• 한국정보통신학회논문지
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• 제20권3호
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• pp.607-614
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• 2016

발전소 설비에서 케이블 포설을 위한 설계는 발전소 설비에 사용되어지는 케이블 유형의 다양한 형태로 인해 매우 많은 시간이 요구되고 매우 중요한 과제이다. 케이블 포설 설계 시 레이스웨이(Raceway)는 출발지(Source) 장비로부터 목적지(Destination) 장비까지의 케이블 트레이(Tray) 및 콘디트(Conduit)의 포설 구간을 의미한다. 기존의 케이블 포설 설계 과정은 모두 수기에 의해 작성되어 인적/시간적 투자손실이 크고, 케이블의 누락 및 케이블 오버필(Over Fill)과 같은 비효율적인 손실이 빈번히 발생한다. 따라서 본 논문에서는 효과적인 발전소 케이블 포설 설계를 위한 레이스웨이의 유연한 케이블 오버 필(Fill) 체크 기반의 자동화된 케이블 라우팅 경로 계산 알고리즘을 구현하였고, 제안한 자동화 케이블 라우팅 설계기법은 케이블 위치의 변화에도 유연한 레이스웨이 계산이 가능하다. 구현 결과, 케이블 라우팅 설계 프로그램은 발전소 케이블 포설 설계 사양을 준수하면서 케이블 라우팅 경로를 효과적으로 설정하고, 케이블 포설 설계 시간을 기존 대비 크게 단축하는 성능을 얻을 수 있었다.

• ETRI Journal
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• 제30권1호
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• pp.21-32
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• 2008

Cognitive radio (CR) has been proposed as an effective technology for flexible use of the radio spectrum. The interference between primary users and CR users, however, becomes a critical problem when they are using adjacent frequency channels with different transmission power levels. In this paper, a robust CR orthogonal frequency division multiplexing (OFDM) architecture, which can effectively suppress interference to nearby primary users and overcome adjacent channel interference (ACI) to the CR user, is proposed. This new approach is characterized by adaptive data repetition for subcarriers under heavy ACI, and adaptive time spreading for subcarriers near the borders of the CR user's spectrum. The data repetition scheme provides extra power gain against the ACI coming from primary users. Time spreading guarantees an acceptable interference level to nearby primary users. By computer simulation, we demonstrate that, under a CR environment, the proposed CR OFDM architecture outperforms conventional OFDM systems in terms of throughput and BER performance.

• 한국통신학회논문지
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• 제19권4호
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• pp.729-739
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• 1994

중앙집중 대역확산 패킷라디오 네트워크를 위한 다원접속 방식으로 임의할당-송신기 프로토콜을 새로이 제안한다. 제안하는 임의할당-송신기 프로토콜은 프리엠블 전송시만 경쟁모드로 동작하고, 데이터부분은 의사 직교특성을 갖는 송신기별 확산코드를 사용한다. 종래의 송신기별 프로토콜과 비교할때, 임의 할당-송신기 프로토콜은 프리엠블 전송을 위해 적은 수의 확산코드를 사용하는 경우 중앙수신기의 복잡도를 크게 줄일 수 있다. 이론적인 처리율 분석과 시뮬레이션 결과를 통해 단지 2~3개의 확산코드를 사용하여 프리엠블을 전송하는 경우에 성능이득의 대부분을 얻을 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권4호
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• pp.509-528
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• 2010

The random access systems, with retransmission diversity (RD) employment, over large random spreading code division multiple access (CDMA) channel subject to fading is investigated, under the assumption of infinite number of users and infinite spreading gain with their ratio converging to a constant. The low bound of the signal to interference and noise ratio (SINR) is shown to converge almost surely to a constant. The throughput, spectrum efficiency and energy efficiency in the dominating systems are obtained. The analytical results are confirmed by simulations. We find that in high traffic loads the throughput with fading is higher than that without. When the energy efficiency increases, the spectrum efficiency tends to two contrary values due to SNR increases or decreases. For the ordinary stable systems, the stability region is shown to shrink as the traffic increases and enlarge with RD employment.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 1996년도 학술대회
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• pp.33-38
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• 1996

A multi-media binary DS/CDMA system with variable processing gain and coherent correlation receivers are considered under additive white Gaussian noise channels. Two types of information sources with different rates and transmitting powers are assumed to be transmitted simultaneously in the same channel. Average signal-to-noise ratios at the correlation receiver outputs for each type of information sources are analytically derived as functions of discrete partial cross-correlations between spreading code sequences. The analysis is expected to provide analytical tools for use in preliminary system design and spreading code selection.

