• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.368-368
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• 2017

근대적 기상관측이 시작된 1905년 이후 우리나라의 연평균 강수량은 증가하고 있으나 강수량 변동폭 또한 커지면서 최갈수 기간의 영향을 받는 댐 등 대규모 수공구조물의 용수공급능력은 감소되고 있다. 또한 지역별 강수량과 인구 편차로 공간적으로 이용 가능한 수자원의 불균형이 발생하고 있어 지역적인 물 공급의 안정성과 형평성은 여전히 취약한 상황이다. 하지만 사회적 공감대 형성이 쉽지 않은 대규모 수자원개발 추진은 어려운 여건이며 국민들의 안전하고 맑은 물에 대한 수요 또한 지속적으로 증대되고 있어 이를 해소하기 위한 다각적인 대책 마련이 필요한 상황이다. 본 연구에서는 기 확보된 수자원의 효율적이고 공평한 활용을 위해 국내 용수공급의 중추적인 역할을 담당하고 있는 댐을 대상으로 댐간 연결을 통한 용수공급 방안을 제시하였다. 이를 위하여 소양강댐, 충주댐 등 다목적댐 16개 및 광동댐, 영천댐 등 용수댐 12개 총 28개댐의 용수공급능력 평가와 장래 용수수요량 조사를 실시하였으며 장래 용수부족 지역 해소를 위한 상시공급과 극한가뭄 등 재난 대처를 위한 비상시공급 방안을 검토하였다. 상시공급은 댐 용수공급능력 평가를 통하여 기본계획공급량 대비 여유수량을 갖는 댐에서 장래 용수수요 증가, 용수공급능력 감소 등으로 공급 용수가 부족한 인근 댐으로 공급하는 방식이며 용수 공급량은 저수지 모의운영을 통하여 양댐의 이수안전도(분석 기간중 1회에 한하여 물 부족 허용)를 충족시키는 수량을 산정하였다. 비상시공급은 타수계 및 근거리간 연결, 가뭄 예상지역을 기준으로 대상 댐을 검토하였으며 용수 공급량은 공급댐의 유지용수와 관개용수를 이용하여 공급받는 댐의 생 공용수 20% 공급가능시 공급량으로 산정하였다. 검토 결과 상시공급은 소양강댐에서 횡성댐으로 86천$m^3$/일, 장흥댐에서 주암본댐으로 127천$m^3$/일, 남강댐에서 수어댐으로 $140m^3$/일, 비상시 공급은 충주댐과 대청댐, 충주댐과 안동댐간 각각 500천$m^3$/일 공급을 통하여 장래 용수부족 지역의 물 부족 해소와 극한가뭄 등 비상상황의 대처가 가능한 것으로 분석되었다. 본 연구는 기후변화와 사회가치적으로 변화하고 있는 수자원 환경에 능동적으로 대처하기 위한 대책의 일환으로 고안된 것이며, 향후 유역간 물 이동에 따른 현행 수리권제도 및 어류, 수질변화에 따른 환경영향 등에 대하여 추가적인 연구가 필요할 것으로 판단된다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1A
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• pp.71-80
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• 2010

Bridge deck is directly influenced by environment and vehicle load, it is easily damaged so that it requires an appropriate repair and retrofit. Therefore, developing a bridge deck with high durability is necessary in order to minimize the maintenance of bridge deck and use it to its design life. In this study, static test was carried out to evaluate a fatigue capacity of steel-concrete composite deck, which was newly developed by supplementing problems of existing reinforced concrete deck. Based on results from the static test, fatigue load was decided, and fatigue test was conducted under the constant amplitude repeated load. From the fatigue tests, the S-N curve regarding principle structural details of composite deck was made, and characteristics of fatigue behavior was estimated by comparing and evaluating it with fatigue design criteria. In addition, fatigue design guideline was presented. As a result, it is found that each structural details of composite deck proposed by this study, such as upper flange of corrugated steel plate and middle section of it, shear connector and lower flange of corrugated steel plate, is satisfying the fatigue strength.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.4
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• pp.479-499
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• 2019

