• Korean Journal of Food Science and Technology
• /
• v.23 no.3
• /
• pp.355-359
• /
• 1991

Effects of temperature and pH on thermal degradation of monosodium glutamate(MSG) were investigated during heating of 2% MSG solution at $100{\sim}200^{\circ}C\;and\;pH\;4{\sim}9$. The results showed that the degradation of MSG was very significantly affected by heating temperature and pH. Three hours of heating at $pH\;4\;and\;120^{\circ}C$ resulted appr. 73% MSG degradation while 3 hours at $100^{\circ}C$ decreased only 12%. The comparison study of initial rate of MSG degradation and degradation rate constants showed the highest degradation rate and rate constant and low values in the range of $pH\;6{\sim}8{\sim}$. The values of activation energy calculated from linear relationship of rate constants and 1/T were 18.3 and 9.2 kcal/mole for pH 4 and 5, respectively.

• Transactions on Electrical and Electronic Materials
• /
• v.5 no.3
• /
• pp.120-121
• /
• 2004

YBaCuO thick films were fabricated by plasma enhanced chemical vapor deposition, and the crystallinity and the superconducting properties were investigated. The growth temperature to obtain the thick films was decreased by around 150$^{\circ}C$ due to plasma enhancement. The zero resistivity temperatures for films grown at 590$^{\circ}C$ and 620$^{\circ}C$ were 55 and 80 K, respectively.

• Korean Journal of Food Science and Technology
• /
• v.38 no.3
• /
• pp.355-360
• /
• 2006

Antioxidative activity and physicochemical characteristics of heat-treated licorice extracted by ethyl-acetate (EtOAc) and ethyl-alcohol (EtOH) were evaluated at various treatment temperatures (110, 120, 130, 140, and $150^{\circ}C$), times (1, 2, 3, 4, and 5 hr), and moisture contents (10, 20, 30, 40, and 50%). Maximum extraction yields of EtOAc treated at $140^{\circ}C$, 2 hr, and 20% moisture content and EtOH extracts treated at $120^{\circ}C$, 2 hr, and 40% moisture content were 9.48 and 32.90%, whereas those of control were 3.74 and 14.60%, respectively. Highest total polyphenol content was obtained from 13.95 mg/g EtOH extract treated at $150^{\circ}C$, 3 hr, and 30% moisture content (control: 6.92 mg/g). Highest antioxidative activity $(IC_{50})$ was obtained from 0.32 g/L EtOAc treated at $140^{\circ}C$, 2 hr, and 20% moisture content (control: 0.57 g/L). Highest ascorbic acid equivalent antioxidant activity value of 2,112.61 mg ascorbic acid (AA) eq was obtained from EtOAc extract treated at $120^{\circ}C$, 2 hr, and 40% moisture content (control: 1,920.27 mg AA eq). Optimum heat treatment conditions were $130-140^{\circ}C$, 3 hr, and 30% moisture content.

• Korean Journal of Food Science and Technology
• /
• v.32 no.3
• /
• pp.654-658
• /
• 2000

Flavor components focused on the methyl pyrazines(2,3-dimethyl pyrazine, 2,3,5-trimethyl pyrazine, tetramethyl pyrazine) of microwave-roasted cocoa beans were determined and compared with those of conventionally-roasted cocoa beans. Domestic microwave oven was modified to design the microwave roasting system. Temperature measurement technique using thermocouple probes was developed to determine the center temperature of cocoa beans during microwave roasting. Microwave roasting was carried out under two different conditions. Under the first condition, roasting time was fixed to 30 min, while roasting temperature was varied to $110^{\circ}C,\;120^{\circ}C,\;130^{\circ}C,\;140^{\circ}C,\;and\;150^{\circ}C$ Under the second condition, roasting temperature was fixed to $130^{\circ}C$, while roasting time was varied to 5 min, 10 min, 20 min, and 30 min. Conventional roasting was done at $120^{\circ}C$ for 15 min as a reference. Amount of methyl pyrazines and their ratios were influenced by microwave roasting temperature and roasting time. The most suitable methyl pyrazine ratio of cocoa beans was obtained at $140^{\circ}C$ for 30 min of microwave roasting.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.11a
• /
• pp.252-255
• /
• 1999

The effect of calcination temperature(1st and 2nd calcining at 110$0^{\circ}C$ , 120$0^{\circ}C$ and 130$0^{\circ}C$ respectively) on physical properties of BMNT Ceramics ware investigated. The optimum 1st and 2nd calcination temperature were 120$0^{\circ}C$ , and sintering temperature was 155$0^{\circ}C$. In this condition, the sintering density was 7.53 [g/㎤] and the dielectric constant, Q.f$_{0}$ and $\tau$$_{r}$ were 26, 80, 300[GHz] and +1.5[ppm/$^{\circ}C$] respectively in the microwave range.e.e.

