• Title/Summary/Keyword: 잠재 변수

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기기냉각수 최저온도와 정지냉각계통 유량조절밸브 개도에 관한 설계분석

  • 김도현;이중섭;오종필;오광석
    • Proceedings of the Korean Nuclear Society Conference
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    • 1995.10a
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    • pp.444-449
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    • 1995
  • 한국형 표준 원자력발전소의 정지냉각운전시 최대냉각율은 75$^{\circ}$F/hr(41.7$^{\circ}C$/hr)로 기술사양서에 규정되어 있다. 정지냉각운전 냉각율에 가장 큰 영향을 미치는 2가지 중요한 변수는 정지냉각계통 열교환기를 지나는 원자로냉각재 유량과 기기냉각수의 온도다. 이중 열교환기를 지나는 원자로냉각재 유량은 butterfly형 정지냉각계통 유량조절밸브의 개도에 의하여 조절되는데 개도에 따른 throttle 능력이 중요한 인자다. 또 기기냉각수의 온도는 해수온도의 변화에 따라 편차가 발생하므로 유량조절밸브의 개도와 기기냉각수 온도의 상관관계에 따라 냉각능력이 달라진다. 본 논문에서는 현 울진 3&4호기 정지냉각계통 열 교환기 및 조절밸브 둥의 설비를 기준으로 기술사양서 상의 냉각율 75$^{\circ}$F/hr(41.7$^{\circ}C$/hr) 유지가 가능한 최저 기기냉각수의 온도를 찾아보았고, 아울러 기기냉각수의 온도와 조절밸브의 개도 사이의 관계를 조사하였다. 그 결과 현재의 울진 3&4호기 조절밸브를 최저개도로 조절할 때 약 57$^{\circ}$F(13.9$^{\circ}C$)의 기기냉각수가 공급되어도 냉각율 제한치를 넘지 않는 것으로 분석되었다. 한편, 최저조절가능 유량이 약 2000 gpm(7570 l/min)일 경우에는 낮은 기기냉각수가 공급될 경우 최대냉각율을 초과하므로 한 train을 정지시키고 한 train만으로 운전할 것을 고려하여야 할 것으로 보인다. 이 경우 최저 약 56.5$^{\circ}$F(13.6$^{\circ}C$)의 기기냉각수가 공급되어야 한다. 본 논문의 분석결과는 향후 기기설계사양서나 운전지침서 등에 반영되어 실제 발전소 설계 및 운전절차 수립에 기여할 수 있을 것으로 생각된다.공감대의 형성이 요구된다. 질적 측면에서는 공원 녹지의 기능성의 회복이라는 측면과 시대에 부합되는 새로운 기능 및 가치의 부여가 필요하며, 이를 위해서는 공원의 매력, 공원의 시설기능 증진, 녹지의 질의 향상 및 녹지 가치의 증진에 대한 다양한 시책이 요구된다. 구성적 측면에서는 공원녹지의 개별적 존재보다는 공원 녹지를 상호간 유기적인 계통을 확보하여 공원 녹지의 네트워크를 형성하여 도시 속의 산재된 고립된 섬으로서의 공원 녹지가 아닌 시민생활에 늘 가까이 있는 생활 속의 공원녹지로 재편되어야 한다. 이러한 정책의 의제는 양적 측면에서 보전(CONSERVATION)과 창출(CREATION), 질적 측면에서 쇄신(RENOVATION)과 복구(RESTORATION), 그리고 구성적 측면에서 공원 녹지의 연결(CONNECTION)과 시민 참여에 의한 운동(MOVEMENT)이라는 정책 개념의 구현을 통해 가능하다. 이러한 정책 개념과 의제를 가지고 서울시 공원 녹지 정책을 구체화시키기 위해서 푸르름의 새로운 탄생이라는 기치 아래 풍요로운 서울, 사랑 받는 공원, 생활 속의 녹지의 3대 목표, 공원 녹지의 보전, 잠재 공원 녹지의 창출, 공원의 활성화, 녹지의 복구, 경관 보전 및 복구, 공원 녹지의 네트워크, 도시 녹화의 7대 과제를 설정하고 미시설 공원 녹지 집행, 개발 사업시 공원 녹지의 확보, 환경 녹지의 총량 보호 관리, 도시 소공원 개발, 역사 문화 공원 조성, 하천 공간 복원, 공원 시설 기능 개선, 이용 프로그램 개발, 공원 관리 개선, 환경 피해 녹지의 회복, 도시 환경 림 조성, 녹지 기능 증진, 도시 자연 경관 보전, 공원 녹지체계 구성, 공원 녹지 공급 균형, 주변 환경 녹화, 가로 녹화의 17개 시책을 제안하였다. 이러한 정책사업의 원활한 추진을 위해서는 기존의 관주도의 일방적인 공원 녹지 행정이 아닌 시민의 참여를 통한 시민이 함께 하는 정 책 사업의 추진이 요구되며, 특히 민간 부문의

