• Structural Engineering and Mechanics
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• 제52권5호
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• pp.857-873
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• 2014

Structural behaviors of a sustainable hybrid column with the ultra high performance cementitious composites (UHPCC) permanent form under compression and flexure were studied. Critical state and failure stage characters are analyzed for large and small eccentricity cases. A simplified theoretical model is proposed for engineering designs and unified formulas for loading capacity of the hybrid column under compression and flexure loads are derived, including axial force and moment. Non-linear numerical analysis is carried out to verify the theoretical predictions. The theoretical predictions agree well with the numerical results which are verified by the short hybrid column tests recursively. Compared with the traditional reinforced concrete (RC) column, the loading capacity of the sustainable hybrid column is improved significantly due to UHPCC confinements.

• Geomechanics and Engineering
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• 제29권5호
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• pp.583-598
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• 2022

The Compaction effect is important for evaluating the subgrade construction. However, there is little research exploring the compaction quality of deep soil using hydraulic compaction. According to reinforcement effect analysis, dimensional analysis is adopted in this work to analyze subgrade compactness within the effective reinforcement depth, and a prediction model is obtained. A hydraulic compactor is then employed to carry out an in-situ reinforcement test on gravel soil subgrade, and the subgrade parameters before and after reinforcement are analyzed. Results show that a reinforcement difference exists inside the subgrade, and the effective reinforcement depth is defined as increasing compactness to 90% in the depth direction. Layered compactness within the effective reinforcement depth is expressed by parameters including the drop distance of the rammer, peak acceleration, tamping times, subgrade settlement, and properties of rammer and filler. Finally, a field test is conducted to verify the results.

• 생태와환경
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• 제43권1호
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• pp.161-167
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• 2010

In this study, we implemented an experimental approach of ecological model development in order to emphasize the importance of input variable selection with respect to time-delayed arrangement between input and output variables. Time-series modeling requires relevant input variable selection for the prediction of a specific output variable (e.g. density of a species). Inadequate variable utility for input often causes increase of model construction time and low efficiency of developed model when applied to real world representation. Therefore, for future prediction, researchers have to decide number of time-delay (e.g. months, weeks or days; t-n) to predict a certain phenomenon at current time t. We prepared a total of 3,900 equation models produced by Time-Series Optimized Genetic Programming (TSOGP) algorithm, for the prediction of monthly averaged density of a potamic phytoplankton species Stephanodiscus hantzschii, considering future prediction from 0- (no future prediction) to 12-months ahead (interval by 1 month; 300 equations per each month-delay). From the investigation of model structure, input variable selectivity was obviously affected by the time-delay arrangement, and the model predictability was related with the type of input variables. From the results, we can conclude that, although Machine Learning (ML) algorithms which have popularly been used in Ecological Informatics (EI) provide high performance in future prediction of ecological entities, the efficiency of models would be lowered unless relevant input variables are selectively used.

• 정보교육학회논문지
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• 제18권2호
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• pp.345-356
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• 2014

인터넷 서비스는 개방, 공유, 참여의 성격을 표방하여 인터넷 환경에 사용자가 적극적으로 참여하는 형태로 변화하고 있다. 본 연구에서는 이러한 흐름에 부응하여 기존의 로봇 프로그래밍 모형을 바탕으로 웹2.0 환경에 부합하는 긍정적인 상호작용을 촉진하기 위한 교육모형을 제안하였다. 우선 웹2.0의 환경의 특성과 이를 구현할 수 있는 교육적 도구에 대해 고찰하였고, 지금까지 연구되어 온 로봇 교육 및 로봇 프로그래밍 교육과 학습모형에 대해 살펴보고 시사점을 도출하였다. 또한 협력적 상호작용을 촉진할 수 있도록 웹2.0 도구(싸이월드, prezi, mindmeister)를 활용한 교육모형을 구안하고 이를 학습자에게 적용해보았다. 본 연구 결과 웹2.0 기반의 도구를 활용한 로봇 프로그래밍 교육이 유의미하다는 결과를 얻을 수 있었으며, 참여한 학습자 대부분은 웹2.0의 도구를 활용하는 것이 로봇 프로그래밍 과정 전반에 도움이 되었다고 평가하였다.

