• The KIPS Transactions:PartD
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• v.19D no.1
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• pp.1-14
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• 2012

As the size of the data warehouse is large, the selection of indices on the data warehouse affects the efficiency of the query processing of the data warehouse. Indices induce the lower query processing cost, but they occupy the large storage areas and induce the index maintenance cost which are accompanied by database updates. The bitmap join indices are well applied when we optimize the star join queries which join a fact table and many dimension tables and the selection on dimension tables in data warehouses. Though the bitmap join indices with the binary representations induce the lower storage cost, the task to select the indexing attributes among the huge candidate attributes which are generated is difficult. The processes of index selection are to reduce the number of candidate attributes to be indexed and then select the indexing attributes. In this paper on bitmap join index selection problem we reduce the number of candidate attributes by the data mining techniques. Compared to the existing techniques which reduce the number of candidate attributes by the frequencies of attributes we consider the frequencies of attributes and the size of dimension tables and the size of the tuples of the dimension tables and the page size of disk. We use the mining of the frequent itemsets as mining techniques and reduce the great number of candidate attributes. We make the bitmap join indices which have the least costs and the least storage area adapted to storage constraints by using the cost functions applied to the bitmap join indices of the candidate attributes. We compare the existing techniques and ours and analyze them in order to evaluate the efficiencies of ours.

• Korea journal of population studies
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• v.29 no.3
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• pp.89-109
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• 2006

The 'Joongsancheung(JSC)', a unique term for the middle class in Korea, is defined as a stratum sharing common lifestyles and a certain level of life chances. It involves non-economic factors such as life chance, educational attainment, occupational groups as well as economic factor. Such objective measures as the occupational status of the main breadwinner, family income, and the educational level of respondent, and subjective measures of class identification are used for the operational definition of the JSC. Data from a national survey of 1,515 respondents is analyzed to investigate the change of the JSC in size and the major determinants of class identification. The results show that while there is no strong evidence of any significant change of the JSC by the objective measures during the recent decade, there seems to be a slight decrease in the subjective class identification. In addition, binary logistical regression analysis reveals that self-identification of JSC is heavily influenced by house ownership, along with subjective evaluation of one's own income and property ownership. This study demonstrates that the apparent class polarization in Korean society reflects not so much objective conditions but subjective perception of respondent of his or her circumstance. It is suggested that problems of housing and relative derivation people have as regards income and property should be resolved to alleviate such class polarization in Korean society.

• Journal of Gifted/Talented Education
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• v.25 no.6
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• pp.817-836
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• 2015

This research focuses on the development of gifted child behavior checklist which feasibly has application on the nation-wide gifted children observation-recommendation method. Corresponding measure has significance as it reflects actual observations of teachers teaching gifted children first-hand and involves measure of importance regarding each characteristic. An open survey on gifted children behavior characteristics lists and specific behavior patterns has been acquired from teachers in gifted education, and the checklist was developed through expert group review, pre-test, and confirmatory factor analysis process. The former checklists have shown several difficulties on application of observation-recommendation on the field due to behaviors that can't be observed in school, less important behaviors, and collide and duplicate behaviors etc. With regard to such problems, problematic clauses were removed based on the observation probability and importance of the behaviors. Ultimately, total of 32 behavior characteristic checklist consisting of ten sub factors(logical thinking, high achievement, originality, perfectionism, creative problem solving, curiosity, task commitment, conversation ability, creativity, passion) and two to three questions on each factor had been drawn. Through internal consistency test and item-total score correlation, each item of the measure has been analyzed to be consistently evaluating corresponding variables. In addition, the result of confirmatory factor analysis showed every item to be weighed appropriately on its sub-factor, strongly suggesting its feasibility on observation-recommendation of elementary gifted children as an appropriate checklist.

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.24-28
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• 2018

The redox flow battery (RFB) is a large-capacity energy storage equipment, and the vanadium redox flow cell is a typical RFB, but VRFB is expensive. Iron-chrome RFBs are economical because they use low-cost active materials, but their low performance is a urgent problem. In this study, the crossover of iron and chromium ion through Nafion membrane and the stability of Nafion membrane in HCl solution were investigated. The permeability of iron and chrome ion through Nafion were $5.5{\times}10^{-5}$ and $6.0{\times}10^{-5}cm^2/min$, respectively, which was 18.9~20.7 times higher than that of vanadium ion ($2.9{\times}10^{-6}cm^2/min$). The crossover of iron and chromium ions were shown to be a cause of performance decrease in Iron-chrome RFB. As the temperature increases, the crossover increases rapidly (activation energy 38.8 kJ/ mol), indicating that operation at low temperature is a methode to reduce the performance loss due to crossover. Nafion membranes were relatively stable in 3 M HCl solution.