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The Longitudinal effect of parental depressive symptoms on language development, problem behavior, and school adjustment in the first grade child (부모의 우울이 초등학교 자녀의 언어발달, 문제행동 및 학교적응에 미치는 종단적 영향)

  • Kwon, Taeyeon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.1
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    • pp.338-348
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    • 2020
  • This study examined the longitudinal relationship between paternal depressive symptoms and maternal depressive symptoms simultaneously. This study also identified the interplay of paternal and maternal depressive symptoms for predicting elementary children's language development, their problem behaviors and their school adjustment. Using the data from the Panel Study on Korean Children for the 4th-8th years (2011~2015 year), this study used the Latent Growth Curve Model, which is helpful for examining longitudinal relationship differences among variables. The sample subjects were 1,754 parents and children. The results are as follows. The initial level of paternal depressive symptoms had a positive impact on the rate of change in maternal depressive symptoms. The initial level of maternal depressive symptoms had a negative impact on the rate of change in maternal depressive symptoms. Mothers' depressive symptoms showed not only the mothers' own depression problem. but also the self-effect and counterpart effect of depression on the fathers' depression problem. The rate of change in maternal depressive symptom mediated the relation between the initial level of parental depressive symptoms and children's receptive language, internalizing/externalizing problems, and school adjustment. Therefore, depression prevention and intervention programs for both fathers and mothers are needed for the healthy development and school adaptation of school-age children.

A Study on the Internet Game and Smartphone Usage of the Senior Elementary School Students (초등학교 고학년의 인터넷 게임 및 스마트폰 이용실태에 관한 연구)

  • Lee, In-Suk;Lee, Mi-Hyoung;Kim, Hee-Kyung;Park, Jeong-Sook;Son, Ji-Hye
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.10
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    • pp.421-432
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    • 2020
  • This study was designed to determine the Internet game and smartphone usage status of senior elementary school students. Data were collected from 6 October 2018 to 30 September 2019, and 1618 subjects were analyzed using SPSS 18.0. As a result of the study, the I-GUESS rating was 6.1% in the high-risk group, and, the S-scale ratios were 10.1% for the potential-risk group and 0.8% for the high-risk group. Physical problems related to Internet games and using smartphones were experienced by 36.0% of the students, with eye fatigue being the highest at 20.4%. Emotional problems were found in 18.5% of the students, with anger being the highest at 6.8%. Social problems were experienced by 21.8% of the students, conflicts with parents being the highest at 10.3%. As a result of surveying the main content based on S-scale and I-GUESS, it was found that the higher the S-scale ratio and the I-GUESS rating, the more broadcast content was used. The correlation between I-GUESS rating and S-scale ratio showed that the higher the I-GUESS rating, the higher the S-scale ratio, and the higher the S-scale ratio, the higher the I-GUESS rating. Future research is necessary to develop an intervention program for elementary school students from a preventive perspective.

Sensitivity Analysis and Parameter Evaluation of a Distributed Model for Rainfall-Runoff-Soil Erosion-Sediment Transport Modeling in the Naesung Stream Watershed (내성천 유역의 강우-유출-토양침식-유사이송 모의를 위한 분포형 모형의 민감도 분석 및 매개변수 평가)

  • Jeong, Won Jun;Ji, Un
    • Journal of Korea Water Resources Association
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    • v.47 no.12
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    • pp.1121-1134
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    • 2014
  • The distributed watershed model of rainfall-runoff-soil erosion-sedimen transport was constructed for the Naesung Stream Watershed with high potentiality and risk of sediments produced by soil erosion. The sensitivity analyses of roughness coefficient and hydraulic conductivity which affected the modeling results of runoff and sediment concentration were performed in this study. As a result, the change of the roughness coefficient for the forest area from 0.4 to 0.45 did not affect the change in runoff and stream discharge and the average value and range of sediment concentration were also insignificantly increased with few difference. As a result of the sensitivity analysis of the hydraulic conductivity, the total amount of runoff and maximum runoff were gradually increased as the hydraulic conductivity was reduced. In the case of sediment concentration modeling, the average and the range of sediment concentration for all stations were increased as the hydraulic conductivity was decreased. For the Hyangseok Station, in case of the hydraulic conductivity reduced by 50%, the simulation result of sediment concentration was most similar to the estimated value by the sediment rating curve.

