• 한국생물공학회:학술대회논문집
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• 2004.07a
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• pp.107-125
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• 2004

A bioremediation of petroleum-contaminated soil in Korea was evaluated for the optimization of enhanced biodegradation and the minimization of effects of seasonal variations, The short-term bioremediation in combination of biopile pretreatment and landfarming was performed by lowering contaminated levels and overcoming the inhibiting factors in the rainy and winter seasons. A microbial density was maintained with indigenous microbial addition for bioaugmentation and with fertilizers for biostimulation. A lesser volatile and biodegradable fraction due to their abiotic removals following the biopile pretreatment was effectively removed by the laterally applied landfarming. The optimal temperature in greenhouse was maintained by buffering of the soil temperature even with slight decreases in removal rates during the winter and extensive leaching of nutrients and contaminants was restricted with adjusting the water contents during the Korean rainy season. Although the tilling process was effective for biodegradation with aeration only, the simultaneous treatment due to apparent mixing of nutrients and microbes more favorably degraded the petroleum than the sequential treatment.

• Journal of the Korean Home Economics Association
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• v.42 no.4
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• pp.119-125
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• 2004

In this paper, the effect of the volcanic ash dyed on cotton knitted fabrics was studied in various ways. A cationic agent was used to improve the depth of color of the fabric in the dyeing process. K/S values of dyed fabrics were measured to examine the dyeing properties. Cationic agent pretreatment, followed by dyeing with volcanic ash, was tested. In the dyeing experiment, the effects of a wide range of parameters such as the concentration of cationic agent, treatment time, treatment temperature and treatment pH of the dyebath were studied. Experimental results showed that the pretreatment with cationic agent improved the dyeing properties of cotton knitted fabrics with volcanic ash. At this point, concentration of cationic agent was 4%(on weight of fabric), treatment time was 40minutes, treatment temperature was 80 C and treatment pH of the dyebath was a neutral condition.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.511-511
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• 2009

Lignocellulosic biomass is the most abundant organic material on earth and also promising raw material for bioenergy production. Agricultural residues in the process of bio-oil extraction, is an abundant and low-cost lignocellulosic material. The technology for conversion of lignocellulosic biomass resources to fuels and chemicals, such as ethanol, has been under development for decades. One of the well-studied technologies that are currently being commercialized is to use a dilute acid-catalyzed pretreatment followed by enzymatic hydrolysis and fermentation to produce ethanol. In this work, the dilute-acid hydrolysis of agricultural residues was optimized through the utilization of statistical experimental design. Evaluation criteria for optimization of the pretreatment conditions were based on high xylose recovery and low inhibitor contents in the hydrolyzates. The purpose of this study was to gain a more accurate understanding of the quantities of acid required for effective hydrolysis and the reactivity trade-offs with reaction time and temperature that will enable overall process optimization.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.6
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• pp.501-506
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• 2006

Carbon nanotubes (CNTs) were grown with a microwave plasma enhanced chemical vapor deposition (MPECVD) method, which has been regarded as one of the most promising candidates for the synthesis of CNTs due to the vertical alignment, the low temperature and the large area growth. MPECVD used methane ($CH_4$) and hydrogen ($H_2$) gas for the growth of CNTs. 10 nm thick Ni catalytic layer were deposited on the Ti coated Si substrate by RF magnetron sputtering method. In this work, the pretreatment was that the Ni catalytic layer in different microwave power (600, 700, and 800 W). After that, CNTs deposited on different pressures (8, 12, 16, and 24 Torr) and grown same microwave power (800 W). SEM (Scanning electron microscopy) images showed Ni catalytic layer diameter and density variations were dependent with their pretreatment conditions. Raman spectroscopy of CNTs shows that $I_D/I_G$ ratios and G-peak positions vary with pretreatment conditions.

• Korean Journal of Materials Research
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• v.21 no.12
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• pp.673-678
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• 2011

With an increased production of Printed Circuit Boards (PCBs) in electronic equipment, the consumption of solder alloys is growing globally. Recently, increasing importance of recycling solder scrap has been recognized. Generally, solder scrap contains many impurities such as plastics and other metals. Hazardous components must be eliminated for recycling solder scrap. The present work studied pretreatment for reuse of solder scrap alloys. An experiment was conducted to enhance the cleanliness of solder scrap melt and eliminate impurities, especially lead. Physical separation with sieving and magnetic force was made along with pyrometallurgical methods. A small decrease in lead concentration was found by high temperature treatment of solder scrap melt. The impurities were removed by filtration of the solder scrap melt, which resulted in improvement of the melt cleanliness. A very low concentration of lead was achieved by a zone melting treatment with repeated passage. This study reports on a pretreatment process for the reuse of solder scrap that is lead free.

• Current Optics and Photonics
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• v.5 no.3
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• pp.322-328
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• 2021

In this paper, a pretreatment method for a matrix in convex optimization is proposed to optimize the spectral reconstruction process of a disordered dispersion spectrometer. Unlike the reconstruction process of traditional spectrometers using Fourier transforms, the reconstruction process of disordered dispersion spectrometers involves solving a large-scale matrix equation. However, since the matrices in the matrix equation are obtained through measurement, they contain uncertainties due to out of band signals, background noise, rounding errors, temperature variations and so on. It is difficult to solve such a matrix equation by using ordinary nonstationary iterative methods, owing to instability problems. Although the smoothing Tikhonov regularization approach has the ability to approximatively solve the matrix equation and reconstruct most simple spectral shapes, it still suffers the limitations of reconstructing complex and irregular spectral shapes that are commonly used to distinguish different elements of detected targets with mixed substances by characteristic spectral peaks. Therefore, we propose a special pretreatment method for a matrix in convex optimization, which has been proved to be useful for reducing the condition number of matrices in the equation. In comparison with the reconstructed spectra gotten by the previous ordinary iterative method, the spectra obtained by the pretreatment method show obvious accuracy.