• Korean Journal of Plant Resources
• /
• v.19 no.1
• /
• pp.139-143
• /
• 2006

To increase the contents of functional ginsenosides by conversion, especially ginsenoside-$Rg_3$ and $Rh_2$, the extracts of red ginseng were treated with high temperature and citric acid or apricot extract. When the extracts were subject to $120^{\circ}C$ for 2 hours, the content of ginsenoside-$Rg_3$ was increased 2 times than in control. When the extracts were subject to $120^{\circ}C$ and acidic conditions adjusted with citric acid, the ginsenoside-$Rg_3$, was detected 2.8 times, but other ginsenoside were decreased heavily to 65%. When the extract were treated with for 12 hours at $80^{\circ}C$, the content of ginsenoside-$Rg_3$ was increased to 3.3 times, Also, when the red ginseng extracts were treated with apricot extract, the ginsenoside-$Rg_3$ was detected to 4 times than in control, but other ginsenoside were decreased lightly to 35%, not same as at the $120^{\circ}C$ treatment.

• Polymer(Korea)
• /
• v.36 no.1
• /
• pp.93-97
• /
• 2012

Heat treatment effect of polyethylene (PE) separators was investigated after storage at 80, 100 and $120^{\circ}C$ for 1 h. All the samples showed enhanced tensile strength and modulus after heat treatment, but thermal shrinkage up to 15% was observed in PE films having newly formed dimple structure on the surface of fiber after annealed at 100 and $120^{\circ}C$. Although there was 5% of thermal shrinkage after annealing at $80^{\circ}C$, no such serious changes in PE fiber was observed. Furthermore, the separator was found to have enhanced cell performance with 1.3 and 2.3 times higher tensile strength and modulus after heat treatment at $80^{\circ}C$ for 1 h.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.36 no.1
• /
• pp.6-10
• /
• 2003

The optimum organic acid and temperature conditions were investigated for the preparation of oligosaccharides from agar. The tested organic acids were acetate, citrate, lactate, malate, and succinate and the conditions for oligosaccharides preparation were $0.3\%,\;0.5%;and\;0.7\%$ organic acid concentrations at $80\~120^{\circ}C.$ The low concentration of organic acid below $0.3\%$ decreased the degrading ratio and the high concentration up $0.5\%$ could not changed the degrading ratio. Conditions below $100^{\circ}C$ was not good for degrading agar. But $100^{\circ}C\;or\;120^{\circ}C$ was optimal temperature conditions for agarooligosaccharides according to the organic acid type and concentration. The organic acid concentration was $0.5\%$ and organic acid was the citrate or malate. The treatment time considered optimum was 120$\~$180 min. The maximal degrading ratio giving optimum conditions such as $100^{\circ}C\;and\;120^{\circ}C\;was\;35.5\%\;and\;38.7\%,$ respectively. The agarooligosaccharides prepared by autoclaving at $100^{\circ}C\;and\;120^{\circ}C$ were 2$\~$7 species oligomer.

• Korean Journal of Materials Research
• /
• v.5 no.3
• /
• pp.268-274
• /
• 1995

세라믹재료의 동탄성계수 측정을 위한 공진주파수 측정장치를 구성하였다. 구조용 세라믹 재료로 이용되는 $Al_{2}$O_{3}$, SiC, $Si_{3}$N_{4}$의 온도를 120$0^{\circ}C$까지 5$0^{\circ}C$의 온도간격으로 올리면서 torsional resonant frequency와 flexural resonant frequency를 측정하고, 측정된 공진주파수로부터 각 재료의 탄성계수를 구하였다. SiC의 경우는 120$0^{\circ}C$의 온도까지 탄성계수가 선형적으로 감소하였으나, $Al_{2}$O_{3}$와 $Si_{3}$N_{4}$의 경우에는 각각 100$0^{\circ}C$와 80$0^{\circ}C$까지는 선형적으로 감소하나, 그 이상의 온도에서는 탄성게수의 감소폭이 증가하는 현상을 보였다. 이러한 현상은 다결정재료에서의 grain boundary sliding에 의한 것으로 알려져 있다. 상온에서 공진법으로 측정된 동탄성계수의 측정결과는 초음파법으로 측정한 결과와 비교하였는데, 4% 내에서 서로 일치하는 결과를 보였다.

• Proceedings of the KIPE Conference
• /
• 2006.06a
• /
• pp.188-190
• /
• 2006

본 논문에서는 국내최초로 개발에 성공한 단일용량의120kW급 계통연계형 태양광발전용 PCS에 관한 내용을 설명하고 있다. 120kW급 계통연계형 태양광발전시스템은 22.9kV의 특고압 계통전원에 연계되도록 설계되었으며, 삼상 380V를 22.9kV로 승압 연계하는 2단 절연방식을 채택하였다. 120kW급 PCS는 상용주파수 변압기 절연방식으로 3상4선식 380v 60H2 출력을 가지고 있으며, PCS 내부에 120kVA급 변압기와 리액터를 포함하고 있다. 최대출력점추종(MPPT)제어 기법으로 P&O 알고리즘을 적용하였으며, 3상 IGBT 인버터를 DSP로 제어하였다. 본 논문에서는 120kW급 단일용량 PC를 개발함에 있어, 계통연계 시험, 유,무효 전류제어 시험, 단독운전 검출 및 방지시험, 출력전류의 THD 측정 등의 결과를 보이고 있다.