• Journal of Korean Neurosurgical Society
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• v.38 no.6
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• pp.456-464
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• 2005

Objective : The authors investigated whether rotenone induces cellular death also in non-dopaminergic neurons and high concentration of potassium ion can show protective effect for non-dopaminergic neuron in case of rotenone-induced cytotoxicity. Methods : Neuro 2A cells was treated with rotenone, and their survival as well as cell death mechanism was estimated using 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium[MTT] assay, Lactate dehydrogenase[LDH] release assay, fluorescence microscopy, and agarose gel electrophoresis. The changes in rotenone-treated cells was also studied after co-treatment of 50mM KCl. And the protective effect of KCl was evaluated by mitochondrial membrane potential assay and compared with the effects of various antioxidants. Results : Neuro 2A cells treated with rotenone underwent apoptotic death showing chromosome condensation and fragmentation as well as DNA laddering. Co-incubation of neuro 2A cells with 50mM KCl prevented it from the cytotoxicity induced by rotenone. Intracellular accumulation of reactive oxygen species[ROS] resulting by rotenone were significantly reduced by 50mM KCl. Potassium exhibited significantly similar potency compared to the antioxidants. Conclusion : The present findings showed that potassium attenuated rotenone-induced cytotoxicity, intracellular accumulation of ROS, and fragmentation of DNA in Neuro 2A cells. These findings suggest the therapeutic potential of potassium ion in neuronal apoptosis, but the practical application of high concentration of potassium ion remains to be settled.

• Journal of Energy Engineering
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• v.23 no.1
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• pp.58-66
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• 2014

Catalytic gasification of a low rank coal- Inner Mongolian lignite has been carried out with carbon dioxide. The gasification reactions were performed in a thermogravimetric analyzer at temperatures of $600^{\circ}C$ to $900^{\circ}C$. The kinetic parameters were evaluated using three different gas-solids reaction models and the prediction ability of each model were compared. Among the models evaluated, the modified volumetric model was found to correlate best both the non-catalytic and catalytic gasification reactions. The theoretical models, homogeneous and shrinking-core models, were found to satisfactorily correlate gasification reactions for the non-catalytic and $FeSO_4$-catalyzed reactions. In case of alkali metal catalysts, the catalytic activity was mostly pronounced at a low temperature of $600^{\circ}C$ and observed to decrease by 50% as the temperature was increased to $700^{\circ}C$, and it remained nearly constant at temperature over $800^{\circ}C$. The order of catalytic activity was found to be: $K_2CO_3$ > $Na_2CO_3$ > $K_2SO_4$ > $FeSO_4$.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.8 no.6
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• pp.13-20
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• 2005

This study was conducted to examine the growth and physiological characteristics of Polystichum lepidocaulon native fern as affected by soil mixture as an environment modeled on habitate where was sunken-condition. 1. Polystichum lepidocaulon grew well sunken more than non-sunken condition. Under soil mixture of field soil : sand : leaf mold, Plant height, frond width, frond length, stipe length and ornamental value were increased compared with the other soil mixture. 2. Fresh and dry weight of fronds were higher with non-sunken than sunken condition. In sunken condition, fresh and dry weight were better with field soil : sand : leaf mold than the other soil mixture. 3. Number of spore fronds were increased with sunken condition. As sunken condition, sand : leaf mold was better than field soil : sand : leaf mold or leaf mold. 4. Photosynthetic rate, $CO_2$ absorption rate and water efficiency were higher with field soil : sand : leaf mold than that of sand : leaf mold or leaf mold. expect of stomatal conduction and $CO_2$ use efficiency.

• Journal of the Korean Chemical Society
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• v.30 no.1
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• pp.3-8
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• 1986

The investigation of the effect of solvent structure on the first-order solvolysis of cis-$[Co(en)_2ClNO_2]^+$ion has been extended to water + co-solvent mixtures where the co-solvents are glycerol, ethylene glycol, isopropyl alcohol and t-butyl alcohol. Rates of solvolysis have been evaluated by spectrophotometric method at temperature 25∼30$^{\circ}$C. The polarity of solvent has influence on the variation of rate constant. The non-linear plot of the rate constant in log scale versus $\frac{D-1}{2D+1}$ implies that change in solvent structure with composition plays an important role in determining the variation of rate constant. The linearity of the plot of the rate constant in log scale versus the Grundwald-Winstein Y factor confirms that the solvolysis is an Id-type process with considerable extension of the metal chloride bond in the transition state. In the Kivinen equation the slope of the plot of log k versus $log(H_2O)$ suggests that the solvolysis is also an Id-type process. The application of free energy cycle shows that the effect of solvent structure is greater in the transition state than in the initial state.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.44 no.2
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• pp.125-131
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• 2018

Ascorbic acid (Vitamin C) has been widely used in skin care formulations. Due to its remarkable effects on anti-oxidation, collagen biosynthesis and whitening, ascorbic acid is considered as an effectible anti-aging active ingredient. But, the instability problems of ascorbic acid in cosmetic formulation such as oxidation, browning and changes in smell is the difficult issue to be overcome for the application of high concentration of ascorbic acid. We tried to stabilize the ascorbic acid in non-aqueous liquid formulation that contains polyol solvent at first. The non-aqueous system was effectible to reduce oxidation. But, ascorbic acid was crystallized in the non-aqueous formulation at the low temperature below $5^{\circ}C$. We tried to develop way to stabilize the ascorbic acid in aqueous solutions to solve the crystallizing problem. In this study, we search the optimal ratio of antioxidant combination, such as zinc sulfate, glutathione and curcuma longa (turmeric) root extract. Formulations were stored at - $16^{\circ}C$, $5^{\circ}C$, $25^{\circ}C$, $40^{\circ}C$, $50^{\circ}C$ and cycle($5-40^{\circ}C$) (in incubator) for a period of eight weeks to investigate their stability. In the stability analysis, the test parameters consisted of color, scent, phase separation and sedimentation. Ascorbic acid stability was checked by HPLC analysis.