State assessment of an operational tunnel is usually done by performing visual inspection and durability tests by following the detailed guideline for safety inspection (SI) and/ or precision inspection for safety and diagnosis (PISD). In this study, 12 NATM tunnels, which have been operational for more than 10 years, were inspected to figure out the cause of longitudinal cracks for the purpose of modifying the scoring items in the state assessment NATM tunnel related to the longitudinal crack and the thickness of concrete lining. All investigated tunnels were classified into four groups depending on the shape and usage of each tunnel. The causes of longitudinal crack occurrence were analyzed by investigating the correlations between the longitudinal crack and the following four factors: the patterns of ground excavation; construction state of primary support system; characteristics of material properties of the concrete lining; and thickness of lining which was obtained by Ground Penetration Radar (GPR) tests. It was found that influencing factors causing longitudinal cracks in the lining were closely related with the construction condition of the primary support system, i.e. shotcrete, rockbolt, and steel-rib; crack occurrences were not much affected by the excavation patterns. As for the properties of concrete lining materials, occurrence of the longitudinal crack was mostly affected by the following three items: w/c ratio; contents of cement; and strength of lining. When estimating the lining thickness of the concrete lining by GPR tests and taking thickness effect into account in the statement assessment, it was concluded that increase of the index score by an average of 0.03 (ranging from 0.01 up to 0.071) is needed; a more realistic way of state assessment should be proposed in which the increased index score caused by lack of lining thickness should be taken into account.

• Journal of the Korean Society for Railway
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• v.20 no.1
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• pp.64-75
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• 2017

The role of a track subgrade is to provide bearing capacity and distribute load transferred to lower foundation soils. Track subgrade soils are usually compacted by heavy mechanical machines in the field, such that sometimes they are attributed to progressive residual settlement during the service after construction completion of the railway track. The progressive residual settlement generated in the upper part of a track subgrade is mostly non-recoverable plastic deformation, which causes unstable conditions such as track irregularity. Nonetheless, up to now no design code for allowable residual settlement of subgrade in a railway trackbed has been proposed based on mechanical testing, such as repetitive triaxial testing. At this time, to check the DOC or stiffness of the soil, field test criteria for compacted track subgrade are composed of data from RPBT and field compaction testing. However, the field test criteria do not provide critical design values obtained from mechanical test results that can offer correct information about allowable permanent deformation. In this study, a test procedure is proposed for permanent deformation of compacted subgrade soil that is used usually in railway trackbed in the laboratory using repetitive triaxial testing. To develop the test procedure, an FEA was performed to obtain the shear stress ratio (${\tau}/{\tau}_f$) and the confining stress (${\sigma}_3$) on the top of the subgrade. Comprehensive repetitive triaxial tests were performed using the proposed test procedure on several field subgrade soils obtained in construction sites of railway trackbeds. A permanent deformation model was proposed using the test results for the railway track.

• Journal of the Korea Concrete Institute
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• v.13 no.5
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• pp.430-437
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• 2001

Recently, there have been increased much concerns about repair and rehabilitation works for aged concrete structures. It is in particular known that due to repeated overburden vehicles, there are significantly increasing number of aged concrete bridge slabs, which are strongly needed to construct and rehabilitate by innovative construction method. The objective of this research is to develop the new construction method of concrete slab in bridge superstructure, which can contribute to minimize a traffic congestion during repair and rehabilitation works of aged concrete slab, and can sufficiently assure the quality through the minimization of in-situ works at the site. I-beams with punch holes, which are substituted instead of main reinforcing steels in concrete slabs, can be manufactured in accordance with the specification in the factory, and be preassembled into the panel. After erecting the preassembled panels in the site, concrete will be poured into the slab panel. This research is to investigate mechanical properties of I-beam with punch holes itself, and then to investigate structural properties of assembled I-beam panels through static test, of which result can be utilized for the development of the new constructional method for concrete slab in bridge superstructure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.301-306
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• 2016

In bridge performance assessments, a new load carrying capacity evaluation model of simple bridges was proposed, which is based on the developed simple support impact factor spectrum. In this paper, a conservative assumption that the inner span with the both ends fixed boundary condition is ideal for applying the impact factor response spectrum for continuous bridges. The impact factor response spectrum has been proposed based on this assumption. The response spectrum by comparing the numerical analysis result and actual measurement data verified the applicability. The analysis was loading the moving load of DB-24 in a six-span continuous bridge, which was the same as the actual measurement data, the dynamic response was measured in the fourth span. The frequency of the bridge was obtained by FFT on the acceleration response and the span-frequency of sample bridge was calculated by the frequency. The impact factor of the sample bridge was determined by applying the span-frequency of the bridge to the proposed response spectrum; it was similar to the result of comparing the actual measured impact factor. Therefore, the method using the impact factor response spectrum based on the frequency response of both ends-fixed beam was found to be applicable to an actual continuous bridge.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.1
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• pp.53-60
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• 2010