• 방송공학회논문지
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• 제24권7호
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• pp.1221-1227
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• 2019

This paper describes a low-density parity-check (LDPC) coded index modulated orthogonal frequency division multiplexing with quasi-orthogonal sequence (IM-OFDM-QOS) and provides performance evaluations of the proposed system. By using QOS as the spreading code, IM-OFDM-QOS scheme can improve the reception performance than IM-OFDM-SS scheme for a given data rate. On the other hand, LDPC code is widely used to the latest wireless communication systems as forward error correction (FEC) scheme and has Shannon-limit approaching performance. Therefore, by applying LDPC code to IM-OFDM-QOS system as FEC scheme, the reception performance can be further improved. Simulation results show that significant signal-to-noise ratio (SNR) gains can be obtained for LDPC coded IM-OFDM-QOS system compared to the LDPC coded IM-OFDM-SS system and the SNR gain increases with the higher code rate.

• 한국통신학회논문지
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• 제26권11B호
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• pp.1540-1545
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• 2001

This paper is concerned with the reverse link performance of multi-code CDMA systems in multipath fading environments. The degree of orthogonality loss among multiple spreading code channels is characterized as the orthogonality factor. It depends on various system parameters including multipath power profiles of propagation channels and the number of Paths resolved at a Rake receiver. The effect of the parameters on the system performance is then investigated in terms of bit error rate and required signal quality. The results show that multipath delay power profiles dominantly affect mutual interference among multi-code channels and multipath combining gain by bandwidth expansion is not so great due to the increase of the mutual interference. Moreover, the orthogonality factor is derived as the value of between (1/m) and 1.

• Journal of information and communication convergence engineering
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• 제2권1호
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• pp.5-8
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• 2004

DS-COMA is now a matured multiple access technology that utilizes spreading codes for user separation. In this paper, we attempt to improve the performance of a multiuser DS-COMA system with a unique chip shaping code called Carrier Interferometry (CI) code. The CI codes exhibit an excellent correlation property that can be used in many applications. In DS-COMA with CI codes (CI/DS-COMA), the symbols are spread by a spreading code and then the chip signals are shaped using a CI code. Due to the correlation property of the CI code, a diversity gain from the shaped chip signals is achieved and the performance of DS-COMA is significantly improved. Comparison study demonstrates that the DS-COMA with CI outperforms the conventional DS-COMA system in multiuser environments.

• 한국디지털정책학회:학술대회논문집
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• 한국디지털정책학회 2007년도 춘계학술대회
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• pp.23-32
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• 2007

Most recently, the development and publication of the ordinance and the manual of policy qualify management is spreading the recognition of quality Control in the public sector. The purpose of this study is to introduce of the system quality Control for local government's policy. So we suggested lessons drew from case study(Daegu metropolitan city, Gumi city) on current introduction. To introduce the system quality Control for local government, we have to gain the sympathy of introduction, second prepare of inducement, last manage PQM flexibility.

• Asian-Australasian Journal of Animal Sciences
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• 제14권1호
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• pp.96-100
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• 2001

Three commercial strains bred in the US (Hubbard), Holland (Lohman), and Canada (Shaver) and Balady breed of chickens were orally infected with $10^6$ cfu of Salmonella gallinarum per chick. Chicks were compared for weight gain, feed intake, feed conversion ratio, mortality rate and contamination of the liver, spleen and intestine with Salmonella gallinarum on the day of slaughter. The Balady chicks had significantly the lowest mortality rate (p<0.01) and weight gain (p<0.001) and poorest feed conversion ratio (p<0.001). Salmonella gallinarum could be shed from the liver, spleen and intestine with alternative rates in all strains. Lohman was the most resistance over the other two commercial strains, while Hubbard had the highest susceptibility. The Balady chicks were the most resistance. However, they may serve as a possible reservoir of Salmonella gallinarum and it may play a role of spreading the infection to the commercial farms in Jordan.