• 한국정보과학회논문지:데이타베이스
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• 제27권2호
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• pp.175-184
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• 2000

데이타 웨어하우스는 외부 데이타를 통합 요약하여 저장하는 시스템으로, 의사 결정에 필요한 정보를 효과적으로 제공할 수 있다. 대부분의 데이타 웨어하우스에서는 데이타를 정랴한 결과를 형성(materialized) 뷰의 형태로 저장한다. 이 때 뷰가 정의된 데이타 소스가 변화하면 뷰는 이를 반영하기 위 해 갱신되어야 한다. 뷰에 대한 갱신 작업은 상당한 부하를 야기시킬 수 있으므로, 이러한 갱신 작업을 효율적으로 수행하는 것은 매우 중요한 문제가 된다. 이미 뷰의 효율적인 갱신 방법에 대해서는 많은 연구 가 이루어져 왔다. 그러나 뷰가 여러 개의 데이타 소스에 의해 정의되고 이들 중 둘 이상의 데이타 소스가 변화된 경우, 이를 뷰에 반영하기 위해서 기존의 방법들은 데이타 소스에 대해 많은 수의 접근이 이루어져야 한다. 본 논문에서는 여러 개의 데이타 소스에 변화가 일어난 경우, 기존 연구에 비해 데이타 소스에 대한 접근을 줄일 수 있는 효율적인 뷰 갱신 방법을 제안한다 . 그리고 TPC-D 데이타를 사용한 실험을 통하여 본 논문에서 제안한 방법이 기존의 방법들보다 성능이 우수하다는 것을 보인다.

• 한국전자거래학회지
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• 제14권1호
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• pp.143-160
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• 2009

대용량의 데이타를 다루는 OLAP 데이타베이스 환경에서는 기반 디스크 시스템의 구조와 효율적 접근방법이 전체적인 성능을 좌우하는 중요한 요소가 된다. 최근 들어 하드 디스크들은 여러 개의 물리적 존을 갖는 구조로 설계되고 있는데, 각 존들은 그 위치에 따라 다양한 탐색시간과 데이타 전송률을 갖는 특징을 갖고 있다. 그러나 기존 연구에서는 다중 존을 고려하지 않은 하나의 탐색시간과 데이타 전송률을 갖는 단순한 디스크 모델에 기반을 두고 진행되어 왔다. 본 논문에서는 대용량의 데이타를 다루는 OLAP 환경에서 주어진 실체뷰 집합을 다중 존에 효율적으로 저장하는 기법을 제안한다. 이를 위해 각 실체뷰를 접근확률에 따라 디스크 존에 배치하는 알고리즘을 제시하고, 데이타 지속적으로 갱신되는 동적 환경에서의 저장 방법에 대해서도 살펴본다. 마지막으로 실험을 통하여 본 논문에서 제시된 알고리즘을 효율성을 증명한다.

• 건축역사연구
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• 제12권4호
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• pp.27-48
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• 2003

This paper aims to identify the meaning of architectural form of the East and the West. Ordinarily, we know the visual differences of architectural form between the two cultural families, and the technical reasons of such differences. However, the East and the West have their own views of architectural form that are derived from their own views of architecture, and again the views of architecture are rooted in their own views of the world. The paper maintains a comparative stance between the two cultures in analyzing the different concepts of architectural form, and employ the ideas of 'Form(形象)' and 'Energy-Form(氣形)' as a kind of representative concept of the two views of architectural form. It is discussed that the idea of Form pursued the realization of ultimate substance which is less materialistic but more ideal., while, the idea of Energy-Form pursued the realization of oneness and health through mutual interaction between man, architecture and nature. Architectural form in the West has been the purposeful expression of human ideal, while in the East, it was an expediential device for better energy condition. It seems important to understand such differences of the meaning of architectural form between the East and the West, since, in present time, we tend to think that the Western conception of architectural form is the only possible one. But it is not generally known that the Western conception of form has very particular background reason of its own which is unique to Western culture, and on the other hand, the nature of East Asian conception of architectural form is generally unknown.

