• Natural Product Sciences
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• v.17 no.4
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• pp.315-320
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• 2011

Routinely applicable HPLC assay procedures for the ganglioside content in various deer antler preparations were established through the creation of a UV-absorbing chromophoric substance - trans-${\alpha},{\beta}$-unsaturated-hexadecene-aldehyde - from the sphingosine moiety in ganglioside molecules by two step chemical reactions. In order to guarantee the assay's accuracy and sensitivity, the HPLC-assay procedure adopted internal reference procedures by mixing cis-${\alpha},{\beta}$-unsaturated-hexadecene aldehyde[V] or cis-3-heptadecene- 1,2-diol[IV] to assay samples. The internal reference compound [IV] or [V] was synthesized in our laboratory starting from mannitol-diacetonide through three or four step organic reactions. This new HPLC-assay procedure was successfully applied to deer antler extracts with good dose-dependent calibration curves at the picomole level of gangliosides.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.11
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• pp.483-493
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• 2002

The damping ratio ${\xi}$ of the unit-step response of a second-order discrete system is a function of only the location of the closed-loop poles and is not directly related to the location of the system zero. However, the peak overshoot of the response is the function of both the damping ratio ${\xi}$ and an angle ${\alpha}$, which is the phasor angle of the damped sinusoidal response and is determined by the relative location of the zero with respect to the closed-loop poles. Therefore, if the zero and the open-loop poles are relatively adjusted, through pole-zero cancellation, to maintain the desired (or designed) closed-loop poles, the damping ratio ${\xi}$ will also be maintained, while the angle ${\alpha}$ changes. Accordingly, when the closed-loop system poles are fixed, the peak overshoot is considered as a function of the angle ${\alpha}$ or the system zero location. In this paper the effects of the relative location of the zero on the system performance of a second-order discrete system is studied, and a design method of digital compensator which achieves a minimum peak overshoot while maintaining the desired system mode and the damping ratio of the unit step response is presented.

• Bulletin of the Korean Chemical Society
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• v.24 no.12
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• pp.1819-1826
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• 2003

In connection with the studies for developing new enzymes that could be useful in organic synthesis, practical preparation of racemic and enantiopure forms of ${\gamma}$-hydroxy-${\alpha}$-keto acids has been successfully achieved. For racemic form of ${\gamma}$-hydroxy-${\alpha}$-keto acids, indium-mediated allylation of aldehydes with 2-(bromomethyl)acrylic acid has been employed as a key step. Oxidative cleavage of the thus formed 2-methylenebutyrolactones provided the desired ${\alpha}$-ketobutyrolactones. Enzymatic resolution of the ${\gamma}$-hydroxy-${\alpha}$-methylene esters provided the desired${\gamma}$-hydroxy-${\alpha}$-methylene acids which were successfully converted to ${\gamma}$-hydroxy-${\alpha}$-ketobutyrolactones in optically pure forms.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.135-137
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• 1999

For the synthesis of new anti-inflammatory agents as indol derivatives, we have synthesized ${\alpha}$-benzoyl-1-ethyl-1,3,4,9-tetrahydro-8-ethyl-9-(N-benzoyl)pyrano[3,4-b]indole-1-acetic acid methyl ester. It was a new method for ${\alpha}$-substituted etodolac carboxylic acid. The synthetic process was composed of four steps, and 7-ethylindole and oxalyl chloride were used as starting materials. The third step, cyclization was carried out by addition of borontrifluoride diethyl etherate in 66% yield. The step of reduction and cyclization were simplified successfully. The final product, ${\alpha}$-benzoyl-1-ethyl-1,3,4,9-tetrahydro-8-ethyl-9-(N-benzoyl)pyrano[3,4-b]indole-1-acetic acid methyl ester was obtained in 66% yield by the reaction of methyl 1,8-dimethyl-1,3,4,9-tetrahydropyrano[3,4-b]indole-1-acetate (etodollic acid methyl ester) and benzoyl chloride.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.2
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• pp.246-255
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• 1996

