• Journal of the Korean Geotechnical Society
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• v.33 no.3
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• pp.49-62
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• 2017

In order to understand response of geo-structures to the freezing-thawing process in the ground, it is necessary to consider phase change of the pore water of the ground and also to understand soil interaction with structures. In this study, numerical analysis was carried out for freezing and thawing effect on the modular road system. Neumann's theoretical equation for freezing-thawing processes in porous media can be used to estimate frozen depth and heaving from basic soil properties and ground and surface temperature, but its application is limited to the case for the sediment with fully saturated condition and zero unfrozen water content. Numerical analysis of the modular road system was performed on various soil types and different ground water table as the varying freezing index. The amount of heaving in the silty soil was much larger than those in granite weathered soil or sandy soil, and lowering groundwater level reduced ground heaving induced by freezing. Numerical analysis for temperature history of the ground surface predicted residual heaving near the surface by the freeze-thaw process in silty soil. It ought to reduce stiffness and bearing capacity of the ground so that it will impair stability and serviceability of new road system. However, the amount of residual heaving was insignificant for the road system installed in weathered soil granite and sandy soil. Since modular road system is a pavement structure mounted on the supporting substructure unlike the prevalent road pavement system, strict criteria should be applied for uniform and differential settlement of the pavement system.

• Journal of the Korean Geotechnical Society
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• v.34 no.3
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• pp.29-41
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• 2018

In the case of the enlargement levee on the soft foundation, the existing levee and the enlargement levee connection can be damaged due to heterogeneous subsidence such as differential settlement at the joint of the box culvert passing through the levee. This study selected the downstream region of the Geum River and then confirmed the influence of the piping possibility on the levee by performing a 2D seepage analysis and analyzing the seepage tendency according to the position of the box culvert's gate. As a result, the flow velocity and the hydraulic gradient are larger in the upper breakage than the lower breakage, and the upper leak was more vulnerable to the piping than the lower leak. If leaks occur in the gate located on the riverside land, the risk of piping is increased when the water level rises and is maintained highly. In the case of the gate located on the inland, it could be predicted that the leakage could damage the stability of levee by increasing the water pressure inside the levee. As a result, if leakage occurs at any position in the box culvert, the pore water pressure is increased or decreased compared with the case when no leakage occurs. Therefore, if the pore water pressure is drastically reduced or increased compared with the normal case, leakage may occur. However, the result of this study is based on a 2D seepage analysis, and it is likely to be different from actual cases. Therefore, more detailed analysis by 3D analysis is recommended.

• Journal of Environmental Science International
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• v.20 no.1
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• pp.137-146
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• 2011

In this research, food waste source reduction model for apartment was investigated. In spite of prohibition of direct landfill of food waste and continuous efforts made by government and local government, food waste production increases steadily. Recycling ratio of the food waste increases every year, but its products have many problems like low quality, stability, salt, odor etc. Household occupies 63.3% of whole food waste production and this is subject to be a key factor to control food waste. We surveyed S apartment in Kwangju city as a model case, in which administrative office and women's association adopted clean plate eating, separation of raw food waste and earth worm composting as a series of method for source reduction and recycling inside the apartment. With the help of residents' participation and practice, food waste production decreased 15.6% from 0.31 g/capita/day in 2007 to 0.26 g/capita/day in 2009 (domestic average 0.30 g/capita/day). Separation of raw food waste and its composting using earth worm were very effective, and were subject to resolve the problems of present food waste treatment technologies. And earth worm composting was very useful in environmental, economical, societal and educational aspects. Instead of economical incentive, educational programs about food value, environmental problem and critical method for food waste separation were more effective for promotion of source reduction. From the analyses on the process and success factors in this model, we could conclude that leader's role was one of the key factors for the settlement of source reduction, and that was to understand the seriousness of the food waste and to seek solution, to test techniques, and to practice by oneself. Furthermore, networking and collaboration among residents, local government, NGO and local press promoted residents' participation, and it was through various education and investigation. Finally, source reduction and self recycling model of food waste in the apartment, that applies separating raw food waste and earth worm composting based on the collaboration among residents, local government, NGO, and local press, should be disseminated, and environmental policy also should be changed to make it possible.

