• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.6
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• pp.910-916
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• 1999

This paper presents the effective improvement of the thermal runaway phenomenon in high power SSPA when the RF input signal is not provided. The total gate resistors are optimized by the experiments and deducing the variation of velocity and currents of thermal runaway, which is based on manufacturer's recommendation. Especially, it is solved the complex thermal runaway that related gate resistors with the gate voltage variable circuit. The result of this paper is able to apply for improving the thermal runaway in existence of high power SSPA for WLL, cellular system and PCS repeater.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.36-37
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• 2001

광통신 시스템이 널리 사용되기 시작한 이래 광섬유를 통한 원거리 전송에 따른 신호의 감쇠와 왜곡 등의 문제점이 발생하게 되고 이를 보상하기 위해 중계기(Repeater)의 사용이 요구된다. 이러한 중계기에는 광전변환, 전기신호처리 및 전광변환 등의 번거러움이 따른다. 이와 같은 번거로움 때문에 광통신 시스템 설계자들은 광전, 전광 변환 없이 바로 광신호 자체의 세기를 증폭하는 기술을 필요로 하게 되었다. 특히 최근 들어 파장분할다중(Wavelength Division Multiplexing)광 네트웍 및 광통신의 고속화가 요구됨에 따라 중계기를 광증폭기로 대치하는 추세는 더욱 가속화되고 있다. (중략)

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.165-166
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• 2006

By using a ceramic material with dielectric constant 37, the miniature waveguide ceramic bandpass filter was implemented. The proposed waveguide ceramic bandpass filte was based on the mode matching method and simulation process. For overcoming high power, We used the connector at in/output of waveguide ceramic bandpass filte. The result of power test satisfied the 30W. The product will used as a parts of repeater for wibroband.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.3
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• pp.253-262
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• 2003

In this paper, the interference cancellation system, which is used to cancel the feedback signal in the wireless communication system with the same frequency, is studied. The time varying feedback signal generated from transmitter antenna to receiver antenna reduces the performance of the receiver system. the interference cancellation system using adaptive feedback method(AF-ICS) is suggested to prevent the oscillation of the receiver system and maintain the maximum output power of the power amplifier by the reduction of time-varying feedback signal and also this paper conforms that the oscillation disappears from the output signal by cancellation of the feedback signal and the total output power is satisfied the system specification.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.1
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• pp.156-160
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• 2012

Recently WCDMA signal transmission technology by large output microwave antenna have showed reduction of human resources and operating expense. But the existing antenna brackets cost is very expensive also its structure and functions are complicated. Unit brackets, suspending some sensors, subjected to acceleration loads, often fail due to self-vibration. To prevent such failures, it is necessary to understand the fatigue failure mode and to evaluate the fatigue life using tests or analysis techniques. The objective of this study is to develop the component test specifications, which are applicable to predict fatigue life at initial product design step, for unit brackets using vibration fatigue technique. So its application is limited to installation and management. In this project, we studied about more convenient bracket for microwave antennas through improvement on the existing antenna bracket's shortcoming and could develop an improved universal antenna bracket system for simple installation and application.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.119-120
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• 2007

The operation of Interference cancellation algorithm for wireless repeater cancellation depends on either existing correlation properties between desired signal and reference signal or not At the time, due to the correlation properties at the ICS system, adaptive algorithms without considering system delay do not function properly. Thus, this system should be oscillated. In this paper, to solve these problems, we use the delayed least mean square algorithm. For the best performance of ICS, the system delays must be estimated. To efficiently estimate the delay of ICS, we use relations between bandwidth and correlation properties of the received signal.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10A
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• pp.1486-1491
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• 2000

A Multicarrier system required a lower speed paralled-type of signal processing in contrast to a fast serial processing in a single carrier CDMA system. For the analysis we evaluate MC-CDMA system performance with that of a single-carrier CDMA system and a multi-carrier CDMA system based on the various jamming conditions. Also we studied to the capacity level against the threat environment through the performance comparison in commercial CDMA system and Limiting repeater system. as a result we found that M-CDMA system has a robustness to narrowband interference and multipath environments like as a Rayleigh fading.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9B
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• pp.1511-1517
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• 2000

A new slot-coupled back-to-back microstrip array antenna is proposed for using in the IMT-2000 base station or repeater antenna. This antenna is composed of symmetrical SSAIP(Strip Slot, Air Inverted Patch) It has bidirectional radiation pattern in horizontal plane and 22.5$^{\circ}$main beam squint in vertical plane. The analysis is based on the cavity model and the design is achieved using Ensemble. Experimental results for the radiation pattern and the return loss have shown that the direction of the main beam is about 21$^{\circ}$and the impedance bandwidth is approximately 22.9% Thus the proposed antenna is able to operate over both uplink and downlink frequencies in IMT-2000.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.2016-2021
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• 2009

In this paper, a dual-band antenna aimed for a mobile communication repeater was designed and measured. The operating frequency ranges are GSM(870${\sim}$960 MHz) and WCDMA(1920${\sim}$2170 MHz) bands. Experimental and numerical studies are performed for various design variables such as slot lengths. Using two meandering slots in the ground plane, we can obtain two higher resonant frequencies significantly with broader bandwidths. The measured maximum gain of antenna is 2 dBi in the GSM band and 2.45 dBi in the WCDMA band.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.3-5
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• 2000

1.8V,4Gb DDR SDRAM설계 및 제작을 수행하였다. DRAM동작 시 발생하는 Bit Line간 CouplingNoise를 보상하기 위한 Twisted Open Bit Line 구조를 제안하였다. Low Voltage Operation으로 인한 Bit Line Sense Amplifier 의 동작 저하를 보상하기 위한 BL S/A Pre-Sensing 방식 및 Reference Bit Line Voltage Calibration 구조를 제안하였다. Chip면적 증가로 인한 동작속도 감소의 보상을 위해 Repeater Driver 구조를 Core 및 Periphery Circuit에 적용하여 동작 대비 Chip 면적의 증가를 최소화 하도록 하였다.