• 한국통신학회논문지
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• 제33권5A호
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• pp.571-575
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• 2008

Orthogonal Frequency Division Multiplexing(OFDM) is one of the most promising techniques for 4th generation communication systems. One of the main disadvantages of OFDM is the Peak to Average Power Ratio(PAPR). In this paper, a recoverable peak cancellation(RPC) technique that recovers the cancelled part for the peak-cancelled OFDM signal is introduced. Using the RPC technique, the bit error rate(BER) performance can be greatly improved and the efficiency of the PAPR reduction is nearly that of the clipping method, at a cost of slightly reducing the transmission data rate.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2011년도 추계학술대회
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• pp.769-772
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• 2011

본 연구는 연마와 분진을 한꺼번에 해결하고자 로봇형 진공식 표면연마 머신(Robotic Vacuum Sweeping Machine)을 개발을 통하여 금속표면의 연마작업을 수행할 때 금속표면으로부터 탈피되는 각 종이물질과 연마휠의 회전으로 발생되는 분진을 진공방식으로 집진하게 되고, 항상 작업자가 머신의 이동방향을 주시해야하는 불편함을 센서(카메라, 레이저스캐너 등)를 부착하여 작업환경인식과 작업진행시 발생할 수 있는 돌발적 위험상황에 대처하기 위한 장애물 판단이 가능한 구조를 가진 진공식 표면 연마기를 소개하도록 한다.

• 한국통신학회논문지
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• 제41권1호
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• pp.77-79
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• 2016

본 논문에서는 디지털 방송시스템의 전송방식에서 널리 사용 되고 있는 계층 변조 (Hierarchical Modulation)를 고려한다. 계층 변조기법은 다수의 독립적인 데이터 스트림의 송신 신호 전력을 조절하여 변조 심볼로 매핑하기 때문에 종래의 M-QAM에서 사용하는 정규화 인수 (Normalization Factor)를 사용할 수 없다. 본 논문에서는 3-level 계층 64QAM 기법의 정확한 정규화 인수를 구하기 위한 방법과 과정을 유도하여 제시한다.

• 대한전기학회논문지:전력기술부문A
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• 제48권8호
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• pp.917-923
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• 1999

This paper proposes an efficient method of hydro-thermal scheduling in coordination with head variation and hydraulically coupled plants using Evolutionary Programing(EP). Based on the EP technique, the proposed algorithm is capable of determining the global optimal solutions. The constraints such a power balance condition, water available condition and transmission losses are embedded and satisfied throughout the proposed EP approach. The effectiveness of the proposed approach is demonstrated on the test systems and compared to those of other method. The results show that the new approach obtains a more highly optimal solutions than the conventional other methods such as newton-raphson method, Dynamic Programming(DP), LU factorization.

• 대한전기학회논문지:전력기술부문A
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• 제53권8호
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• pp.438-445
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• 2004

This paper presents a new numerical spectral domain algorithm devoted to blocking unsuccessful automatic reclosing onto permanent faults and fault distance calculation. Arc voltage amplitude and fault distance are calculated from the fundamental and third harmonics of the terminal voltages and currents phasors. From the calculated arc voltage amplitude it can be concluded if the fault is transient arcing fault or permanent arcless fault. If the fault is permanent automatic reclosure should be blocked. The algorithm can be applied for adaptive autoreclosure, distance protection, and fault location. The results of algorithm testing through computer simulation and real field record are given.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.808-810
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• 1996

In this paper, neural network, which has learning capability, is used for fault type classification and fault section estimation for high speed relaying. The potential of the neural network approach is demonstrated by simulation using ATP. The instantaneous values of voltages and currents are used the inputs of neural networks. This approach determines the fault section directly. In this paper, back-propagation network(BPN) is used for fault type classification and fault section estimation and can use for high speed relaying because it determines fault section within a few msec.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기물성,응용부문
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• pp.26-28
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• 2004

The primary role of ZnO arresters is to protect transmission and distribution equipments against lightning surges. The extremely nonlinear V-I characteristics of the ZnO arrester obviates the need for isolation gaps and consequently it is continuously connected to line voltage. For this reason, ZnO arresters are degraded with time in actual power systems. In this work, the characteristics of the luminous events caused between the ZnO block and electrodes according to the electrode area were investigated. As a result, the luminous events were effected by electrode area and the longer electrode areas were increased, the more luminous events were decreased. Also the reduction of luminous events was fumed up to the degraded ZnO arrester block.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.103-105
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• 1996

This paper describes real time dynamic tests on the digital distance relay using new digital test system including RTDS(Real Time Digital Simulator) in KEPRI. The RTDS is developed by the Manitoba HVDC Research Centre and consists of specialized hardware and software which allows transients simulation of electrical power systems in real time. From high impedance fault test, it is known that the characteristics of distance reach is influenced by load flow. A detailed discussion of relay test using the RTDS simulator, high impedance faults and test results are included in the paper.

• 전기학회논문지P
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• 제57권4호
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• pp.444-450
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• 2008

There are several ways to bond to building grounding systems for reducing GPR(ground potential rise) and EMI resulting from power system faults or lightning stroke to building. In order to verify effective bonding practice, the GPR and voltage of equipment due to the direct stroke to building are calculated with ATP-EMTP model for transformer, transmission line and MOV(Metal oxide varistor). The simulated model shows a satisfactory accuracy compared with experimental result for the $8/20{\mu}s$ simulated current pulse. It is observed that separate grounding can cause dangerous voltage to the building equipment and the performance of surge protective device can improve when it is installed to the protected equipment in distance as short as possible.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
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• pp.169-171
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• 2004

Available transfer capability(ATC) is an important indicator of the usable amount of transmission capacity accessible by several parties for commercial trading in power transaction activities. This paper deals with an application of optimization technique for available transfer capability(ATC) calculation and analyzes the results of ATC by considering several constraints. Sequential quadratic programming(SQP) is used to calculate the ATC problem with state-steady security constraints. The proposed method is applied to 10 machines 39 buses model systems to show its effectiveness.