• KSBB Journal
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• v.28 no.1
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• pp.48-53
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• 2013

Pretreatment of wastepaper using aqueous glycerol was investigated to enhance the enzymatic hydrolysis. The effects of four factors (solid/liquid ratio, glycerol concentration, acid concentration, and reaction time) on the dissolution yield, the removal of cellulose, hemicellulose and lignin, and the enzymatic digestibility were examined at $150^{\circ}C$. The 1/8 of solid/liquid was determined to perform the reaction uniformly, and the 93% of glycerol concentration was found to be a minimum concentration to conduct the reaction under atmospheric pressure. Also, it was found that the acid concentration and reaction time were strongly related to the dissolution yield and the removal of cellulose, hemicellulose and lignin, but moderately to the enzymatic digestibility. At an optimum condition of $150^{\circ}C$, 1 h and 1% acid concentration, 56% and 49% of hemicellulose and lignin, respectively, were removed, while only 4% of cellulose was removed. The enzymatic digestibility at this condition was 86%, meaning that 83% of the glucan present in the initial substrate was converted to glucose. Compared to glycerol with ethylene glycol as a pretreatment solvent, glycerol is much cheaper than ethylene glycol, but ethylene glycol is superior to glycerol in delignification.

• Korean Chemical Engineering Research
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• v.53 no.4
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• pp.478-481
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• 2015

In this study, the hydrolysis of green macro-algae Enteromorpha intestinalis using solid acid catalyst was conducted to obtain total reducing sugar. The hydrolysis was optimized with four reaction parameters of liquid-to-solid (L/S) ratio, catalyst amount, reaction temperature, and reaction time. As a optimized result, the highest TRS of 7.74 g/L was obtained under condition of 7.5 L/S ratio, $140^{\circ}C$, 15% catalyst amount and 2 hr. By the way, at this condition, only 0.13 g/L 5-HMF was detected. The solid acid-catalyzed hydrolysis of marine resources had the potential in the field of bioenergy.

• Journal of ILASS-Korea
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• v.16 no.3
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• pp.126-133
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• 2011

In HCCI Engine, combustion is affected by change of compression speed corresponding to engine speed. The purpose of this study is to investigate the mechanism of influence of engine speed on HCCI combustion characteristics by using numerical analysis. At first, the influence of engine speed was shown. And then, in order to clarify the mechanism of influence of engine speed, results of kinetics computations were analyzed to investigate the elementary reaction path for heat release at transient temperatures by using contribution matrix. In results, as engine speed increased, in-cylinder gas temperature and pressure at ignition start increased. And ignition start timing was retarded and combustion duration was lengthened on crank angle basis. On time basis, ignition start timing was advanced and combustion duration was shortened. High engine speed showed higher robustness to change of initial temperature than low engine speed. Because of its high robustness, selecting high engine speed was efficient for keeping stable operation in real engine which include variation of initial temperature by various factors. The variation of engine speed did not change the reaction path. But, as engine speed increased, the temperature that each elementary reaction would be active became high and reaction speed quicken. Rising the in-cylinder gas temperature of combustion start was caused by these gaps of temperature.

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.61-65
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• 2018

In this study, the conversion of glucosamine, which is a major monomer in chitin/chitosan of crustacean shell, using solid acid catalyst was performed to obtain chemical intermediates such as levulinic acid and 5-hydroxymethyl furfural (5-HMF). The conversion reaction was optimized with four reaction factors of selection of ionic resin catalyst, reaction temperature, catalyst amount, and reaction time. As an optimized result, the highest levulinic acid yield was achieved approximately 36.86% under the determined conditions (Amberlyst 15 as a solid-acid catalyst, $180^{\circ}C$, 5% catalyst amount and 60 min). On the other hand, 5-HMF yield was found to be 0.91% at the condition.

• Journal of Environmental Health Sciences
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• v.26 no.4
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• pp.122-128
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• 2000

This study was carried out to survey trihalomethane formation potential(THMFP) levels in drinking underground water and to examine its characteristics in Kunsan area. In drinking underground water, THMFP increased with the lapse of reaction time and 96hr-THMFP was the highest of THMFPs examined. In many cases, 24hr-THMFP, 48hr-THMFP and 96hr-THMFP reflected 2hr-THMFP level due to the largest composition ratio of CHCl$_3$ decreased with the lapse of reaction of CHCl$_3$ among THM individuals. CHCl$_3$ was mostly formed within early 2hour of reaction time, but CHClBr$_2$ and CHBr$_3$ continued their formation until 48 hour. Accordingly, the composition ratio of CHCl$_3$ decreased with the lapse of reaction time while that of total Br derivatives increased. 96hr-THMFPs of drinking underground water in Kunsan area ranged from N.D.(not detected)~98.80 $\mu\textrm{g}$/$\ell$ and, in general, those of western section of Kunsan area, closer to the coast, showed the higher tendency. But, from their large range of variance, it could be considered that THMFPs differ individually even in the same section depending on such factors as the difference of water stream, circumstances of management and so on. All the parameters for water quality examined(pH, KMnO$_4$ consumption;UV$_{254}$ , TOC. Cl$^{[-10]}$ ) showed very week corelation with 96h-THMFP.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.4
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• pp.419-424
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• 2012

Purpose: We were to obtain the basic data for studying kinetic visual acuity through the comparative analysis in kinetic visual acuity, visual acuity, refractive error, pupil size, and hand reaction time for college students. Methods: We had tested the kinetic visual acuity, visual acuity, refractive error and hand reaction time using the kinetic visual acuity tester (KOWA AS-4A), the hand reaction time program and auto-refractometer for thirty-nine male and same female optometry students with more than +0.1 LogMAR visual acuity in both eyes. And the results were examined gender differences of kinetic visual acuity and the factors correlation. Results: In the measured values of male, pupil size were 6.00 mm, hand reaction time 0.23 msec, refractive error -1.66 D, visual acuity -0.07, kinetic visual acuity 0.59 and pupil size 5.86 mm, hand reaction time 0.24 msec, refractive error -2.08 D, visual acuity -0.02, kinetic visual acuity 0.46 in female. It was significant difference for kinetic visual acuity values but other factors were not. The kinetic visual acuity and left visual acuity had the highest correlation, r=-0.406. The kinetic visual acuity indicated more excellent values in the case of increasing visual acuity and decreasing myopia amount. Conclusions: It was able to see that male college students were better than female for kinetic visual acuity and the visual acuity were related to kinetic visual acuity.

