• Journal of ILASS-Korea
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• v.10 no.4
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• pp.1-7
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• 2005

The purpose of this study is to investigate the effect of swirler vane angle and the aspect ratio of swirl chamber of nozzle on the characteristics of single spray. The characteristics of sprat's have been investigated by measuring the spray angle, droplet size and velocity Visualization of spray was conducted to obtain the spray angle and breakup process. The spray characteristics such as droplet size and velocity were measured by Phase Doppler Anemometry(PDA). It was found that the spray angle was increased with increasing the swirler angle. For both sprays, the axial velocity and SMD were decreased with increasing the swirler vane angle. It was also shown that the axial velocity and SMD were decreased with increasing the aspect ratio of swirl chamber The effect of vane angle un the spray characteristics was greater than the aspect ratio of swirl chamber for single spray.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.183-183
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• 1999

The phases and interface formation of MgF2 on Si(111) were studied by using LEED, AES, and TPD. When thick MgF2 film was deposited on the Si(111) surface at RT뭉 annealed at higher temperatures, a sequence of LEED patterns (no LEED pattern $\longrightarrow$1$\times$1$\longrightarrow$3$\times$1$\longrightarrow$7$\times$7) was observed. On the 1$\times$1 model in which Mg adsorbs on T4 site and F on H3 site could explain the simultaneous desorption of SiF2 and Mg. When thin MgF2 film was deposited, and initial $\alpha$-$\times$1 phase transforms to 3$\times$3 and $\beta$-1$\times$1 by thermal annealing with a slow evaporation of F and diffusion of Mg into the surface. the 3$\times$3 surface changes to ${\gamma}$-1$\times$1 by the selective desorptioon of F under e-beam irradiation and subsesquently to a Mg-induced {{{{ SQRT { 3} }}}} structure by annealing at $600^{\circ}C$.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2462-2464
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• 2005

The AC-DC converter, which has three-phase AC power as input and isolated DC power as output is used for the regulated DC power supply of the telecommunication power processing system for several kilowatt class applications. The conventional DC power supply for the telecommunication power system comprises a PWM rectifier with sine-wave shaping input current unity power factor and a DC/DC converter connected to the PWM converter, which obtains DC 48[V]. Since power passes through these two power stage converters, the conversion power loss is difficult to provide high efficiency. To resolve these problems, this paper presents a new PWM rectified as a 1-stage power conversion method. It simulation and experimental results as proved from a Practical point of view that 92.1[%]of conversion efficiency and input current which can meet harmonics regulation of the Class-A in IEC61000-3-3 are achieved.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1820-1822
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• 2005

The AC-DC converter, which has three-phase AC power as input and isolated DC power as output is used for the regulated DC power supply of the telecommunication power processing system for several kilowatt class applications. The conventional DC power supply for the telecommunication power system comprises a PWM rectifier with sine-wave shaping input current unity power factor and a DC/DC converter connected to the PWM converter, which obtains DC 48[V]. Since power passes through these two power stage converters, the conversion power loss is difficult to provide high efficiency. To resolve these problems, this paper presents a new PWM rectified as a 1-stage power conversion method. It simulation and experimental results as proved from a practical point of view that 92.1[%]of conversion efficiency and input current which can meet harmonics regulation of the Class-A in IEC61000-3-3 are achieved.

• Bulletin of the Korean Chemical Society
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• v.14 no.5
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• pp.583-588
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• 1993

Encapsulation capacities $(V_{gas})$ of, $H_2,\;N_2,\;CO,\;CH_4$ and CO, for $Cs_{2.5}Na_{9.5}-A (C_s-A)$ and $Na_{12}$-A (Na-A) zeolites have been measured in order to understand the effect of molecular properties on the $V_{gas}$. With appropriate number of large blocking cations on the main windows of cavities in zeolite A, gas molecules can be encapsulated in both the ${\alpha}$ -and ${\beta}$-cages, resulting in much large $V_{gas}.\;V_{gas}$ is proportional to the encapsulation pressure (Pe) and is also dependent on the molecular properties of encapsulated gases themselves, especially on intermolecular forces originated from the quadrupole moments of molecules in the molecular-dimensioned cavities of zeolite A. At the low range of Pe, molecules with larger $V_{gas}$ and intermolecular forces apparently have smaller increasing tendencies of $V_{gas}$ upon increases in Pe, showing a linear relationship between the tendencies and intermolecular forces rather than their sizes. Interactions between encapsulated molecules of $CH_4$ and framework of Cs-A have been estimated and they seem to depend on the number of encapsulated molecules per unit cell. On the basis of calculated density of $CO_2$, presence of liquid-like phase for the encapsulated molecules in the molecular dimensioned cavities of zeolite A is postulated.

• Korean Journal of Optics and Photonics
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• v.17 no.5
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• pp.391-395
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• 2006

In this paper, radiometric calibration of a FTIR spectrometer for passive remote sensing application was introduced and verified. Radiometric calibration is a significant signal processing procedure to retrieve the object radiance from the measured spectrum. The object radiance is measured and registered distorted by the detector's responsivity dependent on wavelength and instrument self-emission. Radiance of two temperature points, hot temperature and cold temperature, from a well-controlled blackbody was measured and used to obtain the scale factor and offset factor which are required for radiometric calibration. For gas phase C2H5OH. radiometric calibration was done and verified through comparison of its emission line width and intensity with the standard spectrum.

