• 한국수자원학회논문집
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• 제56권9호
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• pp.553-562
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• 2023

흰수마자(Gobiobotia naktongensis)는 멸종위기야생동물 I급 담수어류로 지정된 대한민국 고유종이다. 흰수마자가 최초로 발견된 낙동강의 지류 중 하나인 내성천은 고운 모래하상과 여울이 발달되어 과거 흰수마자에게 최적의 서식 환경을 제공했었다. 현재 영주댐이 건설되고 지자체가 과도한 하도준설을 시행하여, 댐하류 지역의 하상 조립화가 가속화되면서 흰수마자의 서식환경은 악화되고 있는 추세이다. 본 연구에서는 내성천 하상 입경 변화에 따른 흰수마자 서식처 적합도 변화 양상을 물리서식처 모형인 River2D를 활용하여 가중가용면적(Weight Usable Area, WUA)에 근거하여 분석하였다. 분석의 공간적 범위는 영주댐 하류 석탑교에서부터 회룡교까지의 구간이며, 하상 입경 변화는 2010년과 2020년에 각각 분석된 중앙입경을 이용하였다. 내성천의 2020년 하상 입경은 2010년 하상 입경보다 굵어졌으며 전반적으로 모래입자 조립화 현상이 뚜렷하였다. River2D 분석결과 전체 모의구간의 흐름 영역 면적 대비 흰수마자의 서식이 가능한 영역은 2010년에 약 0.75%에 불과하였고, 이마저도 2020년에는 하상조립화로 인해 0.55%로 감소하였다.

• 한국물환경학회지
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• 제31권5호
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• pp.460-467
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• 2015

We analyzed the formation of phytoplankton community and the occurences of odorus compound from benthic cyanobacteria in North, South Han-River, Paldang-Lake and Kyeongan-Stream sediments. Sediments were incubated in different water temperature. Akinetes were found (0~500 cells/g) with the highest number on sediment in Yangsoo railroad bridge (YC). The result showed that Anabaena ranged between $0.02{\sim}0.53{\times}10^3cells/mL$ in Sambong (SB), YC, Mukhyen-Stream (MS), Paldang-Lake (P2) and Kyeongan-Stream (KK). The total 68 taxa of phytoplankton were observed during the incubation period. A standing crop of phytoplankton was in the range of $0.13{\sim}8.97{\times}10^3cells/mL$ and Microcystis appeared in SB, YC, P2 and KK sites with $20{\sim}25^{\circ}C$ temperature. In South Han-River (P3), Oscillatoria tenuis was dominant at $25^{\circ}C$ temperature. The concentration of geosmin was the highest in SB-$15^{\circ}C$ (25.5 ng/L), and the concentration of 2-MIB was the highest in P3-$25^{\circ}C$ (286.8 ng/L). Odorous compounds were detected in all the temperature conditions from each site. Our results indicate that the dominant benthic cyanobacteria (O. tenuis, O. limosa, Phormidium tenue and Pseudanabaena limnetica) have high correlation with the occurrence odorous compounds and 2-MIB.

• Computers and Concrete
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• 제14권6호
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• pp.745-765
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• 2014

In this paper, it is aimed to determine the finite element model updating effects on the structural behavior of long span concrete highway bridges. Birecik Highway Bridge located on the 81stkm of Sanliurfa-Gaziantep state highway over Firat River in Turkey is selected as a case study. The bridge consist of fourteen spans, each of span has a nearly 26m. The total bridge length is 380m and width of bridge is 10m. Firstly, the analytical dynamic characteristics such as natural frequencies and mode shapes are attained from finite element analyses using SAP2000 program. After, experimental dynamic characteristics are specified from field investigations using Operational Modal Analysis method. Enhanced Frequency Domain Decomposition method in the frequency domain is used to extract the dynamic characteristics such as natural frequencies, mode shapes and damping ratios. Analytically and experimentally identified dynamic characteristics are compared with each other and finite element model of the bridge is updated to reduce the differences by changing of some uncertain parameters such as section properties, damages, boundary conditions and material properties. At the end of the study, structural performance of the highway bridge is determined under dead load, live load, and dynamic loads before and after model updating to specify the updating effect. Displacements, internal forces and stresses are used as comparison parameters. From the study, it is seen that the ambient vibration measurements are enough to identify the most significant modes of long span highway bridges. Maximum differences between the natural frequencies are reduced averagely from %46.7 to %2.39 by model updating. A good harmony is found between mode shapes after finite element model updating. It is demonstrated that finite element model updating has an important effect on the structural performance of the arch type long span highway bridge. Maximum displacements, shear forces, bending moments and compressive stresses are reduced %28.6, %21.0, %19.22, and %33.3-20.0, respectively.

