• Journal of Korean Society of Forest Science
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• v.83 no.3
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• pp.357-364
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• 1994

In this paper, the characteristics of cable logging systems, of which skyline length is adjustable during operation are discussed from a standpoint of system geometry. Among the cable logging systems, the live skyline is the typical one, of which operation is easy to understand. To analyze the cable logging mechanics of the live skyline, computer models were developed. In developing the computer models, the concept of the live skyline operation was classified into 'true live skyline' and 'live skyline with lift'. The former assumes to adjust skyline length continuously to maintain the skyline clearance over ground constant during inhaul ; the latter assumes to shorten the skyline length only to keep the minimum skyline clearance during inhaul. The computer model was used in investigating the mechanical efficiency and the operational characteristics of the live skyline system. First, the payload capability of live skyline was compared with that of standing skyline. Second, the effect of the change in the log-drag geometry on the payload capability of live skyline was investigated. Finally, the payload capability of live skyline with lift was compared with that of true live skyline as an effort to explain the concepts of true live skyline and live skyline with lift.

• Journal of Multimedia Information System
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• v.6 no.1
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• pp.37-42
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• 2019

Skyline queries are used in a variety of fields to make optimal decisions. However, as the volume of data and the dimension of the data increase, the number of skyline points increases with the amount of time it takes to discover them. Mainly, because the number of skylines is essential in many real-life applications, various studies have been proposed. However, previous researches have used the k-parameter methods such as top-k and k-means to discover representative skyline points (RSPs) from entire skyline point set, resulting in high query response time and reduced representativeness due to k dependency. To solve this problem, we propose a new Connected Component Clustering based Representative Skyline Query (3CRS) that can discover RSP quickly even in high-dimensional data through connected component clustering. 3CRS performs fast discovery and clustering of skylines through hash indexes and connected components and selects RSPs from each cluster. This paper proves the superiority of the proposed method by comparing it with representative skyline queries using k-means and DBSCAN with the real-world dataset.

• International Journal of Contents
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• v.6 no.1
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• pp.47-52
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• 2010

Skyline queries are an important new search capability for multi-dimensional databases. Most of the previous works have focused on processing skyline queries over static data set. However, most of the real applications deal with the dynamic data set. Since dynamic data set constantly changes as time passes, the continuous skyline computation over dynamic data set becomes ever more complicated. In this paper, we propose a multiple layer grids method for continuous skyline computation (MLGCS) that maintains multiple layer grids to manage the dynamic data set. The proposed method divides the work space into multiple layer grids and creates the skyline influence region in the grid of each layer. In the continuous environment, the continuous skyline queries are only handled when the updating data points are in the skyline influence region of each layer grid. Experiments based on various data distributions show that our proposed method outperforms the existing methods.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06b
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• pp.588-591
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• 2008

본 논문은 Data mining에서 선호도 분석 등에 사용되는 Skyline Query[2] 중 자료의 속성에 spatial한 성질이 있을 때 사용할 수 있는 Spatial Skyline Query[3] 문제에 대해 연구한다. 우선 Spatial Skyline 집합을 추출하기 위한 기존의 알고리즘의 문제점을 짚어보고 보다 개선된 알고리즘을 제시한다. 또한 전체 Spatial Skyline 집합이 아닌 그 중 더 의미 있을 수 있는 부분 집합을 좀 더 빠른 시간 복잡도에 구하는 방법 또한 제시한다.

• Journal of KIISE:Databases
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• v.37 no.1
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• pp.12-21
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• 2010

Recently, "Service of information perspective" that is an important issue is that a company searches customers that interested in certain information and the company offers information to the customers. This service can gain high effects by low cost because of supporting selective information. In most recently, Reverse Skyline using Skyline Approximation(RSSA) is proposed to process services of information provider's perspective. RSSA has problem to defects about waste of processing time and memory. In this paper, Efficient Reverse Skyline(ERSL) Algorithm is proposed for Efficient processing the Skyline. ERSL is new Algorithm using Branch and Bound Skyline(BBS) reduces the waste of processing time and memory. When we execute the variety experimentation to valuation ERSL algorithm's capacity. It is proved the best efficient algorithm among the others because ERSL is flexibly kept the established capacity.

