• Applied Chemistry for Engineering
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• v.4 no.2
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• pp.273-283
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• 1993

Addition of various acids or organic compounds to the electrolyte solution during the electrodeposition of $PbO_2$ on titanium madras substrate strongly affected performance of the deposited $PbO_2$ layer. Results of X-ray diffractometry ascertained that ${\beta}-PbO_2$ was deposited in acidic electrolyte. Among additives used in this experiment, $PbO_2$ with a high oxygen overvoltage was electrodeposited when sodium lauryl sulfate was added, and $PbO_2$ with a lower chlorine overvoltage was electrodeposited when polyethylene glycol was added to the electrolyte solution. The oxygen and chlorine overvoltage of $PbO_2$ was strongly dependent on the stirring provided during the electrodeposition experiment. It was observed by the SEM results that the $PbO_2$ grains deposited when stirring was not provided during the electrodeposition have larger than $PbO_2$ grains deposited by stirring. In the $PbO_2$ deposition under acidic electrolyte, the oxygen overvoltage increased with larger $PbO_2$ grains and the chlorine overvoltage decreased with smaller $PbO_2$ grains. The optimal current efficiency of $PbO_2$ in the presence of perchloric acid was observed at $Pb(NO_3)_2$ 560g/l, $65{\sim}70^{\circ}C$, and pH>1.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.148-148
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• 2011

Recently, there have been many research activities to develop the large-area plasma source, which is able to generate the high-density plasma with relatively good uniformity, for the plasma processing in the thin-film solar cell and display panel industries. The large-area CCP sources have been applied to the PECVD process as well as the etching. Especially, the PECVD processes for the depositions of various films such as a-Si:H, ${\mu}c$-Si:H, Si3N4, and SiO2 take a significant portion of processes. In order to achieve higher deposition rate (DR), good uniformity in large-area reactor, and good film quality (low defect density, high film strength, etc.), the application of VHF (>40 MHz) CCP is indispensible. However, the electromagnetic wave effect in the VHF CCP becomes an issue to resolve for the achievement of good uniformity of plasma and film. Here, we propose a new electrode as part of a method to resolve the standing wave effect in the large-area VHF CCP. The electrode is split up a series of strip-type electrodes and the strip-type electrodes and the ground ones are arranged by turns. The standing wave effect in the longitudinal direction of the strip-type electrode is reduced by using the multi-feeding method of VHF power and the uniformity in the transverse direction of the electrodes is achieved by controlling the gas flow and the gap length between the powered electrodes and the substrate. Also, we provide the process results for the growths of the a-Si:H and the ${\mu}c$-Si:H films. The high DR (2.4 nm/s for a-Si:H film and 1.5 nm/s for the ${\mu}c$-Si:H film), the controllable crystallinity (~70%) for the ${\mu}c$-Si:H film, and the relatively good uniformity (1% for a-Si:H film and 7% for the ${\mu}c$-Si:H film) can be obtained at the high frequency of 40 MHz in the large-area discharge (280 mm${\times}$540 mm). Finally, we will discuss the issues in expanding the multi-electrode to the 8G class large-area plasma processing (2.2 m${\times}$2.4 m) and in improving the process efficiency.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.71-71
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• 2011

Dye-sensitized solar cells (DSCs) have drawn great academic attention due to their potential as low-cost renewable energy sources. DSCs contain a nanostructured TiO2 photoanode, which is a key-component for high conversion efficiency. Particularly, one-dimensional (1-D) nanostructured photoanodes can enhance the electron transport for the efficient collection to the conducting substrate in competition with the recombination processes. This is because photoelectron colletion is determined by trapping/detrapping events along the site of the electron traps (defects, surface states, grain boundaries, and self-trapping). Therefore, 1-D nanostructured photoanodes are advantageous for the fast electron transport due to their desirable features of greatly reduced intercrystalline contacts with specified directionality. In particular, anodic TiO2 nanotube (NT) electrodes recently have been intensively explored owing to their ideal structure for application in DSCs. Besides the enhanced electron transport properties resulted from the 1-D structure, highly ordered and vertically oriented nanostructure of anodic TiO2 NT can contribute additional merits, such as enhanced electrolyte diffusion, better interfacial contact with viscous electrolytes. First, to confirm the advantages of 1-D nanostructured material for the photoelectron collection, we compared the electron transport and charge recombination characteristics between nanoparticle (NP)- and nanorod (NR)-based photoanodes in DSCs by the stepped light-induced transient measurements of photocurrent and voltage (SLIM-PCV). We confirmed that the electron lifetime of the NR-based photoanode was much longer than that of the NP-based photoanode. In addition, highly ordered and vertically oriented TiO2 NT photoanodes were prepared by electrochemical anodization method. We compared the photovoltaic properties of DSCs utilizing TiO2 NT photoanodes prepared by one-step anodization and two-step anodization. And, to reduce the charge recombination rate, energy barrier layer (ZnO, Al2O3)-coated TiO2 NTs also applied in DSC. Furthermore, we applied the TiO2 NT photoanode in DSCs using a viscous electrolyte, i.e., cobalt bipyridyl redox electrolyte, and confirmed that the pore structure of NT array can enhance the performances of this viscous electrolyte.