• Smart Structures and Systems
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• 제6권4호
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• pp.373-388
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• 2010

The updated finite element model of K$\ddot{o}$m$\ddot{u}$rhan Highway Bridge on the Firat River located on the $51^{st}$ km of Elazi$\breve{g}$-Malatya highway is obtained by using analytical and experimental results. The 2D and 3D finite element model of the bridge is created by using SAP2000 structural analyses software, and the dynamic characteristics of the bridge are determined analytically. The experimental measurements are carried out by Operational Modal Analysis Method under traffic induced vibrations and the dynamic characteristics are obtained experimentally. The vibration data are gathered from the both box girder and the deck of the bridge, separately. Due to the expansion joint in the middle of the bridge, special measurement points are selected when experimental test setups constitute. Measurement duration, frequency span and effective mode number are determined by considering similar studies in literature. The Peak Picking method in the frequency domain is used in the modal identification. At the end of the study, analytical and experimental dynamic characteristic are compared with each other and the finite element model of the bridge is updated by changing some uncertain parameters such as material properties and boundary conditions. Maximum differences between the natural frequencies are reduced from 10% to 2%, and a good agreement is found between natural frequencies and mode shapes after model updating.

• Journal of the Korean Institute of Landscape Architecture International Edition
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• 제1호
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• pp.202-207
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• 2001

Covering an area of about 39 ha, Qingming Shanghe Park is located in the northwest of Kaifeng, formerly the capital of seven dynasties in China. It is intended to serve as a tourist attraction based on a painting 〃Qingming Festival at Riverside〃 by Zhang Zeduan of the Northern song Dynasty, which vividly illustrates a real life on the both sides of the Bian River as well as in the urban area, Kaifeng, in early Spring. The park is a collection of varied buildings such as shops, restaurants, tea-houses, theaters, and hotels in the North song style, with an introduction of the history of Kaifeng, this paper examines design philosophy and methodology of the park, and discusses the creative design of the first stage development known as known as The South Area of the park. Marked by the Rainbow Bridge and the City Gate, the South Area is divided into three parts, the rural, suburban, and urban parts which are organized according to the spatial order showed in the painting. The South Area proves to be very successful because of its amazing sense of history and interesting folk performance. Furthermore, the preliminary 9planning of the second stage development known as The North Area is presented with references to culture, history and customs. The North Area is proposed to include the Old Sports & Games Garden, the Exhibition Garden, and the Hot Spring Garden with an appearance of the imperial gardens in the Northern Song, integrated with participation of old sports and games, display of old science & technology achievements, and enjoyment of hot spring bath.

• 한국지형학회지
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• 제19권4호
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• pp.27-37
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• 2012

본 연구는 강원도 철원군 명성산 화강암과 현무암 용암대지 사이의 접촉대인 한탄강 승일교 인근 지역의 독특한 경관을 형성하고 있는 화강암 하천 침식 및 퇴적 지형과 풍화 지형 분석을 다루고 있다. 주요 화강암 지형으로서는 심층풍화된 구릉, 면상침식지형, 고지형면 및 고토양, 하천작용과 관련된 미지형으로 돌개구멍과 그루브, 램 파트형의 암괴, 사주와 사력퇴, 그리고 구하상 등이 있다. 그리고 풍화가 덜 진전된 구릉의 일부로 하천의 측방이동을 방해하는 화강암 하식애 지형이 있다.

