• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6B
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• pp.507-514
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• 2011

A numerical model has been developed by employing a finite element method to simulate the depth-averaged 2-D dispersion of the heat pollutant, which is an important pollutant material in natural streams. Among the finite element methods, the Streamline Upwind/Petrov Galerkin (SUPG) method was applied. Also both linear and quadratic elements can be applied so that irregular river boundaries can be easily represented. To show the movement of heat pollutants, the reaction term describing heat transfer was represented as an equation in which sink/source term is proportional to the difference between the equilibrium temperature and water surface temperature. The equation was expressed so that the water surface temperature changes according to the temperature transfer coefficient and the equilibrium temperature. For the calibration of the model developed, analytic and numerical results from a case of rectangular channel with full width continuous injection have been compared in a steady state. The comparisons showed that the numerical results were in good agreement with analytical solutions. The application site was selected from the downstream of Paldang dam to Jamsil submerged weir, and overall length of this site is about 22.5 km. The change of water temperature caused by the discharge from the Guri sewage treatment plant has been simulated, and results were similar to the observed data. Overall it is concluded that the developed model can represent the water temperature changes due to heat transport accurately. But the verification using observed data will further enhance the validity of the model.

• Geophysics and Geophysical Exploration
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• v.16 no.3
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• pp.154-162
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• 2013

Vertical electrical sounding and 2D electrical resistivity survey were applied for evaluating the characteristics of alluvial layers at a groundwater artificial recharge site. The fine particles in alluvial layer, main target layer of groundwater artificial recharge, may cause clogging phenomena. In this case, electrical resistivity method is an effective technique to verify the spatial distribution of low-resistivity layers, such as saturated silts and clays. On the other hand, much attention should be paid to interpret the resistivity data in unconsolidated layers, because thick clayey overburden sometimes produces a masking effect on underlying interbedded resistive sands and gravels. Considering these points, we designed 35 points arranged in a grid form for vertical electrical sounding and 10 lines for 2D electrical resistivity survey, and concentrated our effort on enhancing the vertical and horizontal resolution of resistivity images. According to the results, 15 meters thick layers consisting of sands and gravels are located in 30 meters below ground. And the spatial distribution of silts and clays are mapped, which may cause clogging. Consequently, this approach can contribute to design and determine the location and depth of injection and observation wells for groundwater artificial recharge.

• Journal of the Korean Society of Earth Science Education
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• v.4 no.3
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• pp.278-296
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• 2011

The purpose of this study is to examine the pedagogical content knowledge (PCK) elements and the changes in the science lesson planning and implementation difficulties experienced by high-career elementary school teachers with over 20 years of educational experience through the instructional consulting case of the Seoul City Office of Education Scholarship Support Group in order to find implications on effective instructional consulting support plan for improving the science teaching professionalism of high-career elementary school teachers. The result of this study is as follows : First, the pedagogical content knowledge (PCK) elements on the science lesson planning and implementation difficulties experienced by high-career elementary school teachers with over 20 years of educational experience were related to teaching strategy and they experienced difficulties in lesson content organization using lesson model and experiment facilitation and questioning, as well as in the area of interest and motive management that are definitional characteristic of learner in the learner element. Second, as for the changes in the PCK through science instructional consulting, they recognized the importance of the designing and experimenting process as students become the subject in the experiment facilitation in lesson, and they ended up attempting the postscript for promoting the thinking power of students. In addition, it was found that not only the cognitive characteristic but also the definitional characteristic of learner is important in science lesson and that students' motive is also an element that needs to be continuously managed. Third, as for effective instructional consulting plan for enhancing the science teaching professionalism of high-career elementary school teachers, it was revealed that it is necessary to first develop lesson expertise improvement consulting program that takes into account of teaching profession advancement phase of high-career teachers, and establish instructional consulting system and human resource pool of high-quality consultants based on the administrative and financial support from the Office of Education. The academic significance of this study is in the fact that it examined and searched for support plan on science teaching professionalism of high-career elementary school teacher, but a more extensive and in-depth study is needed since there is a limitation in this study on the object of study and the period.

