• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.12-16
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• 2000

This study is about the effect of braiding on the 2-D biaxial braided hollow composite(BD) compared with unidirectional hollow composite(UD). The specimens were made of T700S Carbon/Epoxy prepreg and T700S dried Carbon yarns. Fiber volume fraction of UD and BD was obtained experimentally and analytically. Fiber volume fraction of BD was derived based on unit cell of braiding yarn section. Bending test was executed to investigate the effect of braiding part. The result of experiment and analysis of fiber volume fraction has good agreement. Bending strength of BD is about 20% higher than that of UD.

• Journal of Korean Society of Steel Construction
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• v.25 no.3
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• pp.299-305
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• 2013

This paper presents the experimental results of behacior of slender square hollow section columns strengthened with carbon fiber reinforced polymers (CFRP) sheets subjected to concentrated axial loading. Three long specimens were fabricated and one stub column were fabricated. The main parameters were the number of CFRP layers. From the tests, it was observed that global buckling were occurred at the center of specimen for unretrofitting slender column. However, CFRP retrofitting could prevent the global buckling of slender column. Maximum increase of 22% was also achieved in axial-load capacity with three longitudinal layered CFRP applied on four sides of steel tubes.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.6
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• pp.550-557
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• 2013

A glucose hydrothermal method is described for preparing hollow carbon spheres (HCS), which have a regular morphology and a high Brunauer-Emmett-Teller surface area of 28.6 m2/g. Scanning electron microscopy shows that they have thin shells and diameter between 2 and 8 ${\mu}m$. The HCSs were modified for the enhanced room temperature hydrogen storage by employing Ni nanoparticles on their surface. The Ni-decorated HCSs were characterized by X-ray diffraction, transmission electron microscopy coupled with an energy dispersive spectroscope, and an inductively coupled plasma spectrometer, indicating that fine and well-distributed Ni nanoparticles can be accomplished on the HCSs. The hydrogen uptake capacity in HCSs with and without Ni loading was evaluated using a high-pressure microbalance at room temperature under a hydrogen pressure upto 9 MPa. As much as 1.23wt.% of hydrogen can be stored when uniformly distributed Ni nanoparticles are formed on the HCSs, while the hydrogen uptake capacity of as-received HCSs was 0.41 wt.%. For Ni nanoparticle-loaded HCSs, hydrogen molecules could be easily dissociated into atomic hydrogen and then chemically adsorbed by the sorbents, leading to an enhanced capacity for storing hydrogen.

• Structural Engineering and Mechanics
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• v.74 no.1
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• pp.145-156
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• 2020

There are separate merits and demerits to wood and steel. The combination of wood and steel as a compound section is able to improve the properties of both and ultimately increase their final bearing capacity. The composite cross-section made of steel and wood has higher hardness while showing more ductility and the local buckling of steel is delayed or completely prevented. The purpose of this study is to investigate the behavior of composite columns enclosed in wooden logs and the hollow sections of steel that will be examined in a laboratory environment under the axial load to determine the final bearing capacity and sample deformation. In terms of methodology, steel sheet and carbon fiber reinforced polymer sheet (FRP) are tested to construct hollow rectangular sections and reinforce timber. Besides, the method of connecting hollow sections and timber including glue and screw has been also investigated. As a result, timber lumber enclosed with carbon fiber-reinforced polymer sheets in which fibers are horizontally located at 90° are more resistant with better ductility.

