• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.116-120
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• 2011

무심천에는 2002년부터 자연형 하천정비사업에 착수하면서 저수로, 저수로 하안, 고수부지 등 하도내에 여러 자연형 하천 공법과 함께 시설들을 설치하였다. 본 모니터링 조사사업은 '무심천 살리기'의 일환으로 이루어진 하천종합조사사업으로써 무심천의 수리/수환경 변화와 생태계의 변화를 조사를 통해 생태 수환경 수리특성 등 생태복원에 필요한 기초자료를 축적하고, 필요한 공법 등 향후 추진될 무심천 하천정비 및 관리에 반영하기 위하여 저수량, 홍수량, 생태계 및 하천공법 등에 대한 조사 및 분석을 전문가, 시민참여 그리고 공무원이 함께 수행하고 있다. 본 연구에서는 무심천을 친자연형 하천으로 복원하기 위하여 실시한 친자연형공법에 대하여 모니터링을 실시하고 얻은 수리/공학적 그리고 생태적 성과물을 자연형하천정비사업에 피드백시키는 자연형 하천관리방안에 대하여 논하였다. 무심천의 친자연형하천관리를 위하여 하천의 3대기능과 관련한 항목을 이용하여 평가지표를 설정하고, 평가를 하고 자연형 하천공법 등급을 I-V로 구분하여 하천관리를 위한 기준으로 사용하였다. 평 저수시 무심천 본류와 지류에 대한 유량측정을 실시하고, 하천유지유량을 산정하였다. 저수/고수호안, 하상, 둔치에 대한 조사분석을 실시하고 관리방안을 제시하여 무심천을 점차 자연형하천으로 변화시키고 있다. 또한 생태계의 적응관리로 하천식생을 유지하기 위한 관리를 실시하고, 유해식물과 외래식물을 제거하고, 하도내 직경이 10(m) 이상되는 버드나무 수목에 밑둥치기를 실시하여 치수기능의 저해를 방지하였다.

• Journal of Korea Water Resources Association
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• v.51 no.11
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• pp.959-969
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• 2018

The aging water pipes induce various problems, such as water supply suspension due to breakage, insufficient water pressure, deterioration of water quality, damage by sink holes, and economic losses due to water leaks. However, it is impractical and almost impossible to repair and/or replace all deteriorated water pipes simultaneously. Hence, it is required to quantitatively evaluate the deterioration rate of individual pipes indirect way to determine the rehabilitation order of priority. In this study, ANN(Artificial Neural Network)-Clustering method is suggested as a new approach to assess and assort the water pipes. The proposed method has been applied to a water supply network of YG-county in Jeollanam-do. To assess the applicability of the model, the evaluation results were compared with the results of the Numerical Weighting Method (NWM), which is being currently utilized in practice. The assessment results are depicted in a water pipe map to intuitively grasp the degree of deterioration of the entire pipelines. The application results revealed that the proposed ANN-Clustering models can successfully assess the water pipe deterioration along with the conventional approach of NWM.

• Membrane Journal
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• v.24 no.1
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• pp.20-30
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• 2014

A membrane-coupled sequencing batch reactor (MSBR) was used for the advanced treatment of rural village sewage which is very low C/N ratio. The effect of powdered activated carbon, aeration rate, and external organic material loadings on the treatment efficiency and filtration performance were investigated in sequencing batch reactor, in which a flat-sheet type microfiltration membrane with a pore size of $0.4{\mu}m$ was submerged. At the initial operation (within 54 days) MLSS concentration, and the removal efficiencies of COD, T-N, and T-P were increased with the increase of C/N ratio. After 89 days the removal efficiencies of COD, T-N, and T-P were 97.1%, 75.0%, and 48.3%, respectively. Suspended solid-free effluent was obtained by membrane filtration. The T-P removal was relatively low because of depending on the amount of excess sludge wasting. During the operation of MSBR with powdered activated carbon, the particle size of the sludge reduced by the increase of collision frequency and mixing intensity. In comparison with MSBR without powdered activated carbon, TMP of MSBR with that was significantly elevated.

