• Journal of the Korean Wood Science and Technology
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• v.42 no.2
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• pp.172-182
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• 2014

Extraction is a necessary element in the bioconversion of lignocellulosics to fuels and chemicals. Although various forms of chemical pretreatment of cellulosic materials have been proposed, their effectiveness varies depending on the treatment conditions and substrate. In this study, mixed hardwood (MH) and loblolly pine (LP) were pretreated with dilute acid in a 100 mL accelerated solvent extraction (ASE) at the predetermined optimal conditions: temperature: $170^{\circ}C$, acid concentration: 0.5% (w/v), and reaction time: 2~64 min. This method was highly effective for extracting the hemicellulose fraction. Total xmg (defined as the sum of xylose, mannose, and galactose) can be extracted from milled MH and LP through pressurized dilute acid treatment in maximum yields of 12.6 g/L and 15.3 g/L, respectively, representing 60.5% and 70.4% of the maximum possible yields, respectively. The crystallinity index increased upon pretreatment, reflecting the removal of the amorphous portion of biomass. The crystalline structure of the cellulose in the biomass, however, was not changed by the ASE extraction process.

• Journal of Life Science
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• v.6 no.1
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• pp.14-26
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• 1996

In order to effectively utilize fish(Cod, Gadus macrocephalus) bone obtained as fish waste in fish manufactory, the preparation of the fish bone gelatin were attempted by heat extracting method from collagen protein contained in the fish bone. The methods of two kinds pretreatments (the B-type by alkali pretreatment and the E-type by enzyme pretreatment) for fish bone and the optimal extraction conditions to prepare gelatin from pretreated fish bone were investigated. Physical properties and functionalities of the two type fish bone gelatins obtained were compared with the commercial gelatin and the fish skin gelatin. The optimal extraction conditions of the B-type and the E-type gelatins were 5 folds of added water with material(w/w), pH 5.0, 3 hrs of extraction time and 60$\circ$C of extraction temperature. The yield of the B-type and the E-type gelatins were 32.6% and 28.1 %, respectively. The B-type gelatin was superior to the E-type un all physical properties. Molecular weight of the B-type was larger than that of the E-type due to its pretreatment method. Among the composition of amino acids, the amino acids such as glycine, alanine, glutamic acid and imino acids(proline and hydroxyproline) were responsible for 68$\sim$70% of the total amino acids. Functionalities of the fish bone gelatin were almost similar to commercial gelatin.

• KSBB Journal
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• v.25 no.4
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• pp.357-362
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• 2010

Green alga, Ulva pertusa kjelmann has been known to be one of the largest pollutants in Korea. Therefore, the efficient pretreatment processes have been required to improve the yields of fermentable sugar. The optimal pretreatment conditions were determined to be $195^{\circ}C$ for 15 min. The sugar yield of glucose and xylose were estimated as 20.5%, and 5.0% respectively, based on theoretical yields. However solid residues were estimated enzymatic digestibility of 90-95% with cellulase loading of 15 FPU/g glucan. This process was proved to generate the low concentration of Hydroxy-Methyl-Furfural (51 ppm), which resulted in ethanol production with 95% of the maximum conversion yield from glucose in the culture of Saccharomyces cerevisiae (ATCC, 24858). This study showed that Ulva pertusa kjellmann can be used as a bioetahnol resource using the high temperature liquefaction process.

• Applied Chemistry for Engineering
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• v.19 no.6
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• pp.690-692
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• 2008

Pure glycerol could be obtained from a biodiesel byproduct by separation processes including neutralization, precipitation, and distillation. The contents of distilled glycerol through the above separation processes were measured and the results were compared according to experimental conditions such as acid concentration and precipitation temperature. Neutralization processes were carried out in the concentration range of 5~37 wt% hydrochloric acid, 5~95 wt% sulfuric acid, and 5~85 wt% phosphoric acid, respectively. Precipitation temperatures in neutralization were controlled in the range of 293~333 K. Higher values of the distilled glycerol content were obtained due to the salt removal in the pretreatment case of neutralization with 10 wt% sulfuric acid and precipitation of 313 K with 85 wt% phosphoric acid, respectively. The variations of acid concentration and precipitation temperature in pretreatment steps affected to some extent glycerol recovery from the biodiesel byproduct.

• Polymer(Korea)
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• v.31 no.3
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• pp.184-188
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• 2007

Monodisperse PMMA/HDDA polymer particles were coated via electroless Ni plating using sodium hypophosphite as a reducing agent in an acidic environment. In this study, the effects of 1) the pretreatment conditions, 2) the plating temperature, 3) the plating pH, and 4) the initial pH, control of plating bath on the variation of plating rate, surface state of plated particles and plating reproducibility were investigated. It was observed that every pretreatment steps, especially conditioning and acceleration step, were very important for obtaining uniform Ni plating and the plating rate was increased with the increase of plating temperature and pH. Moreover, the initial pH control of plating bath was critical for the plating reproducibility.

