• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.212-215
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• 2003

In this paper, a model pole transformer was designed to improve the reliability of pole transformers and its short circuit withstand strength was tested. The failure causes of the pole transformers which had been operated in the field were analyzed and several patterns of the causes were determined. A novel countermeasure was devised to prevent the failures of the pole transformers in advance. A model pole transformer was designed and made in accordance with the given specifications to strengthen the short circuit withstand capability and its characteristic was tested. As a result, the advanced performance of the model pole transformer was confirmed and novel techniques in manufacturing process was suggested. It is considered that all the methods employed in the developing process will be helpful to design and manufacture the pole transformers thus the reliability of pole transformers in distribution lines will be improved.

• 전기학회논문지
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• 제57권9호
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• pp.1507-1515
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• 2008

It is essential for electric power companies to have a quick restoration system of the faulted pole transformers which occupy most of transformers to supply stable electricity. However, it takes too much time to restore it when a transformer is out of order suddenly because we now count on operator in investigating causes of failure and making decision of recovery methods. This paper presents the concept of 'Fault pattern analysis and Restoration prediction model using Data mining techniques’, which is based on accumulated fault record of pole transformers in the past. For this, it also suggests external and internal causes of fault which influence the fault pattern of pole transformers. It is expected that we can reduce not only defects in manufacturing procedure by upgrading quality but also the time of predicting fault patterns and recovering when faults occur by using the result.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.607-612
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• 2002

This paper presents the first domestic model product of hybrid Insulation low-loss type pole transformer, with increased overload ability, increased life, reduced loss, focusing improved short-circuit characteristics. The capacity of this transformer is 100 KVZ, rates first voltage 13200 V and secondary voltage 230/115 type. The volume of model transformer that was produced in high temperature using hybrid insulation can be reduced to 10-20% in comparison with that of present transformer with the same capacity. In this paper, we did short-circuit test and tested general characteristics of model transformer. In addition, we suggested design application new concept and methods thorough this experiment.

• 한국전기전자재료학회논문지
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• 제14권4호
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• pp.297-301
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• 2001

In this paper, the temperature distribution and thermal stress analysis of 50kVA pole cast resin transformer for power distribution are investigated by FEM program. The one body molding model (Model 1) and air duct model (Model 2) are designed and their temperature distribution are analysed. The temperature rise value is about 105.5 deg in the model 1 and 65.28 de in the model 2. The temperature change of secondary winding is more than primary winding according to load ratio. The concentration part of Von Mises Stress occurs at interface between glass fiber and epoxy.

• 조명전기설비학회논문지
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• 제21권7호
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• pp.84-93
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• 2007

주상변압기는 고객에게 직접 전력을 공급하는 설비로서 전력공급의 안정성확보를 위한 중요한 기자재 중 하나이다. 하지만 제조결함에 의한 3년 이내의 초기고장 또는 13년이 초과 사용한 후의 열화고장이 빈번히 발생하고 있어 변압기 품질분석을 통한 신뢰성이 개선된 주상변압기 개발이 필요하다. 본 논문에서는 열적, 기계적, 전기적으로 성능이 향상된 새로운 모델의 혼합절연 주상변압기를 개발하였다. 변압기의 기계적, 열적특성을 향상시키기 위한 혼합절연 방식에 대한 설계 및 제작방법을 제시하고 과부하시험을 시행하여 순간최대부하에 대응할 수 있도록 과부하내량 160[%] 까지 증가시킬 수 있음을 확인하였다. 또한 본 논문에서는 100[kVA] 1대를 시제품으로 제작하여 단락강도시험과 변압기 관련 절연시험을 시행하여 전자기계력의 분석과 단락강도설계 향상 방안에 대하여 설명하고 이와 관련하여 연구한 결과에 대해 논하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.276-278
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• 1999

In this paper, we analyze customers' working electric energy (kWh) which is served pole-transformer in order to reduce peak load current error which is generated in application load correlation equation. The characteristic of electric load which customers are using is classified by customer's working electric energy (kWh) and ratio of cooling equipment possession. For the input data of fuzzy model, we used to kWh on April which represents basic load and kWh which is increased from April to August. The April kWh is used to classify into large, medium, small customer. Also, the increased kWh is used to know information of cooling equipment possession. For the output value of fuzzy model, we can determined peak load current limit in application load correlation equation.

• 전력전자학회논문지
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• 제22권2호
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• pp.102-108
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• 2017

Proper design guides are proposed for a practical dual-active bridge (DAB) converter based on the mathematical model on the steady state. The DAB converter is popular in bidirectional application due to its zero-voltage capability and easy bidirectional operation for seamless control, high efficiency, and performance. Some design considerations are taken to overcome the limitation of the DAB converter. The practical design methodology of power stage is discussed to minimize the conduction and switching losses of the DAB converter. Small-signal model and frequency response are derived and analyzed based on the generalized average method, which considers equivalent series resistance, to improve the dynamics, stability, and reliability with voltage regulation of the practical DAB converter. The design of closed-loop control is discussed by the derived small-signal model to obtain the pertinent gain and phase margin in steady-state operation. Experimental results of a 3.3 kW prototype of DAB converter demonstrate the validity and effectiveness of the proposed methods.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.183-183
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• 2016

Inductively coupled plasma having the high-density is often used for high productivity in the plasma processing. In large area processing, the plasma can be generated by using the multi-pole connected in parallel. However, in case of this, the power cannot transfer to plasma uniformly. To address the problem, we studied the mechanism of inductively coupled plasma connected in parallel by using transformer model. We also studied about the change of the plasma parameters over the time through the power balance equation and particle balance equation.

• Journal of Electrical Engineering and Technology
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• 제2권1호
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• pp.29-34
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• 2007

The input and output impedances in a low voltage distribution system is one of the most important matters for power line communication because from the viewpoint of communication, the attenuation characteristic of the high frequency signals is greatly caused by impedance mismatch during sending and receiving. The frequency range is from 1MHz to 30MHz. Therefore, this paper investigates the input and output impedances in order to understand the characteristic of high frequency signals in the low voltage distribution system between a pole transformer and an end user. For power line communication, the model of Korea's low voltage distribution system is proposed in a residential area and then the low voltage distribution system is set up in a laboratory. In the low voltage distribution system, S parameters are measured by using a network analyzer. Finally, input and output impedances are calculated using S parameters.

• 한국전산구조공학회논문집
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• 제27권5호
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• pp.353-360
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• 2014

본 논문에서는 국내 선박해양플랜트연구소에 구축된 빙해수조의 빙특성 중에서 모형빙의 두께와 유효탄성계수 산출과정이 소개되었다. 수조에서 결빙되는 빙판은 크기가 가로 세로각각 30 m 정도에 두께는 40mm정도이다. 모형선의 실험결과를 쇄빙선 설계에 사용하기 위하여 빙 특성 정보가 필요하다. 사람이 빙판을 일부 절개하고 일일이 손으로 두께를 측정하는 것을 지양하기 위하여 초음파 기기를 사용하였는데 저주파 장비를 사용하여 작은 샘플 모형빙에 대한 두께는 계측되었다. 하지만 완벽한 계측을 위해서는 송수신 일체형 저주파 센서나 정확한 위치가 설정된 분리형 센서 혹은 고가의 특수 장치가 필요함을 확인하게 되었다. 한편 빙판의 처짐량을 간이식 LVDT로 계측하고 이를 탄성체 위에 놓인 무한 판의 특성길이 관계식에 대입하여 빙의 유효탄성계수를 산출하였는데 외국의 결과와 유사함이 입증되었다.