• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.530-535
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• 2005

To monitor the flood level under heavy rainfall and the scour at railroad bridge, the system, which can effectively collect, store and transmit the data, is developed and applied to the field. The results in this study are as follows. 1) Monitoring for water level and scour depth is well done in view of the recording velocity and the accuracy of data which are measured. 2) This system is based on the web, internet and it is able to collect the realtime data and to analyze the risk. 3) When water level excesses the limit of danger level of a river on which railroad bridge is located, or when scour depth and angle of inclination of pier is increased, the scenario for early warning signal which sends to managers at central traffic control and drivers of trains is automatically made. It is judged that this system secures the safety of railroad and protects lives of train passengers as the warning signal sends to running train in advance at risky situation of railroad bridge under heavy rainfall.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 봄 학술발표회 논문집
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• pp.245-248
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• 2001

During the core drilling for the design of a railway bridge crossing over the inferred fault system along the river, fracture zone, extends vertically more than the bottom of borehole, filled with fault gouge was found. The safety of bridge could be threatened by the excessive subsidence or the reduced bearing capacity of bedrock, if a fault would be developed under or around the pier foundation. Thus, a close examination of the fault was required to rearrange pier locations away from the fault or to select a reinforcement method if necessary. Geophysical methods, seismic reflection method and electrical resistivity survey over the water covered area, were applied to delineate the weak zone associated with the fault system. The results of geophysical survey clearly showed a number of faults extending vertically more than 50m. Reinforcement was not desirable because of the high cost and the water contamination, etc. The pier locations were thus rearranged based on the results of geophysical surveys to avoid the undesirable situations, and additional core drillings on the rearranged pier locations were carried out. The bedrock conditions at the additional drilling sites turned out to be acceptable for the construction of piers.

• Steel and Composite Structures
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• 제42권4호
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• pp.489-499
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• 2022

This paper proposes a numerical optimization method to design the mesoscale architecture of textile composite for simultaneously enhancing mechanical and thermal properties, which compete with each other making it difficult to design intuitively. The base cell of the periodic warp and fill yarn system is served as the design space, and optimal fibre yarn geometries are found by solving the optimization problem through the proposed method. With the help of homogenization method, analytical formulae for the effective material properties as functions of the geometry parameters of plain-woven textile composites were derived, and they are used to form the inverse homogenization method to establish the design problem. These modules are then put together to form a multiobjective optimization problem, which is formulated in such a way that the optimal design depends on the weight factors predetermined by the user based on the stiffness and thermal terms in the objective function. Numerical examples illustrate that the developed method can achieve reasonable designs in terms of fibre yarn paths and geometries.

• 한국구조물진단유지관리공학회 논문집
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• 제12권3호
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• pp.63-70
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• 2008

본 연구의 목적은 강원도 산악지역에서 교량 설계 지침 개발에 있다. 2002년 태풍 루사, 2003년 매미, 2006년 에위니아에 이은 7월 집중호우로 강원도 산악지역에서는 큰 피해를 당한 바 있다. 이런 피해의 원인은 강원도 산악지역에 위치하는 하천의 지역적, 지형학적 조건을 고려하지 못한 부분적인 이유도 있는 것으로 판단된다. 교량피해의 대부분은 교각과 교대의 기초부분 세굴(침식) 때문에 발생되었다. 다른 이유로는 고사목, 나뭇가지 및 부유잡물 등이 교각과 상판에 걸려서 물의 흐름을 어렵게 만들거나 차단 시켜서 발생되었다. 수해현장의 피해 형태와 원인 등을 분석하여 이로부터 설계 지침을 제시하였다.

