고속도로 노면 강우유출 오염부하 원단위 산정

강희만,이두진,배우근 대한상하수도학회 2012 상하수도학회지 Vol.26 No.1

Impervious surface increase due to urbanization, one of the leading causes of pavement increased the runoff coefficient, peak flow,and reducing the infiltration flow and thereby causing flooding and river erosion is occurring in aquatic ecosystems are known to impair. This study aimed to classify use type of detailed land into the road, reststop, tollgates and etc. focused on major domestic highways, to understand the characteristics of rainfall runoff pollutants and to calculate applicable unit pollution load. Because of high runoff coefficient and short travel time to drainage. first flush occurred clearly. Average EMCs of runoff in the highway was investigated as TSS 108.47 ㎎ / L, COD 28.16 ㎎ / L, BOD 13.61 ㎎ / L, TN 6.38 ㎎ / L, TP 0.03 ㎎ / L, Cu 118.17 ㎍ / L, Pb 345.3 ㎍ / L, Zn 349.47 ㎍ / L. Unit pollution loads calculated by detailed land use area of highways based on average annual rainfall, EMCs, applicable basin areas and etc. were 46.6 kg/km2/day of BOD, 1.4 kg/km2/day of TP, 8.81 kg / km2/day of TN and these were BOD 50.8%, TP 66.7%,TN 64.4%in comparison of the unit pollution loads which applies fallow land standards of the TMDL(Total Maximum Daily Load). It was considered that discharged loads can be excessively calculated in case highway non-point management plans based on unit pollution load of the current land standard. Impervious surface increase due to urbanization, one of the leading causes of pavement increased the runoff coefficient, peak flow,and reducing the infiltration flow and thereby causing flooding and river erosion is occurring in aquatic ecosystems are known to impair. This study aimed to classify use type of detailed land into the road, reststop, tollgates and etc. focused on major domestic highways, to understand the characteristics of rainfall runoff pollutants and to calculate applicable unit pollution load. Because of high runoff coefficient and short travel time to drainage. first flush occurred clearly. Average EMCs of runoff in the highway was investigated as TSS 108.47 ㎎ / L, COD 28.16 ㎎ / L, BOD 13.61 ㎎ / L, TN 6.38 ㎎ / L, TP 0.03 ㎎ / L, Cu 118.17 ㎍ / L, Pb 345.3 ㎍ / L, Zn 349.47 ㎍ / L. Unit pollution loads calculated by detailed land use area of highways based on average annual rainfall, EMCs, applicable basin areas and etc. were 46.6 kg/km2/day of BOD, 1.4 kg/km2/day of TP, 8.81 kg / km2/day of TN and these were BOD 50.8%, TP 66.7%,TN 64.4%in comparison of the unit pollution loads which applies fallow land standards of the TMDL(Total Maximum Daily Load). It was considered that discharged loads can be excessively calculated in case highway non-point management plans based on unit pollution load of the current land standard.

Laminated element analysis to predict the shear strength of concrete beams under distributed and concentrated loads

Kim, Jong-Chan,Choi, Kyoung-Kyu Elsevier 2017 ENGINEERING STRUCTURES Vol.152 No.-

<P><B>Abstract</B></P> <P>In the present study, an advanced analytical method was developed to evaluate the shear strength of slender concrete beams under distributed and concentrated transverse loads. The concrete shear capacity of the concrete beams is mainly provided by the compression zone of intact concrete since the tension zone of the concrete beams is severely damaged by flexural cracks before shear failure. The concrete shear capacity is evaluated based on concrete material failure criteria addressing combined compressive normal and shear stresses in the compression zone along the critical shear crack surface. For complete analysis, laminated elements are applied to take into account the stress variation in each location of the compression zone. The proposed analytical method can be used not only to predict the shear strength, but also the location and the angle of the critical shear crack. The shear strength is predicted using the proposed method, and the results are compared to those of an experiment, covering a wide range of design parameters. In addition, analytical studies were performed for analytical beam models subjected to distributed and concentrated loads. Based on the analysis results, the effect of various parameters including the loading type (distributed and concentrated transverse loads) on the shear strength and the critical shear crack was investigated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Developed an analytical method to evaluate the shear strength of concrete beams. </LI> <LI> Adopted laminated elements to consider variations in compressive stress. </LI> <LI> Predicted the shear strength and critical shear crack of concrete beams. </LI> <LI> The method is applicable to beams under various loading and boundary conditions. </LI> </UL> </P>

