• Korean Journal of Food Science and Technology
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• v.20 no.4
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• pp.547-552
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• 1988

Aminoacylase immobilized on chitosan was applied for optical resolution of DL-amino acids. Optimun pH's for hydrolysis of N-ac DL Met, N-ac DL Try and N-ac DL Phe by immobilized aminoacylase were 8.0, 7.0, and 7.5, respectively. The pH stability of immobilized aminoacylase was less than that of soluble enzyme, while there was no difference in thermostability between immibilized and soluble enzymes. The reaction rate of immobilized enzyme was maximum, when concentrations of N-ac DL Met, N-ac DL Try and N-ac DL Phe were 0.05, 0.03 and 0.05M, respectively. Continuous resolution of M/20 N-ac DL amino acids with immobilized aminoacylase packed in a column resulted in 100% hydrolysis upto space velocity $2.0\;at\;45^{\circ}C$, and the half-life of the column at space velocity 5.0 was about 25 days. The yield of L-Met, L-Try and L-Phe recovered from 2 liter of column effluent were 57%, 52% and 52%, respectively.

• Journal of Electrochemical Science and Technology
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• v.10 no.4
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• pp.387-393
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• 2019

Activated carbons (ACs) are considered important electrode materials for supercapacitors because their large specific surface areas lead to high charging capacities. In the conventional synthesis of ACs, a substantial amount of carbon is lost during carbonization of a precursor. The development of a method to synthesize ACs in high yield would lower their manufacturing cost. Here, we demonstrate the synthesis of high-specific-surface-area NaOH-AC from carbon prepared via a hydrothermal carbonization (HTC) route, with a higher yield than that achieved through conventional pyrolysis carbonization. The amorphous carbon was derived from HTC of sugar and subsequently activated at 800℃ with various NaOH etchant/C ratios under a N₂ atmosphere. The AC prepared at 4:1 NaOH/C exhibited the highest surface area (as high as 2,918 ㎡ g^-1) and the highest specific capacitance (157 F g^-1 in 1 M aqueous Na₂SO₄ electrolyte solution) among the NaOH-AC samples prepared in this work. On the basis of their high specific capacitance, the NaOH-ACs prepared from HTC sugar are suitable for use as electrode materials for supercapacitors.

• Journal of environmental and Sanitary engineering
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• v.17 no.3
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• pp.99-109
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• 2002

Charcoal $tube/CS_2$ method are more popularly used than any other in the measurement of the working environment for the exposure evaluation of organic solvent, but it is some weak points that the lower accuracy can be obtained on the polar materials and within the range of the low concentration. Thus solvent desorption method has been developed to make accuracy higher and to overcome some weak points. However, because of high price of adsorption tube for thermal desorption and the short of study on its application to the working environment, it is not popularly used in the domestic industrial hygiene fields. This dissertation aims to develop thermal desorption and adsorption tubes for measuring organic solvents in the working environment, by comparing and analyzing breakthrough condition and adsorption capacity with ACF. Specific surface area of ACF used in this study is wider than the one of AC and micropore of ACF related with adsorption has been developed, and adsorption velocity and adsorption amount are very excellent by linking a pore of surface and an inside well into micropore. 1. Result of analysis on physical characteristics of adsorbent, the specific surface area of ACF was 1.3 times higher than that of AC. Distribution ratio of micropore related to adsorption was 94% on ACF and AC. Result of SEM, micropore of the AC is opened to the surface. In contrast, ACF shows that extremely fast adsorption speed. Because of micropore are exposed on the surface and penetrate through each other. 2. Breakthrough characteristics of adsorbents was not different from slop of breakthrough curve. The effluent concentration reaches 10% of initial concentration($C_{out}/C_{in}=0.1$, break point) of ACF was 30~316min longer than that of AC. Therefore, the adsorption capacities of ACF was 1.1~4.6 times higher than that of AC. ACF can be used as a proper adsorbent for measurement of organic solvent.

