• Journal of environmental and Sanitary engineering
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• v.11 no.2
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• pp.65-73
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• 1996

The objective of this study is to investigate the removal efficiency of volitile organic compounds in soil, and the mechanism of desorption by bench scale microwave heating, Silt soil used for experiment and was impregnated with toluene, tetrachloroethylene, o-xylene and p-dichlorobenzene and the microwave treatment was conducted in a modified domestic microwave oven : 2450MHz, 700W. According to the results of the research the removal efficiency was improved with increasing water contents and the soil temperature appeared to plateau period extending to 2-3minutes corresponds to the temperature a which steam distillation was expected. The value of removal rate constant (k) were calculated on dry and moisty silt soil, respectively, which showed linear with increasing microwave heating time. Therefore, addition of a certain amount of water to the contaminated soil can efficiently enhance the ability of the soil to absorb microwave energy and promote the evaporation of the volitile contaminants.

• Journal of the Korean earth science society
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• v.38 no.2
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• pp.150-160
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• 2017

In order to determine the porosity of rock, the 'standard test method for porosity and density of rock' proposed by the Korean Society for Rock Mechanics is commonly used. However, the standard test method, which uses a drying oven, takes 8 to 24 hours to complete the test in taking samples out of the oven every four hours and measuring the weight of the specimen. To complement these disadvantages, we devised a method for measuring rock porosity by using a microwave oven. The devised method reduced the cause of errors and the inconvenience occurred in the process of weighing samples by constructing a weight monitoring system, which monitors the drying process. A suitable heating/pause time was set up to maintain the temperature of sample below $105{\pm}3^{\circ}C$ in drying process, and an alarm system was implemented in order to stop drying process when the weight change of the rock sample is within 0.1% of the initial weight. The porosity was determined from the dry weight of the sample, which was obtained by the curve fitting of weight monitoring data. Then, the porosities obtained by using the microwave oven were compared with those obtained by the standard test method. Test results using sandstone samples showed that the porosities obtained by a microwave oven was similar to those obtained by the standard method and the porosity difference between two methods was as large as 0.4%. In addition, repeated porosity measurement using the same specimen showed that the standard deviation of the porosity, which reflects the precision of the measurement was as good as 0.23%. Therefore, a microwave oven porosity measurement system can give the porosity of rock samples with high reliability.

• Korean journal of food and cookery science
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• v.8 no.4
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• pp.411-419
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• 1992

Retention of ascorbic acid in vegetables as influenced by various blanching methods was measured and the effects of blanching time, amount of water added, and with or without lid on the retention were compared. It was found that blanching with small amount of water and without lid generally retained the higher activity of ascorbic acid. Although steam blanching showed the highest retention of the vitamin, the longer heating time was needed to blanch the vegetables. Blanching by microwave oven has revealed that addition of small amount of water did not affect the retention. From the scoring difference test for texture of blanched spinach, the samples which were indicated as best in texture by the 8-panel members have retained 73~96% of ascorbic acid and samples blanched by microwave oven for 60 seconds showed highest retention.

• Journal of Nutrition and Health
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• v.22 no.3
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• pp.159-166
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• 1989

The effect of blanching time and power settings of microwave oven on the ascorbic acid retention in seven kinds of vegetables were investigated. The vegetable were blanched for 120 or 180 sec. at three different power setting, 650 watt(high power), 500 watt(medium power) and 160 watt(low power). The retentions of ascorbic acid in cabbage, garland chrysanthemum, mungbean sprout, amaranth and carrot were higher when they were blanched at the high power than those blanced at the lower power stettings. Blanching of spinach and yul-moo(small korean radish) showed that the vitamin was more retained by the medium power heating. Blanching at the low power revealed that the ascorbic acid retention was reduced remarkably as the blanching time increased. From the scoring difference tests the 10-panel members indicated that the texture of three-tested vegetables was more acceptable when they were blanched at the high power setting.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1741-1743
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• 1996

This paper presents simulations of the pancake in the simplified 3D microwave oven. The results were compared with experimental data. For the comparison we used infrared photography of the heated pancake and electric field distribution obtained by simulation. Finite Element Method (FEM) using edge element is employed for the simulation. For solving the large sparse system parallelled QMR method was used.

• Korean Journal of Food Science and Technology
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• v.47 no.1
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• pp.63-69
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• 2015

The aim of this study was to investigate the deformation of packaging materials used for ready-to-eat (RTE) foods after the retort process and microwave heating. From the multilayer films consisting of polyethylene terephthalate (PET), polyamide (PA), and cast polypropylene (CPP) in a stand-up pouch form used for RTE foods, some deformation of the CPP layer, which was in direct contact with the food, was observed after the retort process and microwave heating. The damage was more severely caused by microwave heating than by the retort process. This may be attributed to diverse factors including the non-uniform heating in a microwave oven, the sorption of oil into the packaging film, and the different characteristics of food components such as viscosity, salt and water content. The development of heat-resistant packaging materials and systems suitable for microwave heating of RTE foods is required for the safety of consumers.

