• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2000년도 추계학술대회
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• pp.96-98
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• 2000

Column experiments were peformed to evaluate the efficiency of surfactant flushing for remediation of non-aqueous phase liquid (NAPL) in the soil under controlled conditions. In column experiment less than 0.1 % of the original mass of tetrachloroethylene (PCE), remained in the column after 15 pore volumes of 1% sorbitan monooleate solution were passed through columns. To determine the influence of soil parameters that may affect the remediation process, column tests were repeated with different values of grain size, application rate, surfactant type, surfactant concentration, and solution viscosity (polymer mixed with surfactant). Experimental works suggest that surfactant flushing has a great potential to rapidly remove mass from NAPL in the soil.

• 한국식품영양학회지
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• 제4권2호
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• pp.141-148
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• 1991

In order to Investigate the extraction mechanism of barley tea in cylindrical packed column, pilot plant scale packed column was designed and constructed. And extraction conditions for steady flow in the packed column were searched. The main results of this study are as follows ; 1. Circulation of the stock barley tea before the extraction running was indispensable In consideration of inequality, gas, particles existed in packed bed. Solid-liquid equilibrium was initially maintained after the circulation. 2. Flow direction of solvent must be up-flow for maintaining the constant bed height and flow rate during the extraction. Paessure drop in pucked bed was similar to decrease ratio of extract concentration. 3. The porosity of packed bed was in the range of 0.24∼0.36 according to the particle sloe. And it was decreased as the particle size became smaller.

• Steel and Composite Structures
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• 제12권2호
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• pp.93-115
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• 2012

This paper presents a numerical investigation of the mechanical behaviour of extended end - plate steel connections including comparison with full size experiments. Contact and friction laws have been taken into account with nonlinear, three dimensional finite element analysis. Material and geometric nonlinearities have been implemented to the model, as well. Results are then compared with experimental tests conducted at the Jordan University of Science and Technology. According to the most significant observation of the analysis, a separation of the column flange from the extended end - plate occurs. Other important structural parameters of the connection, like the impact of some column stiffeners on the overall response, local buckling of the column and friction of the beam to column interface, have been examined as well.

• Advances in concrete construction
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• 제8권2호
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• pp.91-100
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• 2019

In this paper three damaged exterior RC beam-column joints made of recycled aggregate concrete (RAC) were repaired. The aim of the study was to restore back the lost capacity of the beam-column joint to the original state or more. A relatively cheap material locally available galvanized steel welded wire mesh (GSWWM) of grid size 25 mm was used to confine the damaged region and then jacketed with cement mortar. Repaired specimens were also subjected to similar cyclic displacement as those of unrepaired specimens. Seismic parameters such as load carrying capacity, ductility, energy dissipation, stiffness degradation etc. were analyzed. Results show that repaired specimens exhibited better seismic performance and hence the adopted repairing strategies could be considered as satisfactory. These findings would be helpful to the field engineers to adopt a suitable rapid and cost efficient repairing technique for restoring the damaged frame structural joints for post earthquake usage.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.41-42
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• 2022

This study analyzed the process related to the linkage between on-site work targeting the middle size Precast Concrete(PC) public apartment building with beam-column system and prepared on-site works flow relationship diagram in which the wet process consists of core Critical Path(CP) to prepare a network diagram of the Precedence Diagram Method(PDM). Through this study, it is expected that it will be possible to maximize the project management capability by suggesting a method to minimize risk factors and the optimized process management of the beam-column system PC public apartment building.

• 한국농공학회논문집
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• 제51권5호
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• pp.1-8
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• 2009

Photobioreactor (PBR) that houses and cultivates microalgae providing a suitable environment for its growth, such as light, nutrients, CO2, heat, etc. is now getting more popular in the last decade. Among the many types of PBRs, the bubble column type is very attractive because of its simple construction and easy operation. However, despite the availability of these PBRs, only a few of them can be practically used for mass production. Many limitations still holdback their use especially during their scale-up. To enlarge the culture volume and productivity while supplying optimum environmental conditions, various PBR structures and process control are needed to be investigated. In this study, computational fluid dynamics (CFD) was economically used to design a bubble-column type PBR taking the place of field experiments. CFD is a promising technique which can simulate the growth and production of microalgae in the PBR. To study bubble column PBR with CFD, the most important factor is the possibility of realizing bubble. In this study, multi-phase models which are generally used to realize bubbles were compared by theoretical approaches and comparing in a 2D simulation. As a result, the VOF (volume of fluid) model was found to be the most effective model to realize the bubbles shape as well as the flow inside PBR which may be induced by bubble injection. Considering the accuracy and economical efficiency, 0.005 second time step size was chosen for 2.5 mm mesh size. These results will be used as criteria for scale-up in the PBR simulation.

