• Journal of the Korean Chemical Society
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• v.6 no.2
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• pp.158-161
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• 1962

Three kinds of acid clay are chosen as samples; sample-I is the Korean acid clay, Sample-II is prepared by heating the mixure of the Korean acid clay with 20% $H_2SO_4$ for 4 hrs., and the sample-III, the reference sample, is the Japanes acid clay supplied by Katayama Chem. Co.. 15 samples are prepared by heating them at temperatures of $100^{\circ}C$, $300^{\circ}C$, $500^{\circ}C$, $700^{\circ}C$, and $900^{\circ}C$ for 6 hrs. separately.The adsorption experiments are carried out on these samples using bromphenol blue water soln.(conc., 0.001%) as adsorbate. It is found that the degree of decoloration depends upon the temperature of thermal treatment, i.e., the higher the temperature the lower the degree of decoloration is. At any specified temperature of thermal treatment, the degree of decoloration is in following order: sample II>sample I>sample III.The X-ray photographs of the samples show that the intensities of a few specified lines decrease with increasing temperatures of thermal treatment.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.6
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• pp.367-370
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• 2002

Candida cylindracea lipase was immobilized by adsorption on acid washed glass beads. It was observed that protein loading of the support depends on the size of the particle, with smaller particle containing higher amount of protein per unit weight. Initial reaction rate linearly varied up to enzyme concentration of 17.25 U/mL. Amount of free fatty acids produced was linearly proportional up to the enzyme loading of 1650 $\mu$g/g of bead. Achievement of chemical equilibrium took longer time in the case of less protein loading. Degree of hydrolysis was found to decrease in second and third consecutive batch operations on repeated use of immobilized lipase.

• The Korean Journal of Pesticide Science
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• v.10 no.4
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• pp.279-288
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• 2006

Three different experiments were undertaken to investigate the runoff and erosion loss of diazinon and metolachlor from sloped-field by rainfall. The mobility of two pesticides and which phase they were transported by were examined in adsorption study, the influence of rainfall pattern and slope degree on the pesticide losses were evaluated in simulated rainfall study, and the pesticide losses from soybean field comparing with bare soil were measured in field lysimeter study. Freundlich adsorption parameter (K) ranged $1.6{\sim}2.0$ for metolachlor and $4.0{\sim}5.5$ for diazinon. The K values of pesticides by the desorption method were higher than those ones by the adsorption method. Another parameter (1/n) in Freundlich equation for the pesticides tested ranged $0.96{\sim}1.02$ by desorption method and $0.87{\sim}1.02$ by adsorption method. By the SSLRC's classification for pesticide mobility of diazinon and metolachlor were classified as moderately mobile ($75{\leq}Koc$ <500). Runoff and erosion losses of pesticides by three rainfall scenarios were $0.5{\sim}1.0%$ and $0.1{\sim}0.7%$ for metolachlor and $0.1{\sim}0.6%$ and $0.1{\sim}0.2%$ for diazinon. Distribution of pesticides in soil polite were investigated after the simulated rainfall events. Metolachlor was leached to $10{\sim}15$ cm soil layer and diazinon was leached to $5{\sim}10$ cm soil layer. Losses of each pesticide in the 30% of sloping degree treatment were $0.2{\sim}1.9$ times higher than those ones in the 10% of sloping degree treatment. Pesticide losses from a series of lysimeter plots in sloped land by rainfall ranged $1.0{\sim}3.1%$ for metolachlor and $0.23{\sim}0.50%$ for diazinon, and were $1/3{\sim}2.5$ times to the ones in the simulated rainfall study. The erosion rates of pesticides from soybean-plots were $21{\sim}75%$ lower than the ones from bare soil plots. The peak runoff concentration in soybean-plots and bare soil plots were $1{\sim}9{\mu}gL^{-1}$ and $3{\sim}16{\mu}gL^{-1}$ for diazinon, $7{\sim}31{\mu}gL^{-1}$ and $5{\sim}40{\mu}gL^{-1}$ for metolachlor, respectively.

• Journal of the Korean Chemical Society
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• v.22 no.6
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• pp.380-385
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• 1978

Adsorption isotherms of o-xylene on Spheron 6, a graphitized carbon black, are obtained at various temperatures using a quartz beam microbalance. BET plots are made to estimate the molecular area of o-xylene from these isotherms. On Spheron 6, the molecular area of o-xylene (m.p $-25^{\circ}C$) remains constant until the temperature is increased up to $-15^{\circ}C$, but increases abruptly between $-15^{\circ}C$ and $-14^{\circ}C$, and then again remains constant thereafter. These results are interpreted as implying that the adsorbed o-xylene molecules are flatly localized on Spheron 6 with compact packing below $-15^{\circ}C$ while they gain a rotational degree of freedom around the benzene ring at the higher temperature.

