• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.11
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• pp.1615-1622
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• 2022

In order to overcome the limitations of the instructor-centered lecture-style teaching method, recently, flipped learning, a learner-centered teaching method, has been widely introduced. However, despite the many advantages of flipped learning, there is a problem that students cannot solve questions that arise during prior learning in real time. Therefore, in order to solve this problem, we developed DBbot, an assistant chatbot for database design course managed in the flipped learning method. The DBBot is composed of a chatbot app for learners and a chatbot management app for instructors. Also, it's implemented so that questions that instructors can anticipate in advance, such as questions related to class operation and every semester repeated questions related to learning content, can be answered using Google's DialogFlow. It's implemented so that questions that the instructor cannot predict in advance, such as questions related to team projects, can be answered using the question/answer DB and the BM25 algorithm, which is a similarity comparison algorithm.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.05a
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• pp.818-821
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• 2008

최근 위치기반 서비스 기술의 발달로 다양한 위치정보를 활용한 다양한 서비스가 제공되고 있다. 모블로그(Moblog) 서비스는 이러한 위치기반 서비스의 하나로써 모바일 사용자가 위치한 영역에 글을 포스팅하고 검색할 수 있는 서비스이다. 그러나 모블로그 서비스에서는 지역이 시스템에 의해서 임의로 나뉘어져 있기 때문에, 사용자가 동적으로 서비스 영역을 구분할 수 없고 세부적인 검색을 할 수 없다는 단점이 있다. 본 논문에서는 모바일 사용자가 현 위치에서 메모를 하거나 사진을 저장할 수 있는 가상게시판 서비스를 제안하고 구현하였다. 저장된 정보는 시스템의 공간 데이터로써 저장되어 사용자가 복합질의를 통하여 간편하게 검색할 수 있도록 하였다.

• The KIPS Transactions:PartD
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• v.19D no.2
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• pp.133-138
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• 2012

Queries entered in a search box are the results of users' activities to actively seek information. Therefore, search logs are important data which represent users' information needs. The purpose of this study is to examine if there is a relationship between the results of queries automatically classified and the categories of documents accessed. Search sessions were identified in 2009 NDSL(National Discovery for Science Leaders) log dataset of KISTI (Korea Institute of Science and Technology Information). Queries and items used were extracted by session. The queries were processed using an automatic classifier. The identified queries were then compared with the subject categories of items used. As a result, it was found that the average similarity was 58.8% for the automatic classification of the top 100 queries. Interestingly, this result is a numerical value lower than 76.8%, the result of search evaluated by experts. The reason for this difference explains that the terms used as queries are newly emerging as those of concern in other fields of research.

• Journal of Digital Contents Society
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• v.18 no.8
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• pp.1561-1566
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• 2017

Due to the advances in machine learning and artificial intelligence technologies, many new services have become available. Among such services, recommendation systems have already been successfully applied to commercial services and made profits as in online shopping malls. Most recommendation algorithms in commercial services are based on content analysis or explicit feedback rates as in movie recommendations. However, many online shopping malls have difficulties in content analysis or are lacking explicit feedbacks on their items, which results in no recommendation system for their items. Even for such service systems, user log data is easily available, and if recommendations are possible with such log data, the quality of their service can be improved. In this paper, we extract implicit feedback like click information for items from log data and provide a recommendation system based on the implicit feedback. The proposed system is applied to a real in-service online shopping mall.

• Journal of KIISE:Databases
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• v.32 no.5
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• pp.558-566
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• 2005

The XML is the new standard fir data representation and exchange on the Internet. In this paper, we describe a new approach for evaluating a path-oriented query against XML document. In our approach, we propose the Parallel Match Indexing Fabric to speed up evaluation of path-oriented query using path signature and design the parallel match algorithm to perform a match process between a path signature of input query and path signatures of elements stored in the database. To construct a structure of the parallel match indexing, we first make the binary tie for all path signatures on an XML document and then which trie is transformed to the Parallel Match Indexing Fabric. Also we use the Parallel Match Indexing Fabric and a parallel match algorithm for executing a search operation of a path-oriented query. In our proposed approach, Time complexity of the algorithm is proportional to the logarithm of the number of path signatures in the XML document.

