• Journal of the Korean Electrochemical Society
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• v.21 no.4
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• pp.61-67
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• 2018

As emerging the new electric devices, the commercial lithium ion batteries have faced with various challenges. In this regard, many efforts to solve challenges have been tried. In order to solve the above problems in terms of development of a new secondary battery, we successfully demonstrated the two electrocatalysts, such as MCWB and PPY hydrogel, PPY hydrogel and MCWB showed typical H3-type BET isotherm, indicating that micro- and mesopores existed. Especially, in terms of voltage efficiency at the first cycle, PPY hydrogel was higher than that of MCWB, but lower than that of PtC. More interestingly, the PPY hygrogel based seawater battery exhibited charge-discharge reversibility during 20 cycles, and the voltage efficiencies ranged from 70.32 % to 77.35 % in cyclic performance test.

• Journal of the Korean Society for information Management
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• v.36 no.1
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• pp.73-94
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• 2019

The purpose of this study is to investigate the quality of service that affects satisfaction of special library users and to suggest ways to improve the function and role of special library. The data were collected by survey and interview method conducted with 111 library users in 6 local research institute using modified questionnaires based on LibQUAL+. The results revealed that human quality factor had more influence on library service satisfaction than space and information quality factor. Also, there were statistically significant influence between library service satisfaction and three sub service factors, such as service attitude, space convenience, and information usability. The interviewers indicated problems of special library service in lack of data, inactivation of digital data, space problem, data sharing problem, and lack of experts. Finally this study proposed several suggestions to improve service quality of special library of local autonomous entity research institution.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.12
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• pp.1013-1020
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• 2020

Spark-induced breakdown spectroscopy (SIBS) utilizes an electric spark to induce a strong plasma for collecting atomic emissions. This study analyses the potential for usinga compact SIBS instead of conventional laser-induced breakdown spectroscopy (LIBS) in discriminating rocks and soils for planetary missions. Targeting bulky solids using SIBS has not been successful in the past, and therefore a series of optimizations of electrode positioning and electrode materials were performed in this work. The limit of detection (LOD) was enhanced up to four times compared to when LIBS was used, showing a change from 78 to 20 ppm from LIBS to SIBS. Because of the higher energy of plasma generated, the signal intensity by SIBS was higher than LIBS in three orders of magnitude with the same spectrometer setup. Changing the electrode material and locating the optimum position of the electrodes were considered for optimizing the current SIBS setup being tested for samples of planetary origin.

• Applied Chemistry for Engineering
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• v.33 no.4
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• pp.343-351
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• 2022

Lithium-ion batteries (LIBs) are considered promising energy storage devices with good performance such as high energy density, slow self-discharge rate, high rate charge capacity, and long battery life. However, the application of these LIBs in the high-energy density electric vehicle and large device industries poses a major safety problem. In order to solve this problem, developing a material having high thermal stability and intrinsic safety is the ultimate solution for improving the stability and electrochemical performance of LIBs. This review introduced a surface modification technology of a separator to overcome the stability problem of a commercial separator, and summarized and summarized the research trends using the modified separator for a lithium-ion battery. Based on this, the future prospects for the separator development by surface modification were discussed.

• Journal of the Korean institute of surface engineering
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• v.57 no.1
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• pp.22-30
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• 2024

This study reports a direct growth of carbon nanotubes (CNTs) on the surface of LiCoO₂ (LCO) powders to apply as highly efficient cathode materials in lithium-ion batteries (LIB). The CNT synthesis was performed using a thermal chemical vapor deposition apparatus with temperatures from 575 to 625 ℃. Ferritin molecules as growth catalyst of CNTs were mixed in deionized (DI) water with various concentrations from 0.05 to 1.0 mg/mL. Then, the LCO powders was dissolved in the ferritin solution at a ratio of 1g/mL. To obtain catalytic iron nanoparticles on the LCO surface, the LCO-ferritin suspension was dropped in silicon dioxide substrates and calcined under air at 550℃. Subsequently, the direct growth of CNTs on LCO powders was performed using a mixture of acetylene (10 sccm) and hydrogen (100 sccm) for 10 min. The growth behavior was characterized by scanning and transmission electron microscopy, Raman scattering spectroscopy, X-ray diffraction, and thermogravimetric analysis. The optimized condition yielding high structural quality and amount of CNTs was 600 ℃ and 0.5 mg/mL. The obtained materials will be developed as cathode materials in LIB.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.257-258
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• 2009

Nanocomposites of a epoxy resin are synthesized and evaluated the present study investigated. The effect of nanoclay additives on the properties of diglycidyl ether or bisphenol A(DGEBA) epoxy resin. DGEBA was mixed with 3~7 wt% organically modified layered silicate, Cloisite 30B for three hours. The average grain size of the specimens decreased with adding Cloisite 30B. The dielectric constant showed between 3.2 ~ 3.5 and the dielectric loss showed between 3.2 ~ 5.7 % in all specimens.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.131-132
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• 2006

We experimentally demonstrated the synthesis of silicon nanoparticles by using high-density ablation plasma prepared by the interaction of an intense pulsed light-ion beam (LIB) with a target. known as the intense pulsed ion beam evaporation (IBE) method. Light emission was obtained from the silicon nanoparticles. It was determined that the ambient gas reaction is very important and useful method to obtain the photoluminescence from the silicon nanoparticles.

• Journal of the Korean Chemical Society
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• v.3 no.1
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• pp.31-35
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• 1954

Upon the basis of the results obtained hitherto in the studies of the stereochemical reaction mechanisms, the author has concluded that the stereospecificity of enzymes has essentially a relative character. And the author has pointed out the possibility of the occurrence of a new enzyme "inverskinase", which catalyses the reversible inversions such as D-compound ${\leftrighyarrow}$ L-compound in living organisms, and considered the stereospecificity of enzymes and the optical purity of components of living organism from this new standpoint.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.9
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• pp.140-146
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• 2001

Seals in a universal joint bearing are important components reinforcing lubrication performance by holding lubricant and preventing infiltration of dust, moisture, etc.. There is a great difference in seal performance according to seal shape and bonding position. Therefore, in this study, as for both the lip type seal and the O-ring type seal, FE analysis is conducted using Mooned-Rivlin Model. The results show that O-ring type seal does not have any effect of misalignment angle compared with lib type seal, which is more profitable.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.703-706
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• 2005

This study is analyzed mechanical properties and durability of pavement of a road permeability porous concrete to mix polymer for the enhance of porous concrete of performance and durability. As a result, void ratio showed the tendency which the mixing rate of polymer is decreased a little as increased. And, the influence of void ratio according to the kind of polymer has the difference, but void ratio showed the tendency which the mixing rate of polymer is decreased a little as increased. Compressive strength showed the tendency which the mixing rate of polymer is increased a little as increased. but, it showed the tendency to be reduced rather when above $20\%$ it mixed polymer mixing rate $10\%$ at apex.