• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.10
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• pp.4865-4886
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• 2017

The user experience of practical indoor power line communication (PLC) applications is greatly affected by the system quality-of-service (QoS) criteria. With a general broadcast-and-multi-access (BMA) relay scheme, in this work we investigate the joint source and relay power optimization of the amplify-and-forward (AF) relay systems used under indoor broad-band PLC environments. To achieve both time diversity and spatial diversity from the relay-involved PLC channel, which is time-varying in nature, the source node has been configured to transmit an identical message twice in the first and second signalling phase, respectively. The QoS constrained power allocation problem is not convex, which makes the global optimal solution is computationally intractable. To solve this problem, an alternating optimization (AO) method has been adopted and decomposes this problem into three convex/quasi-convex sub-problems. Simulation results show the fast convergence and short delay of the proposed algorithm under realistic relay-involved PLC channels. Compared with the two-hop and broadcast-and-forward (BF) relay systems, the proposed general relay system meets the same QoS requirement with less network power assumption.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.101-104
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• 2006

다중 레벨 공간 DBMS 는 디스크 기반 DBMS 와 메인 메모리 저장관리자를 통합한 시스템이다. 다중 레벨 공간 DBMS 는 디스크 기반 DBMS 를 사용하여 대용량 데이터를 저장하고 자주 이용되는 데이터만 스냅샷으로 메인 메모리에 상주 시켜 빠르게 트랜잭션을 처리한다. 그러나 시스템 운영상에서 스냅샷의 중복 생성 및 부적절한 갱신 주기의 문제가 발생하여 시스템의 성능을 저하시킨다. 그래서 본 논문에서는 스냅샷 데이터 관리를 위한 관리도구를 제안한다. 본 관리도구는 스냅샷의 생성 및 삭제, 동기화 등의 조작 기능을 제공하고, 메타데이터를 관리하여 통계정보 및 스냅샷 상세정보를 제공하여 최적화를 위한 판단기준으로 사용 할 수 있도록 한다. 본 도구를 이용하면 관리자가 시스템이 발견하지 못한 스냅샷의 중복된 영역 및 최적인 갱신 주기를 판단 하고 스냅샷을 조작해 시스템의 성능을 보다 최적 할 수 있다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.36 no.5
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• pp.381-394
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• 2018

An address is sub-spatial data representing a location, and identifies the place in which a resident's life is based. The Korean address system has changed from an area-based address system to the Road Name Address System in 2014 to solve the problems of the area-based address system and to accept the international address standards. Although the Road Name Address System is continually being modified and implemented it limitations. Therefore, the purpose of this study is to resolve these limitations and to analyze and redefine the Road Name Address System of Korea to implement the street-based address system. To understand the address, we define the components of the address system and analyze the Korean Road Name Address System based on each component to derive the limit. To resolve the limitations of the Road Name Address System and to implement the street-based address system, the Road Name Address System is redefined according to three aspects. Finally, we evaluate the usability of the Road Name Address System proposed in this study through address based geocoding.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.5
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• pp.81-90
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• 2007

Watershed topographical information is required in hydrologic analysis, supporting efficient hydrologic model operation and managing water resources. Watershed topographical data extraction systems based on desktop GIS are abundant these days placing burdens for spatial data processing on users. This paper describes development of a Web-based Geographic Information Systems that can delineate the Geum River sub-basins and extract watershed topographical data in real time. Through this system, users can obtain a watershed boundary by selecting outlet location and then extracting topographical data including watershed area, boundary length, average altitude, slope distribution about the elevation range with Web browsers. Moreover, the system provides watershed hydrological data including land use, soil types, soil drainage conditions, and NRCS(Natural Resources Conservation Service) curve number for hydrologic model operation through grid overlay technique. The system operability was evaluated with the hydrological data of WAMIS(Water Management Information System) with the government operation Web site as reference data.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.4
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• pp.275-280
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• 2015

In this paper, we studied for modified MUSIC algorithm of direction of arrival (DOA)estimation. Modified MUSIC algorithm search optimal covariance matrix using singular value decomposition and Bayes method, and desired signals are estimated by updating weight. In order to estimation of desired signals, we used sub spatial method of MUSIC algorithm. General MUSIC algorithm can estimate a desired signal in case of non-correlation signal. But, general MUSIC algorithm in case of correlation signal can not estimate a desired signals and resolution is decreased. Though simulation in case of correlation signal, we analyze to compare proposed MUSIC algorithm with general MUSIC algorithm.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.2
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• pp.249-258
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• 2008