• Journal of the Korean Vacuum Society
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• v.6 no.S1
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• pp.75-79
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• 1997

Optical and mechanical characteristics of $TiO-2, ZrO_2 \;and\; SiO_xN_y$ thin films prepared by ion assisted deposition (IAD) were investigated. IAD films were bombarded by Ar or nitrogen ion beam from a Kaufman ion source while they were grown in as e-beam evaporator. The result shows that the Ae IAD increases the refractive index and packing density of $TiO_2 films close to those of the bulk. For $ZrO_2$ films the Ar IAD increases the average refractive index decreases the negative inhomogeneity of refractive index and reverses to the positive inhomogeneity. The optical properties result from improved packing density and denser outer layer next to air The Ar-ion bombardment also induces the changes in microstructure of $ZrO_2$ films such as the preferred (111) orientation of cubic phase increase in compressive stress and reduction of surface roughness. Inhomogeneous refractive index SiOxNy films were also prepared by nitrogen IAD and variable refractive index of $SiO_xN_y$ film was applied to fabricate a rugate filter.

• Analytical Science and Technology
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• v.36 no.1
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• pp.53-58
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• 2023

2'-Hydroxy-3',4'-methylenedioxy-3,4,5-trimethoxychalcone (HMTC) is a newly synthesized chalcone that affects proliferation, cytotoxic potential and apoptosis in human leukemia cells. However, no validated determination method has been described so far for HMTC in biological samples. Thus, we developed a liquid chromatographic method using a tandem mass spectrometry to determine HMTC in rat plasma. Liquid-liquid extraction with ethyl acetate was used for the clean-up procedure. The analyte was separated on a reversedphase column with mobile phase of distilled water and acetonitrile (2:8, v/v, including 0.1 % formic acid). The ion transition of the precursor to the product ion was principally deprotonated ions [M-H]^- at m/z 356.8 → 327.2 for HMTC. This analytical method was successfully applied in pharmacokinetic study of HMTC after intravenous administration in rats.

• The Korean Journal of Zoology
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• v.39 no.1
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• pp.36-46
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• 1996

An endogenous phenoloxidase (EPO) from earthworm, Lumbricus rubellus, has been purified and characterized. The purified EPO using ammonium sulfate fractionation, Blue-2, Phenyl-, and Q-sepharose chromatography steps was revealed in SDS-PAGE as a single protein banri with Mr. of 59 kl)a. A native strudure of the enzyme was examined with an in situ staining of a nondenatudng-PAGE using DL-dopa as a substrate. The result showed that a single band due to the EPO activity was located siighdy above a standard polypeptide with Mr. of 210 kl)a. These fads indicate that the EPO is an oligomeric enzyme. The presence of a monophenolase activity of the purified EPO, which hydroxylates tyrosine to dopa, was confirmed by observing dopachrome accumulation at 475 nm at PH 8.0 with a typical lag phase during 60 mm. of meausrement. A series of inhibition study has been performed for the enzyme with several divalent cation chelators such as phenyithiourea (Flu), 1, lO-phenanthroline, EDTA, and EGTA. Among them, only V'flj inhibited the enzyme with 1C0.5 of 65 MM, which indicated that copper was critical for the catalysis of EPO. The enzyme was maximally active at 35'C and pH 8.0 when L-dopa to dopachrome conversion was spectrophotometricaily monitored at 475 nm. The apparent Km values of P0 for L-opa were obtained as 1.86 mM and 13.8 mM at pH 6.5 and 8.0, respectively. The catalytic efficiencies at both pH were almost identical [(kat/Km)pH8.0/(kcat/Km)pH6.5 = O.92] while the Vmax at p11 8.0 was 6.6-fold higher than that at pH 6.5. This fact may indicate that pH affeds the catalysis at substrate and/or enzyme-substrate complex level rather than the enzyme itself. Taken together, the EPO was an oligomeric enzyme which did not require proteolysis for its activation. These results also indicated that the enzyme can exist, at least, in part as a latent form In vivo, which might be distinct from the prophenoloxidase activating system. Therefore, it is pertinent to consider that there must be certain regulatory molecules or phenomena in L. rubellus which make the 1,0 in a latent form in vivo before the foreign invasions.

• YAKHAK HOEJI
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• v.52 no.1
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• pp.7-11
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• 2008

A high performance liquid chromatographic (HPLC) method for the determination of glycyrrhizic acid was developed for the quality control of traditional herbal medicinal preparation Bu-Zhong-Yi-Qi-Tang (BZYQT), which is well-known herbal medicine used as tonic. RP-HPLC analysis was carried out using Capcell pak $C_{18}$ MG column $(5\;{\mu},\;150{\times}4.6\;mm)$ and a mobile phase consisting of acetonitrile and water containing 0.03% phosphoric acid (pH 2.46) at a flow rate of 1.0 ml/min. The optimum wavelength for the detection of the glycyrrhizic acid was found at 250 nm using diode-array UV/VIS detector. The glycyrrhizic acid in BZYQT shows good linearity $(r^2>0.999)$ in the range of $15\;{\mu}g/ml$ to 500 ${\mu}g/ml$. The limit of detection (LOD) was less than 5 ng and R.S.D for intra-day and inter-day reproducibility was less than 7%. The mean recovery of the glycyrrhizic acid was $97.3{\sim}113.0%$. These results suggest that the developed HPLC method is simple and efficient, and could be contributed for the quality control of commercial BZYQT products.