• 한국통신학회논문지
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• 제19권5호
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• pp.805-814
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• 1994

본 논문에서는 실패상태와 성공상태를 포함시키는 보조 Markov 천이행렬을 이용하여 패킷무선망의 성능을 구할 수 있는 새로운 분석방식을 제시하고 패킷오류 발생이 송신 PRU의 수 X와 수신 PRU의 수 R로 이루어지는 망상태(X, R)의 변화에 미치는 영향을 고려한다. 패킷무선망은 연속시간 Markov 체인 모델 그리고 무선채널은 경판정 Viterbi복호기와 비트변환확산부호계열을 이용한 DS/BPSK CDMA에 대하여 검토한다. 슬롯되지 않은 분산된 다중도약 패킷무선망에서 무선채널의 채널심볼오류가 패킷오류 발생에 미치는 진행과정은 Poisson 분포 그리고 오류발생시간을 지수분포로 가정한다. 신호대 잡음비와 심볼당 확산부호계열의 칩수와 같은 무선채널의 매개변수와 PRU의 수와 허용된 트래픽율과 같은 망의 매개변수를 갖는 함수로 망처리량을 구함으로써 Markov 패킷무선망과 부호화된 DS/BPSK 무선채널을 결합하여 종합적으로 분석할 수 있음을 보인다.

• 한국전자파학회논문지
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• 제16권4호
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• pp.427-437
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• 2005

본 논문에서는 디지털 방송에서 요구되는 디지털 오디오 레벨에 대한 주관적 음향 레벨, 즉 라우드니스의 계측 알고리즘을 실시간화 하는 방법을 제안한다. 이를 위해 객관적 오디오 품질 분석을 위한 권고안인 ITU-RBS1387-1의 분석 결과를 토대로 FFT 기반의 라우드니스 계측 알고리즘을 구현하고, 이 알고리즘을 참조테이블(look-up table)을 이용하여 실시간화 하는 방법을 제시하였다. 그리고 이 알고리즘의 성능과 계측 시간 분석을 위해 23개의 순음과 30개의 디지털사운드 샘플을 적용하고, 그 결과를 분석하였다. 실험결과를 살펴보면, 실시간화 된 알고리즘의 계측값은 실시간화 방법이 적용되지 않은 원래 알고리즘과 비교할 때, spectral spreading관련 참조테이블의 레벨 해상도가 $10\;\cal{dB}$로 상당히 큰 경우에도 $2\;\%$미만의 차이를 보여 매우 양호한 측정 결과를 보였다. 계측 시간의 감소 효과를 살펴보면, 알고리즘 전체적으로는 1/21 정도로 실행시간이 줄었으며, 가장 계측시간 점유비율이 근 청각필터 그룹변 에너지 계산 시간은 1/450로 줄어들고, 여기 패턴을 구하는 계산 시간도 약1/3.57로 좋은 계측 시간 단축 효과를 얻었다. 결론적으로 제안한 알고리즘을 통해 향후 DSP 기반의 완전 실시간 라우드니스 미터를 구현할 가능성을 확보하게 되었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 ICEIC The International Conference on Electronics Informations and Communications
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• pp.302-309
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• 2004

The transmission capacity of wireless communication systems may become dramatically high by employ multiple transmit and receive antennas with space-time coding techniques appropriate to multiple transmit antennas. For large number of transmit antennas and at high bandwidth efficiencies, the receiver may become too complex whenever correlation across transmit antennas is introduced. Reducing decoding complexity at receiver by combining array processing and space-time codes (STC) helps a communication system using STC to overcome the big obstacle that prevents it from achieving a desired high transmission rate. Multi-carrier CDMA (MC-CDMA) allows providing good performance in a channel with high inter-symbol interference. Antenna array, STC and MC-CDMA system have a similar characteristic that transmit-receive data streams are divided into sub-streams. Thus, there may be a noticeable reduction of receiver complexity when we combine them together. In this paper, the combination of array processing and STC in MC-CDMA system over slow selective-fading channel is investigated and compared with corresponding existing MC-CDMA system using STC. A refinement of this basic structure leads to a system design principle in which we have to make a trade off between transmission rate, decoding complexity, and length of spreading code to reach a given desired design goal.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 추계 학술논문 발표대회
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• pp.28-29
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• 2015

