• Nuclear Engineering and Technology
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• v.35 no.1
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• pp.55-63
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• 2003

Threshold porosity above which fission gas release channels would be formed in the rim egion of high burnup UO$_2$ fuel was estimated by the Monte Carlo method and Hoshen-Kopelman algorithm. With the assumption that both rim pore and rim grain can be represented by cube, pore distribution in the rim was simulated 3-dimensionally by the Monte Carlo method according to porosity and pore size distribution. Then, using the Hoshen-Kopelman algorithm, the fraction of open rim pores interlinked to the outer surface of a fuel pellet was derived as a function of rim porosity. The simulation showed that porosity of 24-25% is the threshold above which the number of rim pores forming release channels increases very rapidly. On the other hand, channels would not be formed if the porosity is less than about 23.5%. This is consistent with the observation that, for porosity less than 23.5%, almost no fission gas is released in the rim. However, once the rim porosity reaches beyond 25%, extensive open paths would be developed and considerable fission gas release would start in the rim.

• Archives of Pharmacal Research
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• v.20 no.6
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• pp.555-559
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• 1997

The three different batches of an oral sustained release melatonin (MT) delivery system were prepared by aqueous-based fluid-bed coating of the sugar spheres for the evaluation of in vitro release characteristics and plasma concentration profiles in human subjects. The MT contents in 20% coated sugar spheres of three batches (B1, B2 and B3) were $3.3{\pm}0.08$, $2.4{\pm}0.1$ and $2.5{\pm}0.13$ mg per gram of coated sugar spheres, respectively. The release profiles of three different batches had a very similar fashion. However, the release profiles of three different batches had a very similar fashion. However, the release half-lives $(T_{50%})$ of MT from B1, B2 and B3 was $3.70{\pm}0.2$, $5.2{\pm}0.2$ and $4.9{\pm}0.07h$, respectively. Plasma concentration profiles of sustained release 0.2mg melatonin-loaded sugar spheres containing 10% immediate release melatonin in gelatin capsules (B1 and B2) were then evaluated in human subjects. The in vivo plasma concentration profies of the two batches (B1 and B2) were very similar each other and located between the physiological endogenous ranges. The time to reach the peak concentration $(T_max)$ was more advanced in case of B1 when compared to B2. However, there was no statistically significant difference in the maximum concentration $(C_max)$ and the area under the curve (AUC) between B1 and B2. The AUC of melatonin-loaded sugar spheres containing 10% and 20% immediate release MT in human subjects had a good linearity between dose and AUC, regardless of the fraction of immediate release MT, indicating the first order elimination process of MT within these doses. The current oral sustained release MT delivery system may be utilized to treat circadian rhythm disorders if it is proven to be more clinically useful when compared to immediate release MT.

• Journal of Ginseng Research
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• v.39 no.1
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• pp.54-60
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• 2015

Background: The present study was designed to prepare and find the optimum active preparation or fraction from Korea Red Ginseng inhibiting matrix metalloproteinase-13 (MMP-13) expression, because MMP-13 is a pivotal enzyme to degrade the collagen matrix of the joint cartilage. Methods: From total red ginseng ethanol extract, n-BuOH fraction (total ginsenoside-enriched fraction), ginsenoside diol-type-enriched fraction (GDF), and ginsenoside triol-type-enriched fraction (GTF) were prepared, and ginsenoside diol type-/F4-enriched fraction (GDF/F4) was obtained from Panax ginseng leaf extract. Results: The n-BuOH fraction, GDF, and GDF/F4 clearly inhibited MMP-13 expression compared to interleukin-$1{\beta}$-treated SW1353 cells (human chondrosarcoma), whereas the total extract and ginsenoside diol-type-enriched fraction did not. In particular, GDF/F4, the most effective inhibitor, blocked the activation of p38 mitogen-activated protein kinase (p38 MAPK), c-Jun-activated protein kinase (JNK), and signal transducer and activator of transcription-1/2 (STAT-1/2) among the signal transcription pathways involved. Further, GDF/F4 also inhibited the glycosaminoglycan release from interleukin-$1{\alpha}$-treated rabbit cartilage culture (30.6% inhibition at $30{\mu}g/mL$). Conclusion: Some preparations from Korean Red Ginseng and ginseng leaves, particularly GDF/F4, may possess the protective activity against cartilage degradation in joint disorders, and may have potential as new therapeutic agents.

