• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.4
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• pp.738-742
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• 2007

The variations in the device characteristics of hydrogenated amorphous thin-film transistors (a-Si:H TFTs) were studied according to the processes of pixel electrode fabrication to make active-matrix flat-panel displays. The off-state current was about 1 pA and the switching ratio was over $10^6$ before fabrication of pixel electrodes; however, the off-state current increased over 10 pA after fabrication of pixel electrodes. Surface treatment on SiNx passivation layers using plasma could improve the off-state characteristics after pixel electrode process. $N_2$ plasma treatment gave the best result. Charge accumulation on the SiNx passivation layer during the deposition of transparent conducting layer might cause the increase of off-state current after the fabrication of pixel electrodes.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1878-1880
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• 2005

In this research, We investigated the effect of $O_2/O_3$ Plasma treatment of indium-tin oxide (ITO) surface on the performance of organic light emitting devices (OLEDs). The OLED had a structure of ITO/N,N'-diphenyl-N,N' -(3-methylphenyl)-1, 1'-biphenyl-4-4'-diamine (TPD)/Tris (8-hydroxyquinolinato) Aluminum $(Alq_3)/Al$. The ITO surface was treated by $O_2/O_3$ plasma with different RF power chamber pressure and exposure time. As a result, the emission efficiency of the OLEDs could be improved obviously.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.190.1-190.1
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• 2016

One of the most serious problems faced by billions of people today is the availability of fresh water. According to statistics, 15% of the world's total output of dye products is discharged into the environment as dye wastewater, which seriously pollutes groundwater resources. For the treatment of chemically and biologically contaminated water the advanced oxidation processes (AOPs) shows the promising action. The main advantage with AOPs is the ability to degrade the organic pollutants to $CO_2$ and $H_2O$. For this degradation process the AOPs generation of powerful and non-selective radicals that may oxidize majority of the organic pollutants present in the water body. To generate the various reactive chemical species such as radicals (${\bullet}OH$, ${\bullet}H$, ${\bullet}O$, ${\bullet}HO_2$) and molecular species ($H_2O_2$, $H_2$, $O_2$) in large amount in water, we have used the atmospheric pressure plasma. Among the reactive and non-reactive species, the hydroxyl radical (${\bullet}OH$) plays important role due to its higher oxidation potential (E0: 2.8 V). Therefore, in this work we have checked the degradation of various dyes such as methyl orange, methylene blue and congo red using different type of atmospheric pressure plasma sources (Indirect jet and direct jet). To check the degradation we have used the UV-visible spectroscopy, HPLC and LC-MS spectroscopy. Further, to estimate role of ${\bullet}OH$ on the degradation of dyes we have studied the molecular dynamic simulation.

• Journal of the Korean institute of surface engineering
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• v.53 no.3
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• pp.87-94
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• 2020

Herein, sulfonated carbon nanotubes (CNT) have been prepared in dilute sulfuric acid (H₂SO₄) via a novel sulfonation approach based on gas-liquid interfacial plasma (GLIP) at room temperature. The sulfonic acid groups and total acid groups densities of CNT after GLIP treatment in 2 M H₂SO₄ for 45 min can reach to 0.53 mmol/g and 3.64 mmol/g, which is higher than that of sulfonated CNT prepared under 0.5 M / 1 M H₂SO₄. The plasma sulfonated CNT has been applied as catalysts for the conversion of microcrystalline cellulose to glucose. The effect of hydrolysis temperature and hydrolysis time on the conversion rate and product distribution have been discussed. It demonstrates that the total conversion rate of cellulose increasing with hydrolysis temperature and hydrolysis time. Furthermore, the GLIP sulfonated CNT prepared in 2 M H₂SO₄ for 45 min has shown high catalytic stability of 85.73 % after three cycle use.

• Carbon letters
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• v.6 no.2
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• pp.106-110
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• 2005

In this work, the effects of atmospheric oxygen plasma treatment of carbon fibers on mechanical interfacial properties of carbon fibers-reinforced epoxy matrix composites was studied. The surface properties of the carbon fibers were determined by acid/base values, Fourier-transform infrared spectrometer (FT-IR), and X-ray photoelectron spectroscopy (XPS) analyses. Also, the crack resistance properties of the composites were investigated in critical stress intensity factor ($K_{IC}$), and critical strain energy release rate mode II ($G_{IIC}$) measurements. As experimental results, FT-IR of the carbon fibers showed that the carboxyl/ester groups (C=O) at 1632 $cm^{-1}$ and hydroxyl group (O-H) at 3450 $cm^{-1}$ were observed for the plasma treated carbon fibers, and the treated carbon fibers had the higher O-H peak intensity than that of the untreated ones. The XPS results also indicated that the $O_{1S}/C_{1S}$ ratio of the carbon fiber surfaces treated by the oxygen plasma led to development of oxygen-containing functional groups. The mechanical interfacial properties of the composites, including $K_{IC}$ (critical stress intensity factor) and $G_{IIC}$ (critical strain energy release rate mode II), were also improved for the oxygen plasma-treated carbon fibersreinforced composites. These results could be explained that the oxygen plasma treatment played an important role to increase interfacial adhesions between carbon fibers and epoxy matrix resins in our composite system.

