• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.8
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• pp.1337-1345
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• 2000

In spite of the advantages of lightweight, low profile, and mass productions, microstrip array antenna has inherently the scan blindness problems in case of wide angle scan. And this scan blindness can be overcome by using cavity-backed microstrip radiator. In this paper, we presented the algorithm of analyzing skewed cavity-backed microstrip array and verified the validity of the proposed numerical results with those of reference papers. Finally, we show the effect of cavity-backed and skewed grid array structure.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.4
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• pp.86-94
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• 2009

Currently, positioning methods for LBS(Location Based Service) are GPS and network-based positioning techniques that use mobile communication networks. In these methods, however, the accuracy of positioning decreases due to the propagation delay caused by the non-line-of-sight(NLOS) effect and the repeater. To address this disadvantage, the CDMA system uses Pattern Matching algorithm. The Pattern Matching algorithm constructs a database of the propagation characteristics of the RF signals measured during the GPS positioning along with the positioned locations, so that the location can be provided by comparing the propagation characteristics of the received signals and the database, upon a user's request. In the area where GPS signals are not received, however, a database cannot be constructed. There are problem that the accuracy of positioning decreases due to the area without a database Because Pattern Matching algorithm depend on database existence. Therefore, this paper proposed a pilot signal strength prediction algorithm to enable construction of databases for areas without databases, so as to improve the performance of the Pattern Matching algorithm. The database was constructed by predicting the pilot signals in the area without a database using the proposed algorithm, and the Pattern Matching algorithm analysed positioning performance.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2004.03a
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• pp.399-406
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• 2004

최근 급속한 도시의 팽창과 산업의 발전으로 인하여 가스시설은 급속히 확대되고 있는 실정이다. 이러한 가스시설물의 중요성을 인식하고 많은 도시가스업체에서는 가스관망 시설정보를 전산화하여 항상 최신의 현황을 유지할 수 있는 가스시설물관리시스템을 개발하여 사용하고 있다. 그러나 이러한 시스템은 가스시설물의 현황파악 및 유지관리를 위한 기본적인 기능만을 제공하는 관계로, 가스 누출사고 발생시 정확한 사태의 파악과 함께 신속한 대책 마련을 위한 의사결정 지원이 어려운 실정이다. 따라서 체계적인 가스사고관리를 수행할 수 있는 응용시스템의 필요성이 증대되고 있다. 이러한 시점에서 본 연구에서는 가스사고분석을 신속하고 체계적으로 수행할 수 있는 가스사고관리 적용알고리즘 분석 및 최적의 알고리즘을 정립하여 가스사고관리시스템을 구현하였다. 본 연구를 통한 결과는 1ㆍ2차 차단밸브의 산정이 가능해짐으로써 빈번한 가스 누출사고 발생시 실시간으로 적정대처방안의 제시가 가능하게 되었다. 또한, 누출 최대가스량을 제시함으로써 누출에 대한 피해예상 분석을 위한 정보 제공 및 가스의 신속한 재공급을 위해 필요한 의사결정 지원 정보의 제공이 가능하게 되었다. 아울러, 가스누출사고에 의한 가스공급중단 관로 및 수용가에 대한 속성현황의 파악은 물론 시각적인 도식을 통한 전체적 현황파악이 가능하였다. 이러한 가스사고관리시스템의 개발을 통하여 사고 발생시 신속한 사고방안 제시 및 사고피해의 최소화를 위해 필요한 의사결정 지원 정보의 제공이 가능하게 됨으로써 국민의 안전 및 복지와 도시가스업체의 업무 효율화로 인한 예산절감 효과를 기대할 수 있다. 가시권 분석기능을 이용하여 실제 지형공간상에서 전파경로 손실치를 도시화함으로써 전파관리자가 무선서비스지역 설계, 전파음영지역 판단, 최적 중계기와 기지국 위치 선정에 기여할 것으로 판단된다.하지 않은 지역과 서로 다른 분광특성을 나타내므로 별도의 Segment를 형성하게 된다. 따라서 임상도의 경계선으로부터 획득된 Super-Object의 분광반사 값과 그 안에서 형성된 Sub-Object의 분광반사값의 차이를 이용하여 임상도의 갱신을 위한 변화지역을 탐지하였다.라서 획득한 시추코아에 대해서도 각 연구기관이 전 구간에 대해 동일하게 25%의 소유권을 가지고 있다. ？스굴 시추사업은 2008년까지 수행될 계획이며, 시추작업은 2005년까지 완료될 계획이다. 연구 진행과 관련하여, 공동연구의 명분을 높이고 분석의 효율성을 높이기 위해서 시료채취 및 기초자료 획득은 4개국의 연구원이 모여 공동으로 수행한 후의 결과물을 서로 공유하고, 자세한 전문분야 연구는 각 국의 대표기관이 독립적으로 수행하는 방식을 택하였다 ？스굴에 대한 제1차 시추작업은 2004년 3월 말에 실시하였다. 시추작업 결과, 약 80m의 시추 코아가 성공적으로 회수되어 현재 러시아 이르쿠츠크 지구화학연구소에 보관중이다. 이 시추코아는 2004년 8월 중순경에 4개국 연구팀원들에 의해 공동으로 기재된 후에 분할될 계획이다. 분할된 시료는 국내로 운반되어 다양한 전문분야별 연구에 이용될 것이다. 한편, 제2차 시추작업은 2004년 12월에서 2005년 2월 사이에 실시될 계획이다. 수백만년에 이르는 장기간에 걸쳐 지구환경변화 기록이 보존되어 있는 ？스굴호에 대한

