• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.12B
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• pp.1013-1021
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• 2004

Recently, there have been the rapid increasing needs to integrate high-speed communications and digital TV in home network. To realize the integration of those services, the MIC formulated the broadband convergence network (BcN) plan as one of the new growth engines. The BcN will be implemented by FTTH solutions and these solutions are designed to support digital home network. To develop and promote the BcN, we need to find the bandwidth requirements for home network. This paper will examine the bandwidth requirements in detail to accommodate data traffics for high-speed communications and TV at building intra network and home intra network.

• Electronics and Telecommunications Trends
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• v.19 no.5 s.89
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• pp.114-124
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• 2004

유선 네트워크, 무선 이동통신 네트워크, 인터넷 등을 통합하는 유무선 통합 네트워크(BcN)에서는 VoIP기술을 사용하게 될 것이다. TTA 표준으로 2004년 7월에 제정된 VoIP 계층형 광대역 고품질 음성 코덱은 핵심계층에 G.711, G.723.1, G.729를 사용하므로 10종의 PT 를 설정하여 코덱을 협상한다. 이로 인하여 자기자신의 코덱 이외에도 G.711, G.723.1, G.729 등과 상호 호환이 되는 장점을 갖는다. 본 고는신규로 제정된 VoIP 계층형 광대역 고품질 음성 코덱을 네트워크에서 사용할 수 있도록 호 처리에 대한표준화를 추진하여야 하는데 이를 위한 표준 기술을 설명하고, 코덱과 호처리 관계 및 표준화 기술을 근거로 한 코덱 협상 처리 기술을 설명한다. 코덱 협상 처리 기술로서 PSTN/MSC 연동 코덱 협상 방안과All IP 코덱 협상 방안으로 구분하였다. All IP 코덱 협상 방안에서는 발신, 착신, MGC, 착신서버에서 호환성을 위한 호 처리 기능을 제공한다. 본 고의 호 처리 기술을 적용하면, VoIP 계층형 광대역 고품질 음성코덱은 기존 네트워크 장치 기능을 수정하지 않고 사용할 수 있다.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.5
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• pp.937-942
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• 2018

This paper maximizes the research on broadband characteristics by using air layer instead of using microstrip structure of radiation part with U-shaped slot patched inside and microstrip antenna in order to make the microstrip antenna to have broadband characteristics. Experimental results show that the VSWR is 1.4 or less than the mobile communication frequency band(820~950MHz) and the gain of the antenna is 8.2dBd. This means that the antenna can be miniaturized, and it can be used in the wireless communication fields, and the mobile communication fields for other frequency bands in the future.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.873-876
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• 2005

This paper presents a new current transient test technique for wideband CMOS Op Amps. This technique monitors the transient power supply current and output responses of the CMOS Op Amp to automatically differentiate faulty and fault-free op amps. The wideband op amp is designed using 0.25${\mu}$m CMOS technology. We present detailed simulation results for a wideband op amp. We show that catastrophic faults in op amps can be detected and analyzed by monitoring power supply currents and output responses. This technique is inexpensive and simple.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11B
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• pp.1620-1627
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• 2001

In this paper, a broadband microstrip antenna for PCS and IMT-2000 service is designed. To obtain the broadband characteristics of an antenna, we utilized the multi-layered structure composed of two foam material layers, parasitic element and aperture coupled feeding network. The broadband characteristic is obtained by changing the size of parasitic element and the height of foam materials. In addition to that, the usage of metal layer at the distance of λ/4 from feed-line, back radiation is reduced. The bandwidth of a single element for VSWR less than 1.3 is about 550MHz. The bandwidth of a designed 1$\times$4 array antenna for VSWR less than 1.3 is about 460MHz. The gain of a designed array antenna is about 11.15∼12.15dBi and the front-to-back ratio is about 30dB.