• Journal of Photoscience
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• v.4 no.2
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• pp.41-48
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• 1997

The plasma membrane and microsomes, isolated from the cells treated with hematoporphyrm derivative (HpD) for 1 and 24 h, accumulated the aggregated porphyrin. The quantity of aggregated porphyrin was same in the plasma membrane and microsomes after isolating them from cells treated with HpD for 1 h whereas the microsomes accumulated higher quantity of aggregated porphyrin when cells were treated with HpD for 24 h. Photodynamic action of aggregated porphyrin on plasma membrane and microsomes was investigated using lipid specific fluorescent probes: 1,6-diphenyl-1,3,5-hexatrine (DPH) and 1-(4-trimethylammonium), 6-diphenyl-1,3,5-hexatrine(TMA-DPH). The time dependent anisotropy of these probes in the membranes was measured and the decay of anisotropy was analyzed using wobbling in cone model. Upon irradiation both the plasma membrane and the microsomes showed an increase in the limiting anis~)tropy and order parameter and a decrease in the cone angle of the lipid probes. The increase in the limiting anisotropy was pronounced in membranes isolated from the cells treated with HpD for 24 h. Photoinduced change in the limiting anisotropy was dependent on the duration of incubation of cells with HpD before isolating the membranes. In both the membranes. the membrane core was affected more as compared to the outer leaflet. In addition to the structural changes, a decrease in Na$^+$-K$^+$-ATPase and NADPH cyt c reductase activity was also observed upon irradiation of HpD treated cells. Inhibition in NADPH cyt c reductase was more when cells were treated with HpD for 24 h, however, Na$^+$-K$^+$-ATPase activity did not depend on the duration of the treatment of cells with HpD before irradiation. Our results suggest that the extent of photoinduced perturbations in the membranes varies as a function of duration of the treatment of cells with HpD and the membrane core is more susceptible to the photodynamic action of aggregated porphyrin.

• Archives of Pharmacal Research
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• v.27 no.7
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• pp.806-810
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• 2004

Metformin is a biguanide antihyperglycemic agent often used for the treatment of non-insulin dependent diabetics (NIDDM). In this study, the pharmacokinetics and pharmacodynamics of metformin were investigated in Korean healthy volunteers during a fasting state for over 10 h. In order to evaluate the amount of glucose-lowering effect of metformin, the plasma concentrations of glucose were measured for a period of 10 h followed by the administration of metformin (oral 500 mg) or placebo. In addition, the concentration of metformin in blood samples was determined by HPLC assay for the drug. All volunteers were consumed with 12 g of white sugar 10 minutes after drug intake to maintain initial plasma glucose concentration. The time courses of the plasma concentration of metformin and the glucose-lowering effect were analyzed by nonlinear regression analysis. The estimated $C_{max}$, $T_{max}$, $CL_{t}$/F (apparent clearance), V/F(apparent volume of distribution), and half-life of metformin were 1.42$\{pm}$0.07 $\mu\textrm{g}$/mL, 2.59$\{pm}$0.18h, 66.12$\{pm}$4.6 L/h, 26.63 L, and 1.54 h respectively. Since a significant counterclock-wise hysteresis was found for the metformin concentration in the plasma-effect relationship, indirect response model was used to evaluate pharmacodynamic parameters for metformin. The mean concentration at half-maximum inhibition $IC_{50}$, $k_{in}$, $k_{out}$ were 2.26 $\mu\textrm{g}$/mL, 83.26 $H^{-1}$, and 0.68 $H^{-1}$, respectively. Therefore, the pharmacokinetic-pharmacodynamic model may be useful in the description for the relationship between plasma concentration of metformin and its glucose-lowering effect.

