• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.565-568
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• 2002

In this paper, we implement the OFDM Modem which is based on IEEE 802.11a high-speed wireless LAN standard's Physical Layer. We design each functional block based on Standard's PHY parameters and simulate them by using MaxplusII. The OFDM Modem is implemented using $FLEX^{TM}$ FPGA.

• 정보통신설비학회논문지
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• 제11권1호
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• pp.16-22
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• 2012

Wireless data communication is easy to be affected by channel noise and degrade reliability and stability by the multipath fading and ISI compared with wired data communication. In this paper, we designed and implemented indoor wireless modem adopted DQPSK modulation scheme for improvement of bandwidth efficiency, and convolutional encoding, Viterbi decoding and hybrid ARQ algorithm combinig FEC with CRC for efficient error control in indoor wireless channel. Testing the implemented wireless modem, we verified the proposed scheme is proper to efficient and reliable indoor wireless data communication.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(1)
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• pp.73-76
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• 2000

In tendency of digitalization, we studied about the purpose of digital modem for MRI spectrometer and advantage of digital modem compared with analog one. We introduce requirements lot designing transmitter of high speed digital modem for MRl spectrometer We also introduce its top-level and mid-level architecture. The transmitter is composed of CPC-P interface block, DUC & DAC block, RF block, master clock generation block, MCU block. Especially, DUC and its control parts are studied in detail. DUC and DAC can operate up to 52MHz and 100Msps, respectively. However we uses 35MHz as master clock and this paper shows its validity through simulations.

• 전자공학회논문지
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• 제53권7호
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• pp.144-149
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• 2016

본 논문에서는 수중 음향 채널 모델에서 QPSK(Quadrature Phase Shift Keying) 모뎀의 성능을 분석한다. 수중음향채널의 배경잡음과 다양한 환경 파라메터는 수중모뎀의 비트오류율(BER:Bit Error Rate) 성능을 저하시키는 원인이다. 본 논문에서는 이론적인 수중채널모델에서 비부호화된 QPSK와 부호율 2/3의 길쌈부호기를 사용한 부호화된 QPSK의 BER 성능을 분석한다. 수중 음향 통신 시스템의 성능을 개선하기 위해서 파일럿 심볼 기반의 채널 등화 방식을 적용하였다.

• 전기학회논문지
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• 제57권3호
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• pp.488-493
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• 2008

This paper represents a dual-mode type transmission technique for a high reliable narrow-band power line communication(PLC) modem, and its design and implementation of a system-on-chip(SoC). The proposed transmission technique is based on a Chirp modulation for the purpose of overcoming time variations of power line channel environments in the narrow-bandwidth of the frequency range of 95-145.5 kHz. The designed modem is fabricated utilizing a mixed 0.18 ${\mu}m$ CMOS technology. Especially, according to the power line channel environments the data transmission rate can be selectively changed into 2.5 kbps and 480 bps. The total hardware complexity of the implemented chip is about 50,000 gates, the power consumption is about 26mW, and the operating frequency is up to 5.12 MHz.

• 대한가정학회지
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• 제40권8호
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• pp.137-152
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• 2002

The purpose of this study is to analyse the discourses about modem motherhood in Western und Korean society in order to find a new basis for the family policy. The general view that motherhood is merely natural ceased to be valid since the early 1980ties. Nowadays one is rather inclined to define motherhood as a social, cultural and historical fact which goes far beyond the biological dimensions. The concept of motherhood which has been useful to fulfil the industralisation in the modem times cannot be applied to the changed world of our times. The family policy which is closely connected with women must not start from the modem motherhood ideology but from the context of the changed life of woman in our times. I hope that this study could contribute to stimulating the discourse about the family policy which takes into consideration the changed living conditions.

• 음성과학
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• 제11권3호
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• pp.181-192
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• 2004

The metrical structures in orally produced the poetry were generally analyzed by accent, metre and syllable. The purpose of this study is to investigate of metrical structures of Korean modem poetry using computer implemented speech analysis system. Two famous poet's poems confidential talk, Miloe and 'A buddhist dance, Sungmu' were selected for prosodic analysis. The informant is 60 years old professor in major of Korean and French poetry. The syllable structures of poems were analyzed primarily by vowel timbers, which can classified compact and diffuse vowels according to the distance of F2-F1. The perception cues of consonants were analyzed by VOT and tensity features of articulation. Rhythm is classified by dactyl, anapest, trochee, spondee and iambic. As a result, syllable structures of Korean modem poetry were mainly CV and CVC and the reading times of each lines were 3-4sec for 12 and 15 syllables. Main metre of Korean modem poems constructed the Imbic and Anapest. The break of each lines were demarcated by grammatical structure or meaning rather than phonetic structures.

• 한국정보통신학회논문지
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• 제15권4호
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• pp.810-816
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• 2011

기존의 수중음향통신모뎀은 상용 제품들을 기반으로 개발되어 수중음향통신모뎀의 기능 및 성능 구현은 가능하지만 개발 시스템을 제품화하기에는 시스템의 크기나 개발 비용 등에서 단일 플랫폼으로의 시스템 구현이 필수적으로 요구되었다. 따라서 본 논문에서는 수중음향통신모뎀의 단일 하드웨어 플랫폼을 구현함에 있어 중요한 역할을 하는 신호처리 모듈을 TigerSHARC DSP 프로세서를 이용하여 설계 및 구현하고자 한다.

• 제어로봇시스템학회논문지
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• 제13권5호
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• pp.462-466
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• 2007

This paper proposes an automatic bandwidth control method for the performance improvement of Binary Amplitude Shift Keying (BASK) system for Giga-Bit Modem in millimeter band. In order to improve the performance of the BASK system with a fixed bandwidth, the proposed method is to adjust a bandwidth of low pass filter in receiver using the fuzzy system. The BASK system consists of a high speed shutter of the transmitter and a counter and a repeater of receiver. The repeater consists of four stage converters, and a converter is constructed with a low pass filter and a limiter. The inputs to the fuzzy system are the reminder and integral of remainder of counter, and output is a bandwidth. We used a Viterbi algorithm to find the optimum detection from the output of the counter. Simulation results showed that the proposed system improves the performance compared to the fixed bandwidth.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2006년도 하계학술대회
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• pp.162-165
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• 2006

This paper describes a measurement method for electromagnetic field strength of power-line communications(PLC) modem. First it outlines the technology used in PLC modems, and the technical regulation being offered to the technology, from the point of view of its effect on electromagnetic compatibility (EMC). The radio spectrum needs protection from other interferers, and there is a regime in place to provide this protection. Difficulties in achieving compatibility between the requirements for radio protection and the requirements for operation of the PLC modem mean that there is no consensus as yet as to how PLC modem components can be made compliant with EMC requirements globally. It is concluded that there is a measurement method according to CISPR standards which satisfy requirements in domestic regulation.