• Journal of the Korean association of regional geographers
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• v.22 no.2
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• pp.369-382
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• 2016

The studies on the rural housing have focused on folk housing, but this study focuses on the contemporary rural housing with special reference to the roof types/materials and the outer wall materials. The research area of this study is the fourteen rural settlements in Jeju Island. The hip roof type, the hip/flat roof type, the simple-flat roof type, the gable roof type, and the eyebrow-and-flat roof type are the most frequent roof types. Among the roof materials, the precoated steel plate, the artificial slate, the cement, the cement/roof tile, and the cement/artificial slate are the most frequent materials. The cement holds more than a half of the outer wall materials, and the cement/basalt rock, the tile/cement, the tile, and the diverse siding are the next frequent outer wall materials. The comparison of the rural housing reveals that there are some clear differences between Jeju Island and Gyeongnam Province in terms of the roof types and the outer wall materials.

• Journal of Navigation and Port Research
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• v.27 no.4
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• pp.479-484
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• 2003

In the case of the feeder bus route choice, it is more desirable to choose the route by treating as a single route linked from origin to destination than the whole network. This study is to establish a concept that frames the feeder bus route choice technique for the change of the existing single bus route or the creation of the new feeder bus route. The concept of the feeder bus route choice technique in this study is not to frame the whole bus network but to frame a single route to a unit O-D pair. So, this study has the assumption that does not consider the waiting and transfer time at the bus stop. This system technique consists of the following phases: I) limitation of the road network examined for the study, ii) enumeration of the appropriate candidate routes by the permissive route length, and iii) determination of the optimum bus route by the route evaluation value.

• Journal of Korean Society of Steel Construction
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• v.23 no.2
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• pp.147-158
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• 2011

The purpose of this research was to analyze the connections of the seismic-performance values for domestic-performance-based designs. Basic research on the performance design method has been increasing of late, along with performance-based organization investigations. These investigations concern the performance level state of steel structure buildings. According to the performance limit state, seismic-performance values should be presented as appropriate steel structure engineering amounts. The first step, based on the full-scale steel structure experiments, involves researching on the making of a basic document. The moment-rotation angle relationship results of the experiment on the moment-frame connection were used to assort the functional and undamaged limits, which were assumed to be less than the yield moment. Moreover, the repairable and safety limits, which were assumed to exist between the yield and maximum moments, were assorted by investigating the accumulated plastic deformation ratio.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.12
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• pp.1503-1512
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• 2013

In this study, we proposed an indentation evaluation method for fracture toughness using cohesive finite element simulations. First, we examined the effect of material properties (yield strain, Poisson's ratio, and elastic modulus) on crack size during Vickers indentation and then generated a regression formula that explains the relations among fracture toughness, indentation load, and crack size. We also proposed another indentation formula for fracture toughness evaluation using the contact size a and E/H (H: hardness). Finally, we examined the relation between the crack size and the indenter shapes. Based on this, we can generate from the formula obtained using the Vickers indenter a formula for an indenter of different shapes. Using the proposed method, fracture toughness is directly estimated from indentation data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.5
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• pp.421-428
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• 2004

This study concerns the characteristics of boiling heat transfer in two-phase closed thermosyphons with various micro grooves. A study was carried out with the performance of the heat transfer of the thermosyphon having 60 internal micro grooves in which boiling and condensation occur. A plain thermosyphon having the same inner and outer diameter as the grooved thermosyphon is also tested for comparison. Distilled water, methanol, ethanol have been used as the working fluid. The heat flux and the boiling heat transfer coefficient at the evaporator zone are estimated from the experimental results. The experimental results have been assessed and compared with existing correlations. Imura's and Kusuda's correlation for boiling showed in good agreement with experimental results within ${\pm}20{\%}$ in plain thermosyphon.

• Journal of agriculture & life science
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• v.44 no.3
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• pp.89-97
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• 2010

In the contingent valuation method (CVM) survey, we employed double-bounded discrete choice (DBDC) question to investigate the willingness to pay (WTP). The estimation results for the bivariate logit model show that respondents are willing to pay 329,256 won per year. The model with covariate variables suggests that the covariate effects help describe behavioral or preference tendencies. Double-bounded models increase efficiency over single dichotomous choice models, because the answers yes-no or no-yes yield clear bounds on WTP.