• Korean Journal of Ecology and Environment
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• v.36 no.3 s.104
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• pp.336-343
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• 2003

Two types of statistical models, simple and multivariate log linear models, were studied for continuity simulation and trend analysis of water qualities in incoming flows to Lake Paldang. Water quality is a function of one independent variable (flow) in the simple log linear model, and of three different variables (flow, time, and seasonal cycle) in multivariate model. The independent variables act as surrogate variables of water quality in both models. The model coefficients were determined by the monthly data. The water qualities included 5-day Biochemical Oxygen Demand ($BOD_5$), Total Nitrogen (TN), and Total Phosphorus (TP) measured from 1995 to 2000 in the South and the North branches of Han River and the Kyoungan Stream. The results indicated that the multivariate model provided better agreements with field measurements than the simple one in a31 attempted cases. Flow dependency, seasonality, and temporal trends of water quality were tested on the determined coefficients of the multivariate model. The test of flow dependency indicated that BOD concentrations decreased as the water flow increased. In TN and TP concentrations, however, there were no discernible flow effects. From the temporal trend analyses, the following results were obtained: 1) no trends on BOD at all three upstreams, 2) increase on TN at the South Branch and the Kyoungan Stream, 3)decrease on TN at the North Branch,4) no trends on TP at the North and the South Branches and 5) increase on TP at the Kyoungan Stream by 3 to 8% per years. The seasonality test showed that there were significant seasonal variations in all three water qualities at three incoming flows.

• Journal of the Korea Society of Computer and Information
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• v.11 no.6 s.44
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• pp.289-298
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• 2006

Many researches are going on with regard to issues and problems related to mobile database systems, which are caused by the weak connectivity of wireless networks, the mobility and the portability of mobile clients. Mobile computing satisfies user's demands for convenience and performance to use information at any time and in any place, but it has many problems to be solved in the aspect of data management. The purpose of our study is to design Mobile Continuous Query Processing System(MCQPS) to solve problems related to database hoarding, the maintenance of shared data consistency and the optimization of logging, which are caused by the weak connectivity and disconnection of wireless networks inherent in mobile database systems under mobile client server environments. We proved the superiority of the proposed MCQPS by comparing its performance to the C I S(Client-Intercept-Slaver) model. In Addition, we experiment on proposed index structure and methodology in various methods.

• The KIPS Transactions:PartD
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• v.12D no.4 s.100
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• pp.521-530
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• 2005

Many researches are going on with regard to issues and problems related to mobile database systems, which are caused by the weak connectivity of wireless networks, the mobility and the Portability of mobile clients. Mobile computing satisfies user's demands for convenience and Performance to use information at any time and in any Place, but it has many Problems to be solved in the aspect of data management. The purpose of our study is to design Mobile Query Processing System(MQPS) to solve problems related to database hoarding, the maintenance of shared data consistency and the optimization of logging, which are caused by the weak connectivity and disconnection of wireless networks inherent in mobile database systems under mobile client-server environments. In addition, we proved the superiority of the proposed MQPS by comparing its performance to the C-I-S(Client-Intercept- Server) model.

• 한국공간정보시스템학회:학술대회논문집
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• 2003.11a
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• pp.84-90
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• 2003

최근 이동 컴퓨팅 기술이 급속도로 발전하면서 이동 객체의 위치정보를 활용한 위치 찾기 서비스, 교통 정보 서비스, 긴급 구조 서비스, 모바일 광고 서비스와 같은 위치 기반 서비스가 부각되고 있다. 이와 같은 다양한 서비스를 제공하기 위해서는 이동 객체의 위치정보를 신속하게 저장, 검색, 갱신할 수 있는 이동 객체 데이타베이스 시스템이 필수적으로 요구된다. 그러나, 기존의 데이타베이스 시스템을 사용할 경우에는 저장 공간을 많이 차지게 되고, 불필요한 트랜잭션 연산으로 인하여 대용량의 위치 데이타 관리에 큰 오버헤드가 발생한다는 문제가 있다. 그러므로, 이동 객체의 위치 데이타를 저장하고 관리하기 위하여 화일 기반의 저장 시스템을 사용하는 것이 보다 더 효율적이다. 이에 본 논문에서는 대용량의 위치 데이타를 효과적으로 저장 및 검색할 수 있는 화일 기반 이동 객체 저장 컴포넌트를 설계하고 구현하였다. 화일 기반 이동 객체 저장 컴포넌트는 다중 연결 관리자, 단순 질의 처리기, 메타데이타 관리자, 데이타 화일 관리자, 인덱스 화일 관리자, 로그 관리자, 관리툴로 구성된다.

• The Transactions of the Korea Information Processing Society
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• v.1 no.1
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• pp.1-13
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• 1994

The Temporal Database Management Testbed supports valid and transaction time. In this paper, we discuss the design and implementation of a testbed of a temporal database management system in main memory. The testbed consists of a syntactic analyzer, a semantic analyzer, a code generator, and an interpreter. The syntactic analyzer builds a parse tree from a temporal query. The semantic analyzer then checks it for correctness against the system catalog. The code generator builds an execution tree termed ann update network. We employ an incremental view materialization for the execution tree. After building the execution tree, the interpreter activates each node of the execution tree. Also, the indexing structure and the concurrency control are discussed in the testbed.