• Journal of the Korean GEO-environmental Society
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• v.10 no.3
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• pp.21-28
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• 2009

As the natural aggregates such as sand and clay are getting exhausted, the quantity of utilizing geosynthetics is being increased in the solid waste landfill. Especially, the waste landfills have been constructed at the gorge in the mountainous area and reclaimed land from the sea in the Korean Peninsula. Those areas are not favorable for construction of waste landfill in geotechnical engineering aspect. In this study, the frictional characteristics of geosynthetics that used in the waste landfill were estimated. Then, the studies of the behavior of geosynthetics and stability of LDCRS (Leachate Detection, Collection, and Removal System) of side slope were conducted in the waste landfill by means of the pilot test, and numerical analysis. Geocomposite which is combined type or separated type is influenced on the strain itself, and also implicated in the stress and strain of geomembrane at the lower layer. The strain on the combined type of geocomposite is about 50% smaller than that of the separated type at the side slope. The lateral displacement and settlement of top at the slope with the separated type are three times greater than that of the combined type. In the numerical analysis, discontinuous plans in between ground and geosynthetic, geosynthetic and geosynthetic, goesynthetic and waste have been modeled with the interface element. The results gave a good agreement with the field large-scale model test. The relative displacements of geosynthetics were also investigated and hence the interface modeling of liner system is appropriate for analysis of geosynthetics liner system in the waste landfill.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.567-573
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• 2020

This study was done to develop indicators for cities that can be used in the long term and in a sustainable manner. Activation indicators were developed to improve the resilience in the downtown area of Seo-gu, Incheon. Preliminary indicators were derived from prior studies on similar indicators of resilience for urban regeneration, and an expert opinion survey was conducted to analyze the suitability and importance of the indicators. Activation indicators were established for improving urban resilience in six areas: population stability, social inclusion, industrial diversity, local productivity, environmental sustainability, and social-based convenience. From 60 preliminary indicators, 42 indicators were selected through the expert opinion surveys for securing an economically active population, establishing a living infrastructure, improving the settlement environment, and upgrading industry to reflect the characteristics of the West, including industrial complexes. It was found that diversification is necessary. Further study is still necessary to improve the objectivity of the indicators and calculate a resilience index. The significance of this study is that it looks at quantitative indicators, complements other studies on regional decline diagnosis, and presents realistic alternatives suitable for domestic situations based on the concept of resilience.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.5
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• pp.787-799
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• 2017

Although the long-term leakage between the box culvert and the soil contact surface is one of the main causes of the failure in the embankment of the reservoir, there is a little studies on this matter. If a leakage occurs by the structure such as the buried box culvert of reservoir embankment is partially damaged, it is difficult to observe and there is a possibility of damage caused by piping. For these reasons, more research is necessary. In this study, the embankment type of the reservoir is divided into the core type and the homogeneous type when the damaged box culvert passing through the embankment of the reservoir is leaked due to the differential behavior of materials like differential settlement. In view of the condition, the seepage analysis of 2D was performed according to the water level change. The result of the study shows that the possibility of piping increases at the upper part rather than the bottom part of the box culvert when the leakage occurs to the box culvert passing through the embankment of the reservoir. Particularly, it is considered that the presence of the core helps to maintain the seepage stability of the embankment in case where the leakage occurs at the downstream side of the embankment. Also, if there is a drastic decrease on the internal pore water pressure in the embankment of reservoir, it is necessary to consider the possibility of piping.

• Journal of the Korean Geosynthetics Society
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• v.19 no.1
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• pp.75-82
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• 2020

There have been often cases of collapse for geogrid reinforced soil (GRS) retaining wall. Hence, social interest in the reinforcement and restoration of the collapsed GRS wall is increasing day by day. However, there are only few researches. For this reason, a series of numerical analyses using the Plaxis 2D program was conducted in this study to analyze the suitable reinforcement methods that can be applied on the existing damaged GRS wall caused by overturning of the modular blocks facing and the surface settlement at the backfill as the results from the design failure. The restoration plan used in this study is composed of two cases: (Case 1) soil nailing reinforcement and reinforced concrete (RC) wall facing construction on the existing damaged GRS wall; and (Case 2) removal of the entire damaged GRS wall and then reconstruction. The results on the internal stability of the GRS wall show that Case 1 obtained a greater safety factor than Case 2 for tensile force while Case 2 had a greater safety factor than Case 1 for pullout failures. Case 1 was found to be more stable than Case 2 in terms of the global slope safety by shear strength reduction method and the external deformation behavior by numerical analysis. In this study, the existing damaged GRS wall which was reinforced using Case 1 method shows more stable external behavior.

