• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.786-788
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• 2005

전력 부하관리기기인 축냉시스템은 그동안 건물 냉방 공조용을 중심으로 보급되었다. 기저부하를 증진시키고 주간의 피크부하를 낮추어 주야간의 부하불균형을 해소하는 축냉시스템은 그동안 전력부하율 향상 및 부하평준화에 많이 기여해왔다. 산업용으로의 축냉기기보급의 타당성 및 부하평준화에 관한 연구시행 결과, 그 타당성과 보급확대의 필요성이 확인 되었다. 가스식 냉방기는 피크억제측면에서, 축냉식은 부하이전 측면에서 장점이 매우 크며, 전체 부하관리 측면에서 이들의 균형보급발전 노력이 필요하다. 산업용으로의 축냉기기 보급은 특히 주야간 부하불균형이 심한 하계의 부하평준화효과가 크며, 그 보급시장 및 전력절감 잠재량 규모를 감안할 때 국가적 편익과 추가 발전설비건설억제에 크게 기여할 것으로 예상된다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1879-1880
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• 2008

시간 데이터마이닝은 기존 데이터마이닝에 시간 개념을 추가하여 시간 속성을 가진 데이터로부터 이전에 잘 알려지지는 않았지만 묵시적이고 잠재적으로 유용한 시간 지식을 탐사하는 기술이다. 이 논문에서는 시간 속성을 가진 변압기 부하 패턴에 대해 시간의 변화에 따른 적용 시점이 명확한 지식 탐사가 가능하고, 향후 부하 예측에 있어 탐사된 규칙과 시간 지식을 이용함으로써 기존의 정적인 분류규칙을 적용한 방법보다 더 정확한 예측을 할 수 있는 새로운 시간 패턴 마이닝 기법을 제안한다.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.724-730
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• 2004

본 연구에서는 GIS와 연계되는 SWAT 모형을 이용하여 소양강댐 유역의 일 유출량을 모의하였으며, 모형에서 제공하는 단일 지점을 이용하는 기본 방법과 다지점 강우를 이용하기 위한 방법으로 나누어 비교하였다. 모형의 민감도 분석을 통해 매개변수를 최적화 하였고, 잠재 증발산량을 산정하기 위하여 Penman-Monteith 방법을 이용하였다. 과거의 관측 수문곡선을 SWAT 모형에 의해 모의된 일 유출 수문곡선과 비교한 결과, 두 가지 방법 모두 총 유출체적은 물수지에 기본을 둔 모형의 특성상 잘 일치 하였다. 그러나 갈수기와 홍수기의 일 유출 수문곡선은 다지점의 강우자료를 이용한 경우가 더 적합함을 알 수 있었다. 또한 SWAT 모형이 장기 일 유출량 모의에 적용 가능함을 확인하였다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.7
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• pp.982-990
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• 2019

The interest of researchers and governments in exploiting tidal energy resources is increasing. Jangjuk strait is a place with high tidal energy density potential and is therefore appropriate for the constructing of a tidal turbine farm. In this study, a numerical approach is presented to evaluate the current flow and power potential in Jangjuk strait with an ADCIRC model. Then, the tidal field characteristics are utilized as input parameters for tidal resource calculation with an in-house program. The 1 MW scale tidal energy converter devices are employed and arranged in 4 layouts to investigate the annual energy yield as well as flow deficit due to the wake ef ect at the surveyed area. The best-performed array generates an annual energy yield up to 12.96 GWh/year (without considering the wake effect); this value is reduced by 0.16 GWh/year when accounting for the energy loss caused by the flow deficit. Moreover, by altering the turbine yaw angle during the flood and ebb tides, the impacts of this factor on the energy extraction are analyzed. This indicates that the turbine array attains the maximum tidal power when the turbine yaw angle is at 346° and 164° (clockwise, to the North) for the spring and neap tide in turns.

• Land and Housing Review
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• v.5 no.4
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• pp.247-257
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• 2014

This study proposes a new housing need and demand assessment model centering on small-scale housing development projects and happy house development projects that reflected the recent changes in rental and small sized apartment centered public housing policies and development paradigms. The housing need and demand assessment model of public housing development projects consists of quantitative evaluation factors such as potential need indicator and demand pressure indicator and qualitative evaluation factors such as local condition indicator. The potential need indicators of small sized housing development projects are calculated by subtracting the stock of already-supplied constructed rental and purchased rental housings from the potential quantity of need drawn from the small regions such as -eup, -myeon, and -dong. In the potential need indicators of happy house development projects, the potential need is calculated from those who are expected to receive a happy house in the unit of -si, -gun, and -gu. In small-sized housing development projects, demand pressure indictors are the number and the proportion of those who opened a subscription deposit, the number of those who received basic livelihood security and the number of those who were patriots and veterans. The demand pressure indicators of the happy house development projects are stock ratio of small-sized houses, rate of rise in housing rent price, level of housing rent price, and rate of monthly rent house.