Factors Affecting Smartphone Addiction among University Students (대학생 스마트폰 중독의 영향요인)

  • Cho, Gyoo-Yeong;Kim, Yun-Hee
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.3
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    • pp.1632-1640
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    • 2014
  • This study was conducted to investigate the factors affecting smartphone addiction of university students and to provide the data for developing intervention program of smartphone addiction prevention. The data were collected from 354 university students and analyzed with t-test and multiple regression by using SPSS 18.0 program. The smartphone addiction rate was 27.4%, which the high risk group rate was 6.2% and potential risk group rate was 21.2%. The significant factors of smartphone addiction were gender(${\beta}=0.149$, p<.001), average daily using time in week(${\beta}=0.292$, p=.001), average daily using time in weekend(${\beta}=0.390$, p<.001), wrist pain in using smartphone(${\beta}=0.148$, p<.001), accident in using smartphone(${\beta}=0.133$, p=.002), sociality(${\beta}=-0.099$, p=.029), impulsiveness(${\beta}=0.211$, p<.001), SNS addiction(${\beta}=0.376$, p<.001). And these factors explained 43.3% of the variance in smartphone addiction. In conclusion, the results from this study indicated a need to develop the intervention program to prevent smartphone addiction considering these factors affecting smartphone addiction.

The Impact of Unit Pricing System on the Demand for Solid Waste Disposal, Food Waste Disposal, and Recyclables (종량제 가격이 생활폐기물, 음식물쓰레기, 재활용품 수거서비스 수요에 미치는 영향)

  • Hong, Seonghoon
    • Environmental and Resource Economics Review
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    • v.24 no.4
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    • pp.747-761
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    • 2015
  • This paper investigates the impact of an increase in unit price of solid waste collection on demand for alternative solid waste disposal types. I control for other variables affecting the demand and employ both community and time fixed effects models in the estimation of each reduced-form demand functions. Estimation results show that an increase in unit price reduces the demand for garbage bag collection services of non-food solid wastes while it increases the demand for food wastes and source-separated recyclables. These results imply that reduction in the demand for non-food solid wastes collection is mainly achieved by increasing the amount of recyclables and food wastes collected. However, it appears that an increase in unit price increases the total amount of solid wastes generated. This suggests that price incentive effects are offset by the decrease in source-reduction efforts because of feedback effects resulting from the increase in recycling, food waste separation, and illegal disposal of wastes.

Estimation of Potentially mineralizable nitrogen of organic materials (유기자원의 무기화량에 의한 질소 공급량 추정)

  • Lee, Sang-Min;Shin, J.H.;Lee, Y.;Yun, H.B.;Jung, M.C.;Oh, J.S.;Kim, H.S.;Kim, K.H.
    • Proceedings of the Korean Society of Organic Agriculture Conference
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    • 2009.12a
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    • pp.299-299
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    • 2009
  • 유기농업에서 유기자원을 이용하여 적정량의 양분을 공급하기 위해서는 먼저 유기자원의 무기화특성을 고려하여야 한다. 토성, 기온, 재배형태 등 다양한 요인을 고려하면서 무기화모델을 이용하여 유기농업에서 많이 사용되고 있는 유기질비료와 작물잔사 등을 대상으로 잠재 무기화가능 질소량(PMN, Potentially mineralizabe nitrogen)을 추정하였다. 실험은 실내에서 항온 배양하여 유기자원별 질소 무기화 양상을 분석함으로서 대상 유기자원의 PMN 및 무기화 속도를 도출하였다. 실험재료는 팜박, 피마자박, 팽화왕겨, 토마토, 수박, 감자, 마늘 등 7종을 대상으로 $20^{\circ}C,\;25^{\circ}C,\;30^{\circ}C$ 조건에서 하였으며, 최대수분보유량의 60% 수준으로 하여 사양토 및 식양토 조건에서 실험하였다. 유기자원은 토양 100g에 질소 30kg/10a 해당량을 시용하여 112일까지 항온하였다. 토성별 무기화량은 식양토 보다 사양토에서 다소 높은 경향을 보였다. 또한 항온온도가 높을수록 무기화량이 증가하였다. 유기자원별로는 피마자박에서 높았고, 팽화왕겨는 낮은 경향이었다. 유기자원이 처리된 것에서 토양 자체의 무기화량을 뺀 순무기화량은 피마자박, 토마토잔사, 감자잔사가 항온초기부터 무기화가 진행되었으며, 수박잔사, 마늘잔사는 항온 초기에 음의 값을 가지는 유기화 과정을 거친 후 항온 60일에서 80일 사이에서 무기화가 진행되었고 팽화왕겨의 경우 항온 11일까지 유기화가 계속되었다. PMN 및 무기화속도를 추정하기 위하여 반응속도식을 이용하였으며, 모델의 적합도를 높이기 위하여 이중지수모형을 이용하여 매개변수를 결정하고 무기화경향을 예측한 결과 PMN은 피마자박>마늘잔사=팜박>수박잔사=토마토잔사>감자잔사의 순이었다. 또한 유기자원의 무기화량과 C/N율과는 부의 상관관계($r^2$=0.8653)를 나타내었다. 요소의 PMN(135.6mg/kg)에 대한 유기자원별 PMN의 상대적 비율은 피마자박이 100%, 팜박과 마늘잔사가 81%, 토마토, 수박 및 감자잔사가 28~65% 수준이었다.

