• Journal of the Korean Society of Food Science and Nutrition
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• v.13 no.3
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• pp.313-318
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• 1984

Some chemical, biochemical and physical treatments on the baker's yeasts (Saccharomyces cerevisiae) before 12-hour digestion at $50^{\circ}C$ were made to accelerate their autolysis. Dilute alkali treatment with 0.01N-NaOH solution showed a considerable increase in soluble nitrogen extraction only in the 6-hour initial autolysis. The addition of fresh yeast autolysate, 10% to the yeast slurry, could increase the autolysis rate from 65% to 83%. Microwave treatment of yeast slurry for 40 seconds also raised the autolysis rate by about 15%, while longer exposures to the microwave accompanying high temperatures repressed the autolysis process. Extrusion of the yeast cells with high pressures of 16,000 to 20,000 psi brought about significantly higher autolysis rate until the digestion time of 9 hours, but thereafter it showed a gradual drop in soluble nitrogen extraction.

• Journal of the Korean Institute of Gas
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• v.21 no.2
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• pp.26-31
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• 2017

The purpose of this paper is to study for turbocharger system in a vehicle of diesel engine. The first example, it certified the fact that a car engine is not to accelerate by clogged the exhaust tube as the turbine was damaged because of turbine wheel broken. The a vehicle with turbocharger must to stop engine operation after maintaining the appropriate idle revolution as it can be the sticking phenomenon if the operator immediately stop the engine being high revolution. The second example, it knew the phenomenon of acceleration faulty that the rod of VGT actuator that operating the turbocharger adhered with the bracket of VGT. The third example, it confirmed the power insufficiency phenomenon when driving by of alternator resistor and fan intercooler fan relay connector mistaken assembly. Therefore, the operator have to scrutinize manage no the failure of turbocharger system.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.2
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• pp.71-79
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• 2010

As hypersonic flight speeds and engines efficiencies increase, heat loads on an aircraft and it's engine increase. Because the temperature of the air flow is too high to cool the aircraft structure at hypersonic flight speeds, it is essential to use the aircraft fuel as the primary coolant. Endothermic fuels are liquid hydrocarbon aircraft fuels which are able to absorb the heat loads by undergoing endothermic reactions, such as thermal and catalytic cracking. The endothermic reactions are improved by catalysts which change the extent of reaction and product distribution. At high temperature, liquid hydrocarbons would lead to coke formation that can reduce the effectiveness of heat exchanger and cause rapid degradation of the catalyst, thus endothermic capacity of endothermic fuels is limited to the temperature at which coke doesn't form. In this study, the essential cooling technologies by applying endothermic fuels and the properties of the endothermic fuels are described.

• Journal of the Korean Ceramic Society
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• v.28 no.8
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• pp.625-625
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• 1991

The specimens for the corrosion test were made by hot-pressing of SiC power with 2 wt% Nl2O3 and 10wt% Al2O3 additions at 2000℃ and 2050℃. The specimens were corroded in 37 mole% NaCl and 63 mole% Na2SO4 salt mixture at 1000℃ up to 60 min. SiO2 layer was formed on SiC and then this oxide layer was dissolved by Na2O ion in the salt mixture. The rate of corrosion of the specimen containing 10 wt% Al2O3 was slower than that of the specimen containing 2 wt% Al2O3. This is due to the presence of continuous grain boundary phase in the specimen containing 10 wt% Al2O3. The oxidation of SiC produced gas bubbles at the SiC-SiO2 interface. The rate of corrosion follows a linear rate law up to 50 min. and then was accelerated. This acceleration is due to the disruption oxide layer by the gas evolution at SiC-SiO2 interface. Pitting corrosion has found at open pores and grain boundaries.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.3
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• pp.43-49
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• 2016

Reliability characteristics of thin package-on-packages were evaluated using T/H (temperature/humidity) test at $85^{\circ}C/85%$ for 500 hours, TC (temperature cycling) test at $-40{\sim}100^{\circ}C$ for 1,000 cycles, and HTS (high temperature storage) test at $155^{\circ}C$ for 1,000 hours. The average resistance of the solder-bump circuitry between the top and bottom packages of 24 package-on-package (PoP) samples, which were processed using polyimide thermal tape, was $0.56{\pm}0.05{\Omega}$ and quite similar for all 24 samples. Open failure of solder joints did not occur after T/H test for 500 hours, TC test for 1,000 cycles, and HTS test for 1,000 hours, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.336-337
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• 2007

