• 대한치과기공학회지
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• 제38권2호
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• pp.69-77
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• 2016

Purpose: This study was to evaluate the shear bond strength of ceramic fused to Ni-Cr alloy(Alophaloy) by heat treatment. Methods: The specimens were divided into 5 groups according to heat treatment conditions prior to porcelain application. Eighteen specimens from each group were subjected to the shear load a universal testing machine using a 0.1mm/min cross-head speed and two specimens from each group were observed with SEM and EDX line profile. Results: The observation of the oxide film on the metal surface by SEM photograph showed a coarsening with an increasing degassing hold time. The diffusion of metal oxide was observed farther from the opaque layer in the heat treated specimen than no heat treated specimen. The shear bond strength measured highest to A5(55.23MPa) in the 10min holding group and measured lowest from A1(24.38MPa) in the no heat treated group, and there was a significant difference(p<0.05). Conclusion: The shear bond strength of Ni-Cr alloy improved in the heat treatment compared to the no heat treatment specimen.

• 한국재료학회지
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• 제24권9호
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• pp.465-468
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• 2014

The crystallization effects of boron (B) powder on the phase, full width at half maximum (FWHM) values, and critical properties were investigated for in-situ reacted $MgB_2$ bulk superconductors. The semi-crystalline B powder was heat-treated at different temperatures of 1000, 1300 and $1500^{\circ}C$ for 5 hours in an Ar atmosphere. Then, using as-received and heat-treated B powders, the $MgB_2$ samples were prepared at $600^{\circ}C$ for 40 hours in an Ar atmosphere. As the heat-treatment temperature of the B powder increased, both the particle size of the B powder and crystalline phase increased. In the case of $MgB_2$ samples using B powders heat-treated at above $1300^{\circ}C$, unreacted magnesium (Mg) and B remained due to the improved crystallinity of the B powder. As the heat-treatment temperature of B powder increased, the critical current density of $MgB_2$ decreased continuously due to the reduction of grain boundary density and superconducting volume caused by unreacted Mg and B.

• 한국분말재료학회지
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• 제22권1호
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• pp.32-38
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• 2015

The effect of heat treatment environment on the microstructure and properties of tantalum coating layer manufactured by kinetic spraying was examined. Heat treatments are conducted for one hour at $800^{\circ}C$, $900^{\circ}C$, and $1000^{\circ}C$ in two different environments of vacuum and Ar gas. Evaluation of microstructure and physical properties are conducted. High density ${\alpha}$-tantalum single phase coating layer with a porosity of 0.04% and hardness of 550 Hv can be obtained. As heat treatment temperature increases, porosity identically decreases regardless of heat treatment environment (vacuum and Ar gas). Hardness of heat treated coating layer especially in Ar gas environment deceases from 550 Hv to 490 Hv with increasing heat treatment temperature. That in vacuum environment deceases from 550 Hv to 530 Hv. The boundary between particles became vague as heat treatment temperature increases. Oxygen distribution of tantalum coating layer is minute after heat treatment in vacuum environment than Ar gas environment.

• 한국세라믹학회지
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• 제29권2호
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• pp.152-160
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• 1992

High-Tc superconductor thick films of YBa2Cu$\chi$O7-y (X=3, 3.5, 4) of which thickness varies from 100 $\mu\textrm{m}$ to 200 $\mu\textrm{m}$ were successfully prepared by plasma spraying method, and the characteristics of thick film depending on copper content and heat treatment conditions were investigated. Regardless of heat-treated temperature, the specimens with X=3 were composed of YBa2Cu$\chi$O7-y, Y2BaCuO5 and BaCuO3 phases. The specimens with X=4, however, were composed of YBa2Cu$\chi$O7-y phase at all heat treatment conditions. The specimens with X=4 composition showed the best superconducting characteristics after heat treatment at 925$^{\circ}C$, and the superconducting transition temperature with zero resistivity (Tc,zero) was 87K. The thick film lost superconductivity when the specimens were heat-treated at 950$^{\circ}C$ because of interdiffusion between superconductor elements and bond coating elements and Y2BaCuO5 phase was found was found to be main phase at the interface.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1991년도 추계학술대회 논문집
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• pp.80-86
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• 1991

