• Proceedings of the Korea Information Processing Society Conference
• /
• 2007.11a
• /
• pp.250-253
• /
• 2007

통신기술의 발달로 무선단말기의 보급이 급증하고 무선 네트워크 사용이 일반화됨으로써, 최근 유비쿼터스 컴퓨팅 기술이 중요한 이슈가 되고 있다. 유비쿼터스 컴퓨팅은 시간과 장소의 한계를 넘어 사용자가 하고자 하는 일을 컴퓨팅 환경이 상황을 인지하여 돕는 것을 가능하게 한다. 상황인지를 위해 순차패턴과 시간 연관규칙 탐사를 이용하여 사용자의 행동패턴을 추출하는 연구가 활발히 진행되고 있다. 이러한 연구를 통한 행동패턴은 사용자의 특성을 간과하게 되며, 각 사용자에게 더욱 유용한 서비스를 제공하기 위해서는 사용자를 분류하는 것이 필요하다. 그러나 기존의 연구는 단지 통계적인 사용자의 빈발 행동패턴만을 추출하여 각 사용자의 관심사와는 무관한 서비스 제공이 이루어질 수 있다. 성별, 나이, 직업 등의 개인정보와 위치를 고려하여 사용자에게 더욱 더 효율적이고 유용한 서비스를 제공할 수 있도록 행동패턴을 유형별로 분류할 필요가 있다. 본 논문에서는 각 위치에 따른 사용자의 연령대별 유용한 행동패턴을 추출하여 정확한 서비스를 제공할 수 있는 마이닝 기법을 제안한다.

• Proceedings of the Korean Society for Information Management Conference
• /
• 2001.08a
• /
• pp.213-218
• /
• 2001

본 연구는 육군대학 도서관 홈페이지의 웹서버에 저장되어 있는 로그파일을 실험 데이터로 사용하여, 기존 데이터마이닝(data mining)의 기법들 중에서 연관규칙(association rules) 탐사 기법을 적용함으로써, 사용자들의 웹 항행에 대한 순차패턴을 추출하였다. 이를 분석하여 실제 사용자들이 효과적으로 사용할 수 있는 웹사이트 디자인을 제안하고 나아가 대상 웹사이트의 사용편의성을 평가하였다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2000.04a
• /
• pp.40-44
• /
• 2000

최근의 네트워크를 통한 침입과 유형은 갈수록 다양화되고 있으며, 지능적으로 변하고 있다. 그러나 외부의 침입자뿐만 아니라 내부의 권한 오용으로 인한 침입의 탐지도 중요시되고 있으며, 그에 따른 운영체제와 네트워크 분야의 보안에 관한 연구 또한 활발히 진행되어 어느 정도의 성과를 얻고 있다. 그러나 데이터베이스의 보안은 데이터베이스 관리시스템에 거의 의존하고 있는 실정이다. 본 논문에서는 사용자의 정상행위를 효과적으로 모델링하기 위해서 데이터마이닝 기법인 연관규칙과 순차패턴을 이용하여 사용자의 정상행위 패턴을 추출하였다. 결과적으로 외부침입자 및 내부의 권한 오용자에 대한 비정상행위를 효과적으로 판정할 수 있다.

• Journal of Korea Spatial Information System Society
• /
• v.11 no.1
• /
• pp.127-136
• /
• 2009

This paper proposes an on-line mining algorithm of moving trajectory patterns in RFID data streams considering changing characteristics over time and constraints of single-pass data scan. Since RFID, sensor, and mobile network technology have been rapidly developed, many researchers have been recently focused on the study of real-time data gathering from real-world and mining the useful patterns from them. Previous researches for sequential patterns or moving trajectory patterns based on stream data have an extremely time-consum ing problem because of multi-pass database scan and tree traversal, and they also did not consider the time-changing characteristics of stream data. The proposed method preserves the sequential strength of 2-lengths frequent patterns in binary relationship table using the time-evolving graph to exactly reflect changes of RFID data stream from time to time. In addition, in order to solve the problem of the repetitive data scans, the proposed algorithm infers candidate k-lengths moving trajectory patterns beforehand at a time point t, and then extracts the patterns after screening the candidate patterns by only one-pass at a time point t+1. Through the experiment, the proposed method shows the superior performance in respect of time and space complexity than the Apriori-like method according as the reduction ratio of candidate sets is about 7 percent.

• The KIPS Transactions:PartD
• /
• v.9D no.3
• /
• pp.365-380
• /
• 2002

Temporal data mining, the incorporation of temporal semantics to existing data mining techniques, refers to a set of techniques for discovering implicit and useful temporal knowledge from large quantities of temporal data. Temporal knowledge, expressible in the form of rules, is knowledge with temporal semantics and relationships, such as cyclic pattern, calendric pattern, trends, etc. There are many examples of temporal data, including patient histories, purchaser histories, and web log that it can discover useful temporal knowledge from. Many studies on data mining have been pursued and some of them have involved issues of temporal data mining for discovering temporal knowledge from temporal data, such as sequential pattern, similar time sequence, cyclic and temporal association rules, etc. However, all of the works treated data in database at best as data series in chronological order and did not consider temporal semantics and temporal relationships containing data. In order to solve this problem, we propose a theoretical framework for temporal data mining. This paper surveys the work to date and explores the issues involved in temporal data mining. We then define a model for temporal data mining and suggest SQL-like mining language with ability to express the task of temporal mining and show architecture of temporal mining system.