To develop a natural antioxidative peptide, the gelatin was extracted from fish (Yellowfin sole) skin by hot $water(50^{\circ}C)$ extraction method and hydrolyzed with Alcalase, pronase and collagenase through a continuous 3-step membrane reactor. Each step enzymatic hydrolysates were determined the antioxidative activity and their synergistic effects, compared with $\alpha-tocopherol$ and butylated hydroxytoluene (BHT). Also, we tried to investigate the antioxidative disposition of peptide which was successfully separated by gel filtration, ion-exchange chromatography, and HPIC in cultured rat hepatocytes intoxicated with tert-butyl hydroperoxide (TBHP). Second step enzymatic hydrolysate (SSEH) among all hydrolysates and $\alpha-tocoperol$ was showed the strongest antioxidative activity. The optimum concentration of antioxidative activity for SSEH was $1\%(w/w)$ in linoleic acid. The synergistic effects were increased in using the hydrolysate with tocopherol and BHT. In the presence of the peptide isolated from SSEH, supplemented hepatocytes exposed to TBHP showed that delayed cell killing and decreased significantly the lipid peroxidation, compared with hepatocytes not cultured with isolated peptide.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.11a
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• pp.34-37
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• 1992

In this paper, the $(SrPb)(CaMg)TiO_3$-xBi_2O_3{\cdot}3TiO_2$ ceramics with paraelectric properties were fabricated by the mixed oxide method. In order to investigate the behavior of charged particles, the characteristics of electrical conduction and thermally stimulated current were measured respectively. As a result on characteristics of the electrical conduction, the leakage current was increased as measuring temperature was increased. At room temperature, the conduction current was divided into the three steps as a function of DC electric field. The first step was Ohmic region due to ionic conduction, below 15[kV/cm]. The second step was showed a saturation which seems to be related to a depolarizing field occuring in field-enforced ferroelectric phase, between 15[kV/cm] and 40[kV/cm]. The third step was attributed to Child's law related to spare charge which injected from electrode, above 40[kV/cm]. Thermally stimulated currents(TSC) spectra with various biasing fields exhibited three distinguished peaks that were denoted as ${\alpha}$, ${\alpha}'$ and ${\beta}$ peak, each of which appeared at nearby -30, 20 and 95[$^{\circ}C$] respectively. It is confirmed that the a peak was due to trap electron trapped in the grainboundary, and ${\alpha}'$ peak that was observed above only 1.5[kV/mm] was attributed to field-enforced ferroelectric polarization. The origin of ${\beta}$ peak was identified as ion migration which caused the degradation.

• The Korean Journal of Physiology
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• v.21 no.1
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• pp.47-58
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• 1987

It has been reported that the luteal function may be regulated by the intracellular $Ca^{++}$ level which may be adjusted partially by the high affinity $Ca^{++}-ATPase$ in luteal cell membranes. Then, one may expect that luteotropic and/or luteolytic agents, such as gonadotropins, prostaglandin $F_{2{\alpha}}\;(PGF_{2{\alpha}})$ and ouabain, affect the intracellular $Ca^{++}$ level. In this present study, therefore, we examined the effects of luteinizing hormone (LH, or human chorionic gonadotropin, hCG), $PGF_{2{\alpha}}$ and ouabain on the kinetic properties of the high affinity $Ca^{++}-ATPase$ in light membrane, heavy membrane, and microsomal fractions from the highly luteinized ovary. LH (or hCG) increased the affinity and the Vmax for $Ca^{++}$ both in light membrane and heavy membrane. $PGF_{2{\alpha}}$ increased the Vmax in light membrane and decreased the Km in heavy membrane for $Ca^{++}$ at low concentration $(5\;{\mu}g/ml)$. At higher concentration, however, $PGF_{2{\alpha}}$ oppositly affected on kinetic properties, that shown at low concentration. Ouabain, a potent inhibitor of $Na^+-K^+-ATPase$, increased the Km at high concentration $(10^{-4}\;M)$, however, decreased the Vmax for $Ca^{++}$ in light membrane at low concentration $(10^{-6}\;M)$. Also, ouabain increased the Km for $Ca^{++}$ in heavy membrane without changes in the Vmax at both concentrations. It seems that LH and low dose of $PGF_{2{\alpha}}$ increase the intracellular $Ca^{++}$ level and cause in activation of $Ca^{++}-ATPase$, however, higher dose of $PGF_{2{\alpha}}$ and ouabain inhibit directly $Ca^{++}-ATPase$ activity and result in increase in intracellular $Ca^{++}$ level. According to the above results, we suggest that luteotropic and/or luteolytic agents regulate the luteal progesterone $(P_4)$ production through two different pathways; one is cyclic adenosine monophosphate (cAMP)-dependent and another is $Ca^{++}-dependent$. Intracellula. $Ca^{++}$ level regulated by the high affinity $Ca^{++}-ATPase$ may affect both pathways in a time-dependent fashion. LH (or hCG) acts on the luteal $P_4$ production via both pathways. The initial step is $Ca^{++}$ dependent, and the late step is cAMP dependent. $PGF_{2{\alpha}}$ and ouabain increase the intracellular $Ca^{++}$ concentration so that basal luteal $P_4$ production is increased and LH-stimulated $P_4$ production is inhibited by the inhibiting LH-dependent adenylate cyclase activity.