• Economic and Environmental Geology
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• v.42 no.5
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• pp.395-401
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• 2009

The smectite-illite (SI) reaction is a ubiquitous process in siliciclastic sedimentary environments. For the last 4 decades the importance of smectite to illite (S-I) reaction was described in research papers and reports, as the degree of the (S-I) reaction, termed "smectite illitization", is linked to the exploration of hydrocarbons, and geochemical/petrophysical indicators. The S-I transformation has been thought that the reaction, explained either by layer-by-layer mechanism in the solid state or dissolution/reprecipitation process, was entirely abiotic and to require burial, heat, and time to proceed, however few studies have taken into account the bacterial activity. Recent laboratory studies showed evidence suggesting that the structural ferric iron (Fe(III)) in clay minerals can be reduced by microbial activity and the role of microorganisms is to link organic matter oxidation to metal reduction, resulting in the S-I transformation. In abiotic systems, elevated temperatures are typically used in laboratory experiments to accelerate the smectite to illite reaction in order to compensate for a long geological time in nature. However, in biotic systems, bacteria may catalyze the reaction and elevated temperature or prolonged time may not be necessary. Despite the important role of microbe in S-I reaction, factors that control the reaction mechanism are not clearly addressed yet. This paper, therefore, overviews the current status of microbially mediated smectite-to-illite reaction studies and characterization techniques.

• Journal of the Korean Chemical Society
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• v.50 no.3
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• pp.247-255
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• 2006

The purpose of this study was to investigate the correlation between concepts on chemical reaction rates and concepts on chemical equilibrium in high school students. The subjects of the investigation consisted of 120 third grade students attending high school in K city of Kyunggi province. For this study, questionnaire relevant to the subject of chemical reaction rates and chemical equilibrium was developed and the answers were analyzed. As a result of the study, a large percentage of high school students answered questions on reaction rates correctly, but only a small percentage of the students could give explanations. Many high school students answered questions on the rates of forward reactions correctly, but not the questions on the rates of reverse reactions. For the concepts on chemical equilibrium, many high school students gave correct answers when faced with equilibrium questions that only required the understanding of one side of the reaction. But the students could not answer the questions requiring understanding of both forward and reverse reactions as well. Overall, there was a little high correlation between concepts on chemical reaction rates and concepts on chemical equilibrium in high school students. Especially, high school students with little understanding of reverse reaction rates did not understand that chemical equilibrium is a dynamic equilibrium. Also, high school students with little understanding of the collision mechanism regarding chemical reaction rates did not understand the effect of concentration and catalyst factors on chemical equilibrium. And the correlation between concepts on chemical reaction rates and concepts on chemical equilibrium related to concentration and catalyst factors was low. In conclusion, the formation of scientific concepts on chemical reactions rates can decrease misconceptions on chemical equilibrium. Also the teaching-learning method limited to one side of a reaction can cause difficulty in forming the concepts on chemical dynamic equilibrium. Therefore, the development of a teaching-learning method which covers both the forward and reverse reactions can be effective in helping students form the concepts on chemical equilibrium.

• Bulletin of Food Technology
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• v.15 no.4
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• pp.29-35
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• 2002

To prevent the incidence of type food allergies, removal of food allergens by excluding all foodstuffs containing the allergen(s) or disruption of allergen(s) using proteases has been employed. Though allergen- specific digestion with a protease worked well in the preparation of low allergenic goods, it is often difficult to destroy allergenicity without adversely affecting the nutritive value, taste and rheological properties of foods. In the present study, we represented that herbs component contained both allergy- enhancing and inhibiting factors, in addition to llergens. We also reported that herbal component such as epigallocatechingallate (EGCG) and epicatechingallate (ECG) is possible to be allergy- inhibiting factors, but the exact mechanism by which they alleviate allergic response is left to be clarifying. Document of allergy enhancing factors and enrichment of allergy inhibiting factors may provide a new approach to diminish allergenicity of various foodstufffs. Clarification of the allergic reaction modifying mechanism of food components and optimization of the intake of allergy modifying factor are necessary for decrement of allergenicity of conventional food and prevention of incidents of allergic response

• YAKHAK HOEJI
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• v.55 no.6
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• pp.500-509
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• 2011

This study was to identify factors influencing drug compliance based on the subjects' interview regarding community pharmacy utilization for 2 weeks, in 2005 KNHANES. Good compliance was regarded as important factors in improving the effectiveness and minimizing adverse drug reaction, resulting in reducing the medical costs. 83% of total 11,208 pharmacy visits in 7,066 subjects showed good compliance. Good satisfaction for pharmacist's medication counseling (OR=2.23, 95% CI 1.92-2.58), higher out-of-pocket money (OR=1.32, 95% CI 1.14-1.54), and users of prescription drugs than non-prescription (OR=2.21, 95% CI 1.91-2.57) drugs were significant factors for better compliance. Disease of nervous system and mental and behavioral disorders showed lower drug compliance.