• The Journal of Korean Medicine
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• v.25 no.4
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• pp.1-7
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• 2004

Objective : This study was designed to examine the effects of orally administered Prunus persica water extract (PPE), which is used as herbal medicine, for treatment of Yu Xue (stasis of blood) and tacrine on the basal concentration of extracellular acetylcholine in the hippocampus of rats. Methods: To investigate the effects of PPE and tacrine on concentration of extracellular acetylcholine in the hippocampus of rats, the microdialysis technique, under the same experimental conditions, was used. And we used male Wistar rats which were 7 weeks of age and 210-290 g. PPE was extracted with boiling water, and the rats were anesthetized with pentobarbital Na. Their skulls were exposed and a hole was drilled for implantation of a microdialysis probe. In order to increase the recovery of acetylcholine, a probe with a long membrane was used. One day after surgery, the microdialysis probe was perfused with Ringer's solution at a flow rate of 1.5 l/min. The acetylcholine concentration in dialysis samples was measured by high-performance liquid chromatography (HPLC) with electrochemical detection. AChE activity was measured using the radiometric method, as described by Sherman. Results : The comparative effects of PPE and tacrine on hippocampal extracellular acetylcholine concentration was that these cholinesterase inhibitors produced dose-dependent increases in the extracellular acetylcholine concentration. And the effect of PPE and tacrine on rat brain AChE activity was that PPE produced maximal inhibition at 1 h after administration, when AChE activity was 44% of the intact level. AChE activity gradually recovered thereafter, and reached 78% of the intact level at 12 h after administration. Conclusion : In this study, PPE has a potent activity and a long-lasting effect on the central cholinergic system, in terms of the basal concentration of extracellular acetylcholine in the hippocampus and the AChE activity in the brain of rats. And oral administration of PPE increased dose-dependently the basal concentration of extracellular acetylcholine in the hippocampus of rats. PPE may be one of the more useful cholinesterase inhibitors for the treatment of Alzheimer's disease.

• Toxicological Research
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• v.32 no.3
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• pp.215-223
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• 2016

This study is to investigate the biological, biochemical and cytotoxic effects of puffer fish (Arothron stellatus) toxin extracts under in-vitro condition. Extracted toxins from various organs of puffer fish were purified by using active charcoal column, and Bio-gel-P2 column chromatography. The lethality of toxin was tested in crabs, which consists of neurotoxic compounds. The degree of the brine shrimp lethality assay was found directly proportional to the concentration of the toxin extracts, which was well supported by hemolytic assay. The experimental results suggested that the gonad was found higher toxins than the liver and muscles. The mortality rate of brine shrimp nauplii was increased with the raise of concentrations of toxin level. Among the different doses and time dependent cytotoxic effect of human cervical carcinoma (HeLa) cells were showed $4.0{\mu}g/mL$ of toxin, which was effectively inhibited cancer cell proliferation. HPLC and TLC analysis was revealed that the A. stellatus toxin contains tetrodotoxin (TTX), related compounds 4-epi TTX and anhydro-TTX. The present results suggested that the A. stellatus contain TTX as a major and anh-TTX as a minor toxin. It could be the potential candidate in the field of anticancer drug discovery against human cervical cancer cells. The present data is confirming that the puffer fish toxin as an interesting source of novel bioactive natural compounds with potent applications in pharmacology.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.3
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• pp.309-316
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• 2015

A state-based peridynamic model is able to describe a general constitutive model from the standard continuum theory. The response of a material at a point is dependent on the deformation of all bonds connected to the point within the nonlocal horizon region. Therefore, the state-based peridynamic model permits both the volume and shear changes of the material which is promising to reproduce the complicated dynamic brittle fracture phenomena, such as crack branching, secondary cracks, cascade cracks, crack coalescence, etc. In this paper, the two-dimensional state-based peridynamic model for a linear elastic plane stress solid is employed. The damage model incorporates the energy release rate and the peridynamic energy potential. For brittle glass materials, the impact of the crack-parallel compressive stress waves on the crack branching pattern is investigated. The peridynamic solution for this problem captures the main features, observed experimentally, of dynamic crack propagation and branching. Cascade cracks under strong tensile loading and secondary cracks are also well reproduced with the state-based peridynamic simulations.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.4
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• pp.2503-2508
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• 2013