• Geotechnical Engineering
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• v.14 no.2
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• pp.55-66
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• 1998

The purpose of this paper is to formulate and apply the stability analysis of toppling failure by considering the variation of discontinuity characteristics, slope geometry, and loading conditions. The stability condition on toppling failure of rock slope is mainly iuluenced by the dip angle $\alpha_B$ and H/t ratio. In order to check toppling failures in design, the stability charts composed of dip angle $\alpha_B$ versus H/t ratio have been constructed in the paper. In general, smaller dip angle $\alpha_B$ and smaller dip angle $\alpha_B$ and smaller H/T ratio give safer condition. The suggested curves change rapidly at the chitical point around the sone, H/t=4~6. The stable zone in stability charles becomes smaller due to step angle $\data$.

• Transactions of Materials Processing
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• v.11 no.5
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• pp.447-456
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• 2002

A study has been made to investigate the boundary sliding and its accommodation mode with respect to the variation of $\alpha$$_2$/$eta$ volume fraction during superplastic deformation of two-phase Ti$_3$Al-xNb intermetallics. Step strain rate and load relaxation tests have been performed at 950, 970 and 99$0^{\circ}C$ to obtain the flow stress curves and to analyze the deformation characteristics by the theory of inelastic deformation. The results show that the grain matrix deformation and boundary sliding of the three intermetallics containing 21, 50 and 77% in $eta$ volume fractions are well described by the plastic deformation and viscous flow equations. Due to the equal accommodation of both $a^2$ and $\beta$ phases, the accommodation modes for fine-grained materials are in good agreement with the iso-strain rate models. The sliding resistance analyzed for the different boundaries is the lowest in the $\alpha$$_2$/$\alpha$$_2$ boundary, and increases in the order of $\alpha$$_2$/$\alpha$$_2$<< $\alpha$$_2$/$\beta$ = $\beta$/$\beta$, which plays an important role in controlling the superplasticity of the alloys with the various $\alpha$$_2$/$\beta$ phase ratio.

• Journal of Microbiology and Biotechnology
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• v.5 no.5
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• pp.257-263
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• 1995

As a first step for developing Lactobacillus strains capable of fermenting starch directly, the $\alpha$-amylase gene (amyL) from Bacillus licheniformis (Kim et al., 1988. Kor. J. Appl. Microbiol. Bioeng. 16: 369-373) was introduced into Lactobacillus casei strains and the level of $\alpha$-amylase expression in transformants was examined. 3 kb EcoRI fragments encompassing amyL were subcloned into the suitable lactococcal cloning vectors (pSA3, pMG36e, and p1L2530) and then recombinant plasmids were introduced into E. coli and L. casei strains by electroporation. Only one recombinant plasmid, $pIL2530\alpha$ was able to transform few L. casei strains tested at low efficiencies. The transformation efficiencies with the plasmid into L. casei YIT 9018 and L. casei A Tee 4646 were less than $10^2/\mu$ g pIL2530\alpha$. The level of amylase activities in L. casei was five to ten-fold lower than that in E. coli cells. $p1L2530\alpha$ was stably maintained in Lactobacillus strains in the presence of Em (5 $\mu $g/ml) but without antibiotic selection, it was unstable so more than 95$%$ of cells lost plasmids after a week of daily subculturing.