Due to the big fire in Uijeongbu, the status of construction, fireproof materials and structural method were examined to prevent fire propagation through outside insulation parts of urban living homes. Through research and experiments, the following results were obtained. It was confirmed that outside heat-insulation wall method was used in a large number of urban living homes which were made of materials and structures spreading fire easily.Through experiments, it was revealed that lightweight plate material, as a fireproof material, can save the cost as well as the period of construction and obtain more than 30 minutes of evacuation time which is twice the maximum evacuation time.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2003년도 가을 학술발표논문집 Vol.30 No.2 (3)
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• pp.172-174
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• 2003

송신단에 다중안테나를 사용하는 송신 다이버시티 기법에 대한 연구가 최근 활발히 이루어지고 있다. 본 논문에서는 CDMA(Code Division Multiple Access)2000과 3GPP(The third generation partnership project)에서 고려한 개루프 송신 다이버시티 기법인 STTD(Space time transmit diversify), OTD (Orthogonal transmit diversity), STS(Space time spreading)를 다수 반송파 CDMA 시스템에 적용시킬 경우 하향링크 (Downlink)에서의 성능을 평가한다. STS와 STTD방식은 동일한 성능을 보이지만 STS방식은 복잡도와 높은 PAR(Peak to average ratio)의 단점을 보이며, OTD는 이 두 방식에 비해 성능이 떨어지는 것을 보여준다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.439-442
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• 2002

The interface between two different materials in the insulation systems is the weak-link in the underground power transmission systems, In this paper, Optimum conditions of the interface between Epoxy and EPDM is studied. The variation factor condition of interface is roughness of surface, spreading of oils, interfacial pressure and temperature. The breakdown times under the constant voltage below the breakdown voltage were also gained. The breakdown voltage at the after laying time equivalent to is calculated by the V-t characteristic and the inverse power law. When this is done, the characteristic life exponent n is used and the long time breakdown voltage can be evaluated.

• Journal of Acupuncture Research
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• 제25권6호
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• pp.153-161
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• 2008

Objectives : This study was designed to find out whether normal saline(NS) acupuncture is able to be constituted as an appropriate control group for Cervi Cornu Parvum herbal acupuncture(CC). Methods : NS and CC were injected into Quchi($LI_{11}$) of the subjects. The subjects completed a questionnaire rating the intensity of 21 kinds of acupuncture sensation(hurting, penetrating, sharp, aching, intense, spreading, radiating, tingling, pricking, stinging, pulling, heavy, dull, numb, electric, shocking, hot, burning, cool, pulsing, and throbbing) and side effects. We compared subjective evaluations of acupuncture sensation and side effects between two groups. Results : As for CC most of the acupuncture sensation items were not significantly different from NS especially in less acupuncture-experienced subjects(average 2, below 10 time experiences) rather than more acupuncture-experienced subjects(above 10 time experiences). Conclusions : We found that NS might be an appropriate placebo herbal acupuncture for CC in small amount of acupuncture-experienced subjects. Further study is needed for new placebo herbal acupuncture for CC in more acupuncture-experienced subjects.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2011년도 추계학술논문발표회 논문집
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• pp.478-481
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• 2011

This study is intended to evaluate and optimize the characteristics of smoke spreading and the appropriateness of evacuation time extended by operation of smoke control system during fire within the underground space of the building structured in compliance with the smoke control system performance criteria from the local fire safety standard, which has been currently applied to the buildings in Korea. Using the heat release per unit weight of the combustibles, a numerical analysis both in case of smoke control system in operation and the system not in operation was carried out at the several different shopping malls. From the viewpoint of securing the evacuation time, the results were compared in an attempt to assess the appropriateness of the fire safety criteria.

• 대한조선학회논문집
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• 제41권1호
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• pp.1-7
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• 2004

GUI program for analyzing directional spectrum waves is introduced in this paper Basically, MLM (Maximum Likelihood Method) was used for this program which was additionally consisted of performing spectral and time domain analysis for two dimensional irregular waves. Moreover, the directionality of directional spectrum waves generated by single summation and double summation method was investigated based on MLM. The directionality from each summation method has good agreement compared with that of target wave spreading function in the case of single wide directional spectrum waves. In addition to this, the resolution of directionality in double summation method was investigated as introducing coherence function between each wave component

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1978-1980
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• 2000

Because the interfaces between two different materials are the weak-link in the underground power transmission systems, they affects the stability of insulation systems. In this paper, Epoxy/EPDM interface is selected and investigated the optimum condition by variation of interfacial conditions such as roughness of surface, spreading of oils, interfacial pressure and temperature. The breakdown times under the constant voltage below the breakdown voltage were also gamed. The breakdown voltage at the after laying time equivalent to is calculated by the V-t characteristic and the inverse power law. When this is done. the characteristic life exponent n is used and the long time breakdown voltage can be evaluated.