• Journal of the Microelectronics and Packaging Society
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• v.8 no.3
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• pp.49-53
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• 2001

Vortical etching experiments of ($SrBi_2Ta_2O_9$)/Si thin films have been performed by using the inductively coupled plasma reactive ion etching (ICP-ME) apparatus. The purposes of these experiments are to get the effective area of vertical surface. Because this technology is very important to get good qualities of ferroelectric gate structure, capacitor and the minimum parasitic effects related to the excellent performances of the FRAM (Ferroelectric Random Access Memory) device. The reacting gases were Ar and $Cl_2$gases, and various $Ar/C1_2$flow ratios were used. The etching experiments were carried out at various RF powers such as 700, 700, 500W and at various DC powers such as 200, 150, 100, 50W, respectively. The maximum etch rate of $SrBi_2Ta_2O_9$/Si thin films was 1050 A/min at the $Ar/C1_2$ gas ratio of 20/16, RF power of 700 W and DC power of 200 W. From the SEM (scanning electron microscopy) image of the SBT thin films, the wall angle was as good as about $82^{\circ}$.

• Korean Journal of Clinical Pharmacy
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• v.8 no.2
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• pp.107-112
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• 1998

Lovastatin is a lipid lowering agent for the treatment of hypercholesterolemia and belongs to a new class of pharmacologic compounds called the 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors. By competitively inhibiting HMG CoA reductase, lovastatin disrupts the biosynthesis of cholesterol in hepatic and peripheral cells and increases the synthesis of high-density-lipoprotein HDL) receptors. Following oral administration, the lactone ring of lovastatin is hydrolysed to the active inhibitor of HMG CoA reductase, lovastatin acid. Lovastatin is known to have poor oral absorption and wide individual variation. In this study, bioequivalence test of two lovastatin formulations, the test drug ($Lovaload^{TM}$, Chong Kun Dang Pharmaceutical Co.) and the reference drug ($Mevacor^{TM}$, Chung Wae Pharmaceutical Co.) were conducted according to the guidelines of Korea Food and Drug Administration (KFDA). A total of 18 healthy male volunteers, $31.90\pm3.60$ years old and $72.17\;7.88$ kg of body weight in average, were evaluated in a randomized crossover manner with a 2-week washout period. Concentrations of lovastatin acid in plasma were measured upto 12 hours following a single oral administration of eight tablets (20 mg of lovastatin per tablet) by high-performance liquid chromatography with UV detection at 238 nm. The area under the concentration-vs-time curve from 0 to 12 hours $(AUC_{0-12h})$ was calculated by the trapezoidal summation method. The statistical analysis showed that there are no significant differences in $AUC_{0-12h),\;C_{max}\;and\;T_{max}$ between the two formulations ($6.72\%,\;1.52\%,\;and\;0.88\$, respectively). The least significant differences between the formulations at $\alpha$=0.05 were less than $20\%\;(11.65\%,\;19.73\%,\;and\;14.81\%\;for\;AUC_{0-12h},\;C_{max}\;and\;T_{max}$, respectively). The $90\%$ confidence intervals for these parameters were also within $\pm20\%\;(-1.50{\leq}{\delta}{\leq}15.00$, $-12.50{\leq}{\delta}{\leq}15.50,\;and\;-9.64{\leq}{\delta]{\leq}11.40{\leq}\;for\;\;AUC_{0-12h}$ ,$C_{max}\;and\;T_{max}$, respectively). In conclusion, the new generic product $Lovaload^{TM}$ was proven to be bioequivalent with the reference drug.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.1
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• pp.84-95
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• 2001

Titanium is widely used in dentistry for its low density, high strength, fatigue resistance, corrosion resistance, and biocompatibility. But it has a tendency of surface damage under circumstance of friction and impact for its low hardness of the surface. Coating is one of methods fir increasing surface hardness. Its effect is to improve surface physical characteristics without change of titanium. Diamond-like carbon and titanium nitride are known for its high hardness of the surface. So that this study was aimed at the wear test and the cytotoxicity test of the commercially pure titanium and Ti-6Al-4V alloy which were deposited by diamond-like carbon film or titanium nitride film to acertain improvement of the surface hardness and the biocompatibility. A disk (25mm diameter, 2mm thickness) was made of commercially pure titanium and Ti-6Al-4V alloy and these substrates were deposited by diamond-like carbon film or titanium nitride film. Diamond-like carbon film was deposited by the method of radiofrequency plasma assisted chemical vapor deposition and titanium nitride film was deposited by the method of reactive arc ion plating. Then these substrates were tested about wear characteristics by the pin-on-disk type wear tester in which ruby ball was used as a wear causer under the load of 32N, The fracture cycles were measured by rotating the substrates until their films were fractured. The wear volume was measured after 150 cycles and 3,000 cycles using surface profiler. The cytotoxicity test was peformed by the method of the MTT assay. The results were as follows : 1. In the results of the wear volume test, commercially pure titanium and titanium alloy which were coated by diamond-like carbon film or titanium nitride aim had higher resistance against wear than the substrates which were not coated by any films (P<0.05). 2. In the results of the fracture cycle test and the wear volume test, diamond-like carbon film had higher resistance against wear than titanium nitride film (P<0.05). 3. In both coatings of diamond-like carbon aim and titanium nitride film, Ti-6Al-4V alloy had higher resistance against wear than commercially pure titanium (P<0.05) 4. In the results of the cytotoxicity test, diamond-like carbon film and titanium nitride film had little cytotoxicity as like commercially pure titanium or Ti-6Al-4V alloy (P>0.05).