• 한국과학교육학회지
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• 제39권6호
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• pp.791-797
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• 2019

이 연구에서는 2015 개정 과학과 교육과정에 의한 통합과학과 과학탐구실험이 학생들의 과학에 대한 흥미, 과학적 태도, STS와 NOS에 대한 견해에 미치는 영향을 조사하였다. 수도권 소재의 고등학교에 재학 중인 1학년 학생 223명이 연구에 참여하였으며, 통합과학과 과학탐구실험의 이수 전후에 각각 검사를 실시하고 두 검사의 결과를 비교하였다. 연구 결과, 과학에 대한 흥미 점수와 과학적 태도 점수는 이수 전후에 유의미하게 향상되었다. STS에 대한 견해의 점수를 분석한 결과, 연구 윤리에 관한 항목의 견해는 이수 후에 유의미하게 향상되었으나 나머지 항목에서는 유의미한 차이가 없었다. NOS에 대한 견해의 점수는 모든 영역에서 이수 전후에 유의미한 차이가 없었다. 이에 대한 교육적 함의를 논의하였고, 후속 연구를 제안하였다.

• 한국초등과학교육학회지:초등과학교육
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• 제30권2호
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• pp.189-203
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• 2011

The object of this study is to investigate the views of scientifically gifted children about the purpose of scientists' experiments and school science experiments. The children's views were examined using a open-ended questionnaire survey. And then the responses from the children were analyzed with categorization. The results from the study are as follows: First, the children's views about the purpose of scientists' experiments and school science experiments were classified to 2 top-level, 5 mid-level and 21 sub-level categories. Second, it was found that the children considered internal values of doing experiments are more worthy than the social and personal usefulness of the experiments. Third, the gifted children mentioned most frequently that the purposes of the scientist experiment is 'to get the evidences for their theory and argument which is unusual in the regular children's views. Also the discovery of new phenomena and materials, and the generation of new theories and ideas were mentioned as purposes of the scientist experiments. Fourth, the students frequently stated that school science experiments support effective learning of science subject enhancing subject interests and better explanation/understanding. Fifth, relatively many students thought that the purposes of school science experiments are different with those of scientist experiments. Based on the results from the study, some educational suggestions are discussed.

• 한국초등과학교육학회지:초등과학교육
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• 제29권3호
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• pp.262-276
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• 2010

The purpose of this study was to investigate and analyze the elementary teachers' views and students' views about the difficulties in teaching and learning on open inquiry activities of elementary school science. Semi-structured interviews were conducted individually with three elementary teachers who have serviced more than three years, and with twenty four elementary students attending schools located in Cheongju City. And their anecdotes were collected and analyzed. The interview questions were developed through Seidman's steps to acquire the reliability in the interview data. From the interviews and anecdotes, we found that elementary teachers' views about the difficulties of teaching open inquiry activities: the difficulties of teaching in finding inquiry problem and planning inquiry, the difficulties of managing group activities, the difficulties of managing class hours for inquiry, the lack of the students' inquiry abilities, and problems on students' affective characteristics. And the students have the views about the difficulties in doing open inquiry activities: the difficulties of finding inquiry problem and planning inquiry, being unaccustomed to write reports, the troubles with investigating, problems on affective characteristics, the difficulties of joining in a group, and the lack of inquiry abilities. The teachers give suggestions for effective application of the open inquiry activities: first, the teachers must encourage students' emotion and will in doing open inquiry activities, second, there must be the steady inquiry teaching and learning in ordinary elementary science classes. Based on the results, this study suggested that elementary teachers should concern specially about students' being unaccustomed to write reports and the troubles in doing scientific investigation.

• 한국과학교육학회지
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• 제17권4호
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• pp.395-403
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• 1997

