• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.406-410
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• 1991

This paper presents an improved algorithm of optimal measurement system design with a reliability evaluation method for large power system. The proposed algorithm is developed to consider the dummy bus and to achieve highest accuracy of the state estimator as well with the limited Investment cost. The dummy bus in the power system is impossible to install measurement meter, while real and reactive power measurement values are exactly zero. Thus, the effect on these dummy bus measurements is considered in the proposed algorithm. On the other hand, P/C model is developed by taking advantage of the matrix sparsity. The improved program is successfully tested for KEPCO system with PSS/E lineflow calculated data package.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.625_626
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• 2009

전력선통신 기술은 전력선로 자체를 통신선로로 이용함으로서 전력회사에서 전력설비의 원격 감시 혹은 제어에 활용하기 매우 손쉬운 장점이 있다. 특히, 최근 부각되는 지구온난화에 대비한 에너지 절감 및 온실가스 감축을 위한 중요한 방편으로 인식되는 원격검침시스템을 전력선통신을 이용하여 구축할 경우, 경제적, 기술적으로 우수한 장점을 지닌다. 원격검침을 위해서는 일반적으로 기계식 전력량계를 전자식 전력량계로 교체하여야 하며, 전자식 전력량계가 인접한 전력선통신모뎀에 미치는 영향에 대해서는 연구된 바가 거의 없다. 따라서 본 논문에서는 전력량계가 미치는 잡음이나 삽입손실 등에 대한 특성을 시험 분석하고 전송특성에 어떻게 영향을 미치는 지 분석하여, 이를 바탕으로 전자식 전력량계의 규격 기준을 마련하고자 한다.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.2
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• pp.107-117
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• 1992

This paper presents an improved algorithm of optimal measurement design with a reliability evaluation method for a large power system. The proposed algorithm is developed to consider the dummy bus and to achieve highest accuracy of the state estimator as well with the limited investment cost. The dummy bus in the power system is impossible to install measurement meter, while real and reactive power measurements is considered in the proposed algorithm. On the other hand, P/C model is developed by taking advantage of the matrix sparsity. The improved program is successfully tested for KEPCO system with PSS/E lineflow calculated data package.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.462-463
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• 2006

본 논문에서는 당사에서 개발한 Digital Relay 및 Meter와 같은 IED들의 고장/이벤트 파형을 분석하는 툴인 Wave Analyzer를 소개한다. 기존 당사 파형 분석 툴들은 각기 하나의 IED에 대해서만 적용 가능하였으나 Wave Analyzer는 당사의 모든 IED에 대해 적용 가능하도록 통합형으로 개발하였다. 또한 고조파 분석, 벡터 다이어그램 등 파형 분석에 필요한 다양한 기능을 제공한다. Wave Analyzer는 다양한 기능을 가지고 있으며 모든 IED에 적용할 수 있어 당사 IED를 사용하는 사용자들에게 보다 편리함과 유용함을 제공할 것이다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.179-180
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• 2008

배전선로의 효과적인 운영을 위해 최근 들어 자동검침 데이터를 활용한 부하분석에 대한 연구가 진행되고 있다. 일반적인 부하분석 방식은 자동검침 고객의 데이터를 이용하여 대표 부하패턴을 생성하고 이를 이용하여 미 검침 고객의 부하패턴을 생성하여, 전체 배전선로의 회선 및 구간에 대한 15분/시간/일/주/월 단위의 최대부하 및 부하패턴 등을 분석하는 방법이다. 기존에는 고객을 분류하기 위해 계약종별 코드만을 사용하였으나, 같은 계약종별 코드를 갖는 고객이라 하더라도 부하패턴이 다른 경우가 많아서 부하분석의 정확도를 떨어뜨렸다. 본 연구에서는 고객의 계약종별 코드뿐 아니라 다양한 고객속성 정보와 15분 단위 자동검침 데이터를 이용하여 k-means 기법을 통해 고객을 분류하는 방식을 제안하였다.

• International Journal of Aeronautical and Space Sciences
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• v.6 no.1
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• pp.77-88
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• 2005

KOMPSAT-2 is the second Korean earth observation satellite after KOMPSAT-l: the 1 meter GSD cartographic capability and planning to launch at the end of 2005 by ROKOT launch vehicle. The dedicated AOCS operational modes are designed for KOMPSAT-2 based on KOMPSAT-l experience All of AOCS operational modes requires gyro information. To compensate this drawback, Power Safe Mode is designed and implemented. Successfully AOCS on-board software is developed and extensively verified through a nonlinear simulation process. The simulation results of Power Safe Mode and Science Fine Submode are provided to demonstrate its functionality as well as its performance.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.69-71
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• 2001

In this paper, we propose a new communication protocol for remote metering in electric power meters, also define necessary functions for it. The new protocol is based on the international metering protocol. IEC 1107, 62056, DNP 3.0. This protocol has 4-layered architecture, which has physical. data link, lower application, and upper application layers. For each layer, definitions and detailed functions are introduced. The protocol will be used for communication between the meters and the metering computer(or AMR system). KEPCO (Korea Electric Power Corporation) plans to adopt this protocol as a part of a new metering standard for electric power meters.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2139-2141
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• 1998

This study was carried out about the manufacture of test equipment for traction Motor Driving. The power converter is driven by two converter serially and keep a high power factor of power source. This system is haven all the characteristic of voltage source converter by having a processing ability of regenerating power. The traction motor is controlled by IGBT inverter. The test equipment is composed of traction motor, torque-meter, clutch, and inertia body of tubular type.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.1
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• pp.62-65
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• 2019

Wireless power transfer systems require an algorithm to determine the presence of the target object for mitigating standby power and safety issues. Although many schemes that sense various external objects have been actively proposed for inductive power transfer systems, not many studies on capacitive power transfer systems have been conducted compared with those on inductive power transfer systems. This study proposes a target object detection algorithm by monitoring the capacitance in transmitter-side electrodes without additional pressure sensors or distance sensors. The proposed algorithm determines the presence of a target object by monitoring the change in capacitance in transmitter-side electrodes using the step pulse of the microcontroller unit. The algorithm is verified by two step processes. First, the performance in capacitance measurement is compared with that of an LCR meter. Then, the verification is conducted in a 5-W capacitive power transfer hardware. Experimental result shows that the interelectrode capacitance increases by 6 times when the target object is fully aligned. Thus, the proposed scheme can successfully detect the presence of the target object.

• Current Optics and Photonics
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• v.1 no.5
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• pp.538-543
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• 2017

Progressive addition lenses (PAL) have very wide application in the modern glasses market. The unique progressive surface can make a lens have progressive refractive power, which can meet the human eye's different needs for distance-vision and near-vision. According to the national glasses fabrication standard, the difference between actual optical power after fabrication and nominal design value should be less than 0.1D over the lens effective area. The optical power distribution of PAL is determined directly by the surface. Consequently, the surface processing accuracy requirement is proposed. Beginning from the surface expressions of progressive addition lenses, the relationship equations between the surface sag and optical power distribution are derived. They are demonstrated through tolerance analysis and test of an example progressive addition lens with addition of 2.09D (5.46D-7.55D). The example addition surface is fabricated under given accuracy by a single-point diamond ultra-precision machine. The optical power of the PAL example is tested with a focal-meter after fabrication. The optical power addition difference between test result and design nominal value is 0.09D, which is less than 0.1D. The derived relationship between the surface error and optical power is verified from the PAL example simulation and test result. It can provide theoretical tolerance analysis proof for the PAL surface fabricating process.