• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.11
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• pp.935-941
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• 2016

This study investigated the influence of high temperature and UNSM on the fatigue behavior of Inconel 718 alloy at RT, 300, 500, and $600^{\circ}C$. Fatigue properties of Inconel 718 were reduced at high temperatures compared to those at room temperature. However, the endurance limit was similar to that of the room temperature sample at the design stress level. High-temperature fatigue characteristics of the UNSM-treated specimen were significantly improved at the design stress level as compared to the untreated specimens. Specifically, the influence of temperature on the S-N curves at the design stress level of the UNSM-treated specimen showed the tendency of longer fatigue lives than those of untreated ones. Researchers can obtain rotary fatigue test results simply by heating specimens with a halogen lamp to precise temperatures during specific operations.

• Journal of the Korean Wood Science and Technology
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• v.46 no.3
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• pp.285-296
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• 2018

As a study for the verification of heat treated wood according to ISPM No. 15, the spectroscopic characteristics of the heat treated wood surface were analyzed. Various functional groups were observed on the IR spectrum, but it was difficult to find any particular difference between wood species, heat treatment time and storage period. HBI (hydrogen-bonding intensity) shows the change of the heat treated wood according to the storage time, but the change of wood with the heat treatment time was hard to be observed. On the PCA score plot, however, it was possible to sort the wood according to the heat treatment time of 60 minutes or 90 minutes in the species. The standards for classification of heat-treated wood in PCA were aromatic rings in lignin and C-H bending in cellulose, and these components were able to classify heat-treated wood by ISPM No. 15.

• Korean Journal of Food Science and Technology
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• v.40 no.2
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• pp.166-170
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• 2008

The effects of heat treatments on the antioxidant activities of selected fruits and vegetables were investigated by heating at various temperatures (110, 120, 130, 140, and 150$^{\circ}C$) for 2 hr. The examined fruits and vegetables included tomatoes (Lycopersicon esculentum), oriental melon (Cucumis melon var. makuwa), apples (Malus pumila Miller var. domestica Schneider), melon (Cucumis melon), watermelon (Citrullus vulgaris), and banana (Musa sapientum). The total polyphenol and total flavonoid contents of the juices from heated samples were quantified spectrophotometrically, and their antioxidant activities were determined using DPPH and ABTS radicals. As the heating temperature increased, antioxidant activity also increased. The highest total polyphenol content (2.80 mg/g) occurred in the oriental melon with heating at 150$^{\circ}C$, and this value was 7 times higher than that of the untreated oriental melon (0.40 mg/g). The highest total flavonoid content (148.80 ${\mu}$g/g) occurred in the melon heat treated at 150$^{\circ}C$, and this value was 37 times higher than that of the untreated melon (4.54 ${\mu}$g/g). DPPH radical-scavenging activity was the highest in the watermelon treated at 150$^{\circ}C$ (84.37%, 0.50 mg/g), and this value was 40 times higher than that of the untreated watermelon. Finally, the highest ascorbic acid (AA) equivalent antioxidant capacity (AEAC) value (239.50 mg AA eq/g) was obtained in the watermelon heat treated at 150$^{\circ}C$ for 2 hr (control = 18.35 mg AA eq/g).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.17 no.2
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• pp.93-103
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• 1981

