• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.203-206
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• 2005

Reinforced concrete(RC) column-bent piers represent one of the popular piers used in highway bridges of Korea. Seismic performance of RC column-bent piers under bi-directional seismic loadings was experimentally investigated. Six column bent piers were constructed with two circular supporting columns which were made in 400 mm diameter and 2,000 mm height. Test parameters are different transverse reinforcement ratio and loading pattern. Three specimens were loaded with bi-directional lateral forces which were main cyclic loads in the longitudinal direction and sub-cyclic loads in the transverse direction. Other three specimens were loaded in the opposite way. Test results indicated that lateral strength and ductility of the latter specimens were bigger than those of the former specimens. Plastic hinge was formed with the spall of cover concrete and the fracture of the longitudinal reinforcing steels in the bottom part of two supporting columns for the former three specimens. Similar behavior was observed in the top and bottom parts of two supporting columns for the latter three specimens.

• Geomechanics and Engineering
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• 제6권2호
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• pp.195-211
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• 2014

Stone columns (or granular column) have been used to increase the load carrying capacity and accelerating consolidation of soft soil. Recently, the geosynthetic reinforced stone column technique has been developed to improve the load carrying capacity of the stone column. In addition, reinforcement prevents the lateral squeezing of stone in to surrounding soft soil, helps in easy formation of stone column, preserve frictional properties of aggregate and drainage function of the stone column. This paper investigates the improvement of load carrying capacity of isolated ordinary and geotextile reinforced sand column through field load tests. Tests were performed with different reinforcement stiffness, diameter of sand column and reinforcement length. The results of field load test indicated an improved load carrying capacity of geotextile reinforced sand column over ordinary sand column. The increase in load carrying capacity depends upon the sand column diameter, stiffness of reinforcement and reinforcement length. Also, the partial reinforcement length about two to four time's sand column diameter from the top of the column was found to significant effect on the performance of sand column.

• 한국BIM학회 논문집
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• 제3권3호
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• pp.19-28
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• 2013

In Korea highway bridges, most piers are the type of one-column or multi-column ones. So, in this study, under an environment applying BIM so fast, to activate researches on two-column piers subjected to bidirectional seismic loading, a 3D parametric modeling method was selected when the model of two-column piers and one-column piers were formed. Also, interface module between input data in structural analysis and 3D model of RC pier was developed. The module can create the input data for non-linear structural analysis like material, geometric properties and additional coefficients.

• Journal of Microbiology and Biotechnology
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• 제26권7호
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• pp.1285-1289
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• 2016

A split-column photobioreactor (SC-PBR), consisting of two bubble columns with different sizes, was developed to enhance the photon utilization efficiency in an astaxanthin production process from Haematococcus lacustris. Among the two columns, only the smaller column of SC-PBR was illuminated. Astaxanthin productivities and photon efficiencies of the SC-PBRs were compared with a standard bubble-column PBR (BC-PBR). Astaxanthin productivity of SC-PBR was improved by 28%, and the photon utilization efficiencies were 28-366% higher than the original BC-PBR. The results clearly show that the effective light regime of SC-PBR could enhance the production of astaxanthin.

• Archives of Pharmacal Research
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• 제21권2호
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• pp.212-216
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• 1998

A coupled achiral-chiral high-performance liquid chromatographic system has been developed for the determination of the enantiomers of salmeterol, S-(+)-salmeterol and R-(-)-salmeterol in urine. THe salmeterol was separated from the interfering components in urine and quantified on the silica column, and the enantiomeric composition was determined on a Sumichiral OA-4700 chiral stationary phase. The two columns were connected by a switching valve equipped with a silica precolumn. The two columns wer connected by a switching valve equipped with a silica precolumn. The precolumn was used to concentrate the salmeterol in the eluent from the achiral column before backflushing onto the chiral phase. The coupled system was validated.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권5호
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• pp.332-339
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• 2000

Experimental and theoretical works were performed for the separation of large polyelectrolytes such as DNA in the column packed with gel particles under an electric field. This paper shows how intraparticle convection effects the separation of DNAs in the column because DNAs quickly oriented through the pores in the field direction. Dimensionless transient mass balance equations were derived considering diffusion and electrophoretic convection. The separation criteria is theoretically studied using two different Peclet numbers in the fluid and solid phases and these criteria were verified uing two different DNAs by electrophoretic mobilities measured experimentally, showing how the separation position of DNAs varies in the column according to values of Pe(sub)f/Pe(sub)g of individual DNA. Governing equations are simultaneously solved by operator theoretic and characteristic methods to yield the column response.

