• 대한전자공학회논문지
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• 제21권4호
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• pp.37-42
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• 1984

전송속도가 9600bps인 고속 data modem에서 효과적인 symbol timing 회로의 구성방식이 제시되었다. Symbol timing 회로에 소요되는 계산량을 줄이기 위한 방식 및 그것이 수신기의 mean square error(MSE)에 미치는 영향이 제시되었고 timing wave의 통계적 특성에 대한 이론적인 전개가 행하여졌다. Digital Phase-looted loop(DPLL)에 의해서 timing wave의 side tone 성분을 억제할 수 있음을 보였고 computer simulation에 의해서 송신기의 symbol 주파수를 변화시켰을 경우 1차 DPLL과 2차 DPLL의 동작이 비교되었다.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.109-110
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• 2006

The performance of a digital baseband signal processing and data transmission rate depends on the modulation technique. In this paper, We implemented DSP communication system for Underwater acoustic communication using by adaptive BPSK modem technique. In order to implement adaptive modem, we suggested SNR detection block. SNR detection block has the reference SNR value that selects between window filter path and matched filter path. In this paper, suggested system is based on software interface and all Hardware(PLL, modem filter, equalizer etc) is implemented by software, exclusive of DSP, A/D, D/A converter, SDRAM and Flash memory.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
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• pp.97-100
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• 2003

The quasi-complementary turbo codes (QCTC) proposed by Kim [1] is used for a fast hybrid ARQ scheme with incremental redundancy and adaptive modulation coding in the cdma2000 1xEV-DV [2]. The QCTC provides various code rates with good performance, a very simple encoder structure, and an inherent channel interleaving. It is shown that the QCTC is a unified scheme of channel coding and channel interleaving. In this paper, we introduce the properties of QCTC and various hybrid ARQ-QCTC schemes for the system.

• 전자공학회논문지A
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• 제33A권6호
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• pp.220-229
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• 1996

We presetn sytem-level simulation methodology as well as environment setup established for CDMA digtial cellular mobile station in an effort to verify CDMA modem ASIC design. To make the system-level simulation feasible, behavioral modeling of a microcontroller was first carried out with VHDL. In addition, models written in C language were also developed to provide ASIC with realistic input data. Finally, the netlist of CDMA modem ASIC was loaded on the a hardware accelerator, which was interfaced with VHDL simulator, and ismulation was performed by excuting the actual CDMA call processing software. Simulation resutls thus obtained were confirmed by comparing them with the emulation resutls from the actual system constructed on hardware modeler. these methods were proved to be effective in both discovering in advance malfunctions when embedded in the system or design errors of ASIC and reducing simulation time by a factor of as much as 20 in case of simulation at gate-level.

• 디지털콘텐츠학회 논문지
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• 제7권2호
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• pp.109-115
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• 2006

잡음환경이 열악하고 대역폭이 부족한 HFC 망 상향채널에서 보다 나은 대칭형 멀티미디어 서비스를 제공할 수 있는 S-DMT 방식의 상향 채널 케이블모뎀을 위한 등화기를 설계하고 그에 대한 성능을 평가하였다. 주파수 영역 등화기와 시간 영역 등화기를 설계하였고, 각 경우에 대해 AWGN, ISI, 및 임펄스 잡음 환경에서 시뮬레이션을 통해 성능을 평가하였다. 성능 평가 결과, 잡음환경에 의한 성능차이가 있으나 두 경우 모두 비교적 양호한 등화 성능을 보였으며 시간영역에서 등화기가 주파수영역 등화기보다 전 Eb/No 범위에서 약 1dB 정도 성능이 우수함을 확인하였다.

• 전자공학회논문지A
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• 제33A권11호
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• pp.19-31
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• 1996

Spread spectrum method gurantees good performance in digital communication system under multi-path interference and jamming signals. The purpose of this paper is to develop the wireless modem using DS/SS techinque. The transceiver consists of a spread spectrum DQPSK transmitter and a mtching receiver. The system operates with the chipping rate set to 4 Mcps and the number of chips/symbol at 64, making the data rate 62.5 Kbps using QPSK modilation. The receiver section uses a digital matched filter for fast acquisition of burst signals and uses the comparing the BER of proposed system iwth that of narrow bnd system under various additive white gaussian noises. It is showen that the proposed sysem has better performance than narrow band system. When jamming signals is added to the suggested DS/SS system, we also show that the experimental performance (BER) of the suggested wireless modem is almost same as theroretical performance.

• 대한전자공학회논문지SD
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• 제39권6호
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• pp.69-77
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• 2002

본 논문에서는 캐쉬를 지원하는 ARM940T, TeakLite DSP 코어 그리고 다른 주변 블록이 내장된 0.18㎛ CMOS 공정기술을 적용한 CDMA2000 lx를 지원하는 이동국 모뎀 칩 구현에 대하여 기술한다. 또한 구현 칩을 효율적으로 검증할 수 있는 고유한 검증 방법론과 구현된 칩이 에뮬레이션용 프로세서로 활용될 수 있는 방법을 보인다.

• 전자공학회논문지C
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• 제34C권8호
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• pp.1-7
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• 1997

In tis paper, w eproposed a modeling for direct-sequence spread communication base band modem in RT-level VHDL and implemented in a one-chip VLSI and tested. The transmitter modulates with DQPSK modulation method and spreads a modulated signal with 32-bit PN code into 1.152MHz. The receiver de-spreads a signal using 32-tap matched filter and recovers with DQPSK demodulation method. The digital frequency synthesizer generates the sine signal and the cosine signal of 2.304MHz with ROM tables in the size of 7$\^$*/256 and 6$\^$*/256, respectively. The implemented VLSI has been verified a BER with 10$\^$-4/ at E$\_$b//N$\_$o/ of 13dB with a SPW fixed design model and fabricated in the 0.8.mu.m KG6423 gate array with a VHDL model.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.207-209
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• 1995

The PID controller is widely used due to its fast response and robustness. But its performance is not so good compared with modem controllers such as adaptive, robust, fuzzy, neural controller. Therefore, it is natural to replace PID controller by modem controllers. But, the problem is that modem controller can not be easily applied to the real time process. Hence, this paper proposes such a structure that PID controller and Self-Learning Fuzzy Controller(SLFC) are in parallel with each other. The parameter of SLFC will be updated by gradient descent method using neuro - identifier. The usefulness of this hybrid controller will be proved by simulation results.

• 디자인학연구
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• 제21권
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• pp.55-64
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• 1997

본 논문은 최근 물질 문명에 의해 파생된 환경오염의 심각한 사회적 현상의 대안으로서 현대 텍 스타일에 지속적으로 반영되고 있는‘원시주의’디자인에 관한 연구이다.‘원시주의 개념’을 어원적으로 분석함에 있어서 원시주의를 태동시켰던 현대 예술에 나타난‘원시주의의 발생 및 개념’을 토대로 하여 현대 텍 스타일 디자인에 나타난 사례를 분석 제시한다. 이에 본고는 창의적 디자인 개발을 위한 기초적 자료로서는 물론 아직 활발히 진행되고 있지 않은 현대 텍 스타일 디자인연구의 활성화 및 체계적 정립에 도움을 주는데 그 의의를 둔다.