• Journal of the East Asian Society of Dietary Life
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• v.18 no.6
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• pp.1056-1062
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• 2008

To evaluate the effect of irradiation on restructured pork jerky containing paprika and Japanese apricot extracts, the quality of protein was determined in vitro based on the formation of trypsin indigestible substrate inhibitor (TIS) and the computed protein efficiency ratio (C-PER) as determined based on the protein digestibility and amino acid analysis. In addition, we compared the effects of electron beam irradiation to those of gamma irradiation. Approximately 3% of the moisture content of pork jerky was reduced in response to irradiation with 3kGy administered using an electron beam however, no additional reduction was observed in samples that were subjected to higher doses of irradiation. In addition, there were no notable differences in the crude protein and fat content of pork jerky samples that were subjected to irradiation, regardless of dose. Furthermore, the total amino acids profiles did not change in response to electron beam irradiation. However, the in vitro protein digestibility increased by 7% in response to 3kGy of electron beam irradiation and 5kGy of gamma irradiation, but no significant changes in digestibility were not observed in response to treatment with higher doses. TIS quantified as trypsin inhibitors were formed in response to irradiation using the electron beam (3kGy) and gamma rays (5kGy), although there was a slight reduction in the production of TIS inhibitors in samples irradiated with higher doses. Moreover, only samples irradiated with 10kGy (electron beam and gamma ray) showed higher TBA values than those of the control samples. Finally, the C-PERs $(2.50{\sim}2.60)$ were greater in all of the irradiated pork jerky samples than in the control samples (2.22). Taken together, these results suggest that electron beam irradiation and the incorporation of extracts (paprika and Japanese apricot) may be useful methods of improving the nutritional quality of pork jerky.

• Korean Journal of Agricultural Science
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• v.22 no.2
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• pp.134-142
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• 1995

In order to elevate the efficiency of methane fermentation using the paper mill sludge, this experiment was conducted at two temperature conditions($35^{\circ}C$ and $60^{\circ}C$), and overlooked the addition effects of ethyl acetate as a substrate, nickel as a constituent of $F_430$, and sulfur as a cell growth factor and reductant. The cellulose of paper mill sludge was degraded to lower molecular materials by heating at $60^{\circ}C$ and NaOH treatment. Methane forming rates were 4.8% from NaOH-treated paper mill sludge added with ethyl acetate, 16.5% with sodium sulfide, 19.8% with nickel trioxide, 31.9% with mixture, and 9.6% with control at $60^{\circ}C$, but 0.21% with ethyl acetate, 2.14% with nickel acetate, 3.02% with nickel sulfate, 3.34% with nickel trioxide and 0.62% with control at $35^{\circ}C$. Therefore, methane yield was increased by approximately 10-fold at $60^{\circ}C$ than $35^{\circ}C$, and fermentation liquid added with mixture(nickel trioxide+ethyl acetate+sodium sulfide) at $60^{\circ}C$ showed the medium pH(7.0), higher COD value and lower nitrogen content.

• Clean Technology
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• v.19 no.4
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• pp.355-369
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• 2013

Economic feasibility is one of the most important factors in energy production from regenerative biomass. From the aspect, biogas from anaerobic digestion of wastewater sludge is regarded as the most economical because of its cheap substrate and additional income from the disposal of waste sludge. Sludge hydrolysis has been regarded as the rate limiting step of anaerobic digestion and many sludge pre-treatment technologies have been developed to accelerate anaerobic sludge digestion for enhanced biogas production. Various sludge pre-treatment technologies including biological, thermo hydrolysis, ultrasonic, and mechanical methods have been applied to full-scale systems. Sludge pre-treatment increased the efficiency of anaerobic digestion by enhancing hydrolysis, reducing residual soilds, and increasing biogas production. This paper introduces the characteristics of various sludge pre-treatment technologies and the energy balance and economic feasibility of each technology were compared to prepare a guideline for the selection of feasible pre-treatment technology. It was estimated that thermophilic digestion and thermal hydrolysis were most economical technology followed by Cell rupture$^{TM}$, OpenCEL$^{TM}$, MicroSludge$^{TM}$, and ultrasound. The cost for waste sludge disposal shares the biggest portion in the economic analysis, therefore, water content of the waste sludge was the most important factor to be controlled.

