• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.120.1-120.1
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• 2015

We investigate the degradation pattern of Black phosphorus (BP) field effect transistor (FETs) investigated by using an mechanically exfoliated BP that react O2 and water vapor in ambient condition, degradation. The BP FETs was electrically measured every 20 minutes (1cycle) in the air, the total cycle is 100. We show electrical changes with Mobility, On/off ratio, Current and a significant positive shift in the threshold voltage. We extracted the current level at Vgs-Vth = 0, -10, -20 and fitting with Swiss-cheese model. This model suggested that Swiss-cheese model is well fitted with degradation pattern of BP FETs.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.186-186
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• 2015

We have introduced multifunctional ITO single thin films formed by normal sputtering system equipped with a plasma limiter which effectively blocks the bombardment of energetic negative oxygen ions. MFSS ITO also possesses high gas diffusion barrier properties simultaneously low resistivity even it deposited at room temperature without post annealing on plastic substrate. Nano-crystalline enhancement by Ar energy has energy window from 20 to 30 eV under blocking NOI condition. Effect of blocking NOI and optimal Ar energy window enhancement facilitate that resistivity is minimized to $3.61{\times}10^{-4}{\Omega}cm$ and the WVTR of 100 nm thick MFSS ITO is $3.9{\times}10^{-3}g/(m^2day)$ which is measured under environmental conditions of 90% relative humidity and 50oC that corresponds to a value of ${\sim}10^{-5}g/(m^2day)$ at room temperature. The multifunctional MFSS ITO with low resistivity, and low gas permeability will be highly valuable for plastic electronics applications.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.167.1-167.1
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• 2015

We investigate the degradation pattern of Black phosphorus (BP) field effect transistor (FETs) was investigated by using an mechanically exfoliated BP that react O2 and water vapor in ambient condition, degradation. The BP FETs was electrically measured every 20 minutes (1cycle) in the air, the total cycle is 100. We show electrical changes with Mobility, On/off ratio, Current and a significant positive shift in the threshold voltage. We extracted the current level at Vgs-Vth = 0, -10, -20 and fitting with Swiss-cheese model. This model suggested that Swiss-cheese model is well fitted with degradation pattern of BP FETs.

• Journal of the Korean Vacuum Society
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• v.10 no.2
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• pp.207-212
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• 2001

In this study, synthesis condition of $TiO_2$ thin films which have optimal dielectric characteristics using sol-gel method was determined. Thin films were fabricated using sol which have optimal characteristics and their permittivity was measured. In case of the amount of water for hydrolysis smaller than that for stoichiometry, sol formed clear sol which have normal chain structure. On the contrary, in case of the amount of water for hydrolysis larger than that for stoichiometry, sol formed suspended sol which have cluster structure. The permittivity of thin films increased exponentially around $^{\circ}C$.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.3
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• pp.588-593
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• 2007

The 600kJ class high temperature superconducting magnetic energy storage (HTS SMES) system is being developed by Korean Electrotechnology Research Institute (KERI). The system is operated in cryogenic temperature and high vacuum condition. The SMS magnet was cooled by conduction cooling method using a Gifford-McMahon cycle cryocooler. Thus, electric insulation design at cryogenic temperature and high vacuum is a key and an important element that should be established to accomplish compact design is a big advantage of HTS SMES. This paper describes the electric insulation design, fabrication and experimental results for a mini model of conduction cooled HTS SMES.

• Journal of Korea Multimedia Society
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• v.18 no.11
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• pp.1400-1407
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• 2015

In the paper, we suggest bettered EHMECS(Enhanced Hybrid Multi Electrical Cupping System) to regulate automatically vacuum pressure using many cupping cup at once. We controlled accurately the pressure using S-PI control technique in pump motor to input the air inside cupping cup. S-PI control compared constant velocity, load and velocity variance between existing PI and FLC(Fuzzy Logic Control). The stabilization time of suggested S-PI control improve 20% of existing PI and 8% of FLC. The error constant of normal condition improved 71% of existing PI and 62% of FLC in steady speed and 80% of existing PI and 67% of FLC in load change. Also the error constant about velocity variance improve 45% of PI control. It is prove the suggested S-PI control technique. When use long time vacuum pressure of cupping cup regulated the suggested S-PI control technique, can loosen knotted muscles.

• Journal of Powder Materials
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• v.6 no.3
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• pp.231-237
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• 1999

In this study, the characteristics of gas atomized Mg-3wt%Al-1wt%Zn-1wt%MM alloy powders under vacuum condition were investigated. In spite of the low fluidity and easy oxidation of the molten magnesium, the spherical powders could be successfully produced by using a modified three pieces nozzle attached to the gas atomization unit. It was found that most of the solidified powders less than 50$\mu$m in diameter were single crystal and the solidified structure showed a typical dendritic morphology due to supercooling prior to nucleation. The secondary dendrite arm spacing decreased as the size of powders decreased. The Mg-Al-Ce intermetallic compounds with chemically stable phase were found in the interdendritic regions of $\alpha$-Mg. It is considered that formation of the chemically stable phase may possibly affect to improve the corrosion resistance. Therefore, it is expected that the materials formed of these Mg-Al-Zn-MM alloy powders shows better mechanical properties and corrosion resistance due to the structural refinement.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2002.05a
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• pp.36-36
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• 2002

Effects of pulse-plating on the wear and corrosion resistance of chrome-carbon layers were studied. The plating were carried out at $06A/\textrm{cm}^2$ in modified Sargent bath containing formic acid at $53^{\circ}C$. The chrome layer were super-saturated with carbon up to 2.0wt. %, which precipitated as chrome carbide such as $Cr_{23}C_6$ after vacuum aging above $200^{\circ}C$ for 1 hour. This resulted in improvement of hardness and wear resistance of the chrome layer. Considering the reduction of corrosion resistance due to the thermal effect, optimum vacuum aging condition of the chrome layer in this study was I-hour at $200^{\circ}C$.

• Journal of Korean Vacuum Science & Technology
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• v.6 no.1
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• pp.51-54
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• 2002

Polymer EL devices of glass/ITO/PI/MEH-PPV/Al structure were fabricated using spin coating and the Ionized Cluster Beam deposition technique. PMDA-ODA type thin polyimide films which can be used as a impurity blocking layer of EL device were deposited by ICB. According to our previous results, the packing densities of polyimide films were subject to change and depend on their deposition condition. By inserting a Pl layer with various thickness and packing density, I-V characteristics and life time of the devices were investigated to determine the role of a interlayer. The blocking of impurity diffusion from ITO to luminescent layer were confirmed by XPS.

• Journal of the Korean Vacuum Society
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• v.15 no.5
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• pp.475-484
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• 2006

The deformation, the stress distribution, and the contact pressure of gaskets used in sealing flanges of CF (Con-Flat) or IPD (Improved) type were calculated to investigate the possibility of analyzing and estimatimg the sealing performance under a given tightening condition for a specific flange system.