• KIEAE Journal
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• 제10권5호
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• pp.151-157
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• 2010

This study is connected with evaluation of the progressive collapse resisting capacity for sustainable RC super tall building design. As the progressive collapse is not considered in current design codes in Korea, differences between linear static and dynamic analysis based on the GSA guidelines was analyzed for better evaluation, and the analysis model of flat plate system was determined. Finally, the progressive collapse resisting capacity was evaluated for structural system of super tall building. According to this study, the results by linear dynamic analysis were underestimated than the results by linear static analysis. Thus, the dynamic coefficient value of 2 provides conservative approach. The Effective Beam Width's model, currently used in field, is useful for the analysis about lateral force, but this model does not consider the effect of load redistribution by the slab. Hence, finite element analysis considering slab element will be needed for progressive collapse resisting capacity of the flat plate system. Finally, analysis model of 80-story building designed based on KBC(Korea Building Code) shows the weakness against progressive collapse because the DCR value is over 2. Thus, the countermeasure for alternative loading path such as installment of spandrel beam and reinforcements around slab is required to prevent the progressive collapse.

• 대한수의학회지
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• 제8권2호
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• pp.68-73
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• 1968

Four drugs, bithionol, hexachlorophee, hexachloroethane and tetrachloroethylene, were tested on the in vitro effects of vermicidal and laying capacity inhibitory action to the Eurytrema Pancreaticum of Korean cattle, and the results obtained were as follows : 1) Of the four drugs, bithionol was most effective at both high and low concentrations. 2) The effects of hexachlorophene, hexachloroethane and tetrachloroethylene were less effective than that of bithionol, and the laying activity, at low concentration, was observed to increase at the early stage and decrease gradually thereafter. 3) Tetrachloroethylene was least effective of the four drugs.

• Journal of Industrial and Engineering Chemistry
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• 제67권
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• pp.132-139
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• 2018

A cost-effective preparation method is proposed to prepare nanoporous alumina (NA) using aluminum chloride as a precursor with a lower cost than aluminum butoxide. In addition, the surfactant template was replaced with magnesium stearate, which has a lower unit cost in stearate acid. The adsorption isotherm test for the CO gas was carried out to compare the adsorption performance of the NA adsorbents prepared using post-hydrolysis (NA) and cost-effective precipitation (C-NA). In addition, C-NA exhibited a similar uptake capacity as NA, and the maximum uptake capacity of Pd/C-NA increased 1.3 times via Pd nanodots loading.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권10호
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• pp.3342-3360
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• 2014

In this paper, the capacity and BER performance of downlink distributed antenna systems (DAS) with transmit antenna selection and multiple receive antennas are investigated in MIMO composite channel, where path loss, Rayleigh fading and lognormal shadowing are all considered. Based on the performance analysis, using the probability density function (PDF) of the effective SNR and numerical integrations, tightly-approximate closed-form expressions of ergodic capacity and average BER of DAS are derived, respectively. These expressions have more accuracy than the existing expressions, and can match the simulation well. Besides, the outage capacity of DAS is also analyzed, and a tightly-approximate closed-form expression of outage capacity probability is derived. Moreover, a practical iterative algorithm based on Newton's method for finding the outage capacity is proposed. To avoid iterative calculation, another approximate closed-form outage capacity is also derived by utilizing the Gaussian distribution approximation. With these theoretical expressions, the downlink capacity and BER performance of DAS can be effectively evaluated. Simulation results show that the theoretical analysis is valid, and consistent with the corresponding simulation.

• Advances in concrete construction
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• 제10권4호
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• pp.289-299
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• 2020

A reliability analysis of the axial compressive load bearing capacity of postfire reinforced concrete (RC) columns strengthened with carbon fiber reinforced polymer (CFRP) sheets was presented. A 3D finite element (FE) model was built for heat transfer analysis using software ABAQUS. Based on the temperature distribution obtained from the FE analysis, the residual axial compressive load bearing capacity of RC columns was worked out using the section method. Formulas for calculating the residual axial compressive load bearing capacity of the columns after fire exposure and the axial compressive load bearing capacity of postfire columns retrofitted with CFRP sheets were developed. Then the Monte Carlo method was used to analyze the reliability of the axial compressive load bearing capacity of the RC columns retrofitted with CFRP sheets using a code developed in MATLAB. The effects of fire exposure time, load ratio, number of CFRP layers, concrete cover thickness, and longitudinal reinforcement ratio on the reliability of the axial compressive load bearing capacity of the columns after fire were investigated. The results show that within 60 minutes of fire exposure time, the reliability index of the RC columns after retrofitting with two layers of CFRPs can meet the requirements of Chinese code GB 50068 (GB 2001) for safety level II. This method is effective and accurate for the reliability analysis of the axial load bearing capacity of postfire reinforced concrete columns retrofitted with CFRP.

