• Applied Biological Chemistry
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• v.41 no.6
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• pp.431-436
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• 1998

The optimum ohmic heating condition of apple juice was investigated with model solution. The temperature rise of model solution was found to be $7.8,\;21.0,\;47.4^{\circ}C/min$ when the distances between electrodes were 29, 22, and 17mm, respectively. The heating rate increased proportionally with the numbers of electrode pairs, 1 to 3 and highly dependent on applied voltage. The heating rate was not affected by the frequencies ranged from 60 Hz to 60 KHz and the wave form of applied alternating electric current. The apple juices prepared by ohmic heating sterilization revealed similar physicochemical properties to that by commercial sterilization.

• Bulletin of Food Technology
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• v.22 no.4
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• pp.808-815
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• 2009

Joule heating은 내부 가열법 중의 하나이며, Ohm의 법칙에 따라서 식품에 직접전기를 통전하여 식품이 갖고 있는 전기저항성에 의해서 식품자체를 자기 발열시키는 가열방법이다. 따라서 Joule 가열을 Ohmic heating 또는 통전가열이라고도 부르고 있다. 열전달성이 느린 고형물 또는 고점도의 Paste형 식품도 어느 정도 전도성이 있으면 신속하면서도 균일하게 열처리를 할 수 있다. 최근 일본에서는 통전가열에 대한 연구가 활발히 진행 중에 있으며, Joule 가열 연구 및 산업화 동향의 일부를 소개하고자 한다.

• Journal of the Korean Vacuum Society
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• v.2 no.3
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• pp.288-293
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• 1993

통전가열, 접촉냉각, 전기적 bias 및 시료 교환을 자유로이 할 수 있는 다기능의 새롭고 간단한 시료 고정장치를 저온 및 초고진공 상태에서 기체와 여러 방향의 시료표면 사이의 상호작용을 연구하기 위하여 고안하였다. 이 장치로써 2분 이내에 기판의 온도를 1600K에서 20K로 2분 이내에 냉각시킬 수 있었다. 그러므로 청결한 표면위에 수소나 He이나 Ne을 제외하고는 대부분의 기체를 흡착시킬 수 있게 되었다. 이러한 장치는 표면에서의 상변화, 기체와 표면의 화학반응의 연구에 중요하게 활용될 수 있다.

• Journal of the Korean Vacuum Society
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• v.3 no.4
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• pp.377-381
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• 1994

초고진공(UHV) Scanning Tummeling Microscopy(STM)을 제작하였다. 8인치 프란지에 부착한 STM은 초고진공에서 시료의 통전가열이 가능하며 다른 표면 측정방법의 적용과시료처리가 용이하다. 외부로부터 초고진공을 깨지 않고 시료와 tip의 도입이 가능하며 tip을 가열할 수 있다. 완성된 장치로 Si(111)-7$\times$7 구조의 STM상을 얻었다.

• Journal of Korea Ship Safrty Technology Authority
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• s.37
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• pp.2-11
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• 2014

본 연구에서는 최근, 전기자동차 및 소형 레저용 선박을 중심으로 연구가 진행 중인, 대용량 이차전지의 용량 증대를 위하여 필요한 내부 전극 접합 기술에 관하여 연구하였다. 종래의 초음파 용접으로 적층할 수 있는 적층량의 한계를 극복하기 위한 방안으로 전극 소재에 직접 가열을 통한 용접 방법이 아닌 용가제 금속을 적용하여 전극을 접합시켜, 통전성과 인장강도를 증대시킴과 동시에 열적요인으로 인한 전극표면에 화학적 활성물질의 변성을 최소화할 수 있는 저온 접합 방법에 대하여 연구하였다. 부연하여 용접을 위하여 무리하게 출력을 상승시킬 경우 용접열의 영향으로 전극의 변형 및 활성물질의 변성을 야기함과 동시에 최종 페키징 이후 출력저하, 발열 등, 배터리의 안정성을 저하시키는 요인으로 작용한다. 따라서 본 연구에서는 고주파 유도가열을 통한 유도 가열 방식의 접합 방법과 용융 도금을 통한 용가제 금속의 전처리를 통한 종래와는 차별화된 전극접합 방법을 소개한다.