• 대한토목학회논문집
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• 제38권4호
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• pp.537-545
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• 2018

설계홍수량 산정 시 도달시간과 같은 시간매개변수의 결정은 매우 중요한 요소이다. 도달시간은 주로 홍수 및 하천관리를 위해 이용되고 있으며, 평수기의 도달시간은 하천의 유지유량 및 이수관리를 위해 이용되고 있다. 자연하천에 대한 도달시간 산정은 주로 유역의 지형학적 인자를 기반으로 산정하고 있으며, 지형학적 인자 이외에 유출곡선지수, 유속, 강우강도의 인자를 고려하여 도달시간을 산정하고 있다. 그러나 재현기간별 강우조건과 토양함수상태를 함께 고려한 도달시간의 산정연구는 부재한 상황이다. 따라서 본 연구는 재현기간별 강우조건과 토양함수상태를 고려하여 임진강의 황강댐과 임진교 수위관측소 구간을 자연하천으로 설정한 경우와 황강댐의 방류량 조건에 따라 임진교 수위관측소에 도달하는 경우로 구분하여 도달시간을 산정하였다. 자연하천으로 설정한 구간에 대해서는 기 개발된 도달시간 산정방법과 비교 검토를 통해 결과를 입증하였으며, 이를 토대로 황강댐의 방류량 조건별 도달시간을 산정하였다. 본 연구에서 제시된 도달시간은 임진강 유역의 홍수관리와 황강댐 방류시 위험에 대비할 수 있는 시간을 확보할 수 있다.

• 조명전기설비학회논문지
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• 제20권6호
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• pp.1-8
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• 2006

본 연구는 휘도측정장비인 CS-100과 ProMetric 1400을 활용하여 조망점의 변화에 따른 교량 경관조명의 휘도를 분석한 것이다. 이를 위하여 경관조명이 적용된 한강의 교량4개를 교량형태별로 선정하고 조망유형에 따라 한강둔치에서 바라본 조망(투시뷰), 교량주변 건물에서 바라본 조망(건물뷰), 그리고 교량 위 주행자가 바라본 조망(주행뷰) 등 3가지로 분류하였다. 연구대상의 주변하늘, 강물표면, 상부구조물, 상판측면 그리고 교각에 대한 휘도분포를 측정하였다. 분석결과, 광진교와 동호대교는 투시뷰의 휘도가 높게 나타났으며, 올림픽대교와 동작대교는 건물뷰의 휘도가 높게 나타났다. 따라서 거더교와 같이 상부구조물이 없는 교량에서는 투시뷰가, 사장교 및 아치교와 같이 상부 구조물이 있는 교량에서는 건물뷰가 경관조명의 특성을 크게 반영하는 휘도분포가 강하게 나타났다.

• Structural Engineering and Mechanics
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• 제70권2호
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• pp.143-152
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• 2019

In this study, stochastic responses of a cable-stayed bridge subjected to the spatially varying earthquake ground motion are investigated for variable local soil cases and wave velocities. Quincy Bay-view cable-stayed bridge built on the Mississippi River in Illinois, USA selected as a numerical example. The bridge is composed of two H-shaped concrete towers, double plane fan type cables and a composite concrete-steel girder deck. The spatial variability of the ground motion is considered with the coherency function, which is represented by the components of incoherence, wave-passage and site-response effects. The incoherence effect is investigated by considering Harichandran and Vanmarcke model, the site-response effect is outlined by using hard, medium and soft soil types, and the wave-passage effect is taken into account by using 1000, 600 and 200 m/s wave velocities for the hard, medium and soft soils, respectively. Mean of maximum response values obtained from the analyses are compared with those of the specific cases of the ground motion model. It is concluded that the obtained results from the bridge model increase as the differences between local soil conditions cases of the bridge supports change from firm to soft. Moreover, the variation of the wave velocity has important effects on the responses of the deck and towers as compared with those of the travelling constant wave velocity case. In addition, the variability of the ground motions should be considered in the analysis of long span cable-stayed bridges to obtain more accurate results in calculating the bridge responses.