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.435-441
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• 2012

The direct conversion of cellulose into polyols in $H_2$ was examined over Pt catalysts supported on various zeolites, viz., mordenite, Y, ferrierite, and ${\beta}$. For comparison, Pt catalysts supported on ${\gamma}-Al_2O_3$, $SiO_2-Al_2O_3$, and $SiO_2$ were also tested. The physical properties of the catalysts were probed with $N_2$ physisorption. The surface acidity was measured with temperature programmed desorption of ammonia ($NH_3$-TPD). The Pt content was quantified with inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The Pt dispersion was determined with CO chemisorptions and transmission electron microscopy (TEM). The conversion of cellulose appeared to be mainly dependent on the reaction temperature and reaction time because it depends on the concentration of $H^+$ ions reversibly formed in hot water. Pt/H-mordenite (20) showed the highest yield to polyols among the tested catalysts. Pt/H-zeolite was superior to Pt/Na-zeolite for this reaction. The polyol yield was dependent on the surface acid density and the external surface area.

• Journal of the Korean Magnetics Society
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• v.17 no.4
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• pp.166-171
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• 2007

We report the magneto-transport properties of an individual single crystalline Bi nanowire grown by a spontaneous growth method. We have successfully fabricated a four-terminal device based on an individual 400-nm-diameter nanowire using plasma etching technique to remove an oxide layer forming on the outer surface of the nanowire. The transverse MR (2496% at 110 K) and longitudinal MR ratios (38% at 2 K) for the Bi nanowire were found to be the largest known values in Bi nanowires. This result demonstrates that the Bi nanowires grown by the spontaneous growth method are the highest-quality single crystalline in the literatures ever reported. We find that temperature dependence of Fermi energy ($E_F$) and band overlap (${\triangle}_0$) leads to the imbalance between electron concentration ($n_e$) and hole concentration ($n_h$) in the Bi nanowire, which is good agreement with the calculated $n_e\;and\;n_h$ from the respective density of states, N(E), for electrons and holes. We also find that the imbalance of $n_e\;and\;n_h$ plays a crucial role in determining magnetoresistance (MR) at T<75 K for $R_T$ and at T<205 K for $R_L$, while mean-free path is responsible for MR at T>75 K for $R_T$ and T>205 K for $R_L$.

• Korean Journal of Materials Research
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• v.11 no.3
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• pp.197-202
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• 2001

M $g_{1-x}$ Z $n_{x}$O thin films with various composition x of ZnO were fabricated by a RF magnetron sputtering method, which is expected to improve the electro-optical properties of the conventional MgO protective layer for AC-PDP. Test panels with the $Mg_{1-x}$Z $n_{x}$O protective layer have been fabricated in order to investigate the effects of ZnO doping on the electrical characteristics of devices such as the discharge voltages and the memory gain. Experimental results revealed that test panels with the $Mg_{1-x}$Z $n_{x}$O(x=0.5at%) protective layer show lower firing and sustain voltages than those seen in panels with MgO protective layer by 20V. resulting in an increasement of the memory coefficient. In addition, it was found that test panels with the $Mg_{1-x}$Z $n_{x}$O protective layer show higher discharge intensity, i. e., higher plasma density, compared with panels with MgO protective layer.ve layer.layer.

• Korean Journal of Materials Research
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• v.10 no.4
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• pp.282-289
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• 2000

$PbTiO_3$ films were fabricated by electron cyclotron resonance plasma enhanced chemical vapor deposition(ECR-PECVD). Deposition characteristics of $PbTiO_3$films on $RuO_2$ and Pt substrates were investigated with varying the flow rate of metalorganic source and substrate temperature. The residence time of Pb-oxide molecules in much longer on $RuO_2$ than on Pt substrate, while the perovskite nucleation is more difficult on $RuO_2$ than on Pt substrate. Therefore, the process conditions to obtain the single perovskite $PbTiO_3$ phase are more restricted on $RuO_2$ than on Pt substrates. An introduction of Ti-oxide seed layer increases perovskite nucleation density and thus enlarges the process window to obtain the single perovkite phase. The introduction of Ti-oxide seed layer make the PZT film that Ti-components of $PbTiO_3$ are partially substituted with Zr atoms have single perovskite phase for the wide range of Zr/(Zr+Ti) concentration ratios.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.37.2-37.2
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• 2011