Historical emission data for 11 polychlorinated biphenyls (PCBs) and a regional multimedia environmental model, CoZMo-POP 2, were used to predict air concentrations and congener patterns in Korea. The total emission value for South Korea was allocated to sub-provinces and cities based on their population. The spatial distribution of PCB emissions was generally correlated with that of measured atmospheric levels, suggesting that population could be a good surrogate for the intensity of PCB emission in Korea. The simulated time trends of air concentrations well reflected those of emission with a peak in the mid-1970s and insignificant levels in the 2030s. The model predicted that the contribution of volatile PCBs had increased after emission reduction iii the 1970s. This trend would continue until the early 2030s. The measured and modeled PCB levels in the 2000s were in an agreement of an order of magnitude, and their congener patterns were very similar. Consequently, despite of high uncertainty for emission estimates, the emission data for Korea used in this study is considered to be reliable. The results of this study could be compared with simulation data based on a new emission inventory to be developed by measurements in the near future.

• Fisheries and Aquatic Sciences
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• v.11 no.1
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• pp.50-60
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• 2008

Harmful algal blooms (HABs) of Cochlodinium polykrikoides frequently occur around the South Sea of Korea, causing. economic losses in coastal breeding grounds. HAB outbreak scale usually changes each year depending on physical, biological and environmental conditions. Relatively large-scale HABs occurred in 1995, 1997, 1999, 2001, 2002 and 2003 with respect to spatial scale, duration and maximum density. Considering HAB scale and temperature distributions around the South Sea, we found that low coastal temperatures in August correspond to enormous HAB outbreaks. Cold waters created by coastal upwellings around the southeastern coast of Korea also corresponded to these outbreaks. Serial oceanographic investigations in August in the South Sea revealed that sea surface temperature anomalies had distinctively negative values when large-scale HAB outbreaks appeared. With regard to temperature differences between the surface and the 30-m layer, there was a tendency for large-scale outbreaks when temperature gradients around the seasonal thermocline weakened.

• Journal of Korean Society for Geospatial Information Science
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• v.12 no.4 s.31
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• pp.75-81
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• 2004

Because geological types and land cover conditions of Imha basin have a very weak characteristics to soil erosion, most soil particles (low into river and bring about high density turbidity in Imha reservoir when it rains a lot. This study used GIS-based RUSLE model and analyzed soil erosion to make basic data for the countermeasures of turbidity reduction in Imha reservoir. Total soil erosion amounts was evaluated as 5,782,829 ton/yr using rainfall data(2003) and especially Dongbu-basin was extracted as most source area or soil erosion among Imha sub-basin. Also it was evaluated that soil erosion amount by RUSLE model was suitable by applying turbidity survey data.

• Journal of Forest and Environmental Science
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• v.31 no.3
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• pp.225-234
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• 2015

Mangroves are important coastal ecosystems and are located at the inter-tidal zones of tropical and sub-tropical belts. The global mangrove forests are declining dramatically because of the conversion of forests to shrimp farming, over-exploitation, pollution and freshwater diversion. The Bangladesh Forest Department initiated mangrove afforestation throughout the coastal belts of Bangladesh in 1966 to provide better protection for the coastal communities. Up to 1990, 120,000 ha of mangroves had been planted and it is one of the largest coastal afforestaton programs in the world. The objective of this study is to exploit the spatial extent of mangrove plantation and their dynamics of changes over the last two decades using multispectral Landsat imagery. The study area covers the coastal areas of Bangladesh that is extended over the eastern part of Sundarbans up to Teknaf, the southern tip of mainland Bangladesh. Mangrove plantations were interpreted visually on computer screen and interactive delineation of forest boundary was done. The mangrove plantation area has been estimated as 32,725, 47,636 and 43,166 ha for the year of 1989, 2000 and 2010, respectively. Mangrove deforestation by human activity has increased almost six times in the recent decade in comparison to the previous one. The mangrove forest loss due to coastal erosion has slightly declined in the 2000s. Mangroves have been lost primarily because of agricultural expansion. The result of this investigation will be helpful to understand the dynamics of mangrove plantation and the main drivers of changes in this coastal ecosystem.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.1 s.104
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• pp.8-16
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• 2006

In this paper, updating schemes for the alternating-direction implicit finite-difference time-domain method(ADI-FDTD) are studied, which method has the potential to considerably reduce the number of time iterations especially in case where the fine spatial lattice relative to the wavelength is used to resolve fine geometrical features. In numerical simulations for microwave structure using ADI-FDTD, time marching scheme comprises of two sub-iterations. Two different updating equation sets for ADI-FDTD simulations are presented. In order to discuss the characteristics of those schemes especially in view of applying boundary conditions, we solved two complementary 2-D problems.