• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.3A
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• pp.235-241
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• 2009

PSC girder bridge is known to be more economical than other types of bridges and has been usually applied to a span range of 25 m to 35 m according to the standard shapes for highway bridges in Korea. The spans of the recently developed new types of PSC girders are also limited to 50 m at most. In this study, therefore, feasibility of the long-span PSC girder that reaches more than 50 m is investigated by applying several strategies from the perspectives of materials, design and construction. A systematic procedure is proposed that can be used to assess the effect of each strategy on the span. The proposed scheme adopts a graphical approach that represents a relationship between the number of prestressing tendons and the span, and is derived on a basis of safety assessment equations of the girder in each stage of fabrication and in service. In the companion paper, the amount of span extension is quantitatively evaluated by applying the proposed scheme into a sample PSC girder bridge.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4D
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• pp.555-561
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• 2009

In lieu of section profile data, a fitting of the bored tunnel shape is more significant confirmation for maintenance of a tunnel. Before the permit on the completion of a tunnel, deformation of the completed tunnel with respect to the design model are considered. And deformation can be produced at continuously along the entire of the tunnel section. This study firstly includes an analysis of algebraic approach and test it with an observed field data. And then a number of methods, line search method, genetic algorithm, and pattern search methods, are compared with the 3D tunnel shape fitting. Algebraic methods can solve a simple circular cylinder type as like a railway tunnel. However, a more complex model (compound circular curve and non circular) as like a highway tunnel has to be solved with soft computing tools in the cause of conditional constraints. The genetic algorithm and pattern search methods are computationally more intensive, but they are more flexible at a complex condition. The line search method is fastest, but it needs a narrow bounds of the initial values.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.220-220
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• 2022

물관리 일원화, 물관리기본법 제정·시행 등 우리나라 물관리 체계의 혁신기에 정책의 구심점 역할을 수행할 통합 물관리 전략 마련이 요구됨에 따라, 최근 관계부처 합동으로 「제1차 국가물관기본계획(2021~2030)」을 수립하여 공표·발간되었다. 국가물관리기본계획에서는 유역단위의 물관리를 원칙(12대 기본원칙 중(中))로 하며, 물관리 3대분야(수질·수생태, 이수, 치수)에 대한 추진전략을 수립하였다. 또한, 지속가능한 물관리 체계를 구축하기 위해 추진전략별 주요 관리지표를 설정하였으며, 이를 통해 물관리 방향을 정립하고 분야별 관련 및 하위계획과의 일관성·정합성을 유지하고자 하였다. 이에 본 연구에서는 추진전략별 주요 관리지표 중, 유역 재해안전도와 관련하여 하천범람에 대한 기존의 치수안전도의 한계점을 검토하고 유역단위의 치수관리 현황을 평가 할 수 있는 방안을 마련하고자 하였다. 과거 유역종합치수계획에서의 치수안전도는 홍수피해잠재능(PFD)을 적용하여 등급별 홍수방어대책 수립방향 및 하천의 설계빈도 조정을 검토하였으며, 홍수피해잠재능(PFD)의 실무적 적용 어려움(산정인자 다(多)), 설계빈도와의 연계성 부족, 치수단위구역의 공간적 정확성 미흡 등에 대한 개선·보완의 의견이 제기되어 왔다. 또한, 유역내 전체하천이 아닌 주요 하천을 대상으로만 치수안전도 설정하여 유역단위의 치수관리에 한계가 있으며, 하천 전체구간의 설계빈도 상향에 따른 홍수방어대책이 비경제적인 것으로 판단된다. 따라서, 기존의 치수안전도의 한계점을 개선하기 위하여 홍수피해잠재능(PFD)의 산정인자 단순화, 홍수위험지도를 활용을 통한 치수단위구역의 공간적 정확도 향상 및 치수단위구역별 설계빈도 조정 가능 등의 개선방안을 검토하였으며, 빈도별 치수단위구역의 홍수피해잠재능(PFD)의 통계적 특성 분석을 통해 등급 설정 및 설계빈도 조정 기준을 제시하였다. 그리고 유역내 전체하천에 대한 치수단위구역별 치수안전도를 설정하고, 중권역 단위의 치수안전도를 평가하여 유역단위의 치수관리 현황을 정량적으로 제시함에 유역 재해안전도로 활용이 가능할 것으로 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.371-371
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• 2022