• 한국해양환경ㆍ에너지학회지
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• 제2권1호
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• pp.26-33
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• 1999

오염된 지역의 연안 퇴적물은 PCB 등 소수성 오염 물질을 흡착하고 있으며, 준설과 같은 환경 정화사업을 할 때, 재부유되어 오염되지 않은 인근 수역으로 이동될 수 있다. 이러한 환경 영향의 평가를 위해 저자는 앞서 침강, 연직확산, 응집에 의해 입자크기 분포가 변화하는 것을 모사할 수 있는 수학적 모델을 개발 제시한 바 있다. 본 연구에서는 이 모델을 이용하여, 연안환경을 실험적으로 재현한 높이 2 m의 settling column으로부터 측정된 입자크기분포 자료를 이용하여 시뮬레이션하며 분석한 결과를 제시하였다. 분석결과, 모델은 퇴적물 입자가 column 내에서 연직이동을 하며 입자 분포가 시간적으로 또 수심별로 변화하는 것을 상당히 잘 예측하는 것으로 나타났으며 재부유된 퇴적물 입자는 연직이동과 함께 응집이 되고 있는 것으로 분석되었다. 따라서 본 연구는 크기가 다양한 오염된 퇴적물이 응집에 의해 입자크기분포가 변화하며 연직 이동되는 매우 복잡한 현상에 대해 유효하게 컴퓨터 모사할 수 있음을 보였다.

• Earthquakes and Structures
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• 제7권6호
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• pp.1001-1024
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• 2014

The size of spread footings was found to be unnecessarily large from some actual engineering practices constructed in Taiwan, due to the strict design provisions related to footing uplift. According to the earlier design code in Taiwan, the footing uplift involving separation of footing from subsoil was permitted to be only up to one-half of the foundation base area, as the applied moment reaches the value of plastic moment capacity of the column. The reason for this provision was that rocking of spread footings was not a favorable mechanism. However, recent research has indicated that rocking itself may not be detrimental to seismic performance and, in fact, may act as a form of seismic isolation mechanism. In order to clarify the effects of the relative strength between column and foundation on the rocking behavior of a column, six circular reinforced concrete (RC) columns were designed and constructed and a series of rocking experiments were performed. During the tests, columns rested on a rubber pad to allow rocking to take place. Experimental variables included the dimensions of the footings, the strength and ductility capacity of the columns and the intensity of the applied earthquake. Experimental data for the six circular RC columns subjected to quasi-static and pseudo-dynamic loading are presented. Results of each cyclic loading test are compared against the benchmark test with fixed-base conditions. By comparing the experimental responses of the specimens with different design details, a key parameter of rocking behavior related to footing size and column strength is identified. For a properly designed column with the parameter higher than 1, the beneficial effects of rocking in reducing ductility and the strength demand of columns is verified.

• 센서학회지
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• 제26권2호
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• pp.85-90
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• 2017

A wide dynamic range (WDR) CMOS image sensor (CIS) was developed with a specialized readout architecture for realizing high-sensitivity (HS) and low-sensitivity (LS) reading modes. The proposed pixel is basically a three-transistor (3T) active pixel sensor (APS) structure with an additional transistor. In the developed WDR CIS, only one mode between the HS mode for relatively weak light intensity and the LS mode for the strong light intensity is activated by an external controlling signal, and then the selected signal is read through each column-parallel readout circuit. The LS mode is implemented with the column capacitors and a feedback structure for adjusting column capacitor size. In particular, the feedback circuit makes it possible to change the column node capacitance automatically by using the incident light intensity. As a result, the proposed CIS achieved a wide dynamic range of 94 dB by synthesizing output signals from both modes. The prototype CIS is implemented with $0.18-{\mu}m$ 1-poly 6-metal (1P6M) standard CMOS technology, and the number of effective pixels is 176 (H) ${\times}$ 144 (V).

• 한국강구조학회 논문집
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• 제12권4호통권47호
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• pp.429-436
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• 2000

철골 보와 철근콘크리트 기둥으로 구성된 복합 시스템은 철골과 철근콘크리트 간에 재료적인 단점을 보완함으로써 구조 효율성과 시공 생산성을 높이는 이점을 가지고 있다. 이 연구는 철골 보에 현장 타설 철근콘크리트 기둥을 간편하게 접합시킬 수 있는 복합구조 시스템을 개발하고, 그 시스템의 휨 및 전단 저항성능을 시험을 통하여 규명하는 것을 목적으로 하고 있다.