• Journal of the East Asian Society of Dietary Life
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• v.14 no.3
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• pp.283-287
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• 2004

To investigate the effects of preheating treatment on the properties of salt-preserved cucumber, cucumber were heated in the warm water to 40, 60, and 75$^{\circ}C$ for 15 min. Thereafter, cucumbers were cooled and the ratios of cucumbers: water was adjusted to 1:1.2(w/w) and salt was added to have final salt concentration of 12%. The group which was heated to 6$0^{\circ}C$ showed the highest scores on hardness followed by 4$0^{\circ}C$, no-heat, and 75$^{\circ}C$ treated groups after 60 days of salt-preservation. The yellowness on the surface of cucumber peels was getting intense as temperature was increased during heat treatment, which resulted in the most intense yellowness in no-heat and 4$0^{\circ}C$ treated groups. The intensities of greeness and redness of the groups also differed according to different temperature applied during heat treatments. Regardless of heat treatment, no difference in the absorbance of isopropyl alcohol extracts were found. Activities of pectinesterase were the highest in 6$0^{\circ}C$ treated group followed by 4$0^{\circ}C$, 75$^{\circ}C$, and no-heat treated group until 60 days of preservation, while activities of polygalacturonase in 4$0^{\circ}C$ and 6$0^{\circ}C$ treated groups were lower.

• Journal of Food Hygiene and Safety
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• v.12 no.4
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• pp.304-309
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• 1997

A study was undertaken to determine the thermal inactivation of Escherichia coli O157:H7 as influenced by the effects of temperature, time, suspension medium and ascorbate. Tryptic soy broth was more heat resistant than pfosphate buffer (pH 7.1), with D values of 1.52~1.68 min at 6$0^{\circ}C$ and 1.51~1.63 min at 7$0^{\circ}C$ compared with 1.52~1.65 min at 6$0^{\circ}C$ and 1.26~1.61 min at 7$0^{\circ}C$ for phosphate buffer as suspension medium. E. coli O157:H7 was completely inhibited within 30 min when small inoculum (106 CFU/$m\ell$) was heated at 7$0^{\circ}C$. When E. coli O157:H7 was preheated at 48$^{\circ}C$ for 60 min in phosphate buffer before heating, D values were 1.28~1.60 min at 6$0^{\circ}C$, and 1.13~1.56 min at 7$0^{\circ}C$, showing that preheating increases the heat resistance of the strain. Phosphate buffer containing ascorbate (0.001 M) was enhanced the thermal inactivation of the strain when inoculated as large inoculum (109 CFU/$m\ell$), while ascorbic acid was no effect at low cell concentrations (109 CFU/$m\ell$).

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.433-437
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• 2005

This study was carried out the design and analysis of solar thermal system with preheating of returning district heating water for the Chung-ju district heating and cooling system. Two different types of solar collectors are used for this system. TRNSYS simulation program was used for the analysis. As a results, the solar system efficiency is $35.8\%$ for the plate type and $45.1\%$ for the evacuated type solar collector in the case of $50^{\circ}C$ for the returning district heating water temperature. The returning district heating water temperature is on of the very important factors that is influence on the system efficiency. So the effect of the returning district heating water temperature on the system efficiency is analyzed in this study.

• The Journal of Korean Medicine
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• v.16 no.1 s.29
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• pp.370-378
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• 1995

In order to consider the clinical efficacy of moxa combustion, understand the quality and quantity of heat stimulation and get the basic data for the development of electric moxibustion apparatus, the pattern of combustion temperature was measured by size of moxa(small, medium, large and maximum size). The results were as follows. 1. The pattern of combustion temperature by moxa burning was classified into input period, consisting of preheating and heating periods, and output period, consisting of heat retaining and cooling periods, in all experimental groups. But it was difficult to observe the preheating period in small sized moxa. 2. It was inclined that the more moxa size was large, the more the heating and heat retaining periods were long and the maximum temperature was high. The characteristics of moxa combustion is primarily by the rate of combustion temperature, gradient temperature and duration of combustion, and their correlation among these factors and their clinical effects in practice.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.9
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• pp.1085-1097
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• 1999

A separate heat pipe system capacity of 3,700kW has been developed and applied to preheating the blast furnace gas for recovery of the waste heat from boiler. The system is designed to preheat the blast furnace gas up to $126^{\circ}C$ by using tho boiler exhaust gas of which temperature is $180^{\circ}C{\sim}220^{\circ}C$. The arrangement of the fin tubes as well as the shape of the fin has been carefully determined to minimize the fouling problems. The heat pipe system was found to be stable in circulation of the working fluid and the range of the temperature variation of the preheated blast furnace gas was within $10^{\circ}C$. It was proved through a long-term test that the selected tube arrangement and the shape of the fins are proper to prevent the fouling problems and that the pay-back period of the system Is within one year.

