• Journal of the Korean Geotechnical Society
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• v.34 no.1
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• pp.47-57
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• 2018

In recent years, vertical extension remodeling of apartment building is considered as one of the efficient ways to broaden and enhance the utilization of existing buildings due to the rapid development of population and decrement of land resources. The reinforcement of foundation is of great importance to bearing the additional load caused by the added floors. However, because of the additional load, the carried load by the existing piles would be in excess of its allowable bearing capacity. In this study, a conceptual construction method called preloading method was presented. The preloading method applies force onto the reinforcing pile before vertical extension construction. The purpose of preloading is to transfer partial load applied on the existing piles to reinforcing piles in order to keep each pile not exceeding the allowable capacity and to mobilize resistance of reinforcing pile by developing relative settlement. The feasibility and effect of preloading method was investigated by using finite numerical method. Two simulation models, foundation reinforcement with preloading and without preloading, were developed through PLAXIS 3D program. Numerical results showed that the presented preloading method is capable of sharing partial carried load of existing pile and develops the mobilization of reinforcing pile's frictional resistance.

• Korean Journal of Environment and Ecology
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• v.17 no.3
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• pp.285-294
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• 2003

The purpose of this paper is to provide useful knowledge for recreation management in natural park(NP) by evaluating use suitability of recreation resource. We had obtained data through a questionnaire, which surveyed 385 visitors at 6 of the 73 NP in Korea in 2001, based on stratified sampling method. We have analyzed the data using the multiple regression method. We found that 1) in bivariate analysis, the relationships between use suitability and all the recreation resources are fairly high and statistically significant. The higher the degree of recreation resources, the higher the degree of use suitability. 2) in multivariate analysis, topography, social resource(SR), cultural resource(CR), landscape, smell, color and sound(SCS) have been turned out to be statistically significant at one percent level. 3) the direction of relationship between topography, SR, CR, landscape, SCS and use suitability is same. 4) in relative contribution of the use suitability of recreation resource, level of topography has been turned out to have about 1.05, 1.56, 2.16 and 2.70 times more important than that of SCS, SR, landscape, topography, respectively This results will be used for a criterion for recreation resource evaluation and a settlement of management priority and increasing user's satisfaction.

• Journal of The Korean Association of Information Education
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• v.22 no.1
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• pp.71-80
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• 2018

The purpose of this study is to analyze objectively the current state of preparation of SW education in Korea based on the survey of educational technology of elementary and secondary school which is investigated periodically every year. For this purpose, we extracted indicators related to SW education from educational technology level indicators such as human, material, and utilization and analyzed the change in the level of domestic educational technology level from 2014 to 2016. The main results of this study are as follows. Firstly, the ratio of teachers who have informatics teacher certificates among middle school informatics teacher is continuously decreasing from 2014(71%) to 2016(54%), and the number of information and the number of informatics teachers moving from informatics subject to other subjects is steadily increasing. On the other hand, there is a paradoxical situation in which the total number of teachers in informatics subject is continuously increasing for three years. Secondly, the total amount of ICT related budgets for elementary and secondary schools has been steadily decreasing since 2014. Thirdly, The ratio of informatics(computer) related creative activities in elementary schools dropped to 87.7% in 2015 and 84.6% in 2016. Also, the ratio of informatics subject operating school in middle school is gradually decreasing from 34.8% in 2014, 30.8% in 2015, and 28.2% in 2016. Based on the results of this analysis, this study suggested a method for stable settlement of SW education in elementary and secondary public education field.

• 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.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.3
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• pp.261-275
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• 2020

When excavating a small cross-section tunnel in a fault fracture zone using the shield TBM method, there is a high possibility of excessive convergence and collapse. Appropriate ground reinforcement is required to minimize construction cost loss and trouble due to a fault fracture zone. In this study, the optimal reinforcement area was suggested and the surrounding ground behavior was investigated through numerical analysis using MIDAS GTS NX (Ver. 280). For the parameters, the width of the fault fracture zone, the existence of fault gouge, and the groundwater level and depth of cover were applied. As a result, when there is not fault gouge, the convergence and ground settlement are satisfied the standard when applying ground reinforcement by up to 0.5D. And, due to the high permeability coefficient, it is judged that it is necessary to apply 0.5D reinforcement. There is a fault gouge, it was possible to secure stability when applying ground reinforcement between the entire fault fracture zone from the top of the tunnel to 0.5D. And, because the groundwater discharge occurred within the standard value due to the fault gouge, reinforcement was unnecessary.

• Journal of the Korean Geotechnical Society
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• v.34 no.11
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• pp.93-105
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• 2018

Precise investigation and interpretation of the ground subsidence risk factors needed to predict and evaluate the settlement problems of the surrounding ground due to the ground excavation. There are various geophysical exploration methods to investigate the ground subsidence risk factors. However, there are factors that influence the characteristics of the underground medium in these geophysical methods, and the actual soil contains complex factors affecting geophysical exploration. Therefore, it is necessary to analyze the effects on the geophysical methods based on the understanding of the geotechnical properties of soil. In this study, a test bed was constructed to consider various complicated factors in the complex ground and the ground behavior was analyzed by numerical analysis. In addition, we analyzed the limitations on investigating the ground subsidence risk factors through ground penetration radar (GPR) survey. As a result, ground subsidence of Open-cut Type Excavation is caused by various factors. Especially, in the case of soft ground condition, it was found that it was greatly influenced by the flow change of groundwater level. At the center frequency of GPR of 250 MHz, the attenuation of the electromagnetic wave is severely attenuated in the clay with high electrical conductivity, making it difficult to penetrate deeply into the ground (4 m below the surface). As the electromagnetic waves pass through the groundwater level below the groundwater, the attenuation of the electromagnetic waves becomes severe.