• Journal of the Mineralogical Society of Korea
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• v.30 no.3
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• pp.103-112
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• 2017

In order to transform arsenopyrite into pyrrhotite and to decrease As content by less than 2,000 mg/kg, pulp sample and non-magnetic pulp sample were heated in a microwave oven at different heating times and were separated through wet-magnetic separation. As the microwave heating time increased, the phase of pyrrhotite was extended to become arsenopyrite entirely. The melting pores and micro-cracks occurred on the pyrrhotite due to hot spot phenomenon with microwave heating. The heated raw pulp sample (As content : 19,970.13 mg/kg) and non-magnetic pulp sample (As content : 19,970.13 mg/kg) which were heated in a microwave oven for 10 minutes were separated through wet-magnetic separation and magnetic fraction containing less than 2,000 mg/kg of As content was recovered only from the heated sample of magnetic separation. It was discovered that for the sulfide complex ore with As penalty imposed on, if microwave heating and wet-magnetic separation are effectively utilized, magnetic fraction. We expect to be able to obtain ore minerals with an arsenic content below the penalty charge.

• Food Science of Animal Resources
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• v.38 no.3
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• pp.433-441
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• 2018

The objective of present study was to investigate the effect of cooking and their combinations with re-heating methods on the formation of cholesterol oxidation products (COPs) in stored chicken thigh meat. Pan roasting, steaming, oven grilling, charcoal grilling, and microwaving were used for cooking. Re-heating of samples was done using the same cooking methods or microwaving after 3 and 6 d of refrigerated storage. Cooking and re-heating resulted in reduction of crude fat and cholesterol contents of chicken thigh meat depending on storage period before re-heating. Cooking and storage period had no influence on the total amount of COPs. The highest total amount of COPs was observed in meat samples cooked by steaming and reheated by microwaving after 6 d of storage, which showed similar value to raw chicken meat stored for 6 days. However, different re-heating methods formed different types of COPs depending on storage period before re-heating. The high amount (p<0.05) of 25-hydroxycholesterol or ${\alpha}-epoxide$ was detected in meat samples reheated by steaming or microwaving at 3 or 6 d of storage after steamed cooking, respectively. As a result, the combination of steaming and re-heating with microwaving could increase the total amount of COPs in chicken thigh meat and different cooking/re-heating methods could form different types of COPs, even though no significant difference in the total amount of COPs depending on storage period.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.5
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• pp.674-680
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• 2005

The purposes of this study were to compare the effect of several reheating treatments (heating in the frying pan, convection oven and microwave oven) on sensory characteristics and to evaluate the safety during storage period of cook/chill Pajeon. The sensory evaluations were made on 5 sensory attributes by a 9-member panel using quantitative descriptive analysis (QDA). The fresh cooked Pajeon and the Pajeon reheated in the frying pan obtained a significantly (p<0.01) higher score in taste than the ones reheated in a convection oven and microwave oven. The reheated cook/chill Pajeon had a significantly (p<0.01) lower score in flavor than the freshed cooked one. Regardless of the reheating methods, sensory scores in texture of the Pajeon reheated at $v$ for 1 day were not different from that of fresh cooked one. However, the scores of the reheated ones in a convection oven and in a microwave oven decreased with storage time up to 5 days at $3^{\circ}C$. On the other hand, the Pajeon reheated in the frying pan, even after 3 days' storage at $3^{\circ}C$, was not found to be inferior to the freshed cook one in every quality attributes except flavor. Therefore, the reheating treatment in frying pan may be superior to those in a convection oven and a microwave oven. The safety of Pajeon was also evaluated by measuring total count, coliform count, psychrotrophic count, acid value and peroxide value during 5 days of storage periods at $4^{\circ}C$. Total counts of Pajeon was ranged from not detectable to $5.2\times10^2$ CFU/g. The coliform and psychrotroph were not detected at all experiments. The acid values were ranged from 1.90 to 4.03 mg of KOH/g of fat until 5 days at $4^{\circ}C$. And the peroxide values were ranged from 3.63 to 12.50 meq of peroxide/kg of fat until 5 days of storage period. Therefore, these results demonstrated that Pajeon is microbiologically and chemically safe during 5 days of storage period at refligeration temperature.

• Korean Journal of Food Science and Technology
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• v.26 no.6
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• pp.696-703
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• 1994

The purpose of this study was to investigate the gelatinization properties of potato starch heated with microwave. Two types of potato starches were prepared; In group A raw potato starch was heated with microwave and in group B potato starch was isolated from potato heated with microwave. Both groups were exposed to the microwave energy in a 560W, 2,450 MHz oven for 60, 120, 180 and 300 seconds. Gelatinization behaviour by DSC made a few differences according to the ratio of starch to water. As the microwave heating time took longer, gelatinization temperature and gelatinization $enthalpy({\bigtriangleup}H_1)$ were decreased in and melting $enthalpy({\bigtriangleup}H_2)$ was increased in group A. Whereas they were increased in group B. In both groups, maximum viscosity in gelatinization by Brabender amylogram was decreased by microwave heating. Then the peak of the maximum viscosity was shifted to higher temperature and cold viscosity was slightly increased. In group A, viscosity in gelatinization and light transmittance by NaOH was increased in initial stage and gel volume in gelatinization by KSCN was decreased. On the other hand, in group B, viscosity by alkali was slightly decreased, but light transmittance by NaOH was almost never changed. Gel volume is decreased like group A.