• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.145-146
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• 2012

• Journal of the Korean Society of Safety
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• v.17 no.3
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• pp.81-89
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• 2002

The runaway reaction was analyzed experimently and theoretically at the batch styrene suspension polymerization process. In the experiments, the reaction temperature with time was measured at various experimental conditions. According to the experimental results, the risk of the runaway reaction was increased with increasing the ratio of the monomer(styrene, M) to the dispersion medium(water, W), the concentration of the initiator(BPO), and the monomer mass, respectively. And simulation results showed that the runaway reaction was significantly affected by the reaction rate constant of the propagation and that the phenomena of the runaway reaction occurred at about 70% conversion. Also, we found that the runaway reaction did not occur under the operating condition of below 0.5 for M/W, approximate 3 wt% BPO, and below 75$^{\circ}C$ for the cooling temperature.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.11
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• pp.66-75
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• 2007

To prevent an insulator failure, an automatic cleaning and inspection robot was developed for suspension insulator strings. The robot autonomously moves along the insulator string using the clamps installed on its two moving frames. Especially, unlike the existing cleaning robots using jets of water, the robot system adopts a dry cleaning method using rotating brushes and a circular motion guide. In addition, a mechanized brush bristles and a voltage-balancing contactor are devised to increase cleaning efficiency and to prevent arc generation under live-line conditions, respectively. We confirmed its effectiveness through experiments.

• Membrane Journal
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• v.2 no.2
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• pp.104-111
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• 1992

A curved channel duct is designed, built and used specifically to produce Dean vortices as a result of flow around a $180^{\circ}C$ curve. We present evidence using optical reflection of the existmace of the vortices in the curved section and following flat section. Also, three different feed soludons(DI water, a monodispersed styrene-divinyl-benzene latex particle suspension and a yeast suspension) were used to determine the effectiveness of Dean instabilities to destabilize polarization layers. For each suspension, the flux data were compared as a function of time for flow conditions with and without Dean vortices, for a $0.2{\mu}m$ microfiltration membrane. Any permeation flux improvement was not sustained for $2.0De_c$ due to the vortex-decay in the flat section after the curved channel, but a 15~30% permeation improvement was obtained for $3.8De_c$.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.5
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• pp.666-672
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• 2004

Granular media filtration is used almost universally as the last particle removal process in conventional water treatment plants. Therefore, superb particle removal efficiency is needed during this process to ensure a high quality of drinking water. However, every particle can not be removed during granular media filtration. Besides the pattern of particle attachment is different depending on physicochemical aspects of particles and suspension. Filtration experiments were performed in a laboratory-scale filter using spherical glass beads with a diameter of 0.55 mm as collectors. A single type of particle suspension (Min-U-Sil 5) and pH control was used to destabilize particles. The operating conditions were similar to those of standard media filtration practice: a filtration velocity of 5 m/h. More favorable particles, i.e., particles with smaller surface charge, were well attached to the collectors especially during the early stage of filtration. This selective attachment of the lower charged particles caused the zeta potential distribution (ZPD) of the effluent to move to a more negative range. On the other hand, the ZPD of the effluent did not keep moving from less negative to more negative during the later stages of filtration, and this result was thought to be caused by two reasons: ripening effects and the detachment of flocs.

• Journal of Oriental Neuropsychiatry
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• v.20 no.3
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• pp.49-64
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• 2009

Objectives : The water and methanol extracts of Aconitum carmichaeli(Aconiti Tuber Preparat) were investigated for their anti-depressant effects. Methods : In this study, reserpine-induced hypothermia test, tail suspension test and hot plate test. Additionally, the brain monoamine oxidase activity was determined in vivo. Results: In the reserpine-induced hypothermia test, both extracts suppressed the fall of body temperature compared to the control group in a dose-dependent manner, suggesting the inhibition on hypothermia. In the tail suspension test, the methanol extract dose-dependently reduced the duration of immobility by 28.4% at a dose of 1 g/kg compared to control group, which is more effective than the water extract. In the hot plate test, the water extract and methanol extract increased the jump latency time compared to the control group, showing the inhibition rate of 198% and 182%, respectively, at a dose of 1 g/kg. Methanol extracts potently inhibited the brain monoamine oxidase activity in an in vivo assay compared to the control group, showing 84.6% inhibition, but the water extract revealed very weak activity. Conclusions : Above results suggested that the extract of Aconitum carmichaeli can be useful for the prevention and treatment of depression.