하천관리지리정보시스템(RIMGIS)은 하천정보의 표준화 및 전산화를 통한 정보제공과 하천에 관련한 업무를 지원하기 위해 개발된 시스템으로 5개의 지방국토관리청에서 관리하고 있는 하천대장 및 부도, 구조물도 등의 다양한 하천 관련 정보를 정보화하여 인허가 및 하천기본계획 등의 하천업무를 신속하고 효율적으로 수행할 수 있도록 운영되고 있다. 국가 주요 기반시설을 생애주기 관점에서 관리하고 소요재원의 확보근거를 마련하고자 "지속 가능한 기반시설 관리 기본법"이 제정되었고 최근에 시행되었다. 이에 따라 국토안전관리원에서는 도로·철도·철도 하천 등과 같은 사회기반시설(15종)의 노후화에 대비하여 전략적인 투자와 관리방식 도입을 목적으로 인프라 총조사 사업을 진하천 등과 같은 사회기반시설(15종)의 노후화에 대비하여 전략적인 투자와 관리방식 도입을 목적으로 인프라 총조사 사업을 진행하고 관리를 위해서 기반터 시스템을 도입하였다. 하천관리지리정보시스템과 기반터 시스템은 하천 기반시설의 정보가 데이터베이스에서 다뤄진다는 점에서 유사하지만, 기반터 시스템은 하천관리지리정보시스템과 달리 유지관리 측면에 대한 필요한 보수 주기, 필요 예산 등과 같은 정보를 산정할 수 있도록 프레임워크가 구성되어 있다. 그러나 하천과 기반시설의 코드를 연결하는 작업들은 현재 상황에서는 미흡한 실정이고, 유지관리와 시설물의 노후화를 가속화하는 홍수와 침수피해 등을 전체적으로 고려할 수 있는 방안에 대한 연구도 미진한 상황이다. 이에 본 연구에서는 하천 기반시설의 유지관리를 위해 하천, 제방, 인명에 대한 위험지수를 고려한 잠재 인명피해 위험도와 잠재 홍수피해 위험도를 평가기준으로 설정하고 적용하였다. 또한 이를 포함시킨 투자우선순위 평가기법을 도입하여 감가상각과 위험요소 등을 고려할 수 있는 데이터베이스 구성 방안을 제시하고자 한다.

• The korean journal of orthodontics
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• v.30 no.2 s.79
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• pp.127-142
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• 2000

This study have been carried out to find out the mechnical effect of Multiloop Edgewise Arch Wire(MEAW) making use of the finite element method. The tip back bend of MEAW taken in this analysis is $5^{\circ},\;10{\circ}\;and\;15{\circ}$. In addition, Class II or up & down elastic is applied to find out stress distribution and their values in PDL. A adult male of normal occlusion was selected to create the models of teeth and PDL. And the model of MEAW was also created using commercial finite element code (ANSYS version 5.2). The MEAW is forcibly engaged with a class II or up & down elastic, to determine the initial stress generated in PDL. Comparing the compressive and tensile stress at each reference-planes, following results are obtained. 1. When a MEAW of $5^{\circ},\;10{\circ}\;15{\circ}$ tip back bend was engaged with Class II or up & down elastic, the distribution of compressive, tensile stress in entire PDL is similar in each case. 2. The values of compressive and tensile stress in PDL is higher in $15{\circ}$ tip back bend case than in $10{\circ}\;or\;15{\circ}$ tip back bend case. 3. In the distal PDL of 1st and 2nd molar, compressive stress appears. The compressive area is more wide and its values is higher in PDL of 2nd molar than those in 1st molar. The compressive area and its values become more wide and higher according to the increase of the tip back bend. 4. The values of compressive stress are comparatively smaIIer in PDL of molars than those in premolars. 5. Comparing class II and up & down elastic case, tensile stress values in anterior teeth PDL are smaller md their distribution is more wide in up & down elastic case than class If elastic case. On another hand, there is no difference in distribution and stress values in PDL of posterior teeth between two cases. 6. Comparing the tensile area in PDL of anterior teeth, tensile stress values are maximum in PDL of canine.

