• Journal of Korean Society of Environmental Engineers
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• v.27 no.5
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• pp.468-475
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• 2005

Biofilters packed with various materials have emerged as a sustainable technology for the treatment of volatile organic compounds (VOCs); however, problems including low performance and clogging are commonly encountered. Recently, a bioactive foam reactor (BFR) using surfactants has been suggested to ensure efficient and stable VOCs removal performance. This study was mainly conducted to investigate the feasibility of BFRs using toluene as a model compound. Prior to bioreactor studies, a series of bottle tests were used to select a suitable surfactant for the BFR application. Experimental results of the batch bottle tests indicated that TritonX-100 was the most appropriate one among the surfactants tested, since it showed a minimal effect on the toluene biodegradation rate while the other surfactants lowered the toluene biodegradation rate significantly. Using the selected surfactant, the BFR performance was determined by changing operating parameters including gas residence time and toluene loading. As the gas residence time increased from 0.5 minutes to 2 minutes, the toluene removal efficiency increased from approximately 50% to 80%. In addition, an increase of the toluene loading from $38\;g/m^3/hr$ to $454\;g/m^3/hr$ resulted in a decrease of toluene removal efficiency from approximately 70% to 20%. The BFR had a maximum elimination capacity of $108\;g/m^3/hr$ for toluene, which was much higher than those generally reported in the literature. The high toluene-elimination performance indicates that the BFR be a potential alternative to the conventional, packed-type biofilters. However, the limitation of toluene solubilization and foam stability at either high or low gas flow rate are still problems to be challenged.

• Korean Journal of Food Science and Technology
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• v.20 no.5
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• pp.625-630
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• 1988

Phosphorylation of soy protein by sodium trimetaphosphate and acetylation of soy protein by acetic anhydride were performed. Then, the functional properties of modified soy proteins were compared with that of unmodified soy protein. Isolated soy protein prepared from defatted soybean flake had protein content of 92.7% as moisture-free basis. The phosphorylated soy protein showed higher solubility, foaming properties, and water holding capacity than unmodified soy protein. Acetylation of soy protein increased emulsification activity and foaming properties greatly, whereas decreased the solubility at pH 8.0. Isoelectric pHs of phosphorylated and acetylated soy protein were shifted to acidic regions(pH 3.0 and pH 4.0) from pH 5.0, which was the isoelectric pH of unmodified soy protein. Soy protein seems to be aggregated during phosphorylation and acetylation procedure, judging form Sepharose CL-4B gel filtration profiles. The modified soy proteins showed increased mobilities to anode direction in disc-gel electrophoresis.

• Resources Recycling
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• v.8 no.5
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• pp.19-27
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• 1999

The desilica~ilalioc~h~ar .~ctcrisocs or conveutcu dust for molten pg iron has bee11 sludled for the pulposc of converter dust reuse. Desiloconizalir~ne ff~c~encwya s observed 10 be increased with increasing feeding rate of dust, and there was 110 cffccl to Lhe des~lica~~iratiearlfli cio~cyfo r the addtioolI CaO Ln dust. In ~noslc ases, the dcs~l~conizaliornea ction was ucconlpl~shed wrthin 10 minutes regadless of thc dust cornpasilim In addition lo the desil~comzat~oenfl ect, the rzmow~lc hal-i~cteristo~fs M u, P. C, and S from mallen iron by convcrtcr dust also have been in\~esligataled. CuO m thc converlel. dust was observed to ~educc the demanganizi~tion eflect and slag laming phenomenon and make thc dephosphoriralion pn,ce*s easler.

