• Journal of Advanced Marine Engineering and Technology
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• v.29 no.7
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• pp.744-749
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• 2005

This paper describes the performance improvement of power control system of magnetron (MGT) for microwave oven. The MGT is used extensively in household microwave oven and industrial microwave heating devices, and is operated by 3.0[kV] $\∼$5.0[kV] dc high voltage. The proposed power supply is consisted of a bridge rectifier, step-up converter(SUC) and its controller, half bridge inverter(HBI) and its controller, and full wave double voltage rectifier(DVR). In the proposed system, a good power factor can be obtained by the SUC' switching method that the inductor current waveforms follows that of the rectified voltage, and a line input power can be controlled to a range of 17.5[$\%$] by duty ratio (DR) adjustment of the HBI.

• Journal of Welding and Joining
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• v.15 no.6
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• pp.105-115
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• 1997

A numerical study is performed to predict the thermal response of a detailed card assembly during infrared reflow soldering. The card assembly is exposed to discontinuous infrared panel heater temperature distributions and high radiative/convective heating and cooling rates at the inlet and exit of the oven. The convective, radiative and conduction heat transfer within the reflow oven as well as within the card assembly are simulated and the predictions illustrate the detailed thermal responses. The predictions show that mixed convection plays an important role with relatively high frequency effects attributed to buoyancy forces, however the thermal response of the card assembly is dominated by radiation. The predictions of the detailed card assembly thermal response can be used to select the oven operating conditions to ensure proper solder melting and minimization of thermally induced card assembly tresses and warpage.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.08a
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• pp.249-257
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• 2004

Drying and curing characteristics of PCM resins using the induction heater and short-wave infrared emitter module was studied to develop a compact oven system for the high speed CCL and post-treatment equipment. Drying of the polyester resins using the induction heater and infrared heater showed that the blistering tendency of polyester resin coating increased regardless of additives and colors of resins as the heating rate and/or dry film thickness increased. The blistering of polyester resin coating layer occurred when the heating speed was over than $25^{\circ}C/sec$ for the dry film thickness of $19\~20um$, which is the typical thickness of finish coating in CCL. So did it when the heating speed was over than $40^{\circ}C/sec$ for the dry film thickness over than 10 um. The heating efficiency of paint coated steels by the infrared heating was strongly dependent on the colors of paint coating and generally increased for the dark surface and/or coating. But the faster drying of the PCM resin coatings increased the blistering tendency of coating layer. The blistering limit for the typical finish coating by the infrared heating was estimated as the heating rate slower than $20^{\circ}C/sec$ regardless of colors of PCM resins.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.5
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• pp.67-74
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• 2020

To predict the thermal deformation of an oven cabinet during the enamel process, we propose a simple finite element analysis method comprising two steps: heating and cooling. To this end, the basic mechanical and thermal properties such as thermal expansion of the enamel and steel plate were experimentally studied, and the mechanical properties of four different stainless steel (SUS) plates were evaluated to select the target material for the oven at high temperature conditions from 400 ℃ to 700 ℃. In the first analysis step of the enamel process, the SUS plate was heated to 850 ℃ and was then thermally expanded without considering the enamel coating. Next, assuming the perfect bonding of two materials (enamel coating and metal plate), the enamel plate was allowed to cool to room temperature till 22 ℃. From the results of comparing the experimental and analytical data, we can make a conclusion that the proposed method can be applied to evaluate the thermal deformation of enamel products. Especially, the thermal deformation of the oven can be predicted with different enamel coating conditions, such as uniform and nonuniform coating thickness.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.3
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• pp.489-494
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• 1998

For the purpose of improving the qualities of popcorn, potato, frozen hotdog and steamed egg, the effects of food height(0mm: HO, 5mm: H5, 10mm, 15mm: H15) for microwave cooking on physicochemical properties were investigated. In popcorn, weight loss was decreased as height increased while volume of popcorn was increased, which indicated that popcorn was poped very well as height increased. H10 showed the highest taste score in sensory evaluation. In potato, degree of gelatinization was increased as hight increased. H10 showed the highest overall acceptance score. In frozen hotdog, hardness of hotdog was decreased as hight increased and H15 showed the lowest hardness score (408.8g). In steamed egg, H5 showed the highest temperature and H10 showed the highest overall acceptance score. Physicochemical properties of food were changed by heating height of microwave heating.

