• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.563-566
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• 1989

Drive malfunction take many forms and every possible one must be protected against. Until recently a separate analog device was needed for each type of malfunction. In this approach to simplified, more reliable motor-circuit protection and control, a microprocessor's digital controller for motor control center simultaneously examine most of the possible sources of circuit trouble and has more efficent functions (sequence control,display) than the conventional motor control center. The result of standard surge tests provided a realistic evaluation of the surge withstand capability of equipment.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1670-1672
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• 2001

In compared with air insulated switchgear GIS has a high efficiency and confidence. Insulation method using $SF_6$ gas has a very excellent insulation characteristics for high voltage equipment but has a characteristics that insulation heredity is changed for internal unequal electric field. So analysis of electromagnetic field in GIS is very important basic data for structure design and trouble diagnosis process. In compared with established method, SNM in this paper observes variation of the electromagnetic field with real time and get result very similar to measurement. In order to know the variation of electromagnetic field distribution for transient response for time and position, variations are observed when metal particles are moving fast.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1324-1326
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• 1998

To drive motor or heating machine, it needs the electric power system like the apparatus of inverter. This electric power system obviously comprises power switching devices and drivers to run them. And this system has the topology comprised one/many arm(s), - each arm has high side switching device and low side switching device. Transformer, photocoupler, and HVIC having functions of isolation and level shift which are important thing to drive high side switching device are used as component of drivers in conventional apparatus. Piezoelectric transformers are proposed in this paper, and applied to drive high side swiching device. Through experiments, the possiblities of driving high side switching device are presented and the problems are mooted concurrently. But, we also consider a counterplan for solving the mooted trouble issues.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.406-408
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• 2005

A passive Optical Network (PON) is famous for the most cost-efficient solution among the optical networks. This is because there is no active device between a central office and subscribers. A wavelength division multiplexing (WDM) offers each subscriber to feel unlimited bandwidth. A WDM-PON, however, has a cost problem that WDM-PON is used commercially. To solve this trouble, it is surveyed that a Sub-Carrier Multiplexing (SCM) used in a WDM-PON increases the number of subscribers. The performance of WDM/SCM-PON varies with various noises. The several FEC Codes can reduce the effects of noise and improve the performance of the system. Thus, Choosing a suitable FEC code is important work. This paper describes that a Reed-Solomon (RS) code is the most suitable code for WDM/SCM-PON at the object of 100 Mbps and $10^{-9}$ BER

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.237-239
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• 2005

In this paper PLC Power Circuit with Hot-Swap Function is proposed for stable power supplies. The power modules of the proposed devices are implemented by CRM flyback converter using new synchronous rectifier circuit for high efficiency. By a variable switching frequency controller, this converter is operated with a reduced turn-on switching loss. Also, the load current in these power modules are shared by auto master / slave method using Outer loop. The proposed devices are analyzed in detail and optimized for high performance. Experimental results for a 100W power module at the variable switching frequency of 30$^{\sim}$70kHz were obtained to show the performance of the proposed device.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.285-285
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• 2010

본 논문에서는 전세계가 스마트그리드 전력망을 구축하고 있는 시점에서 자동화와 정보화 사회로 빠르게 진행되면서 에너지의 원동력인 전력사용량이 증가됨에 따라 전기사고에 의한 정전 건수도 지속적으로 증가 되고 있는 실정으로 이에 대한 원인 규명과 사고 방지대책이 요구되고 있다. 잠시라도 전기 없이는 모든 산업현장은 물론 모든 행정 까지도 마비되는 중요한 전력공급은 순간 정전까지도 사전에 예방할 수 있는 시스템이 필요 불가결하다. 따라서, 전력 공급망의 공급원인 발전기에서의 차단기나 AVR 등의 제어시스템에서의 사고원인을 분석하고 이에 대한 예방대책을 제시하여 고품질의 전력을 공급할 수 있도록 하는데 있다.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.61-64
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• 2006

Recently the development of small hydropower generation with using water pipes is revitalized by the water works facilities. However, when the tubine generator is in case of emergency stop by the internal and external accidents, it causes water hammer in water pipes and suspension of water supply. To prevent these problems of small hydropower generator, we has analyzed water supply patterns, installation position and water pipe systems.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.118.1-118
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• 2001

In this paper, we suggest a new distribution model for a single phase transformer which is different from the existing model which was modeled for only primary parts, but new distribution model is modeled for primary and secondary parts. Using this model, we simulate various faults of the transformer to know how the transfer function vary from the normal one, i.e., the trend of the variation of transfer function. As an another approach, we measure the voltage and current of a three phase transformer while various faults are made at the transformer. From the simulation of the model and experiment, we fine some trends of the variation of transfer function.

• Spatial Information Research
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• v.20 no.1
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• pp.1-7
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• 2012

Hiking on the mountain is one of the most popular recreations for modern people, but many people have trouble because they select a wrong hiking trails with their own ability and this w ill be just a danger accident. It was suggested that slope analysis of hiking trails using GIS for solving this problem, and the proposed method is faster and easier than the other method. Also the slope of many hiking trails which have same destination was classified by analysing and comparing, then citizen can choose right hiking trails with their own ability.

• Communications of Mathematical Education
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• v.27 no.4
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• pp.381-389
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• 2013

In the natural science or engineering science, a calculus is an obligatory subject. So there are many classes in the university every year. Commonly professors manage the course individually. Many classes in a row individually got into trouble about lecture, test and assessment and so on. To solve the above problems, alternatively we introduced the concept of joint control. We used the joint syllabus, test and assessment. In this paper, we found the necessities and effects of joint control in a calculus.