• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2211-2213
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• 2005

Recently, the membrane technology has actively been applied to make generating water because the convention; chemical treatment technology for purifying water has caused second environmental pollution. In spite of its ecological advantages, this membrane technology has some drawbacks such as ease of membrane contamination, efficiency and running cost. The purpose of this research is reduction of membrane contamination by applying high voltage pulsed electric field to the water prior to its penetrating membrane.

• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1577-1582
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• 1999

Carrot juice inoculated with $2\;{\times}\;10^8\;cfu/mL$ of Escherichia coli was treated with pulsed electric fields(PEF) for the purpose of a development of new cold pasteurization processes. Inactivation of E. coli in carrot juice increased with increase in intensity of the electric field strength and treatment time. The cells were suspended at concentration of ca. $2\;{\times}\;10^8$ cells per ml. A reduction of 4D was obtained at 40 kv/cm and 256 exponential decay pulses at room temperature. Critical electric field strength(Ec) and treatment time(tc) needed for inactivation of E. coli were 11.74 kV/cm and $3.6\;{\mu}s$ at room temperature, respectively. The combination of PEF and thermal treatment inactivated E. coli more effectively. The reductions of up to 5.5D were observed when the carrot juice was treated with PEF of 22.5 kV/cm and $205\;{\mu}s$ at $50^{\circ}C$. PFF treatment did not effect in color, pH, $^{\circ}Brix$, titratable acidity and ${\alpha}-,\;{\beta}-carotene$ contents of carrot juice.

• The korean journal of orthodontics
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• v.24 no.4 s.47
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• pp.897-916
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• 1994

The biologic potential, which is different from the piezoelectric signals, relates tooth movement at least in part to changes in bone metaboliosm in bioelectric theory. The purpose of this experiment was to determine wheather the application of half sine-wave pulsed electromagnetic fields (HSPEMF) could increase both the rate and amount of orthodontic tooth movement. Forty-three male Hartley guinea pigs, weighting approximately 255g, were utilized in this study. The animals were 35 days old at the start of the study. Laterally directed orthodontic force was applied to the maxillary central incisors of 40 Hartley guinea pigs (20 experimental, 20 control). According to the amount of orthodontic force (6g, 12g), they were divided into two sub-groups (10 experimental I, 10 experimental II, 10 control I, 10 control II). During the experimental period, experimental animals were placed in plastic animal holders with their heads positioned in an area of uniform electromagnetic field. Control animals were placed in similar plastic holders that did not carry the electric apparatus. The results were as follows : 1. The application of a HSPEMF to the experimental groups significantly increase the final amount of orthodontic tooth movement observed over a 10-day experimental period. 2. The application of a HSPEMF to the experimental groups significantly increase the velocity of orthodontic tooth movement observed over a 10-day experimental period. 3. There was no significant difference in the final amount of orthodontic tooth movement at the fourth day to the eighth day, but there was significant difference in the final amount of orthodontic tooth movement at the nineth, tenth day during a 10-day experimental period. 4. After 10 days of HSPEMF exposure & orthodontic force, the experimental groups demonstrated more osteodasts in the pressure side than control groups.

• Korean Journal of Food Science and Technology
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• v.39 no.5
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• pp.506-514
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• 2007

In this study, carrot juice was treated with high voltage pulsed electric fields (PEF) and the changes in its physical and chemical properties during storage at $4^{\circ}C$ and $25^{\circ}C$ were investigated. The sterility fur bacteria, yeast and mold in carrot juice increased with increasing electric field strength and treatment temperature. While yeast and mold were completely inactivated at 65kV/cm with a treatment time of $200{\mu}s$ in a continuous PEF treatment system, bacteria were reduced by four log cycles. The results also showed that square wave pulse treatment was more effective for inactivating microorganisms than exponential decay pulse, and this effect was more apparent for carrot juice of lower pH. Although we observed significant changes in physical and chemical properties such as soluble solid content, pH, acidity, color, and carotene retention when the PEF treated samples were stored at the ambient temperature $(20^{\circ}C)$, no significant physical and chemical changes were found at the cold storage temperature $(4^{\circ}C)$ during 28 days of storage. The results indicate that the PEF treated carrot juice is appropriate for commercial refrigerated storage.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.720-726
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• 1999

High voltage pulsed electric fields (PEF) technology is a non-thermal technique which is applicable to extract useful components froms biological materials. This research suggested the possibility for extracting carotenoid pigments from Phaffia rhodozyma by PEF treatments. The yeast cell suspensions were treated with high voltage pulses in a recycled PEF treatment chamber which consists a pair of thin plates of stainless steel adhering to a small chamber with approximately $1{\sim}4\;mm$ gap. A 2.5 log reduction in survivability and more than 98% of electropermeabilization of the yeast cells could be achieved by PEF treatment for $300\;{\mu}s$ with an electric field of 30 kV/cm and pulse duration of $1\;{\mu}s$. When the yeast cell suspended in 0.01% NaCl solution were treated with PEF under various conditions, carotenoid pigments were not extracted. However, the PEF treatment of the yeast cell suspensions in 0.01% $CaCl_2$ solution, have positive effects on the extraction of carotenoid pigments ($27.3\;{\mu}g/g$ of dried yeast).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.121-121
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• 2010