• Structural Engineering and Mechanics
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• 제88권4호
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• pp.311-322
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• 2023

Riverine flood is one of the critical natural threats to river-crossing bridges. As floods are the most-occurred natural hazard worldwide, survival probability of bridges due to floods must be assessed in a speedy but precise manner. In this regard, the paper presents a reliability-based approach for a rapid assessment of failure probability of vulnerable bridge components under floods. This robust method is generic in nature and can be applied to both concrete and steel girder bridges. The developed methodology essentially utilizes limit state performance functions, expressed in terms of capacity and flood demand, for probable failure modes of various vulnerable components of bridges. Advanced First Order Reliability Method (AFORM), Monte Carlo Simulation (MCS), and Latin Hypercube Simulation (LHS) techniques are applied for the purpose of reliability assessment and developing flood fragility curves of bridges in which flow velocity and water height are taken as flood intensity measures. Upon validating the proposed method, it is applied to a case study bridge that experiences the flood scenario of a river in Gujarat, India. Research outcome portrays how effectively and efficiently the proposed reliability-based method can be applied for a quick assessment of flood vulnerability of bridges in any flood-prone region of interest.

• 환경영향평가
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• 제9권2호
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• pp.143-153
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• 2000

This study was performed to investigate the heavy metal contents and distribution in soil, sediment, and rice from the downstream area of ManKyeong and DongJin River. Of the sites on Mankyeong river area, site M-1(Mokchon bridge) showed the highest average contents of Cd, Cr and Pb in paddy soil. In DongJin river area, site D-3(Munpo) and D-4(Gerjeonri) showed relatively high level of average contents of Cr, Pb and Zn in paddy soil. The average contents of heavy metals in brown rice from ManKyeong river area were 0.10mg/kg for Cd, 0.99mg/kg for Cr, 2.07mg/kg for Pb, 4.44mg/kg for Cu and 32.03mg/kg for Zn while those in brown rice from DongJin river area were 0.14mg/kg for Cd, 0.74mg/kg for Cr, 1.78mg/kg for Pb, 4.57mg/kg for Cu and 33.60mg/kg for Zn. Zn showed the highest transportation-rate from paddy soil to brown rice while Pb showed the lowest. From the results of heavy metal analysis in sediments, the average contents of Cd, Cr, Pb and Cu were generally high in site M-5(Euonri) and D-4(Gerjeonri), the most downstream sites in Mankyeong river and DongJin river, respectively.

• 한국물환경학회지
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• 제28권6호
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• pp.890-895
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• 2012

Duration curves describe the percentage of time that a certain water quality (total/fecal coliform (=TC/FC)) or discharge is exceeded. The curves methodology are usually based on daily records and are useful in estimating how many days per year and event will be exceeded. The technique was further applied to estimated TC/FC loading to the Geumho River, using the daily mean flow rate and TC/FC concentration data during January, 2001 and December, 2011 for the Geumhogang6 (=Seongseo water level station) where an automated monitoring station is located in Gangchang-bridge. Low flow of the Seongseo (=11.1 cms) was equivalent to 75.3% on an exceedance probability scale. Load Duration curve for TC/FC loading at the Seongseo was constructed. Standard load duration curve was constructed with the water quality criteria for class III (TC/FC concentration = 5000/1000 CFU/ 100 mL). By plotting TC/FC observed load duration curve with standard load duration curve, it could be revealed that water quality do not meet the desired water quality for 68.8/11.2% on an exceedance probability scale. IF linear correlation between flow rate and coliform concentration is assumed, it can be interpreted that water quality exceed desired criteria when daily average flow rate is over 11.9/109.9 cms.

• Structural Engineering and Mechanics
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• 제42권2호
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• pp.229-245
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• 2012

Bridge vibration displacements have been directly measured by LVDTs (Linear Variable Differential Transformers) or laser equipment and have also been indirectly estimated by an algorithm of integrating measured acceleration. However, LVDT measurement cannot be applied for a bridge crossing over a river or channel and the laser technique cannot be applied when the weather condition is poor. Also, double integration of accelerations may cause serious numerical deviation if the initial condition or a regression process is not carefully controlled. This paper presents an algorithm of estimating bridge vibration displacements using vibration strains measured by FBG (Fiber Bragg Grating) sensors and theoretical mode shapes of a simply supported beam. Since theoretically defined mode shapes are applied, even high modes can be used regardless of the quality of the measured data. In the proposed algorithm, the number of theoretical modes is limited by the number of sensors used for a field test to prevent a mathematical rank deficiency from occurring in computing vibration displacements.89The proposed algorithm has been applied to various types of bridges and its efficacy has been verified. The closeness of the estimated vibration displacements to measured ones has been evaluated by computing the correlation coefficient and by comparing FRFs (Frequency Response Functions) and the maximum displacements.