• Communications of the Korean Mathematical Society
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• v.13 no.3
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• pp.635-642
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• 1998

When an integrated communication system is congested, we may reserve some spaces for non-realtime traffic by discarding a part of realtime traffic. That is sensible because realtime traffic is insensitive to a few losses. Several discarding schemes have been developed including Separate Queue (SQ). Under such schemes, the block loss distribution, i.e., the distribution of the number of losses within a given block which consists of successive data of a type, is important. We derive the block loss distribution of the SQ scheme and modifies the SQ scheme with a threshold.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.78-81
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• 2008

Capacitors are known as condensers. They play an important in the industrial site because of benefits such as var support, improved voltage control and power factor, increased system capacity, and reduction of system power losses. But capacitors can be seriously affected by bad power quality such as transient and impulsive overvoltage, overload, harmonics. Capacitor standards and application guides are revised or supplemented by speedy technology advancements in the manufacturing of capacitors and in the power electronics. This paper presents various illustrations and comparison for several standards of power system capacitors.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.5 no.1
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• pp.54-59
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• 1980

Adaptive version of the delta modulator that is akin to wyllabic companding for telephony is described. A digital technique is used to sense the slope of the input signal and to control the amplitude of the pulses supplied to the RC network in the feed back loop. Thus the development was stimulated by the suitability of delta modulator for low-cost integrated circuits. Analysis are made of the optimum overload characteristics, stability, SNR for improving the frequency range and these results have been esperimentally verfied.

• Journal of Applied Reliability
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• v.6 no.4
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• pp.255-274
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• 2006

Recently firms become largely changed because of rapid technological innovation and serious global competition. It induces job stress of workers and finally leads to job burnout. This study aims to find the effects of job demands and job resources on job burnout. Job demands contains role ambiguity, role conflict, role overload and job characteristics. Job resources contains job control and feedback, involvement in decision making, learning opportunity and social support. The result reveals that job demands raises job burnout and job resources decreases job burnout. And it reveals that the effects of job demands and job resources on job burnout differs slightly according to job categories.

• Journal of Information Technology Applications and Management
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• v.13 no.2
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• pp.55-65
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• 2006

Since the World-Wide Web (WWW) has become a major channel for information delivery, information overload also has become a serious problem to the Internet users. Therefore, effective information searching is critical to the success of Internet services. We present an integrated search engine for searching relevant web pages on the WWW in a certain Internet domain. It supports a local search on the web sites. The spider obtains all of the web pages from the web sites through web links. It operates autonomously without any human supervision. We developed state transition diagram to control navigation and analyze link structure of each web site. We have implemented an integrated local search engine and it shows that a higher satisfaction is obtained. From the user evaluation, we also find that higher precision is obtained.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.1062-1068
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• 2007

We are using COS to block the excess current and to protect the transformer. But the fuse of COS is melt due to the overload resulting from the excess current flows and it destroys an air severing relations to clear as strong arc happens. Such phenomenon induces an impact ambient noise and it gives the circumstance area resident or pedestrian the fear. Thus, it is necessary that we urgently need to control the ambient noise from the actual circumstances. In this study, we investigate the characteristic of an impact ambient noise associate with the melting state of the COS fuse and suggest the method to reduce the noise.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.15-16
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• 2015

According to 2014 fire statistical yearbook in the National Fire Data System, a main cause of fire is electrical fire except carelessness fire. Joint/contact badness is the one of the main cause of electrical fire. Furthermore, power relays which are used in electric panel board, motor control center and automation controller, are main element of automation system in the industry field. Overload, voltage unbalance and open-phase due to joint/contact badness of terminal make electric accidents or electrical fires. In order to prevent joint/contact badness of terminal, this paper proposes a sensing circuit of chattering, tracking, arc current, voltage unbalance and open-phase etc. Some experimental tests of the proposed apparatus confirm practicality and validity of the theoretical results.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.351-354
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• 2012

본 연구는 LED 조명제어시스템(LMS)을 이용해서 관리자가 원하는 목표전력량과 LED 조명의 구역별 중요도에 따라 Priority 를 설정 후 실시간으로 전력량을 측정해서 Overload(목표전력량 80% 이상 초과 1 단계, 90% 이상 2 단계) 상황 발생 시 자동으로 LED 조명전력을 차단 또는 디밍함으로써 정전에 대비하고 에너지절감도 가능한 알고리즘과 실증결과에 관한 연구내용을 소개한다.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.6
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• pp.411-420
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• 2021

In this paper, bidirectional LLC-LC resonant DC-DC converter with notch filters in the primary side of resonant circuits is proposed. Even if resonant capacitors are used on the primary and secondary sides, the proposed converter can operate with the high gain characteristics of the LLC resonant converter without mutual coupling of resonant capacitors, regardless of the direction of power flow. In addition, by applying notch filters, the proposed converter can operate with a wider gain control range and can cope with overload and short circuit. The analysis and operating characteristics of the proposed bidirectional LLC-LC resonant converter are investigated. A 3.3 kW prototyped bidirectional LLC-LC resonant converter connected to 750 V_DC buses is designed and tested to verify the validity and applicability of this proposed converter.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.489-492
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• 2011

SIP (Session Initiation Protocol)는 사용자간의 멀티미디어 세션의 초기화, 변경 및 종료를 위한 응용 계층의 시그널링 프로토콜이다. SIP는 실시간 멀티미디어 서비스 통신에 많이 이용되기 때문에 주로 Unreliable Transport Protocol을 사용한다. 따라서 손실된 SIP 메시지들의 신뢰성을 보장하기 위하여 재전송 메커니즘을 제공한다. 하지만 이러한 재전송 메커니즘은 SIP 프록시 서버가 과부하 상황일 경우 신뢰성보다는 오버헤드가 증가되는 문제점을 가진다. 기존의 여러 SIP 과부하 제어 방법이 제안되었지만 네트워크 혼잡이 증가함에 따라 프록시 서버의 처리율이나 호 설정 시간의 지연 문제를 효율적으로 해결하지 못한다. 본 논문에서는 SIP 시그널링 네트워크에서 프록시 서버가 과부하 상황일 경우 낮은 호 설정 지연시간과 높은 처리율을 위해 우선순위 스케줄링 기반의 과부하 제어 알고리즘을 제안한다. 그리고 기존 과부하 제어에서 사용하는 알고리즘과 제안하는 알고리즘을 비교하여 보았다. 성능 평가 결과 부하에 따른 프록시 서버의 처리율과 호 설정 시간의 지연 측면에서 기존의 과부하 제어 알고리즘보다 향상됨을 보였다.