• 한국농공학회지
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• 제31권2호
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• pp.116-124
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• 1989

Based on the theory of runoff equation proposed by SCS, the actual storage capacity(Sa) as a modified retention paramater was introduced to estimate the effective rainfall for the daily streamfiow analysis. During a storm, the actual storage capacity is limited by either soil water storage or infiltration rate as precipitation increases. Therefore, it was assumed that Sa is dependent on the baseflow before storm runoff(Qb) corresponding to soil water storage and the total amount of precipitation(P) corresponding to infiltration rate of a watershed. Effective rainfalls (Direct run-offs) estimate4 from SCS equation using Sa were compared with observed effective rainfalls at 10 watersheds in Geum river watershed boundary. 1. Regression equation for Sa was supposed Sa=Co+C$_1$XP+C$_2$X Qb Regression coefficients were highly significant at the level of 0. 01 and R$^2$ were 0.57 to 0.73. 2. The adjustment of coefficient of initial abstraction was made according to the storm size. It was adjusted to 025 for 30mm or less, 0.23 for 30 to 80mm, 0.20 for 80 to 200mm, and 0.1 for 200mm or more. 3. Regression equations between estimated and observed effective rainfall showed that slopes were 0.857 to 1.029 and R$^2$ were 0.779 to 0.989,

• 한국ITS학회 논문지
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• 제21권1호
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• pp.35-50
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• 2022

중앙버스전용차로 설치 이후 버스의 통행우선권이 보장되어 버스 이용자들의 신뢰도가 향상되었지만 중앙버스정류장 용량 부족으로 정차 노선들의 통행속도와 정시성이 감소되는 등 정체현상이 발생하였다. 또한 중앙버스전용차로 및 중앙버스정류장 설치 시 기존시가지의 도로 기하구조를 바탕으로 설치하기 때문에 물리적인 제약이 따른다. 이에 본 연구는 중앙버스정류장 진출부의 신호 시스템 유효녹색시간을 최적화하여 운영 차원에서의 중앙버스정류장 용량 부족 문제의 개선 가능성을 제시하고자 하였다. 분석 방법론으로 TCQSM과 도로용량편람을 기초로 활용하였다. 물리적인 요인을 변수에서 제외할 수 있도록 구축 예정인 중앙버스정류장의 정차면수를 산정하였고 서울시의 현재 중앙버스전용차로가 설치되어 운영 중인 9개소의 중앙버스정류장을 임의로 선정 후 현장조사를 실시하여 분석자료로 활용하였다. 정류장 용량이 부족한 중앙버스정류장을 대상으로 정류장별 유효녹색시간 조정을 통해 시나리오 분석을 진행하였으며 종속변수는 중앙버스정류장의 용량으로 선정하였다. 분석 결과 운영 차원만의 개선 방안으로 용량이 부족한 중앙버스정류장 중 26.7%인 4개소의 정류장은 용량 부족 문제를 해결할 수 있는 것으로 도출되었다. 따라서 본 연구는 운영 차원의 개선 방안을 통하여 현재 운영 중인 중앙버스정류장의 용량 증대가 가능하다는 결과를 검증하였고 중앙버스정류장의 계획단계에서 공학적으로 산정된 중앙버스정류장의 정차면수를 확보할 수 없는 경우에도 효과가 있는 것으로 나타났다. 향후 중앙버스전용차로가 확대됨에 따라 중앙버스정류장 용량 문제가 더 많아질 것으로 예상되며 실질적인 중앙버스정류장의 개선 방안이 필요할 것으로 판단된다. 이에 따라 본 연구에서 제시한 결과는 물리적인 개선 방안을 도입하기 이전에 운영 차원 개선 방안의 기초자료로 활용되기를 기대한다.