In this study an the development of the heat flux sensor with thermocouple, the heat-treated adhesive type film nickel gauge(Ni-Gauge) for measuring temperature was used. and this Ni-Gauge is not only comparable for platinum gauge(Pt-Gauge) in linearity, but also economically cheap. And from this viewpoint. numerical analysis is essential to investigate charateristics of sensor, since this analysis is capable of simulating precise boudary condition and practical conditions and so on. By the way. there are many types of heat flux sensor. of which adhesive type flux sensor is common, in the study this type of heat flux sensor was chogen. and analysis of the sensor is considered as a kind of open cavity figure. performed by SIMPLER algorithm. As a result. through temperature distributial of the sensor by numerical analysis in steady and unsteady state, the dracteristics of the acdhesive type heat flux sensor(lst heat flux sensor) acooodinge to heat flux, that is, outvoltage, sensitivity. and responsibilty could be evaluated. in addition, time of improved heat flux sensor(2nd heat flux sensor) could be predicted fran the reflectian of proper operating temperature(l50 $^{\circ}C$)of theNi-Gauge.

• Journal of Ginseng Research
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• 제43권2호
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• pp.252-260
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• 2019

Background: Increases in the average global temperature cause heat stress-induced disorders by disrupting homeostasis. Excessive heat stress triggers an imbalance in the immune system; thus protection against heat stress is important to maintain immune homeostasis. Korean ginseng (Panax ginseng Meyer) has been used as a herbal medicine and displays beneficial biological properties. Methods: We investigated the protective effects of Korean ginseng extracts (KGEs) against heat stress in a rat model. Following acclimatization for 1 week, rats were housed at room temperature for 2 weeks and then exposed to heat stress ($40^{\circ}C$/2 h/day) for 4 weeks. Rats were treated with three KGEs from the beginning of the second week to the end of the experiment. Results: Heat stress dramatically increased secretion of inflammatory factors, and this was significantly reduced in the KGE-treated groups. Levels of inflammatory factors such as heat shock protein 70, interleukin 6, inducible nitric oxide synthase, and tumor necrosis factor-alpha were increased in the spleen and muscle upon heat stress. KGEs inhibited these increases by down-regulating heat shock protein 70 and the associated nuclear $factor-{\kappa}B$ and mitogen-activated protein kinase signaling pathways. Consequently, KGEs suppressed activation of T-cells and B-cells. Conclusion: KGEs suppress the immune response upon heat stress and decrease the production of inflammatory cytokines in muscle and spleen. We suggest that KGEs protect against heat stress by inhibiting inflammation and maintaining immune homeostasis.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 추계학술대회 논문집
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• pp.29-32
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• 2000

The static and metadynamic recrystallization of non-heat treated medium carbon steel(Fe - 0.45wt.$\%C\;-\;0.6wt.\%Si\;-\;1.2wt.\%Mn\;-\;-0.12wt.\%Cr \;-\;0.1wt.\%V \;-\;0.017wt\%$.Ti) were studied by the torsion test in the strain rate range of 0.05 - 5 $sec^{-1}$, and in the temperature range of $900\;-\;1100\;^{\circ}C$. Interrupted deformation was performed with 2 pass deformation in the pass strain range of $0.25 {\varepsilon}_p(peak strain)\;and\;{\varepsilon}_p$, and in the interpass time range or 0.5 - 100 sec. The dependence or pass strain(${\varepsilon}_i$), strain rate( $\dot{\varepsilon}$ ), temperature(T), and interpass time($t_i$) on static recrystallization (SRX) and metadynamic recrystallization (MDRX) were predicted from the modified Avrami's equations respectively. Comparison of the softening kinetics between SRX and MDRX was indicated that the rate of MDRX was more rapid than that of SRX under the same deformation variables.

