• The Korean Journal of Food And Nutrition
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• v.22 no.3
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• pp.387-395
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• 2009

This study was conducted to investigate the effects of starch concentrations and heating conditions on the gel characteristics of arrowroot starch. Arrowroot starch gels with various pHs, and starch concentrations, were prepared using different temperatures and heating times, and then stored for 24 hrs at $4^{\circ}C$. The hardness of sample gels made at pH 2.0 and 4.0 increased as the starch concentration increased from 7% to 10%, with the maximum value of 94 N being obtained when the gel was prepared at pH 4.0 with a starch concentration of 10%. The maximum hardness of samples prepared with concentrations of starch ranging from 7~9% appeared at $80^{\circ}C$, regardless of the heating temperature and time. Furthermore, the hardness of samples prepared at greater than $100^{\circ}C$ was relatively lower than that of samples prepared at other temperatures. When a starch concentration of 8% was used, the degree of gelatinization(DR) increased as the heating temperature increased, with the maximum value of DR being about 76% at $120^{\circ}C$, regardless of heating time. After storage for 24 hrs, the hardness of samples prepared at $70^{\circ}C$, $80^{\circ}C$ and $90^{\circ}C$ appeared to decrease, while that of samples prepared at $100^{\circ}C$, $110^{\circ}C$ and $120^{\circ}C$ increased. The correlation between hardness and the degree of gelatinization or retrogradation was very high when samples were prepared at $80^{\circ}C$ with a starch concentration of 9%, as indicated by a correlation coefficient of greater than 0.95. Overall, the microstructures of freeze-dried arrowroot starch gel were composed of a continuous network of amylose and amylopectin with fragmented ghost structures in an excluded phase, but these ghost structures were more evident after storage and with increased heating temperature.

• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.1
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• pp.10-17
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• 2001

In this paper are presented main power and gasdynamic characteristics of hypersonic test cell of Research Test Center (RTC) of Central Institute of Aviation Motors (CIAM). The distributions of temperature and Mach number at the exit of the aerodynamic nozzle of test cell are received at simulation conditions of flight at Mf=6. Values of available pressure difference and throttling characteristics for various operational modes of test cell, including the loading of working section by Scramjet model without the heating of air at entrance to the aerodynamic nozzle and with the heating of air, are received too.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.164-165
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• 2017

본 논문은 직렬 공진형 컨버터를 이용하여 낮은 저항을 갖는 주방 용기를 가열하기 위한 유도 가열(Induction Heating; IH)용 공진형 컨버터와 코일 설계방법을 제안한다. 기존 IH 시스템은 저항이 작은 용기를 가열할 때 낮은 전압이득으로 인해 정격보다 큰 전류가 흘러 스위칭 손실 및 전도 손실이 증가하고 소자의 정격 전류량을 초과하는 문제가 발생한다. 본 논문에서는 용기에 따른 임피던스를 분석하고 다양한 저항 조건의 용기를 모두 가열하기 위한 적절한 IH용 코일 설계 방법을 제안한다. 이는 2.4 kW의 최대 전력을 가지는 IH용 공진형 컨버터 시작품을 사용하여 제안하는 설계의 타당성을 검증하고자한다.

• 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.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.7
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• pp.881-885
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• 2006

The product formation and changes in color of glucose/glutamine model system were investigated in relation to heating temperature and time. The mixtures of glucose and glutamine in equal molar ratio were heated at 125, 150 and $175^{\circ}C$ for 10, 20 and 30 minute, respectively. Acetic acid, butanoic acid, 2-butenoic acid, di-(2-cthylhexyl)phthalate, 2,3-dihydro-3,5-dihydroxy-6-methly-4H-pyran-4-one and 5-hydroxymethylfurfural were identified as a major compounds, and 1,3-dimethylbenzene, 2-ethylhexanol, furfural, 5-methylfurfural, 2-pyrrolidinone, and 2,6-di(t-butyl)-4-hydroxy-4-methyl-2.5-cyclohexadien-1-one as 6 minor compounds by using GC/MS. The contents of acetic acid, 2-ehylhexanol and 2-pyrrolidinone increased with increased heating temperature and time, whereas the formation of the other 9 compounds increased up th heating conditions of $150^{\circ}C$ for 10 or 20 min or $175^{\circ}C$ for 10 min, and decreased dramatically with heating above those conditions. Color parameter $L^*$ decreased with increasing heating conition, resulting in dark brown color in final products. Changes of redness parameter $a^*$ and yellowness $b^*$ showed similar to those of the contents of 9 compounds mentioned as above.