• Journal of the Institute of Convergence Signal Processing
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• v.22 no.4
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• pp.193-198
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• 2021

Recently, interests in the 4th industry have increased the level of demand for pest control by farmers in the field of rice farming, and the interests and use of agricultural pest control drones. Therefore, the diversification of agricultural control drones that spray high-concentration pesticides and the increase of agricultural exterminators due to the acquisition of national drone certifications are rapidly developing the agricultural sector in the drone industry. In addition, as detailed projects, an effective platform is required to construct large-scale big data due to pesticide management, exterminator management, precise spraying, pest control work volume classification, settlement, soil management, prediction and monitoring of damages by pests, etc. and to process the data. However, studies in South Korea and other countries on development of models and programs to integrate and process the big data such as data analysis algorithms, image analysis algorithms, growth management algorithms, AI algorithms, etc. are insufficient. This paper proposed an online drone pest control management information platform to meet the needs of managers and farmers in the agricultural field and to realize precise AI pest control based on the agricultural drone pest control processor using drones and presented foundation for development of a comprehensive management system through empirical experiments.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.559-575
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• 2021

Due to the increase in ground excavation work, the possibility of ground subsidence accidents is increasing. And it is very difficult to prevent these risk fundamentally through institutional reinforcement such as the special law for underground safety management. As for the various cases of urban ground excavation practice, the ground subsidence behavior characteristics which is predicted using various information before excavation showed a considerable difference that could not be ignored compared to the results real construction data. Changes in site conditions such as seasonal differences in design and construction period, changes in construction methods depending on the site conditions and long-term construction suspension due to various reasons could be considered as the main causes. As the countermeasures, the safety management system through various construction information is introduced, but there is still no suitable system which can predict the effect of excavation and risk assessment. In this study, a web-based system was developed in order to predict the degree of impact on the ground subsidence and surrounding structures in advance before ground excavation and evaluate the risk in the design and construction of urban ground excavation projects. A system was built using time series analysis technique that can predict the current and future behavior characteristics such as ground water level and settlement based on past field construction records with field monitoring data. It was presented as a geotechnical data visualization (GDV) technology for risk reduction and disaster management based on web-based system, Using this newly developed web-based assessment system, it is possible to predict ground excavation impact prediction and risk assessment.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.16 no.6
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• pp.107-117
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• 2021

The purpose of this study is to examine the causal relationship of related variables in order to promote entrepreneurship, which is one way to support the economic independence and stable settlement of North Korean defectors. This study is firstly to examine the influence of individualism and collectivism on entrepreneurial intentions, and secondly, to examine the mediating effect of social adaptability in the relationship between socialist value system and entrepreneurial intention. To this end, a survey was conducted on North Korean defectors, and the empirical analysis target was 223 North Korean defectors. For the verification of the causal relationship between personal disposition and entrepreneurial intention, and the causal relationship between value system and entrepreneurial intention PLS was used. And PROCESS for SPSS Macro was used to verify the mediating effect of social adaptation in the relationship between the value system and entrepreneurial intention. Looking at the results of the empirical analysis, the extraversion factor was found to have a positive effect on the entrepreneurial intention level of North Korean defectors, and the self-fulfillment desire factor was found to have a positive effect on the entrepreneurial intention. It was also found that individualist values have a positive effect on the entrepreneurial intentions of North Korean defectors, and collectivist values do not have a significant effect on the entrepreneurial intentions. As a result of examining the mediating effect of social adaptability between individualism/collectivism and entrepreneurial intention in this study, it was found that individualist value has a direct impact on entrepreneurial intention without engaging social adaptability.

• Journal of the Korean Geotechnical Society
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• v.38 no.12
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• pp.67-78
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• 2022

In this study, the measurement results of the coastal deep soft ground buried in the upper part of the dredged clay were analyzed and compared with the current specification standards. Based on the results, a suitable proposal was suggested for the selection, installation, data arrangement, and analysis of each instrument used in the deep soft ground improvement construction. The pore water pressure meter has a range of 1.5 times or more of the expected measurement range, considering the field conditions of the soft ground. The groundwater level meter installed in the horizontal drainage layer checks the change in the groundwater level during the embanking as well as the performance of the catchment well and the horizontal drainage layer. Therefore, it is important to manage so that the groundwater level exists inside the horizontal drainage layer during embanking. It is enough to install the inclinometer in the gravel layer below the soft ground or weathered rock with an N value of 40 or more for the deep soft ground. It seems desirable to install a screw type for differential settlement meter. However, the screw type should not settle due to its own weight. Considering that it is a dredged landfill where subsidence occurs significantly, it is sufficient to manage the tolerance of leveling at about 10 mm (L is the one-way distance (km)).