• Proceedings of the Korean Society of Laser Processing Conference
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• 2005.06a
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• pp.32-39
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• 2005

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.10
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• pp.865-871
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• 2014

This study was conducted with the aim of developing a venturi-type air supply system for a microbubble generator. In order to determine the influence of the varying geometry of the venturi tube on the flow characteristics, a computational fluid dynamics (CFD) simulation was performed using the commercial CFD software ANSYS CFX-15. Furthermore, in order to elucidate the effects of variation in major design dimensions such as the air supply hole size, position of holes, and number of holes on the air supply characteristics, two-phase multiflow CFD analysis was performed. The analysis results showed that the starting point of expansion on the venturi tube with 0.75 is the best hole position and that the air supply hole size and the number of holes are linearly proportional to the amount of air.

• Applied Biological Chemistry
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• v.36 no.3
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• pp.172-177
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• 1993

To extract insoluble proteins from sesame meal residue by microorganism, the sesame meal residue was treated with crude enzyme solution of Bacillus sp. CW-1121. The foaming capacity of salt soluble protein was quite lower than that of water soluble protein and the foaming stability of salt soluble protein decreased abruptly in 10 min., while it sustained for 30 min in case of water soluble protein. Emulsion capacities of all the protein fractions showed minimum value near isoelectric point of protein and salt soluble protein had lower emulsion capacities than that of water soluble protein. The emulsion stability of the protein was relatively stable for 30 min at $80^{\circ}C$. Oil and water absorption capacities of salt soluble protein were higher than those of water soluble protein.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2005.10a
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• pp.75-82
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• 2005

Pyrolysis of biomass is one of the promising methods to obtain energy and valuable chemical stocks. Fast pyrolysis of Q. acutissima and L. letolepis has been carried out in a bubbling fluidized bed reactor to determine the optimum operating conditions of the pyrolyzer. Effects of reaction temperature, Uo/Umf, L/D ratio, and feed rate have been determined and the optimum conditions are as follows: $T\;=\;400^{\circ}C,\;U_o/U_{mf}\;=\;3.0,\;L/D\;=\;2.0$. Maximum yield of bio-oil was about 55% and the main compositions were carbohydrates, guaiacols, furans, phenols, and syringols. Product gas was consists of CO, $CO_2$, light hydrocarbons and the measured gas yield using the compositions agreed with the calculated value.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.5
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• pp.212-221
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• 2010

The bubbles could be created from multiple source in the surface of ocean. The bubbles which are created like this affect to the intensity and the sound speed of acoustic wave which are used from the ocean. From the research, it observed Reverberation from the sea surface, using Vbeam transmission and reception equipment that was a cross-shaped Array, from 2008 July 2nd to July 3rd at 4Km from the East Sea Mookho port. It is difficult to analyze data because the received signal has ambient noise and occurrence ISI(Inter Symbol Interference) for multipath. This paper remove that ambient noise and ISI using the directions of arrival beamforming and the filter and sum beamforming. After beamforming, a following DFE(Decision Feedback Equalizer) removes the remaining multipath components. Experimental results show that the proposed technique reduce the errors caused by ISI.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.197-197
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• 2003

현재 PDP(Plasma Display Panel) 투명유전체층은 PbO 계열을 사용하고 있으나 제조공정 시 다량의 중금속 페기물이 방출됨에 따라 환경오염을 야기시킴으로 무연조성이며 저온소성이 가능한 저융점유리인 인산염계 유리에 대한 열적, 화학적, 광학적 특성에 대해 체계적인 연구가 진행되었다. 광학적 특성을 위 한 승온속도, 소성온도, 유지시간의 변화 그리고, 프릿 입도에 따른 광 투광성, 기포의 형성, 그리고 기포의 분포특성을 연구하였다. 열적특성은 DTA와 TMA를 이용하여 유리전이점(Tg) 및 선팽창계수(CTE)와 Littleton softning point (Ts)가 측정되었다. 광학적특성은 스크린프린팅법으로 후막 제조 후 소성하여 UV-visible spectrometer을 이용하여 300~800nm영역에서 투광성을 측정하였으며, FEG-SEM, AFM을 이용해 표면을 관찰하였다. 결과로써, Tg는 440-46$0^{\circ}C$ 와 CTE는 7~8.5$\times$$10^{-6}$K값을 보였고 높은 화학적 내구성과 60-80%의 광투과율을 나타내었다. 프릿의 미세화, 숭온속도의 감소는 기포의 생성을 줄이는데 효과를 보였으며, 그 결과 양호한 광투과율을 얻을 수 있었다. 이러한 결과에 따르면, P$_2$O$_{5}$-ZnO-RO 조성은 PDP용 투명유전체 조성으로써 기존의 PbO계열을 대체할만한 새로운 조성으로 고려된다.

• Composites Research
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• v.18 no.3
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• pp.47-52
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• 2005

Pultrusion process of phenolic foam composite is investigated. Phenolic foam composites provide heat and flame resistance with less weight. When made into foam, a variety of properties can be obtained with different bubble size and number density. In this study, effect of process variables on the foaming characteristics of phenolic resin composites during pultrusion process has been studied experimentally. The process variables considered are the heating temperature and the pulling speed as well as the mass fraction of blowing agent. Experiments were performed using a laboratory scale pultrusion apparatus. Optimal process condition was found by observing the micro-morphology.

• Nuclear Engineering and Technology
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• v.24 no.1
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• pp.40-51
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• 1992

One of the important irradiation performance characteristics of the silicide dispersion fuel element in research reactors is the diameteral increase resulting from fuel swelling. This paper, will attempt to develop a physical model for the fuel swelling, DFSWELL, by analyzing the basic irradiation behaviours and some experimental evidences. From the experimental evidences, it was shown that the volume changes in irradiated U$_3$Si-Al were strongly dependent on temperature and fission rate. The quantitative-amount of swelling for silicide fuel is estimated by considering temperature, fission rate, solid fission product build-up and gas bubble behavior. The swelling for the silicide fuel is comprised of three major components : i ) a volume change due to the formation of an interfacial layer between the fuel particle and matrix. ii ) a volume change due to the accumulation of gas bubble nucleation iii ) a volume change due to the accumulation of solid fission products The DFSWELL model which takes into account the above three major physical components predicts well the absolute magnitude of silicide fuel swelling in accordance with the power histories in comparison with the experimental data.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1010-1015
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• 2003

Bubble growth on microheater has been experimentally investigated in this study. The experiment was performed using platinum microheaters having dimensions of 300 ${\mu}m$ or 50 ${\mu}m$ in length, 20 ${\mu}m$ or 5 ${\mu}m$ in width, and $0.2{\pm}0.01$ ${\mu}m$ in thickness. A high speed video camera was used to observe bubble growth at 2,000 frames per second. Microheater temperature was measured at the rate of 300 Hz. with a data acquisition system. Bubble nucleation frequency increased with working fluid temperature. Although the slope of temperature drop was similar in all cases, the magnitude of temperature drop was different. The temperature profiles and the high speed camera images were combined to explain temperature drop.

• Korean Journal of Crystallography
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• v.5 no.2
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• pp.67-77
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• 1994

From the Y3-3xNd3xAl5O12single crystals grown by the Czochralski technique, various types of defects were detected and 1) the reason of opical in homogeneous phases, 2) the mechanism of formation of the iridum metal inclusions accompanying bubbles, and 3) the mechanism of formation of the core and facet were analysed After preparing the wafers of the <111> growth parallel, defscts were observed by the polarising microscope using a photoelasic effect and then some images of stress-birefringence were compared to their etch Pits patterns.