• Analytical Science and Technology
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• v.7 no.1
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• pp.103-114
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• 1994

The elution behaviors of Ni(II), Cu(II), Co(II), and Cr(II) in 1-phenyl-3-methyl-4(2-hydroxy-5-X-phenylazo)-5-pyrazolone, [Pm(2-OH)(5-X)PaPz](X=H, $CH_3$, $NO_2$, Cl) chelates have been studied by reversed phase HPLC. Thirteen metal-[Pm(2-OH)(5-X)PaPz] chelates were prepared and characterized by UV, IR, MS, and ICP spectroscopic methods. These metal-2-hydroxyarylazopyrazolone chelates were successfully separated on Novapak-$C_{18}$ column using methanol/water mixtures as a mobile phases. It was found that the chelates were eluted properly in an acceptable range of the capacity factor value($0{\leq}log\;k^{\prime}{\leq}1$). The dependence of the capacity factor(log k') on the volume fraction of water in the binary mobile phase showed a good linearity. Also, there was a good linear dependence of the capacity factor on the liquid-liquid extraction distribution ratio($D_c$) in methanol-water/n-pentadecane extraction system by the batch method. It suggested that the retention of the chelates in the reverse phase liquid chromatographic system be largely due to the solvophobic effect.

• Korean Journal of Food Science and Technology
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• v.24 no.3
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• pp.240-246
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• 1992

Preparation of soybean oil fatty acid methyl esters (soybean oil FAME) through the transesterification of soybean oil with alkaline catalyst was optimized in terms of contents of residual free fatty acids (FFA) in soybean oil FAME and yield of soybean oil FAME due to the inhibitory effect of FFA on sucrose polyesters synthesis. Soybean oil FAME and residual FFA were analyzed quantitatively by simultaneous gas chromatography on a fused silica capillary column after converting the FFA in soybean oil FAME to tert.-butyldimethylsilyl (TBDMS) derivatives. Transesterification of soybean oil was successfully performed with alkaline catalyst (NaOH, 95%), which resulted in 99.1% yield of soybean oil FAME and less than 0.1% residual FFA contents under the conditions such as $30^{\circ}C$, 20min. and 6:1 molar ratio of anhydrous methanol to soybean oil.

• Korean Journal of Medicinal Crop Science
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• v.14 no.2
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• pp.63-69
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• 2006

The methanolic (MeOH) extract of A. fruticosa bark, which showed immune-regulatory activities, was separated to purify an active compared by means of a multi-stage column chromatography. This resulted in the isolation and characterization of an isoflavone glycoside named 4', $6-Dimethoxyisoflavone-7-O-{\beta}-D-glucopyranoside$. Immuno-regulatory activities of the crude extract of Amorpha fruticosa LINNE bark were compared with that of an isoflavone glycoside (4', $6-dimethoxyisoflavone-7-O-{\beta}-D-glucopyranoside$). The crude methanolic extract of A. fruticosa and purified single compound showed 16% of relatively low cytotoxicity at a maximum concentration of 1.0 g/L in cultivated normal human lung cell line (HEL299). Cell growth of human T cells was increased up to 15%, 0.5 g/L of the crude extract added group. This was higher than a single compound added one. On the other hand, specific production rates of IL-6 and $TNF-{\alpha}$ from T cell were higher in the purified compound treat group ($0.82{\times}10^{-4}\;pg/cell$ and $1.08{\times}10^{-4}\;pg/cell$, respectively), compared to 0.5 g/L of the crude extract added group ($0.65{\times}10^{-4}\;pg/cell$ and $0.84{\times}10^{-4}\;pg/cell$, respectively). In addition, the growth of NK-92MI cells incubated with the crude extract was higher up to 56% over the cells grown with a single compound (0.5 g/L). In overall, the crude extract showed relatively higher immuno-regulatory activities compared with a single compound, probably due to the synergic effect given by other substances existed in the crude extract. Even though the siolated compound stimulated higher secretion of cytokines from human T cells.

• Korean Journal of Microbiology
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• v.43 no.1
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• pp.19-22
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• 2007

Acetohydroxyacid synthase (E.C.2.2.1.6., AHAS) is the enzyme that catalyses the first step in the synthesis of the branched-chain amino acids valine, leucine and isoleucine. The AHAS gene (TIGR access code HI2585) from Heamophilus influenzae was cloned into the bacterial expression vector pET-28a and expressed in the Escherichia coli strain BL21(DE3). The expressed enzyme was purified by $Ni^{2+}-charged$ HiTrap chelating HP column. The purified enzyme appears as a single band on SDS-PAGE with a molecular mass of about 63.9 kDa. The enzyme exhibits absolute dependence on the three cofactors FAD, $MgCl_{2}$ and thiamine diphosphate for activity. Specific activity of purified enzyme has 3.22 unit/mg and optimum activity in the pH 7.5 at $37^{\circ}C$. This enzyme activity has an effect on the buffer. When comparing the enzyme activity against the organic solvent, it followed in type and the difference it is but even from the aqueous solution where the organic solvent is included with the fact that the enzyme activity is maintained.