• Korea Real Estate Review
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• v.27 no.1
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• pp.33-44
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• 2017

The continuously rising housing prices in major Chinese cities have raised question about whether inflation is the main reason to drive up housing price to skyrocket in recent years. Based on the provincial panel dataset of China from 2006-2014, this paper investigates the impact of inflation on Chinese housing markets within the frameworks of both static and dynamic panel data models. Our empirical results show evidence that inflation has indeed been a main force of accumulating housing bubbles in these housing markets, especially in eastern region of China. We also find an interesting phenomenon in which Chinese housing bubble is, to a certain extent, affected by market self-adjustment mechanism.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.4
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• pp.363-368
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• 2010

In the solid rocket propellant combustion, the dynamic phase change from solid to liquid to vapor occurs across the melt layer. During the surface burning, liquid and gas phases are mixed in the intermediate zone between the propellant and the flame to form micro scale bubbles. The known thickness of the melt layer is approximately 1 micron at $10^5$ Pa. In this paper, we present a model of the melt layer structure and the dynamic motion of the melt front derived from the classical phase field theory. The model results show that the melt layer grows and propagates uniformly according to exp(-1/$T_s$) with $T_s$ being the propellant surface temperature.

• Korean Chemical Engineering Research
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• v.51 no.4
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• pp.527-530
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• 2013

I present the behavior of colloidal adsorption to an oil-water interface in the presence of electrolyte in an aqueous subphase. The optical laser tweezers and the piezo controller are used to trap an individual polystyrene microsphere in water and forcibly transfer it to the interface in the vertical direction. Addition of an electrolyte (i.e., NaCl) in the aqueous subphase enables the particle to attach to the interface, whereas the particle escapes from the trap without the adsorption in the absence of the electrolyte. Based on the analytical calculations of the optical trapping force and the electrostatic disjoining pressure between the particle and the oil-water interface, it is found that a critical energy barrier between them should exist. This study will provide a fundamental understanding for applications of colloidal particles as solid surfactants that can stabilize the immiscible fluid-fluid interfaces, such as emulsions (i.e., Pickering emulsions) and foams.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6B
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• pp.689-694
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• 2006

The system performance of a bioactive foam reactor (BFR), that consists of a foam column using a surfactant and a biodegradation basin containing suspended bacteria, was investigated for the treatment of gaseous toluene or a mixture of four volatile organic compounds (VOCs, benzene, toluene, p-xylene, and styrene). Overall, the BFR achieved stable VOC removal efficiencies, indicating that it can be used as a potential alternative over conventional packed-bed biofilters. Furthermore, a dynamic loading test showed that relatively constant removal was maintained at the elevated loading due to a high mass transfer rate in the foam column. However, as the inlet concentration of VOCs increased, a portion of the VOCs mass-transferred to the liquid phase was stripped out from the biodegradation basin, resulting in a decrease in the overall removal efficiency. In the BFR, the removal efficiency of the individual VOC was mainly determined depending on the biodegradation rate (styrene > toluene > benzene > p-xylene), rather than the mass transfer rate. Consequently, increases in the microbial activity and the volume of the basin could improve the overall performance of the BFR system. Further investigation on microbial activity and community dynamics is required for the BFR when subjected to high loadings of VOC mixtures.

• The Korean Journal of Financial Studies
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• v.8 no.1
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• pp.157-188
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• 2002