Grid Based Nonpoint Source Pollution Load Modelling

Abolghasem Sadeghi Niaraki,Jae-Min Park,Kyehyun Kim,Chulyong Lee 대한공간정보학회 2007 한국지형공간정보학회 학술대회 Vol.2007 No.6

The purpose of this study is to develop a grid based model for calculating the critical nonpoint source (NPS) pollution load (BOD, TN, TP) in Nak-dong area in South Korea. In the last two decades, NPS pollution has become a topic for research that resulted in the development of numerous modeling techniques. Watershed researchers need to be able to emphasis on the characterization of water quality, including NPS pollution loads estimates. Geographic Information System (GIS) has been designed for the assessment of NPS pollution in a watershed. It uses different data such as DEM, precipitation, stream network, discharge, and land use data sets and utilizes a grid representation of a watershed for the approximation of average annual pollution loads and concentrations. The difficulty in traditional NPS modeling is the problem of identifying sources and quantifying the loads. This research is intended to investigate the correlation of NPS pollution concentrations with land uses in a watershed by calculating Expected Mean Concentrations (EMC). This work was accomplished using a grid based modelling technique that encompasses three stages. The first step includes estimating runoff grid by means of the precipitation grid and runoff coefficient. The second step is deriving the gird based model for calculating NPS pollution loads. The last step is validating the gird based model with traditional pollution loads calculation by applying statistical t-test method. The results on real data, illustrate the merits of the grid based modelling approach. Therefore, this model investigates a method of estimating and simulating point loads along with the spatially distributed NPS pollution loads. The pollutant concentration from local runoff is supposed to be directly related to land use in the region and is not considered to vary from event to event or within areas of similar land uses. By consideration of this point, it is anticipated that a single mean estimated pollutant concentration is assigned to all land uses rather than taking into account unique concentrations for different soil types, crops, and so on.

Failure Mode of Orthotropic Two-way Composite Slab under Concentrated Load

Yulin Zhan,Wenfeng Huang,Yu Qiao,Zhouyuan Xu,Renda Zhao 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.12

Ordinary reinforced concrete two-way slabs generally suffer from punching failure under concentrated loads, which is a brittle failure and unfavorable to the structures. The composite slabs with steel sheets and PBL (perfobond rib) shear connectors have been applied for reducing the damage to bridge decks from vehicles. Although it is widely used on bridges, the failure mode of the orthotropic two-way composite slabs has rarely been studied when subject to concentrated loads. Accordingly, static loading tests with concentrated forward central load was carried out on 4 two-way composite slabs, in which the effects of the thickness of steel bottom sheets and concrete plates and spacing of PBL shear connectors on mechanical properties were investigated. The test results show that about 12% of the ultimate bearing capacity decreases when the perfobond ribs are spaced farther apart from 180 mm to 240 mm or the thickness of steel bottom sheets is reduced from 10 mm to 8 mm. And the bearing capacity drops by 38.2% when the thickness of concrete plates decreases by 30 mm. The steel-concrete composite slabs exhibit clear bidirectional force characteristics during the loading process, with the main forced direction being along the perfobond ribs, which is related to the stiffness ratio of the two directions. The two-way composite slabs have high bearing capacity and ductility, with obvious signs before failure. The specimens continue to bear the load after local punching failure of concrete near the loading point, which shows the features of both bending and punching failure. Based on the test results, a bending punching failure mode is proposed, which provides a new approach for the calculation of ultimate bearing capacity. An analytical calculation method for ultimate bearing capacity of orthotropic two-way composite slabs based on the failure mode above is derived with yield line theory and plastic theory, which is in excellent agreement with the tested results.

Effect of rotation and inclined load in a nonlocal magneto-thermoelastic solid with two temperature

Lata, Parveen,Singh, Sukhveer Techno-Press 2022 Advances in materials research Vol.11 No.1

This work deals with the two-dimensional deformation in a homogeneous isotropic nonlocal magneto-thermoelastic solid with two temperatures under the effects of inclined load at different inclinations. The mathematical model has been formulated by subjecting the bounding surface to a concentrated load. The Laplace and Fourier transform techniques have been used for obtaining the solution to the problem in transformed domain. The expressions for nonlocal thermal stresses, displacements and temperature are obtained in the physical domain using a numerical inversion technique. The effects of nonlocal parameter, rotation and inclined load in the physical domain are depicted and illustrated graphically. The results obtained in this paper can be useful for the people who are working in the field of nonlocal thermoelasticity, nonlocal material science, physicists and new material designers. It is found that there is a significant difference due to presence and absence of nonlocal parameter.