• Journal of the Korean Institute of Gas
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• v.20 no.6
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• pp.23-30
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• 2016

The conventional natural gas engine realized lean combustion for the improved efficiency. However, in order to cope with exhaust gas regulations enforced gradually, the interest has shifted at the stoichiometric mixture combustion system. The stoichiometric mixture combustion method has the advantage of a three-way catalyst utilization whose purification efficiency is high, but the problem of thermal durability and the fuel economy remains as a challenge. Hydrogen-natural gas blend fuel (HCNG) can increase the rate of exhaust gas recirculation (EGR) because the hydrogen increases burning speed and lean flammability limit. The increase in the EGR rate can have a positive impact on heat resistance of the engine due to the decreased combustion temperature, and further can increase the compression ratio for efficient combustion. In this study, to minimize the exhaust emission developed HCNG engine with stoichiometric combustion method, developed three-way catalyst was applied to evaluate the conversion characteristics. The tests were carried out during the steady state and transient operating conditions, and the results were compared for both the conventional and proto-three-way catalyst of HCNG engine for city buses.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11c
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• pp.1529-1532
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• 2003

최근 인터넷과 모바일 시스템이 급속히 발달함에 따라 이를 통하여 지리정보와 같은 공간데이터를 제공하는 서비스가 증가하였다. 이는 대용량 데이터에 대한 관리 및 빠른 처리와 급증하는 사용자에 대한 높은 동시처리량 및 높은 안정성을 요구하였고, 이를 해결하기 위하여 비공유 공간 데이터베이스 클러스터가 개발되었다. 비공유 공간 데이터베이스 클러스터는 고가용성을 위한 구조로서 문제가 발생할 경우 다른 백업노드가 대신하여 서비스를 지속시킨다. 그러나 기존의 비공유 공간 데이터베이스 클러스터는 클러스터 구성에 대한 회복을 위하여 로그를 계속 유지하므로 로그를 남기기 위해 보통의 질의처리 성능이 저하되었으며 로그 유지를 위한 비용이 증가하였다. 또한 노드단위의 로그를 갖기 때문에 클러스터 구성에 대한 회복이 직렬적으로 이루어져 고가용성을 위한 빠른 회복이 불가능 하였다. 따라서 본 논문에서는 비공유 공간 데이터베이스 클러스터에서 고가용성을 위한 병렬 회복 기법을 제안한다. 이를 위해 클러스터 구성에 대한 회복을 위한 클러스터 로그를 정의한다. 정의된 클러스터 로그는 마스터 테이블이 존재하는 노드에서 그룹내 다른 노드가 정지된 것을 감지할 때 남기기 시작한다. 정지된 노드는 자체회복을 마친 후 클러스터 구성에 대한 회복을 하는 단계에서 존재하는 복제본 테이블 각각에 대한 클러스터 로그를 병렬적으로 받아 회복을 한다. 따라서 정지된 노드가 발생할 경우에만 클러스터 로그를 남기므로 보통의 질의처리의 성능 저하가 없고 클러스터 로그 유지 비용이 적으며, 클러스터 구성에 대한 회복시 테이블단위의 병렬적인 회복으로 대용량 데이터인 공간데이터에 대해 빠르게 회복할 수 있어 가용성을 향상시킨다.들을 문법으로 작성하였으며, PGS를 통해 생성된 어휘 정보를 가지고 스캐너를 구성하였으며, 파싱테이블을 가지고 파서를 설계하였다. 파서의 출력으로 AST가 생성되면 번역기는 AST를 탐색하면서 의미적으로 동등한 MSIL 코드를 생성하도록 시스템을 컴파일러 기법을 이용하여 모듈별로 구성하였다.적용하였다.n rate compared with conventional face recognition algorithms. 아니라 실내에서도 발생하고 있었다. 정량한 8개 화합물 각각과 총 휘발성 유기화합물의 스피어만 상관계수는 벤젠을 제외하고는 모두 유의하였다. 이중 톨루엔과 크실렌은 총 휘발성 유기화합물과 좋은 상관성 (톨루엔 0.76, 크실렌, 0.87)을 나타내었다. 이 연구는 톨루엔과 크실렌이 총 휘발성 유기화합물의 좋은 지표를 사용될 있고, 톨루엔, 에틸벤젠, 크실렌 등 많은 휘발성 유기화합물의 발생원은 실외뿐 아니라 실내에도 있음을 나타내고 있다.>10)의 $[^{18}F]F_2$를 얻었다. 결론: $^{18}O(p,n)^{18}F$ 핵반응을 이용하여 친전자성 방사성동위원소 $[^{18}F]F_2$를 생산하였다. 표적 챔버는 알루미늄으로 제작하였으며 본 연구에서 연구된 $[^{18}F]F_2$가스는 친핵성 치환반응으로 방사성동위원소를 도입하기 어려운 다양한 방사성의 약품개발에 유용하게 이용될 수 있을 것이다.었으나 움직임 보정 후 영상을 이용하여 비교한 경우, 결합능 변화가 선조체 영역에서 국한되어 나타나며 그 유의성이 움직임 보정 전에 비하여 낮음을 알 수 있었다. 결론: 뇌활성화 과제 수행시에 동반되는