• Wind and Structures
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• 제38권1호
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• pp.43-58
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• 2024

To ensure the flutter stability of three-tower suspension bridges under skew wind, by using the computational procedure of 3D refined flutter analysis of long-span bridges under skew wind, in which structural nonlinearity, the static wind action(also known as the aerostatic effect) and the full-mode coupling effect etc., are fully considered, the flutter stability of a three-tower suspension bridge-the Taizhou Bridge over the Yangtze River in completion and during the deck erection is numerically investigated under the constant uniform skew wind, and the influences of skew wind and aerostatic effects on the flutter stability of the bridge under the service and construction conditions are assessed. The results show that the flutter critical wind speeds of three-tower suspension bridge under service and construction conditions fluctuate with the increase of wind yaw angle instead of a monotonous cosine rule as the decomposition method proposed, and reach the minimum mostly in the case of skew wind. Both the skew wind and aerostatic effects significantly reduce the flutter stability of three-tower suspension bridge under the service and construction conditions, and the combined skew wind and aerostatic effects further deteriorate the flutter stability. Both the skew wind and aerostatic effects do not change the evolution of flutter stability of the bridge during the deck erection, and compared to the service condition, they lead to a greater decrease of flutter critical wind speed of the bridge during deck erection, and the influence of the combined skew wind and aerostatic effects is more prominent. Therefore, the skew wind and aerostatic effects must be considered accurately in the flutter analysis of three-tower suspension bridges.

• Ocean and Polar Research
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• 제31권1호
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• pp.71-76
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• 2009

Drastic changes in the water quality and phytoplankton community of the new Saemankeum Lakeduring the first decade following the construction of the Saemankeum Sea Wall has been considered to be unavoidable. Input of eutrophicated water through the Mankyeong River and Dongjin River might produce more direct effects on the water quality and phytoplankton community, which lead us to launch a long-term semi-weekly investigation at the "Mankyeong Bridge" monitoring point to resolve its short-term effect as well as long-term stabilization of the ecosystem in the new Saemankeum Lake. During 15 months starting from June 2006, the water temperature varied in accordance with the typical seasonal variations in temperate on the coasts, and no significant daily variations evoked by tidal cycle could be detected. However, there was an inverse relationship between seasonal precipitation and salinity even though the range in annual variation was drastically reduced right after the construction of the Saemankeum Sea Wall. Species richness in the phytoplankton community was also reduced due to the narrowed annual range of salinity, which would eliminate the mid-high salinity species from the Mankyeong Bridge monitoring point. Similarly, species diversity was decreased with increased dominance of the phytoplankton community after the construction. Between the two summer seasons during the present study, species diversity was higher in 2007 than in 2006, which might indicate the early stage of a gradual stabilization in the ecosystem including the phytoplankton community at the monitoring station. The phytoplankton community thus needs to be monitored on a long-term basis to identify indirect signals that can be used to assess the stability of the ecosystem in the young Saemankeum Lake.

• 한국환경보건학회지
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• 제28권5호
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• pp.13-21
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• 2002

This study analyzed the characteristic of basic river structure, a flood level, the tree planting recommendation and syn thetic design, in order to establish a basic plan for preparing a natural practical area of environmental ecosystem at Bukchun and its surroundings. It was also investigated based on the opinion of citizens, geographical condition and the equipment/utilization examination of Bukchun which were included ecological circumstances, and thus provided a composite item for managing the natural river. This study also considered the development of the river in terms of culture, environment and ecology concept. The results were summarized as followed. Bukchun showed that the speed of a funning fluid is very fast on a period of flood. but very slow in a period of water shortage about 0.02 m/s. To prevent the speed change of a running fluid by a steep slope in a riverbed, there established Dongchun sluice gates under a bridge, including three sluice gates under a bridge, but there occurred extremely a riverbed erosion and corrosion section. The result of comparison between real flood degree and prediction flood data, there should perform a countermeasure the riverbed structure regulation of this area. Also, it was needed an exhaustive flood management in summer. According to the Bukchun and Hyungsangang riverbed investigation, there were needed preparation for natural/practical area and ecology Park development in the future. This study was investigated tree Planting/flower/blossom around the Bukchun and its surroundings. It was recommended willow, Italian poplar, bamboos and cherry blossoms in the Hyungsangang and Bukchun. There exist together historical space, environment space iud have enough possibility both natural learning space and civil rest space. And, it is possible to compose ecology natural learning and experimental area.