• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05a
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• pp.53-56
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• 2004

The a-Si:H TFT using ferroelectric of SrTi $O_3$as a gate insulator is fabricated on glass. Dielectric characteristics of ferroelectric are superior to $SiO_2$and S $i_3$ $N_4$. Ferroelctric increases on-current, decreases thresh old voltage of TFT and also improves breakdown characteristics. The a-SiN:H has optical band gap of 2.61 eV, refractive index of 1.8~2.0 and resistivity of 10$^{13}$ - 10$^{15}$ $\Omega$cm, respectively. Insulating characteristics of ferroelectrics are excellent because dielectric constant of ferroelectric is about 60~100 and breakdown strength is over 1MV/cm. TFT using ferroelectric has channel length of 8~20${\mu}{\textrm}{m}$ and channel width of 80~200${\mu}{\textrm}{m}$. And it shows that drain current is 3.4$mutextrm{A}$ at 20 gate voltage, $I_{on}$ / $I_{off}$ is a ratio of 10$^{5}$ - 10$^{8}$ and $V_{th}$ is 4~5 volts, respectively. In the case of TFT without ferroelectric, it indicates that the drain current is 1.5 $mutextrm{A}$ at 20 gate voltage and $V_{th}$ is 5~6 volts. With the improvement of the ferroelectric thin film properties, the performance of TFT using this ferroelectric has advanced as a gate insulator fabrication technology is realized.zed.d.

• Nuclear Engineering and Technology
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• v.51 no.5
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• pp.1444-1450
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• 2019

The fast-neutron shielding behaviour (FNSB) of two clay-materials (Ball clay and Kaolin)of Southwestern Nigeria ($7.49^{\circ}N$, $4.55^{\circ}E$) have been investigated using effective removal cross section, ${\Sigma}_R(cm^{-1})$, mass removal cross section, ${\Sigma}_{R/{\rho}}(cm^2g^{-1})$ and Mean free path, ${\lambda}$ (cm). These parameters decide neutron shielding behaviour of any material. A computer program - WinNC-Toolkit has been used for computation of these parameters. The toolkit evaluates these parameters by using elemental compositions and densities of samples. The proficiency of WinNC-Toolkit code was probe by using MCNPX and GEANT4 to model fast neutron transmission of the samples under narrow beam geometry, intending to represent the actual experimental setup. Direct calculation of effective removal cross section ($cm^{-1}$) of the samples was also carried out. The results from each of the methods for each types of the studied clay-materials (Ball clay and Kaolin) shows similar trend. The trend might be the fingerprint of water content retained in each of the samples being baked at different temperature. The compositions of each sample have been obtained by Particle-Induced X-ray Emission (PIXE) technique (Tandem Pelletron Accelerator: 1.7 MV, Model 5SDH). The FNSB of the selected clay-materials have been compared with standard concrete. The cognizance of various factors such as availability, thermo-chemical stability and water retaining ability by the clay-samples can be analyzed for efficacy of the material for their FNSB.

• Natural Product Sciences
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• v.28 no.4
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• pp.187-193
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• 2022

Lysimachia christinae Hance was commonly used in Oriental medicine for treating the hepatitis virus, cholecystitis and cholagogic efficiency. According to the previous study, it possesses high antioxidant and anti-inflammatory activity. Simultaneous determination analytical method of isolated eight compounds, cynaroside (1), 2-(3,4-dimethoxyphenyl) ethyl O-α-L-arabinopyranosyl-(1→2)-O-[6-deoxy-α-L-mannopyranosyl-(1→3)] β-D-glucopyranoside (2), stearylester ricinoleic acid (3), (E)-4-(3,4-dimethoxyphenyl) but-3-en-1-yl palmitate (4), 2-hydroxy-24-methoxy-4-tetracosenoic acid (5), 2-hydroxy-24-propoxy-4-tetracosenoic acid (6), β-sitosterol (7), and androst-16-ene-3,6-diol (8) were established by using HPLC-DAD. This HPLC analysis was detected on a Dionex C18 column (5 ㎛, 120 Å, 4.6 mm × 150 mm) at 25℃. The mobile phase consisted of 0.1% trifluoroacetic acid and acetonitrile at a flow rate of 1 mL/min. Validation of the method was assessed by linearity, precision and accuracy test. Calibration curve was good at r² > 0.9998. Limits of detection (LOD) ranged from 0.19 to 8.18 g/ml and Limits of quantification (LOQ) ranged from 0.19 to 24.80 g/ml. The relative standard deviations (RSD) values of precision test, intra- and inter- day, were less than 0.99% and 1.0%. The accuracy test results ranged from 98.81% to 106.49% and RSD values were less than 0.95%. These results showed that the HPLC-DAD method was very reliable and accurate for the quantity analysis of eight compounds in L. christinae extract for quality control.