• Computers and Concrete
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• v.24 no.3
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• pp.185-192
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• 2019

In this paper, the buckling of micro sandwich hollow circular plate is investigated with the consideration of the porous core and piezoelectric layer reinforced by functionally graded (FG)carbon nano-tube. For modeling the displacement field of sandwich hollow circular plate, the high-order shear deformation theory (HSDT) of plate and modified couple stress theory (MCST) are used. The governing differential equations of the system can be derived using the principle of minimum potential energy and Maxwell's equation that for solving these equations, the Ritz method is employed. The results of this research indicate the influence of various parameters such as porous coefficients, small length scale parameter, distribution of carbon nano-tube in piezoelectric layers and temperature on critical buckling load. The purpose of this research is to show the effect of physical parameters on the critical buckling load of micro sandwich plate and then optimize these parameters to design structures with the best efficiency. The results of this research can be used for optimization of micro-structures and manufacturing different structure in aircraft and aerospace.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.7
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• pp.64-70
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• 2022

The aim of this study is to improve the purification efficiency of odor gas by increasing the contact area between an odor gas and adsorbent. To analyze the flow in the adsorption tower, the flow characteristics in the hollow activated carbon-adsorption tower are identified by applying the loss model, which is a porous flow analysis model. The flow characteristics are investigated for pressure loss, velocity distribution, turbulent kinetic energy, and residence time distribution. The results show that the hollow adsorption tower performs better than the solid adsorption tower in terms of pressure loss and performance. The inner diameter of the hollow region inside the adsorption tower is 0.64 m (Di/Do = 0.37). Furthermore, the adsorbent performance is unaffected even when adsorbent stages are installed to replace the adsorbent.

• Membrane Journal
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• v.16 no.4
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• pp.252-258
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• 2006

A numerical analysis was performed for a separation process of carbon dioxide from a flue gas stream using polyethersulfone hollow fiber membranes. Countercurrent flow governing equations were regarded to be two point boundary-value problem and the nonlinear ordinary differential equation were simultaneously solved using the finite- difference method. A computer program was developed using the Compaq Visual Fortran 6.6 software. The carbon dioxide permeate driving force and the fred gas residence time at the inside of membrane were found to be very important factors affecting the permeation characteristics of carbon dioxide. The carbon dioxide concentration in the permeate and the flow rate of the permeate were found to be slightly larger by a few percent with a countercurrent flow analysis than those with a cocurrent flow analysis.

• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3274-3280
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• 2011

Monodispersed porous NiO and $Co_3O_4$ microcapsules with a hollow core were synthesized using SBA-16 silica sol and PS as a hard template. The porous hollow microcapsules were characterized by XRD, TEM and $N_2$ adsorption/desorption analysis. After $H_2$ reduction of metal oxide microspheres, they were conducted as an active catalyst in the reduction of chiral butylronitrile and cyanobenzene. The mesoporous metals having a hollow structure showed a higher activity than a nonporous metal powder and an impregnated metal on the carbon support.

• Journal of the Korean Society for Heat Treatment
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• v.25 no.2
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• pp.80-84
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• 2012

An apparatus was constructed to nitrify small metallic sintered components by using a hollow-cathode discharge plasma method. A stainless steel basket, which contains a sintered part to be nitrified, is potentially grounded and serves as hollow-cathode electrode. Hollow-cathode plasma was produced by supplying the positive voltage to the anode. In this study sintered carbon iron and stainless steel were used as testing specimens. It was shown that an effective nitrifying took place by controlling the total pressure of nitrogen and hydrogen gas and applied voltage.

• Membrane Journal
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• v.33 no.4
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• pp.222-232
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• 2023

In this study, a hollow fiber support membrane was prepared by a non-solvent induced phase separation (NIPS) method using a polysulfone (PSf). The prepared hollow fiber support membrane was coated with PDMS and Pebax to prepare a hollow fiber composite membrane. The prepared composite membrane was measured for permeance and selectivity for pure CO₂, H₂, O₂ and N₂. Gas separation performance of the module having the highest selectivity (CO₂/H₂) among the prepared composite membrane modules was measured according to the change in stage cut using simulated gas. The composition of the simulated gas used at this time was 70% CO₂ and 30% H₂. In the 1 stage experiment, it was possible to obtain values of about 60% of H₂ concentration and 12% of H₂ recovery. In order to overcome the low H₂ concentration and recovery, 2 stage serial test was performed, and through this, it was possible to achieve 70% H₂ concentration and 70% recovery. Through this, it was possible to derive a separation process configuration for CO₂/H₂ separation.