• Architectural research
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• v.21 no.4
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• pp.91-98
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• 2019

In modern times, numerous cities are competing to create the unique skyline adjacent to the water. Tall buildings located across the river have a great contribution to the skyline of a riverfront city and can be a precious asset for the city. Moreover, in several cities, tall buildings and their impact on the urban skyline are a matter that should be considered and regulated in urban design. Therefore, as a prominent element in a larger visual setting of the city, tall buildings should improve the visual quality of the skyline rather than diminish that quality. This research attempts to provide an objective method to analyze the visual quality of the skyline made by a group of tall buildings through their feature of heights and spatial arrangement from riverfront views. The analysis is determined by the design variables of building heights variation, heights transition, density, and spacing of a group of tall buildings. A comparative case study of tall buildings in Yeouido and Lujiazui was conducted to prove the effectiveness of the analysis. The proposed method can be used in a simple way in the quantitative approach to quantify the visual quality of the skyline. In conclusion, Yeuido's skyline is not quite interesting from the riverfront view in terms of height variation and continuity of the skyline view because they are dispersed. Conversely, Lujiazui's skyline from the riverfront vantage points has a good quality in all aspects of the feature of height and spatial arrangements of tall buildings cluster. These factors can be used for the urban designer on how proposed tall buildings within the cluster should appropriately respond to adding image on the skyline.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.11 no.1
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• pp.39-51
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• 2008

These days, one of the issues well discussed is the obstruction or screen of sight to mountain-skyline by buildings. So question is to which heights buildings should be constructed over mountain-skyline and then harmony can be realized between mountain-skyline and building-outline. Based on the mentioned above, this study intends to find out the proper projection- level of buildings over background mountain-skyline when considering the types of mountain-skyline, building-outline and building-layout. The results of this study are first, the proper projection-ratio of buildings over background mountain-skyline can be 0.1 because assessment values on harmony-level are more than 3.0 in almost cases, second, the building-outline influences on the assessment values of harmony-level when the types of mountain-skyline are formed left-high & right-low and right-high & left-low, third, building-layout doesn't influence on the assessment va lues of harmony-level, finally, statistically difference doesn't exist between expert group and non-expert group in the assessment values of harmony-level.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.7
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• pp.809-813
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• 2010

Many studies on reverse skyline query processing have been done for company oriented services. The existing methods about reverse skyline are reverse skyline based on dynamic skyline. There is no reverse skyline query processing algorithm based on metric spaces for location-based services. In this paper we propose a reverse skyline query processing scheme that applies for a general skyline and considers distance spaces. The proposed method processes reverse skyline queries in the metric spaces using the existing spatial indexing scheme and considers both Monochromatic and Bichromatic environments. In order to show the superiority of the proposed scheme, we compare it with the basic skyline query processing scheme through performance evaluation. As a result, the proposed method excellent performance was about 5000 times more than conventional method.

• The KIPS Transactions:PartD
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• v.17D no.1
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• pp.17-24
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• 2010

Recently, there has been growing interest in skyline queries. Most of works for skyline queries assume that the data do not have null value. However, when we input data through the Web or with other different tools, there exist incomplete data with null values. As a result, several skyline processing techniques for incomplete data have been proposed. However, available skyline query techniques for incomplete data do not consider the environments that coexist complete data and incomplete data since these techniques deal with the incomplete data only. In this paper, we propose a novel skyline group processing technique which evaluates skyline queries for the environments that coexist complete data and incomplete data. To do this, we introduce the top-k(g) skyline group query which searches g skyline groups with respect to the user's dimensional preference. In our experimental study, we show efficiency of our proposed technique.

• Journal of KIISE:Databases
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• v.37 no.5
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• pp.250-257
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• 2010

As the variant of skyline query processing, reverse skyline Queries have been studied. However, the existing methods for processing reverse skyline Queries have the limitation of service domains and spend high costs to provide various location-based services. In this paper, we propose a new reverse skyline Query processing method that efficiently processes a query with the objects in metric spaces. In addition, the proposed method also processes continuous reverse skyline queries efficiently. In order to show the superiority of the proposed scheme, we compare it with the previous reverse skyline 벼ery processing scheme in various environments. As a result, the proposed method achieves better performance than the existing method.