Flexural Durability and Chloride Diffusion Equation of TRC-Strengthened Beams under a Chloride Environment

Shiping Yin,Yuntao Hua,Yulin Yu 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.6

In this study, the chloride ion diffusion and structural performance of beams reinforced with textile-reinforced concrete (TRC) were evaluated. The parameters investigated were chloride concentration, sustained load and number of textile layers. The results demonstrate that the content and diffusion coefficient of chloride increased with increasing chloride concentration. Higher chloride concentrations accelerated the crack propagation and deflection changes and caused the reduction of the load-carrying capacity of the beams. The sustained load promoted the chloride transport of the TRC, increasing the chloride ion content and diffusion coefficient and causing substantial damage to the microstructure of the TRC. In addition, the performance (such as cracking resistance, deflection and flexural capacity) of beams with a large sustained load ratio decreased to a less extent than did the performance of the unloaded beams. The content and diffusion coefficient of chloride in the unstrengthened beams were obviously larger than those in the strengthened beams, but increasing the textile layers number had little influence on these factors. In addition, for the unstrengthened beams, the cracks and deflections developed rapidly, and the load decreased greatly, especially the cracking load. Finally, in accordance with Fick’s second law of diffusion, a chloride diffusion equation in TRC layers under new boundary conditions was proposed.

엔트로피 이론 기반의 유사농도 인자 산정

김영식,남윤창,전해성,전근학,추연문 한국산학기술학회 2020 한국산학기술학회논문지 Vol.21 No.10

Current methods of measuring the sediment concentration of natural streams can be affected by weather conditions and have lower reliability in bed-load sections due to mechanical limits. Theoretical methods have to be used to solve this problem, but they have low reliability compared to the measured values and diverse results for the bed-load sediment concentration. This study proposes a new way to reliably determine the bed-load sediment concentration from the relation with theoretical depth-integrated concentration based on the informational entropy concept. Sediment distribution shows a uniform probability distribution under maximized entropy conditions under some constraints, so a function can be calculated for the sediment distribution and depth-integrated concentration. The parameters of a stream were estimated by a nonlinear regression method using the concentration data from a past experiment. Equilibrium N (EN) was estimated using the relation between two different formulas proposed in this study, which can ease the estimation of both the total sediment distribution and depth-integrated sediment concentration with high reliable results with an average R2 of 0.924. 현재 자연 하천의 유사농도의 측정에 있어서 실제 측정은 기상 조건에 영향을 받으며, 기계적 한계로 인해 하천 바닥에 인접한 소류사 구간의 유사농도 측정값은 부유사 구간의 유사농도 측정값 보다 신뢰도가 낮다. 그리하여, 하천의 바닥농도는 이론식을 통해 산정되어왔으나, 기존 유사농도 계산 공식들의 바닥농도 산정값은 실측값에 비해 신뢰도가 낮고 서로 다른 공식 간의 차이는 여러 조건에 따라 천차만별이다. 따라서 하천의 바닥농도를 산정하기 위해 보다 신뢰성이 높은 공식이 요구되고 있다. 본 연구는 하천의 유사농도에 정보엔트로피이론을 적용하여 유사농도분포와 평균유사농도의 결정방법을 제시하고 평균유사농도와 바닥농도의 관계를 통해 바닥농도를 산정하는 방법을 제시하였다. 유사농도분포의 확률은 제약조건하에 계산된 최대 엔트로피에 의해 일정한 확률분포를 나타내게 되고, 이러한 관계에 근거하여 유사농도분포, 평균유사농도 그리고 바닥유사농도 간의 관계를 유도하고 측정 표본을 통해 바닥 유사농도를 산정할 수 있다. 본 연구의 이론 검증을 위해 과거 실험의 유사농도 측정값을 사용하여 유도된 유사농도분포와 평균유사농도 공식을 적용하였으며, 유도된 두 공식의 관계를 이용하여 대표 농도변수(EN : Equilibrium N )를 도출하였다. 대표 농도변수를 통해 산정한 점 농도는 실측값과 결정계수가 평균적으로 R2=0.924의 높은 신뢰도를 보였다. 이를 통하여, 실제 하천의 부유사 구간과 소류사 구간의 유사농도의 전체 경향을 보다 쉽게 파악하고 평균유사농도와 바닥농도의 관계를 이용하여, 신뢰도가 확보된 바닥농도를 손쉽게 산정할 수 있다.

