• Earthquakes and Structures
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• 제25권3호
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• pp.149-160
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• 2023

Over the course of the last 4-5 years, India's northeastern region have widely used Autoclaved Aerated Concrete (AAC) blocks to construct load-bearing masonry structures. The aim of this investigation is to examine the shear characteristics of AAC masonry triplet assemblage strengthened by using two techniques, i.e., the bead joint (BJ) and the bed-head joint (BHJ) technique. Three unique variations of wire mesh were involved in the strengthening method. Furthermore, three strengthening configurations were used to strengthen each of the three wire mesh variations and the two-strengthening method, i.e. (-), L and (Z) configuration. The unreinforced and reinforced triplet masonry wallets were tested under direct shear test. From the results obtained, the 'BJ'triplet masonry wallets observed an enhanced in shear strength of about 2.23% to 23.33 % whereas the 'BHJ' triplet masonry wallets observed an enhanced in shear strength of about 22.92% to 50.69%. The "BHJ" strengthening method effectively enhance the shear strength of the triplet masonry wallets compared to the "BJ" and the "UR" wallets with an increase in capacity as the wire mesh strength increases. Furthermore, in terms of the strengthening configuration, the (Z) configuration performs better, followed by the (L) and (-) configuration demonstrating the strengthening configuration effectiveness.

• Geomechanics and Engineering
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• 제36권2호
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• pp.121-130
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• 2024

Many foundation projects are built on red-bed soft rocks, and the damage evolution of this kind of rocks affects the safety of these projects. At present, there is insufficient research on the damage evolution of red-bed soft rocks, especially the progressive process from mesoscopic texture change to macroscopic elastoplastic deformation. Therefore, based on the dual-porosity characteristics of pores and fissures in soft rock, we adopted a cellular automata model to simulate the propagation of these voids in soft rocks under an external load. Further, we established a macro-mesoscopic damage model of red-bed soft rocks, and its reliability was verified by tests. The results indicate that the relationship between the number and voids size conformed to a quartic polynomial, whereas the relationship between the damage variable and damage porosity conformed to a logistic curve. The damage porosity was affected by dual-porosity parameters such as the fractal dimension of pores and fissures. We verified the reliability of the model by comparing the test results with an established damage model. Our research results described the progressive process from mesoscopic texture change to macroscopic elastoplastic deformation and provided a theoretical basis for the damage evolution of these rocks.

• 한국산학기술학회논문지
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• 제21권10호
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• pp.325-333
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• 2020

현재 자연 하천의 유사농도의 측정에 있어서 실제 측정은 기상 조건에 영향을 받으며, 기계적 한계로 인해 하천바닥에 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. 유사농도 분포의 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.

• 생물환경조절학회지
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• 제2권2호
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• pp.99-109
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• 1993

Cooling of nutrient solution is essential to improve the growth environment of crops in hydroponic culture during summer season in Korea. This study was carried out to provide fundamental data for development of the cooling system satisfying the required cooling load of nutrient solution in hydroponic greenhouse. A numerical model for prediction of the cooling load of nutrient solution in hydroponic greenhouse was developed, and the results by the model showed good agreements with those by experiments. Main factors effecting on cooling load were solar radiation and air temperature in weather data, and conductivity of planting board and area ratio of bed to floor in greenhouse parameters. Using the model developed, the design cooling load of nutrient solution in hydroponic greenhouse of 1,000$m^2$(300pyong) was predicted to be 95,000 kJ/hr in Suwon and the vicinity.

• Journal of Forest and Environmental Science
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• 제6권1호
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• pp.8-17
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• 1989

Recent development of industry and urbanization in the interior of mountainous area increases the possibility of occurence of natural disaster, such as flood, landslide and deblis-flow. Erosion control facilities, which were the most significant activity to riverbed fixiation, were constructed at the downstream of the experimental basin. In the mountain torrents, the complex bed load transport has occurred by the drift of running water, and resulting in a formation of terrace deposits. Especially, channel migration caused by scouring and deposition frequently occurs at the wide areas of the river bed. Consequently, the unsymmetrical river bed charactristics indicate the degree of the channel migration.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 추계 학술논문 발표대회
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• pp.200-201
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• 2015

The unit modular method is one in which unit modules are prefabricated at a factory and then constructed at a construction site. That is why an important process, transporting unit module, is added in this method. The purpose of this study is to analyse the load for transporting unit module. The results of the analysis of the driving experimental runs revealed that a maximum load of 15 kN was applied on adapter block type A and a maximum load of 25 kN on adapter block type B. These loads were recorded at the points in the road test when the low-bed trailer was driving through unstable sections of the test such as stopping, restarting, passing over a speed bump or taking a left turn at speed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권6호
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• pp.2035-2049
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• 2015