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.9 s.351
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• pp.32-39
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• 2006

5.8GHz DSRC(Dedicated Short Range Communications) is a short to medium range communications service that supports both public safety and private operations in roadside to vehicle and vehicle communication. However the 5.8GHz frequency may cause the shadowing effect or communication blocking problem when there is an obstacle or another vehicle between RSE (Road Side Equipment) and OBE (On Board Equipment). In this paper, to solve this problem of the 5.8GHz DSRC, we propose a relay protocol based on the standard of DSRC radio communication between RSE and OBE in the 5.8GHz band made by TTA (Telecommunication Technology Association). By using the proposed relay protocol to DSRC system and intervehicle communication, we also consider a fixed relay protocol and mobile relay protocol. We expect to apply this relay protocol for the DSRC intervehicle communication and video communication between drivers and safe distance among vehicles in the near future.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.5 s.347
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• pp.113-120
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• 2006

This thesis deals with solutions such as coverage area extension, reduction of the shadow region and performance enhancement of handover caused by structural modification of WiBro network. The More far the distance of RAS(Radio Access Station) and SS(Subscriber Station) is in micro cell, the more bad the quality of channel environment becomes owing to radio interference. Consequently, it causes the deterioration of the throughput and also the deterioration of communication quality in many sides. In fact, most users of WiBro are located in the region, the QPSK region which is bad in point of channel quality. It brings the service complaint by user. We select RS(relay station) to solve the matter caused by channel environment in this cell, and extend coverage and improve the performance of handover call blocking.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.957-962
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• 2016

Current terrestrial Digital Multimedia Broadcasting (T-DMB) is conducting the emergency alert broadcast, or can view a variety of broadcasting. However, propagation shadow area is a situation where the service is limited due to limitations of facilities investment. In addition, there is the problem of T-DMB broadcasting is for viewing only a restricted area and a mobile device because the mobile is also T-DMB viewing device impossible. In this paper, it receives a T-DMB broadcasting as a way to solve the problems of the T-DMB system, which was studied the re transmission to the mobile device. Accordingly, by receiving the broadcast may be watched in the mobile device the T-DMB reception impossible. Also provides a one-way/two-way authentication mechanism using a conditional access function, and the system was configured so that the user can watch only the registered broadcasting.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.12
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• pp.718-728
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• 2014

The multi-band wireless local area network (WLAN) using 60 GHz band and the lower band (typically 2.4 GHz/5 GHz band) can support the very high data rate in short-distance communication using 60 GHz band and the long-distance communication using the lower band. For heightening the efficiency of multi-band WLAN, an band selection scheme is a necessity. In this paper, we propose an effective frequency band selection scheme for multi-band WLANs. By using computer simulation with NS-3, we show the performance of the proposed schemes when the stations suffer from the human blockage and the log-normal shadowing.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.10
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• pp.13-20
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• 2013

Currently, SEAMCAT has been widely used as a tool to evaluate the effects of interference among wireless communication systems. In the previous work, we have incorporated the ITU-R P.526 pathloss model to the existing SEAMCAT in order to support the capability of interference evaluation taking into account any specific terrain characteristics. Along with this, we have implemented a terrain display function based on the Google map. However, the two-dimensional Google map based display is not effective in helping users to figure out some terrain features including the elevation variation in a given region. In order to alleviate this difficulty, we have incorporated the three-dimensional terrain display using the API of the Google earth to the existing SEAMCAT and provided the capability of viewing the positions of the associated communication systems, the variation of the carrier intensity and interference intensity in location, shadow region indication, and line-of-sight analysis and presented an example of interference evaluation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.5
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• pp.665-675
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• 2001

In this paper, the reverse link performance of a imperfect power controlled DS/CDMA cellular system that uses a base station array antenna which can effectively remove the multiple access interference is analyzed considering both beam forming algorithm and power control error in shadowing. The blocking probability of the DS/CDMA cellular system based on array parameters, $E_b/N_o$ and statistics of interference is derived, and then the system capacity corresponding to a certain blocking probability is calculated. On the assumption that the blocking probability is set 1%, the system capacity using MCGM algorithm with 12 antenna arrays is more increased maximum 32 times than that using a omni-directional antenna and about 2 times than that using MMSE algorithm, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.4
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• pp.313-322
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• 2003

In this paper, the reverse link performance of imperfect power controlled cdma2000 cellular system that using array at a base station is analyzed, when MCGM beamforming algorithm and power control error is considered in shadowing. The blocking probability of the cdma2000 cellular system based on array parameters, E$\_$b//N$\_$0/ and interference statistics is calculated, and then the system capacity is calculated at a specific blocking probability. When the blocking probability is set 1 %, PCE(power control error) is 2 dB, M=2, 4, 8, 10, the capacity of cdma2000 is increased 2.3 ∼ 2.5 times higher than IS-95.