• 한국안전학회지
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• 제21권2호
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• pp.70-79
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• 2006

many plumbing system are needed in the ceiling of the building as it becomes advanced more and more. This leads to make effective space between ceiling level and slab less. Also, piping system is not suitably arranged and operated if it is bent around the columns which they are a lot. But this system can be more effective if it passes through the columns directly. Most people think that those columns should not be damaged with such as holes. But actually this is existed in a hotel building in switzerland. This study is to fing out how much capacity the columns become damaged and low using model size of $20cm{\times}30cm$ rectangular section, and 160cm long, in the structural test. it's compressive strength is focused on $240kg/cm^{2}$ design strength, commonly used in korea. Compressive test for them was done at Hanyang University using UTM one thousand tone(1000t) capacity. Variable numbers for the study are one hole of dia 3cm with distance 20cm or 40cm, two holes of dia 3cm with 20cm and 40cm distance, one hole of dia 5cm with distance 20cm and 40cm, two holes of dia 5cm with 20cm and 40cm distance, me eccentric hole with 20cm and 40cm distance, Normal(without hole). two test specimens of each variable are made for the test. ED5H20 capacity was 16.7% decreased, compared to normal one. While ED5H40 distant 40cm from the end of column top showed 19.5% capacity decrease, compared to normal one. Strain of ED5H20 diameter 5cm, in distance of 20cm form the top of the column was less 5% than the one of diameter 3cm. Finally, conclusions are that in case of hole diameter 3cm, located at 20cm from the end of the column top, capacity was decreased down to 3, percent only compared to the same diameter hole with 20cm distant from the end of it.

• Geomechanics and Engineering
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• 제9권6호
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• pp.757-774
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• 2015

Reinforcing soils with the geosynthetics have been shown to be an effective method for improving the uplift capacity of granular soils. The pull-out resistance of the reinforcing elements is one of the most notable factors in increasing the uplift capacity. In this paper, a new reinforcing element including the elements (anchors) attached to the ordinary geogrid for increasing the pull-out resistance of the reinforcement, is used. Thus, the reinforcement consists of the geogrid and anchors with the cylindrical plastic elements attached to it, namely grid-anchors. A three-dimensional numerical study, employing the commercial finite difference software FLAC-3D, was performed to investigate the uplift capacity of the pipelines buried in sand reinforced with this system. The models were used to investigate the effect of the pipe diameter, burial depth, soil density, number of the reinforcement layers, width of the reinforcement layer, and the stiffness of geogrid and anchors on the uplift resistance of the sandy soils. The outcomes reveal that, due to a developed longer failure surface, inclusion of grid-anchor system in a soil deposit outstandingly increases the uplift capacity. Compared to the multilayer reinforcement, the single layer reinforcement was more effective in enhancing the uplift capacity. Moreover, the efficiency of the reinforcement layer inclusion for uplift resistance in loose sand is higher than dense sand. Besides, the efficiency of reinforcement layer inclusion for uplift resistance in lower embedment ratios is higher. In addition, by increasing the pipe diameter, the efficiency of the reinforcement layer inclusion will be lower. Results demonstrate that, for the pipes with an outer diameter of 50 mm, the grid-anchor system of reinforcing can increase the uplift capacity 2.18 times greater than that for an ordinary geogrid and 3.20 times greater than that for non-reinforced sand.

• Geomechanics and Engineering
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• 제8권4호
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• pp.595-613
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• 2015

An experimental investigation into the uplift capacity of horizontal square plate anchors in sand with and without geogrid reinforcement is reported. The parameters investigated are the effect of the depth of the single layer of geogrid, vertical spacing of geogrid layers, number of geogrid layers, length of geogrid layers, the effects of embedment depth, and relative density of sand. A series of three dimensional finite element analyses model was established and confirmed to be effective in capturing the behaviour of plate anchor-reinforced sand by comparing its predictions with experimental results. The results showed that the geogrid reinforcement had a considerable effect on the uplift capacity of horizontal square plate anchors in sand. The improvement in uplift capacity was found to be strongly dependent on the embedment depth and relative density of sand. A satisfactory agreement between the experimental and numerical results on general trend of behaviour and optimum geometry of reinforcement placement is observed. Based on the model test results and the finite element analyses, optimum values of the geogrid parameters for maximum reinforcing effect are discussed and suggested.