• Journal of KIISE:Computer Systems and Theory
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• v.31 no.3_4
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• pp.145-151
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• 2004

We present an efficient data structure to obtain the range minima in an away in constant time. Recently, suffix ways are extensively used to search DNA sequences fast in bioinformatics. In constructing suffix arrays, solving the range minima problem is necessary When we construct suffix arrays, we should solve the range minima problem not only in a time-efficient way but also in a space-efficient way. The reason is that DNA sequences consist of millions or billions of bases. Until now, the most efficient data structure to find the range minima in an way in constant time is based on the method that converts the range minima problem in an array into the LCA (Lowest Common Ancestor) problem in a Cartesian tree and then converts the LCA problem into the range minima problem in a specific array. This data structure occupies O( n) space and is constructed in O(n) time. However since this data structure includes intermediate data structures required to convert the range minima problem in an array into other problems, it requires large space (=13n) and much time. Our data structure is based on the method that directly solves the range minima problem. Thus, our data structure requires small space (=5n) and less time in practice. As a matter of course, our data structure requires O(n) time and space theoretically.

• Journal of the Korean Geographical Society
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• v.46 no.4
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• pp.534-553
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• 2011

Analogical thinking is a problem-solving strategy to use a familiar problem (or base analog) to solve a novel problem of the same type (the target problem). The purpose of this study is to provide new insight into geography teaching and learning by connecting cognitive science research on analogical thinking with issues of geography education and suggest that teaching with analogies can be a productive instructional strategy for geography. In this study, using the various examples of analogical thinking used in geography we defined analogical thinking, addressed the theoretical models on analogical transfer, and discussed conditions that make an effective analogical transfer. The major research findings include the following: a) the spatial analogy, indicating skills to find places that may be far apart but have similar locations, and therefore have other similar conditions and/or connections, can provide a useful way to design contents for place learning; b) representational transfer, specifying a common representation for two problems, can play a key role in solving geographic problems requiring data visualization and spatialization processes; and c) either asking learners to compare/analyze similar examples sharing common structure or providing them examples bridging the gap between concrete, real-life phenomena and the ideas and models can contribute to learning in geographic concepts and skills. The spatial analogy requiring both geographic content knowledge and visual/spatial thinking has the potential to become a content-specific problem-solving strategy. We ended with recommendations for future research on analogy that is important in geography education.

• 월간 기계설비
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• s.232
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• pp.32-32
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• 2009

도시가스사업법 시행규칙 개정(09.09.26)에 따라 가스계량기를 대피공간에 설치하지 못하도록 함에 있어 기 시공되고 있는 대피공간 설치에 따른 문제를 다음과 같이 질의하여 안내하오니 업무에 참고하시기 바랍니다.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.11a
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• pp.212-213
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• 2002

급속한 도시화와 인구 고밀도화에 따라 수반되는 교통문제와 생활공간의 확보는 대부분의 대도시가 직면한 사회적 문제이다. 특히 교통문제 해결을 위해 서울시가 추진하고 있는 지하철 건설은 밀집화 된 도시의 공간활용 측면에 있어서 필연적이라고 할 수 있다. 서울시 지하철은 40% 이상의 높은 수송 분담율을 기록하고 있다. 그러나 양적인 증가에 반해, 공간적인 밀폐성 증가로 인한 대기질, 소음·진동 환경 의한 시민들의 건강 위해성 악화가 논란의 대상이 되고 있다. (중략)

• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.586-588
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• 2001

회로분할 기법은 VLSI 설계뿐만 아니라 많은 분야에서 응용될 수 있어 오랫동안 연구가 행해졌다. 대부분의 회로분할 휴리스틱에서 Fiduccia-Mattheyses(FM) 방법을 핵심 기술로 사용하고 있다. 회로 분할 문제는 또한 다른 컴비네토리얼 문제에서처럼 해 공간에서 최적해를 찾는 문제로 볼 수 있는데. GWW(Go With the Winners) 방법은 해 공간을 검색하는 성공적인 패러다임 중의 하나이다. 본 논문에서는 “GWW” 패러다임을 FM 방법에 접목시켜 회로를 분할하기 위한 휴리스틱을 제안한다. MCNC 벤치마크 회로를 이용하여 전형적인 FM 방법에 의한 결과와 “GWW”패러다임을 접목하여 얻은 결과를 비교하였다. 실험결과는 매우 고무적이다.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2009.04a
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• pp.215-217
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• 2009

u-GIS는 기존 정적인 공간데이터와 동적인 GeoSensor 데이터를 융합하여 처리하는 시스템을 말한다. 기존 정적인 공간 데이터는 주로 2차원 공간 데이터였으며 최근 유비쿼터스 환경에서는 이를 확장한 3차원 공간 데이터 및 다차원 시공간 데이터의 요구가 급증하고 있다. 최근 국가 차원에서 3차원 공간 데이터를 구축하고 있으며 DBMS가 아닌 파일 단위로 데이터를 저장하고 관리하고 있다. 이 경우, 데이터의 중복 저장, 표준 인터페이스의 부재, 서버 중심의 데이터 제공의 어려움 등의 문제가 발생한다. 따라서 본 연구에서는 3차원 공간데이터를 효과적으로 저장 관리하기 위하여 3차원 공간 DBMS를 연구 개발하였다.