• 설비공학논문집
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• 제12권8호
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• pp.735-744
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• 2000

In order to define the heat transfer characteristics in a spray column direct contact heat exchanger, the development of a multidimensional numerical model and computational algorithm is essential to analyze the inherent multidimensional characteristics of a direct contact heat exchanger. In the present study, it has been carried out numerical calculations using a two-dimensional model for operation of a direct contact heat exchanger. Such operational and system parameters as the injection velocity, void fraction, aspect ratio and injection temperature of each fluid are examined thoroughly to assess their influence on the performance of a spray column. Analyzed results has shown that our two-dimensional model predicts the heat transfer phenomena well in a spray column.

• Earthquakes and Structures
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• 제14권3호
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• pp.273-283
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• 2018

Previous experimental researches indicate that reinforced concrete beam-column joints play an important role in the mechanical properties of moment resisting frame structures, so as to require proper design. In order to get better understanding of the beam-column joint performance, a rational model needs to be developed. Based on the former considerations, two typical models for calculating the shear carrying capacity of the beam-column joint including the inelastic reinforced concrete joint model and the softened strut-and-tie model are selected to be introduced and analyzed. After examining the applicability of two typical models mentioned earlier to interior beam-column joints, several adjustments are made to get better predicting of the test results. For the softened strut-and-tie model, four adjustments including modifications of the depth of the diagonal strut, the inclination angle of diagonal compression strut, the smeared stress of mild steel bars embedded in concrete, as well as the softening coefficient are made. While two adjustments for the inelastic reinforced concrete joint model including modifications of the confinement effect due to the column axial load and the correction coefficient for high concrete are made. It has been proved by test data that predicted results by the improved softened strut-and-tie model or the modified inelastic reinforced concrete joint model are consistent with the test data and conservative. Based on the test results, it is also not difficult to find that the improved beam-column joint model can be used to predict the joint carrying capacity and cracks development with sufficient accuracy.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.742-748
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• 1993

The dynamics and control of two complex column configurations (sidestream column with stripper; prcfractionater/sidestream column configuration), which are multivariable interacting and nonlinear, have been studied. A new control scheme developed by Hanand Park(1993) to deal with the nonlinear and multivariable nature of distillation processes has been applied to these complex distillation configurations. The control scheme incorporates a nonlinear wave model into a generic model control framework. An observer based on the nonlinear wave model is used to determine the profile positions of distillation column sections. The control scheme enables tight control of the profile position of each column section that leads to fast stabilization of product compositions.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 추계 학술발표회
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• pp.291-311
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• 2006

The acceleration of consolidation by stone columns was mostly analysed within the framework of a basic unit cell model (i.e. a cylindrical soil body around a column). A method of converting the axisymmetric unit cell into the equivalent plane-strain model would be required for two-dimensional numerical modelling of multi-column field applications. This paper proposes two practical simplified conversion methods to obtain the equivalent plane-strain model of the unit cell, and investigates their applicability to multi-column reinforced ground. In the first conversion method, the soil permeability is matched according to an analytical equation, whereas in the second method, the column width is matched based on the equivalence of column area. The validity of these methods is tested by comparison with the numerical results of unit-cell simulations and with the field data from an embankment case history. The results show that for the case of linear-elastic material modelling, both methods produce reasonably accurate long-term consolidation settlements, whereas for the case of elasto-plastic material modelling, the second method is preferable as the first one gives erroneously lower long-term settlements, where plastic yielding of stone column are ignored.