Histone deacetylation mediated by histone deacetylases (HDACs) has been reported as one of the epigenetic mechanisms associated with tumorigenesis. The poor responsiveness of anticancer drugs found with cholangiocarcinoma (CCA) leads to short survival rate. We aimed to investigate mRNA expression of HDACs class I and II, and the effect of HDAC inhibitors, suberoylanilide hydroxamic acid (SAHA) and valproic acid (VPA), in CCA in vitro. Expression of HDACs was studied in CCA cell lines (M213, M214 and KKU-100) and an immortal cholangiocyte (MMNK1) by semi-quantitative reverse transcription-PCR. SAHA and VPA, as well as a classical chemotherapeutic drug 5 -fluorouacil (5-FU) were used in this study. Cell proliferation was determined by sulforhodamine assay. $IC_{50}$ and $IC_{20}$ were then analyzed for each agent and cell line. Moreover, synergistic potentional of VPA or SAHA in combination with 5-FU at sub toxic does ($IC_{20}$) of each agent was also evaluated. Statistic difference of HDACs expression or cell proliferation in each experimental condition was analyzed by Student's t-test. The result demonstrated that HDACs were expressed in all studied cell types. Both SAHA and VPA inhibited cell proliferation in a dose-dependent manner. Interestingly, KKU-100 which was less senstitive to classical chemotheraoeutic 5-FU was highly was sensitive to HDAC inhibitors. Simultaneous combination of subtoxic doses of HDAC inhibitors and 5-FU signiicantly inhibited cell proliferation in CCA cell lines compared to single sgent treatment($P{\leq}0.01$), while sequentially combined treatments were less effective. The present study showed inhibitory effects of HDACIs on cell proliferation in CCA cell lines, with synergistic antitumor potential demonstrated by simultaneous combination of VPA or SAHA with 5-FU, suggesting a novel alternative therapeutic strategy in effective treatment of CCA.

• Journal of Korean Society on Water Environment
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• v.26 no.2
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• pp.349-355
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• 2010

Electroflotation (EF) was conducted for activated sludge thickening to investigate the effects of sludge SVI (sludge volume index) and chemical conditioning. Return sludge samples were used for the experiment, which were collected from municipal wastewater treatment plants. The performance of sludge thickening was significantly dependent on sludge SVI. For the sludges with SVI values in a range from 50 to about 150 mL/g, the maximum float content decreased rapidly from 8.4 to 3.5% and flotation compressibility followed the same pattern. In cases of sludges with SVI higher than 150 mL/g, those results showed low content levels without large changes. Gas/solids ratio tended to increase with an increase in SVI. When polyelectrolyte was added into sludges for the conditioning, compressibility increased up to 75% and gas/solids ratio was reduced up to about 35% under the condition of microbubble production rate of 530 mL/h, however, there was no consistent effect of chemical conditioning on the maximum float solids content; some cases were positive but the others negative. It was expected that the optimum dose of electrolyte depends on sludge SVI and an excessive chemical dose causes a performance deterioration of flotation thickening.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.9
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• pp.859-869
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• 2015

In this study, we analyze the problem of wedge cracks, which are geometrically unsymmetrical in transversely piezoelectric materials. A single concentrated antiplane mechanical load and inplane electrical load are applied at the point of the wedge surface, while one concentrated antiplane load is applied at the crack surface. The crack surfaces are considered as permeable thin slits, where both the normal component of electric displacement and the electric potential are assumed to be continuous across these slits. Using Mellin transform method, the problem is formulated and the Wiener-Hopf equation is derived. By solving the equation, the solution is obtained in a closed form. The intensity factors of the stress and the electric displacement are obtained for any crack length as well as inclined and wedge angles. Based on the results, the intensity factors are independent of the applied electric loads. The electric displacement intensity factor is always dependent on that of stress intensity factor, while the electric field intensity factor is zero. In addition, the energy release rate is computed. These solutions can be used as fundamental solutions which can be superposed to arbitrary electromechanical loadings.