• Korean Journal of Materials Research
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• v.9 no.11
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• pp.1112-1116
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• 1999

Thermoelectric effects on the temperature changes at the solid- and liquid-phase and its interface were studied by using the unidirectional solidification of $\textrm{Bi}_{2}\textrm{Te}_{3}$. Cooling or heating effects measured with current density. polarity and current passing time were quite different. By separating sole Peltier, Thomson and Joule heat theoretically and experimentally, the Peltier coefficient at the solid/liquid interface of $\textrm{Bi}_{2}\textrm{Te}_{3}$ was -1.10$\times\textrm{10}^{-1}$V, and the Thomson coefficients of solid- and liquid-phase were 7.31\times\textrm{10}^{-4}V/K, 5.77\times\textrm{10}^{-5}V/K, respectively. When D.C. passed from solid-phase to liquid-phase during the crystal growth of $\textrm{Bi}_{2}\textrm{Te}_{3}$ the crystal with more directionality was obtained owing to increase of the temperature gradient in liquid by the Peltier cooling. But in reverse current direction, the crystallinity was not changed significantly.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.10
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• pp.1367-1375
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• 2010

In this study, optimization of the process parameters of the resistance spot welding of a sheet of aluminum-coated boron alloyed steel, 22MnB5, used in hot stamping has been performed by a Taguchi method to increase the strength of the weld joint. The process parameters selected were current, electrode force, and weld time. The heating temperature and heating time of 22MnB5 are considered to be noise factors. It was known that the variation in the thickness of the intermetallic compound layer between the aluminum-coated layer and the substrate, which influences on the formation of nugget, was generated due to the difference of diffusion reaction according to heating conditions. From the results of spot weld experiment, the optimum weld condition was determined to be when the current, electrode force, and weld time were 8kA, 4kN, and 18 cycles, respectively. The result of a test performed to verify the optimized weld condition showed that the tensile strength of the weld joint was over 32kN, which is considerably higher than the required strength, i.e., 23kN.

• Particle and aerosol research
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• v.5 no.4
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• pp.153-158
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• 2009

Tungsten carbide powder was fabricated with carbothermal reaction by pulsed electric current flowing in compact of tunsten oxide and carbon. The mixed powder of tunsten oxide and carbon was ball-milled into ultrafine powders. The mixed powder of tungsten oxide and carbon was put into carbon mold and heat-treated at $1050{\sim}1200^{\circ}C$ by pulsed electric current flowing. The formation of tungsten carbide powder could be achieved by heat treatment at $1200^{\circ}C$ for 10 minitues.

• Journal of the East Asian Society of Dietary Life
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• v.24 no.1
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• pp.80-91
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• 2014

The aim of this study was to establish the superiority of ohmic heating over conventional heating for the sterilization of mulberry juice. Heat treatment of fresh juice significantly reduced the concentration of soluble solids, lowered the pH, and lowered the reducing sugar content (p<0.01). Color measurements showed decreases in the L and a values and increases in the b, H and C values after heat treatment, although the total color differences were smaller after ohmic heating than after conventional heating of fresh juice. The antioxidant capacities, such as reducing power, FRAP, and DPPH, decreased in the order of fresh juice, ohmically heated juice and conventionally heated juice. Furthermore, the anthocyanin, flovonoid, and total antioxidant capacities of the juices significantly decreased in the same order. Sensory evaluations showed no difference between fresh and ohmically heated mulberry fruit juice excluding off-flavor, whereas conventionally heated juice received significantly lower evaluations. The microbial counts were zero in the juice after either heat treatment. Thus, ohmic heat treatment can be effectively used to sterilize fresh mulberry juice to obtain good shelf life with minimal physicochemical, color, antioxidant and sensory deterioration.

• Food Science and Preservation
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• v.6 no.4
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• pp.521-529
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• 1999

The high influx of imported fruits into Korea is threatening to price and quality competition of domestic fruits. This investigation was conducted to raise price and quality competition of domestic fruits and to develop new products. The scale of production and processing, amount of processing and new processing technology were discussed. The area of cultivation land as well as the rate of processing is decreasing annually, an item of processing is limited to several kinds. Accordingly in this study, the status of production and manufacturing of some fruits and the new processing technologies such as high voltage pulsed electric fields, high hydrostatic pressure, ohmic heating, membrane separation and microwave treatment have investigated to fruit processing. Consequently, the minimal processing technology has to take advantage of various agricultural products in the food industry.