• Journal of Korea Spatial Information System Society
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• v.11 no.3
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• pp.55-62
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• 2009

Location based Services in the ubiquitous computing environment, namely u-LBS, use very large and skewed spatial objects that are closely related to locational information. It is especially essential to achieve fast search, which is looking for POI(Point of Interest) related to the location of users. This paper examines how to search large and skewed POI efficiently in the u-LBS environment. We propose the Dynamic-level Grid based R-Tree(DGR-Tree), which is an index for point data that can reduce the cost of stationary POI search. DGR-Tree uses both R-Tree as a primary index and Dynamic-level Grid as a secondary index. DGR-Tree is optimized to be suitable for point data and solves the overlapping problem among leaf nodes. Dynamic-level Grid of DGR-Tree is created dynamically according to the density of POI. Each cell in Dynamic-level Grid has a leaf node pointer for direct access with the leaf node of the primary index. Therefore, the index access performance is improved greatly by accessing the leaf node directly through Dynamic-level Grid. We also propose a K-Nearest Neighbor(KNN) algorithm for DGR-Tree, which utilizes Dynamic-level Grid for fast access to candidate cells. The KNN algorithm for DGR-Tree provides the mechanism, which can access directly to cells enclosing given query point and adjacent cells without tree traversal. The KNN algorithm minimizes sorting cost about candidate lists with minimum distance and provides NEB(Non Extensible Boundary), which need not consider the extension of candidate nodes for KNN search.

• Journal of Korean Foot and Ankle Society
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• v.15 no.4
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• pp.232-239
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• 2011

Purpose: Diabetic foot ulcer is one of the most important diabetic complications because it increases the risk of amputations. Moreover, it lowers the quality of patients' life and increases the social medical expenses. Authors analyzed risk factors of intractable diabetic foot ulcer using retrospective study. Materials and Methods: From January 2007 to December 2010, 40 patients who could not achieve complete healing despite more than 12 weeks of proper management among who had been diagnosed and treated as diabetic foot ulcer at our hospital were included and evaluated retrospectively. We compared the risk factors between two groups who were finally treated by amputation and non-amputation. Results: The sample was composed of 31 male patients (77.5%) and 9 female patients (22.5%). Comorbidity including hypertension and hyperlipidemia were 77.5% and 80% each. By Wagner classification, 30 patients (80%) had ulcerative lesion over the grade 3. From bacteriology results, 29 patients (72.5%) had polybacteria infection. 35 patients (87.5%) had neuropathy and 26 patients (65%) had vascular stenosis at least one level. The mean initial ankle-brachial index and toe-brachial index were 0.982 and 0.439. In comparison between amputation group and non-amputation group, ulcer severity, number of stenotic vessel and initial ankle-brachial index/toe-brachial index had statistical significance. Conclusion: The most commonly risk factor of intractable diabetic foot ulcer was peripheral neuropathy reaching 87.5% of cases. In comparison with non-amputation group, ulcer severity according to Wagner classification, number of stenotic vessel and initial ankle-brachial index/toe-brachial index were demonstrated as a risk factor of amputation in intractable diabetic foot ulcer.

• Journal of Preventive Medicine and Public Health
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• v.46 no.5
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• pp.237-248
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• 2013

Objectives: The purpose of this study is to examine and explain the extent of income-related inequity in health care utilization and expenditures to compare the extent in 2005 and 2010 in Korea. Methods: We employed the concentration indices and the horizontal inequity index proposed by Wagstaff and van Doorslaer based on one- and two-part models. This study was conducted using data from the 2005 and 2010 Korean National Health and Nutrition Examination Survey. We examined health care utilization and expenditures for different types of health care providers, including health centers, physician clinics, hospitals, general hospitals, dental care, and licensed traditional medical practitioners. Results: The results show the equitable distribution of overall health care utilization with pro-poor tendencies and modest pro-rich inequity in the amount of medical expenditures in 2010. For the decomposition analysis, non-need variables such as income, education, private insurance, and occupational status have contributed considerably to pro-rich inequality in health care over the period between 2005 and 2010. Conclusions: We found that health care utilization in Korea in 2010 was fairly equitable, but the poor still have some barriers to accessing primary care and continuing to receive medical care.

• The Journal of Society for e-Business Studies
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• v.21 no.4
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• pp.15-28
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• 2016

As the industry of Mobile Internet has been gradually developed, the major device for accessing the web is predicted to shift from PC to Mobile devices in the near future. This drastic increase of demand in Mobile devices has drawn a more convenient standard of living by transcending time and space in our lives, however, it triggered various side effects such as a digital divide. This study was conducted to analyze how people utilize the contents via Mobile devices and their active attitude toward Mobile Internet by dividing individual characteristics into generations, education level and income level, and also identify whether Mobile contents utilization has an effect on the active attitude. The research results could be used for establishing a policy to narrow the gap in Mobile contents use and active attitude by individual characteristics.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.545-550
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• 2001

Domestic construction industry has faced with many problems in productivity, quality, safety and skilled-labor availability because of the national economic depression, insufficient supply of skilled labors and so on. There is a growing need for improving productivity and quality, and savings in cost. In the case of advanced countries, they have made a number of research efforts to solve these problems with construction automation and robotics. Recently, there are growing interests in construction automation and robotics but such interests have not been further increased due to the difficulties in gathering or accessing valuable information on the research and development of construction automation and robotics. The main purpose of this study is to provide a web-based research database and decision support system for an effective research and development of automated construction system and robots. It is expected that this system would be able to provide a framework for the successful research, development and implementation of the construction automation and robotics in domestic construction industry

