• Journal of the Korean Geographical Society
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• v.40 no.6 s.111
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• pp.770-788
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• 2005

In this article, major research trends are examined mainly from articles published in Journal of the Korean Geography, academic society journals of sub-fields in geography and Ph.D. dissertations in geography of universities in Korea. Based on the research trends up to current point, issues and research directions in order to raise the status of Korean Geography in the twenty first century are prospected. Sixty years of Korean Geography can be divided into 4 periods such as before 1970s, during the 1980s, during the 1990s, and the period after the 2001. Each period of time revealed distinct aspects of development both quantitatively and qualitatively. For the last 60 years, the study of Korean Geography has gone through enormous changes in the number of articles with dynamics and variety in contents and methodology, breathing with the changes of the Korean society. Experiencing urbanization and industrialization along with rapid economical growth, the study of Korean Geography has progressed by analyzing the issues and problems of national space and conducting various researches from the case studies for problem-solving to the theoretical and policy oriented studies. The key-words such as 'knowledge based information society', 'aged society', and 'the era of globalization' will be realized in the twenty flit century. And environment-friendly policies for sustainable development will be more stressed in a globalized world. In order to provide research methods and alternatives suitable for newly transformed global society and for utilizing the essence of Geography in the future, the studies on Korean Geography should actively focus on integrative studies between physical and human geography, on interdisciplinary studies, on regional studies related to foreign countries and North Korea, and on the establishment of Korean geographical theory and model.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.5
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• pp.1199-1207
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• 2015

One-person household is increasing by the growth of unemployment, divorce, aging in Korea. In particular, One-person households have rapidly increased around Farming & Fishing Regions. In this regard, this research aims to suggest the directions of housing supply for one-person households suitable for Farming & Fishing Regions by investigating the characteristics of one-person households in the social, economic, and physical aspects. This study found out that one-person households could be divided into two groups; one group lived in industrialized Farming & Fishing Regions and the other group lived in traditional Farming & Fishing Regions. For one-person households living in industrialized Farming & Fishing Regions, it is necessary to provide age-mixed residential sites where companies and manufacturers are condensed. On the other hand, for the one-person households living in traditional Farming & Fishing Regions, it in necessary to provide multi-person housing units for increasing the quality of life ofne-person households.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.5
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• pp.1039-1049
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• 2015

The inflow estimation at large multipurpose dam reservoir is carried out by considering the water balance among the discharge, the storage change during unit time interval obtained from the observed water level near dam structure and area-volume curve. This method can be ideal for level pool reservoir but include potential errors when the inflow is influenced by the water level slope due to backwater effects from upstream flood inflows and strong wind induced by typhoon. In addition, the other uncertainties arisen from the storage reduction due to sedimentation after the dam construction and water level noise due to mechanical vibration transmitted from the electric power generator. These uncertainties impedes the accurate hydraulic inflow measurement requiring exquisite hydrometric data arrangement for reservoir waterbody. In this study, the distributed hydrologic model using UBC-3P boundary setting was applied and its feasibility was evaluated. Finally, the modeling performance has been verified since the calculated determination coefficient has been in between 0.96 to 0.99 after comparing with observed peak inflow and total inflow at Namgang dam reservoir.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5B
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• pp.449-457
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• 2011

Recently, increasing heavy rainfalls due to climate change and/or variability result in hydro-climatic disasters being accelerated. To cope with the extreme rainfall events in the future, hydrologic frequency analysis is usually used to estimate design rainfalls in a design target year. The rainfall data series applied to the hydrologic frequency analysis is assumed to be stationary. However, recent observations indicate that the data series might not preserve the statistical properties of rainfall in the future. This study incorporated the residual analysis and the hydrologic frequency analysis to estimate design rainfalls in a design target year considering the non-stationarity of rainfall. The residual time series were generated using a linear regression line constructed from the observations. After finding the proper probability density function for the residuals, considering the increasing or decreasing trend, rainfalls quantiles were estimated corresponding to specific design return periods in a design target year. The results from applying the method to 14 gauging stations indicate that the proposed method provides appropriate design rainfalls and reduces the prediction errors compared with the conventional rainfall frequency analysis which assumes that the rainfall data are stationary.

• Composites Research
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• v.26 no.1
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• pp.14-20
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• 2013

The electrospun PVDF containing CNT was made for fabricating materials of the actuator. The electrochemical and their actuating movement were evaluated for the actuator performance in the electrochemical environment. The actuator (which was fabricated by electrospinning) had some advantages, i.e., good dispersion and flexible properties. In the electrospinning process, the final product would have different forms based on different essential factors. In this work, electrospun nanofibers were aligned by using the drum-type collector, and the morphology was identified via the field emission-scanning electron microscope (FE-SEM). The uniform dispersion of CNT in PVDF nanofiber was observed by electron probe X-ray micro-analysis (EPMA) test. The results of tensile strength and electrical resistivity provided the aligned state. The electrospun CNT/PVDF nanofiber sheet on the aligned direction showed better mechanical and electrical properties than the case of the vertically-aligned direction. The efficiency and electrical capacities of electrospun CNT/PVDF nanofiber sheets were compared with the cast PVDF sheet for actuator application. Electrospun CNT/PVDF nanofiber sheet exhibited much better the case of actuator performance than cast neat PVDF actuator, due to the excellent electrical connecting areas.

