• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.10
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• pp.39-46
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• 1999

In this paper, we propose new hardware architecture of a fast searcher for an initial code acquisition in wideband CDMA wireless local loop systems. The proposed searcher uses double-dwell serial search algorithm and has N active correlators for the high performance code acquisition. Since the N active correlators are designed with pipelined architecture, it is possible to reduce the hardware complexity with only one energy calculation. Our architecture is designed using VHDL to meet wideband CDMA wireless local loop standard and verified under JTC wideband channels. Average code acquisition time of the proposed fast searcher which has 16 correlators is about 40 seconds in case of initial installation and 0.16 seconds when a base station is known. The verified fast searcher is synthesized with in $0.6\mu\textrm{m}$ LG library. The synthesized searcher has 15.8K rates when the number of 4he correlators is 16.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.4
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• pp.65-71
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• 1984

The design formular of optical focusing systems cannot be applied to ultrasonic B scanners, which use broadband pulses instead of continuous wave. In this paper, a calculation method is studied for analyzing the propagation of ultrasonic broadband pulse excited by ultrasonic array transducers. Using the results, seveial design parameters such as the number of transducer elements, delay time, and the focal point are determined to obtain high resolution in the ultrasonic dynamic focusing system. A dynamic focusing system with low-noise switching characteristics; which attains lateral resolution of 2-3mm all along the axial direction up to 18 cm with a 3.5 MHz linear array transducer, was implemented.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.3013-3015
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• 2005

UWB 통신기술은 초 광대역 특성 때문에 높은 전송속도와 저전력 통신이 가능하다는 이유로 Bluetooth 이후에 최근에 매우 각광을 받는 통신 응용분야이다. 따라서, 다양한 UWB 통신 기술의 적용을 위하여 UWB 신호의 특성과 변조 방법을 연구하는 것은 매우 중요하다. 본 논문에서는 UWB 통신에 사용가능한 가우시언 모노펄스의 펄스폭에 따른 BPSK 변조 방법의 성능을 비교하였다.

• Journal of Advanced Navigation Technology
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• v.10 no.3
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• pp.268-275
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• 2006

The rapid proliferation of in-home and office information applications and services is driving the need for new wireless technologies enabling wideband short range multimedia communications. Due to the growing demand for higher quality media and faster wireless connections, several IEEE standardization groups are considering very high data rate alternatives physical layer(s) for Wireless Personal Area Network (WPAN). The Ultra Wide Band (UWB) multiple access technology based on very narrow pulse transmission, is one viable candidate for these applications providing very high bit rates services, low power consumption and accurate positioning capability. In this paper we provide a methodology to evaluate the UWB system BER performance in UWB wireless fading networks with power controlled UWB devices are considered. Results can be used to analyze the performance of a given network topology and to provide useful design ideas for an UWB home sensor network.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2070-2072
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• 2004

극 초단의 임펄스를 사용하여 지중 매설물을 탐색하기 위한 지반탐사 영상 레이더를 개발하였다. 개발된 지반 탐사 레이더는 Gaussian 임펄스, 임펄스 송수신을 위한 초 광대역 소형 모노폴 안테나, 수신 신호 저장을 위한 고속 A/D로 구성된다. 탐지 깊이와 시스템의 크기를 고려하여 임펄스 발생기 및 초광대역 안테나가 설계되었다. 지중 매설물의 영상화를 위해 여러 가지 이미지 기법이 사용되었다. 발표에서는 구현된 시스템의 시제품을 소개하고, 개발된 시제품을 사용하여 가상의 모래 시험장에서 측정된 결과를 보일 것이다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.488-491
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• 2003

UWB communication applications is a recent innovation due to high transmission rate and low power emission. There, we analyzed monopulse's characteristics and simulated the performance for various UWB communication applications. we introduced Time-Hopping method and simulated for MAI removal in multi-user communication.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.6
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• pp.1402-1409
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• 2007

In this paper, we propose various types of AGC algorithms for implementing the OFDM communication systems. For the high-speed packet transmission, in this paper, we assume the OFDM system with relatively long and repeated preambles. We propose the maximum sample value counter for counting the number of maximum sample. In the maximum sample value counter, we use the buffer for the digital signal buffering. Finally, the counting value of the maximum sample value counter controls the gain control signal generator by using gain control table automatically.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.6
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• pp.553-563
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• 2010

This paper presents a tapered slot-antenna(TSA) for optimal impulse-signal transmission in ultra-wide band(UWB). The proposed TSA provides radiates in end-fire direction, which meets an impulse-radio UWB(IR-UWB) system demands(e.g., low loss, thus less error throughout the UWB band). In order to minimize the pulse distortion, we used an wideband impedance transformer and a microstrip slotline. The pulse fidelity characteristics was evaluated with finite-difference time-domain(FDTD) analysis technique and pulse fidelity correlation equation. Approximately 93.89 % pulse fidelity was obtained between the two antennas in 0.5 m range. Additionally, derived chirp Z-transform algorithm enables us to utilize the zoom-in option on the pulse signal in few nano-seconds below. Thus, it is possible to analyze the pulse signal distortion, delay or dispersion characteristics.

• Electronics and Telecommunications Trends
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• v.21 no.4 s.100
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• pp.107-117
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• 2006

위성 탑재체 제조 산업은 기초 과학이 뒷받침된 초정밀 기계 공학, 첨단 전자 기술, 극한 환경 기술 및 신소재 공학 등과 같은 첨단 산업의 집합체라 할 수 있다. 현재 미국을 비롯한 서구 선진국에서 진행중인 탑재체 기술동향을 보면, 폭발적으로 증가하는 위성수에 따라 위성 궤도가 부족하고 주파수 자원이 고갈되고 있는 상황에서 통신 위성의 효율성과 성능을 향상시킬 수 있는 신호처리 탑재(OBP) 위성과 통신기능을 포함한 다양한 기능을 가진 복합위성 개발이 진행되고 있으며 주파수 대역의 포화와 광대역 멀티미디어 서비스 제공 등을 위해 보다 높은 주파수의 준 밀리미터파 대역(Ka 대역) 위성 개발이 활발히 이루어지고 있다. 국내에서는 현재, 2008년 발사를 목표로 마이크로스위치 매트릭스(MSM)가 탑재되어 빔간 스위칭이 가능하도록 설계된 통신해양기상위성(COMS)용 통신 탑재체(SACOM) 개발이 진행중이다. 국내의 위성탑재용 RF 부품분야는 1990년부터 위성 중계기 시스템의 기본적인 설계, 조립, 종합화, 시험기술을 바탕으로 통신위성 탑재체용 초고주파 부품을 개발하여 왔으며, 2000년대에는 Ku 대역(12/14GHz) 및 Ka 대역(20/30GHz) 기술인증모델(EQM) RF 부품을 성공적으로 개발하였다. 이를 바탕으로 통신해양기상위성 통신탑재체용 Ka 대역 RF 부품이 현재 우주인증 모델(QM)의 개발이 완료되었으며 비행 모델(FM) 개발이 진행중이다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.2
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• pp.315-321
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• 2011

Since the MB-OFDM(Multi-Band Orthogonal Frequency Division Multiplexing) is an ultra wideband communication system operated on ISM(Industrial, Scientific and Medical) band, DAA(Detect-And-Avoid) is required for co-existence with the other communication service. In this paper we propose the new detection algorithm based on decision-feedback, which shows faster convergence time and less complexity than previous works. The proposed algorithm detects interference above -20dB in AWGN(Additive White Gaussian Noise) and LOS(Line-Of-Sight) channel, and close to AWGN in non-LOS channel under appropriate channel clipping.