• Journal of Advanced Navigation Technology
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• v.8 no.2
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• pp.91-97
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• 2004

This paper presents the development of InGaAsP multiple quantum well asymmetric Fabry-Perot modulators(AFPM), which have a vertical structure and high performance and describes measurements of devices operating at 10GHz for next generation broadband wireless communication applications such as picocell systems. Advantages of the AFPM include low drive voltage, which is less than -2V, and -3dB coupling loss, good flatness of the frequency response and simple fiber alignment. A simple link demonstration has been introduced, resulting in 92dB/Hz spurious free dynamic range and 40dB inter-modulation distortion. This modulator could be use for broadband radio over fiber systems such as picocell and multiple RF links.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.2
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• pp.227-232
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• 2021

In this paper, the narrow-band characteristic, which is the disadvantage of the existing the PD sensor, was improved by transforming the sensor shape into a trapezoidal shape to improve the characteristics of the dipole-shaped conventional PD(Patial Discharge) sensor. In addition, by applying a cavity structure, which is a structure that can fundamentally block the electromagnetic wave signal from the outside as it is used for an external sensor, it is a partial discharge sensor that takes advantage of the structural advantages of low cost and convenience of installation. As a result of the experiment, it was shown that there is a broadband characteristic of about 70.5%(1.59~3.32GHz) at the center frequency of 2.45GHz, and the broadband characteristic was confirmed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.49-50
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• 2014

In this paper, a wideband loop antenna for UWB applications is studied. The proposed wideband loop antenna consists of a circular loop and circular sectors. Circular sectors with a ultra-wideband characteristic are used to connect the circular loop and the center feed points. Optimal design parameters are obtained by analyzing the effects of the gap between the circular sectors and the radius of the circular loop on the input reflection coefficient and gain characteristics. The optimized wideband loop antenna is fabricated on an FR4 substrate with a dimension of $41mm{\times}41mm$. Experimental results show that the antenna has a desired UWB characteristic with a frequency band of 3.1-11.0 GHz for a VSWR < 2.25.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.1234-1236
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• 2023

광대역(Wideband) 통신은 신호 대역폭이 채널의 상관 대역폭(Coherence Bandwidth)를 크게 초과하는 시스템을 나타낸다. 이때, 큰 대역폭을 갖을수록 반송 주파수대역과 사용대역의 최대 및 최소 주파수 간 차이가 커지며, 통신 시스템이 겪는 채널의 주파수 선택적 페이딩 또한 커지게 된다. 수중에서 광대역 통신을 성능을 확인하기 위한 실험을 수행하였다. 실험환경으로는 송·수신기 간 수평 이격거리는 약 10m, 수직 이격거리는 약 190m로 설정하였다. 광대역 신호의 성능을 확인하기 위하여 14kHz와 30kHz의 주파수 대역과 협대역신호와의 비교를 위해 16kHz와 4kHz 대역폭 등 파라메타를 달리하여 설정하였다. x축을 Repetition Freq.와 Repetition Time의 조합으로 설정하였으며, y축을 BER(Bit Error Rate)로 성능결과를 나타내었다.

• Korean journal of applied entomology
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• v.43 no.2
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• pp.163-168
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• 2004

Reproductive behavior of the red-striped golden stink-bug, Poecilocoris lewisi Distant, was investigated in a room at 25${\pm}$1$^{\circ}C$, 60${\pm}$5％ R.H. and the 16L：8D photo regimen. Mating of adults started on the 9th day after emergence, peaked 84.5％ on the 21st day. Mating behavior of this insect was observed as follows : approach, antennal contact, mount, abdominal approach and copulation (end-to-end position). Males were quite active and produced by rubbing their body with the cages while searching for the females. However, the females responded passively during mating. Studios were further carried to see the response of virgin pairs under controlled conditions. It was observed that 69％ of pairs succeeded in mating within one hour after the lights were switched on. Females remained unreceptive for 7 days of first mating, however, males were very much positive subject to the availability of virgin females. Although the remating frequency of female was positively correlated with fertility, but a male showed lower fertility as its frequency increased.