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.2
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• pp.122-132
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• 2009

Adsorption of toluene by activated carbon fiber (ACF) coated with dielectric heating element and desorption by applying microwave were investigated. In order to prepare adsorbent so that VOC can be desorbed by microwave heating, fine dielectric heating element with nano size was coated on the surface of the ACF using hybrid binder. Eight adsorbents (ACF-DHE, Activated Carbon Fiber coated with Dielectric Heating Element) were prepared with different amount of dielectric heating element, kinds of hybrid binder, and solvent. In order to investigate adsorption characteristics, BET surface area, pore volume, and average pore size were measured for each adsorbent including ACF. Breakthrough experiments with toluene concentration, flow rate, bed length using fixed bed reactor were performed to investigate adsorbality of adsorbent, and results were compared with that of the ACF. Desorption reactor was constructed with modified microwave oven to investigate heating effect on ACF-DHE by applying microwave power. Each adsorbent saturated with toluene were put into desorption reactor. Composition of desorbed gas generated by applying controlled microwave power to reactor was measured. Up to now, hot air desorption method has been used. Experimental results showed that desorption method with new adsorbent prepared by coating dielectric heating element on ACF can be used for industrial application.

• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1583-1588
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• 1999

Garlic pieces without peeling were subjected to hot air heating at $60{\sim}90^{\circ}C$ for 30 min. and microwave oven heating for 10 sec to reduce the strength of garlic flavor. Volatile compounds of the treated garlic were decreased, as the heating temperature was raised. Garlic heated at 70, 80 and $90^{\circ}C$ had 20%, 31% and 49% less volatile compounds, respectively, compared to those of the control. Microwave oven heating revealed a similar trend to those heated at $60{\sim}80^{\circ}C$. As the heating temperature was raised, glucose, fructose and fructooligosaccharide contents in the heated garlic were decreased. Pyruvic acid contents in garlic, a degradation product of alliin, was decreased as the heating temperature was raised, but contents of the other organic acids were not affected. Arginine, the main amino acid in garlic was decreased by the hot air heating, but was not affected by the microwave heating. Glutamic acid and tyrosine contents were decreased in all the treated garlic samples.

• Food Science and Preservation
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• v.4 no.2
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• pp.173-180
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• 1997

The effects of sugars and heating methods on the sugar infilteration, hardness, color and organoleptic characteristics were investigated for quality improvement of sugared chestnuts. Among the tested sugars, isomaltooligosugar was the most effective on the rate of sugar infilteration. High temperature increased the rate of sugar infilteration during sugaring process, but color and flavor were deteriorated at 9$0^{\circ}C$. The most suitable temperature for sugaring process was 7$0^{\circ}C$. The product sugared with fructooligosugar recoreded the highest score in hardness, odor and preference than any other sugars tested and increased the rate of sugar infilteration when mixed with sugar at same amount. The changes of soluble solids in chestnuts boiled with microwave oven were ranged from 18。Brix to 32。Brix, while chestnuts heated in general were from 18。Brix to 28。Brix. Chestnuts boiled with microwave heating were sugared rapidly. The hardness of boiled and sugared chestnuts was lower when treated with microwave than with general heating. Hunter's L and b value of sugared chestnut treated with microwave decreased during processing but a value somewhat increased.

• Journal of the Korean Society of Industry Convergence
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• v.3 no.4
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• pp.345-351
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• 2000

The change of crystalline structure of drawn PP filaments were investigated. Samples were treated by isothermally annealed after elevated heating from $20^{\circ}C$. Measurements were carried out with XRD for crystallite size and density gradient tube for crystallinity. Isothermally heat treatment were carried out at the temperature of $100^{\circ}C$, $120^{\circ}C$ and $140^{\circ}C$ for 10min., 30min. and 60min. in dry oven. The isothermal heat treatment after elevated heating from $20^{\circ}C$ were carried out at the temperature of $100^{\circ}C$, $120^{\circ}C$ and $140^{\circ}C$ for 10min., 30min. and 60min. with heating rate of $1^{\circ}C$/min., $5^{\circ}C$/min. and $10^{\circ}C$/min. From the results of this study, it found the following facts. It was found that the crystallinity and crystallite size of (110) plane of sample were increased with increasing of annealed temperature and time. Also crystallinity and crystallite size of samples which were isothermally annealed after elevated heating from $20^{\circ}C$ were higher than those of isohtermally annealed samples.

• Journal of Conservation Science
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• v.19
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• pp.31-42
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• 2006

There are many materials used in restoring missing parts of pottery and ceramics and they are used according to the each quality of materials. In our research we tried to find the new repair materials to solve many problems exposed in the existing repair materials. As a result, we made new repair materials that we properly put oven bake clays into repair epoxy putty which is being used as oven bake clays for a long time. Fortunately, through testing yellowing, vickers hardness, coloring and heating temperature, We could get an idea that new repair materials would be the best materials in the efficiency of restoration, yellowing, and coloring.