• Journal of the Korean institute of surface engineering
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• v.53 no.2
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• pp.43-52
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• 2020

Various aging treatments were conducted on AISI 630 martensitic precipitation hardening stainless steel in order to optimize aging condition. Aging treatment was carried out in the vacuum chamber of Ar gas with changing aging temperature from 380℃ to 430℃ and aging time from 2h to 8h at 400℃. After obtaining the optimized aging condition, several nitrocarburizing treatments were done without and with the aging treatment. Nitrocarburizing was performed on the samples with a gas mixture of H₂, N₂ and CH₄ for 15 h at vacuum pressure of 4.0 Torr and discharge voltage of 400V. The corrosion resistance was improved noticeably by combined process of aging and nitrocarburizing treatment, which is attributed to higher chromium and nitrogen content in the passive layer, as confirmed by XPS analysis. The optimized condition is finalized as, 4h aging at 400℃ and then subsequent nitrocarburizing at 400℃ with 25% nitrogen and 4% methane gas for 15h at vacuum pressure of 4.0 Torr and discharge voltage of 400V, resulting in the surface hardness of around 1300 HV_0.05 and α'_N layer thickness of around 11 ㎛ respectively.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.9
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• pp.1205-1209
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• 2000

The present study was undertaken to investigate the effect of stimulation of follicular development with eCG on the peripheral levels of inhibin and FSH in Murrah buffaloes. Estrus was synchronized in five normally cycling females by insertion of Crestar (Intervet, Boxmeer, Holland) implants for nine days. Estradiol valerate was administered i.m. on the day of implant insertion. On the 10th day of the induced estrous cycle a single dose of 3000 IU eCG (Folligon, Intervet, Boxmeer, Holland) was given, followed by treatment with 25 mg of $PGF_2$ alpha (Lutalyse, Upjohn, Belgium) 48 h later. Blood samples were obtained during the induced estrus, on cycle day 10 (luteal phase), at the superovulatory estrus (43 h after PGF) and during the periovulatory period (64 h after PGF). Ultrasonography was done daily to monitor follicular development. Plasma concentrations of inhibin and FSH were determined by specific radioimmunoassays. Differences between $mean{\pm}SEM$ values of different phases of the cycle were compared by ANOVA. The mean number of small (2-5 mm), medium (6-9 mm) and large (>10 mm) follicles observed two days after eCG treatment and on the day of superovulatory estrus was $2.8{\pm}0.31$, $5.2{\pm}0.30$ and $1.4{\pm}0.09$ and $1.9{\pm}0.21$, $2.8{\pm}0.40$ and $5.0{\pm}0.83$, respectively. The mean number of ovulations was $3.6{\pm}0.37$ and the mean number of unovulated follicles was $6.1{\pm}0.47$. Most of the follicles >10 mm in diameter had ovulated (72%). The mean ${\pm}SEM $ of plasma inhibin concentration $(2584.15{\pm}17.92pg/ml)$ during the superovulatory estrus was significantly higher $(p{\leq}0.05)$ than during the induced estrus $(749.87{\pm}17.29pg/ml)$, the luteal phase $(1099.54{\pm}24.98pg/ml)$ and periovulatory period $(1682.71{\pm}29.88pg/ml)$, respectively. $Mean{\pm}SEM$ plasma FSH concentration during the induced estrus $(10.35{\pm}0.41ng/ml)$ was not different from that during the superovulatory estrus $(8.52{\pm}0.39ng/ml)$, but was significantly higher $(p{\leq}0.05)$ than during the luteal phase $(2.81{\pm}0.42ng/ml)$ and periovulatory period $(5.7{\pm}0.28ng/ml)$. These data indicate that treatment with eCG in buffaloes for inducing superovulation results in a significant elevation in plasma inhibin levels and a decrease in plasma FSH levels during the superovulatory estrus. Thus, we suggest that the elevated plasma inhibin coming from fully developed follicles continued for a long time which results in inhibition of FSH leading to poor ovulation in the remaining follicles, which may be the cause of suboptimal superovulatory response.

• Journal of the Korean Society for Heat Treatment
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• v.3 no.1
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• pp.1-7
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• 1990

To investigate the influence of r.f. power and electrode distance on the TiN deposition, TiN films were deposited onto STC3, STD11 steel and Si-wafer from gas mixtures of $TiC_4/N_2/H_2$ using the radio frequency plasma assisted chemical vapor deposition. The crystallinity of TiN film could be improved by the increase of r.f. power and the decrease of electrode distance. The TiN coated layer contains chlorine, its content were decreased with increasing r.f. power as well as decreasing electrode distance. And the thickness of deposited TiN was largely affected by r.f. power and electrode distance. The hardness of deposited TiN reached a maximum value of about Hv 2,000.