• Korean Journal of Social Welfare
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• v.57 no.4
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• pp.225-251
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• 2005

This study examines the changing paradigm of family welfare policy and tries to find an appropriate model for the delivery system of family welfare service. First, the study reviews the contexts of family policy in new paradigm, and traces the changing process of family welfare-related administration from the ministry of human and health to the ministry of family and gender equality. Second, the study examines the principles of the delivery system for family welfare service to pursue the advancement of family policy. In conclusion, it proposes an alternative model for the successful settlement into community of family welfare delivery system, and a desirable position and role of family support center. The principles of the delivery system of family welfare service is fundamentally to make family policy come realistic, such as strengthening family stability through the harmonic reconciliation of work and family, preventing any forms of families from social safety net, and securing happy lives. Comprehensiveness, continuity, effectiveness, and accessibility of the system are also needed. In particular, family support center, recently very controversial, could be better as a representative council of networking various kinds of community organizations in the fields of family welfare enhancement, rather than organization of direct service provision, such as family counselling, education and therapy. Finally, an alternative model of delivery system for family welfare service is presented.

• Journal of the Korean GEO-environmental Society
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• v.9 no.4
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• pp.23-36
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• 2008

Soil nailing system can be mentioned to a method of supporting as the shear strength of in-situ soils is increased by passive inclusions. In the general soil nailing system, facing walls are used in two kind of a lattice concrete block or a cast in placed concrete wall. A case of lattice concrete blocks is used in slow slopes greater than 1(V):0.7(H). Also, a case of a cast in placed concrete wall is used in steep slopes less than 1(V):0.5(H). The cast in placed concrete walls are constructed to 30 cm thick together with a shotcrete facing. In this study, the assembling soil nailing method as a new soil nailing system will be proposed. This method is assembly construction using precast concrete panels with 20 cm thick. So, the ability of construction and the quality of facings can be improved more than a conventional soil nailing system. This method can be obtained the effects that a global slope stability increase, as precast concrete panels are immediately put on cutting face after excavating a slope. In this study, confining effects of concrete panels using the assembling soil nailing system were found out by large scaled load tests. In the tests, the load-settlement relationship to an assembling soil nailing system due to the stiff facings as concrete panels appeared to be better than a typical soil nailing system with shotcrete facings.

• Journal of Korean Elementary Science Education
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• v.18 no.1
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• pp.19-28
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• 1999

This study aims to analyze tile research trends of science education in Korea, and suggest the direction of the desirable research, which is to help the improvement of science education practically. To achieve these aims, the papers related to the science education (paper;1288, master′s thesis;724, doctoral thesis;59), which were published from 1992 to 1996 in Korea, are classified by the criteria for the analysis and summed up. The condensed results of this study are as follows, 1. The papers published through this period, maintains the stability in aspect of quantity compared with 1980s. It is owing to the efforts of the prime investigator so that "the science education," as a part of normal science, may settle down in Korea. 2. In the case of thesis for the academic degree, the doctoral theses are rare, as the ratio of the doctoral vs. the master′s is 1:13. Even so, most of the theses were produced by a few universities(master′s thesis/Kor. Nat. Univ. of Edu.;28.3%, Ewha Woman′ Univ.;16.2%, doctoral thesis/Seoul Nat. Univ.;57.6%, Kor. Nat. Univ. of Edu.;22.0%). 3. Most of papers are preponderant at three categories among the ten categories proposed by this study (science teaching-learning material;23.5%, science teaching methods;21.4%, psychology of science education;21.1%). 4. Concerning the subject of research, these papers are not diversity and intensive, that is; the subject related to scientific concepts, scientific thinking and attitude, and analysis of scientific textbook is 17.7%, 14.3%, and 10.5% of the total, respectively. 5. Though not including this study, among the theses for the master of science education, many of theses are related to the subject of pure science. There are some suggestions related to tile results of this study. The severe preponderance ill the training process, the subject, and area of research, can be pointed out one of the flimsy in our researches of science education. Because these cannot be considered separately, the policy and support of educational administration must be needed to remove this phenomena. To improve the present situation of science education, the research funds have to be given to the practical than the theoretical subjects. Which can make promptly a settlement of tile problems and difficulties from the field of science education, and encourage the reseal,:h activities that tile front teachers take part in. Lately, the accumulation of literature and references are a prior condition in the development of academic knowledge. Therefore the data base system for the information of science education and translation of foreign literature related to science education must be achieved. In addition, the programs that tile teacher and the investigator can make good use of such an information without limited conditions, must be prepared.