In constructing ILM(Incremental Launching Method) bridges, a launching nose is generally used in order to absorb temporary stress occurring during launching. The sectional forces of superstructure of ILM bridges, which occurs during launching, varies significantly according to the length, weight and stiffness of the launching nose. Thus in order to guarantee the safety of section of ILM bridges, the change of stress according to interaction behavior between launching nose and superstructure should be considered. However, the span division and span length are often decided based on previous cases in practice. It makes the design sections of launching nose are similar in spite of different projects. The designer's anxiety to optimize the launching nose to affect the optimum design of superstructure is also weak. In this study, an design formular to optimize the nose is proposed by using the analysis formular of nose-deck interaction and the design level of ILM bridges constructed on 00 Expressway is examined. According to the result of this study, the proposed design formulas are expected to make a significant contribution to section design that is economically efficient and at the same time guarantees the safety of the superstructure and launching noses of ILM bridges regardless of span length.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.10
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• pp.323-328
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• 2014

ZigBee based on the most vulnerable part of u-Healthcare system that uses the ZigBee communication is the wireless section. ZigBee communication sectors to identify vulnerabilities in this paper, we propose to compensate. ZigBee has been raised from the existing vulnerabilities organize and ZigBee also uses the 64bit address that uniquely identifies a vulnerability that was defined as exposure. And to prevent the exposure of a unique identifying address was used to address a temporary identification. ZigBee security services, the proposed system during the Network Key for encryption only use one mechanism of Residential Mode is used. Residential Mode on all nodes of the entire network because they use a common key, the key is stolen, your network's security system at a time are at risk of collapse. Therefore, in order to guard against these risks to the security policy Network Key updated periodically depending on the method used to. The proposed evaluation and comparative analysis of the system were exposed in the existing system can hide the address that uniquely identifies a public key Network Key also updated periodically, so that leaks can occur due to reduced risk.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.1
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• pp.67-77
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• 2008

Seismic isolation has been studied continuously as a solution of the seismic engineering to reduce the sectional forces and the damages of structures caused by earthquakes. To certify reliable design and installation of the seismic isolation systems, seismic isolation bearings should be fabricated under well planned quality control process, and proper evaluation tests for their seismic performance should be followed. In this study, shear property evaluation tests for the lead rubber bearings(LRB) and the rubber bearings(RB) were implemented and the temperature dependency tests were also implemented to evaluate the changes of shear properties according to the changes of temperature. After evaluation tests, the measured shear properties were compared to their design values and their deviation was analyzed comparing with the allowable error ranges specified in Highway Bridge Design Specifications. These results showed that a considerable number of isolation bearings have so large deviations from their design values that their error ranges were over or very close to the allowable ranges. And the test results for temperature dependency showed that the shear properties of isolation bearings would be changed in great degree by the change of temperature during their service period. If these two types of changes in their shear properties are superposed, it would possible that the changes of shear properties from their original design values are over than 50%.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.1
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• pp.117-126
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• 2022

Currently, the number of bridge structures in Korea is continuously increasing and enlarged, and the number of old bridges that have been in service for more than 30 years is also steadily increasing. Bridge aging is being treated as a serious social problem not only in Korea but also around the world, and the existing manpower-centered inspection method is revealing its limitations. Recently, various bridge damage detection studies using deep learning-based image processing algorithms have been conducted, but due to the limitations of the bridge damage data set, most of the bridge damage detection studies are mainly limited to one type of crack, which is also based on a close set classification model. As a detection method, when applied to an actual bridge image, a serious misrecognition problem may occur due to input images of an unknown class such as a background or other objects. In this study, five types of bridge damage including crack were defined and a data set was built, trained as a deep learning model, and an open set recognition-based bridge multiple damage recognition model applied with OpenMax algorithm was constructed. And after performing classification and recognition performance evaluation on the open set including untrained images, the results were analyzed.