본 연구는 우리나라 IPO시장에서 나타나고 있는 초과수익률의 원인을 밝히고자 최근 벤처금융의 중심으로 급부상하고 있는 KOSDAQ시장의 공모 IPO를 대상으로 실증분석을 시도하였다. 연구결과 상장일 표본전체 IPO의 초과수익률(AR1)이 9.91%로 나타났으며, 벤처캐피탈투자 IPO는 5.13%, 비투자 IPO는 13.29%로 나타났다. 상한가의 행진이 종료된 날을 기준으로 한 표본전체 IPO의 초과수익률(AR2)은 30.97%, 벤처캐피탈 투자기업 IPO는 24.34%, 비투자기업 IPO는 34.67%로 나타났다. 초과수익률의 원인을 분석하기 위한 8개의 변수 중 IPO의 수요증감 척도인 KOSDAQ 지수는 초과수익률(AR)과는 양(+)의 관계로, 벤처캐피탈리스트들의 능력 및 가치책정의 행태를 엿볼 수 있는 변수인 본질가치와 공모가액의 차이는 음(-)의 관계로, 사업규모나 자본조달의 크기를 엿볼 수 있는 공모금액의 크기는 양(+)의 관계로 1% 유의수준에서 유의한 것으로 나타났다. 그러나 여타 변수들은 통계적으로 유의성을 확보하지는 못하였으나 초과수익률의 원인이론으로 '신호이론'과 '투기적 거품가설'에 의한 설명이 가능하였으며 분석결과를 다음과 같이 정리할 수 있었다. 첫째, IPO 본질가치에 대한 신뢰와 IPO의 발행규모에 대한 신뢰수준이 통계적으로 유의한 결과로 나타났는바 이러한 결과는 기업가치와 벤처 또는 사업의 계속적 수행 등에 대한 신호역할을 수행하고 있다고 할 수 있으며 상장초기 초과수익률은 주로 이러한 신호역할에 의한 수요집중으로 발생된 결과인 것으로 사료되었다. 둘째, 노련한 벤처캐피탈회사로 선정된 KTB의 투자기업들은 상장 후 4주간의 거래에 있어 AR 평균이 음(-)으로 여타 벤처캐피탈이 투자된 기업보다 손실 폭이 더욱 켰음에도 불구하고 상장일 초과수익률 AR2가 매우 높게 나타나 우리나라 IPO시장에 있어 과민반응(fads) 현상이 존재하고 있는 것으로 분석되었다. 셋째, 벤처캐피탈 투자 IPO의 초과수익률이 상대적으로 낮아 벤처캐피탈 투자여부가 IPO의 저가발행 수준을 축소하고 있어 벤처캐피탈리스트의 제 3자 보증역할이 어느 정도는 수행되고 있는 것으로 분석되었다.

• Childhood Kidney Diseases
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• v.16 no.1
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• pp.21-31
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• 2012

Focal segmental glomerulosclerosis (FSGS) is the name of the primary glomerular disease as well as the terminology to describe the secondary phenomena of any other glomerular diseases. It is characterized by sclerosis, hyalinosis, foam cell infiltration, vacuolar change of podocytes, and halo formation in the glomerulus. Throughout the interstitium, lymphocytes infiltration, tubular atrophy and vascular changes are accompanied. Occasionally, IgM and/or C3 depositions are noted in the sclerotic areas. Electron microscopically, diffuse effacement of foot processes are seen in non-sclerotic area like minimal change disease. Podocyte injury patterns including vacuolar changes are frequently examined. Recently, Columbia group has suggested morphologic classification of FSGS and they demonstrated very good prognosis of tip lesion and poor prognosis of both collapsing and cellular types. However, the pathogenetic classification has been suggested by others; hyperfilteration, podocyte injury, genetic lesions etc. Further studies are necessary to understand and treat this disease.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.7
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• pp.770-775
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• 2006

Biofilters packed with various materials commonly show problems such as low performance and clogging in a long-term operation. Recently, a bioactive foam reactor(BFR) using surfactants has been suggested to ensure efficient and stable VOCs removal performance. This study was mainly conducted to investigate the feasibility of the BFR system using styrene as a model compound. An abiotic md a biotic tests were conducted to estimate a mass transfer coefficient($K_La$) and a specific substrate utilization coefficient(k) for the BFR, showing the rate of mass transfer was greater in the BFR than in other diffuser systems. A dynamic loading test also indicated that the performance of the BFR was stable under a shock loading condition. Furthermore, the maximum elimination capacity of the BFR was determined to be 109 $g/m^3/hr$ for styrene, which was much higher than those for biofilter systems generally reported in the literature. Overall, the experimental results suggest that the BFR be a potential alternative to the conventional packed-bed biofilters.