TWPLMS) is the limited numbers of applicable unit-loads. Since only 7 unit-loads are currently available for total 28 land-use categories in the national land register data, each unit-loads inevitably have to represent several land-use categories regardless of their actual land coverage characteristics. As a way to minimize the problem, this study suggested a nested application of the available unit-loads based on the analysis of high resolution aerial images taken in the Kyeongan watershed. Statistical analysis of three selected land-use categories such as school, apartment complex, and golf course showed that there exit significant (95% confidence level) relationships between the registered land-uses and actual land coverages. The school and apartment complex currently considered as 100% ground have only 65% and 80% of ground characteristics, respectively. Golf course, which is considered as 100% pasture, has about 5% of ground area. This indicates that the unit-load method using in TWPLMS can give over estimated non-point pollutant loads for the school and apartment complex (19.8~54.4%) but under estimation for the golf course (80.9%).

• Structural Engineering and Mechanics
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• 제22권2호
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• pp.197-222
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• 2006

In this paper, the non-linear time-dependent closed-form, discrete and combined solutions for the post-elastic response of a geometrically and physically non-linear suspended cable to a uniformly distributed load considering the creep effects, are presented. The time-dependent closed-form method for the particularly straightforward determination of a vertical uniformly distributed load applied over the entire span of a cable and the accompanying deflection at time t corresponding to the elastic limit and/or to the elastic region, post-elastic and failure range of a suspended cable is described. The actual stress-strain properties of steel cables as well as creep of cables and their rheological characteristics are considered. In this solution, applying the Irvine's theory, the direct use of experimental data, such as the actual stress-strain and strain-time properties of high-strength steel cables, is implemented. The results obtained by the closed-form solution, i.e., a load corresponding to the elastic limit, post-elastic and failure range at time t, enable the direct use in the discrete non-linear time-dependent post-elastic analysis of a suspended cable. This initial value of load is necessary for the non-linear time-dependent elastic and post-elastic discrete analysis, concerning incremental and iterative solution strategies with tangent modulus concept. At each time step, the suspended cable is analyzed under the applied load and imposed deformations originated due to creep. This combined time-dependent approach, based on the closed-form solution and on the FEM, allows a prediction of the required load that occurs in the post-elastic region. The application of the described methods and derived equations is illustrated by numerical examples.