• Journal of Mechanical Science and Technology
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• v.20 no.1
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• pp.1-12
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• 2006

This work reviews the effects of catalyst formulation and exhaust gas composition on soot oxidation in CDPF (Catalytic Diesel Particulate Filter). DOC's (Diesel Oxidation Catalysts) have been loaded with Pt catalyst (Pt/$Al_{2}O_3$) for reduction of HC and CO. Recent CDPF's are coated with the Pt catalyst as well as additives like Mo, V, Ce, Co, Fe, La, Au, or Zr for the promotion of soot oxidation. Alkali (K, Na, Cs, Li) doping of metal catalyst tends to increase the activity of the catalysts in soot combustion. Effects of coexistence components are very important in the catalytic reaction of the soot. The soot oxidation rate of a few catalysts are improved by water vapor and NOx in the ambient. There are only a few reports available on the mechanism of the PM (particulate matter) oxidation on the catalysts. The mechanism of PM oxidation in the catalytic systems that meet new emission regulations of diesel engines has yet to be investigated. Future research will focus on catalysts that can not only oxidize PM at low temperature, but also reduce NOx, continuously self-cleaning diesel particulate filters, and selective catalysts for NOx reduction.

• Journal of Pharmaceutical Investigation
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• v.39 no.3
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• pp.167-171
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• 2009

Poly(lactic-co-glycolic acid) (PLGA) microspheres have been a useful tool as a controlled drug delivery system for peptides and proteins. Recently, porous microspheres have gained great attention as inhalation drug delivery system due to their low aerodynamic densities. Here, we report highly porous PLGA microspheres, which were prepared by using a single o/w emulsification/solvent evaporation method. Two types of porogen, i.e., (i) extractable Pluronic F127 and (ii) gas foaming salt of ammonium bicarbonate, were used to induce pores on the surface of PLGA microspheres. The respective preparation conditions on dp/cp ratio and porogen concentration were determined by the previous preliminary experiments, and other preparation factors were further optimized on the basis of PLGA Mw and porogen type. The morphological features examined by scanning electron microscope (SEM) show these porous microspheres have highly porous surface structure with a diameter range of 20${\sim}$30 ${\mu}$m. These highly porous PLGA microspheres, which have much lower density, would be a practical aerosol system for pulmonary drug delivery.

• Journal of computational fluids engineering
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• v.15 no.2
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• pp.86-94
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• 2010

A thermal-hydraulic code, named CUPID, has been developed for the analysis of transient two-phase flows in nuclear reactor components. A two-fluid three-field model was used for steam-water two-phase flows. To obtain numerical solutions, the finite volume method was applied over unstructured cell-centered meshes. In steam-water two-phase flows, a phase change, i.e., evaporation or condensation, results in a great change in the flow field because of substantial density difference between liquid and vapor phases. Thus, two-phase flows are very sensitive to the local pressure distribution that determines the phase change. This in turn puts emphasis on the accurate evaluation of local pressure gradient. This paper presents a new reconstruction method to evaluate the pressure gradient at cell centers on unstructured meshes. The results of the new scheme for a simple test function, a gravity-driven cavity, and a wall boiling two-phase flow are compared with those of the previous schemes in the CUPID code.

• Honam Mathematical Journal
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• v.16 no.1
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• pp.119-135
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• 1994

