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A Study about Effectiveness and Usefulness of a FEM Slug Test Model (유한 요소기법을 이용한 Slug시험 모델의 타당성 및 유용성 연구)

  • 한혜정;최종근
    • Journal of the Korean Society of Groundwater Environment
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    • v.7 no.2
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    • pp.89-96
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    • 2000
  • Slug tests are the most widely used field method for quantification of hydraulic conductivity of porous media. Well recovery is affected by well casing, borehole radii, screened length, hydraulic conductivity, and specific storage of porous media. In this study, a new slug tests model was developed through finite element approximation and the validity and usefulness of the model were tested in various ways. Water level fluctuation in a well under slug test and cons-equent groundwater flow in the surrounding porous medium were appropriately coupled through estimation of well-flux using an iteration technique. Numerical accuracy of the model was verified using the Cooper et al. (1967) solution. The model has advantages in simulations for monitored slug tests, partial penetration, and inclusion of storage factor. Volume coverage of slug tests is significantly affected by storage factor. Magnitude and speed of propagation of head changes from a well increases as storage factor becomes low. It will be beneficial to use type curves of monitored head transients in the surrounding porous formation for estimation of specific storage. As the vertical component of groundwater flow is enhanced, the influence of storage factor on well recovery decreases. For a radial-vertical flow around a partially penetrated well, deviations between hydraulic estimates by various methods and data selection of recovery curve are negligible on practical purposes, whereas the deviations are somewhat significant for a radial flow.

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Theoretical analysis of erosion degradation and safety assessment of submarine shield tunnel segment based on ion erosion

  • Xiaohan Zhou;Yangyang Yang;Zhongping Yang;Sijin Liu;Hao Wang;Weifeng Zhou
    • Geomechanics and Engineering
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    • v.37 no.6
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    • pp.599-614
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    • 2024
  • To evaluate the safety status of deteriorated segments in a submarine shield tunnel during its service life, a seepage model was established based on a cross-sea shield tunnel project. This model was used to study the migration patterns of erosive ions within the shield segments. Based on these laws, the degree of deterioration of the segments was determined. Using the derived analytical solution, the internal forces within the segments were calculated. Lastly, by applying the formula for calculating safety factors, the variation trends in the safety factors of segments with different degrees of deterioration were obtained. The findings demonstrate that corrosive seawater presents the evolution characteristics of continuous seepage from the outside to the inside of the tunnel. The nearby seepage field shows locally concentrated characteristics when there is leakage at the joint, which causes the seepage field's depth and scope to significantly increase. The chlorine ion content decreases gradually with the increase of the distance from the outer surface of the tunnel. The penetration of erosion ions in the segment is facilitated by the presence of water pressure. The ion content of the entire ring segment lining structure is related in the following order: vault < haunch < springing. The difference in the segment's rate of increase in chlorine ion content decreases as service time increases. Based on the analytical solution calculation, the segment's safety factor drops more when the joint leaks than when its intact, and the change rate between the two states exhibits a general downward trend. The safety factor shows a similar change rule at different water depths and continuously decreases at the same segment position as the water depth increases. The three phases of "sudden drop-rise-stability" are represented by a "spoon-shaped" change rule on the safety factor's change curve. The issue of the poor applicability of indicators in earlier studies is resolved by the analytical solution, which only requires determining the loss degree of the segment lining's effective bearing thickness to calculate the safety factor of any cross-section of the shield tunnel. The analytical solution's computation results, however, have some safety margins and are cautious. The process of establishing the evaluation model indicates that the secondary lining made of molded concrete can also have its safety status assessed using the analytical solution. It is very important for the safe operation of the tunnel and the safety of people's property and has a wide range of applications.

Revalidation of Measuring Instrument Systems Thinking and Comparison of Systems Thinking between Science and General High School Students (과학 고등학교와 일반 고등학교 학생들을 대상으로 시스템 사고측정 도구의 타당도 검증 및 시스템 사고 비교)

  • Lee, Hyonyong;Lee, Hyundong
    • Journal of The Korean Association For Science Education
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    • v.33 no.6
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    • pp.1237-1247
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    • 2013
  • The purposes of this study are 1) to revalidate the developed Measuring Instrument Systems Thinking and 2) to compare systems thinking skills between gifted and non-gifted high school students. For the test, 116 gifted science students and 553 non-gifted students were sampled from high schools. Exploratory factor analysis and confirmatory factor analysis were performed and Independent t-test was performed using the average of the two groups. The finding of the exploratory factor analysis indicated 5 factors in the model with 4 items per single factor. The result of confirmatory factor analysis was generally appropriate and acceptable (5 factor model: ${\chi}^2/df$ : 2.765, TLI=.907, CFI=.929, IFI=.930, RMSEA=.044). The reliability for 20 items turned out to be high because the Cronbach's alphas were at .875 and .693~.751 per each factor. In addition, the result of t-test showed that systems thinking skills among gifted science students were significantly higher than non-gifted students. This study could be expanded to measuring systems thinking with qualitative research tools and to various school levels.