• Clean Technology
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• v.28 no.2
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• pp.123-130
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• 2022

Nanoparticles are used in various fields such as chemistry, medicine, the environment, and information and communication. With the increasing use of engineered nanomaterials, exposure to nanoparticles is expected to increase in the workplace and the environmental media. However, while nanotechnology industries are expanding, research on the exposure assessment of nanomaterials to humans and the environment is only at a beginning stage. Especially, if nanoparticles with a size of 100 nm or less that are contained in nano-products are released unintentionally, they may pose potential risks to the human body through breathing or skin exposure. Therefore, in this work, the possibility of potential exposure of nanoparticles moving from the laboratory to the office was confirmed, and nanoparticle safety guidelines are proposed. A nano-collector was used to detect nanoparticles in the atmosphere, and through use of a scanning mobility particle sizer it was found that nanoparticle concentrations in the laboratory and the office tended to be similar. On the assumption that nanoparticles attached to a lab-coat move out of the laboratory, a lab-coat to which nanocarbon black was attached was shaken and the concentration of the remaining particles on the lab-coat determined. The results confirmed that sufficient amounts of nanoparticles attached to the lab-coat could move from the laboratory to the office along the path of a researcher; thus, safety guidelines for the handling of lab-coat nanoparticles are required.

• 한국노년학
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• v.31 no.3
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• pp.733-749
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• 2011

The purpose of this research are as follows. The first is to investigate the mediating effect of interpersonal skill on the relationship between the ability to use Internet and social activity among the 50's and 60's. The second is to compare 60's latent mean of core variables with 50's ones in terms of information gap. The data was Seoul welfare panel data made by Seoul welfare foundation in 2008 and the total subject was 941(50's=644, 60's=297). When it comes to the research methods, structured equation analysis for verifying the mediating effect and latent mean analysis for comparing the two groups were practiced. The results of this research are as follows. First of all, interpersonal skill did function as partial mediator. Second, according to the latent mean analysis, the group of 50's showed a more higher level of the ability to use Internet. On the other hand, the group of 60's revealed a more active social participation. In conclusion, Information educational programs should focus on Internet communication skill for enhancing social activities of the elderly and consider the differentiations among the elder generations.

• Journal of the Korean School Mathematics Society
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• v.23 no.3
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• pp.277-297
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• 2020

The purpose of this study is to understand how the shift of the Pythagorean theorem influenced the representation of irrational numbers in the 3rd grade textbook of 2015 revised mathematics curriculum by textbook analysis. Specifically, the changes in the representation of irrational numbers were examined in two aspects based on the nature of irrational numbers and the teaching and learning methods of the 2015 revised mathematics curriculum. First, we analyzed the learning opportunities related to the existence of irrational numbers that were potentially provided by treating irrational numbers as geometric representations in textbooks, and confirmed that Pythagorean theorem was used. Next, we analyzed opportunities to recognize the necessity of irrational numbers provided by numerical representations of irrational numbers. This study has significance in that it confirmed the possibility and limitation of learning opportunities related to the existence and necessity of irrational numbers that were potentially provided by changes in irrational number representations in the 2015 revised textbooks.

• Journal of the Korean Society of Child Welfare
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• no.40
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• pp.41-71
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• 2012

The purpose of this study is to examine longitudinal impacts of various factors on happiness in primary school children. Specifically, attachment theory and ecosystems perspective were utilized for the purpose of this study. We used Korea Youth Panel Survey, which is a 5-year longitudinal data collected from fourth grade in elementary school to second grade in middle school Latent growth model was employed as the analytic method. The findings of this study are as follow: first, academic achievement, self-esteem, parent attachment, peer attachment, teacher attachment, and community attachment all decreased over the 5-year study period. Also, the intercept and the slope variance of variables were found to be statistically significant. This means that there are significant differences in the intercept and the slope of individuals. Second, self-esteem, parent attachment, and peer attachment were found to have cross-sectional influences on happiness. This means that self-esteem, parent attachment, and peer attachment are positively associated with happiness at the intercept. Also, self-esteem, parent attachment, teacher attachment, and community attachment were found to have longitudinal influences on happiness. This means that the higher levels of community attachment at the intercept is associated with slower the rate of decrease in happiness at the slope. In addition, faster rates of decrease in self-esteem, parent attachment, teacher attachment, and community attachment are associated with faster the rate of decrease in happiness. Third, this study conducted multiple group analysis with gender. The findings of this analysis revealed no significant differences in analytic models between males and females. Based on these findings, theoretical and practice implications with regard to happiness in primary school children are discussed.

• 한국노년학
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• v.38 no.4
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• pp.963-979
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• 2018

The purpose of this study was to identify frailty profiles based on physical, psychological, and social domains of functioning and to examine the associated factors showing the differences among frailty profiles. Respondents were 70 years and older(n=403) and latent class analysis was applied to determine the optimal subgroups based on Tilberg Frailty Indicators which comprised of three domains(the physical, psychological, and social domain). Also, we performed multinominal logistic regression analysis to find out factors making differences among frailty profiles. Latent class analysis(LCA) identified three distinct types: multi-frail type(27.0%), psychologically frail type(26.8%), inadequate support type(46.2%). All three types had common difficulties in dealing with daily life problems and did not receive enough help with theses difficulties. Based on the results of the LCA three-class models, people in multi-frail type accumulated problems in physical and psychological domains and had partially social domain. On the other hands, psychologically frail type showed a relatively high anxiety disorder and depression. Lastly, people in inadequate support type reported the lack of helps, but they were relatively healthy. Comparing these groups with inadequate support type, people with multi-frail had lower educational level, poor nutritional management status and were less likely to participate in labor market. People in psychologically frail type were more likely to be male, to live in big cities rather than middle and small cities, and less likely to smoke. Based on these results, our results showed the multifaceted concept of frailty among Korean elderly people and we suggested several implications for preventing frail process.