• 한국환경보건학회지
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• 제28권2호
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• pp.23-39
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• 2002

This study focuses on the structure of geographical conditions, the riverbed, the meterological and atmospheric examination, the ecological environment, the food chain and the ecosystem, in order to establish a basic plan for preparing a natural learning area of environmental ecosystem in Bukchun and its surroundings, Gyeongju. The results could be summarized as follows. Bukchun is a first grade which extends 6km along the road from Bomun bridge to the junction of Hyungsangang. The basin area is 7.10$\textrm{km}^2$ and the slope is 1/200~1/300. Gyeongju has good atmospheric conditions, i.e. SO$_2$0.011 ~0.017ppm, CO 0.8~ 1.5ppm, NO$_2$0.013~0.019ppm, $O_3$0.013~0.020ppm, TSP 85~142$\mu\textrm{g}$/㎥, PM-10 47~90$\mu\textrm{g}$/㎥ and Pb 0.057 ~0.129$\mu\textrm{g}$/㎥, which is below the annual and daily averages, and is little lower than those of Pohang and Ulsan. The ecosystem of Bukchun is based on the structure of the food chain, which includes birds such as the grey and white herons at the top of the food chain. This study also considers the development of the river's in terms of culture, environment and ecology concept.

• 한국정보통신학회논문지
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• 제13권6호
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• pp.1051-1057
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• 2009

교량감시, 문화재감시, 하천감시, 노약자보호, 도시관제 및 환경감시 등 많은 분야에서 USN(Ubiquitous Sensor Network)을 이용한 서비스가 시작되고 있고, USN을 구현하기 위해서는 RF 송수신기가 반드시 필요하다. 본 논문은 2.4GHz 대역에서 동작하는 센서노드용 RF 송수신기의 설계 및 제작에 대해서 기술한다. RF 송수신기의 설계과정으로 AGC의 범위 설정과 송수신기의 설계 과정이 기술되어 있다. 또한 설계된 RF 송수신기를 제작하여 성능을 시험하였으며, 수신감도, 동작범위, 주파수 안정도, 위상잡음, 송신전력, 송신대역평탄도와 스펙트럼 마스크의 측정 결과가 기술되어 있다.

• 한국물환경학회지
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• 제22권2호
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• pp.349-357
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• 2006

Nowadays, the discharges of urban streams during dry season are depleted because the hydrologic cycle in the watershed has been destroyed due to the expansion of the impermeable area, the excessive groundwater pumping, climate change, and so forth. The streamflow depletion may bring out severe water quality problems. This research are to investigate the hydrologic characteristics and to develop a technology to restore sound hydrologic cycle of Anyangcheon watershed. For the hydrological cycle analysis of the Anyangcheon watershed, continuous simulations of urban runoff were performed for the upstream basin of Gocheok bridge whose basin area covered 4/5 of the whole catchment area. The increase of impervious area by urbanization was analysed and its effect on urban runoff was evaluated. The SWMM 5 (Storm Water Management Model 5) was used for the continuous simulation of urban runoff. The analysis results of urbanization effect on runoff are as follows: the surface runoff in 2000 increases to 65% of the whole precipitation whereas the surface runoff in 1975 amounts to 50% of the precipitation; the groundwater runoff in 2000 amounts to 7% and shows 6% decrease during the period from 1975 to 2000.

• 한국물환경학회지
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• 제22권5호
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• pp.815-823
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• 2006

The hydrologic cycle in urban catchment has been changed due to the expansion of impervious area by rapid urban development. In this study, the SWMM 5 (Storm Water Management Model 5) model was used to simulate the hydrologic cycle of the Dorimcheon catchment which suffers from the distorted hydrologic cycle as a typical urban catchment. This study compare continuous simulation of urban runoff combining the channel and sewer system with that of channel only in the Dorimcheon catchment. Continuous simulations of urban runoff were performed for the upstream basin of Dorim bridge. The urban impervious regions were processed by the land use analysis from LANDSAT_TM images. It was performed from 1975 to 2000 for every five years. Surface, groundwater and wastewater runoffs were additionally included in the simulations one at a time. Such simulations made it possible to evaluate those components quantitatively. The result of continuous simulation of urban runoff combining the channel and sewer system is that peak flow and recession are well simulated. The analysis results of urbanization effect on runoff are as follows: the surface runoff in 2000 increases to 64% of the whole precipitation whereas the surface runoff in 1975 amounts to 46% of the precipitation; the groundwater runoff in 2000 amounts to 6% and shows 8% decrease during the period from 1975 to 2000.

• 한국방재학회 논문집
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• 제9권4호
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• pp.91-97
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• 2009

하천을 횡단하는 구조물들은 흐름을 변화시킬 뿐 아니라, 산지 및 중소하천에서 유송잡물로 인한 수위 상승의 원인을 제공하기도 한다. 이번 연구에서는 유속 및 경사 등의 하천특성인자와 교각의 영향으로 변화되는 흐름을 2차원 모형으로 분석하였다. 또한 강우로 인해 변화된 유량이 흐름에 미치는 영향도 비교하였다. 하도내의 유속은 SMS (Surface water Modeling System) 및 RMA2 모형을 통해서 분석할 수 있었으며, 경사가 크고, 하도의 폭이 좁은 구간에서 비교적 유속이 큰 것으로 나타났다. 또한 교각 주변에서는 교각과 교각 사이의 중심부에서 유속이 가장 크게 나타났다. 강우로 인해 증가된 유량은 유속을 증가시키고 흐름 분포를 현저하게 변화시키는 것을 확인할 수 있었다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 추계 학술논문 발표대회
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• pp.179-182
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• 2009