Applications deployed in cloud receive a huge volume of requests from geographically distributed users whose satisfaction with the cloud service is directly proportional to the efficiency with which the requests are handled. Assignment of user requests based on appropriate load balancing principles significantly improves the performance of such cloud-based applications. To study the behavior of such systems, there is a need for simulation tools that will help the designer to set a test bed and evaluate the performance of the system by experimenting with different load balancing principles. In this paper, a novel architecture for cloud called Request Assignment Simulator (RAS) is proposed. It is a customizable, visual tool that simulates the request assignment process based on load balancing principles with a set of parameters that impact resource utilization. This simulator will help to ascertain the best possible resource allocation technique by facilitating the designer to apply and test different load balancing principles for a given scenario.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1497-1502
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• 2011

Increasing tensions of contact wire and messenger wire are essential to construct a test-bed for catenary system in the 400km/h speed on Honam high-speed railway. Because heavy load is applied to a mast due to the increased the tensions of both wires it is required to investigate the strength of the foundation. Therefore, in this study the maximum moment of an electric pole under the worst condition was calculated to investigate the strength of the pole foundation on the bridges. The maximum moment database table used in the construction of Kyungbu high-speed railway was referenced to derive the worst conditions and to review the composition of catenary system in the test-bed section. From the results of this study regarding assumptions and calculation process it will be possible to estimate the optimized strength of the pole foundations on the bridges which will be constructed in the future.

• Environmental Engineering Research
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• 제16권4호
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• pp.231-236
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• 2011

Biological nitrogen removal, using a continuous flow packed-bed reactor (CPBR) in a consecutive nitrification and denitrification process, was evaluated. An apparent decline in the nitrification efficiency coincided with the steady increase in $NH_4{^+}$-N load. Sustained nitrification efficiency was found to be higher at longer empty bed contact times (EBCTs). The relationship between the rate of alkalinity consumption and $NH_4{^+}$-N utilization ratio followed zero-order reaction kinetics. The heterotrophic denitrification rate at a carbon-tonitrogen (C/N) ratio of >4 was found to be >74%. This rate was higher by a factor of 8.5 or 8.9 for $NO_3{^-}$-N/volatile solids (VS)/day or $NO_3{^-}-N/m^3$ ceramic media/day, respectively, relative to the rates measured at a C/N ratio of 1.1. Autotrophic denitrification efficiencies were 80-90%. It corresponds to an average denitrification rate of 0.96 kg $NO_3{^-}-N/m^3$ ceramic media/day and a relevant average denitrification rate of 0.28 g $NO_3{^-}$-N/g VS/day, were also obtained. Results presented here also constitute the usability of an innovative porous sulfur ceramic media. This enhanced the dissolution rate of elemental sulfur via a higher contact surface area.

• Journal of Biosystems Engineering
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• 제37권3호
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• pp.155-165
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• 2012

This study was performed to offer the data for design of the seedling bed transfer equipment to make the automation of working process in a plant factory. The seedling bed transfer equipment pushing the seedling bed with bearing wheels on the rail for interconnecting each working process by a pneumatic cylinder was made and examined. The examined transfer force to push the seedling bed with a weight of 178.9 N by the pneumatic cylinder with length of 60 cm and section area of 5 $cm^2$ was measured by experiments. The examined transfer forces was compared with theoretical ones calculated by the theoretical formula derived from dynamic system analysis according to the number of the seedling bed and pushing speed of the pneumatic cylinder head at no load. The transfer function of the equipment with the input variable as the pushing speed $V_{h0}$(m/s) and the output variable as the transfer force f(t)(N) was represented as $F(s)=(V_{h0}/k)(s+B/M)/(s(s^2+Bs/M+1/(kM))$ where M(kg), k(m/N) and B(Ns/m) are the mass of the bed, the compression coefficient of the pneumatic cylinder and the dynamic friction coefficient between the seedling bed and the rail, respectively. The examined transfer force curves and the theoretical ones were represented similar wave forms as to use the theoretical formular to design the device for the seedling bed transfer. The condition of no vibration of the transfer force curve was $kB^2>4M$. The condition of transferring the bed by the repeatable impact and vibration force according to difference of transfer distance of the pneumatic cylinder head from that of the bed was as $Ce^{-\frac{3{\pi}D}{2\omega}}<-1$, where ${\omega}=\sqrt{\frac{1}{kM}-\frac{B^2}{4M^2}}$, $C=\{\frac{\frac{B}{2M}-\frac{1}{kB}}{\omega}\}$, $D=\frac{B}{2M}$. The examined mean peak transfer force represented 4 times of the stead state transfer force. Therefore it seemed that the transfer force of the pneumatic cylinder required for design of the push device was 4Bv where v is the pushing speed.