• Journal of Korea Multimedia Society
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• v.9 no.11
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• pp.1410-1420
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• 2006

In this paper, a replica update propagation method for cost optimization of request forwarding in the Grid database is proposed,. In the Grid database, the data is replicated for performance and availability. In the case of data update, update information is forwarded to the neighbor nodes to synchronize with the others replicated data. There are two kinds of update propagation method that are the query based scheme and the log based scheme. And, only one of them is commonly used. But, because of dynamically changing environment through property of update query and processing condition, strategies that using one propagation method increases transmission cost in dynamic environment. In the proposed method, the three classes are defined from two cost models of query and log based scheme. And, cost functions and update propagation method is designed to select optimized update propagation scheme from these three classes. This paper shows a proposed method has an optimized performance through minimum transmission cost in dynamic processing environment.

• The Journal of the Acoustical Society of Korea
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• v.19 no.5
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• pp.53-59
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• 2000

In this paper, considering configuration of the earth and environment of country, it is classified a radio propagation environment Multipath propagation measuring system based on PN code correlation detection method is built to study a wave propagation characteristics of 1.95GHz. Considering the characteristic artificial structure of country, Cihwa plant superintendent area has been selected for basic and accurate measurement a radio propagation characteristic. The experiments are carried out with respect to the RMS delay Spread and the received power in the two kind of geographical areas, LOS (Line of Sight) and N-LOS (Non Line of Sight). The measurement result of that received power of LOS area is -1.6∼-28.8dBm, RMS delay spread is 0.023㎲∼0.22㎲ and received power of N-LOS area is 16∼36.5dBm and RMS delay spread is 0.068∼0.37㎲.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.1003-1013
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• 2009

In the domestic environments, there are many tunnels since most of terrains have mountains. To ensure the quality of wireless network service in NLOS environment like tunnels which differ from indoor or outdoor wireless channels, researches on wave-propagation characteristics. through such channel are necessary. Especially, in such environment the ground repeater called Gap-Fillers are usually used for satellite mobile services. To make sure that mobile service using satellites in tunnels is available, the research about Gap Filling method is essential. This research is focus on the characterising the wave-propagation through tunnels, to find the appropriate frequency, HPBW of the Gap-Filler antennas, the number of Gap-Fillers, etc. In this paper, we present the effective Gap Filling method in tunnels for ISM band, based on analysis of ray tracing and measurement results.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.6
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• pp.181-187
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• 2012

In satellite communication system, propagation characteristics analysis of the receiving environment is very important, because radio quality is changed by the receiving environment. Unlike Terrestrial wireless communications, satellite communication is affected by altitude and atmospheric environment. Therefore, there are many factors to consider for propagation characteristics analysis. In this paper, signal reception environment of geostationary earth orbit was analyzed on urban environment. In order to analyze the propagation simulation, virtual buildings was established and reception environment was changed. The results of this paper would help to design the satellite mobile communication systems in Ka-band.

• The Journal of the Korea Contents Association
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• v.4 no.2
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• pp.21-27
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• 2004

In an urban area telecommunication using wireless system, the accurate prediction and analysis of wave propagation characteristics are very important to determine the service area optimized selection of base station, and eel design, etc. In the stage of these analyses, we have to present the propagation prediction mood which is varied with the type of antenna, directional angle, and configuration of the ground in our urban area in addition we need to perform an analysis of the conventional mode which is similar to ours and dig out the parameters to evaluate the wave environment before the cell design for the selected area. In this paper, we propose a wave propagation prediction model concerning the topography and obstacles in our urban area. We extract the parameters and apply them to the proposed wave environment for the simulation analyzing the propagation characteristics. Throughout these analyzing procedure, we extracted the essential parameters such as the position of the base station, the height of topography, and adequate type and height of the antenna with our preferable cuteness.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.9
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• pp.1822-1829
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• 2016

DGPS Reference station is established in Korea for improvement of GPS navigation accuracy and needs of integrity. Recently, DGPS stations provide user positioning information on land as well as ocean. However, this paper investigated visibility and interference environment for performance degradation of Chung-ju DGPS reference station. In case of Young-do reference station, visibility and interference environment were satisfied with reference standard. In case of Chung-ju reference station, visibility was satisfied with 7 degree elevation angle. However, interference environment was not satisfied with reference standard of -50dBm. This paper proposed time differential measurement analysis method excluding error of signal noise for analyzing measurement error. Chung-ju reference station measurement analysis result is three times the error than on Young-do in Dec, 2015. In addition, this paper has confirmed measurement performance degradations because of reference station equipment problem. Future study will be carried out performance analysis of 17 DGPS reference station.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.875-878
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• 2010

In this paper, we proposed a RSSI based cooperative localization algorithm considering wireless propagation characteristics in indoor environment for wireless sensor networks, which can estimate the BN position. The conventional RSSI based estimation scheme has low precision ranging according to time variable propagation characteristics. Hence, we implemented ray-launching simulator for analysis of propagation characteristics in $13.65m{\times}8.7m$, and performed proposed localization scheme with 4 RN and 1 to 5 BN. From the results, if we can consider channal characteristic in proposed ranging scheme, the cooperative localization algorithm with propagation characteristics provides higher localization accuracy than RSSI based conventional one.

• The Journal of the Acoustical Society of Korea
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• v.18 no.8
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• pp.100-107
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• 1999

When a subscriber service composed along the central street of urban in microcell and picocell mobile communication of cellular method, we proposed the propagation prediction model that mobile communication environment of urban can analyze exactly and faster men than a precedent. We simulate the proposed propagation prediction model under the urban propagation environment of PCS mobile communication and analyze distribution of received field strength in cell. As a results, we show the optimal condition of the transmitting power and the position of the base station in the microcell and the picocell mobile communication.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.63-63
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• 2017

우리나라에서 홍수기에는 하천에 부유사를 포함한 수체가 침강되어 하층 밀도류 형태로 전파된다. 온도로 성층화가 심하게 되지 않은 댐의 경우 하층 밀도류로 댐체까지 전파되고, 유출되어 하류로 흘러가거나 차단되어 담수된다. 침사용 저수지는 하류에 있는 저수지에 유사 전파를 막기 위해 건설된 댐으로, 이를 잘 관리하기 위해서는 밀도류의 차단에 대한 연구가 필수적이다. 따라서 본 연구의 목적은 층적분 모형을 사용하여 밀도류의 전파와 이에 따른 저수지의 유사 차단 현상을 모의하는 것이다. 이를 위하여 1차원 수치모형을 제시하였으며 실내실험 자료에 적용하여 밀도류의 전파 및 차단 양상을 분석하였다. 모의 결과 소류사는 대부분 상류단에서 퇴적되고, 부유사가 밀도류에 포함되어 하류단까지 전파되고, 차단되는 것을 확인하였다. 또한, 질량보존과 운동량 보존에 의해 저수지 전체에서 밀도류 두께가 증가되며 담수되는 현상을 확인하였다. 담수된 밀도류의 포집효율에 영향을 미치는 인자를 분석하고, 포집효율에 대한 각 입자의 민감도 분석을 수행하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.3
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• pp.296-303
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• 2014

In this paper, we propose an algorithm to visualize radio wave environment based on the measured Received Signal Strength Indication( RSSI) and 3D geographic information. We estimate the source position using the circumcenter of the triangle and visualize the radio wave environment using the empirical propagation models. A mode seeking algorithm(mean-shift clustering) is used to seek the peak points and the center of gravity is utilized to reduce the estimation errors. Our approach finds its applications in the radio wave monitoring systems for the efficient utilization of radio resources.