• Journal of Korean Society on Water Environment
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• v.36 no.3
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• pp.185-193
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• 2020

Bimodal flocculation describes the aggregation and breakage processes of the flocculi (or primary particles) and the flocs in the water environment. Bimodal flocculation causes bimodal size distribution with the two separate peaks of the flocculi and the flocs. Extracellular polymeric substances and ionic species common in the water environment increase the occurrence of bimodal flocculation and flocculi-floc size distribution, under the flocculation mechanisms of electrostatic attraction and polymeric bridging. This study investigated bimodal flocculation and flocculi-floc size distribution, with respect to the extracellular polymeric substance concentration and ionic strength in the kaolinite-containing suspension. The batch flocculation tests comprising 0.12 g/L of kaolinite showed that the highest flocculation potential occurred at the lowest xanthan gum (as extracellular polymeric substances) concentration, under all the ionic strengths of 0.001, 0.01, and 0.1 M NaCl. Also, it was important to note that the higher ionic strength resulted in the higher flocculation potential, at all the xanthan gum concentrations. The bimodal flocculation and flocculi-floc size distribution became apparent in the experimental conditions, which had low and intermediate flocculation potential. Besides the polymeric bridging flocculation, steric stabilization increased the flocculi mass fraction against the floc mass fraction, thereby developing the bimodal size distribution.

• Macromolecular Research
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• v.11 no.6
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• pp.518-522
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• 2003

We fabricated polymeric hollow spheres having macropores, which combine the advantageous properties of porous materials and hollow spheres. To fabricate such spheres, a polystyrene/methylmethacrylate solution was dispersed in water by vigorously stirring and then the suspension was quenched using liquid nitrogen. Water and methyl methacrylate present in the quenched suspension were readily sublimated by freeze-drying. Conclusively, the hollow-sphere structure and the macropores of its shell were created by the processes of liquid nitrogen-quenching and sublimation of methyl methacrylate domains within the shell, respectively.

• Korean Journal of Pharmacognosy
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• v.29 no.4
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• pp.360-364
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• 1998

To develop new elicitors inducing the high productivity of taxane derivatives, plant growth inhibitors, namely, maleic acid hydrazide, N-phosphomethyl glycine and succinic acid 2.2-dimethyl hydrazide, coconut milk and yeast extract were administrated in the cell suspension culture system of Taxus cuspidata, and the production of baccatin III were analysed. The effects of amino acid related with the biosynthesis of baccatin III were also examined in these culture system. As the results, a remarkable enhancement of baccatin III production was observed in the cultivation with coconut water and with maleic acid hydrazide.

• Journal of Environmental Science International
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• v.1 no.2
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• pp.93.1-104
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• 1992

Because of varied functions and characteristics, water soluble polymers have lone attracted much intrest in both academic and industrial fields, especially now in pollution problems such as wastewater treatment through ployrneric flocculants. In this regard, the main objective of this study is to synthesize polymeric floccuants containning hydrophobic group in presence of the potassium persulfate/sodium thiosulfate redox system and to estimate their flocculating ability on the kaolin suspension. In order to test the flocculating power of flocculant prepared on the kaolin suspension system, turbidity of the supernatant liquid, residence time, filtration rate of flocculated samples, have additionally been measured from the flocculation experiments and analysed In comparision with the theoretical background.