• Journal of the Korean Society of Safety
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• v.28 no.3
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• pp.39-43
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• 2013

The present study has been conducted to investigate the fire combustion properties and fire behavior of an IEEE-383 qualified flame retardant cable. The reference reaction rate and reference temperature which are commonly used in pyrolysis model of fire propagation process was obtained by the thermo-gravimetric analysis of the cable component materials. The mass fraction of FR-PVC sheath abruptly decreased near temperature range of $250{\sim}260^{\circ}C$ and its maximum reaction rate was about $2.58{\times}10^{-3}$[1/s]. For the XLPE insulation of the cable, the temperature causing maximum mass fraction change was ranged about $380{\sim}390^{\circ}C$ and it has reached to the maximum reaction rate of $5.10{\times}10^{-3}$[1/s]. The flame retardant cable was burned by a pilot flame meker buner and the burning behavior of the cable was observed during the fire test. Heat release rate of the flame retardant cable was measured by a laboratory scale oxygen consumption calorimeter and the mass loss rate of the cable was calculated by the measured cable mass during the burning test. The representative value of the effective heat of combustion was evaluated by the total released energy integrated by the measured heat release rate and burned mass. This study can contribute to study the electric cable fire and provide the pyrolysis properties for the computational modeling.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.04a
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• pp.14-14
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• 2018

This Camptotheca acuminata Decne. (CA), belonging to Nyssaceae, is a deciduous tree. and has been used as Traditional Chinese medicine since ancient times. The CA produces camptothecin a natural indole alkaloid, and reported to have anti-cancer effects. But the studies on biological activities of CA leaves are insufficient. Therefore, this study confirmed various biological activities such as antioxidant, antidiabetic, anticancer, antiinflammatory and metabolism analysis by HPLC-MS/MS of CA leaves. The $RC_{50}$ values of DPPH radical scavenging activity of ethyl acetate fraction, n-Butanol fraction, methanol extraction, water fraction and n-Hexane fraction were $12.23{\pm}0.01$, $15.93{\pm}0.42$, $55.12{\pm}0.45$, $56.29{\pm}4.15$ and $427.29{\pm}6.13ug/mL$, respectively. The $IC_{50}$ values of ${\alpha}$-glucosidase inhibitory activity of ethyl acetate fraction, n-Butanol fraction, methanol extraction, n-Hexane fraction and water fraction were $24.29{\pm}0.14$, $47.86{\pm}0.45$, $54.23{\pm}1.21$ $466.76{\pm}2.21$ and $623.91{\pm}9.67ug/mL$, respectively. The nitric oxide release activity of n-Hexane fraction, methanol extraction, ethyl acetate fraction, water fraction and n-Butanol fraction were $31.49{\pm}5.74$, $29.79{\pm}0.71$, $26.89{\pm}0.71$, $8.24{\pm}5.83$ and $7.75{\pm}4.08%$ at 25 ug/mL, respectively. The anti-cancer activity of n-Hexane fraction, methanol extraction, ethyl acetate fraction, water fraction and n-Butanol fraction were $31.49{\pm}5.74$, $29.79{\pm}0.71$, $26.89{\pm}0.71$, $8.24{\pm}5.83$ and $7.75{\pm}4.08%$ at 25 ug/mL, respectively. The ethyl acetate fraction activities showed higher biological activities than other fractions. Thus, Additional studies were conducted using ethyl acetate fraction. Metabolite analysis was performed using a LCMS-8040 triple quadrupole mass spectrometer. As a result, Five compounds (1-5) were identified in the ethyl acetate fraction of the CA leave. The identification of these compounds was generated by the analysis of fragmentation methods of the negative and positive ion modes. Five compounds were identified as gallic acid (1), chlorogenic acid (2), isoquercetin (3), astragalin (4) and camptothecin (5). These results suggest that the CA leave can be used for functional materials.

