• Journal of KIISE:Databases
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• v.29 no.5
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• pp.367-380
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• 2002

Due to recent increase in applications requiring huge amount of data such as spatial data analysis and image analysis, clustering on large databases has been actively studied. In a hierarchical clustering method, a tree representing hierarchical decomposition of the database is first created, and then, used for efficient clustering. Existing hierarchical clustering methods mainly adopted the bottom-up approach, which creates a tree from the bottom to the topmost level of the hierarchy. These bottom-up methods require at least one scan over the entire database in order to build the tree and need to search most nodes of the tree since the clustering algorithm starts from the leaf level. In this paper, we propose a novel top-down hierarchical clustering method that uses multidimensional indexes that are already maintained in most database applications. Generally, multidimensional indexes have the clustering property storing similar objects in the same (or adjacent) data pares. Using this property we can find adjacent objects without calculating distances among them. We first formally define the cluster based on the density of objects. For the definition, we propose the concept of the region contrast partition based on the density of the region. To speed up the clustering algorithm, we use the branch-and-bound algorithm. We propose the bounds and formally prove their correctness. Experimental results show that the proposed method is at least as effective in quality of clustering as BIRCH, a bottom-up hierarchical clustering method, while reducing the number of page accesses by up to 26～187 times depending on the size of the database. As a result, we believe that the proposed method significantly improves the clustering performance in large databases and is practically usable in various database applications.

• Journal of the Korean association of regional geographers
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• v.15 no.1
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• pp.16-35
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• 2009

This paper is to compare the contexts and old place names in old county maps of Goryeong-hyeon(高靈縣) according to the four types of maps. 23 maps covering Goryeong-hyeon were collected from the old county-map atlas(郡縣地圖帖) and Eupji(邑誌). The first type(named 'picture county map') included 8 county-maps in which information of military, and administrative contents are mainly mapped. The second type(named '1-ri grid system map') included 4 county maps in which information about beacon routes and road systems were regarded as very important. The third type(named '20-ri grid-system map(方眼地圖)' included 4 county-maps which were drawn as same scale with 20-ri(里) grids. The fourth type(named 'local county-map(地方郡縣地圖)' included 5 county maps which were drawn by local mappers. Types of toponyms which were included in maps are different by the propose of map-drawing. In the picture county maps, place names from military, and administrative contents are written. In the 1-ri grid system county maps, place names especially from military and transportation are fluent. In the 20-ri grid system county maps, generic name from natural environment, such as mountains are very fluent. In the local county maps, city-walls and castles are drawn exaggeratively and detailed generic name from warehouses and villages are written in those maps. This study shows that Daedongyeo-jido was drawn on the basis of 20-ri grid system county maps with the supplementation of geographical information.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.11
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• pp.3-11
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• 2015

An advanced receiver which can manage inter-cell interference is required to cope with the explosively increasing mobile data traffic. 3rd Generation Partnership Project (3GPP) has discussed network assisted interference cancellation and suppression (NAICS) to improve signal-to-noise-plus-interference ratio (SINR) and receiver performance by suppression or cancellation of interference signal from inter-cells. In this paper, we propose the advanced receiver based on soft decision to reduce the interference from neighbor cell in LTE-Advanced downlink system. The proposed receiver can suppress and cancel the interference by calculating the unbiased estimation value of interference signal using minimum mean square error (MMSE) or interference rejection combing (IRC) receiver. The interference signal is updated using soft information expressed by log-likelihood ratio (LLR). We perform the system level simulation based on 20MHz bandwidth of 3GPP LTE-Advanced downlink system. Simulation results show that the proposed receiver can improve SINR, throughput, and spectral efficiency of conventional system.

• Journal of the Korean Institute of Landscape Architecture
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• v.51 no.1
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• pp.56-71
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• 2023

Citizens' needs for urban green spaces are on the rise due to improved quality of life and increased interest in environments. The garden is noteworthy because it is small in size, making it less controversial to create in the city, and it is adjacent to the residential area, improving citizens' daily environment. Moreover, recently gardens is attracting attention as a tool for urban regeneration, such as being created in declining areas as part of a government project. Therefore, it is time to study the role and value of urban gardens in deteriorated areas in terms of space welfare. However, there are few studies that quantitatively evaluate the effects of gardens, and many prior studies are limited to focusing the green space larger than a certain size (e.g., parks and forests). Therefore, the aim of this study is to examine the effect of garden and gardening quantitatively, paying attention to social aspects such as life satisfaction and community of inhabitants. The study was conducted in an old row housing complex in Gojan1-dong, Ansan-si, Gyeonggi-do. In there, some of the dwellers voluntarily created outdoor gardens and engaged in gardening for a long time. In addition, after the 2017 Gyeonggi-do Garden Fair, several gardens have been maintained and used by residents there. For the first step, the field trip was done to research the status of the garden in the area, and then, a survey was conducted on whether or not gardening has an impact on the life satisfaction and community of residents. The results were analyzed by t-test and ANOVA. As a result, residents who are engaged in gardening are more active in the "neighborhood exchange" and "resident participation" than those who are not engaged in gardening. In addition, if residents voluntarily create a garden, the level of "satisfaction of life" is higher than those staying in the garden which is constructed by the government. And a resident who is gardening in the complex shows higher life satisfaction than those who garden outside of the complex. These results confirmed that the garden has positive effects promoting "exchanges with neighbors", "participation in the community", and "life satisfaction" of residents. It shows that it is important to ensure the right of residents to participate in the garden-making process as much as possible, and the garden's location should be paid attention to maximize the positive effect of gardens.