• The Journal of Information Systems
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• v.18 no.3
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• pp.231-249
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• 2009

Recently, plant construction industries are enjoying a favorable business climate centering around developing countries and oil producing countries rich in oil money. This paper proposes a methodology of implementing case-based reasoning(CBR) system for managing knowledge like lessons learned and various documents accumulated in performing power plant construction projects which are receiving a lot of order from foreign countries such as the Middle East, etc. Our methodology is consisted of 10 steps : user requirement gathering, information modeling, case modeling, case base design, similarity function design, user interface design, case base building, CBR module development, user interface implementation, integration test. Also, to illustrate the effectiveness of proposed methodology, the real CBR system is implemented for the plant business division of 'H' company which has international competitiveness in the field of plant construction industry. At present, the implemented CBR system is successfully utilizing as storing, sharing, and reusing knowledge which is accumulated in performing power plant construction projects in the target enterprise.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.5
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• pp.34-41
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• 2008

This paper describes the design of SP3T PIN diode switch which has a 500W high power handling capability in $20{\sim}400MHz$ frequency range. Design factors were investigated and it was confirmed by simulation that the characteristics of insertion loss, VSWR, and isolation met design goal. Also, the capability to handle 500W high power with very fast switching speed of less than $26{\mu}s$ was confirmed and insertion loss of less than 1dB, VSWR of less than 1.4:1, and isolation of higher than 60dB were obtained by experiments.

• Proceedings of the KIEE Conference
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• summer
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• pp.725-727
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• 2004

As the electrical power industry is restructured, the electrical power exchange is extended. In Cheju, demand increases about $10\%$ every year To cope with future demand, HVDC System usage should grow, This paper proposes optimal transfer capability of Haenam-Cheju fm System through cost optimization that considers generating cost, receiving cost and outage cost.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.7
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• pp.397-404
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• 2004

This paper describes a study of transient characteristics in 765kV untransposed transmission lines. As the 765(kV) system can carry bulk power, some severe fault on the system nay cause large system disturbance. The large shunt capacitance and small resistance of 765kv transmission line make various difficulties for its protection. These problems including current difference between sending and receiving terminals on normal power flow, low order harmonic current component in fault current and current transformer saturation due to the long DC time constant of the circuit etc. must be investigated and solved. The analysis of transient characteristics at sending terminal has been carried out for the single phase to ground fault and 3-phase short fault, etc. The load current, charging current in normal condition and line flows, fault current, THD(Total Harmonic Distortion) of harmonics, time constants have been analysed for the 765kV untransposed transmission line systems.

• Journal of Power System Engineering
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• v.10 no.2
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• pp.93-98
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• 2006

Metal matrix composites(MMCs) reinforced with ceramic particulates are receiving increasing attention because their high specific strength, low coefficient of thermal expansion and excellent wear resistance. Especially, Al-based composites(AMCs) have been widely applied for the aerospace and automotive industries. Such composites are mainly fabricated by the cast, powder metallurgy and infiltration process. In this study, SiC particulate reinforced Al-based composites were fabricated by thermal spray process and their wear behavior were investigated. Composites with different spray parameter were fabricated by using flame spray apparatus. Microstructure and wear behavior of the composites were observed by scanning electron microscope(SEM) and electron probe micro-analysis(EPMA).

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.9
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• pp.67-75
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• 1994

In this paper, we manufactured the continuum receiver system for observing the continuum waves emitted from the continuum sources with using the 14m radio-telescope. The receiving system measures the total power of the continuum sources and consists of DC-amplifier, beam-chopper system. Phase-Locked Loop(PLL) circuit, blanking circuit and its period selection circuit, V/F converter, and counter part which are capable of interfacing with the computer which is used for a data acquisition and making the radio-telescope track the source. We compared the obsevation results which use the existing DVM method with the observation results which use the continuum receiver to measure the total power of the sources. Moreover, by method of beam switching observation which uses newly installed beam chopper system. We can significantly improve the observational efficiency more than the existing position switching observation method.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1279-1280
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• 2015

본 논문은 저전력 센서를 위한 무선 전력 수신 시스템을 설계하여 Wake-up 회로에 응용함으로써, 유효 신호의 입사 시에만 동작되는 수신기 시스템을 제안하였다. 제안 된 시스템은 기존 여파기를 DGS(Defected Ground Structure) 형태로 설계하여 소형화에 기여하였으며 여파기는 다이오드에 의해 생성되는 고조파 신호의 제거와 DC 통과의 역할을 수행하게 된다. 설계된 Rectenna의 변활 전력을 이용하여 수신기 시스템 스위치의 온, 오프를 조절함으로써 저전력 센서 수신 시스템의 동작 여부를 평가하였다. 제안된 시스템은 신호 수신 여부에 따른 저 잡음 증폭기와 데이터 복조의 동작 여부로 성능이 평가되었으며 우수한 동작 성능을 나타내었다.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.453-453
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• 2000

This paper presented Fuzzy logic application to Electrical power system analysis for fault location estimation in distribution lines and apply the Power system theory to be fuzzy logic database. The case study referred to the Overhead distribution line of the Provincial Electricity Authority (PEA.), Thailand which mostly the distribution line of PEA. are Radial schemes. These benefits include reduced outage time, help in locating momentary faults, enhance safety to the line crews and provide notification of an outage without receiving calls from the consumer, Which these benefits also increase Reliability, Stability and Efficiency.

• Journal of Sensor Science and Technology
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• v.9 no.6
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• pp.448-454
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• 2000

This paper describes the implementation of a multi-subject, multi-channel optical telemetry system for the short range measurement of electrocardiograms (EKGs) a system which receives command signals and transmits physiological signals to the external system using LED (Light Emitting Diode) and PD (Photodiode). This system decreases the dependency of power supply voltage to the CMOS IC chips and a new enforced synchronization technique using infrared bi-directional communication has also been proposed. The telemetry IC with the size of $5.1{\times}5.1mm^2$ has the following functions: receiving of command signal, initialization of internal state of all functional blocks, decoding of subject selection signal, time division multiplexing of 4-channel modulated physiological signals, transmission of modulated signals to external system, and auto power down control.

• Korean Journal of Acupuncture
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• v.36 no.4
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• pp.241-251
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• 2019

Objectives : The purpose of this study was to examine the effects of electroacupuncture at GB14, on brain activity assessed on an electroencephalogram(EEG). Methods : (1) Thirty-four healthy participants were randomly divided into two groups, receiving either real acupuncture or non-penetrating sham acupuncture at GB14. (2) EEG measurements were conducted simultaneously before and after a 5-minute electroacupuncture stimulation, and the differences in the resulting EEG parameters were compared between the test and control groups. Results : (1) Absolute power increased significantly in the theta-wave channel of the occipital region and in the entire alpha-wave channel. (2) Relative power decreased significantly in the theta-wave channels of the frontal and occipital regions. (3) Coherence decreased significantly in the theta- and beta-wave channels of the parietal and occipital regions, and increased significantly in the alpha-wave channels of most areas. Conclusions : This study shows that electroacupuncture stimulation at GB14 activates the alpha frequency band in particular.