It is well-known that nowadays heat resisting and anti-corrosive materials have been widely used as the components materials of gas turbines, nuclear power plants and engines etc. In the fields of machine production industry. And materials for engine components, like as the exhaust valve of internal combustion engine, have been required to operate under the high temperature range of $700^{\circ}C$-$800^{\circ}C$ and high pressured gas with repeated mechanical load for the high performance of engines. For these components, friction welding for bonding of dissimilar steels can be applied for in order to obtain process shortening, production cost reduction and excellent bonding quality. And age hardening recently has been noticed to the heat resisting materials for further strengthening of high temperature strength, especially high temperature fatigue strength. However, it is difficult to find out any report concerning the effects of age hardening for strengthening high temperature fatigue strength to the Friction welded heat resisting and anti-corrosive materials. In this study the experiment was carried out as the high temperature rotary bending fatigue testing under the condition of $700^{\circ}C$ high temperature to the friction welded domestic heat resisting steels, SUH3-SUS303, which were 10hr., 100hr. aging heat treated at $700^{\circ}C$ after solution treatment 1hr. at $1, 060^{\circ}C$ for the purpose of observing the effects of the high temperature fatigue strength and fatigue fracture behaviors as well as with various mechanical properties of welded joints. The results obtained are summarized as follows: 1) Through mechanical tests and micro-structural examinations, the determined optimum welding conditions, rotating speed 2420 rpm, heating pressure 8kg/mm super(2), upsetting pressure 22kg/mm super(2), the amount of total upset 7mm (heating time 3 sec and upsetting time 2 sec) were satisfied. 2) The solution treated material SUH 3, SUS 303, have the highest inclination gradient on S-N curve due to the high temperature fatigue testing for long time at $700^{\circ}C$. 3) The optimum aging time of friction welded SUH3-SUS 303, has been recognized near the 10hr. at $700^{\circ}C$ after the solution treatment of 1hr. at $1, 060^{\circ}C$. 4) The high temperature fatigue limits of aging treated materials were compared with those of raw material according to the extender of aging time, on 10hr. aging, fatigue limits were increased by SUH 3 75.4%, SUS 303 28.5%, friction welded joints SUH 3-SUS 303 44.2% and 100hr. aging the rates were 64.9%, 30.4% and 36.6% respectively. 5) The fatigue fractures occurred at the side of the base matal SUS303 of the friction welded joints SUH 3-SUS 303 and it is difficult to find out fractures at the friction welding interfaces. 6) The cracking mode of SUS 303, SUH 3-303 is intergranular in any case, but SUH 3 is fractured by transgranular cracking.

• Journal of the Korean Ceramic Society
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• v.22 no.3
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• pp.35-40
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• 1985

The composition of the base glass was determined to be $Na_2O$ 15, $Fe_2O_3$ 35, $B_2O_3$ 0~20, $P_2O_5$ 30~50 by mole percent. The heating temperature for nucleation was determined by means of thermal expansion curve. Crystalline phases were investigated by X-ray diffraction method and I.R Spectra. Electrical conductivities of glass spec-imens were observed in the temperature range 25~20$0^{\circ}C$ The activation energies of these specimens were caculated. The results obtained were as follows : 1) The limit composition of the melts 15mol% $Na_2O$ 35mole% $Fe_2O_5$ 20mole% $B_2O_3$ 30mole% $P_2O_5$ was able to be formed into desired shapes during cooling, . 2) In the measurement of d. c conductivity($\delta$) on the glasses in the system $15Na_2O-35Fe_2O_3$-$B_2O_3$-(50-x) $P_2O_5$ the values decreased by replacing 5 mole% $P_2O_5$ with $B_2O_3$ 3) The d. c conducties of heat treated samples were increased by replacing $P_2O_5$ with $B_2O_3$ 4) $B_2O_3$ contributed to precipitate crystals such as${\gamma}$-$Fe_2O_3$ $Fe_3O_4$ which had the advantage of electronic conduction in heat treated samples. 5) The slope plotted Log($\delta$) versus 1/T in this glass system was linear in the measured temperature range.

• Journal of the Korean Wood Science and Technology
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• v.38 no.1
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• pp.17-26
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• 2010

Recently, yellow poplar (Liriodendron tulipifera L.) is getting attention in Korea due to the fast growing and high yield and quality of lumber. But, it is thought that the color difference between heartwood and sapwood may restrict the practical use of it. This study was aimed to enhance the value of yellow poplar lumber by the color control using high temperature heat-treatment, which had been tried for domestic cedar (Kim et al., 2009). The material properties including surface color of yellow poplar lumber were evaluated according to heat treatment conditions. The difference of color between sapwood and heartwood could be reduced by heat treatment at a temperature about $200^{\circ}C$. Long heating time was more effective in reducing the difference. The Equilibrium Moisture Content (EMC) of heat-treated wood was as low as 50 percent of the control. The result obviously indicates that heat-treated wood is more dimensionally stable in the change of moisture condition. The durability against wood rotting fungi also increased by the heat-treated, but it was not so effective as the case of cedar. The changes of mechanical properties of heat-treated yellow poplar were very similar to that of heat-treated cedar. In order to develop new use of heat-treated yellow poplar, the changes of mechanical properties should be considered. There were no significant changes in microscopic structure which may cause changes in mechanical properties. Further study of heat-treated wood is needed to scrutinize the causes of changes of material properties.

