• Korean Chemical Engineering Research
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• v.51 no.1
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• pp.93-97
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• 2013

A lab-sized distillation experiment was conducted using small-size packings and a horizontal distillation column. The 6.7 mm Raschig ring type packings of stainless steel and a 40 mm glass column were used, and five independent electric heaters were installed in the axial direction to adjust the column inside temperature separately. The temperature was continuously distributed along the column length to provide equivalent equilibrium to the temperature for the separation. From the experimental results, a larger HETP of the column than the vertical distillation column was obtained, but it was found that the practical separation with proper processing capacity and separation efficiency was available.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.2
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• pp.157-162
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• 2015

A large five-axis gantry-type machine performs cutting operations by moving the gantry, along with a bed. During operation, there are three sources of position (zig-zag) errors: 1) the position difference between two control motors on the X axis, 2) friction difference from the different column weights, and 3) torque of the rotating spindle. This study improved the performance of a gantry-type machine by analyzing these three error sources. We changed the mass of a column in the gantry structure and measured the effect on the friction result. We also studied the spindle torque influences on the movement performance of the gantry in relation to the spindle rotation.

• Journal of Korean Association for Spatial Structures
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• v.8 no.1
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• pp.89-97
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• 2008

The object of this paper is to evaluate on behavior the experimentally of beam-to-column joints for modular steel frame with the hollow structural steel section to LEB C-shape. Beam-to-column joints carried out test on the joint shape bracket-type and welded-type to consideration which the joints for modular steel frame was capacity, deformation and failure mode. Test of results, the beam-column joints decided to the lateral buckling strength in LEB C-shape regardless of joint-shape and joint failure. The strength & stiffness for joints increase as the bracket-thickness. The results from theory of lateral buckling are compared to the experimental results. The ratio of experimental results to theory value is $0.83{\sim}0.95$ in the case of bracket-type and welded-type of $0.87{\sim}0.9$, indicating an accurate and safe estimation.

• Journal of KIBIM
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• v.3 no.3
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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.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.29-32
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• 2009

Building foundations for Top-Down construction require a special setting, because the foundations have to be placed way before excavation for the substructure of main building, Usually, the foundation goes into the layer of rock and it is often called rock-pier foundation, Currently, a cage of steel reinforcing bars is inserted to the pre-excavated hole in the rock layer, hanging down from the wide flange steel column above. This paper presents a new method for connecting the prefounded column and the steel cage with a coupler for better connection between the two, The use of a circular Concrete Filled Tube (CFT) as a prefounded column makes it possible to have this type of connection. The details of the connection and application to a Top-Down construction site is also included in this paper.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.4B
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• pp.253-259
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• 2012

Wastewater-adapted microalgae such as Chlorella vulgaris AG10032, Ankistrodesmus gracilis SAG278-2 and Scenedesmus quadricauda AG10308 are useful biological resources for recovering biofuel and other bio-based materials from wastewater because of their efficient removals of nitrogen and phosphorus from wastewater and their high fatty acid contents in biomass. Although the concentrations of phosphorus typically vary in wastewater environment, very little is known about the effect of phosphorus concentration, especially phosphorus starvation, on microalgal fatty acid synthesis. This is partially due to the lack of methodological establishment for algal fatty acid analysis. In this study, we compared the analysis performances of microalgal fatty acids by two different methods; one is a non-polar GC (gas chromatography) column based method, which is generally used for microbial fatty acids, and the other is a polar WAX-type GC column method, which is typically used for plant fatty acids. And then, we explored the effect of phosphorus concentration levels on fatty acid production in microalgae cultivated from wastewater. As results, the polar WAX-type column method has better ability to separate poly unsaturated fatty acids (PUFA) including $C_{18:3}$ (linolenic acid), and was found to be more applicable in analyzing fatty acids from wastewater-cultivated microalgae than the non-polar column method. The fatty acid characterization by the WAX-type column method revealed little effect of phosphorus starvation on the quantity and composition of fatty acids from wastewater-cultivated microalgae.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.8
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• pp.850-856
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• 2009

A new type bi-directional damper using a tuned liquid column damper(TLCD) and a tuned sloshing damper(TSD) is introduced in this study. Two dampers are usually needed to reduce wind-induced responses of tall buildings since they are along and across wind ones. The proposed damper has the advantage of controlling both responses with one damper. One of objectives of this study is to derive analytical dynamics to investigate coupled effects due to TLCD and TSD. Another objective is to address the effect of coupled control force due to TLCD and TSD on the dynamic characteristic of the damper based on analytical dynamics. Shaking table test is undertaken to experimentally grasp dynamic characteristics of the damper under white noise excitation. Its dynamic characteristic is expressed by the transfer function from the shaking table acceleration to the control force generated from the damper. Finally, its design parameters are identified based on the coupled dynamics, which include the mass ratio of horizontal liquid column to total liquid for a TLCD, the participation factor of the fundamental liquid sloshing for a TSD and damping ratio for both cases.

• Steel and Composite Structures
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• v.25 no.4
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• pp.443-456
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• 2017

Many authors have established the usefulness of concrete filled steel tubular (CFST) sections as compression members while few have proved their utility as flexural members. To explore their prospective as part of CFST frame structures, two types of connections using extended end plate and seat angle are proposed for exterior joints of CFST beams and CFST columns. To investigate the performance and failure modes of the proposed bolted connections subjected to static loads, an experimental program has been executed involving ten specimens of exterior beam-to-column joints subjected to monotonically increasing load applied at the tip of beam, the performance is appraised in terms of load deformation behaviour of joints. The test parameters varied are the beam section type, type and diameter of bolts. To validate the experimental behaviour of the proposed connections in CFST beam-column joints, finite element analysis for the applied load has been performed using software ATENA-3D and the results of the proposed models are compared with experimental results. The experimental results obtained agree that the proposed CFST beam-column connections perform in a semi-rigid and partial strength mode as per specification of EC3.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.5
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• pp.403-410
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• 2009

In this paper, damping coefficients and effective masses of tuned liquid-type column dampers were quantitatively evaluated based on experimental results by using system identification technique. First, shaking table tests were performed for two types of tuned liquid-type column dampers. Then, the dynamic characteristics of dampers used in this study were experimentally grasped from harmonic wave excitation testing results of the dampers with various water level. Finally, damping ratios and effective masses of the dampers with varying water level were quantitatively evaluated from minimizing the errors between numerical and experimental results. It was confirmed from system identification results that damping ratio and effective mass are decreased as the water level of dampers is increased.

• Steel and Composite Structures
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• v.32 no.4
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• pp.497-507
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• 2019

Exposed column base connections are used in low- to mid-rise steel moment resisting frames. This paper is to investigate the effect of the base plate thickness on the exposed column base connection strength, stiffness, and energy dissipation. Five specimens with different base plate thickness were numerically modelled using ABAQUS software. The numerical model is able to reproduce the key characteristics of the experimental response. Based on the numerical analysis, the critical base plate thickness to identify the base plate and anchor rod yield mechanism is proposed. For the connection with base plate yield mechanism, the resisting moment is carried by the flexural bending of the base plate. Yield lines in the base plate on the tension side and compression side are illustrated, respectively. This type of connection exhibits a relatively large energy dissipation. For the connection with anchor rod yield mechanism, the moment is resisted through a combination of bearing stresses of concrete foundation on the compression side and tensile forces in the anchor rods on the tension side. This type of connection exhibits self-centering behavior and shows higher initial stiffness and bending strength. In addition, the methods to predict the moment resistance of the connection with different yield mechanisms are presented. And the evaluated moment resistances agree well with the values obtained from the FEM model.