• 대한지역사회영양학회지
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• 제20권1호
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• pp.1-10
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• 2015

Objectives: This study was conducted to develop and validate Eating Behaviors Test form (EBT) for infants and young children, including eating behaviors of their parents and parental feeding practices. Methods: Draft version of EBT form was developed after a pretest on 83 mothers. It was consisted of 42 questions including 3 components; eating behavior of children, eating behavior of parents, and parental feeding practices. Using these questionnaires, the first survey was conducted on 320 infants and children, 1 to 6 year old, for exploratory factor analysis, and the second survey was collected on 731 infants and children for confirmatory factor analysis. Results: Exploratory factor analysis on 42 questions of EBT form resulted in 3 factor model for children's eating behavior, 3 factor model for parents' eating behavior, and 1 factor model for parental feeding practices. Three factors for children's eating behavior could be explained as follows; factor 1, pickiness (reliability ${\alpha}=0.89$; explanation of variance=27.79), factor 2, over activity (${\alpha}=0.80$, explanation of variance=16.51), and factor 3, irregularity (${\alpha}=0.59$, explanation of variance=10.01). Three factors for mother's eating behavior could be explained as follows; factor 1,irregularities (${\alpha}=0.73$, explanation of variance=21.73), factor 2, pickiness (${\alpha}=0.65$, explanation of variance= 20.16), and factor 3, permissiveness (${\alpha}=0.60$, explanation of variance=19.13). Confirmatory factor analysis confirmed an acceptance fit for these models. Internal consistencies for these factors were above 0.6. Conclusions: Our results indicated that EBT form is a valid tool to measure comprehensive eating and feeding behaviors for infants and young children.

• 한국공간구조학회논문집
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• 제16권1호
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• pp.53-64
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• 2016

Solar power is being spotlighted recently as a new energy source due to environmental problems and applications of solar power to curved structures are increasing. Solar panels installed on curved surfaces have different efficiencies depending on its position and the efficient positioning of solar panels plays a critical role in the design of solar power generation systems. In this study, the changing characteristics of solar irradiance were analyzed for hemispherical dome with a large curvature and the positioning of solar panels that can efficiently utilize solar energy was investigated. With an icosahedron-based hemispherical dome consisting of triangular elements as target model, a program for calculating solar irradiance using a normal vector of the solar module on each face was developed. Furthermore, the change of solar irradiance according to the sun's path was analyzed by time and season, and its effects on shades were also examined. From the analysis results, the effective positioning could be determined on the basis of the efficiency of the solar panels installed on the dome surfaces on solar irradiance.

• 한국학교ㆍ지역보건교육학회지
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• 제18권2호
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• pp.1-25
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• 2017

Objectives: There is higher rates of experience of suicide ideation and suicide attempt of adolescents in the Lima and Callao region compared with the results of the epidemiological study (2013) conducted by Peru National Institute of Mental Health and the Global School-based Student Health Survey (2010) which is was conducted among adolescents across all regions of Peru. Based on the PRECEDE model, this study analyzed the prevalence and the factor associated with the suicide attempt among the adolescent in a poor urban area in Peru. Methods: A stratified random sampling was used for the survey to select study participants from the 6 secondary schools based in Comas or Callao. The survey was conducted November 25th and December 4th in 2015 and a total of 738 individuals included in the analysis. In order to analyze factors influencing suicide attempt, comparison of predisposing factor, reinforcing factor, enabling factor, behavioral factor, environmental factor, psychological factors by suicide attempt and suicide risk group were identified through the chi-square test and hierarchical logistic regression. Results: Results showed that those who reported having less parental understanding, less time spent with parents, and 'almost none/none' for parental affection had more experience of suicide attempt and were more likely to sort into the high suicide risk group. Also, a greater proportion of those with the experience of suicide attempt had more experience of smoking and alcohol consumption, and experience of physical abuse and feeling insulted and depression in comparison to that of those without experience of suicide attempt. Variables that had a significant effect on suicide attempt included depression, subjective happiness, smoking experience, sexual intercourse, involvement in fight, parental affection, and gender (male). Conclusions: The results of the current study can serve as grounds for the necessity of acknowledging that adolescent suicide does not simply depend on a couple of factors, but arises from situations in which individual, home, school, social factors influence one another, and therefore adolescent suicide should be prevented and addressed through a multi-dimensional and integrated approach.