The Infuence of Venture Club Activity by University Student's Goal-Oriented Behavior Model on Self-determination and Startup Intention: Focused on the Medaiation Effects of Big 5 (벤처동아리활동 대학생의 목표 지향적 행동모델이 자기결정성 및 창업의지에 미치는 영향: 성격 5요인의 매개효과)

  • Park, Hwa Soon;Byun, Sang Hea
    • Asia-Pacific Journal of Business Venturing and Entrepreneurship
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    • v.16 no.2
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    • pp.79-93
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    • 2021
  • The question of why do you want to start a "start?" Is the most basic step in trying to do something. In other words, previous studies have shown that the degree of confidence in an individual's decision affects the setting of a specific purpose. Based on this, this study aims to provide basic data for deriving the direction of entrepreneurship education in college students by analyzing the effects of goal-oriented behavioral model on college students' self-determination and intention to start a business through the 5 factor model. To achieve the purpose of the study, a self-report questionnaire was conducted from October 01 to November 11, 2019 for university students attending located in Gyeonggi-do, Seoul. A total of 150 questionnaires were distributed, and 125 parts were used for the final analysis, except 25 parts with insincere responses or errors. Data were analyzed using SPSS Win 24, and reliability, validity analysis, frequency analysis, One-way ANOVA and regression analysis were performed, and three-step regression analysis and Sobel verification were performed for mediating effects. The summary of the study is as follows. First, the influence of university students' goal-oriented behavioral model on self-determination showed that attitudes, subjective norms, and perceived behavioral controls had statistically significant positive effects, and positive and negative expectations were statistically significant. Did not affect. Therefore, the higher the attitude, subjective norms, and perceived behavioral control, the higher the university students' self-determination. Second, the influence of college students' goal-oriented behavioral model on the intention to start a business was as follows.). As a result, the higher the perceived behavioral control and positive expectation, the higher the intention to start up. Third, regression model 1 showed that the behavioral control and positive expectation sentiment among the goal-oriented behavioral model had a significant positive influence on the college students' intention to start a business. Affected. Regression model II added the parameters of the 5 factor model, which increased 2.5% of explanatory power than the first regression model. Perceived behavioral control and positive expectations had a statistically significant positive effect, negative expectations had a statistically significant negative effect, and among the 5 factor model, openness had a statistically significant positive (+) Affected. From these results, it can be seen that the Big Five personality factors have a mediating effect on the relationship between goal-oriented behavior model and intention to start up. This study confirmed that the goal-oriented behavioral model of college students is an important variable in implementing self-determination and intention to start a business. In addition, by using his Big 5 personality factors as positive feedback, he has proved to play an important role by identifying the mediation role that can be set, planned and utilized to plan and achieve his life. The result of this study is that college students are interested in the intention of individual start-ups, so they are not freed from difficult employment difficulties. It is intended to provide basic data useful in the age of creation of government.

Proposal for the Estimation Model of Coefficient of Permeability of Soil Layer using Linear Regression Analysis (단순회귀분석에 의한 토층의 투수계수산정모델 제안)

  • Lee, Moon-Se;Ryu, Je-Cheon;Lim, Heui-Dae;Park, Joo-Whan;Kim, Kyeong-Su
    • The Journal of Engineering Geology
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    • v.18 no.1
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    • pp.27-36
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    • 2008
  • To derive easily the coefficient of permeability from several other soil properties, the estimation model of coefficient of permeability was proposed using linear regression analysis. The coefficient of permeability is one of the major factors to evaluate the soil characteristics. The study area is located in Kangwon-do Pyeongchang-gun Jinbu-Myeon. Soil samples of 45 spots were taken from the study area and various soil tests were carried out in laboratory. After selecting the soil factor influenced by the coefficient of permeability through the correlation analysis, the estimation model of coefficient of permeability was developed using the linear regression analysis between the selected soil factor and the coefficient of permeability from permeability test. Also, the estimation model of coefficient of permeability was compared with the results from permeability test and empirical equation, and the suitability of proposed model was proved. As the result of correlation analysis between various soil factors and the coefficient of permeability using SPSS(statistical package for the social sciences), the largest influence factor of coefficient of permeability were the effective grain size, porosity and dry unit weight. The coefficient of permeability calculated from the proposed model was similar to that resulted from permeability test. Therefore, the proposed model can be used in case of estimating the coefficient of permeability at the same soil condition like study area.

