• Journal of Biosystems Engineering
• /
• 제35권2호
• /
• pp.100-107
• /
• 2010

This study was conducted to investigate the effects of electric current stimuli and high-voltage electric field treatments on brown rice germination. The brown rice stimulated by electrical current stimuli, functional electrical stimuli of a pulse type, and high-voltage electric field treatments were observed (Type I, II and III). Treatment Type I was a method of semi-soaking brown rice with electric current stimuli of 0.13 V/cm, 0.19 V/cm, and 0.25 V/cm into Petri-dishes for 72 hours. Type II was a method of semi-soaking brown rice with functional electrical stimuli of a pulse type(DC 1 V, 1 Hz, 5%, and duty cycles of 5%, 20%, and 35%) into Petri-dishes for 72 hours. Type III was a method of water-soaking with high-voltage electric field treatments for 60 hours. High-voltage electric field treatments at 15 kV/cm were also conducted for 2.5 min, 7.5 min, and 10 min, respectively. The germination rate and the sprout growth of brown rice germinated by electric current stimuli with 0.13 V/cm, 0.19 V/cm, and 0.25 V/cm were increased by about 10-15% compared with those of the control group. The germination rate and the sprout growth of brown rice germinated by functional electrical stimuli of pulse type(DC 1 V, 1 Hz, 5% duty cycle) were increased by about 10∼15% compared to those of the control group. Also, the best effective treatment among high-voltage electric field treatments was the 10 min group at 15 kV/cm. The germination rate and the sprout growth of brown rice germinated by this treatment of 10 min at 15 kV/cm were increased by about 10∼20% compared to those of the control group. The treatments of electric current stimuli and high-voltage electric field accelerated the germination rate and sprout growth of brown rice by about 10∼15% compared to those of the control group.

• Journal of Microbiology and Biotechnology
• /
• 제8권2호
• /
• pp.119-123
• /
• 1998

The feasibility of using combined treatments of electric field and chemical mutagen N-methyl-N'-nitro-N-nitroso-guanidine (NTG) for the strain improvement of Saccharomyces sp. in ethanol production was examined. The treatment of electric field alone resulted in no effect on the lethality of yeast cells under the conditions of this study. However, when the electric field was applied together to the treatment of yeast cells with NTG, the electric field increased the lethal effect and auxotrophic mutation rate of NTG. The combined treatment of electric field and NTG also increased the chances of. obtaining superior yeast strains for the ethanol production from tapioca. A higher number of improved clones was obtained by the combined treatments of electric field and NTG than by the NTG treatment alone. The best clone, NF 30-9, which was also obtained by the combined treatment, produced $11.07\%$ (w/v) ethanol from tapioca slurry containing 25% (w/v) reducing sugar while the parental strain produced 9.77% (w/v).

• 한국토양비료학회지
• /
• 제38권2호
• /
• pp.78-84
• /
• 2005

국내에서 자가 채종되는 양파종자의 품종, 종자의 함수량 및 종자크기가 발아율에 미치는 영향과 gibberellin, $KNO_3$ 및 $NaNO_3$ 등의 화학약품, 및 전기장과 자기장 처리가 발아율과 초기생육에 미치는 영향을 조사하였다. 종자의 품종에 따른 발아율의 변화는 거의 없었으나, 채종 후 저장 또는 건조정도에 따라 큰 차이를 나타내었다. 종자의 함수량이 10-15% 범위에서 발아율이 가장 높았으며, 대립종자보다는 중립과 소림종자의 발아율이 높게 나타났다. 화학약품을 처리한 종자의 발아율 GA < $NaNO_3$ < $KNO_3$ 순으로 높게 나타났다. $KNO_3$ 0.1%와 0.2% 처리로 최종발아율이 10-12% 증가하였으며, nitrate가 양파종자의 발아촉진 및 발아율 향상에 효과적인 것으로 나타났다. 전기장 또는 자기장 처리에 의해 양파종자의 발아율이 향상되었으며, 전기장 10 kV와 자기장 4 Gauss 처리시 각각 86%와 88%로 무처리구에 비해 10-12% 높았다. 또한 전기장과 자기장 처리로 양파종자의 초기생육은 향상되었으며, 파종 40일 후의 초장 및 생체중량이 무처리구에 비해 23-45% 증가되었다.