• Design & Manufacturing
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• v.11 no.1
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• pp.7-13
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• 2017

The aim of this study is to develop the dies oven for energy-saving during the pre-heated process of extrusion dies. Applying high-efficiency near-infrared heater, single cell type dies oven was developed as a substitute for traditional chest type oven. Therefore the dies is individually heated uniformly to operation temperature so rapidly. By using the developed dies oven, electric-energy consumption of preheating extrusion dies reduced up to 30% and the waiting time in the oven also minimized up to 90min. In addition, the results have shown that it is possible to accurately control the dies temperature for improving the quality of extruded profile and to minimize die bearing oxidation and nitride layer degradation responsible for surface defects on the profile and shorter die life.

• Journal of the Korea Computer Industry Society
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• v.6 no.5
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• pp.741-748
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• 2005

Power saving module which is consisted of ferroelectric ceramic capacitor and time delay switching circuit was installed into electronic ballast in order to enhance energy efficacy and extend life time of fluorescent lamp. The impedance matching of negative resistance characteristics of F/L was optimized with the characteristics of ferroelectric ceramics capacitor to increase the light efficiency of the electronic ballast. The high efficiency of the electronic ballast was achieved by minimizing wasted power at the filament of F/L during the lighting by using the switching function of time delay circuit from preheating mode to non-preheating mode. The life time of F/L was also extended by eliminating the reverse electromotive force using time delay circuits to minimize the impacts to the filament of F/L from unwanted high voltage peaks during light-up period. As the results, the electronic ballast with the first grade energy efficiency was developed using ferroelectric ceramics and time delay module.

• Journal of Korea Foundry Society
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• v.26 no.2
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• pp.98-103
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• 2006

Metal-mold reactions between investment mold and TiAl alloys were investigated for the economic net-shape forming of TiAl alloys. The effect of mold preheating temperatures on the metal-mold reaction were investigated using a vacuum induction-melting furnace. In the case of TiAl alloys, there were no ${\alpha}$-case formation reactions. There were neither interstitial nor substitutional ${\alpha}$-case formations as TiAl alloys have both negligible solubility of oxygen and low activity in molten states. The fluidity of TiAl alloys increases with mold preheating temperature since they have a peritectic reaction that appears in the form of envelope, surrounding each particles of the primary constituent. The results of the investment casting of TiAl alloys confirm that the casting route in our study can be an effective approach for the economic net-shape forming of TiAl alloys.

• Journal of Korea Foundry Society
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• v.38 no.1
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• pp.16-26
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• 2018

In this study, the effects of the pouring temperature, preheating temperature, surface condition and fraction of the wear resistant part on the production of duo-castings were investigated using a high Cr white cast iron with excellent abrasion resistance and a low Cr alloy steel with good toughness. The constituent materials of the duo-castings were designed to have high hardness, fracture toughness and abrasive wear resistance for the replacement of high Mn alloy steels with low abrasive wear resistance. In particular, the amount of abrasive wear of 17% Cr white cast iron was about 1/20 of that of high Mn alloy steel. There was an intermediate area of about 3mm due to local melting at the bonding interface of the duo-castings. These intermediate regions were different from those of the constituent materials in chemical composition and microstructure. This region led to fracture within the wear resistant part rather than at the bonding interface in the bending strength test. The bending fracture strengths were 516-824 MPa, which were equivalent to the bending proof strength of high Mn steel. The effects of various casting conditions on the duo-cast behavior were studied by simple pouring of low Cr alloy steel melt, but the results proved practically impossible to manufacture duo-castings with a sound bonding interface. However, the external heating method was suitable for the production of duo-castings with a sound bonding interface.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.269-272
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• 2009

Catalytic decomposition of nitrous oxide was investigated experimentally. Two noble metal catalyst (Pt, Ir) were chosen to decompose nitrous oxide. Each catalyst was tested with different chamber pressure and preheating temperature. Ir decomposed $N_2O$ at lower temperature ($230^{\circ}C$) and suitable for $N_2O$ decomposition. In addition, the minimum required preheating temperature decreased as the chamber pressure increased. However, deactivation of Ir catalyst was observed during the experiments.