Our previous study on tiny pores (R < 2") observed by HINODE/Solar Optical Telescope (SOT) revealed that the plasma in the pores at the photosphere is always moving down and the pores are surrounded by the strong downward motions (highly red-shifted) of neighboring granulations. From this study, we speculated that the flow motions above the pore should be related with the motions at the photosphere, since the pore is strong magnetic field region. Meanwhile, SNU and KASI installed Fast Imaging Solar Spectrograph (FISS) in the Cude room of the 1.6 m New Solar Telescope (NST) at Big Bear Solar Observatory. FISS is a unique system that can do imaging of H-alpha and Ca II 8542 band simultaneously, which is quite suitable for studying of dynamics of chromosphere. To get some clue on the relationship between the photospheric and low-chromospheric motions at the pore region, we took a coordinate observation with NST/FISS and Hinode/SOT for new emerging active region (AR11117) on October 26, 2010. In the observed region, we could find two tiny pores and two small magnetic islands (SMIs), which have similar magnetic flux with the pores but does not look dark. Magnetic flux density and Doppler velocities at the photosphere are estimated by applying the center-of-gravity (COG) method to the HINODE/spectropolarimeter (SP) data. The line-of-sight motions above the photosphere are determined by adopting the bisector method to the wing spectra of Ha and CaII 8542 lines. As results, we found the followings. (1) There are upflow motion on the pores and downflow motion on the SMIs. (2) Towards the CaII 8542 line center, upflow motion decrease and turn to downward motion in pores, while the speed of down flow motion increases in the SMIs. (3) There is oscillating motion above pores and the SMIs, and this motion keep its pattern along the height. (4) As height increase, there is a general tendency of the speed shift to downward on pores and the SMIs. This is more clearly seen on the other regions of stronger magnetic field. In this talk, we will present preliminary understanding of the coupling of pore dynamics between the photosphere and the low-chromosphere.

• Applied Biological Chemistry
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• v.43 no.3
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• pp.190-195
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• 2000

Tolaasin is a peptide toxin produced by Pseudomonas tolaasii and causes a brown blotch disease forming brown, slightly sunken spots and blotches on the cultivated mushrooms. It is a lipodepsipeptide consisting of 18 amino acids and its molecular mass is 1,985 Da. It forms a pore in plasma membranes, resulting in the disruption of membranes of fungal, bacterial, plant, and animal cells as well as mushroom tissue. In order to measure the toxicity of tolaasin, erythrocytes of blood were used to evaluate the tolaasin-induced hemolysis. Hemolytic activity of tolaasin was measured by observing the absorbance change either at 420 nm, representing the release of hemoglobins from red blood cells(RBCs), or at 600 nm, representing the density of residual cells. The hemolytic activity of culture-extract of P. tolaasii increased at early-stationary phase of growth and was maximal at late stationary phase. The hemolytic activity of tolaasin appeared high in the RBCs of dog and rat. The RBCs of rabbit and hen were less susceptible to tolaasin. The effects of various cations were also measured. $Cd^{2+}$ and $La^{3+}$. as well as $Zn^{2+}$ appeared inhibitory to the tolaasin-induced hemolysis. The effects of various anions on tolaasin-induced hemolysis were measured and carbonate showed the greatest inhibition to the hemolysis. However, phosphate stimulated the tolaasin-induced hemolysis and no effects were observed by chloride and nitrate.

• Korean Journal of Materials Research
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• v.7 no.3
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• pp.196-202
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• 1997

Perovskite lanthanum doped lead titanate ($(Pb,La)TiO_{3}$ or PLT) thin films were successfully fabricated on Pt/TijSiO.iSi substrates at the temperatures as low as $440~500^{\circ}C$ by eleclron cyclotron resonance plasma-enhanced chemical vapor deposition (ECR PECVII). Since the volatilities of the MC sources arid oxide molecules (especially Ph oxide) increased with increasing deposition temperature, the film deposition rate and the (I'b + La)/'Ti ratio decreased Stoichiometric perovskite PL'T films with good dielectric and leakeage current properties were obtained at the temperatures of $460~480^{\circ}C$. The lanthanum content of the film was nearly directly propotional to $La(DPM)_{3}$ flow rate. As the La/Ti ratio increased from 3.0 to 9.5%, the dielectric constant increased from 360 to 650 and the leakeage current density at 100kV/cm electric field decreased from $4{\times}10^{-5}$ to $4{\times}10_{-8}A/cm^2$.