• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.4711-4717
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• 2011

Formation of TiN films by PVD method and the DC and RF sputtering deposition method can be applied, the injected gas to generate plasma ionization rate of the film forming speed is slow away, anything to increase the adhesion between films limitations have. To improve this, to investigate the deposition and ion beam evaporation simultaneously IBAD(Ion beam assisted deposition) when used, Ion beam surface coating material prior to the survey because the surface cleaning effect of a large, high film adhesion can be obtained. In addition, the high vacuum and low temperature, high purity thin film of uniform thickness in the benefits is.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.6
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• pp.1051-1055
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• 2008

If ZnS receive electric energy, it can generate light. Thin film ELD has merits of excellent sight effect, solid state and easy fabrication but has problems of low emission density, high power loss and high operating voltage. Thin film deposited by electron beam evaporator has good uniformity of 6%. We fabricate excellent thin film ELD for solution of this problems. The thin film ELD made in this study has brightness of 650fL at yellow light and 350fL at green light.

• Membrane and Water Treatment
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• v.10 no.2
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• pp.127-137
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• 2019

The D2EHPA/TBP co-extractants immobilized PolyHIPE membrane can be used for the selective separation of Mn (II) from Co (II). By solvent-nonsolvent method, D2EHPA/TBP co-extractants can be effectively immobilized into PolyHIPE membrane. The pore structure of PolyHIPE membrane and the presence of TBP enhance the stability of immobilized co-extractants. The optimal operating conditions for the separation of Mn (II) and Co (II) are feeding phase at pH 5.5, sulfuric acid concentration in the stripping phase of about 50 g/L and stirring speed at 400 rpm. The D2EHPA/TBP co-extractants ratio of 5:1 shows synergetic effect on Mn/Co separation factor about 22.74. The removal rate and recovery rate of Mn (II) is about 98.4 and 97.1%, respectively, while for Co (II) the transport efficiency is insignificant. The kinetic study of Mn (II) transport shows that high initial flux, $J_f^o=80.1({\mu}mol/m^2s)$, and maxima stripping flux, $J_s^{max}=20.8({\mu}mol/m^2s)$, can be achieved with D2EHPA/TBP co-extractants immobilized PolyHIPE membrane. The stability and reusability study shows that the membrane can maintain a long term performance with high efficiency. High purity of Co (II) and Mn (II) can be recovered from the feeding phase and stripping phase, respectively.

• Journal of Powder Materials
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• v.25 no.6
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• pp.482-486
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• 2018

Despite numerous advances in the preparation and use of GaN, and many leading-edge applications in lighting technologies, the preparation of high-quality GaN powder remains a challenge. Ammonolytic preparations of polycrystalline GaN have been studied using various precursors, but all were time-consuming and required high temperatures. In this study, an efficient and low-temperature method to synthesize high-purity hexagonal GaN powder is developed using sub-micron $Ga_2O_3$ powder as a starting material. The sub-micron $Ga_2O_3$ powder was prepared by an ultrasonic spray pyrolysis process. The GaN powder is synthesized from the sub-micron $Ga_2O_3$ powder through a nitridation treatment in an $NH_3$ flow at $800^{\circ}C$. The characteristics of the synthesized powder are systematically examined by X-ray diffraction, scanning and transmission electron microscopy, and UV-vis spectrophotometer.

• Tribology and Lubricants
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• v.39 no.5
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• pp.212-215
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• 2023

Diaphragm compressors play a crucial role in safely compressing large volumes of high-purity hydrogen gas without contamination or leakage, thereby ensuring quality and reliability. Diaphragm compressors use a thin, flat, triple-layered diaphragm plate that is subjected to repetitive piston pressure for compression. They are usually made of metallic materials such as stainless steel or Inconel owing to their high-pressure resistance. However, since they are consumable components, they fail due to fatigue from repetitive pressure and vibration stress. This study aims to evaluate the scratch characteristics of diaphragms in operational environments by conducting tests on three different samples: Inconel 718, AISI 301, and Teflon-coated AISI 301. The Inconel 718 sample underwent a polishing process, the AISI 301 sample used raw material, and the Teflon coating was applied to the AISI 301 substrate at a thickness of 50 ㎛. To assess the scratch resistance, reciprocating motion friction tests were performed using a tribometer, utilizing 220 and 2000 grit sandpapers as the counter materials. The results of the friction tests suggested that the Teflon-coated sample exhibited the lowest initial friction coefficient and consistently maintained the lowest average friction coefficient (0.13 and 0.11 with 220 and 2000 grit, respectively) throughout the test. Moreover, the Teflon-coated diaphragm showed minimal wear patterns, indicating superior scratch resistance than the Inconel 718 and AISI 301 samples. These findings suggest that Teflon coatings may offer an effective solution for enhancing scratch resistance in diaphragms, thereby improving compressor performance in high-pressure hydrogen applications.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.1
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• pp.55-61
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• 2013

The recovery of Zr from Zircaloy-4 (Zry-4) cladding hulls using a chlorination method was demonstrated for complete conversion of Zr into $ZrCl_4$. A chlorination reaction was performed by reacting Zry-4 hulls for 8 h under a 70 cc/min $Cl_2$ + 70 cc/min Ar flow at $380^{\circ}C$. The initial weight of the reactant (51.7 g) decreased to 0.49 g after 8 h of operation, which is only 0.95wt% of the initial weight. The weight of the total reaction products was 121.7 g with a high Zr purity of 99.80wt%. Fe and Sn were identified as major (0.18wt%) and minor (0.02wt%) impurities of the reaction products, respectively. It was also shown that Zr exhibited a high recovery ratio of 96.95wt% with a relatively small experimental loss of 2.34wt%. Observation of the reaction residues revealed that the chlorination reaction was dominant along the longitudinal direction, and surface oxide layers remained as reaction residues. The high purity and recovery ratio of Zr proposed the feasibility of the chlorination technique as an effective hull waste treatment method.

