• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.334-335
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• 2003

현재 기지국과 중계기 사이의 광선로에 사용되고 있는 1310 nm와 1550 nm 파장이외에 OADM (optical add-drop multiplexer)을 사용하여 새로운 2개 파장을 광선로에 추가로 연결함으로써 광선로 임차사용의 효율을 증대시키는 4파장 광중계기의 구현시 drop신호는 삽입손실 ­3 dB 이하의 저손실특성이 요구되며 isolation 신호는 통상 ­40 dB 이상의 고품질이 요구된다. 그러나 이와같은 성능의 광모듈을 실제로 구현하기 어렵다. 따라서 많은 광결합 부품의 조합을 통해서도 drop또는 isolation 특성은 4파장 광중계기를 실용화하기 어려울 만큼 저하된다. (중략)

• 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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.4
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• pp.744-751
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• 2006

Even many kinds of Internet-based services have been generated due to the great development of the Internet. PSTN still exists in the center of the national infrastructure network and the transit exchanges will be maintained the core roles in PSTN for many years in the future. These transit exchanges often suffer from unexpected overload situation because they have to process Intelligent Network calls and mobile calls additionally as well as POTS (Plain Old Telephone Service). In this paper, we suggest an efficient overload control algorithm for the distributed transit switching system under the various types of call services. We also show that this algorithm can be implemented easily cooperating with the network management control functions. The simulation technique is used to show that the proposed algorithm effectively controls calls and maintains safely the call processor's load under the various kinds of overload situations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.8B
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• pp.1341-1347
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• 2000

For the DRT satellite transponder system, BER and total SNR to be required in the earth terminal are evaluated under the condition of HPA nonlinearity in the FBJ(full-band jamming) or PBJ(partial-band jamming) of uplink and downlink. In case that the satellite Inter bandwidth( Ws) is same to the earth terminal bandwidth($W_r$),in conditions of uplink JSR 10[dB], downlink JSR 10[dB] and processing gain 30[dB], linear transponder system shows that uplink SNR needs to be 14.2[dB] to achieve the total SNR 10[dB] requirement in downlink SNR 14[dB]. However, Nonlinear transponder system with OBO(output backoff) 2[dB] requires 20.1 [dB] uplink SNR. From the above results, the nonlinearity of HPA in the satellite transponder causes the degradation of BER performance so that it is of interest to consider the power increase.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.1
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• pp.183-188
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• 2008

Satellite DMB(Digital Multimedia Broadcasting) uses the Cap Filler(GF) that provides a service to the wave shade area of the satellite signal that is a non-line of sight area. The GF is the repeater and the Satellite DMB Systems certainly must construct the GF Network toguarantee the movement reception of the terminal. As the coverage of the GF is formed the Cell or Sector, when the multiple GF is established to be contiguous, the problem of the interference will be able to occur. This paper describes the Satellite DMB system and the GF, and it investigate the design fundamentals plan of the GF Network that it will be able to reduce this problem. As a result, in case of the distance that GF and terminal unit is above 4.6Km, service is not provided because of quality degradation according to mutual interference.

• 한국정보통신설비학회:학술대회논문집
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• 2002.08a
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• pp.31-34
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• 2002

본 논문은 Ku-band(12.4-18 GHz) 위성통신 시스템 및 이동통신 중계기용 송수신부에 사용되는 고안정도 전압제어 유전체 공진기(Voltage Controlled Dieletric Resonator Oscillator)의 설계 및 제작에 대해 논하였다. 유전체 공진기(Dielectric Resonator)의 등가회로 모델을 이용하여 유전체 공진 발진기(Dielectric Resonator Oscillator)를 설계 알고리즘화 하였다. 유전체 공진 발진기와 바렉터 다이오드를 이용하여 13.4 GHz의 전압 제어 유전체 공진 발진기를 제작하였다. 이때의 출력 전력은 +12dBm이고 위상잡음은 offset 주파수 100kHz에서 -105 dBc/Hz로 측정되었다.

• Electronics and Telecommunications Trends
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• v.8 no.3
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• pp.21-32
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• 1993

SMX/CMP는 통신망기술연구실에서 개발한 대용량 stand-alone 신호중계교환기 SMX-1을 이용하여 지능망 또는 이동통신망의 노드에 CCS No.7 접속이 가능하도록 설계된 CCS No.7 프로토콜 처리장치이다. 기존의 SMX/CMP는 2대의 대형 랙으로 구성되었으며, CCS No.7 프로토콜 처리 장치로서는 너무 크기 때문에 소형으로 되어야 한다는 요구가 있었다. 상호연결시스팀인 HSCU-8채널의 설계와 물리적인 재구성으로 SMX/CMP을 소형화 하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.10
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• pp.1129-1136
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• 2008

In this paper, a dual polarized broadband antenna fed by L-shaped strip for the Korea PCS band and W-CDMA band is presented. To analyze the characteristics of the designed antenna, we used commercial simulation tool(HFSS). The designed antenna was fabricated and measured using HP8753D vector network analyzer. The measured impedance bandwidth(VSWR<1.5) is 560 MHz and the measured average gain is 6.56 dBi. The measured isolation characteristic between two ports is -14 dB(min.) $\sim$ -40 dB(max.). These results are proper for the mobile communication application and repeater antenna.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.4
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• pp.1-7
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• 1999

The demands for the various type of directional coupler, which is for the sampling of the signal levels in mobile communication baseband or transceiver systems, are growing. The proposed dual directional coupler, which has three parallel coupled transmission lines, can provide the dual coupling and good isolation characteristics between the coupling ports. In this paper, the novel analysis method and the design equation of even and odd mode for the dual directional coupler, which is employing the asymmetrically coupled transmission lines, are proposed. Using the proposed method, the dual directional coupler for PCS system has been designed and fabricated. We obtained the desired coupling value and the high directivity of 40dB. Measured results show the validity of this design method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.406-409
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• 2003

In this paper, a 4-wavelength optical transceiver system is designed and implemented by using TFF (thin film filter) type OADMs (optical add-drop multiplexers). In this new system, the wavelengths of 1510 nm and 1530 nm are used for uploa and download signals, respectively, as well as the wavelengths of 1550 nm and 1310 nm which have been utilized in a 2-wavelength optical transceiver systems. The 4-wavelength optical module show pass characteristics of -1.6 dBm, -1.7 dBm, -5.6 dBm, -5.8dBm for 1510nm, 1530 nm, 1550 nm, 1570 nm, respectively, with 1.2 dBm of input laser power. The isolation for characteristics of the optical module for all the wavelengths are less than -40dB, which is very acceptable for filed requirements.