• Tribology and Lubricants
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• v.17 no.2
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• pp.109-115
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• 2001

The lubricating performance of 23 kinds of polyol ester base oils 〔POEs〕 having different branch shapes was investigated by using a four ball tribometer under boundary lubrication condition. All the polyol ester base oils used in this study were made up of polyhydric alcohols of two-four valence and normal or branched fatty acids of different carbon number. The wear characteristics of polyol ester base oils are different from those of mineral oil, strongly affected by the branch shapes of fatty acids in their molecles. In particular, the polyol ester base oils having normal fatty acids such as n-octanoic acid, n-nonanoic acid etc. show much better wear performance than POEs having branched fatty acids such as 2-ethylhexanoic acid, 3,5,5-trimethyl hexanoic acid, etc. As the carbon chain length of normal fatty acids, in case of POEs of normal fatty acids, is increased, their wear rate is decreased and, in case of POEs of branched fatty acids, as the degree of branch of branched fatty acids is decreased, their wear rate is decreased. All the wear results of polyol ester base oils could be reasonably explained by comparing cohesive ability among fatty acid molecules in adsorption film by fatty acids obtained as POEs were decomposed.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.4
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• pp.59-65
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• 2008

Electrochemical properties of pulp fiber could be modified by LbL(Layer-by-Layer) multilayering. Salt concentration and pH affect the conformation and ionization degree of polyelectrolyte. In this study, therefore, we intended to evaluate the effect of pH and salt concentration in polyelectrolyte multilayering on the electrochemical properties of pulp fiber. The pH of the stock was varied to 4, 7, and 10. Salt concentration was controlled at 0.001, 0.003, and 0.005 M of NaCl. Higher zeta potential was obtained when pulp fibers were multilayered at the condition of higher pH and higher salt concentration. The final zeta potential of pulp fiber after multilayering was dependent on the adsorption ratio of polyelectrolyte and the initial zeta potential of fibers.

• Journal of the Korean Applied Science and Technology
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• v.27 no.3
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• pp.282-289
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• 2010

In preparation of silica aerogel-based hybrid coating materials, the combination of hydrophobic aerogel with organic polar binder material is shown to be very limited due to dissimilar surface property between two materials. Accordingly, the surface modification of the aerogel would be required to obtain compatibilized hybrid coating sols with homogeneous dispersion. In this study, the surface of silica aerogel particles was modified by using both surfactant adsorption and heat treatment methods. Four types of surfactants with different molecular weights and HLB values were used to examine the effect of chain length and hydrophilicity. The surface property of the modified aerogel was evaluated in terms of visible observation for aerogel dispersion in water, water contact angle measurement, and FT-IR analysis. In surface modification using surfactants, the effects of surfactant type and content, and mixing time as process parameter on the degree of hydrophilicity for the modified aerogel. In addition, the temperature condition in modification process via heat treatment was revealed to be significant factor to prepare aerogel with highly hydrophilic property.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.68-69
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• 2020

Recently, the problem of air pollution is drawing attention as a social problem worldwide. Particularly, fine dust is the biggest issue among air pollutants, and it is analyzed that fine dust is generated from air pollutants such as burning fossil fuels such as petroleum or coal, or exhaust gases from automobiles. In addition, yellow dust originating from China adjacent to Korea flows into the Korean Peninsula in a western wind, causing the concentration of fine dust to deteriorate. Fine dust is a harmful substance to the human body such as asthma or respiratory disease, and awareness of the risk is also increasing to a degree designated as a primary carcinogen. In this study, as a method for improving the indoor air quality, the Properties of the matrix according to the mixing ratio of powdered activated carbon based on blast furnace slag are reviewed. The flexural strength and compressive strength were measured, and a fine dust concentration measurement experiment will be conducted later.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.1
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• pp.31-38
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• 2008

The primary objective of this study was to evaluate the variation of the molecular size distribution by granular activated carbon (GAC) adsorption. GAC adsorption was assessed by using the rapid small-scale column test (RSSCT) and high-performance size-exclusion chromatography (HPSEC) was used to analyze the molecular size distribution (MSD) in the effluent of GAC column. RSSCT study suggested that GAC adsorption exhibited excellent interrelationship between dissolved organic carbon (DOC) breakthrough and MSD as function of bed volumes passed. After GAC treatment, the nonadsorbable fraction which was about 25percents of influent DOC corresponded to the hydrophilic (HPI) natural organic carbon (NOM) of NOM fractions and was composed entirely of <300 molecular weight (MW) in the HPSEC at the initial stage of the RSSCT operation. The dominant MW fraction in the source water was 1,000~5,000daltons. At the bed volumes 2,500, MW <500 of GAC treated water was risen rather than it of source water. After the bed volumes 7,300 of operation, the MW 1,000~3,000 fraction was closed to about 80percents of DOC found in the GAC influent. The Number-average molecular weight (Mn) value determined using HPSEC for the effluent of GAC column was gently increased as DOC breakthrough progress. The quotient p(Mw/Mn) can be used to estimate the degree of polydispersity was shown greatest value for the GAC effluent at the initial stage of the RSSCT operation.

• Polymer(Korea)
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• v.30 no.4
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• pp.305-310
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• 2006

The hybrid cation exchange fibers using graft copolymer of styrene onto PE/PP with PET trunk polymers were synthesized by electron beam preirradiation. The degree of grafting showed 123% value at 80% concentration of styrene. And also, amount of sulfonyl group in the ion exchanger was showed 3.3 mmol/g at 70% concentration of styrene and their values were constant after 70%. The tensile strength for fibers was lower than trunk fibers, and their value of ion exchange fibers were also below than copolymer. It was $0.206kgf/mm^2$ value. The breakthrough time for Ca and Mg ions of hybrid cation exchange fibers were increased with the increase in the pH and temperature. The breakthrough of Mg was slower the mixture than single Mg solution. Adsorption rate constant for Ca, Mg ions and maximum ion exchange capacity were 0.012, 0.011 L/mg.h and 47.06, 42.83 mg/g, and also, activation energies were 2169 and 1534 J/mol, respectively.