• Analytical Science and Technology
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• v.18 no.1
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• pp.5-12
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• 2005

It has been established that soft error of high precision electronic circuits can be induced by alpha particles emitted from the naturally occurring radioactive impurities such as U, and Th. As the electronic circuits have recently become lower dimension and higher density, these alpha-particle emitting radioactive impurities have to be strictly controlled. The aim of this study is to develop of NAA (Neutron Activation Analysis) and gamma-spectrometry to improve the analytical sensitivity and precision of U and Th. A new NAA method has been established using the HTS (Hydrulic transfer system) irradiation facility which has been used to produce radioisotopes for industries and medicines instead of the PTS (pneumatic transfer system) irradiation facility which has been used in general NAA. When the ultratrace impurities have to be analyzed by NAA, background gamma-ray spectra induced from $^{222}Rn$ and its progenies in air is serious problem. This unstable background has been eliminated or stabilized by the use of a nitrogen purging system. Ultra trace amounts of U (0.1 ng/g) and Th (0.01 ng/g) in high purity silica used for EMC could be analyzed by the use of HTS-NAA and low background gamma-spectrometry.

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.369-378
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• 2017

Vascular endotherial growth factor (VEGF) is a potent mitogen that stimulates vascular permeability and angiogenesis and has a potential in therapeutic applications. An industrial production method that provides high yield as well as purity is needed. Researches for various factors of mild solubilization with combination of ubiquitin fusion protein to increase solubility were carried out as well as by changing pH and denaturant concentration. Usage of pET28-a bacteral expression vector in BL21 (DE3) host cell was capable of producing approximately 14 g/L VEGF fusion protein in 20L fermentor. A purification process consisting of four chromatography steps including refolding and digestion with UBP1 resulted in mild solublization under the conditions of 2M urea and pH 10.0 due to ubiquitin fusion tag protein that increases in solubility of target protein VEGF. High yield of refolding and dimerization could be obtained between two step Ni-affinity chromatography. Multimeric and misfolded proteins and endotoxin were removed by DEAE anion exchange chromatography. Final monomers were removed from dimers by gel filtration chromatography. Characterization analysis of purified dimeric VEGF was performed using SDS-PAGE and RP-HPLC with a purity of 97%.

• Membrane Journal
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• v.21 no.4
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• pp.367-376
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• 2011

Huge amount of $CH_4$ mixtures has been emitted from landfills and organic wastes via anaerobic digestion. The recovery of high purity $CH_4$ from these gases has two merits: reduction of green house gases and production of renewable fuels. Membrane technology based on polymeric materials can be used in this application. In this study, asymmetric gas separation hollow fiber membranes were fabricated to develop the membrane-based bio-gas purification process. Polyethersulfone (PES) was chosen as a polymer materials because of high $CO_2$ permeability of 3.4 barrer and $CO_2/CH_4$ selectivity of 50[1]. Acetone was used as a non-solvent additive because of its unique swelling power for PES and highly volatile character. The prepared PES hollow fiber showed excellent separation properties: 36 GPU of $CO_2$ permeance and 46 of $CO_2/CH_4$ selectivity at optimized preparation conditions: 9wt% acetone content, 10cm air-gap and 4wt% PDMS coating processes. With the PES hollow fiber membranes developed, mixed $CO_2/CH_4$ test was done by changing various operating conditions such as pressures and feed compositions to meet the highest recovery of CH4 with 95% purity. High $CH_4$ recovery of 58 wt% was observed at 10 atm feed pressure for the 50 vol% of $CO_2$ in $CO_2/CH_4$ mixture.

• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.812-825
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• 2019

Two dolomite samples mined from the different mines were calcined using a batch-type microwave kiln ($950/60min^{\circ}C$) to produce $CaO{\cdot}MgO$. The hydration of the $CaO{\cdot}MgO$ samples shows different reactivity. MgO was separated by reacting with a strong acid cation exchange resin using the reactivity of the hydration properties of light dolomite ($CaO{\cdot}MgO$). Calcium ($Ca-(R-SO_3)_2$) was separated from the prepared $CaO{\cdot}MgO$ by the cation exchange resin ($CaO{\cdot}MgO:R-SO_3H=1:12mass%$). High purity MgO (higher than 94 mass %) with unburned $CaCO_3$ (1~2 mass %) was obtained by the separation process. The separated MgO was heated at $950^{\circ}C$ for 60 minutes to afford high purity MgO with MgO content higher than 96%. And High-grade $CaCO_3$ was prepared from the reaction with calcium adsorbed resin ($Ca-(R-SO_3)_2$) and NaOH, $CO_2$ gas.