• Composites Research
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• v.18 no.6
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• pp.9-18
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• 2005

With the wide applications of fiber-reinforced composite material in aero-structures and mechanical parts, the design of composite joints have become a very important research area because the joints are often the weakest areas in composite structures. This paper presents an analytical study of the stress distributions in mechanically single-fastened and multi-fastened composite laminates. The finite element models which treat the pin and hole contact problem using a contact stress analysis are described. A dimensionless stress concentration factor is used to compare the stress distributions in composite laminates quantitatively In the case of single-pin loaded composite laminate, the effects of stacking sequence, the ratio of a hole diameter and the width of a laminate (W/D ratio), the ratio of hole diameter and distance from edge to hole (E/D ratio), friction coefficient and clamping force are considered. In the case of multi-pin loaded composite laminate, the influence of the number of pins, pitch distance, number of rows, row spacing and hole pattern are considered. The results show that P/D ratio and E/D ratio affect more on stress distributions near the hole boundary than the other factors. In the case of multi-pin loaded composite laminate, the stress concentration in the double column case is better than the other cases of multi-pin loaded composite laminate.

• Journal of the Korean Wood Science and Technology
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• v.12 no.3
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• pp.25-34
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• 1984

This experiment was carried out to investigate the effects of monosaccharides extracted by saturated portland cement solution on the cement setting in comparision with the inhibitory index (I) of each lignocellulosic-cement system. The wood species which have been widely reforested in Korea, Populus alba-grandulosa, Larix leptolepis, Abies holophylla, Pinus koraiensis, Pinus rigida, Pinus densiflora and agricultural wastes of rice husk and rice stalk were used at this study. The wood meal, 0.50g on dry weight basis, through 0.83 mm(20 mesh) and retained on 0.35mm (40 mesh) screen was extracted by 25 ml saturated portland cement solution and the pH of saturated portland cement solution Was 12.7. To eliminate cation exsisting in the extracted solution, the cation exchange column was used (Fig. 4). Afterwards the extracted monosaccharides were reduced into alditols with sodium borohydride and analyzed by the gas-liquid chromatography for xylan, mannan, arabinan, galactan, gluean. The heat of cement hydration for lignocellulosic-cement system was measured in Dewar flask (Fig. 2). And then the inhibitory indices were calculated from maximum hydration temperature, time and maximum slops of hydration curve of ligno cellulosic-cement systems. The results obtained were as follows; (1) The inhibitory index of pines-Pinus rigida (I=29.33) and Pinus densiflora (I=35.76), were lower than that of poplar-Populus alba-glandulosa (I=41.48), and the index of Larix ieptoiepis (I=73.00) was the highest among eight lignocellulosic-cement systems, and accordingly both Pinus rigida and Pinus des(flora were seemed to be good wood species for wood-cement composite manufacture. (2) In case of Pinus rigida, the inhibitory index was 29.33 and the ratio of the hexoses to the pemoses was 6.04 and in case of Larix leptolepis, the index and the ratio were 73.00 and 35.19, respectively. Therefore the inhibitory index increased with increasing the ratios of the hexoses to the pentoses. (3) The richer amount of xylose and mannose in species caused decreasing the slops of the hydration curve of the lignocellulosic-cement system, prohahly due to the chemical adsorption of the acetyl groups in the hemicellulose on the surface of cement grains. (4) The amoun of xylose and mannose were significant to the inhibitory index of each lignocellulosic-cement system but any specific relation between the amount of glucose and inhibitory index was not found.

• Journal of Broadcast Engineering
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• v.18 no.1
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• pp.21-30
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• 2013

It is a challenging problem to most of the image processing when the light source is unknown. The color of the light source must be estimated in order to compensate color changes. To estimate the color of the light source, additional assumption is need, so that we assumed color distribution according to the light source. If the pixels, which do not satisfy the assumption, are used, the estimation fails to provide an accurate result. The most popular color distribution assumption is Grey-World Assumption (GWA); it is the assumption that the color in each scene, the surface reflectance averages to gray or achromatic color over the entire images. In this paper, we analyze the characteristics of the camera response function, and the effect of the Grey-World Assumption on the pixel value and chromaticity, based on the inherent characteristics of the light source. Besides, we propose a novel method that detects important pixels for the color estimation of the light source. In our method, we firstly proposed a method that gives weights to pixels satisfying the assumption. Then, we proposed a pixel detection method, which we modified max-RGB method, to apply on the weighted pixels. Maximum weighted pixels in the column direction and row direction in one channel are detected. The performance of our method is verified through demonstrations in several real scenes. Proposed method better accurately estimate the color of the light than previous methods.