• The korean journal of orthodontics
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• v.34 no.4 s.105
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• pp.303-312
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• 2004

An unfavorable tipping movement can occur during the retraction of anterior teeth because orthodontic force is loaded by brackets positioned far from the center of resistance. To avoid this unfavorable movement, a compensating curved wire or lingual root torque wire is used. The purpose of this study is to investigate, using photoelastic material, the distribution of initial stress associated with the retraction of the incisors according to the degree of the compensating curve, to model changes associated with tooth ud alveolar bone structure. The following results were obtained by analysis of the polarizing plate of the effects of initial stress resulting from retraction of the anterior teeth: 1. When the incisors were retracted using combination archwire or sliding mechanics, the maximal polarizing pattern of the apical area decreased as the degree of the compensating owe increased from 0 to 15 to 30. 2. When the incisors were retracted by the combination archwire or sliding mechanics, the maximal polarizing pattern of the canine and premolar area increased as the degree of the compensating curve increased from 0to 15to 30. 3. A lower degree of polarizing patterns were associated with the combination archwire technique than the sliding mechanics technique at a given force. The above results indicate that there is no significant difference between the combination loop archwire technique and sliding mechanics, for the retraction of maxillary anterior teeth with decreased lingual tipping tendency by a compensating curve on the arch wire. However, the use of sliding mechanics is more effective for the prevention of lingual inclination of the anterior teeth, because the hook used in sliding mechanics is closer to the center of resistance of the maxillary anterior teeth.

• Land and Housing Review
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• v.8 no.4
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• pp.233-247
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• 2017

In Europe and the USA, the use of limit state design method has been established, and the Korea Ministry of Land, Transport and Maritime Affairs has implemented the bridge substructure design standard based on the critical state. But Korean piling methods and ground conditions are different from Europe and USA, the limit state design method can not be used immediately. In this study, the resistance coefficient was proposed by comparing and analyzing the results of the static load test(9 times) and dynamic load tests(9 times of EOID and 9 times of Restrike) with the bearing capacity calculated by Meyerhof(LH design standard, Road bridge design standard) method and surcharge load method(using Terzaghi's bearing capacity coefficient and Hansen & Vesic's bearing capacity coefficient). The previous LHI study showed the resistance coefficient of the LH design standard was 0.36 ~ 0.44, and this research result showed the resistance coefficient was 0.39 ~ 0.48 which is about 8% higher than the previous study. In this study, we tried to obtain the resistance coefficient mainly from the static load test and the resistance coefficient was 0.57 ~ 0.69(Meyhof method : LH design standard) based on the ultimate bearing capacity and the resistance coefficient was 0.49 ~ 0.60(Meyhof method : LH design standard) based on the Davissons bearing capacity. The difference of the resistance coefficient between the static and dynamic load test was greater than that we expected, we proposed the resistance coefficient(0.52 ~ 0.62 : Meyerhof method: LH design standard) using the modified bearing capacity of the dynamic load test. Summarizing the result, the coefficient of resistance obtained from the static and dynamic load tests was 0.35 ~ 0.76, which is greater than 0.3 suggested by the Road bridge design standard, so the economical design might be possible using the coefficient of resistance proposed by this study.