• Journal of the Korean Wood Science and Technology
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• v.47 no.4
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• pp.418-424
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• 2019

Densification is a process for improving the strength properties of wood from the felling of young trees, which is a common harvest practice in community forests. A series of experiments was conducted to refine the process with particular regard to the determination of suitable pretreatment and treatment conditions. Samples of pine and gmelina measuring $23cm(L){\times}20cm(W){\times}2cm(T)$ underwent pretreatment through immersion in a 1:1 $CH_3COOH-H_2O_2$ solution at concentrations of 15%, 20%, and 30%. Samples pretreated with the 20% solution showed the greatest improvement in strength; further experiments were conducted to determine the optimum treatment conditions in terms of temperature and duration following immersion. Test samples with the same dimensions as those in the pretreatment experiment were soaked in a 1:1 20% $CH_3COOH-H_2O_2$ solution and warmed in a water bath. The test samples were then individually hot pressed to the target thickness, which was 30% less than the original thickness and held at $150^{\circ}C$ or $170^{\circ}C$ for 15 or 30 minutes. The treated samples were cut for an analysis of their density, recovery of set, and bending strength. Pine and gmelina exhibited the best characteristics after treatment at $150^{\circ}C$ for 30 and 15 minutes, respectively. The results suggest that the modified densification process had increased the bending strength of the wood, but the temperature and duration of treatment must be carefully considered for different wood species.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.18-24
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• 2012

Lignocellulose is difficult to hydrolyze due to the presence of lignin and the technology developed for cellulose fermentation to ethanol is not yet economically viable. However, recent advances in the extremely new field of biotechnology for the ethanol production are making it possible to use of Agriculture residual biomass, e.q., Barley straw, because of their several superior aspects as Agriculture residual biomass; low lignin, high contents of carbohydrates. Barley straw consists of 39.78% cellulose (glucose), 22.56% hemicelluloses and 19.27% lignin. Pretreatment of barley straw using NaOH pretreatment solutions concentration with 2%, temperature $85^{\circ}C$ and reaction times 1 hr were investigates. $NH_4OH$ pretreatment condition was solutions concentration with 15%, temperature $60^{\circ}C$, and reaction times 24hr were investigates. Furthermore, enzymatic saccharification using cellulose at $50^{\circ}C$, pH 4.8, 180 rpm for conversion of cellulose contained in barley straw to monomeric sugar. The pretreatment of barley straw using NaOH and $NH_4OH$ can significantly improve enzymatic saccharification of barley straw by extract more lignin and increasing its accessibility to hydrolytic enzymes. The result showed NaOH pretreatment extracted yield of lignin was 24.15%. $NH_4OH$ pretreatment extracted yield of lignin was 29.09%. Shaccharification of barley straw pretreatment by NaOH for 72hr and pH 4.8 result in maximum glucose concentration 15.39g/L (58.40%) and by $NH_4OH$ for 72hr and pH 4.8 result in maximum glucose concentration 16.01g/L (64.78%).

• Journal of the Korean Wood Science and Technology
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• v.43 no.3
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• pp.344-354
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• 2015

To investigate the effects of ionic liquid pretreatment on biomass, giant miscanthus was treated with 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) and 1-butyl-3-methylimidazolium acetate ([Bmim][OAc]) at three temperature conditions ($90^{\circ}C$, $110^{\circ}C$, and $130^{\circ}C$). As temperature condition increased, yield of the cellulose-rich product (CP) was reduced from 87.2% to 67.6%, while yield of the ionic liquid lignin (ILL) increased from 2.2% to 9.9%. Compared to the ILL, CP had lower carbon contents and higher oxygen contents. Enzymatic hydrolysis of CPs showed that conversion ratio of CP treated with [Emim][OAc] at $110^{\circ}C$ was 56.7%, the highest digestibility. Thermogravimetric analysis indicated that the maximum degradation rate decreased as temperature condition increased. In addition, maximum degradation temperature of ILL treated with [Emim][OAc] ranged from 274 to $279^{\circ}C$ which was lower than that of ILL treated with [Bmim][OAc]. Analytical date for ${\beta}$-O-4 linkage frequency in the ILL revealed that ${\beta}$-O-4 linkage frequency in the ILL decreased as the temperature rose. Furthermore, the highest S/G ratio of the ILL was determined to ca. 1.2 obtained from [Bmim][OAc] treatment at $110^{\circ}C$.

• Journal of the Korean Wood Science and Technology
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• v.44 no.1
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• pp.85-95
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• 2016

In this study, furfural, which is one of the value-added chemicals, was produced from the hydrolyzate of Quercus mongolica using dilute acid pretreatment, and the optimal pretreatment condition was determined by Response Surface Methodology (RSM) to obtain high yield of furfural. Based on Central Composite Design, the pretreatment experiment was designed with parameters such as reaction temperature ($X_1$), acid concentration ($X_2$), and reaction time ($X_3$) as independent variables, while dependent variable was furfural concentration (Y), and furfural yield (Z) was shown as percentage of Y per a dry weight basis. According to results of RSM, it was confirmed that reaction temperature ($X_1$) was the most influence factor and reaction temperature ($X_1$)-acid concentration ($X_2$) was the most significant interaction factor on furfural yield. Also, the optimal condition for the highest furfural yield was predicted at reaction temperature of $184^{\circ}C$, acid concentration of 1.17%, and reaction time of 5 min by RSM, and expected maximum yield of furfural was 6.37%. Experimentally, the maximum yield of furfural produced at above optimal condition was 6.21%, and it was considerably similar with the predicted value, and therefore the model for furfural production from the hydrolyzate of Quercus mongolica during dilute acid pretreatment could be built using RSM.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1254-1257
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• 2004

Comparative study on the effects of $H_2$ vs. $O_2$ plasma pretreatment of gate oxide on the degradation phenomenon of p-channel low-temperature polysilicon (LTPS) thin-film transistors (TFTs) were performed. After high drain current stress (HDCS) with $V_{gs}$ = $V_{ds}$, the p-channel TFTs pretreated by $O_2$ plasma showed increased immunity to the degradation of device characteristics such as threshold voltage and maximum field effect mobility because of the higher binding energy of Si-O bond than that of Si-H bond. The investigation of degradation phenomenon of these parameters with the applied power suggests that self-heating can be the major cause of degradation of polysilicon TFTs.