• Journal of Society of Preventive Korean Medicine
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• v.17 no.3
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• pp.165-176
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• 2013

Objective : The purpose of this study was to establish the simultaneous analysis for six compounds in Gumiganghwal-tang (GMGHT, Jiuweiqianghuo-tang) and to investigate the anti-atherosclerotic effects of GMGHT in vitro. Methods : The column for separation of six compounds was used Luna $C_{18}$ column and maintained at $40^{\circ}C$. The mobile phase for gradient elution consisted of two solvent systems, 1.0% acetic acid in water and 1.0% acetic acid in acetonitrile. The analysis was carried out at a flow rate of 1.0 mL/min with pothodiode array (PDA) detection at 254, 280, and 320 nm. The injection volume was 10 ${\mu}L$. The antioxidant activities of GMGHT were evaluated by measuring free radical scavenging activities on 2,2'-Azinobis-3-ethyl-benzothiazoline-6-sulfonic acid (ABTS) and 1-1-diphenyl-2-picrylhydrazyl (DPPH). The inhibitory effects on low-density lipoprotein (LDL) oxidation were evaluated by the formation of thiobarbituric acid relative substances (TBARS), relative electrophoretic mobility (REM), and fragmentation of apolipoprotein B (ApoB)-100. Results : Calibration curves were acquired with $r^2{\geq}0.9998$. The contents of liquiritin, ferulic acid, baicalin, baicalein, glycyrrhizin, and wogonin in GMGHT were 1.784, 1.693, 37.899, 0.258, 1.869, and 0.034 mg/g, respectively. The GMGHT showed the radical scavenging activity in a dose-dependent manner. The concentration required for 50% reduction ($RC_{50}$) against ABTS and DPPH radicals were 72.51 ${\mu}g/mL$ and 128.49 ${\mu}g/mL$. Furthermore, GMGHT reduced the oxidation properties of LDL induced by $CuSO_4$. Conclusion : HPLC-PDA is considered as an available and convenient method for quality control and standardization of GMGH and GMGHT has potentials on anti-atherosclerosis by anti-oxidative effect and suppressive effect on LDL oxidation.

• Korean Chemical Engineering Research
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• v.51 no.2
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• pp.285-291
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• 2013

The effects of sensing materials, coating methods, diluent gases, and temperature have been studied in detail to make a quartz crystal microbalance based adsorption sensor system for detecting gases. In particular, sensor elements for detecting $NO_2$ and $SO_2$, that are known as major air pollutants, have been prepared by coating two different polymers, polypyrrole and poly(3,4-ethylenedioxythiophene). The sensor elements prepared in this work have high sensitivity and selectivity for $NO_2$ and $SO_2$ at ppm level concentrations. It was proven that the sensing characteristics and response rate of the sensing elements are highly dependent on the coating method and the loading mass of sensing materials.

• The Journal of Fisheries Business Administration
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• v.28 no.2
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• pp.1-18
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• 1997

The purpose of this study is to investigate empirically the characteristics of financial structure by using 76 fisheries corporations in Korea, and to suggest implications of the empirical results for government's financial policy for fisheries corporations. For the empirical test, we choose the following factors as the explanatory variables of cross-sectional regression analysis:firm-size(SIZE), collateral value of assets(TFATA), business risk(BRISK), growth(GROWTH), effective tax(ET), profitability(PROFIT). Two different debt ratios are used as dependent variables. One is defined as the ratio of total debt to total assets and the other is as that of long-term debt to total asset in terms of book value. The sample consists of 76 fisheries firms and sample period is 14 years from 1982 till 1995. From the results of cross-sectional regression analysis, the adjusted R$^2$values were high, 16∼79% and the overall F values indicated to be statistically significant. The results of cross sectional regression analysis show that the characteristics of financial structure fur fisheries corporations are as follows ; (1) Firm-size and collateral value of assets are the major factors of financial structure for fisheries corporations. That is, the larger firm-size the higher is debt ratio. This means that financial institutions conventionally lend more collateral loans with fixed assets like land, building rather than management capacities or credits. (2) To be consistent with a pecking-order theory, the higher is profitability the lower is debt ratio in fisheries corporations. (3) Corporations with high effective tax rate have lower financial leverage. Although the empirical results are inconsistent with traditional static trade-off theory, we think it would be attributed to government's various tax shelterings for fisheries which are likely to reduce tax shield effect of interests.

• Journal of the Korean GEO-environmental Society
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• v.21 no.12
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• pp.23-28
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• 2020

As a result of a suite of laboratory tests undertaken to suggest a rational method for the estimation of infiltration capacity, it is found that the infiltration rate tends to increase as the soil unit weight decreases while it tends to increase as the rainfall intensity increases. Comparative analyses for infiltration curves employing the reduction constant of initial infiltration capacity (α coefficient) that was suggested in this study has reasonably captured the time dependent variation of infiltration capacity. Consequently this study has presented an experimental model for the estimation of infiltration capacity to improve the Horton infiltration capacity curve that has been widely used for estimation of the infiltration capacity and amount of infiltration for its application to sandy soils.