In order to study the effect of the 'General Science' course implemented under the 6th science curriculum, high school students' views about the relationship between science/technology and society and their perceptions of science classroom environment were investigated. Four classes (n = 211) were selected from those completed the 'Science I' course under the 5th science curriculum, and 4 another classes (n = 216) which took the 'General Science' course under the 6th science curriculum were selected. In order to compare students' views about the relationship between science /technology and society. 10 items were selected from the VOSTS (Views On Science-Technology-Society) while considering the 6th science curriculum and the 'General Science' textbooks, and administered at the end of the 'Science I' course and at the beginning and end of the 'General Science' course. In order to compare the perceptions of science classroom environment, the Perceptions of Science Classroom Environment Questionnaire, which was prepared from the Individualized Classroom Environment Questionnaire. the Science Laboratory Environment Inventory, and the Classroom Environment Scale. was also administered at the end of the 'Science I' course and the 'General Science' course. The results indicated that the mean VOSTS score of the 6th-curriculum group was lower than that of the 5th-curriculum group, although the difference was not statistically significant. The decrease in the VOSTS score of the 6th-curriculum group during the 'General Science' course was statistically significant. It was also found that unrealistic views such as 'technology is the application of science', and 'corporations should control science/technology' had been formed during the course. However, the 6th-curriculum group had more positive perceptions of science classroom environment. Educational implications are discussed.

• Journal of Information Processing Systems
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• 제9권4호
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• pp.511-537
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• 2013

Numerous data intensive applications demand the efficient processing of a new type of query, which is called a progressive query (PQ). A PQ consists of a set of unpredictable but inter-related step-queries (SQ) that are specified by its user in a sequence of steps. A conventional DBMS was not designed to efficiently process such PQs. In our earlier work, we introduced a materialized view based approach for efficiently processing PQs, where the focus was on selecting promising views for materialization. The problem of how to efficiently find usable views from the materialized set in order to answer the SQs for a PQ remains open. In this paper, we present a new index technique, called the Dynamic Materialized View Index (DMVI), to rapidly discover usable views for answering a given SQ. The structure of the proposed index is a special ordered tree where the SQ domain tables are used as search keys and some bitmaps are kept at the leaf nodes for refined filtering. A two-level priority rule is adopted to order domain tables in the tree, which facilitates the efficient maintenance of the tree by taking into account the dynamic characteristics of various types of materialized views for PQs. The bitmap encoding methods and the strategies/algorithms to construct, search, and maintain the DMVI are suggested. The extensive experimental results demonstrate that our index technique is quite promising in improving the performance of the materialized view based query processing approach for PQs.

• 한국지구과학회지
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• 제29권7호
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• pp.602-616
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• 2008

본 연구의 목적은 글로벌 과학적 소양 함양을 위한 수업이 학생들의 과학의 본성에 대한 관점에 어떤 영향을 주는지 살펴보는 것이다. 연구 참여자는 8학년 65명의 남학생이며, '지구와 별' 단원에 대하여 5주 동안 글로벌 과학적 소양 수업을 실시하였다. 수업 전과 후에 학생들의 과학의 본성에 대한 이해정도를 살펴보았다. 연구 결과 단기간의 글로벌 과학적 소양 함양을 위한 수업으로 학생들의 과학의 본성에 대한 관점을 변화시키는 것은 어려운 과제임을 확인할 수 있었다. 그러나 사회학적 측면에서, 학생들의 과학의 본성에 대한 이해가 철학적, 심리학적, 역사학적 관점에서 보다 상대적으로 향상된 것을 발견할 수 있었다.

• 한국정보과학회논문지:데이타베이스
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• 제31권6호
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• pp.585-595
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• 2004

데이타 웨어하우스에서의 분석 질의는 대체로 복잡한 연산을 포함하고 있기 때문에 질의 처리 과정이 매우 중요하다. 성능 향상을 위해서 데이타 웨어하우스에서 보편적으로 쓰이고 있는 방법은 실체뷰를 구축하는 것이다. 어떤 실체뷰를 구축하느냐 하는 문제는 데이타 웨어하우스 전체의 질의처리 성능과 유지보수 비용에 중요한 영향을 미친다. 실체뷰 구성 문제란 이러한 질의처리 비용과 유지보수비용을 고려하여 최적의 실체뷰를 선택하는 것이다. 본 논문에서는 이러한 최적의 실체뷰를 구성하는 효율적인 해결방안을 제시한다. 최적 실체뷰의 구성문제는 일반적으로 NP-hard 문제이지만, 본 논문에서는 관계형 데이터 베이스에서 사용되는 조인, 선택, 그룹, 집계 연산의 특성을 고려하여 문제해결을 위한 탐색 공간을 획기적으로 줄이는 방법을 제안한다.