온라인 교육에서 교수자 얼굴 포함 여부에 따른 학습자 인지부하, 집중력, 성취도의 차이 연구

김동심,류다현 한국컴퓨터교육학회 2023 컴퓨터교육학회 논문지 Vol.26 No.6

As online education spreads, research on effectively creating various types of online educational content is underway. There are differing opinions on the impact of content screen elements, such as including an instructor's face and gestures on the learning process and outcomes. Therefore, this study investigates whether including an instructor's face and gestures influences learners' cognitive load, concentration, and achievement. Using the prominent instructional design model ADDIE, lecture content was created with and without an instructor's face and gestures. An experiment was conducted with 56 university students without prior knowledge of ADDIE. After watching online educational content, the analysis of differences in learners' cognitive load, concentration, and achievement yielded the following results. Lecture content, including an instructor's face and gestures, showed a relatively low cognitive load. Specifically, significant differences were observed in the subfactor of cognitive load related to material design and overall cognitive load. However, there were no significant differences in concentration and achievement among groups based on including an instructor's face and gestures. Based on these findings, implications for instructional design strategies for online education content creation are proposed.

Partially encased composite columns using fiber reinforced concrete: experimental study

Margot F. Pereira,Silvana De Nardin,Ana L.H.C. El. Debs 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.6

This paper addresses the results of an experimental study involving 10 partially encased composite columns under concentric and eccentric compressive loads. Parameters such as slenderness ratio, ordinary reinforced concrete and fiber reinforced concrete, load eccentricity and bending axis were investigated. The specimens were tested to investigate the effects of replacing the ordinary reinforced concrete by fiber reinforced concrete on the load capacity and behavior of short and slender composite columns. Various characteristics such as load capacity, axial strains behavior, stiffness, strains on steel and concrete and failure mode are discussed. The main conclusions that may be drawn from all the test results is that the behavior and ultimate load are rather sensitive to the slenderness of the columns and to the eccentricity of loading, specially the bending axis. Experimental results also indicate that replacing the ordinary reinforced concrete by steel fiber reinforced concrete has no considerable effects on the load capacity and behavior of the short and slender columns and the proposed replacement presented very good results.

구멍이 있는 단이 진 비틀림 봉의 등가응력분포

강은혜,김영철,김명수,백태현 사단법인 인문사회과학기술융합학회 2017 예술인문사회융합멀티미디어논문지 Vol.7 No.3

Stress concentration is one of the causes of the damage due to the large stress than the mean stress acting on the bar. This paper presents the results for stress of a stepped bar with a hole under torsional loading. The analysis for stress concentration and shearing stress was done by ANSYS Workbench which is a commercial finite element analysis software. The analysis results on fillet and hole are increased as the distance between them are become close. In addition, the distribution of the maximum equivalent stress developed in the fillet and hole in the outside range of the specific distance L (-100 mm ~ 300 mm) was almost constant in the models used in the analysis. On the other hand, the distribution of the maximum equivalent stress developed in the fillet and hole in the inside range of the specific distance L (-100 mm ~ 300 mm) was rapidly increasing and decreasing the change in the models used in the analysis. In addition, it was also possible to identify the location where the differences between equivalent stresses of hole and fillet occurred within a specific distance L (-100 mm ~ 300 mm). The analysis results of paper can used when selecting a hole location in a stepped bar under torsional loading. 기하학적으로 급격히 변화되는 부분의 응력집중은 봉에 작용하는 평균응력 보다 큰 응력이 작용하여, 봉의 파손을 발생시키는 원인 중 하나이다. 구멍과 단이 있는 봉이 비틀림 하중을 받았을 경우, 응력집중 변화에 대해 구멍의 위치에 따른 관계를 규명하였다. 본 논문에서는 범용 유한요소 소프트웨어인 ANSYS Workbench를 통해 구멍의 위치가 다른 봉의 응력을 해석하였다. 해석된 결과, 필렛과 구멍이 서로 가까울수록 응력이 증가되는 것으로 나타났다. 또한, 본 해석에 사용된 모델에서는 구멍이 필렛으로부터 특정거리(L : -100 mm ~ 300 mm) 이상에서는 구멍과 필렛에서 발생한 최대 등가응력이 거의 일정하였다. 반면에, 구멍이 필렛으로부터 특정거리(L : -100 mm ~ 300 mm) 이하에서는 구멍과 필렛에서 발생한 최대 등가응력이 급격하게 증가 및 감소하는 변화를 보였다. 그리고 특정거리(L : -100 mm ~ 300 mm) 이하에서 구멍과 필렛에서 발생한 등가응력의 차이가 발생하는 지점을 확인할 수 있었다. 본 논문의 해석 결과는 비틀림을 받는 단이 있는 봉에서 구멍 위치를 선정할 때, 사용 될 수 있다.