• 터널과지하공간
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• 제10권3호
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• pp.410-417
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• 2000

절리가 발달한 암반의 거동 특성을 효율적으로 모델링 할 수 있는 수치해석 방법으로서 널리 알려진 개별요소법은 서로 다튼 알고리즘에 기초하여 개발된 두 가지 형태의 수치해석 방법으로 발전해 왔다. 본 논문에서는 Plesha 등에 의해 개발된 implicit 알고리즘에 기초한 NURBM과 저자에 의해 개발된 explicit 알고리즘에 기초한 CBLOCK을 이용하여 불연속체 암반의 기초적인 거동 특성을 수치해석적으로 고찰하고 모델링상의 문제점들을 비교 분석하였다. CBLOCK 계산 결과에 의하면 절리의 수직 및 접선 강성비는 절리 분포에 따라 불연속체 암반의 안정성을 좌우하는 중요한 지수로서 사용될 수 있는 것으로 나타나고 있으나 NURBM 계산은 상이한 결과를 보였다. 또한 구조물의 안정성과 국부적인 파괴 거동의 해석에서 두 방법이 상이한 결과를 가져올 수 있는 것으로 나타났고 이는 수치해석적 모델링의 제약적 요소로 작용할 수 있음을 보여주었다.

• 상하수도학회지
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• 제14권1호
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• pp.108-116
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• 2000

Chlorine is widely used as a disinfectant in drinking-water systems throughout the world. Chlorine residual was used as an indicator for prediction of water quality in water distribution systems. The variation of chlorine residual in drinking water distribution systems of Suwon city was simulated using EPANET. EPANET is a computerized simulation model which predicts the dynamic hydraulic and water quality behavior within a water distribution system operating over an extended time period. Sampling and analysis were performed to calibrated the computer model in 1999 (Aug. Summer). Water quality variables used in simulations are temperature, roughness coefficient, pipe diameter, pipe length, water demand, velocity and so on. Extended water residence time affected water quality due to the extended reaction time in some areas. All area showed the higher concentration of chlorine residual than 0.2mg/l(standard). So it can be concluded that any area in Suwon city is not in biological regrowth problem. Rechlorination turned out to be an useful method for uniform concentration of free chlorine residual in distribution system. The cost of disinfectant could be saved remarkably by cutting down the initial chlorine concentration to the level which guarantees minimum concentration (0.2mg/l) throughout the distribution system.

• 한국수소및신에너지학회논문집
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• 제28권6호
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• pp.669-674
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• 2017

In this study, the novel electrochemical and colorimetric analysis methods are suggested to estimate the degree of phosphoric acid ion poisoning on Pt based catalyst surface and to confirm the possibility of replacing the expensive and long time consumed conventional methods. As the ways, the electrochemical half cell tests such as cyclic voltammetry (CV) and linear sweep voltammetry (LSV) are used and the change in chemical behavior by absorption of the phosphoric acid ion on Pt based catalyst surface and hydrogen peroxide decomposition reaction are successfully recognized by colorimetric measurements. Conclusively, it is proved that the new methods show superior sensitivity for identifying the degree of phosphoric acid poisoned on Pt based catalyst.

• The Journal of Asian Finance, Economics and Business
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• 제4권4호
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• pp.51-60
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• 2017

India is the top recipient of workers' remittance flows; recent data indicate that the Remittances/GDP ratio has increased from 2.7% in 2000 to 3.36% in 2015. We apply a consumption behavior model, based on the "permanent income hypothesis", to estimate the consumption augmentation and the stability impact for the period of 1989-2014. The independent variables are: (i) real per capita income (exclusive of remittances) is the measure of "permanent income", (ii) remittances is the measure of "transitory income", and (iii) real interest rate as the indicator of consumers' ability for intertemporal consumption. The economic ramifications are important since current global risk factors could decrease flows in the future. The results indicate the significance of all three variables; there are: (i) evidence of significant consumption augmentation, (ii) consumption responds higher to remittances than to real income, the remittance elasticity is 0.571 and the income elasticity is 0.31, and (iii) evidence of pro-cyclical effect. The VAR model indicates some linkages and causality in the series that result in small response to the shocks. Policies to increase or stabilize remittance flows and to leverage remittances for economic development are important.

• 대한기계학회논문집
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• 제16권9호
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• pp.1736-1743
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• 1992

본 연구에서는 기화기부착 4행정 4기통 전기점화기관을 사용하여 흡기관내 액 막흐름에 의한 연료의 불균일화가 기관의 연소특성과 배기특성에 미치는 영향을 규명 하는데 궁극적인 목적을 두고 우선, 연소특성을 해석하기 위하여 비교적 고가인 연소 해석 시스템을 개발하는데 1차적인 목적으로 하였으며, 시험제작한 연소해석 시스템으 로 액막흐름의 가시화 및 배기가스 농도측정과 지압선도 해석을 행하여 구조적으로 대 칭인 1번과 4번 실린더의 연소특성과 배기특성을 비교 검토하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제11권3호
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• pp.31-44
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• 1987

Nowadays, the problems of energy and environmental pollution become serious day by day and the diesel engine, which has been proved to be superior to gasoline engine with respect to fuel consumption and ecological problems of exhaust gas, has been adopted widely for various purposes from the marine diesel engine and the dynamo engine to all kinds of engine on land. Therefore, extensive parametric studies on combustion of diesel engine should be done for its desing and improvement. To predict the behavior of diesel engien according to variable operating conditions by means of cycle simulation, the reasonable pattern of heat release rate has to be asumed. But it is necessary to know the actual variation of heat release rate in order to assume the reasonable pattern of heat release rate according to the actual operating conditions. In this paper, on a high speed small bore diesel engine with pre-combustion chamber, experimental investigations were carried out to determine the relationship between the heat release pattern and parameters such as engine load and speed. And also, the theoretical investigations about the performance variations of the above diesel engine according to the predicted pattern of heat release rate variation were performed. From the above observations, it may be said that the Fanboro indicator, which was used to get the cylinder pressure, can be used to estimate a reasonable pattern of heat release rate and it is confirmed that the pattern of heat release rate for the pre-combustion type engine is different from that of the direct injection type engine.