Concrete containing styrene-butadiene latex is widely used, nowadays, as a protective system for bridge. Latex modification mortar have taken advantage of latex modification concrete advantage that is used in existing, Also, when repair, protection and sticking performance of concrete overlay waterproof agent were known as that are good. Replace and experimented from fine aggregate to recycled aggregate to secure economic performance than existing latex modification concrete. Recycled fine aggregate has low quality because it contains large amount of old mortar. So, its usage is limited to a lower value-add, such as the roadbed material etc. This study is purposed to improve the performance of mortar made of recycled fine aggregate. For this, recycled aggregate mortar was produced with latex, and fluidity, strength were examined. Test result indicate that mortar using recycled fine aggregate is higher compressive and flexural strength than mortar using river sand.

• Smart Structures and Systems
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• 제24권5호
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• pp.607-616
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• 2019

The video deflectometer based on digital image correlation is a non-contacting optical measurement method which has become a useful tool for characterization of the vertical deflections of large structures. In this study, a novel imaging model has been established which considers the variations of pitch angles in the full image. The new model allows deflection measurement at a wide working distance with high accuracy. A monocular video deflectometer has been accordingly developed with an inclination sensor, which facilitates dynamic determination of the orientations and rotation of the optical axis of the camera. This layout has advantages over the video deflectometers based on theodolites with respect to convenience. Experiments have been presented to show the accuracy of the new imaging model and the performance of the monocular video deflectometer in outdoor applications. Finally, this equipment has been applied to the measurement of the vertical deflection of Yingwuzhou Yangtze River Bridge in real time at a distance of hundreds of meters. The results show good agreement with the embedded GPS outputs.

• Smart Structures and Systems
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• 제10권1호
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• pp.33-46
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• 2012

To reduce the vibration of cable-stayed bridges, conventional magnetorheological (MR) damper control system (CMRDS), with separate power supply, sensors and controllers, is widely investigated. In this paper, to improve the reliability and performance of the control system, one adaptive MR damper control system (AMRDS) consisting of MR damper and piezoelectric energy harvester (PEH) is proposed. According to piezoelectric effect, PEH can produce energy for powering MR damper. The energy is proportional to the product of the cable displacement and velocity. Due to the damping force changing with the energy, the new system can be adjustable to reduce the cable vibration. Compared with CMRDS, the new system is structurally simplified, replacing external sensor, power supply and controller with PEH. In the paper, taking the N26 cable of Shandong Binzhou Yellow River Bridge as example, the design method for the whole AMRDS is given, and simple formulas for PEH are derived. To verify the effectiveness of the proposed adaptive control system, the performance is compared with active control case and simple Bang-Bang semi-active control case. It is shown that AMRDS is better than simple Bang-Bang semi-active control case, and still needed to be improved in comparison with active control case.

• Smart Structures and Systems
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• 제26권6호
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• pp.781-796
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• 2020

Prediction of total sediment load is essential in an extensive range of problems such as the design of the dead volume of dams, design of stable channels, sediment transport in the rivers, calculation of bridge piers degradation, prediction of sand and gravel mining effects on river-bed equilibrium, determination of the environmental impacts and dredging necessities. This paper is aimed to investigate and predict the total sediment load of the Wadi Arbaat in Eastern Sudan. The study was estimated the sediment load by separate total sediment load into bedload and Suspended Load (SL), independently. Although the sediment records are not sufficient to construct the discharge-sediment yield relationship and Sediment Rating Curve (SRC), the total sediment loads were predicted based on the discharge and Suspended Sediment Concentration (SSC). The turbidity data NTU in water quality has been used for prediction of the SSC in the estimation of suspended Sediment Yield (SY) transport of Wadi Arbaat. The sediment curves can be used for the estimation of the suspended SYs from the watershed area. The amount of information available for Khor Arbaat case study on sediment is poor data. However, the total sediment load is essential for the optimal control of the sediment transport on Khor Arbaat sediment and the protection of the dams on the upper gate area. The results show that the proposed model is found to be considered adequate to predict the total sediment load.

• Computers and Concrete
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• 제33권5호
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• pp.573-594
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• 2024

This article presents a research study, with both laboratory and field tests, of a deep foundation in a markedly anisotropic medium. Particularly it has focused on the evaluation of the behavior of a pile, one meter in diameter, embedded in a rocky environment with difficult conditions, in the Flysch of the Spanish city of San Sebastián. To carry out the research, the site of a bridge over the Urumea River was chosen, which was supported by pre-excavated reinforced concrete piles. 4 borings were carried out, by the rotation and washing method, with continuous sampling and combined with flexible dilatometer tests. In the field, an Osterberg load test (O-cell) was performed, while in the laboratory, determinations of natural moisture, natural unit weight, uniaxial compressive strength (UCS), point load strength (PLS), compressive wave propagation velocity (V_c) and also triaxial and direct shear tests were carried out. The research results indicate the following: a) the empirical functions that correlate the UCS with the PLS are not always linear; b) for the studied Flysch it is possible to obtain empirical functions that correlate the UCS with the PLS and with the V_c; c) the bearing capacity of the studied Flysch is much greater than if it is evaluated by different load capacity theories; d) it is possible to propose an empirical function that allows evaluating the mobilized shear strength (τ_m), as a function of the UCS and the displacement relative of the pile (δ_r).