• Korean Journal of Food Science and Technology
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• v.26 no.4
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• pp.365-369
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• 1994

In attempt to explain the effect of heat processing on the product quality in manufacturing strawberry jam, the heat stability of anthocyanin in strawberry by addition of some sweetners was studied, and the effect of sucrose by concentration and pH were also investigated. The heat stability of anthocyanin was maximum at pH 2.5 when maintaining at $87^{\circ}C$ for 60 minutes initially, but it was shifted to pH 3.0 after additional heating of 120 minutes. When the corn syrup, sucrose and glucose were used as a sweetner for manufacturing strawberry jam, the results showed that heat stability of anthocyanin in corn syrup was higher than that in sucrose and fructose, and the optimum concentration of sucrose for heat stability was 66 Brix%. The results also showed that anthocyanin content in strawberry jam significantly decreased logarithmically at $37^{\circ}C$, and spreadmeter value changed slightly at $37^{\circ}C$storage but it was not significant.

• 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.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.8
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• pp.1193-1199
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• 2003

As a result of resistant starch yield depending on heating temperature, moisture content, storage temperature and heating-cooling cycle with RSM (response surface methodology), high amylose corn starch (46%) was appeared higher than normal corn starch in the yield (22%). At the high amylose corn starch, optimum conditions for resistant starch formation were 6 times of heating-cooling cycle, 108$^{\circ}C$ heating temperature and 67% moisture content at the 2$0^{\circ}C$ storage temperature, which resulted in 25% yield with these experiment conditions. Affecting factor for the resistant starch formation was arranged according to heating -cooling cycle, moisture content, heating temperature and storage temperature. Raw corn starch granule was destructive and appeared a porous reticular structure by the resistant starch formation. Color became dark and increased yellowness by caramelization during heating processing. Heating-cooling processing was the result of decreased hardness, cohesiveness, springiness and gumminess.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.1
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• pp.1-5
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• 2003

This study was carried out to prepare the depolymerized alginates by physical treatment processing with organic acids. The applied physical treatment methods were autoclaving, microwaving, and ultrasonicating, Among several physical depolymerization methods, autoclaving treatment was the most effective for hydrolyzing the alginate to low molecular compounds such as oligosaccharides. Citrate was most effective catalyst in hydrolyzing alginate to some oligosaccharides among organic acids. An acceptable autoclaving conditions for hydrolyzing alginate to oligosaccharides were to treat at $110^{\circ}C$ for 90 min and $120^{\circ}C$ for 60 min, respectively. The maximum depolymerization percentage produced by autoclaving was $56.8\%$. The depolymerized alginates prepared by autoclaving at $110^{\circ}C\;and\;120^{\circ}C$ has oligosaccharides of $3\~4 $and $7\~8$ species, respectively. The optimum condition for alginate oligosaccarides was autoclaving treatment with $0.5\%$ citrate solution at $120^{\circ}C$ for 90 min.

• Current Research on Agriculture and Life Sciences
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• v.28
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• pp.53-62
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• 2010

The effect of far-infrared (FIR) irradiation on the functional compounds of grape seeds extract were evaluated. Grape seed was dried on different heating power (0, 900, 1800 W) and heating time (0, 20, 40 min) with far-infrared drier. Contents of soluble solids, catechins, total phenolics and total flavonoids along with Hunter's color value, electron donating ability (EDA) and nitrite scavenging activity were analyzed. The soluble solids, Hunter's L value and a value were not significantly different from control samples. Cathechin, procyanidin $B_2$ and epicatechin contents changed with heating time. In the treated sample, total cathechins content was found maximum at 900 W of heating power and 20 min of heating time with a high level of total phenolics, total flavonids and EDA. These results indicated that FIR irradiation of grape seed could enhance antioxidant activities of its extracts by increasing the amounts of functional compounds. Moreover, response surface methodology(RSM) was applied to predict optimum conditions for heating by FIR rays of grape seeds. Based on superimposition of contour map with respect to total phenolics, total catechin and EDA, optimum ranges of heating conditions were heating power of 621.82~818.18 W and heating time of 16.3~19.83 min.