• Journal of the Korean School Mathematics Society
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• v.17 no.4
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• pp.679-695
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• 2014

In this paper we survey the career awareness, demand, and preparation of the students of the department of mathematics education and provide basic data for establishment of career diversification strategies. For this we examined the followings: (1) department selected time and motivation, (2) satisfaction with the selection and training courses, (3) hope and change for a career after graduation, (4) related jobs and career awareness. As a result, most of the students over the course of the high school and middle school chose a career in mathematics education, the biggest motivation appeared to be due to selection was deemed suitable for individual aptitudes. Due to this reason he/she is satisfied with the selection and training process and the curriculum of mathematics education appeared to think it would be helpful to his/her career. It can be observed that the number of students increased to think of another job, depending on the grade ascent. Mostly due to the difficulty of major study as grade up, high competition and low success rate of teacher employment test, employment reduction in the number of teachers.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.8
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• pp.857-862
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• 2014

The research on a thermal stress control layer (TSCL) begins to undertake to reduce residual stress and strain in the vicinity of the joined region between the hardfacing layer and the base part. The goal of this paper is to estimate the material combination and the thickness of TSCL for the Stellite21 hardfaced STD61 hot working tool steel via three-dimensional finite element analysis (FEA). TSCL is created by the combination of Stellite21 and STD61. The thickness of TSCL ranges from 0.5 mm to 1.5 mm. The influence of the material combination and the thickness of TSCL on temperature, thermal stress and thermal strain distributions of the hardfaced part have been investigated. The results of the investigation have been revealed that a proper material combination of TSCL is Stellite21 of 50 % and STD61 of 50 %, and its appropriate thickness is 1.0 mm.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.5
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• pp.485-501
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• 2012

This study aims to experimentally investigate ground settlement and ground movement around the square pipe by its penetration in sandy ground. A series of laboratory model tests were carried out with a small-scale auger equipment for penetration of a square pipe as well as a newly designed test box with a sand raining equipment. From the experiments, it is shown that a square pipe induces ground movement evenly around it in a low overburden condition. However, as the overburden becomes higher, ground movement by a square pipe is concentrated mainly above it. Especially, horizontal strain above the square pipe was mainly dominated by its penetration. In addition, sand surface movement is the smallest in case of the dimensionless penetration rate equal to 0.2. When its penetration rate of the square pipe is fixed, the rotation speed of auger controls surface movement whether it is settlement or heaving. Therefore, the selection of an optimal dimensionless rate for the square pipe is a key design factor to minimize ground settlement in a trenchless construction.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.6
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• pp.623-641
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• 2020

About 5 km length of tunnels were constructed by mechanized tunnelling method using closed type shield TBM. In order to avoid construction delay problems for ensuring timely electricity transmission, it is necessary to increase the prediction accuracy of the excavation process involving machines according to rock mass types. This is important to corroborate the project duration and optimum operation for various considerations involved in the machine. So, full-scale tunnelling tests were performed for developing the advance rate model to be appropriately used for 3.6 m diameter shield TBM. About 100 test cases were established and performed using various operational parameters such as thrust force and rotational speed of cuttterhead in representative uniaxial compressive strengths. Accordingly, relationships between normal force and penetration depth and, between UCS and torque were suggested which consider UCS and thrust force conditions according to weathered, soft, hard rocks. Capacity analysis of cutterhead was performed and optimum operational conditions were also suggested based on the developed model. Based on this study, it can be expected that the project construction duration can be reduced and users can benefit from the provision of earlier service.

• Journal of Korean Society for Geospatial Information Science
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• v.21 no.2
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• pp.63-69
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• 2013

Change detection technique is essential to various applications of Very High-Resolution(VHR) satellite imagery and land monitoring. However, change detection accuracy of VHR satellite imagery can be decreased due to various geometrical dissimilarity. In this paper, the existing fusion evaluation indexes were revised and applied to improve VHR imagery based change detection accuracy between multi-temporal images. In addition, appropriate change detection methodology of VHR images are proposed through comparison of general change detection algorithm with cross-sharpened image based change detection algorithm. For these purpose, ERGAS, UIQI and SAM, which were representative fusion evaluation index, were applied to unsupervised change detection, and then, these were compared with CVA based change detection result. Methodologies for minimizing the geometrical error of change detection algorithm are analyzed through evaluation of change detection accuracy corresponding to image fusion method, also. The experimental results are shown that change detection accuracy based on ERGAS index by using cross-sharpened images is higher than these based on other estimation index by using general fused image.