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Three Hypothesis Tests for Determinants of Business Start-up (산업별 창업 결정요인의 세 가지 가설 검증, 2008-2014년)

  • Lee, Changkeun
    • Journal of the Korean Regional Science Association
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    • v.33 no.1
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    • pp.17-27
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    • 2017
  • The purpose of this study is to analyze the determinants of start-ups by industry based on the theoretical background of entrepreneurship. For this purpose, regional industrial structure and local labor market structure are considered in order to focus on regional factors in addition to economic factors, income factors, and technological innovation factors. As an analyzed result, three theories of entrepreneurship generally agree with the determinants of industry - specific entrepreneurship. During the economic recession, the number of start-ups has increased. The intra-regional consumption and the local government expenditure per capita have also positive effects on the start-up. The incubation center has a positive effect on the start - up in the manufacturing sector. Therefore, the academic-industrial leading various incubation facilities should be activated in addition to the central or local government leading incubation centers, which is a part of the policy to support start-ups of central and local governments. In addition, population growth is a very important factor in terms of potential demand creation, and the characteristics of regional industrial structure and the effect of human capital within the region differ by industry. In the case of the manufacturing industry, the accumulation effect positively influences the start-up of the industry. In other service industries, the human capital variable had the greatest effect on the start-up when all other conditions are constant.

Short-term Traffic States Prediction Using k-Nearest Neighbor Algorithm: Focused on Urban Expressway in Seoul (k-NN 알고리즘을 활용한 단기 교통상황 예측: 서울시 도시고속도로 사례)

  • KIM, Hyungjoo;PARK, Shin Hyoung;JANG, Kitae
    • Journal of Korean Society of Transportation
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    • v.34 no.2
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    • pp.158-167
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    • 2016
  • This study evaluates potential sources of errors in k-NN(k-nearest neighbor) algorithm such as procedures, variables, and input data. Previous research has been thoroughly reviewed for understanding fundamentals of k-NN algorithm that has been widely used for short-term traffic states prediction. The framework of this algorithm commonly includes historical data smoothing, pattern database, similarity measure, k-value, and prediction horizon. The outcomes of this study suggests that: i) historical data smoothing is recommended to reduce random noise of measured traffic data; ii) the historical database should contain traffic state information on both normal and event conditions; and iii) trial and error method can improve the prediction accuracy by better searching for the optimum input time series and k-value. The study results also demonstrates that predicted error increases with the duration of prediction horizon and rapidly changing traffic states.

Diversion Rate Estimation Model for Unexperienced Transportation Mode by Considering Maximum Willingness-to-pay: A Case Study of Personal Rapid Transit (최대 지불의사액을 고려한 미경험 교통수단의 전환율 추정모형: Personal Rapid Transit 사례를 중심으로)

  • Yu, Jeong Whon;Choi, Jung Yoon
    • Journal of Korean Society of Transportation
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    • v.31 no.3
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    • pp.33-44
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    • 2013
  • Personal Rapid Transit(PRT) has emerged as a promising transportation mode for transit-oriented sustainable communities. In this study, an alternative design of questionnaire survey is proposed in order to capture traveler's perception of an unexperienced transportation mode. This study aims at predicting the mode choice diversion behavior of potential PRT users who do not have experience of using it previously, considering their willingness-to-pay. The proposed model was applied to predict an aggregate forecast of PRT patronage for the city of Songdo where PRT is considered to be constructed. For validation of the proposed model, the price elasticity of PRT demand was analyzed, compared with existing models. The analysis results suggest that the proposed design of questionnaire survey is able to capture respondents' attitude and perception to unexperienced transportation mode in an effective manner. Also, they show that the proposed diversion rate model is more realistic than existing models in explaining the effects of users' willingness-to-pay for predicting PRT patronage.