• Journal of KIISE:Databases
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• v.29 no.4
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• pp.262-273
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• 2002

MOLAP is a technology that accelerates multidimensional data analysis by storing data in a multidimensional array and accessing them using their position information. Depending on a mapping scheme of a multidimensional array onto disk, the sliced of MOLAP operations such as slice and dice varies significantly. [1] proposed a MOLAP cube storage scheme that divides a cube into small chunks with equal side length, compresses sparse chunks, and stores the chunks in row-major order of their chunk indexes. This type of cube storage scheme gives a fair chance to all dimensions of the input data. Here, we developed a variant of their cube storage scheme by placing chunks in a different order. Our scheme accelerates slice and dice operations by aligning chunks to physical disk block boundaries and clustering neighboring chunks. Z-indexing is used for chunk clustering. The efficiency of the proposed scheme is evaluated through experiments. We showed that the proposed scheme is efficient for 3~5 dimensional cubes that are frequently used to analyze business data.

• Journal of KIISE:Databases
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• v.32 no.4
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• pp.345-361
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• 2005

A transform-space index indexes objects represented as points in the transform space An advantage of a transform-space index is that optimization of join algorithms using these indexes becomes relatively simple. However, the disadvantage is that these algorithms cannot be applied to original-space indexes such as the R-tree. As a way of overcoming this disadvantages, the authors earlier proposed the transform-space view join algorithm that joins two original- space indexes in the transform space through the notion of the transform-space view. A transform-space view is a virtual transform-space index that allows us to perform join in the transform space using original-space indexes. In a transform-space view join algorithm, the order of accessing disk pages -for which various space filling curves could be used -makes a significant impact on the performance of joins. In this paper, we Propose a new space filling curve called the adaptive row major order (ARM order). The ARM order adaptively controls the order of accessing pages and significantly reduces the one-pass buffer size (the minimum buffer size required for guaranteeing one disk access per page) and the number of disk accesses for a given buffer size. Through analysis and experiments, we verify the excellence of the ARM order when used with the transform-space view join. The transform-space view join with the ARM order always outperforms existing ones in terms of both measures used: the one-pass buffer size and the number of disk accesses for a given buffer size. Compared to other conventional space filling curves used with the transform-space view join, it reduces the one-pass buffer size by up to 21.3 times and the number of disk accesses by up to $74.6\%$. In addition, compared to existing spatial join algorithms that use R-trees in the original space, it reduces the one-pass buffer size by up to 15.7 times and the number of disk accesses by up to $65.3\%$.

• The KIPS Transactions:PartD
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• v.15D no.4
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• pp.451-462
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• 2008

Recently, with the advent of applications using locations of moving objects, it becomes crucial to develop efficient index schemes for spatio-temporal databases. The $TPR^*$-tree is most popularly accepted as an index structure for processing future-time queries. In the $TPR^*$-tree, the future locations of moving objects are predicted based on the CBR(Conservative Bounding Rectangle). Since the areas predicted from CBRs tend to grow rapidly over time, CBRs thus enlarged lead to serious performance degradation in query processing. Against the problem, we propose a new method to adjust CBRs to be tight, thereby improving the performance of query processing. Our method examines whether the adjustment of a CBR is necessary when accessing a leaf node for processing a user query. Thus, it does not incur extra disk I/Os in this examination. Also, in order to make a correct decision, we devise a cost model that considers both the I/O overhead for the CBR adjustment and the performance gain in the future-time owing to the CBR adjustment. With the cost model, we can prevent unusual expansions of BRs even when updates on nodes are infrequent and also avoid unnecessary execution of the CBR adjustment. For performance evaluation, we conducted a variety of experiments. The results show that our method improves the performance of the original $TPR^*$-tree significantly.

• Journal of Korea Spatial Information System Society
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• v.6 no.2 s.12
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• pp.23-37
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• 2004

Location Based Services(LBSs) in mobile environments become very popular recently. For efficient LBSs, spatial database management systems must need a spatial indexing scheme such as R-trees in order to manage the huge spatial database. However, it may need unnecessary disk accesses since it needs to access objects which are not actually concerned to user's location-based queries. In this paper, to support the location-based queries efficiently, we propose a CLR-tree(Cell Leveling R-tree) in which a dynamic cell is built up within the minimum bounding rectangle of R-trees' node. The cell level of nodes is compared with the query's cell level in location-based query processing and determines the minimum search space. Also, we propose the insertion, split, deletion, and search algorithms for CRL-trees. From the experimental results, we see that a CLR-tree is able to decrease $5{\sim}20%$ of disk accesses from those of R-trees. So, a CLR-tree can be used for fast accessing spatial objects to user's location-based queries in LBSs.

• Journal of Digital Convergence
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• v.16 no.1
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• pp.13-20
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• 2018

The regional differences between urban and rural areas make many diverse differences. There are various differences between urban and rural areas such as economic gap and cultural gap. There is also a difference between urban and rural areas in accessing and utilizing information. The purpose of this study is to clarify the relationship between the information gap and the income gap among farmers and fishermen groups, where information gap is considered to be more serious than other groups. In other words, we tried to examine whether the information gap between farmers and peasants affects the income gap. The purpose of this study is to analyze the relationship between informatization level and income of farmers based on the information gap index and survey results conducted every year by the government. The results show that there is a statistically significant positive relationship between the informatization level of farmers and household income. In addition, the trend of the regression coefficient is positive, suggesting that the government needs various informatization policies to increase the informatization level of farmers.