• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.12
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• pp.83-93
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• 2003

Differentiated service networks, based on bandwidth broker, perform the control and management of QoS provisioning for the QoS guaranteed services, However, the centralized bandwidth broker model has a scalability problem since it has centralized resource management for the admission control function of all call attempts, Therefore, in this paper, we proposea novel adaptive admission control mechanism according to the attempted call status for enhancing the scalability under the centralized bandwidth broker model in IP differentiated service networks, The proposed mechanism decouples the function of admission control from the bandwidth broker, So, the ingress edge node performs the admission control and the bandwidth broker performs the resource management and QoS provisioning, We also introduce an edge-to-edge path concepts and the ingress edge node performs the admission control under the allocated bandwidth to eachpath. The allocated bandwidth per path adaptively varies according to the status of the attempted calls, This mechanism can significantly reduce the number of communication message between the bandwidth broker and each edge node in the network and increase the bandwidth utilization via adaptable resource allocation, In this paper we study the adaptive admission control operation and show the efficient and extensive improvement through the performance evaluation.

• 기계와재료
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• v.22 no.2
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• pp.82-91
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• 2010

본 연구에서는 전력설비의 절연성능을 주간에도 육안으로 확인 할 수 있도록 태양광에서 지구에 도달하지 못하는 UVC 파장대역을 선택적으로 투과한 코로나 영상과 방전 횟수를 보여주는 시스템을 개발하였다. 선택적인 파장대역을 투과하기 위해 광학계를 개발하였고 광증폭기를 거쳐 나오는 코로나 방전 영상과 가시광 영상을 동시에 확인할 수 있는 영상합성 및 제어기를 개발하여 휴대하기 편리한 코로나 방전 영상시스템을 구축하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.4
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• pp.623-629
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• 2003

This study is about the development of a system related to the CATV network. It intends to develop an automatically centralized Headend system and a distributive system to remove the ineffectiveness of the established manual system. To achieve this goal, we took a pan of bandwidth, which is not used for the transmission of video signals in the established frequency bandwidth, and used it for the transmission and receiver of controlling signals. By this way we could design a system of transmission and receiver and a automatic distributive system. We developed an information management system for the 9600bps CATV using RS-232 of forward/backward communication and backward communication.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.68-70
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• 2013

Wireless communications based train control system which is operated with a dedicated frequency band is used only on the fixed path. Because of that, the problem arises in the area of efficiency. In this paper, a network access management technique is proposed to make the railway dedicated frequency band accessible by a normal mobile communication users efficiently and safely.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.1
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• pp.73-77
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• 2012

In this article, we designed a wide bandpass filter in order to apply microwave reflectometry for KSTAR. The proposed wide bandpass filter consists of a metamaterial structure which is to get a wide band, a lower insertion loss, and a high skirt. This is applied to VCO's output to enhance the linearity. A pass band is 18-28 GHz and the out of pass band is stopped over 20 dB. To confirm of the metamaterial, we suggest a dispersion diagram. The proposed filter in lower band and upper band of pass band is respectively a left handed and right handed characteristics. A group delay is below 0.5 ns.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.6
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• pp.632-637
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• 2000

In this paper, to control with light dimming levels of the fluorescent lamps, we have used the power line instead of the signal line to transmit the control signals. To reduce the BER(Bit Error Rate) on the power line communication with the serious noise interferences. We have adapted the FSK(Frequency Shift Keying) modulation and demodulation technique. Since the electronic ballast produced the EMI(ElctroMagnetic Interference) noise in some frequency bands, we have reduced the EMI levels in the band below -50dB. By varying the switching frequency of the ballast for the FL032/T8 from 18kHz to 25kHz, it is possible that the dimming levels are controled with the range of 5∼100%

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.10C
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• pp.1433-1443
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• 2004

The power line modem proposed in this paper transmits the remote control signal using CSK(Code Shift Keying) and DS/SS method. The CSK technique provides the increased capacity of transmission and robustness towards noise. Besides, the DS/SS technique provides protection against narrow-band Gaussian interference and multi-path interference. The modem supports full-duplex communication using FDD(Frequency Division Duplex) and the modem structure for forward link is same with that for reverse link. To switch each sub-controlled unit smoothly, 4/$\pi$-DQPSK is adopted for noncoherent demodulation. The PN code for spreading spectrum seues to divide each group which consists of sub-controlled units and Walsh code is used for the M-ary CSK technique. Each block is designed and verified with TMS320C5402 DSP. We show the superiority of the proposed method by analyzing numerically the system performance for the factors of the DS/SS and CSK method ullder additive white Gaussian noise and PBI.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.11
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• pp.1047-1054
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• 2013

In this paper, we propose a dual-mode mixer to have multi-band radar signal receiver to be compact. The proposed mixer using a anti-parallel diode is operated as a fundamental mixer or sub-harmonic mixer with respect to a control voltage. A fundamental mixer with a control voltage show a conversion loss of -10 dB, 1dB compression point of 2 dBm at X-band. On the other hand, it is performed as a sub-harmonic mixer with a conversion loss of -10 dB, 1 dB compression point of 2 dBm at K-band.

• 전자공학회논문지 IE
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• v.45 no.3
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• pp.50-55
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• 2008

In CDMA system, the number of mobile stations which can be served simultaneously in a base station is limited by the amount of total interference received. Considering the facts, the call admission control method using the effective bandwidth concept is employed in this paper. The bandwidth for a new call and a handoff call is allocated by considering the number of mobile station being served and dynamically assigned by taking account of the blocking rate of new calls and the dropping rate of handoff calls. Also, there is reserved resource for handoff call. We analyze the performance of system according to reserved resource by a simulation study. The more a resource reserved, the less it is the dropping rate of handoff.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1996.06a
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• pp.213-216
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• 1996

HDTV는 DTV에 비해 공간해상도가 4∼6배 이상됨에 따라 처리할 샘플수가 증가하게 된다. 따라서 기존의 DTV급으로 개발된 칩세트나 코덱을 그대로 HDTV 코덱 개발에 적용하기가 어렵게 된다. 따라서 HDTV의 높은 샘플링 주파수 때문에 HDTV 코덱은 화면분할 방식과 같은 새로운 코덱 구조를 가지게 되며, 그 분할된 각각은 기존의 DTV급 코덱으로 처리할 수 있게 된다. 이 때 각 대역마다 발생되는 부호화된 비트수가 다르기 때문에 일정한 전송율로 채널을 통하여 전송되기 위해서 버퍼 및 율제어 방식에 필요하게 된다. 본 논문에서는 각 대역별 영상의 특성과 버퍼 상황에 따라 적응적으로 율제어를 수행함으로써 화질의 균일성을 도모하고 부호화 효율을 증가시킬 수 있는 새로운 율제어 방식을 제안하였다. 또한 장면 전환이 발생했을 때에도 적응적으로 율제어를 수행할 수 있는 장면전환 검출 및 이를 이용한 적응적 율제어방식을 제안하였다.