• Journal of Korea Water Resources Association
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• v.45 no.3
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• pp.317-329
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• 2012

It is increasing to make an efforts on preventing natural river environment and preserving natural river ecosystem as development is unavoidable. In the case of inconsistent river flow caused by reservoir development, fishway is an alternative to secure fish diversity and preserve existing river ecosystem but existing fishway was established without full study for their functions. In this study, hydraulic characteristics of natural fishway established on Beakje weir's right side were analyzed. The results show that the fishway has reasonable depth and velocity condition which inhabit condition is enough for a dominant species. For assessing the optimal design of fishway, the Weighted Usable Area (WUA) was calculated by using two dimensional numerical model under the ordinary flow condition. The comparison results for various pool widths in the fishway show that the designed width has maximum WUA for adult Zacco platypus but WUA is maximized with 1m wider pool width than designed width for spawning.

• Korean Journal of Environment and Ecology
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• v.25 no.6
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• pp.846-852
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• 2011

This study researched the spawning sites of Kaloula borealis in a large number of wetlands in Jeju Island between May and August from 2007 to 2010. Based on the surveys, we discovered the locations of their habitats by investigating their calls from a rainy night to the next day and where their spawning sites were by ascertaining the existence of their eggs and tadpoles. According to the results, 83 wetlands were used as spawning sites across Jeju Island. A large number of wetlands were found to be permanent wetlands for Kaloula borealis. In addition, 81.9% of the wetlands in Jeju Island were found to be at an altitude of 150m or lower, and they spawned in shallow water not more than 50cm in depth. By region, 54 wetlands were in Jeju-island 29 wetlands were in Seogwipo-si. One of the reasons that Seogwipo-si has less wetlands than Jeju-si is that there are more orchards in Seogwipo-si than Jeju-si; accordingly, wetlands in Seogwipo-si were found to be more destroyed by farming. In the case of Seongsan-eup, a reedy marsh stretches out widely so that spawning sites were well preserved compared to other regions. This research will provide useful data for sustaining the population of Kaloula borealis by protecting their spawning sites from development, by offering habitats, and restoring spawning sites, which have become severely damaged and destroyed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.4
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• pp.75-86
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• 1985

A beam with web opening may reduce the cost of steel and the height of multistory steel buildings. Bower's analysis based on the theory of elasticity and Vierendeel analysis had evaluated the normal stresses around the holes, but these analyses have difficulties for practical uses because of complexity and the limitation for their application. In this study, it is shown that the finite element method, using smaller number of isoparametric elements by taking only a part of the beam which includes the hole, can diminish defects of the above two methods and it may represent more satisfactorily the distribution of the local stress concentration around the hole than the other methods which employed linear elements such as in the analysis by Samuel or Redwood. This study presents the effects of moments, shears, and eccentricities of a hole on the distribution of the normal stresses calculated by using the proposed finite element method. Consequently, it is found that the variations of shear force and hole depth give significant effects on the normal stresses around a hole, while the variations of eccentricities of the hole provide a little effect on them. The regression coefficients resulted from the multiple linear regression may be used for estimating the normal stresses around any arbitrary hole in the web of a beam, since the normal stresses guessed by this regression coefficient equation match well the results by the finite element method except the case of large eccentricity.