Social Network Changes of pre- and post- Retirement (중·노년기 은퇴자의 은퇴 전후의 사회적 관계망 변화)

  • Park, Hyunchun;Hong, Jin Hyuk;Choi, Minjae;Kwon, Young Dae;Kim, Jinseok;Noh, Jin-Won
    • The Journal of the Korea Contents Association
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    • v.14 no.12
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    • pp.753-763
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    • 2014
  • After retirement, retirees are exposed to many changes. But, one of the most influential factor on retirement is Social network. Social network is making various relationships with many people. This consists of functional feature and structure feature. This study to systematically investigate social network changes of pre- and post-retirement by using two features. We utilized 2008~2012 'Longitudinal study of ageing' and selected 1,569 retirees above 45 years old as a final subject. This study used STATA 12.0 program for analysing frequency and descriptive statistic. At first, we analyzed personal characteristics and affecting factor on social network of retirees through Panel logit model and fixed effects regression model. Second, we applied multiple panel logit model and fixed effects model to learn factor affecting employment and social network changes. We found that a number of social activities affects social network in the structure feature and support from sons and daughters also influences social network in the functional feature after retirement.

An Evaluation Model for the Major Science Research Facilities and Equipments to Enhance the Competitiveness of the Science and Technology: A Focus on the Test of Reliability and Validity of the Model (과학기술 경쟁력 제고를 위한 대형연구시설 및 장비 평가모형 분석 : 모형의 신뢰성 및 타당성 검토를 중심으로)

  • Kwon, Gi-Heon;Cha, Yong-Jin;Lee, Hong-Jae
    • Journal of Korea Technology Innovation Society
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    • v.10 no.1
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    • pp.121-142
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    • 2007
  • The purpose of this study is to construct the evaluation model for the major science research facilities and equipments to enhance the competitiveness of the science and technology and also to test the reliability and validity of the model. To achieve the purposes, this study theoretically reviews the concept of the major science research facilities and equipments and their characteristics. Through a review of literature, this study draws 11 criteria for evaluating the priorities of the major science research facilities and equipments. These criteria are categorized as two dimensions - 'science & technology' and 'national policy'. The dimension of science & technology includes scientific importance, technological readiness, utilization rate, common utilization rate, and ability of management and operation. The national policy dimension contains degree of correspondence with national science development, imperativeness of national policy, science and technical effectiveness, economic and industrial effectiveness, responsiveness of research demand, and equity among the related institutions. The competitiveness of the science and technology consists of these two dimensions. The evaluation model is established on the framework of criteria. The 18 major science research facilities and equipments are selected through a series of Delphi. The survey of experts (BT, ET, IT, NT and ST) is also implemented to evaluate the 18 major science research facilities and equipments by 11 criteria. The overall results indicate that the reliability and validity of the model are good. The reliability tests show that the five indicators of science & technology and the six indicators of national policy have high internal consistencies. The confirmatory factor analyses reveal that the two constructs - 'science & technology' and 'national policy' - have high convergent and discriminant validity. The correlational analyses also show that the criteria-related validity between them is high. Furthermore, the results of higher order factor analysis indicate that the fit indices of the model are high and suggest a good fit to the data. Based on these findings, the policy implications of the model are discussed.

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Development of the Performance Measurement Model of Electronic Medical Record System - Focused on Balanced Score Card - (균형성과표를 활용한 전자의무기록시스템의 성과측정 모형개발)