• 한국식품영양과학회지
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• 제41권2호
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• pp.278-282
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• 2012

고온고압처리와 마이크로파 처리, 증자처리 하여 제조된 마늘의 이화학적 및 항산화활성 변화를 조사하였다. 열처리 방법에 따른 마늘의 물성은 고온고압처리를 한 후 $60^{\circ}C$에서48시간 건조한 마늘은 hardness와 softness는 증가하는 경향을 보였고 strength는 감소하는 경향을 보였다. 생마늘과 비교해 볼 때 마이크로파 처리와 증자처리 마늘의 hardness와 strength는 감소하는 경향을 보였고 처리시간이 증가할 수록 감소하는 경향을 보였다. 생마늘의 환원당 함량은 0.041 g/100 g으로 나타났으며, 고온고압처리 마늘의 환원당 함량은 처리온도가 증가할수록 증가하는 경향을 보였다. 열처리 방법에 따른 마늘이 폴리페놀 함량은 고온고압처리 온도가 증가할수록 증가한 경향을 보였고 마이크로파 처리 및 증자 처리의 경우 생마늘에 비해 감소하는 경향을 보이는 것으로 나타났다. 열처리 방법에 따른 마늘의 DPPH radical 소거활성은 생마늘의 경우 3.07 mg/mL을 나타내었으며, 마이크로파 처리의 경우 4분 처리 시료가 2.16 mg/mL로 가장 높은 활성을 보였다. ABTS radical 소거활성은 생마늘의 경우 40.94 mg AEAC/mL로 나타났으며, $150^{\circ}C$, 2시간 처리 마늘이 76.51 mg AEAC/mL로 가장 높은 활성을 보였다.

• 한국분말재료학회지
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• 제24권2호
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• pp.133-140
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• 2017

This study investigates the oxidation properties of Fe-14Cr ferritic oxide-dispersion-strengthened (ODS) steel at various high temperatures (900, 1000, and $1100^{\circ}C$ for 24 h). The initial microstructure shows that no clear structural change occurs even under high-temperature heat treatment, and the average measured grain size is 0.4 and $1.1{\mu}m$ for the as-fabricated and heat-treated specimens, respectively. Y-Ti-O nanoclusters 10-50 nm in size are observed. High-temperature oxidation results show that the weight increases by 0.27 and $0.29mg/cm^2$ for the as-fabricated and heat-treated ($900^{\circ}C$) specimens, and by 0.47 and $0.50mg/cm^2$ for the as-fabricated and heat-treated ($1000^{\circ}C$) specimens, respectively. Further, after 24 h oxidation tests, the weight increases by 56.50 and $100.60mg/cm^2$ for the as-fabricated and heat-treated ($1100^{\circ}C$) specimens, respectively; the latter increase is approximately 100 times higher than that at $1000^{\circ}C$. Observation of the surface after the oxidation test shows that $Cr_2O_3$ is the main oxide on a specimen tested at $1000^{\circ}C$, whereas $Fe_2O_3$ and $Fe_3O_4$ phases also form on a specimen tested at $1100^{\circ}C$, where the weight increases rapidly. The high-temperature oxidation behavior of Fe-14Cr ODS steel is confirmed to be dominated by changes in the $Cr_2O_3$ layer and generation of Fe-based oxides through evaporation.

• The Korean Journal of Ecology
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• 제18권4호
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• pp.483-491
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• 1995

This study examined the relationship among catch-fire, burning, maximum temperature (MT), amount of combustion-heat (ACH), and combustive time (CT) in heating temperature treated with the same amount of each organ of Miscanthus. In the survey sites, about 19％ of the areaswere covered by Miscanthus types, and the dry weight of Miscanthus and debris on the ground were 1,164 and 178 g/㎡, respectively. At 350℃ and 400℃, the rise of temperature by Culm type (culms and ears) and Leaf type (leaves and debris) were 90℃ and 82℃, respectively. At 350℃, durning time (BT) of culms-200, ears-200, ears-200, leaves-200 and debris-200 was 0-10’30”, 0-07’40”, 0-04’20”and 0-02’40”, and that at 400℃ was 0-01’20”, 0-00’50” 0-00’35”and 0-00’30”, respectively. BT was shorter at higher temperatures, and BT of Leaf type was shorter than that of Culm type. The amount of samples consumed was as follows: Culm type (culms-200 and ears-200) was 14.6g and 12.6g more than Leaf type (leaves-200 and debris-200) at 350℃ and 400℃, respectively. The total amount of combustion-heat (TACH) of samples was 5,859.7 kcal. The amount of mean combustion-heat generated from sample at 350℃ and 400℃ differed little: 727.6 kcal (24.9％) at 350℃ and 737.3 kcal (26.0％) at 400℃.