• Journal of Mechanical Science and Technology
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• v.20 no.2
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• pp.242-250
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• 2006

Detailed structures of the counterflow flames formed for different inlet fluid temperatures and different amount of additives are studied numerically. The detailed chemical reactions are modeled by using the CHEMKIN-II code. The discrete ordinates method and the narrow band based WSGGM with a gray gas regrouping technique (WSGGM-RG) are applied for modeling the radiative transfer through non-homogeneous and non-isothermal combustion gas mixtures generated by the counterflow flames. The results compared with those obtained by using the SNB model show that the WSGGM-RG is very successful in modeling the counterflow flames with non-gray gas mixture. The numerical results also show that the addition of $CO_2\;or\;H_2O$ to the oxidant lowers the peak temperature and the NO concentration in flame. But preheat of fuel or oxidant raises the flame temperature and the NO production rates. $O_2$ enrichment also causes to raise the temperature distribution and the NO production in flame. And it is found that the $O_2$ enrichment and the fuel preheat were the major parameters in affecting the flame width.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.429-430
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• 2011

This paper presents a simple and cost-effective stand-alone rapid battery charging system of 30kW for electric vehicles. The proposed system mainly consists of active front-end rectifier of neutral point clamped 3-level type and non-isolated bi-directional dc-dc converter of multi-phase interleaved half-bridge topology with coupled inductors. The charging system is designed to operate for both lithium-polymer and lithium-ion batteries. The complete charging sequence is made up of three sub-interval operating modes; pre-charging mode, constant-current mode, and constant-voltage mode. The pre-charging mode employs the staircase shaped current profile to accomplish shorter charging time while maintaining the reliable operation of the battery. The proposed system is able to reach the full-charge state within less than 16min for the battery capacity of 8kWh by supplying the charging current of 67A. The optimal discharging algorithm for Vehicle to the Grid (V2G) operation has been adopted to maintain the discharging current of 1C. Owing to the simple and compact power conversion scheme, the proposed solution has superior module-friendly mechanical structure which is absolutely required to realize flexible power expansion capability in a very high-current rapid charging system.

• Korea-Australia Rheology Journal
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• v.17 no.2
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• pp.87-95
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• 2005

In this study, we performed RTD measurement at the die exit of co-rotating twin-screw extruder using a non-destructive ultrasonic device. The ultrasonic device was attached at slit die and was composed of a steel buffer rod and 10 MHz longitudinal piezoelectric ultrasonic transducer. This in-line ultrasonic monitoring method is based on the ultrasonic response of $CaCO_3$ filled in polymer. The RTD is evaluated by variation of ultrasonic attenuation with time caused by change of the tracer concentration during extrusion. The ultrasonic tracer, pellet type of compounded $CaCO_3$ in polymer was used in this study. The effects of tracer concentration on RTD and flow patterns were studied. Evaluation for the residence functions at different screw speeds, feeding rates and screw configurations were also carried out.

• Korean Journal of Environmental Agriculture
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• v.38 no.4
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• pp.245-253
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• 2019

BACKGROUND: Weathering of bottom ash (BA) might induce change of its surface texture and pH and affect physical and chemical properties of soil associated with greenhouse gas emission, when it is applied to the arable soil. This study was conducted to determine effect of weathering of BA in mitigating emission of greenhouse gases from upland soil. METHODS AND RESULTS: In a field experiment, methane (CH₄), carbon dioxide (CO₂), and nitrous oxide (N₂O) emitted from the soil was periodically monitored using closed chamber. Three month-weathered BA and non-weathered BA were applied to an upland soil at the rates of 0, 200 Mg ha^-1. Maize (Zea mays L.) was grown from July 1_st to Oct 8_th in 2018. Both BAs did not affect cumulative CH₄ emission. Cumulative CO₂ emission were 23.1, 19.8, and 18.8 Mg/ha/100days and cumulative N₂O emission were 35.8, 20.9, and 17.7 kg/ha/100days for the control, non-weathered BA, and weathered BA, respectively. Weathering of BA did not decrease emission of greenhouse gases significantly, compared to the weathered BA in this study. In addition, both BAs did not decrease biomass yields of maize. CONCLUSION: BA might be a good soil amendment to mitigate emissions of CO₂ and N₂O from arable soil without adverse effect on crop productivity.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2003.04a
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• pp.123-123
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• 2003

In order to study gene expression transcribted during the embryo development, we constructed a cDNA library of embryogenic callus induced from cotylendon of Korean ginseng and generated expressed sequence tags (ESTs) of 3,359 clones randomly selected. The ESTs could be clustered into 1,910 (59.1%) non-redundant groups. Similarity search of the non-redundant ESTs against public non-redundant databases of both protein and DNA indicated that 2,217 groups show similarity to genes of known function. These ESTs clones were divided into eighteen categories depending upon gene function. Most abundant transcripts were ribosomal protein small subunit 28kDa(40), tumor-related protein(35), metallothionein (31), small heat-shock protein class 18.6K(24), and cyclophilin(20). There are no useful informations of gene expression during the embryo development in Korean ginseng. These results could help to understand the embryo development in Korean ginseng.