• Journal of Biosystems Engineering
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• v.41 no.2
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• pp.108-115
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• 2016

Purpose: Radio frequency (RF) heating is a promising thawing method, but it frequently causes undesirable problems such as non-uniform heating. This can occur because of the food shape, component distribution, and initial temperature differences between food parts. In this study, RF heating was applied to the thawing of cylindrically shaped pork sirloin by changing the shape of electrodes and the surrounding temperature. Methods: Curved electrodes were utilized to increase the thawing uniformity of cylindrically shaped frozen meat. Pork sirloin in the shape of a half-circle column was frozen in a deep freezer at $-70^{\circ}C$ and then thawed by RF heating with flat and curved electrodes. In order to prevent fast defrosting of the food surface by heat transfer from air to the food, the temperature of the thawing chamber was varied by -5, -10, and $-20^{\circ}C$. The temperature values of the frozen pork sirloin during RF thawing were measured using fiber-optic thermo sensors. Results: After multiple applications of curved electrodes resembling the food shape, and a cooled chamber at $-20^{\circ}C$ the half-cylindrically shaped meat was thawed without surface burning, and the temperature values of each point were similarly increased. However, with the parallel electrode, the frozen meat was partially burned by RF heating and the temperature values of center were overheated. The uniform heating rate and heat transfer prevention from air to the food were crucial factors for RF thawing. In this study, these crucial factors were accomplished by using a curved electrode and lowering the chamber temperature. Conclusions: The curved shape of the electrode and the equipotential surface calculated from the modeling of the parallel capacitor showed the effect of uniform heating of cylindrically shaped frozen food. Moreover, the low chamber temperature was effective on the prevention of the surface burning during RF thawing.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.2
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• pp.79-84
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• 2003

We have previously reported that expression of the somatostatin receptor subtypes, sst1-5, is differentially regulated by growth hormone (GH)-releasing hormone (GHRH) and forskolin (FSK), in vitro. GHRH binds to membrane receptors selectively located on pituitary somatotropes, activates adenylyl cyclase (AC) and increases sst1 and sst2 and decreases sst5 mRNA levels, without significantly altering the expression of sst3 and sst4. In contrast FSK directly activates AC in all pituitary cell types and increases sst1 and sst2 mRNA levels and decreases sst3, sst4 and sst5 expression. Two explanations could account for these differential effects: 1) GHRH inhibits sst3 and sst4 expression in somatotropes, but this inhibitory effect is masked by expression of these receptors in unresponsive pituitary cell types, and 2) FSK inhibits sst3 and sst4 expression levels in pituitary cell types other than somatotropes. To differentiate between these two possibilities, somatotropes were sequentially labeled with monkey anti-rat GH antiserum, biotinylated goat anti-human IgG, and streptavidin-PE and subsequently purified by fluorescent-activated cell sorting (FACS). The resultant cell population consisted of 95% somatotropes, as determined by GH immunohistochemistry using a primary GH antiserum different from that used for FACS sorting. Purified somatotropes were cultured for 3 days and treated for 4 h with vehicle, GHRH (10 nM) or FSK ($10{\mu}M$). Total RNA was isolated by column extraction and specific receptor mRNA levels were determined by semi-quantitative multiplex RT-PCR. Under basal conditions, the relative expression levels of the various somatostatin receptor subtypes were sst2＞sst5＞sst3=sst1＞ sst4. GHRH treatment increased sst1 and sst2 mRNA levels and decreased sst3, sst4 and sst5 mRNA levels in purified somatotropes, comparable to the effects of FSK on purified somatotropes and mixed pituitary cell cultures. Taken together, these results demonstrate that GHRH acutely modulates the expression of all somatostatin receptor subtypes within GH-producing cells and its actions are likely mediated by activation of AC.

• Korean Chemical Engineering Research
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• v.53 no.6
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• pp.723-729
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• 2015

The moment analysis of cyclic adenosine monophosphate (cAMP) was performed using chromatograms that were obtained with the pulse input method from an octadecyl silica (ODS) high-performance liquid chromatography (HPLC) column. The general rate (GR) model was employed to calculate the first absolute moment and the second central moment. Three important coefficients for moment analysis, which are molecular diffusivity ($D_m$), external mass transfer coefficient ($k_f$), and intra-particle diffusivity ($D_e$), were estimated by the Wilke-Chang equation, Wilson-Geankoplis equation, and comparing van Deemter equation to theoretical plate number equation, respectively. Experiments were conducted by various conditions of flow rates, methanol volume ratio of the mobile phase, and solute concentration. After the moment analysis, results were organized by van Deemter plots. Also van Deemter coefficients were compared each other to effect $H_{ax}$, $H_f$, and $H_d$ on height equivalent to a theoretical plate (HETP, $H_{total}$). The value of intraparticle diffusion ($H_d$) was the primary factor which makes for HETP whereas external mass transfer ($H_f$) was disregardable factor.