As the industrial technology is getting higher, the pulsed power technology is required from various fields such as thermonuclear fusion energy sources, military applications, electric power distribution, and a variety of new specialized needs. This technology deals with the generation of very high power electromagnetic pulses through fast switching. We fabricated a pulsed power generator, named EMD pulse generator, by using Marx circuit with 200 kV high, 50 ns fast rise time. In this paper, we described about an effect of stray capacitance of coaxial Marx generator, EPG-AM200k, and a comparing the results of experiments and circuit analysis.

• Journal of Microbiology and Biotechnology
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• v.18 no.3
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• pp.545-551
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• 2008

When cultivated aerobically, Aspergillus niger hyphae produced extracellular glucoamylase, which catalyzes the saccharification of unliquified potato starch into glucose, but not when grown under anaerobic conditions. The $K_m\;and\;V_{max}$ of the extracellular glucoamylase were 652.3 mg/l of starch and 253.3 mg/l/min of glucose, respectively. In mixed culture of A. niger and Saccharomyces cerevisiae, oxygen had a negative influence on the alcohol fermentation of yeast, but activated fungal growth. Therefore, oxygen is a critical factor for ethanol production in the mixed culture, and its generation through electrolysis of water in an electrochemical bioreactor needs to be optimized for ethanol production from starch by coculture of fungal hyphae and yeast cells. By applying pulsed electric fields (PEF) into the electrochemical bioreactor, ethanol production from starch improved significantly: Ethanol produced from 50 g/l potato starch by a mixed culture of A. niger and S. cerevisiae was about 5 g/l in a conventional bioreactor, but was 9 g/l in 5 volts of PEF and about 19 g/l in 4 volts of PEF for 5 days.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.2
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• pp.79-85
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• 2001

A conventional electrolyzing cell has been made by an ion exchange membrane inbetween parallel plate electrodes. A low dc voltage is applied to the electrodes for electrolyzing and the efficiency is remained in low. in this study, a novel electrolyzing cell with a pair of slit-type third electrodes installed inbetween parallel plate electrodes has been proposed and investigated experimentally. And pulse power wa supplied to between each electrodes. This slit type of third electrodes can concentrate the strong electric fields at the every its edges to accelerate the electrolyzing powers, and to generate oxygen bubble discharges for generating oxidants. And moreover the slits eliminate the space charge limiting action and the temperature of the water by leaking out through the slits from electrolyzing region to outside of the main electrode region. As a result, it was found that a strong electorzed water of pH 2.8 and pH 10.5 and oxidants dissolved water of 1 [ppm] in acidic water were obtained with a tap water fed at the electric current of 2 [A], which however were several times higher oxidant and ion concentration quantity compared with the conventional cell.

• Transactions of Materials Processing
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• v.29 no.1
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• pp.49-54
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• 2020

The influence of electric current on the joining properties of aluminum and copper was investigated. Various pulsed electric current conditions were set to the joining specimens followed by pressure. The shear strength of the joint area between aluminum and copper was measured by the lab shear test. In addition, the microstructures of the joint area were observed through a field emission scanning electron microscope, energy dispersive X-ray, and electron backscatter diffraction. The mechanical properties of each phase in the joint region were measured by nano-indentation. As a result, it was confirmed that electrically assisted solid state joining of copper and aluminum could be applied in various industrial fields.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.46 no.3
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• pp.231-241
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• 2020

In this study in order to develop new approaches we investigated using high voltage pulsed electric fields (PEF) technology to reduce the risks, protect the phyto-constituents and improve skin biological activities. After preparing a Chaga mushroom (Inonotus obliquus) extracts pretreated with PEF, components measurement and skin efficacy evaluation were performed. As a result of the content measurement, the content of polysaccharide and polyphenol were higher in the order of extracts treated with 50 Hz and 25 Hz at 0.5 kV/cm, and the content of protein was the highest in extracts treated with 25 Hz at 0.5k V/cm. Similar to the results of the polyphenol measurements, extracts treated with 25 Hz and 50 Hz at 0.5 kV/cm showed leading DPPH scavenging ability. The cell protection effect against sodium dodecyl sulfate (SDS) and UVB was finest in extracts treated with 25 Hz at 0.5 kV/cm, which had the highest protein content. And the hyaluronic acid synthesis was leading in extracts treated with 50 Hz and 100 Hz at 0.5 kV/cm. Therefore, the active ingredient of the high-voltage PEF pre-treatment Chaga mushroom extract can be developed as a functional material with cell protection and moisturizing effect, and such green technology is expected to be used in various fields of cosmetics and material development.