• Land and Housing Review
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• v.9 no.3
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• pp.1-8
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• 2018

In Europe and the United States, the use of limit states design has almost been established for pile foundation design. According to the global trend, the Ministry of Land, Transport and Maritime Affairs has established the basic design criteria of the bridge under the limit state design method. However, it is difficult to reflect on the design right now because of lack of research on resistance coefficient of the pile method and ground condition. In this study, to obtain the resistance coefficient of PHC bored pile which is widely used in Korea, the bearing capacity calculated by the LH design standard and the bridge design standard method, the static load test(21 times) and the dynamic load test(EOID 21 times, Restrike 21) The reliability analysis was performed on the results. The analysis of the resistance coefficient of PHC bored pile by loading test was analyzed by adding more than two times data. As a result, the resistance coefficient obtained from the static load test(ultimate bearing capacity) was 0.64 ~ 0.83 according to the design formula and the target reliability index, and the resistance coefficient obtained from the dynamic load test(ultimate bearing capacity) was 0.42~0.55. Respectively. The resistance coefficient obtained from the modified bearing capacity of dynamic load test(EOID's ultimate end bearing capacity + restrike's ultimate skin bearing capacity) was 0.55~0.71, which was reduced to about 14% when compared with the resistance coefficient obtained by the static load test(ultimate bearing capacity). As a result of the addition of the data, the resistivity coefficient was not changed significantly, even if the data were increased more than 2 times by the same value or 0.04 as the previous resistance coefficient. In conclusion, the overall resistance coefficient calculated by the static load test and dynamic load tests in this study is larger than the resistance coefficient of 0.3 suggested by the bridge design standard(2015).

• Journal of the Korean Institute of Landscape Architecture
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• v.51 no.1
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• pp.72-84
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• 2023

The Rural Revitalization Strategy (2018-2022), published by the Chinese State Council in 2018, represents a new period of rural development in China. Suburban areas are more convenient than other rural areas in integrated urban-rural development but are under greater pressure from construction and industrial pollution. As a rural area with a high proportion of rural areas, it would be valuable for Henan province to gain a comprehensive grasp of rural human settlementst while identifying problems and proposing solutions. The purpose of this study is to analyze the satisfaction of the evaluation items based on the usage status and life perception of the residents of Tai Nan village, a suburb-type rural village in Henan province. The study proposes improvement programs based on the evaluation results. As a result of the study, 24 evaluation items were derived and divided into five categories: "Living Service Facilities", "Housing Environment, "Road Environment", "Health & Ecology Environment", and "Social & Cultural Environment". The Fuzzy Comprehensive Evaluation Method was used to find the overall satisfaction level of the human living environment in Tai Nan village, which was "average", among which "Living Service Facilities" was the most important "Health & Ecology Environment" was the least satisfied. Based on these results, an improvement plan is proposed in three stages. First, the living service will be improved while strengthening the facility management of the hygiene and the ecological environment. Second, reasonable improvement of housing and the road environment will be applied. Third, programs will be introduced to cultivate residents' ability to build their own and improve the social and cultural environment. This study provides basic data for the future improvement of rural settlements in the suburban areas of Henan province and is of great significance in gradually improving the the residents' quality of life.

• Tunnel and Underground Space
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• v.19 no.6
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• pp.498-506
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• 2009

The stability assessment of a concrete liner of a compressed air storage tunnel should be performed by an approach which is different from that commonly used for the liners of road tunnels, since the liner is exposed to high air pressure. In this study, the stability analysis method for the liner of compressed air storage tunnel is proposed based on the elastic and elasto-plastic solutions of the thick-walled cylinder problem. In case of elastic analysis, the yield initiation condition at the inner boundary is considered as the failure condition of the liner, while the condition which results in the extension of yielding zone to a certain depth is taken as a failure indicator of the liner in the elasto-plastic analysis taking Mohr-Coulomb criterion. The application of the proposed method revealed that the influence of the relative magnitude of boundary loads on the stability of liner is considerable. In particular, noting that the estimation of the outer boundary load may be relatively difficult, it is thought that the precise prediction of outer boundary load is very important in the analysis. Accordingly, the emphasis is put on the selection of the liner installation time, which may govern the magnitude of outer boundary load.