• The Korean Journal of Ecology
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• v.18 no.3
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• pp.333-340
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• 1995

This study aims to examine how the amount of sample and changes in combustible temperature of living branches and leaves treated with high temperature are associated with combustible time of two coniferous trees, Pinus rigida (R) and Larix leptolepis (L), which are the main victims of forest fire. During the first thirty minutes at $80^{\circ}C$, moisture content of R was higher than that of L by 12%, but after four hours, the moisture content was both lowered by 4~5% and turned to highly combustible leaves. With living leaves, the maximal combustible temperature, regardless of heating temperature, turned out to be higher than normal temperature by $67~140^{\circ}C$, and that with living branches, it was higher by $113~207^{\circ}C$. Also, with living leaves (R, L), the duration time of combustion was as follows: 605, 906 seconds at $400^{\circ}C$ and 76, 227 seconds at $600^{\circ}C$, respectively. Concerning the relation between the amount of burnt fuel and maximal temperature, the more the former was, the higher the latter. The total amounts of combustion heat of living branches and living leaves were 1, 121 Cal (20.8%) and 1, 137 Cal (21.4%), respectively. The total amount of combustion heat increased in proportion to the amount of consumed fuel: 100 g of living leaves and branches gave rise to 128 Cal, whereas 300 g did 556 Cal, that was more than three times.

• Archives of Plastic Surgery
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• v.42 no.2
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• pp.173-178
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• 2015

Background Various focal heating devices are popular in Korea under the cultural influence of the traditional ondol under-floor method of home heating. These devices can cause severe burn-like injuries resulting from device malfunction or extended with low heat contact. In addition to injuries under these high heat contact, burns can be occurred by low heat exposure with prolonged periods despite the devices are properly functioning. In order to develop strategies to reduce the duration of periods of illness due to low-temperature burns, we analyzed and compared treatment methods and therapeutic periods for this type of injury. Methods This retrospective study included 43 patients burned under low heat conditions. Patients were divided into an operative group and a conservative group. The patients in the operative group underwent at least one surgical excision, and were further subdivided into early and late visit groups. The conservative group was treated only with dressings. We compared the treatment periods between the operative group and the conservative group, and also compared the preparation periods and treatment periods between the two operative groups. Results The average treatment period was significantly shorter in the operative group (P=0.02). In the early visit operative group, both wound preparation and treatment were briefer than in the late visit group. Conclusions We recommend that early proper burn care and early surgical intervention, including appropriate excision, are feasible ways to reduce the treatment period of lowtemperature burn patients.

• Journal of the Korean Wood Science and Technology
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• v.35 no.6
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• pp.50-56
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• 2007

FAO standard for heat sterilization of wood, International standards for phytosanitary measures (ISPM) No.15, must meet heat-treated wood core temperature to be higher than $56^{\circ}C$ and keep the temperature for more than 30 minutes. This study was carried out to analyze the heat treatment characteristics of domestic pinewood sterilized with the FAO standard. To enhance the effectiveness of heat treatment process in mountainous district energy consumption and time required to reach target temperature were evaluated at various temperature and relative humidity conditions and moisture contents of wood. Heat-treatment of high temperature and high humidity reduced the required heating time. Lower humidity levels at same temperature reduced energy consumption per unit time. However, lower humidity levels could not reduce total energy consumption greatly because longer treatment time was required at that condition. It is necessary to estimate energy consumption and predict treatment time in dynamic heating and cooling situations, because it frequently happens not to meet optimum treatment condition due to poor surrounding climates and operation performance of heat treatment facility in real field.

• Journal of the Korean Society of Food Science and Nutrition
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• v.15 no.1
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• pp.22-26
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• 1986

This investigation was carried out to study the effect of heating treatment on the saponin fractions in ginseng extract and crude saponin. The changes of saponin patterns and amounts were investigated using HPLC and compared with peak area of each fraction. Shape of crude saponin was changed more easy to compare with in ginseng extract. The more extracting temperature risen and treated time longer, the more changes of saponin amounts and patterns were shown, expecially at $100^{\circ}C$ over. All of the saponin fraction except ginsenoside-Rd were relatively unstable in heating treatment. Suitable extracting condition was extracted at $80^{\circ}C$ for 40 hours with $H_2O$.