• Bulletin of the Korean Chemical Society
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• 제26권1호
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• pp.38-42
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• 2005

Bis(2-methylbenzaldehyde)butane-2,3-dihydrazone(TDSB) was used as new N-N Schiff's base which plays the role of an excellent ion carrier in the construction of a La(III) membrane sensor. The best performance was obtained with a membrane containing, 30% poly(vinyl chloride), 60% benzyl acetate, 6% TDSB and 4% sodium tetraphenyl borate. This sensor reveals a very good selectivity towards La(III) ions over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The proposed electrode exhibits a Nernstian behavior (with slope of 19.8 mV per decade) over a wide concentration range (1.0 ${\times}$ 10$^{-5}$-1.0 ${\times}$ 10$^{-1}$ M). The detection limit of the sensor is 7.0 ${\times}$ 10$^{-6}$ M. It has a very short response time, in the whole concentration range ($\sim$5 s), and can be used for at least twelve weeks in the pH range of 3.0-9.4. The proposed sensor was successfully applied as an indicator electrode for the potentiometric titration of a La(III) solution, with EDTA. It was also successfully applied in the determination of fluoride ions in three mouth wash preparations.

• 한국학교보건학회지
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• 제25권1호
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• pp.1-13
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• 2012

Purpose: This study was intended to identify the competency model for korean health teachers. In order to enhance job effectiveness and talent development of health teachers in schools, this study would provide policy makers and school administrators with a competency model to be used as a valid and reliable tool for selection, development, and appraisal of health teachers. Methods: This study used three-round Delphi technique, which was a series of surveys to obtain a consensus of experts in school health and health education. 31 experts were finally involved in Delphi panel, which consisted of professors, administrators, and school teachers. Results: This study found that the competency model of health teachers was composed of fourteen competencies and 75 performance indicators. The fourteen competencies were as follows: consulting and teaching competency, students understanding competency, health problem solving competency, health assessment competency, relationship building competency, information management competency, curriculum management competency, teaching activity competency, writing competency, professional expertise competency, health business management competency, self control competency, school commitment competency, and achievement orientation competency. Conclusion: Based on the results of this study, policy makers and school administrators would be able to use the competency model as a tool of new health teachers selection, existing health teachers appraisal, and new and existing teachers training and education. Future research needs to classify the levels of each performance indicator as a kind of behavior indices.

• 한국학교보건학회지
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• 제25권1호
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• pp.105-113
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• 2012

Purpose: The purpose of this study was to identify the statistical indicators of OECD and Korea for student health among Korea's approval statistics. Methods: Searching for health indicators by using Health at a Glance 2009, Society at a Glance 2009, and Education at a Glance 2009 through the formal OECD web site in 2010, and investigating the approval statistics through the Korean formal organizational web sites and published data in 2012. Results: Among OECD indicators, indicators for adolescent health were smoking and alcohol consumption, nutrition, physical activity, overweight and obesity, bullying, risk behaviors, and poverty children. However, most of Korea student health indicators were missing except poverty children and life satisfaction, because OECD has taken chiefly data from Health Behavior in School-aged Children survey (HBSC), international study, which has not been carried out in Korea. The Ministry Of Education, Science And Technology (MEST) and the Ministry of Health and Welfare, and National Youth Policy Institute in Korea have produced the major statistics for student health which was only 11 (1.3%) among 858 approval statistics. Conclusion: Identifying a current Korea school health is essential through participating actively to OECD whose statistic indicators are internationally comparable with Students Physical Development Survey, MEST's approval statistics, using Korea Student Health Examination. It was also suggested that quantitative and qualitative expansions for Korea student health statistics by the activation of approval statistics including processed statistics, and by researchers' easy expanded access to a raw data.

• 한국경영과학회지
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• 제40권4호
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• pp.107-121
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• 2015

Diffusion of innovation is the process in which an innovation is communicated through certain channels over time among the members of a social system. The literatures have emphasized the importance of interpersonal network influences on individuals in convincing them to adopt innovations and thereby promoting its diffusion. In particular, the behavior of opinion leaders who lead in influencing others' opinion is important in determining the rate of adoption of innovation in a system. Centrality has been recognized as a good indicator that quantifies a node's influences on others in a given network. However, recent studies have questioned its relevance on various different types of diffusion processes. In this regard, this study aims at examining the effect of a node exhibiting high centrality on expediting diffusion of innovations. In particular, we considered the situation where two innovations compete with each other to be adopted by potential adopters who are personally connected with each other. In order to analyze this competitive diffusion process, we developed a simulation model and conducted regression analyses on the outcomes of the simulations performed. The results suggest that the effect of a node with high centrality can be substantially reduced depending upon the type of a network structure or the adoption thresholds of potential adopters in a network.