• Journal of Korea Water Resources Association
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• v.52 no.spc2
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• pp.791-799
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• 2019

This study explained the historical changes in the habitat structures based on the aerial photographs (1948, 1967, 1973, 1989 and 2010) of the mid-stream reach of the Mangyeong River. The habitat structure was divided into landforms and aquatic habitats. The landform was classified into bare land, vegetated land, water surface, farmland and artificial land. The aquatic habitat was classified into natural riffle, artificial riffle, run, head wando, tail wando, mid wando, pond and chute channel. The ratio of bareland decreased, and water surface and vegetated land increased after the excavation in 1970s and since the construction of weir in 1980s. As historical changes of aquatic habitat, ratio of run decreased sharply while mid wando increased sharply. aquatic habitats such as head wando, tail wando, and pond located on bars decreased dramatically.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.459-459
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• 2018

서낙동강은 당초 낙동강 본류였으나 1934년 김해평야 일원의 농업용수 공급을 위하여 건설된 대저수문과 녹산수문의 완공 이후 현재의 상태로 유지되고 있다. 서낙동강은 대저수문을 통한 유입과 녹산수문, 녹산배수펌프장을 통한 방류가 시행되고 있으며, 이러한 운영은 외해 조위조건에 따라 간헐적으로 운영되고 있어서, 수체의 정체로 인한 오염도가 높은 실정이다. 또한, 서낙동강 유역은 에코델타시티 등 다양한 개발계획이 수립됨에 따라 수질관리를 위한 여건도 변화할 것으로 예상되며, 이러한 개발에 따른 다양한 수질개선에 대한 사회적 요구가 증대됨에 따라 이를 위한 물순환 개선과 유역에서의 오염부하 저감 등 다양한 수질개선 대책이 필요하다. 본 연구에서는 그간 서낙동강을 대상으로 시행되었던 연구결과와 현재 시행중인 물순환에 대한 효과를 검토하고, 이를 정량화하기 위한 2차원 수리 수질모형(CE-QUAL-W2)을 구축 활용하여 현행 물순환 방안의 운영 효과를 분석하고자 하였다. 당초 환경영향평가시 제시되었던 대저수문과 맥도수문을 통한 유입과 맥도배수펌프장을 통한 유출로 서낙동강, 평강천, 맥도강의 수질을 개선하고자 했던 물순환 계획은 여러 가지 여건으로 인해 시행되지 못하고 있으며, 현재는 매주 강서구청에서 맥도배수펌프장을 이용하여 평강천과 맥도강의 수위를 저하시킨 이후 서낙동강의 하천수를 유입시키는 형태로 물순환을 시행하고 있다. 이러한 현행 물순환 방안에 대한 분석을 위하여 서낙동강, 평강천, 맥도강 구간에 대하여 2차원 수리 수질모형(CE-QUAL-W2)을 이용하여 모의한 결과 현재의 물순환 방법으로는 물순환 유량이 증가하더라도 수질개선에 한계가 있는 것으로 나타났다. 이는 서낙동강에 낙동강 하천수가 대저수문을 통하여 유입된 이후 장기간 체류함에 따라 유역에서의 오염물질 유입의 영향이 크게 나타나며, 이에 따라 평강천과 맥도강에 유입되는 경우 수질개선이 제한적인 것으로 판단된다. 추가적으로 현재 서낙동강 대비 상대적으로 수질이 양호한 낙동강 본류의 하천수를 신규 수문 등의 시설물을 통하여 유입시키는 조건에 대한 분석 결과 현행 물순환 대비 효과가 크며 당초 예상했던 환경영향평가시 목표수질을 달성할 수 있을 것으로 판단보다 상세한 분석과 검토가 필요할 것으로 판단된다.

• Journal of the Korean Society for Library and Information Science
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• v.55 no.4
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• pp.267-291
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• 2021

Due to the global pandemic caused by COVID-19 in 2020, there have been major changes in the education sites. Universities have fully introduced remote learning, which was considered as an auxiliary education, and non-face-to-face classes have become commonplace, and professors and students are making great efforts to adapt to the new educational environment. In order to improve the quality of non-face-to-face lectures amid these changes, it is necessary to study the factors affecting lecture satisfaction. Therefore, This paper presents a new methodology using big data to identify the factors affecting university lecture satisfaction changed before and after COVID-19. We use Topic Modeling method to analyze lecture reviews before and after COVID-19, and identify factors affecting lecture satisfaction. Through this, we suggest the direction for university education to move forward. In addition, we can identify the factors of satisfaction and dissatisfaction of lectures from multiangle by establishing a topic classification model with an F1-score of 0.84 based on KoBERT, a deep learning language model, and further contribute to continuous qualitative improvement of lecture satisfaction.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.1
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• pp.1-8
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• 2019

This research mainly focuses on examining the applicability of the deterministic model SLOSH (Sea, Lake and Overland Surges from Hurricanes) on Seas covering South Korea. Also, a simple bathtub approach which estimates coastal inundation area is validated as a first step of estimating effects of sea-level rise on the coastal cities of South Korea according to climate change. Firstly, the typhoon-induced surges are obtained from the model SLOSH by adopting historical typhoons MAEMI (0314) and BOLAVEN (1215). The results are compared to observational, typhoon-induced surge heights at several tidal stations. The coastal inundation area is estimated by comparing the maximum envelop of waves (MEOW) and the elevation of coastal land. It reproduces well the inundation area. It can be seen that this research gained applicability for estimating further potential coastal inundation with climate changes.