• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.11
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• pp.2079-2088
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• 2009

The optimal operation in distribution system is to select tie switches considering important elements(Load balance, Loss minimization, Voltage drop, Restoration index..) in distribution system. Optimal Tie Switches Selection is very important in operation of distribution system because that is closely related with efficiency and reliability. In this paper, a new algorithm considering important elements is proposed to find optimal location of tie switches. In the case study, the proposed algorithm has been testified using real distribution network of KEPCO for verifying algorithm and complex network for applying future distribution network.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.2
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• pp.83-93
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• 2013

Generally the capacities of electric power transmission tower's members are improved by increasing their stiffness nature through injection of grout or attachment of other structural stiffeners. Those are for upgrading their axial strength by fulfillment of proper materials into pipe members, increment of member dimension by addition of section, or a combination of the two. However the use of innovative and unusual procedures would be positively recommended for getting more stable state. It is that buckled members are replaced with lengthened and strengthened members. In providing the structural restoration procedures for the existing electric power transform tower whose main members have been damaged due to unequal foundation settlement, structural damage inspection works and numerical analyses for the damaged one and the restored one were done in detail at first. secondarily member-exchanging works using a newly-generated jacking system and strengthened members were achieved. This figures are to point clearly to inherent advantages attending the management of the towers.

• The Journal of the Acoustical Society of Korea
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• v.20 no.4
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• pp.22-28
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• 2001

This paper describes the implementation of a robust speaker position location system using the voice signal received by microphone array. To be robust to the reverberation which is the major factor of the performance degradation, low-frequency phase restoration algorithm which eliminates the influence of reverberations using the low-frequency information of the CPSP function is proposed. The implemented real-time system consists of a general purpose DSP (TMS320C31 of Texas instruments), analog part which contains amplifiers and filters, and digital part which is composed of the external memory and 12-bit A/D converter. In the real conference room environment, the implemented system that was constructed by the proposed algorithms showed better performance than the conventional system. The error of the TDOA estimation reduced more than 15 samples.

• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.318-320
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• 2008

우리나라의 전력계통은 수도권 전력수요 집중과 대단위 발전단지의 증가, 고장용량의 증대에 따라 고장 발생 시 정확하고 신속하게 조치하지 않을 경우 광역고장으로 파급될 우려가 있다. 전력거래소에서는 전력계통에 고장이 발생할 경우 사전에 검토된 사례를 DB화하고 이를 기반으로 EMS 상태 추정결과에 따라 현재의 계통상황에 유사한 복구절차를 자동으로 계시하여 급전원의 정확하고 신속한 고장복구를 지원하는 시스템을 개발하고자 연구를 수행하였다. 사래기반의 고장복구절차 자동제시를 위하여 계통운영방안 및 휴전검토 시의 검토결과를 자동으로 DB화 하는 프로그램을 개발하였으며 고장발생 시 계통상황을 인식하여 적합한 복구절차를 제시하여 주는 계통감시 프로그램을 개발하였다.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.125-126
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• 2006

Data storage and data communication currently pose a major problems for all parties involved with power quality and power system monitoring. The Problem aries from the tremendous amount of data involved. There is a common desire in the power industry to find new techniques for high-accuracy data compression and data storage. This paper introduces a data compression technique that is very suitable for application to power quality waveforms. The proposed technique is applied in splitting the monitored signal into two components. Those are stationary and nonstationary components. Each component is compressed and encoded.

• Proceedings of the KIEE Conference
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• summer
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• pp.446-448
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• 2004

This paper presents an application of parallel hybrid Genetic Algorithm-Tabu Search (GA-TS) algorithm to search an optimal solution of a service restoration in distribution system. In parallel hybrid GA-TS, after GA operations, strings which are not emerged in the past population are selected in the reproduction procedure. After reproduction operation, if there are many strings which are in the past population, we add new random strings into the population. If there's no improvement for the predetermined iteration, local search procedure is executed by f for the strings with high fitness function value. To show the usefulness of the proposed method, developed algorithm has been tested and compared on a practical distribution system in Korea.

• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.6
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• pp.698-703
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• 2003

This paper presents analog secure communication system about safe speech transmission using chaotic signals. We applied various conditions that happen in actuality communication environment modifying chaotic synchronization and chaotic communication schemes and analyzed restoration performance of speech signal to computer simulation. In transmitter, we made the chaotic masking signal which is added voice signal to chaotic signal using PC(Pecora ＆ Carroll) and SFB(self-feedback) control techniques and transmitted encryption signal to noisy communication channel And in order to calculate the degree of restoration performance, we proposed the definition of analog average power of recovered error signals in receiver chaotic system. The simulation results show that feedback control techniques can certify that restoration performance is superior to quantitative data than PC method about masking degree, susceptibility of parameters and channel noise. We experimentally computed the table of relation of parameter fluxion to restoration error rate which is applied the encryption key values to the chaotic secure communication.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.6
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• pp.58-64
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• 2009

Digital radiography (DR) images are corrupted by the additive noise, and also distorted by system impulse response. These unwanted phenomena are obstacles to obtain the desired image. To recover the original image, we applied multiscale Wiener filters in wavelet domain for DR images. The multiscale Wiener filter is first proposed by Chen for the restoration of fractal signals which are distorted by the system impulse response and additive noise. In this paper, we extended the multiscale Wiener filter to the two dimensional data. To compare the performance of ours with others, some simulations are given for a couple of wavelet filters with different wavelet levels, system impulse reponses and various noise power. When the addive noise powers are between 20-32 dB, the signal to noise ratio(SNR) of the proposed system is 0.5-2.0 dB better than that of the traditional Wiener filter method.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.1
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• pp.47-52
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• 2016

Fault location identification in the transmission line is an essential part of quick service restoration for maintaining a stable in power system. The application of digital schemes to protection IEDs has led to the development of digital fault locators. Normally, the impedance measurement had been used to for the location detection of transmission line faults. It is well known that the most accurate fault location scheme uses two-ended measurements. This paper deals with the complete design of a fault locator using GPS time-synchronized phasor for transmission line fault detection. The fault location algorithm uses the transmitted relaying signals from the two-ended terminal. The fault locator hardware consists of a Main Processor Unit, Analog Digital Processor Unit, Signal Interface Unit, and Power module. In this paper, sample real-time test cases using COMTRADE format of Omicron apparatus are included. We can see that the implemented fault locator identified all the test faults.

• International Journal of Costume and Fashion
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• v.8 no.1
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• pp.1-17
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• 2008

This research analyzes the patterns in modernization of costume that reflects the attitude of accepting the Western culture and the differences in perception, during modernization period (1850-early 1910) in Japan. The Japanese attitude toward the Western costume can be roughly classified into three periods: impetuous acceptance in the early Restoration of Imperial Regime(1867-1883), aggressive acceptance in Rokumeikan period(1883-1887), and the coexistence of traditional and modern costumes after Meiji 20(1887-1910). A Western costume symbolizes wealth and power until Rokumeikan period, however, as it becomes more common, it is considered as an ordinary dress rather than a ceremonial dress. The exact opposite phenomenon occurs to traditional costume. Although Japanese modernization is initially forced by western ideology of power, positive reactions to western culture and changes in perception toward China leads to more active importation of western culture. This reflects the governmental effort such as the Foreigners Employment Policy in the early Meiji period, and the public also became receptive toward change. However, acceptance of the Western culture is only limited to academic and technological areas, while the traditional Japanese ethos(the Emperor system, Shintoism, patriarchism) is obstinately protected. Therefore, it can be inferred that such extreme polarization of modernization and traditional inheritance enabled both perspectives to retain their own characteristics.