  • Lee, Kyung Hee;Kim, Young Hoon;Boo, Yoo Kyung
    • Korea Journal of Hospital Management
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    • v.21 no.4
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    • pp.1-12
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    • 2016
  • The purpose of this study are suggest to performance measurement model of Electronic Medical Record(EMR) and Key Performance Index(KPI). For data collection, 665 questionnaires were distributed to medical record administrators and insurance reviewers at 31 hospitals, and 580 questionnaires were collected(collection rate: 87.2%). Regarding methodology, Critical Success Factor(CSF) and index of the information system were derived based on previous studies, and these were set as performance measurement factors of EMR system. The performance measurement factors were constructed by perspective using BSC, and analysis on causal relationship between factors was conducted. A model of causal relationship was established, and performance measurement model of EMR system was proposed through model validation. Analysis on causal relationship between performance management factors revealed that utility cognition of the learning & growth perspective factor had causal relationship with job efficiency(${\beta}=0.20$) and decision support(${\beta}=0.66$) of the internal process perspective factors, and security had causal relationship with system satisfaction(${\beta}=0.31$) of the customer perspective factor. System quality had causal relationship with job efficiency(${\beta}=0.66$) and decision support(${\beta}=0.76$) of the internal process perspective factors, all of which were statistically significant(P<0.01). Job efficiency of the internal process perspective had causal relationship with system satisfaction(${\beta}=0.43$), and decision support had causal relationship with decision support satisfaction(${\beta}=0.91$) and job satisfaction (${\beta}=0.74$), all of which were statistically significant(P<0.01). System satisfaction of the customer perspective had causal relationship with job satisfaction(${\beta}=0.12$), job satisfaction had causal relationship with cost reduction(${\beta}=0.53$) of the financial perspective, and decision support satisfaction had causal relationship with productivity improvement(${\beta}=0.40$)of the financial perspective(P<0.01). Also, cost reduction of the financial perspective had causal relationship with productivity improvement(${\beta}=0.37$), all which were statistically significant(P<0.05). Suitability index verification of the performance measurement model whose causal relationship was found to be statistically significant revealed that $X^2/df=2.875$, RMR=0.036, GFI=0.831, AGFI=0.810, CFI=0.887, NFI=0.838, IFI=0.888, RMSEA=0.057, PNFI=0.781, and PCFI=0.827, all of which were in suitable levels. In conclusion, the performance measurement indices of EMR system include utility cognition, security, and system quality of the learning & growth perspective, decision support and job efficiency of the internal process perspective, system satisfaction, decision support satisfaction, and job satisfaction of the customer perspective, and productivity improvement and cost reduction of the financial perspective. In this study, it is expected that the performance measurement indices and model of EMR system which are suggested by the author, will be a measurement tool available for system performance measurement of EMR system in medical institutions.

A Development of 3-D Numeric Model for the Confined Flow and Discharge under Sea Ground (해저 지중 피압유체의 흐름과 양수량 산출에 관한 3차원 수치모형의 개발)

  • Kim, Sang-Jun
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.22 no.6
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    • pp.387-396
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    • 2010
  • A 3-D numeric model for the confined transient flow under sea ground have been developed. This is FDM model using Gauss-Seidel SOR (successive over-relaxation). This model shows the similar head distribution pattern to Theis analytic solution and MODFLOW simulation. The input flowrate to the aquifer and discharge of well have been compared. And it have been found that mass balance is influenced by the weight factor ${\alpha}$, i.e. fullyimplicit method (${\alpha}$=1) shows 5% error, but when ${\alpha}$ becomes to 0.5(Crank and Nicolson method) the mass balance becomes worse and the model result diverges. And the convergency of the model is not much different when $\lambda$ (over-relaxation factor)=0.8~1.5, but when $\lambda$>1.5, the model result diverges. The test-run shows that the well discharge becomes smaller when another well is near. This model can cover the isotropy$(Kx{\neq}Ky{\neq}Kz)$ and inhomogeneity, and can be used for the selection of well site, discharge calculation, and head prediction in case of the artificial recharge etc.

Structural Equation Modeling on Case Management Outcomes and Factors Influencing Outcomes in the Community-dwelling Vulnerable Elders (취약계층 재가노인의 사례관리 성과와 영향요인에 관한 구조모형 구축)

  • Moon, Hyunjung;Lee, In-Sook
    • Journal of Korean Academy of Nursing
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    • v.43 no.6
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    • pp.791-800
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    • 2013
  • Purpose: This study was done to test a structural equation modeling of case management outcomes in order to identify parameters affecting case management outcomes for the community-dwelling vulnerable elders. Methods: Data were collected from 309 nurses (case managers) and community-dwelling vulnerable elders (clients) from public health centers. For data analysis, descriptive statistics, Pearson correlation analysis, factor analysis, and covariance structure analysis were performed using SPSS Version 18.0 for Windows and Amos 16.0. Results: The hypothetical model had an acceptable fit: GFI=.97, CFI=.95, RMSEA=.02, SRMR=.05. The factor "case managers' singularity" had the greatest impact on case management outcomes in this model. In addition, the factor "case management practice" influenced case management outcomes; however, client characteristics did not. Case managers' singularity affected case management outcomes directly and indirectly, with case management practice mediating the latter effect. Conclusion: These results suggest that the causal relationship between case management outcomes and factors influencing these outcomes should be clarified through longitudinal research including a variety of client characteristics. In addition, in future studies, analysis of the effects of programs to improve manpower quality and examine the relationships among case management outcomes should be done.