• The Journal of Asian Finance, Economics and Business
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• 제8권8호
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• pp.465-473
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• 2021

This study is the application of a choice experiment to assess Mekong Delta urban households' preferences and motivations for ecosystem conservation in the U Minh forest. The study applied a choice modeling approach to estimate the economic values of the proposed ecosystem conservation program in the U Minh forest by accessing urban consumer preferences and their willingness to pay for the project. Discrete choice experimental data was collected from 450 residents in the cities of the Vietnamese Mekong Delta. The multinomial logit model was employed to identify consumer's stated preferences for the environmental and sustainability attributes of the conservation project. The results showed that Mekong Delta urban residents paid much attention to the proposed project to protect and develop the U Minh forest. In addition, the results showed that higher education, income, and knowledge of the U Minh forest revealed a higher likelihood of selecting the project, while the older residents would select the status quo more than the younger ones. The study also proved that the effect of participation had a strong impact on the willingness to pay for the project. The findings could be useful for policymakers to take action to raise resident's awareness and willingness to pay for the U Minh forest project.

• 한국경제지리학회지
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• 제12권4호
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• pp.627-644
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• 2009

지식기반사회로 진전됨에 따라 경제성장의 원동력으로서 인적자본(human capital)의 중요성이 부각되면서 인적자본의 외부효과에 대한 관심이 매우 높아지고 있다. 본 연구는 근로자의 임금에 영향을 주는 결정요인을 개인 수준, 기업 수준, 지역 수준별로 위계선형모형을 구축하여 인적자본의 외부효과를 분석하는데 목적을 두었다. 또한 지식확산의 강도가 학력그룹별로 다를 것이라는 가설 하에서 고학력자 그룹과 저학력자 그룹의 인적자본의 외부효과를 비교하였다. 3단계 위계선형모형 추정 결과 지역의 평균 교육수준이 1년 증가할 때 근로자의 평균 임금이 4.4% 상승하는 것으로 나타나, 인적자본의 외부효과가 있음을 말해준다. 이러한 인적자본의 외부효과는 학력수준 집단별로 차이를 보이는 것으로 나타났다. 즉, 학력수준을 고졸 이하와 전문 일반대 졸업, 그리고 석 박사 졸업으로 그룹화하여 인적자본의 외부효과를 산출한 결과 각각 3.0%, 4.7%, 11.8%로 나타나, 고학력으로 갈수록 인적자본의 외부효과가 더 크게 나타나고 있다. 이와 같이 학력 수준별 인적자본의 외부효과가 상이하게 나타나며, 고학력으로 갈수록 외부효과가 더 커지고 있다는 점을 고려해 볼 때 지방의 경쟁력을 살리기 위해서는 인적자본의 외부효과를 높일 수 있는 방안을 적극적으로 모색하여야 할 것이다.

• 한국초등과학교육학회지:초등과학교육
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• 제43권1호
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• pp.108-121
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• 2024

이 연구에서는 프로젝트 기반 학습 전략을 사용한 지속가능성 교육 프로그램을 개발하고 예비 교사를 대상으로 적용하여 그 효과를 분석하였다. 교육대학교의 4학년 학생 23명이 연구에 참여하였고, 사전 검사로 환경 관련 행동 및 태도 검사를 실시하였다. 지속가능성 교육 프로그램을 5주에 걸쳐 실시하였고, 학생들은 전기 절약 프로젝트를 각자 수행하였다. 사후 검사는 사전 검사와 같은 검사지를 사용하였고, 프로젝트에 적극적으로 참여한 아홉 명을 대상으로 개별 면담을 하였다. 면담 내용과 포트폴리오 및 결과 보고서를 심층적으로 분석하여 지속가능성 교육 프로그램의 효과와 원인에 관련된 하위 개념을 도출한 뒤 유목화하여 하위 범주를 설정하였다. 다음으로 하위 범주 사이의 관계 중 반복해서 나타나는 관계를 추출하여 잠정적인 설명 모형을 도출하였다. 연구 결과, 프로젝트 기반 지속가능성 교육 프로그램은 학생들의 친환경적 행동과 가치 및 태도를 긍정적으로 변화시켰다. 학생들의 친환경적 행동에 뚜렷하게 영향을 미친 원인은 '성공으로 얻은 성취감'이었다. 그리고 일부 원인은 가치 및 태도 측면을 매개로 학생들의 친환경적 행동에 간접적으로도 영향을 미치는 것으로 나타났다.