• The Korean Journal of Mycology
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• v.42 no.3
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• pp.213-218
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• 2014

Water extract from spent mushroom substrates (SMS) of Pleurotus eryngii was utilized in decolorization of eight synthetic dyes and wastewater from a textile factory. High laccase activity was detected in the extract of P. eryngii (SMSE). The SMSE showed that decolorization rate was 34~93% after 24 h incubation without any mediator on eight dyes including Rit-blue and Rit-red used in fiber dyeing. Dye decolorization rate more than 90% was observed on bromophenol blue and remazol brilliant blue R (RBBR). Dye in textile wastewater was decolorized at room temperature after three days by addition of P. eryngii SMSE. The results suggest that biological decolorization of dyes using the P. eryngii SMSE can be used as environmental friendly materials.

• Membrane Journal
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• v.28 no.5
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• pp.307-319
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• 2018

Ion-exchange membrane (IEM) has fixed charge groups and is a separation membrane which is capable of selectively transporting ions of the opposite polarity. Recently, the interest in IEMs has been increasing as the importance of the desalination and energy conversion processes using them as the key components has increased. Since the IEMs determine the efficiency of the above process, it is necessary to improve the separation performance and durability of them and also to lower the expensive membrane price, which is a hindrance to the widening application of the IEM process. Therefore, it is urgent to develop high-performance and low-cost IEMs. Among various types of IEMs, pore-filled membranes prepared by filling ionomer into a porous polymer substrate are intermediate forms of homogeneous membranes and heterogeneous membranes. The production cost would be cheap like the case of heterogeneous membranes because of the use of inexpensive supports and the reduction of the amount used of raw materials, and at the same time, they exhibit excellent electrochemical characteristics close to homogeneous membranes. In this review, major research and development trends of pore-filled IEMs, which are attracting attention as high-performance and low-cost IEMs, have been summarized and reported according to the application fields.

• Korean Journal of Microbiology
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• v.36 no.4
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• pp.279-284
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• 2000

Simultaneous reduction of Cr(VI) and degradation of phenol was observed in batch and bench-scale continuous stirred tank reactors using Rhodococcus sp. CP01 isolated from leachate. The strain CP01, which was capable of utilizing phenol as a sole source of carbon and energy, completely reduced added hexavalent chromium (0.25 mM) to its trivalent form during 60 hr batch assay under optimal conditions (pH 7.0 and 1,000 mg/L of phenol concentration). The rates of Cr(VI) reduction and phenol degradation were estimated as 4.17 $\mu$M Cr(VI) and 38.4 mg phenol.$L^{-1}{\cdot}hr^{-1}$, respectively. The continuous culture experiment was conducted for 46 days using synthetic feed containing different levels of chromate (0.0625 to 0.25 mM) and phenol(1,000 to 4,000 mg/L). With a hydraulic retention time of 100 hr, Cr(VI) reduction efficiency was mostly 100% for influent Cr(VI) and phenol concentrations of 0.125 mM and 3,000 mg/L, respectively. During quasi-steady-state operation, specific rate of Cr(VI) reduction was calculated as 0.34 mg Cr(VI).g $protein^{-1}{\cdot}hr^{-1}$ which was comparable to reported values obtained by using glucose as growth substrate. The results suggest the potential application of biological treatment for detoxification of wastewater contaminated simultaneously with Cr(VI) and pheonol.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.5
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• pp.491-498
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• 2005

J sewage treatment plant (WWTP) in Busan has used methanol as an external carbon source for the biological denitrification process. Methanol is widely used. but rather expensive and very dangerous in handling. Therefore, it has been required that the economic alternative carbon source must be developed. By-product from a fine chemical industry can be Purified by removing high molecular weight substances using the ultrafilter membrane separation process and RBDCOD fraction becomes $98{\sim}99%$ of COD substances in the purified by-product. The purified by-product containing three types of alcohols, methanol, prophylenglycol and methoxypropanol; showed similar chemical characteristics to the methanol, a main external carbon source, in biodegradation pathway. Shown above, the compatibility between main and alternative carbon sources has been achieved. Also very short or no adaptation period is necessary in the case of exchanging these carbon sources. The compatibility between external carbon sources is an essential element for stabilizing WWTP operations. During the full-scale application test of the by-product, the alternative carbon source line got on par with the treatment efficiency of the methanol line. With the test result, J-WWTP changed methanol to a fine chemical by-product, in two out of three J-WWTP lines. Moreover, it is expected that 55.4% of the external carbon source cost reduction can be achieved in the alternative carbon source applied lines.