• Korean Journal of Materials Research
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• v.8 no.11
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• pp.1067-1073
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• 1998

High quality diamond films of the silicon on diamond (SOD) structure are deposited using CO and $H_2$ gas mixture in microwave plasma chemical vapor deposition (CVD), a SOD structure is fabricated using low pressure CVD polysilicon on diamond/ Si(100) substrate. The crystalline structure of the diamond films which composed of { 111} and {100} planes. were changed from octahedral one to cubo-octahedron one as the CO/$H_2$ ratios are increased. The high quality diamond films without amorphous carbon and non-diamond elements were deposited at the CO/$H_2$ flow rate of 0.18. and the main phase of the diamond films shows (111) plane. The diamond/Si(lOO) structure shows that the interface is flat without voids. The measured dielectric constant. leakage current and breakdown field were $5.31\times10^{-9}A/cm^2$ and $9\times{10^7}{\Omega}cm$ respectively.

• Journal of the Korea Institute of Building Construction
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• v.10 no.3
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• pp.57-64
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• 2010

This study is to analyze the effects of aluminum form surface coating material on surface quality of concrete. When observing the surface quality of concrete affected by the change of aluminum form surface coating material, in general, as the number of use of the coating material increased, the surface quality of concrete decreased and good surface quality was shown in plywood (hereinafter PW). For epoxy (hereinafter EP) resin, when applying form remover, good surface quality was shown. For the surface roughness of concrete by the application form oil of form remover and the number of use of the coating material, as the number of use increased, highest surface roughness value was shown which meant the leveling was bad, but the surface roughness value in EP and PW was the lowest. Just for EP, when applying form remover, surface roughness value was low. For the number of void for concrete by the application of form remover and the number of use of the coating material, In general, the number of void which was generated when applying form oil the remover decreased.

• Journal of Korean Society of Forest Science
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• v.96 no.3
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• pp.283-289
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• 2007

Benefit-cost analysis is a useful tool for organizing information on the relative value of alternative public investments like national park preservation projects. When the value of all significant benefits and costs can be expressed in monetary terms, the net value (benefits minus costs) of the alternatives under consideration can be computed and used to identify the alternative that yields the greatest increase in public welfare. However, since goods and services of national parks are not commonly bought or sold in the marketplace, it can be difficult to express the outputs of a national park preservation project in monetary terms. In this case the dichotomous choice contingent valuation is employed to elicit the public benefit value. In this paper, a distribution-free approach, Turnbull empirical distribution model, is employed to analysis the benefit value of Woraksan National Park. The result is shown that annual use and preservation values of Woraksan National Park are estimated 6.5 and l37.4 billion won. Also, flow and stock values are estimated 143.9 and 3,021.7 billion won, respectively.

• Journal of Information Technology Services
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• v.16 no.2
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• pp.21-32
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• 2017

This study analyzes the variable consumer characteristics that influence the intention to use online product reviews. In online e-commerce, where purchases take place without consumers seeing the products in person, the product reviews left by other consumers who have already purchased the product are believed to be valuable information. However, when different consumers read the same product review, their responses to it may vary. This study analyzes the characteristics of consumers who utilize product reviews for their purchases. Consumer characteristics are categorized into personal information, personality, purchasing tendency, and experience related to product reviews. These factors are examined to see if they have direct or indirect effects on a consumer's intention to use product reviews when making online purchases. We surveyed a total of 240 consumers who had experience using e-commerce and knew about online product reviews. Once the data was collected, path analysis was conducted using the statistics tool AMOS. The study results reveal that consumers who are female, extroverted, and have higher price sensitivity think that product reviews left by others are useful, and that this "perceived usefulness" has a positive effect on the intention to use product reviews for making online purchasing decisions. In addition, consumers who are agreeable to others, have high brand sensitivity, and who have left numerous reviews themselves demonstrated the tendency to trust reviews left by others more. Thus, we conclude that this "perceived reliability" makes it more likely that a consumer will use product reviews when making online purchasing decisions. Future research can be done to develop this study further by analyzing whether providing online product reviews corresponding to the personal characteristics of consumers enhances the effect of product reviews on online purchasing decisions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.2
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• pp.75-86
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• 2016

The aim of this study was to compare the factors influencing internet game addiction among middle and high school boys. The data was analysed from "Survey on the Online and Game and Family Leisure Activities of Youth and Children in 2009" conducted by the Korean Youth Policy Institute. According to the results, the average time on the weekends and average time on the holidays, and the leisure constraints had a significant effect on the internet game addiction both groups. On the other hand, there were significant differences in the communication with parents between middle and high school boys. Accordingly, this study suggests a preventive internet game addiction program be developed. In addition, it is important to improve efficient communication skills between children and parents.