• Journal of Microbiology and Biotechnology
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• v.15 no.6
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• pp.1178-1182
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• 2005

Survival of thermotolerant Lactobacillus reuteri KUB-AC5 in $20\%$ (w/v) skim milk was found to be $11.3\%$ after spray drying by using a pilot scale spray dryer with inlet temperature at $170^{\circ}C$ and outlet temperature at $85^{\circ}C$. The ability of dried cell to produce antimicrobial activity was not affected by the spray drying. The model system for predicting viability of spray-dried L. reuteri KUB-AC5 during long-term storage was established, based on the Arrhenius equation, and verified by experimental data, because the viability of cells during storage can be correlated with storage temperature. The viability during storage at $30^{\circ}C$ declined more rapidly than that storage at $4^{\circ}C$.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.6
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• pp.171-177
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• 2002

Metal matrix composites had generated a lot of interest in recent times because of significant in specific properties, it was also highlighted as the material of frontier industry because strength, heat-resistant, corrosion-resistant and wear-resistant were superiored. In recent years, the study of metal matrix composite has increased by aluminum alloy. The study is based on the tribological properties of AC4CH that is a part of the mechanical property of metal matrix composites. Metal matrix composite that is produced from matrix material AC4CH and reinforcement SiO$_2$, Al$_2$O$_3$ and TiO$_2$ are added to the metal matrix composite fur strength so binding among the whisker can take place. Each metal matrix composite is produced using the squeeze casting method. To test for tribe a pin-on-disk machine and lubricant is used without paraffine 8.2CST at room temperature which is 40$\^{C}$. As the results of this study, the tribological properties of each specimen are more improved than AC4CH. The variation of coefficient resistance is more stable at the AC4CH and TiO$_2$, but the variation rates are higher at the inanimate binder.

• Journal of the Korean Society of Tobacco Science
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• v.23 no.2
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• pp.133-140
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• 2001

PAP-I cDNA was synthesized from total RNA of Phytolacca americana leaves by RT-PCR, and then subcloned to recombinant vector pBluescript II SK-. Using PCR with primers designed in our laboratory, we could get the 9 deletion mutant PAP-I cDNA fragments. The first of the fragments was deleted by 66bp from immature N-terminal and then the rest were deleted by 90bp sequentially. Sequentially deletion mutant PAP-I cDNAs were inserted to pAc55M, on down-stream of gall promoter. Recombinant pAc55M was transformed to yeast cells, psy1 and the cells were spreaded on SC_urn-/glucose plate media. Colonies on SC_ura-/glucose plate were streaked on the same position of SC_ura-/glucose and SC_ura-/galactose plate, and we selected colonies growing on both plates, which carry non-cytotoxic deleted mutant PAP-I cDNA. We selected 4 deletion mutant PAP-I cDNAs which have not cytotoxicity.

• Carbon letters
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• v.15 no.1
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• pp.45-49
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• 2014

In this study, synthetic viscose rayon fabric has been used for preparing activated carbon fabric (ACF), impregnated with different concentrations of $H_3PO_4$. The effect of $H_3PO_4$ impregnation on the weight yield, surface area, pore volume, chemical composition and morphology of ACF were studied. Experimental results revealed that both Brunauer-Emmett-Teller surface area and micropore volume increased with increasing $H_3PO_4$ concentration; however, the weight yield and microporosity (%) decreased. It was observed that samples impregnated at $70^{\circ}C$ (AC-70) give higher yield and higher microporosity as compared to $30^{\circ}C$ (AC-30). The average pore size of the ACF also gradually increases from 18.2 to 19 and 16.7 to $20.4{\AA}$ for $30^{\circ}C$ and $70^{\circ}C$, respectively. The pore size distribution of ACF was also studied. It is also concluded that the final ACF strength is dependent on the concentration of impregnant.

