• Journal of the Korean Chemical Society
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• v.40 no.2
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• pp.117-121
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• 1996

Two new crown ethers containing nitrogen and sulfur atoms adjacent to the crown rings were prepared. 4'-Benzothiazolylbenzo-12-crown-4 (1) or 4'-benzothiazolylbenzo-15-crown-5 (2) were synthesized by reaction of 2-aminothiophenol with 4'-formylbenzo-12-crown-4 (3) or 4'-formylbenzo-15-crown-5 (4) respectively. (3) and (4) were obtained by reaction of 3, 4-dihydroxybenzaldehyde with tri- or tetraethyleneglycol ditosylate. Triethyleneglycol ditosylate or tetraethyleneglycol ditosylate were synthesized by reaction of p-toluenesulfonylchloride with triethyleneglycol or tetraethyleneglycol in the presence of sodium hydroxide.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.5
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• pp.494-502
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• 2016

A 1-dimensional heterogeneous reactor model with the gas-solid interfacial phase gradients was developed for the simulation of the packed bed reactor where the exothermic reversible water gas shift reaction for the natural gas steam reformed gas was proceeding in adiabatic mode. Experimental results obtained over the WGS catalyst, C18-HA, were best simulated when the frequency factor of the reaction rate constant was adjusted to a half the value reported over another WGS catalyst, EX-2248, having the same kinds of active components as the C18-HA. For the reactor of the inside diameter 158.4 mm and the bed length 650 mm, the optimum feeding temperature of the reformed gas was simulated to be $194^{\circ}C$, giving the lowest CO content in the product gas by 1.68 mol% on the basis of dried gas. For reactors more extended in the bed length, the possible lowest CO content in the product gas with the optimum feeding temperature of the reformed gas were suggested.

• Journal of Electrochemical Science and Technology
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• v.12 no.2
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• pp.279-284
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• 2021

The high theoretical specific capacity of lithium-sulfur (Li-S) batteries makes them a more promising energy storage system than conventional lithium-ion batteries (LIBs). However, the slow kinetics of the electrochemical conversion reaction seriously hinders the utilization of Li-S as an active battery material and has prevented the successful application of Li-S cells. Therefore, exploration of alternatives that can overcome the sluggish electrochemical reaction is necessary to increase the performance of Li-S batteries. In this work, an ionic liquid (IL) is proposed as a functional additive to promote the electrochemical reactivity of the Li-S cell. The sluggish electrochemical reaction is mainly caused by precipitation of low-order polysulfide (l-PS) onto the positive electrode, so the IL is adopted as a solubilizer to remove the precipitated l-PS from the positive electrode to promote additional electron transfer reactions. The ILs effectively dissolve l-PS and greatly improve the electrochemical performance by allowing greater utilization of l-PS, which results in a higher initial specific capacity, together with a moderate retention rate. The results presented here confirmed that the use of an IL as an additive is quite effective at enhancing the overall performance of the Li-S cell and this understanding will enable the construction of highly efficient Li-S batteries.

• Clinical and Experimental Reproductive Medicine
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• v.27 no.2
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• pp.201-209
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• 2000

Objective: This study has been carried out to evaluation the effect of fertilization promoting peptide (FPP) on the kinematic parameters, capacitation and acrosome reaction of the frozen-thawed human spermatozoa. Methods: After FPP treatment, we examined kinematic parameters, capacitation and acrosome reaction, using the methods of computer-aided sperm analysis (CASA) and chlortetracycline (CTC) fluorescence analysis. Results: We have obtained the evidence that FPP can promote the capacitation and inhibit the spontaneous acrosome reaction of frozen-thawed human spermatozoa in vitro. FPP ($25{\sim}100$ nM) induced a significant increase in the proportion of B-pattem capacitated spermatozoa, and a significant decrease in the proportion of F-pattem uncapacitated ones without significant stimulation of acrosomal exocytosis. In the kinematic parameters treatment, FPP treated groups maint3ined higher LIN, BCF and STR than those of control. The VAP, VSL, VCL and ALH were not different. Therefore it is suggested that FPP in human seminal plasma may play a positive role in promoting human sperm function.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.1
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• pp.119-124
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• 2013

In this paper, we analysed fatty acid methyl ester contents in the biodiesel which is produced from the newly developed biodiesel production equipment. The lard oil was used as the raw material through various experimental conditions. Thirty one experiments were conducted, which were based on the experimental conditions that designed by central composite design method. The effects of four independent variables, including reaction temperature, reaction time, oil to methanol molar ratio, and catalytic amount, were investigated at five levels using central composite design (CCD). Fatty acid methyl ester content was chosen dependent variable. Although the results of analysis of the surface with an irregular surface geometry showed that the biodiesel was partially impure after the reaction due to the natural characteristics of the lard oil as the raw material, we could confirm the relationship between them from the facts that the production amount of fatty acid methyl ester changes according to reaction temperature, reaction time, oil to methanol molar ratio, and catalytic amount.

• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.409-414
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• 2012

Xanthorrhizol is a bisabolane type of natural sesquiterpene, the major component of essential oils of Curcuma xanthorrhiza. 2-(3-Methoxy-4-methylphenyl)propan-1-ol and 2-(3-hydroxy-4-methyl phenyl)propan-1-ol could be essential building block for enantioselective synthesis of xanthorrhizol. Enantioselective (c = 53%, E = $80{\pm}3$) for R-(+)-2-(3-hydroxy-4-methylphenyl) propan-1-ol and (c = 58%, E = $27{\pm}1$) for R-(+)-2-(3-methoxy-4-methylphenyl) propan-1-ol resolution processes were developed via lipase-catalyzed reaction. We found lipase Aspergillus oryzae (AOL) and Porcine pancreas (PPL) are selective to transesterification and hydrolysis in organic and aqueous phase. Modified demethylated substrate is appropriate for enantioselective hydrolysis reaction without any additives. Enantiopure chiral alcohol was crystallized from ethyl acetate/n-hexane co-solvent system. Gram scale resolved chiral intermediate will facilitate the synthesis of the unnatural S-(+)-xanthorrhizol, the corresponding isomer of the natural one.

• Bulletin of the Korean Chemical Society
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• v.29 no.6
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• pp.1224-1228
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• 2008

The reaction of internal diynes and cyclopentadiene in the presence of 5 mol % of cobalt catalysts proceeded under 5 atm of carbon monoxide pressure to give a high yield of the corresponding [2+2+2] cycloaddition product. By lowering carbon monoxide pressure from 30 atm to 5atm, cyclopentadiene can be used as a dienophile in the cobalt carbonyl-catalyzed [2+2+2] cycloaddition reaction between internal diynes and cyclopentadiene.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.454-460
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• 1998

The vibration behavior of fuel rods has been analyzed by FEM in consideration of axial force and support spring constants. The axial compression force on the fuel rod in reactor decreases with the fuel rod burnup, and its decrease makes the natural frequencies of fuel rod considerably increase. The change of support spring constant can contribute to the remarkable change of the mode shapes, but not greatly to the natural frequencies. The reaction forces of support springs are obtained from normalizing the lst mode with the max. 0.2 mm displacement. The calculated reaction forces are larger than the previous results obtained by disregarding the deflections of the support springs.

• YAKHAK HOEJI
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• v.46 no.1
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• pp.52-57
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• 2002

Effects of the butanl fraction of Astragali Radix (BFAR) on the cellular and nonspecific immune responses were investigated in ICR mice. Mice were divided into 4 groups and BFAR at doses of 5, 25 and 125 mg/kg u ere administered orally to mice daily for 3 weeks, and the normal animals were given vehicle. The results of this study are summarized as follows; the relative weight of thymus was greatly increased by BFAR treatment, compared with that in mormal mice. However, the body weight gain was not affected. Delayed-type hypersensitivity (DTH) reaction to sheep red blood cells (SRBC) for cellular immunity was significantly enhanced by BFAR treatment, compared with those in normal mice. In these mice, BFAR also dose-dependently increased activities of phagocyte and natural killer (NK) cells as well as the number of leukocyte resulted from nonspecific immunity Thus, these results demonstrate that BFAF treatment results in a significant increase in both cellular and nonspecific immune responses to antigen in concentrations that enhance humoral immune function.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.10
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• pp.1248-1253
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• 1999

This study is concerned about the combustion characteristics of methane-air and methane/hydrogen-air mainly the behavior of burning velocity including the effect of the ignition energy. The experiments were conducted in a spherical combustion bomb designed in this laboratory. The burning velocities were measured by the pressure-time history and the reaction rates were estimated theoretically. The experimental results showed that the burning velocity increased by 25 to 50 percent when hydrogen is added to methane by 20 percent.