• Proceedings of the Korean Information Science Society Conference
• /
• 2001.04b
• /
• pp.43-45
• /
• 2001

마이닝 시스템은 그 특성에 따라 매우 다른 형태의 구현 방법이 존재한다. 그러므로 마이닝 시스템간 호환성이나 재사용성은 매우 낮다. 본 노문에서는 이 문제를 시계열 데이터베이스를 통한 RDB와 강 결합함으로써 표준화에 대한 문제를 해겨라고자 시도하였다. RDB와의 강 결합은 표준화 문제를 해결함과 더불어 마이닝 시스템에 DBMS의 관련 기술을 이용함으로써 성능을 극대화시킨다. 특히 DBMS의 인텍스 기능을 이용함으로써 마이닝 시스템의 성능 향상을 시도하였다. 본 논문에서는 기존의 순차패턴 탐사의 시간개념 부재, 트랜잭션 데이터베이스 기반구조, 그리고 알고리즘 수행에 있어서 메모리 한계에 따른 문제등의 단점을 지적하고, 이를 수정하고 보완하기 위해서 시간 거리와 패턴 길이의 개념을 확장하였으며 그에 따른 연관규칙의 관련 공식을 수정 보완하여 제안한다. 또한 RDB와의 강 결합되어 기존의 트랜잭션 데이터베이스 구조를 벗어나 시계열 데이터에 보다 쉽게 적용할 수 있는 절차와 알고리즘을 제안한다.

• Journal of the Economic Geographical Society of Korea
• /
• v.10 no.1
• /
• pp.44-63
• /
• 2007

The purpose of this study is to propose mining processes in the large trip-transaction database of the Metropolitan Seoul area and to analyze the spatial characteristics of travel behavior. For the purpose. this study introduces a mining algorithm developed for exploring trip patterns from the large trip-transaction database produced every day by transit users in the Metropolitan Seoul area. The algorithm computes trip chains of transit users by using the bus routes and a graph of the subway stops in the Seoul subway network. We explore the transfer frequency of the transit users in their trip chains in a day transaction database of three different years. We find the number of transit users who transfer to other bus or subway is increasing yearly. From the trip chains of the large trip-transaction database, trip patterns are mined to analyze how transit users travel in the public transportation system. The mining algorithm is a kind of level-wise approaches to find frequent trip patterns. The resulting frequent patterns are illustrated to show top-ranked subway stations and bus stops in their supports. From the outputs, we explore the travel patterns of three different time zones in a day. We obtain sufficient differences in the spatial structures in the travel patterns of origin and destination depending on time zones. In order to examine the changes in the travel patterns along time, we apply the algorithm to one day data per year since 2004. The results are visualized by utilizing GIS, and then the spatial characteristics of travel patterns are analyzed. The spatial distribution of trip origins and destinations shows the sharp distinction among time zones.

• Journal of KIISE:Databases
• /
• v.28 no.3
• /
• pp.301-314
• /
• 2001

Data mining refers to a set of techniques for discovering implicit and useful knowledge from large database. Many studies on data mining have been pursued and some of them have involved issues of temporal data mining for discovering knowledge from temporal database, such as sequential pattern, similar time sequence, cyclic and temporal association rules, etc. However, all of the works treat problems for discovering temporal pattern from data which are stamped with time points and do not consider problems for discovering knowledge from temporal interval data. For example, there are many examples of temporal interval data that it can discover useful knowledge from. These include patient histories, purchaser histories, web log, and so on. Allen introduces relationships between intervals and operators for reasoning about relations between intervals. We present a new data mining technique that can discover temporal relation rules in temporal interval data by using the Allen's theory. In this paper, we present two new algorithms for discovering algorithm for generating temporal relation rules, discovers rules from temporal interval data. This technique can discover more useful knowledge in compared with conventional data mining techniques.

• Korean Journal of Remote Sensing
• /
• v.30 no.6
• /
• pp.731-742
• /
• 2014

In this study, we developed a new algorithm which can construct model buildings used as a surface boundary in numerical models using GIS with latitudinal and longitudinal information of building vertices. The algorithm established the outer boundary of a building first, by finding segments passing neighboring two vertices of the building and connecting the segments. Then, the algorithm determined the region inside the outer boundary as the building. The new algorithm overcame the limit that the algorithm developed in the previous study had in constructing concave buildings. In addition, the new algorithm successfully constructed a building with complicated shape. To investigate effects of the modification in building shape caused by the building-construction algorithm on flows and pollutant dispersion around buildings, a computational fluid dynamics model was used and three kinds of building type were considered. In the downwind region, patterns in flow and pollutant dispersion were little affected by the modification in building shape caused. However, because of reduction in air space resulted from the building-shape modification, vortex structure was not resolved or smaller vortex was resolved near the buildings. The changes in flow pattern affected dispersion patterns of scalar pollutants emitted around the buildings.

• Korean Journal of Remote Sensing
• /
• v.31 no.2
• /
• pp.149-160
• /
• 2015

A comparative study was conducted for alternative consecutive procedures of detection of cloud-contaminated pixels and gap-filling and smoothing of time-series data to produce high-quality gapless satellite vegetation index (i.e. Normalized Difference Vegetation Index, NDVI). Performances of five alternative methods for detecting cloud contaminations were tested with ground-observed cloudiness data. The data gap was filled with a simple linear interpolation and then, it was applied two alternative smoothing methods (i.e. Savitzky-Golay and Wavelet transform). Moderate resolution imaging spectroradiometer (MODIS) data were used in this study. Among the alternative cloud detection methods, a criterion of MODIS Band 3 reflectance over 10% showed best accuracy with an agreement rate of 85%, which was followed by criteria of MODIS Quality assessment (82%) and Band 3 reflectance over 20% (81%), respectively. In smoothing process, the Savitzky-Golay filter was better performed to retain original NDVI patterns than the wavelet transform. This study demonstrated an operational framework of gapdetection, filling, and smoothing to produce high-quality satellite vegetation index.