현재 투명전극의 재료로 ITO, ZnO, $SnO_2$등의 재료가 주로 이용되며, 낮은 저항률을 장점으로 가지는 ITO 박막이 가장 널리 이용되고 있으나, 가격이 비싸다는 단점을 가지고 있다. 이 밖에도 ITO 박막보다 가격이 저렴한 ZnO박막에 대한 연구가 많이 진행되고 있으나, 고온에서의 열적 불안정성 등의 문제로 상용화되지는 못하고 있다. 그러나 $SnO_2$ 박막은 ITO와 ZnO 박막보다 저항률이 다소 높지만, 우수한 열적, 화학적 안정성과 저렴한 가격으로 ITO 박막을 대체할 투명전도막 재료로 주목받고 있다. 본 연구에서는 $SnO_2$박막의 저항률 향상을 위하여 ATO(Antimony doped Tin Oxide) 박막을 RF Magnetron Sputtering 법으로 Coming glass위에 증착하였으며, 박막 증착시 산소 유량의 변화가 ATO 박막의 구조적, 전기적 그리고 광학적 특성에 미치는 효과를 연구하였다. 본 실험에서는 동작압력을 10 mTorr, RF power를 250W로 고정하고 $O_2$ 유량을 부분적으로 변화시키면서 증착되어진 ATO 박막을 분석한 결과 Ar:$O_2$의 비가 90:10일 때 최적의 가스비율로써 우수한 구조적, 전기적 그리고 광학적 특성을 보임을 확인하였다.

• Korean Journal of Materials Research
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• v.22 no.10
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• pp.499-503
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• 2012

The present study is intended to comparatively investigate the changes in microstructure and tensile properties at room and elevated temperatures in commercial AM50(Mg-5%Al-0.3%Mn) and 0.3 wt%CaO added ECO-AM50 alloys produced by permanent mould casting. The typical microstructure of AM50 alloy was distinctively characterized using two intermetallic compounds, ${\beta}(Mg_{17}Al_{12})$ and $Al_8Mn_5$, along with ${\alpha}$-(Mg) matrix in an as-cast state. The addition of a small amount of CaO played a role in reducing dendrite cell size and quantity of the ${\beta}$ phase in the AM50 alloy. It is interesting to note that the added CaO introduced a small amount of $Al_2Ca$ adjacent to the ${\beta}$ compounds, and that inhomogeneous enrichment of elemental Ca was observed within the ${\beta}$ phase. The ECO-AM50 alloy showed higher hardness and better YS and UTS at room temperature than did the AM50 alloy, which characteristics can be mainly ascribed to the finer-grained microstructure that originated from the CaO addition. At $175^{\circ}C$, higher levels of YS and UTS and higher elongation were obtained for the ECO-AM50 alloy, demonstrating that even 0.3 wt%CaO addition can be beneficial in promoting the heat resistance of the AM50 alloy. The combinational contributions of enhanced thermal stability of the Ca-containing ${\beta}$ phase and the introduction of a stable $Al_2Ca$ phase with high melting point are thought to be responsible for the improvement of the high temperature tensile properties in the ECO-AM50 alloy.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.2
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• pp.157-162
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• 2011

High temperature and stress are encounted in power plants and vehicle engines. Therefore, determination of the creep-fatigue life of a material is necessary prior to fabricating equipments. In this study, life design was determined on the basis of the lethargy coefficient for different temperatures, stress and rupture times. SP-Creep test data was compared with computed data. The SP-Creep test was performed to obtain the rupture time for X20CrMoV121 steel. The integration life equation was considered for three cases with various load, temperature and load-temperature. First, the lethargy coefficient was calculated by using the obtained rupture stress and the rupture time that were determined by carrying out the SP-Creep test. Next, life was predicted on the basis of the temperature condition. Finally, it was observed that life decreases considerably due to the coupling effect that results when fatigue and creep occur simultaneously.

• FLOWER RESEARCH JOURNAL
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• v.17 no.4
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• pp.266-270
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• 2009

This experiment was conducted to investigate the effect of transfer date to a growth chamber and low temperature on growth and flowering of Jeffersonia dubia for free control of flowering period. According to transfer date, any plant did not sprout when plants were put in a growth chamber from Aug. 20 to Dec. 20. However, all the plants which were put in a growth chamber on Jan. 20 or Feb. 20 sprouted and resulted in flowering. The effect of beginning time and period of low temperature treatment were also observed. At the beginning time of Aug. 20, sprouting and flowering occurred as plant received more than 60 days of low temperature treatment. However, almost of al l the plants sprouted and flowered by only 30 days of low temperature treatment when the low temperature was given after Sep. 20. 60 days of low temperature given again after about three month growing period after dormancy breaking, resulted in resprouting of all plants and 70% of them flowered in this experiment.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.2
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• pp.31-38
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• 2013

This research analyzed the acoustic emission signals collected from the pin loading tests and investigated the effect of hygrothermal exposure on the fracture behavior of the pin-jointed carbon fiber/epoxy composites. The composite specimens include: the Base specimen that has not been exposed to any environments, the RT specimen that has been immersed in room temperature water, and the HT specimen that has been immersed in high temperature water. According to the pin loading test, the RT and the HT specimens showed 2.2% and 13% decreases in the bearing strength compared to the Base specimen, respectively. The analysis of the acoustic emission signals showed different fracture acceleration points for three types of the specimens. Furthermore, for the RT and the HT specimens, the event from the matrix crack signals in the composites decreased. This shows the effect of the hygrothermal conditions on the acoustic emission signals. Additionally, upon investigating the fracture behaviors of the pin-jointed composites, the exposing specimens to hygrothermal environments decreases the interfacial characteristics of the composites.