• The Korean Journal of Financial Management
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• v.12 no.2
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• pp.73-93
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• 1995

본 연구는 주식시장에서의 체결가격을 균형가격으로 가정하여 계산된 수익률에 관한 통계추정치의 편의에 관하여 분석하고 있다. 주식수익률의 통계적모멘트를 추정하는 것은 주식가격의 행태를 분석하는 연구 및 사건연구등에서 많은 학자들에 의하여 수행되어 왔다. 기존의 대부분의 연구들은 시장에서 체결된 가격이 그 시점의 진정한 균형가격이라는 가정하에 수익률을 계산하고 이 수익률 자료로부터 수익률의 평균, 표준편차, 외도(skewness), 침도(kurtosis) 등의 통계적모멘트를 추정하였다. 그러나 체결가격은 시장의 규칙에 의해 일정한 호가단위로만 거래될 뿐 아니라 매도 또는 매수호가에 거래됨으로써 진정한 균형가격과의 괴리가 있을 수 있게 된다. 본 연구는 주식호가단위의 불연속성과 매도매수호가의 차이로 연한 통계추정치의 편의에 관한 모형을 도출하여 편의의 크기와 특징을 분석하고, 이를 수정하는 간편식을 도출하여 그 유효성을 검증하고 있다. Gottlieb and Kalay(1985), Ball(1988), Cho and frees(1988)등은 1/8 달러의 최소호가단위로 인하여 발생하는 기존의 분산추정치의 편의를 계산하고 이를 수정하는 간편식을 제시하였다. French and Roll(1986)은 휴일이 포함된 기간의 수익률 분산과 평일 분산추정치의 비율이 기간과 비례하지 않는 원인중 하나는 매도매수호가차이로 인한 분산추정치의 편의라는 점을 설명한 바 있다. Choi and Shastri(1989)는 Black and Scholes 옵션가격 결정모형 이 주식 분산값의 크기에 따라 일정한 편의를 보이는 주요한 원인은 퍼센티지 매도매수호가차이와 옵션가격이 모두 진정한 분산치의 정의 함수이기 때문이라는 점을 보였다. Harris(1988)와 최종연(1994)는 주가의 불연속성 및 매도매수호가차이를 동시에 고려하여 기존의 분산추정치가 어떠한 편의를 보이는지에 관하여 분석한 바 있다. 본 연구에서는 최종연(1994)의 연구에서 도출된 모형을 연장하여 국내 주식시장과 같이 주가 수준에 따라 최소호가단위가 변화할 때의 변형모형을 도출하였다. 또한 이 모형에 따라 통계추정치의 편의를 수익률의 표준편차를 중심으로 계산하여 그 정도를 미국시장의 경우와 비교하였고, 그 추정치의 수정 방법에 대하여 호가단위가 변화하는 주가금액이 10,000원 주변일 경우를 중심으로 분석하였다.

• Journal of the Korean association of regional geographers
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• v.21 no.4
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• pp.660-672
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• 2015

The rural housing is a key element of the rural landscape. The studies on the rural housing have focused on folk housing, but this study focuses on the comtemporary rural housing. The research area is the eight rural settlements on the sea islands of Gyeongnam. This study may provide the base for an understanding Korean rural landscape through the analysis of the rural housing types with special reference to the roofing types and materials. Most roofing types but the flat roofing type belong to the traditional roofing types. Among the combined-style roofing(결합양식지붕) types, the pitched-and-flat roofing(경사-평지붕) type is about ten times more frequent than the pitched-and-pitched roofing(경사-경사지붕) type. The most frequent roofing materials are cement, precoated steel plate(컬러강판), and artificial slate(인조슬레이트). Five typical types of rural housing are derived from the remarkable combinations of roofing types and roofing materials in the research area.