• Journal of the Korean Society of Industry Convergence
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• v.18 no.2
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• pp.110-118
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• 2015

In this study, it is designed and used the test engine bed which is installed with turbocharger, and in addition to equipped using by oxygen adder. It has been controlled the oxygen volumetric fraction of intake air chrge, and supercharged flow rate into the cylinder of SI 4-stroke engine, and then, has been analyzed engine performance, combustion characteristics, and exhaust emission as analysis parameters. The tested parameters were the oxygen fraction and the variation of engine speed and air-fuel ratio.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.7
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• pp.469-475
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• 2014

The study investigated the physicochemical characteristics and the ecological risk of the Northport sediment in B city and the releasing properties of heavy metals into seawater during the resuspension also studied. The major components of the sediment are fine silt and clay which contains high organic matter and AVS (Acid volatile sulfide) and the ecological risk of the heavy metals in sediment also very high. The release rate of heavy metals into seawater was in order of Pb>>Cu>Cr>>Zn>Cd during the resuspension in a batch experiment, and the heavy metal release mainly attributed to the oxidation of metal sulfides. Heavy metals which came from easily oxidisable metal sulfides rapidly contaminated seawater within about 1.0 h of the sediment resuspension. The sulfide oxidation during the resuspension increased the residual fraction of heavy metals in the sediment, decreased the organic bound fraction, and changed the other fractions of heavy metals in the sediment. The release of heavy metals from the sediment during resuspension was affected by the resuspension time, the oxidation rate of metal sulfides and resuspended concentration of the sediment particle.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.7
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• pp.1357-1364
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• 2000

Our study was performed to evaluate the effect of leaching parameters including the physicochemical characteristics and the fractionated composition of heavy metals on the release of heavy metals in fly ash discharged from MSWI. Leaching parameters such as pH, CEC, particle size, and exchangeable fraction among the fractional composition classified by sequential extraction procedure are considered. The leaching rate of heavy metal released by KSLT method is largely dependent on the pH of fly ash. The effect of pH on the release of heavy metals is different from elements. It appears that the leaching rate of cadmium and copper decreases with increasing pH, while lead and zinc increases at the condition of neutral or strong alkali condition, which suggests that the leaching of heavy metals are limited by the solubility. It is found that the effect of CEC is similarly to that of pH, $D_{10}$ among the particle size of fly ash is negative correlated with the concentration of heavy metals leached by KSLT method. In the case of exchangeable fraction, the leaching rate of heavy metals is linearly correlated with the exchangeable fraction for the fly ash below 40 meq/l00g of CEC, but not related out of the range.

• Korean Journal of Plant Resources
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• v.31 no.1
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• pp.16-23
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• 2018

Paeonia japonica is a perennial flowering plant used in traditional medicine therapy. The purpose of this study was to investigate the effect of water extract and solvent fractions obtained from P. japonica on anti-oxidative, anti-thrombin, anti-invasive and pro-apoptotic activities in YD-10B cells, human oral squamous carcinoma cell line. Water fraction revealed the highest extraction yield at 11.44% (w/w). Anti-oxidative activity was the highest in ethyl acetate fraction (85.13%). In the thrombin inhibitory activity test, ethyl fraction was the highest, with a value of 87.54%. Release and activation of MMP-2/pro-MMP-2 ratio in thrombin-treated YD-10B cells were significantly inhibited in the ethyl acetate fraction. At a concentration of $120{\mu}g/m{\ell}$ water extract and solvent fractions of P. japonica inhibited cell proliferation in YD-10B cells except water fraction. Pro-apoptotic effect on human oral squamous carcinoma cell using the Bax/Bcl-2 ratio analysis was higher in water extract than other fractions. These findings suggest that the ethyl acetate fraction of P. japonica potentiates a promising antioxidant, anti-thrombin and anti-invasive agents.

• Journal of Energy Engineering
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• v.24 no.3
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• pp.61-66
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• 2015

Homogeneous charge compression ignition (HCCI) engine combines the combustion characteristics of a compression ignition engine and a spark ignition engine. HCCI engines take advantage of the high compression ratio and heat release rate and thus exhibit high efficiency found in compression ignition engines. In modern research, simulation has be come a powerful tool as it saves time and also economical when compared to experimental study. Engine simulation has been developed to predict the performance of a homogeneous charge compression ignition engine. The effects of compression ratio, cylinder pressure, rate of pressure rise, flame temperature, rate of heat release, and mass fraction burned were simulated. The simulation and analysis show several meaningful results. The objective of the present study is to develop a combustion characteristics model for a homogeneous charge compression ignition engine running with isooctane as a fuel and effect of compression ratio.