• Journal of Science Education
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• v.35 no.1
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• pp.23-33
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• 2011

The purposes of this study were to analyze the effects on scientific creativity of the Science Gifted Program, to survey recognition of gifted learners on the Program, and to obtain implications for the development direction of guidance program. The subjects of this study were 20 persons of the class for the gifted in an elementary school science, which belonged to Education Institute for the Gifted, Office of Education in Jeju city. The Science Gifted Program were applied during 28 times. The effects of the program were analyzed using the scientific creativity test, recognition questionnaire and interview of the Science Gifted Program. The results of this study were as follows. First, after applying Science Gifted Program, the scientific creativity of the gifted in science was enhanced. Especially, fluency was enhanced most remarkably. Second, after applying Science Gifted Program, students stated that they had the positive feeling about this program. The suggestions of results of recognition questionnaire of the Science Gifted Program were as follows. First, the Science Gifted Program must include experiment and research of subject. Second, it is necessary to guide concretely of the learning method before beginning of the Science Gifted Program. Third, it is necessary to control content level and quantity of the task for the student's easy comprehension.

• Journal of the Korean Institute of Landscape Architecture
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• v.14 no.1
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• pp.33-43
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• 1986

Environmental designers in Korea have shown interests in Environomental Psychology and Behavior Studies (EPBS) since 1970's. However, many designers, who have expected a great deal of contribution from the EPBS, have disappointed due to their overexpectation and misunderstanding on the EPBS. This study intends to analyse the nature of the EPBS and to investigate the potential contribution of the EPBS to the field of environmental design. The EPBS are able to help designers by providing scentific data in each stage of the design process. Further, most design theories and principles are based on the findings of the EPBS. Thus the development of the EPBS has great potential of contribution to the development of design theories arid principles Due to the scientific nature of the EPBS, however, the EPBS have difficulties in supplying scientific data within relatively short period, which make most designers impatient. Designers should understand the scientific nature of the EPBS and be patient in expecting usable outcome from the EPBS. Further, Designers should not expect the EPBS give them design soultion itself.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.871-874
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• 2010

Needs for Smart Grid development are increasing all over the world as a solution to its problem according to depletion of energy resources, climatic and environmental rapidly change and growing demand for electrical power. Especially decentralized power is attracting world's attention. In this mood a new era for a unit scale of decentralized power environment is on its way in building. However there is a problem to have to be solved in the uniformity of power quality because the amount of power generated from renewable energy resources such as wind power and solar light is very sensitive to climate fluctuation. And thus this paper tries to suggest an energy management method on basis of real time monitoring for meteorological data. In the current situation of lacking in USN-based killer application in Smart Grid field, this paper proposes the USN-based DER management system which collects the meteorological data and control power system througout utilizing wireless sensor network technique this business. This communication technique is regarded to be efficient in aspects of installation cost and tits maintenance cost. The proposed EMS model embodies the method for predicting the power generation by monitoring and analyzing the climatic data and controling the efficient power distribution between the renewable energy and the existing power. The ultimate goal of this paper is to provide the technological basis for achieving zero-energy house.

• Resources Recycling
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• v.18 no.2
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• pp.3-15
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• 2009

To accomplish the greenhouse gas reduction which is over core unit project of the "Green growth" policy and "Resource circulation society", it is important to maintain proper balance and complement between energy recovery from waste and material recycling. This research(study) examined the related policies on the past of korea and foreign country, and also "The 4th resource recycling master plan" and "Energy recovery from waste plan" to provide advisable direction for resource recycling policy. The results of the research(study) showed that there were no significant difference between korea and developed foreign countries waste management policies. But in German policy, energy recovery from waste and pre-treatment are importantly considered and highly required for permission. Under current circumstance in korea, recycling will be more difficult than in the past. According to "The 4th resource recycling master plan", film type of synthetic resin was not sustainable recycled material in substance."Energy recovery from waste plan", proved that the energy recovery from RDF/RPF have lower efficiency than regular incineration generation and substance recycling. To solve these problems, the energy and remainder heat recovery must be generalized to "Energy recovery" concept and institutional improvement such as LCA(Life Cycle Assessment) system are need to support it. And also technology development to extract synthetic polymer by dissolved film type of synthetic resin must be provided.