Let $Q_{n+p-1}(\alpha)$ denote the- dass of functions $$f(z)=z^{P}-\sum_{n=0}^\infty{a_{(p+k)}z^{p+k}$$ ($a_{p+k}{\geq}0$, $p{\in}N=\left{1,2,{\cdots}\right}$) which are analytic and p-valent in the unit disc $U=\left{z:{\mid}z:{\mid}<1\right}$ and satisfying $Re\left{\frac{D^{n+p-1}f(\approx))^{\prime}}{pz^{p-a}\right}>{\alpha},0{\leq}{\alpha}<1,n>-p,z{\in}U.$ In this paper we obtain sharp results concerning coefficient estimates, distortion theorem, closure theorems and radii of p-valent close-to- convexity, starlikeness and convexity for the class $Q_{n+p-1}$ ($\alpha$). We also obtain class preserving integral operators of the form $F(z)=\frac{c+p}{z^{c}}\int_{o}^{z}t^{c-1}f(t)dt.$ c>-p $F\left(z\right)=\frac{c+p}{z^{c}}\int_{0}^{z} t^{c-1}f\left(t \right)dt. \qquad c>-p$ for the class $Q_{n+p-1}$ ($\alpha$). Conversely when $F(z){\in}Q_{n+p-1}(\alpha)$, radius of p-valence of f(z) has been determined.

• Economic and Environmental Geology
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• v.9 no.3
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• pp.157-163
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• 1976

In this study, the oil bearing rock-sequence, U-hand-ri Formation (D.S. Lee et al., 1976), was subdivided into three members; the lower, the intermediate and the upper. The lower consists mainly of reddish purple tuff and sandy calcareous shales, the intermediate of an alternation of tuffs, sandstons, calcareous black shales, cherts and limestone and the upper of coarse grained variegated tuff and agglomerate. Oily matter was found from the black shales of the intermediate. Ten samples of black shales from drilled cores, 8 samples of black shales from different outcrops of the member, and 1 sample of grease-like seeping oil from black shales at U-hang-ri coast were chemically analyized. Among them, 9 samples contain remarkable amount of organic carbon (0.96~1.60%) and E.O.M. extract (0.176~0.718%), and mostly the bituminous material is saturated hydrocarbons as well as shown in infared spectroscopic analyses. The elemental analyses of MAE extracts and asphaltenes of some of thoese samples indicate that the transformation of organic material to crude oil is highly progressed. The authors suggest that the seeping oil and oily tinges in black shale layers are the products of natural cracking related with the igneous activities in the area nearby.

• Journal of Electrochemical Science and Technology
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• v.8 no.4
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• pp.294-306
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• 2017

Stainless steels and titanium alloys are widely used in the medical industry as replacement materials. These materials may be affected by the conditions and type of environment. In the same manner, soft drinks are widely consumed products. It is of interest for dental industry to know the behavior of medical-grade alloys when these are in contact with soft drinks, since any excessive ion release can suppose a risk for human health. In the present study, the electrochemical behavior of three stainless steel alloys and pure titanium was analyzed using three types of cola soft drinks as electrolyte. The objective of this study was to evaluate the response of these metallic materials in each type of solution (cola standard, light and zero). Different electrochemical techniques were used for the evaluation of the alloys, namely potentiodynamic polarization, linear polarization, and open-circuit potential measurements. The corrosion resistance of the stainless-steel alloys and titanium in the cola soft drinks was provided by the formation of a stable passive film formed by metal oxides. Scanning electron microscopy was used as a complementary technique to reveal corrosion phenomena at the surface of the materials evaluated.

• Bulletin of the Korean Chemical Society
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• v.27 no.10
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• pp.1597-1600
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• 2006

The mononuclear iron complex 1, $Fe^{III}$(Hbida)Cl($H_2O$), was synthesized using a tripodal tetradentate ligand, N-(benzimidazol-2-ylmethyl)iminodiacetic acid (H3bida), which has two carboxylate groups, one benzimida- zoyl group, and one tertiary amine where it serves as a tetradentate chelating ligand for the octahedral Fe(III) ion. The four equatorial positions of the octahedral complex are occupied by two monodentate carboxylates, a benzimidazole nitrogen, and an oxygen of a water molecule. One of the axial positions is occupied by an apical nitrogen of the Hbida and the other by a chloride anion. The mononuclear octahedral complex 1 mimics the geometry of the key intermediate structure of the catalytic reaction cycle proposed for the FeSODs, which is a distorted octahedral geometry with three histidyl imidazoles, an aspartyl carboxylate, a superoxide anion, and a water molecule. The redox potential of complex 1, $E_{1/2}$ is -0.11V vs. Ag/AgCl (0.12 V vs. NHE), which is slightly lower than those reported for the most FeSODs. The magnetic susceptibility of complex 1 at room temperature is 5.83 $\mu$B which is close to that of the spin only value, 5.92 $\mu$B of high-spin d5 Fe(III).