• Journal of the Korean Wood Science and Technology
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• v.52 no.2
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• pp.101-117
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• 2024

The conversion characteristics of the major components of Liriodendron tulipifera were investigated during acid-catalyzed organosolv pretreatment. Glucan in L. tulipifera was slowly hydrolyzed, whereas xylan was rapidly hydrolyzed. Simultaneous hydrolysis and degradation of xylan and lignin occurred; however, after complete hydrolysis of xylan at higher temperatures, lignin remained and was not completely degraded or solubilized. These conversion characteristics influence the structural properties of glucan in L. tulipifera. Critical hydrolysis of the crystalline regions in glucan occurred along with rapid hydrolysis of the amorphous regions in xylan and lignin. Breakdown of internal lignin and xylan bonds, along with solubilization of lignin, causes destruction of the lignin-carbohydrate complex. Over a temperature of 160℃, the lignin that remained was coalesced, migrated, and re-deposited on the surface of pretreated solid residue, resulting in a drastic increase in the number and content of lignin droplets. From the results, the characteristic conversions of each constituent and the changes in the structural properties in L. tulipifera effectively improved enzymatic hydrolysis in the range of 140℃-150℃. Therefore, it can be concluded that significant changes in the biomass recalcitrance of L. tulipifera occurred during organosolv pretreatment.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.505-505
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• 2009

The object is to optimize the best condition of organosolv pretreatment process with sulfuric acid as a catalyst. As a material, Pitch pine (Pinus rigida) was ground and sieved through 40-mesh screen, and Celluclast and $\beta$-glucosidase were used as enzymes for enzymatic hydrolysis. Pretreatment processes were carried out in the minibomb, and 20 g of materials with 200 ml of 50% ethanol solution (v/v) with 1% sulfuric acid as a catalyst. Pretreatment temperature was varied from $150^{\circ}C$ to $190^{\circ}C$, and time was varied from 0 to 20 min. Then, residual materials were used for enzymatic hydrolysis. The best conditions were selected by estimating followed enzymatic hydrolysis rate and degradable rates after pretreatment process. The highest value of enzymatic hydrolysis rate was obtained as 55 - 60% at 160 and at $180^{\circ}C$, but the value decreased under more severe conditions. As the residual rates decreased under severe conditions, it infered that the decrease of sugar contents limits enzymatic hydrolysis rates. Combined with enzymatic hydrolysis rate, degradable rates and H-factors, the temperatures at $160^{\circ}C$ for 20 min and at $180^{\circ}C$ for 0 min were concluded as the optimized conditions where have the lowest H-factor value for considering energy input.

• Journal of the Korean Wood Science and Technology
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• v.47 no.2
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• pp.145-162
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• 2019

This study aimed to increase the sugar and ethanol yield from the mengkuang plant biomass through biological and liquid hot water (LHW) pretreatment and their combination. The results showed that biological pretreatments with 5% inoculum of the fungus Trametes versicolor resulted in the highest alpha cellulose content incubated for 30 days, and 10% inoculum resulted in the lowest lignin content. LHW pretreatment decreased the hemicellulose content of pulps from 10.17% to 9.99%. T. versicolor altered the structure of the mengkuang pulp by degrading the lignin and lignocellulose matrix. The resulting delignification and cellulose degradation facilitate the hydrolysis of cellulose into sugars. The alpha cellulose content after biological-LHW pretreatment was higher (78.99%) compared to LHW-biological pretreatment (76.85%). Scanning electron microscopy analysis showed that biological-LHW combinated treatment degrades the cell wall structures. The ethanol yield for biological-LHW pretreated sample was observed 43.86% (13.11 g/L ethanol by weight of the substrate, which is much higher than that of LHW-biological pretreatment (34.02%; 9.097 g/L). The highest reducing sugar content about 45.10% was observed with a resulting ethanol content of 15.5 g/L at LHW pretreatment temperature of $180^{\circ}C$ for 30 min.

• Journal of the Korean Applied Science and Technology
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• v.36 no.4
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• pp.1243-1252
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• 2019

The purpose of this study is to investigate the optimum conditions of biomass pretreatment with potassium hydroxide (KOH) for efficient utilization of cellulose, hemicellulose and lignin from Miscanthus. The optimization of variables was performed by response surface methodology (RSM). The variation ranges of the parameters for the RSM were potassium hydroxide 0.2~0.8 M, reaction temperature 110~190℃ and reaction time 10~90 min. The optimum conditions of alkali pretreatment from Miscanthus were determined as follows: concentration of KOH 0.47 M, reaction temperature 134℃ and reaction time 65 min. At the optimum conditions, the yield of cellulose from the solid fraction after pretreatment was predicted to be 95% by model prediction. Finally, 66.1 ± 1.1% of cellulose were obtained by verification experiment under the optimum conditions. The order contents of solid extraction were hemicellulose 26.4 ± 0.4%, lignin 3.7 ± 0.1% and ash 0.5 ± 0.04%. The yield of ethanol concentration of 96% was obtained using separated saccharification and fermentation.