• 한국식품저장유통학회지
• /
• 제20권5호
• /
• pp.650-658
• /
• 2013

전기장의 세기 20 kV/cm, 펄스 폭 25 ${\mu}s$에서 펄스 빈도 35 Hz(40 kJ/L), 55 Hz(70 kJ/L), 72 Hz(100 kJ/L) 및 85 Hz(130 kJ/L)로 달리하여 투입 에너지를 기준으로 사과 착즙액의 PEF 연속처리 살균 효과를 분석한 결과 일반세균수은 초기 5.3 log CFU/mL에서 130 kJ/L의 에너지로 처리하였을 때 3.0 log CFU/mL로 감소하였고 효모 및 곰팡이는 초기 4.6 log CFU/mL에서 130 kJ/L의 에너지로 처리로 < $10^1$ CFU/mL 이하로 감소하였다. 그리고 대장균군수도 초기 4.7 log CFU/mL에서 130 kJ/L의 에너지 처리로 < $10^1$ CFU/mL 이하로 감소하였다. PEF 처리에 따른 가용성 고형분, 유리당 등에는 처리 조건에 따른 유의적 차이가 없었으며(p<0.05), 총 페놀함량, DDPH 및 FRAP 값은 처리조건에 따라 부분적으로 유의적인 감소를 보였지만 $65^{\circ}C$에서의 가열처리보다는 감소량이 작았다. 전기장 세기 20.0 kV/cm, 펄스 빈도 85 Hz, 펄스 폭 25 ${\mu}s$에서의 반복처리는 미생물 살균 효과가 제한적이었고 처리회수에 따라 총 페놀함량, DPPH 및 FRAP 값을 유의적(p<0.05)으로 감소시켰다.

• 한국식품과학회지
• /
• 제49권4호
• /
• pp.408-414
• /
• 2017

본 연구에서는 PEF 처리 시간과 전기장 세기가 증가할수록 주스 내 토착 미생물 저해 효과가 상승함을 알 수 있었고, 또한 처리 주스의 주입 온도를 높여 $40^{\circ}C$에서 PEF 처리했을 때 살균 효과가 높아짐을 확인하였다. 상온 PEF와 중온 PEF 처리 모두 감귤 주스와 당근 주스의 이화학적 영양학적 특성에 크게 영향을 주지 않으면서도 상업적 살균에 적합한 미생물 저해 효과를 보여주었다. 본 연구는 파일럿 규모의 PEF 처리 장비를 이용하여 감귤 주스와 당근 주스를 살균하지 않은 주스의 품질을 유지하면서 살균할 수 있음을 보여주었다. 처리 시간, 전기장 세기, 그리고 주입 온도의 조절을 통해 최소의 에너지 사용으로 품질 보존과 동시에 최대의 미생물 저해 효과를 얻는 PEF 살균 공정 최적화가 다양한 주스 제품에 대하여 이루어 질 수 있을 것으로 전망한다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제24권9호
• /
• pp.1314-1317
• /
• 2011

To evaluate the effects of pulsed electric field (PEF) application on scalder and chiller water on Campylobacter contamination, four different treatments under three different water conditions including hard scalder water ($55^{\circ}C$), soft scalder water ($45^{\circ}C$) and chiller water, were applied as follows: i) a control treatment with no salt and no electric treatment, ii) a PEF only treatment, iii) a PEF treatment with 0.5% salt water, and iv) a PEF treatment with 1% salt water treatment. The use of PEF in hard scalding water showed an effect of reducing Campylobacter when compared to the control during the 200 s timeframe. With the addition of salt, the intervention caused at least 5.81 log CFU/ml reduction of Campylobacter counts after 200 s of PEF exposure. Similar effects were observed under soft scalding conditions. Campylobacter reductions were evident under chilling conditions with up to 2.00 log for PEF only, 5.77 log for PEF+0.5% salt and 2.69 log for PEF+1% salt treatment in water. Therefore, the current PEF setting for the scalder and chiller water can be successfully used to reduce pathogenic loads of Campylobacter on broiler chicken carcasses, and further research may be necessary to apply it in the poultry processing industry.