• Journal of The Korean Association For Science Education
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• v.40 no.3
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• pp.347-358
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• 2020

He purpose of this study is to design and apply a pilot assessment tools for scientifically gifted and talented elementary school students with lower grades. The assessment tool consists of three parts: homeroom teachers' recommendation, paper and pencil test and performance tests. The tools are verified whether they are suitable for unique characteristics of young children and enable to attract active participation. For suitability check, students' performance tests were inductively analyzed and 30 behavioral patterns were shown which were included and partially exceeded the level of lower elementary students' performance expectation in NGSS. As a result, we concluded that assessment tool developed in this study will be effective in discriminating young pupils' scientific talents. Then for participation check, we compared the number of coding references as an indicator of participation. Two cases were found that students with high interest participated passively in performance tests. We found these 'passive participants' had excessive scientific experiences and extremely narrow region of interest, during the process of complex interpretation between the results of this assessment tool and in-depth interviews with homeroom teachers. We found out in this study that newly developed tools can be used in school scene after modifying and elaboration through accumulation of more case studies.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.4
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• pp.32-49
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• 2010

Site characterization on geological and geotechnical conditions was performed for evaluating the earthquake ground motions associated with seismic site effects at a small urbanized area, Hongseong, where structural damages were recorded by an earthquake of magnitude 5.0 on October 7, 1978. In the field, various geotechnical site investigations composed of borehole drillings and seismic tests for obtaining shear wave velocity profile were carried out at 16 sites. Based on the geotechnical data from site investigation and additional collection in and near Hongseong, an expert system on geotechnical information was implemented with the spatial framework of GIS. For practical application of the GIS-based geotechnical information system to assess the earthquake motions in a small urban area, spatial seismic zoning maps on geotechnical parameters, such as the bedrock depth and the site period ($T_G$), were created over the entire administrative district of Hongseong town, and the spatial distributions of seismic vulnerability potentials were intuitively examined. Spatial zonation was also performed to determine site coefficients for seismic design by adopting a site classification system based on $T_G$. A case study of seismic zonation in the Hongseong area verified that the GIS-based site investigation was very useful for regional prediction of earthquake ground motions in a small urbanized inland area.

• Journal of Digital Convergence
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• v.16 no.5
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• pp.33-42
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• 2018

This paper is based on the suggestions of the prior research on the buyer feedback, the selection of various product options, and the payment procedure improvements for Korea ON-line E-Procurement System(KONEPS), and this is to confirm the necessity of improvement and satisfaction from the viewpoint of the workers of the public and subordinate organizations the purchasing and using of the computer equipment in the actual KONEPS(Korea ON-line E-Procurement System). Based on the basic questionnaires and in-depth interviews, this paper conducts the qualitative case studies on IT and non - IT workers who had purchasing experiences for equipment at public institutions and government agencies in Gyeongbuk province. As results of the study, it was confirmed that the improvement is necessary for the buyer feedback and option selection part, and that there is a difference among the work experience for the simplification of the payment procedure and the satisfaction. In addition, the biggest contribution in the provided research is to categorize and to analyze the opinions on the use of public and relevant subordinate research participants. Additional work will be needed for a large number of workers in public and subordinate organizations who have purchasing experiences for handling various procurement products and those working in the metropolitan area and other public and subordinate agencies.

• Journal of Digital Convergence
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• v.18 no.6
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• pp.167-175
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• 2020

The purpose of this paper is to provide directional and policy references to develop a higher level of service quality and consumer-oriented e-commerce platform. This paper has established a model of consumer behavior of Chinese fresh agricultural e-commerce using customer satisfaction theory and cognitive value theory, and used survey and SPS23.0 to verify hypothesis. Studies have shown that when consumers consume fresh agricultural products, product quality, logistics and distribution service quality, interactive quality of e-commerce platform, and product price and cognitive value have a positive effect on consumer behavior. This study is meaningful in the study of consumer behavior of fresh agricultural e-commerce, and in the case of fresh agricultural e-commerce companies, consumer behavior can be understood. In the model constructed in this paper, the relationship between each influencing factor and consumer behavior is considered comprehensively, but the possible relationship between fine molecular factors has not been studied and analyzed. In the future learning process, it is necessary to make clear the characteristics and particularity of the industry, think about its influencing factors comprehensively and make in-depth analysis.