• Progress in Superconductivity
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• v.13 no.2
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• pp.111-116
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• 2011

Since superconducting wires have no resistance, electromagnets based on the superconducting wires produce no resistive heating with DC current as long as the current does not exceed the critical current of the wire. However, unlike resistive wires, superconducting wires exhibit AC heat loss. Embedding fine superconducting filaments inside copper matrix can reduce this AC loss to an acceptable level and opens the way to AC-capable superconducting coils. Here, we introduce an easy and accurate method to measure AC heat loss from sample superconducting coils by measuring changes in the rate of gas helium outflow from the liquid helium dewar in which the sample coil is placed. This method provides accurate information on total heat loss of a superconducting coil without any size limit, as long as the coil can fit inside the liquid helium dewar. With this method, we have evaluated AC heat loss of two superconducting solenoids, a 180-turn solid NbTi wire with 0.127 mm diameter (NbTi coil) and a 100-turn filamented wire with 1.4 mm diameter where 7 NbTi filaments were embedded in a copper matrix with copper to NbTi ratio of 6.7:1 (NbTi-Cu coil). Both coils were wound on 15 mm-diameter G-10 epoxy tubes. The AC heat losses of the NbTi and NbTi-Cu coils were evaluated as $53{\pm}4.7\;{\mu}W/A^2Hzcm^3$ and $0.67{\pm}0.16\;{\mu}W/A^2Hzcm^3$, respectively.

• Korean Journal of Food Science and Technology
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• v.10 no.2
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• pp.237-244
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• 1978

Among the strains isolated form the various sources, the strain AC-12 producing a powerful pectinase was selected by the extensive screening test. The selected strain was indentified and its toxicity investigated. The conditions of the pectinase production, the characteristics of the purified enzyme and the clarification effect on the apple juice were studied. 1. The selected strain AC-12 was identified by the classification method of paper and fennel and named as Aspergillus sp. AC-12. 2. As a result of the breeding test of the white mouse, no toxicity was found from this enzyme. 3. The yield of pectinase in the medium of defatted rice bran was much better than that in the medium of wheat bran. 4. The optimum conditions for the culture of the strain in the medium of defatted rice bran were that the cultural time was 72hrs, the amount of water to be added about 80%, temperature $30{\sim}35^{\circ}C$ and pH $3.0{\sim}5.0$. 5. The yield of pectinase was slightly increased by the addition of pectin to the medium of defatted rice bran and by the addition of pectin, $NaNO_3$ and $K_2HPO_4$ to the medium of wheat bran, respectively. 6. The optimum conditions for the enzyme activity were pH $3.0{\sim}4.0$ and temperature $40{\sim}50^{\circ}C$. The enzyme was stable below $40^{\circ}C$ and pH $2.0{\sim}8.0$, respectively. But above $50^{\circ}C,$ this enzyme was abruptly inactivated. The activity was slightly increased by the addition of $MnSO_4\;and\;CuSO_4.$ 7. It was regarded that the opimum temperature for the clarification of the apple juice was $40{\sim}50^{\circ}C$, the optimum pH 3.0 and the optimun concentration of the enzyme 0.1%, and the apple juice was almost clarified by the reaction at $45^{\circ}C$ for 60 minutes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.203-204
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• 2006

Nano-Varistors fabricated with ZnO 30nm and 80nm powders were studied about the electrical characteristics with AC accelerated degradation in this paper Especially, ZnO nano-powder varistors were sintered m air at $1050^{\circ}C$ and analyzed the phenomenons of before and after AC degradation test. The stress conditions of AC degradation test were $1.0V_{1mA}$ $115{\pm}2^{\circ}C$ for 24h. 80nm-varistor was exhibited better performance than 30nm-varistor m the electrical stabilities. And then 80nm-varistor resulted m the degradation characteristics that the variation rate of operating voltage, nonlinear coefficient and leakage current was -0 3%, -0 4% and -3 3%, respectively.