• Journal of the Korea Society of Computer and Information
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• v.17 no.7
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• pp.87-95
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• 2012

In this paper, PTAS three-dimensional Steiner minimum tree connecting numerous input nodes rapidly in 3D space is proposed. Steiner minimum tree problem belongs to NP problem domain, and when properly devised heuristic introduces, it is generally superior to other algorithms as minimum spanning tree affiliated with P problem domain. But when the number of input nodes is very large, the problem requires excessive execution time. In this paper, a method using PTAS is proposed to solve the difficulty. In experiments for 70,000 input nodes in 3D space, the tree produced by the proposed 8 space partitioned PTAS method reduced 86.88% execution time, compared with the tree by naive 3D steiner minimum tree method, though increased 0.81% tree length. This affirms the proposed method can work well for applications that many nodes of three dimensions are need to connect swifty, enduring slight increase of tree length.

• Journal of the Korean Society of Safety
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• v.21 no.2 s.74
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• pp.143-149
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• 2006

This paper deals with the space-time finite element analysis of two-dimensional vibration problem with a single variable. The method of space-time finite elements enables the simpler solution than the usual finite element analysis with discretization in space only. We present a discretization technique in which finite element approximations are used in time and space simultaneously for a relatively large time period. The weighted residual process is used to formulate a finite element method for a space-time domain. A stability problem is described and some investigations for chosen type of rectangular space-time finite elements are carried out. Instability is caused by a too large time step of successive time steps in the traditional time-dependent problems. It has been shown that the numerical stability of time-stepping on the larger time steps is quite good. The unstructured space-time finite element not only overcomes the shortcomings of the stability in the traditional numerical methods, but it is also endowed with the features of an effective computational technique. Some numerical examples have been presented to illustrate the efficiency of the described method.

• Journal of the Korean Association of Geographic Information Studies
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• v.25 no.1
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• pp.120-132
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• 2022

Recently, the rapid increase in vacant houses in urban areas has caused various problems such as worsening urban landscape, causing safety accidents, crime accidents, and hygiene problems. According to the Statistics Korea Future Population Estimation results, the growth rate of Korean population and households is expected to continue to decrease, which is likely to lead to an increase in the occurrence of vacant houses. If the problem caused by the occurrence of vacant houses is neglected, it causes not only a physical decline such as a deterioration of the residential environment but also a social and economic decline. In order to solve this problem, it is necessary to grasp the spatial distribution characteristics of vacant houses at the local level considering the existence of regional characteristics and spatial influence. Therefore, in this study, in order to measure global spatial autocorrelation, the analysis was conducted centering on the old downtown area of Busan, where there are many vacant houses through Moran's I and Geographically Weighted Regression(GWR). In addition, the distribution of vacant houses in different spatial units in Eup_Myeon_Dong and Census was analyzed to evaluate the possibility of Modifiable Areal Unit Problem(MAUP), which differ in the results of spatial analysis as the spatial analysis units change. As a result of the analysis, the occurrence of vacant houses by Eup_Myeon_Dong in the old downtown area of Busan had spatial heterogeneity, and the spatial analysis results of vacant houses were different as the spatial analysis units were different. Accordingly, in order to understand the exact distribution characteristics of vacant house occurrence, spatial dimensions using the GWR model should be considered, and it is suggested that consideration of the MAUP is necessary.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1652-1657
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• 2009

종이지도, CAD 도면, 항공사진과 같은 형태로 구축되어 있는 저수지 퇴사자료는 자료의 훼손 변질 등에 대한 문제뿐만 아니라 자료관리를 위한 인력의 업무중복 및 시간부족에 따른 조사자료의 질의 저하 및 부정확성 문제 등 퇴사자료 관리에 있어 해결되어야 할 많은 문제점을 안고 있다. 이러한 문제점을 해결하기 위해 저수지 퇴사자료의 DB구축 및 자료관리방안 수립이 요구된다. 따라서 본 연구에서는 현재 구축되고 있는 항공사진과 같은 3차원 공간정보 DB구축으로 기존 자료와의 상호 활용성 미흡, 관련 사업의 연계성 부족 등의 문제점에 대처할 수 있는 체계적인 사업 추진방향을 제시하여 3차원 공간정보 DB구축 및 관리방안을 제시하였다. 이를 위해 본 연구에서는 저수지 퇴사자료 구축현황을 분석하고, 저수지퇴사 공간정보에 대한 구축방안을 수립하였으며, 구축된 공간정보의 효율적인 관리를 위한 저수지퇴사 공간정보 관리방안을 수립하였다. 이러한 공간정보 DB의 구축과 자료관리방안 수립으로 시 공간적 변화로 인한 저수지 퇴사를 쉽고 신속히 활용할 수 있는 공유기반 및 활용체계를 마련하게 되었으며, 효율적인 댐운영관리 및 수자원기초자료로도 활용할 수 있도록 하였다.