• 한국재료학회지
• /
• 제17권3호
• /
• pp.173-178
• /
• 2007

Carbon nanotube cathodes(CNT cathodes) with a trench structure similar to gated structure of triode-type cathode were fabricated by a screen printing method using multi-walled carbon nanotubes. The effects of surface treatments on CNT cathodes were investigated for high efficiency field emission displays(FEDs). A liquid method easily removed the organic residue and protruded the CNTs. Field emission properties were measured by using a diode-type mode. The liquid method produced a turn-on field of $1.4V/{\mu}m$. The emission current density was measured about $3.1mA/cm^{2}$ at the electric field of $3V/{\mu}m$. The liquid method showed a high potential applicable to the surface treatment for triode-type FEDs.

• 한국축산식품학회지
• /
• 제35권6호
• /
• pp.800-806
• /
• 2015

We investigated the effects of a pulsed electric field (PEF) treatment on microbial inactivation and the physical properties of low-fat milk. Milk inoculated with Escherichia coli, Saccharomyces cerevisiae, or Lactobacillus brevis was supplied to a pilot-scale PEF treatment system at a flow rate of 30 L/h. Pulses with an electric field strength of 10 kV/cm and a pulse width of 30 µs were applied to the milk with total pulse energies of 50-250 kJ/L achieved by varying the pulse frequency. The inactivation curves of the test microorganisms were biphasic with an initial lag phase (or shoulder) followed by a phase of rapid inactivation. PEF treatments with a total pulse energy of 200 kJ/L resulted in a 4.5-log reduction in E. coli, a 4.4-log reduction in L. brevis, and a 6.0-log reduction in S. cerevisiae. Total pulse energies of 200 and 250 kJ/L resulted in greater than 5-log reductions in microbial counts in stored PEF-treated milk, and the growth of surviving microorganisms was slow during storage for 15 d at 4℃. PEF treatment did not change milk physical properties such as pH, color, or particle-size distribution (p<0.05). These results indicate that a relatively low electric-field strength of 10 kV/cm can be used to pasteurize low-fat milk.

• Journal of Information Display
• /
• 제6권4호
• /
• pp.45-48
• /
• 2005

By applying a critical field treatment instead of the conventional surface treatments such as soft rubber roller, ion beam irradiation, adhesive taping, and laser irradiation, electron emission properties of screen-printed carbon nanotubes (CNTs) were enhanced and investigated based on the emission current-voltage characteristics through scanning electron microscopy. After nanotube emitters were activated at the applied electric-field of 2.5 V/um, the electron emission current density with good uniform emission sites reached the value of 2.13 mA/$cm^2$ , which is 400 times higher than that of the untreated sample, and the turn-on voltage decreased markedly from 700 to 460 V. In addition, enhancement of the alignment of CNTs to the vertical direction was observed.

• Journal of Electrical Engineering and Technology
• /
• 제5권3호
• /
• pp.484-492
• /
• 2010

Magnetic switch is a kind of saturable inductor, which utilizes nonlinearity of the magnetization curve of ferromagnetic materials. The right understanding of the saturation phenomena, magnetic properties, voltage-time product, and switching characteristics of the magnetic switch is essential in designing the magnetic pulse compressor (MPC). In this paper, the historical background of research on the MPC, fundamental physical properties of the magnetic switches, and application fields of the MPC are presented. Further, an in-depth analysis of pulse compression in series and parallel MPCs is incorporated. As practical application examples, a series MPC used for water treatments and a parallel MPC used for pulsed electric field (PEF) inactivation of bacteria are cited.