• 한국표면공학회지
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• 제40권1호
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• pp.39-43
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• 2007

The pure CrN powders oxidized to $Cr_2O_3$ noticeably above $850^{\circ}C$ in air. When these powders were sintered into bulk samples at $1500^{\circ}C$ under 40 atm of $N_2$ pressure, the CrN phase partly changed into the $Cr_2N$ phase, owing to the partial loss of nitrogen from CrN. When the bulk sample was heated at $1000-1200^{\circ}C$ for 100 hr under vacuum, the CrN phase also progressively changed into $Cr_2N$. At the same time, a relatively thin $Cr_2O_3$ layer formed on the bulk sample due to the reaction of chromium with residual oxygen in vacuum.

• Tribology and Lubricants
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• 제13권3호
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• pp.10-19
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• 1997

Frictional characteristics of two different types of automotive friction materials were studied. They were non-asbestos organic and semi-metallic friction materials. The two friction materials were tested using an inertial brake dynamometer to investigate friction stability, rooster tailing phenomena, temperature change during drags and stops. Results show that the level of the friction force is strong functions of time, temperature, and speed regardless of the type of friction materials. In particular, rooster tailing effects are pronounced in the case of semi-metallic friction materials compared to non-asbestos organic friction materials. The phenomena appear strongly dependent on raw materials contained in the friction materials.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.99-108
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• 2018

An oil-tolerant and salt-resistant aqueous foam system was screened out as a possible lubricant to enable cold heavy oil transportation. The microstructures and viscoelasticity and effects of heavy oil, salt and temperature on the foam stability were investigated and new rheological and drainage models were established. The results indicate the foam with multilayered shells belongs to a special microcellular foam. The viscoelasticity could be neglected due to its low relaxation time. The drainage process can be divided into three stages. The foam with quality of 67.9% maintains great stability at high oil and salt concentrations and appropriate elevated temperature.

• 대한기계학회논문집
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• 제11권1호
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• pp.145-153
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• 1987

본 논문에서는 예혼합동축분류화염에 있어서 재순환역 안으로의 기체(공기, 연료, 혼합기) 주입과 2차공기의 족회가 화염안정성, 화염형상 및 재순환역에 미치는 영향을 명확히 하였다.

• Journal of the Korean Wood Science and Technology
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• 제43권5호
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• pp.672-681
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• 2015

As a part of abating the formaldehyde emission of amino resin-bonded wood-based composite panels, this study was conducted to investigate hydrolytic stability of urea-melamine-formaldehyde (UMF) resin depending on various hydrolysis conditions and hardener types. Commercial UMF resin was cured and ground into a powdered form, and then hydrolyzed with hydrochloric acid. After the acid hydrolysis, the concentration of liberated formaldehyde in the hydrolyzed solution and mass loss of the cured UMF resins were determined to compare their hydrolytic stability. The hydrolysis of cured UMF resin increased with an increase in the acid concentration, time, and temperature and with a decrease in the smaller particle size. An optimum hydrolysis condition for the cured UMF resins was determined as $50^{\circ}C$, 90 minutes, 1.0 M hydrochloric acid and $250{\mu}m$ particle size. Hydrolysis of the UMF resin cured with different hardener types showed different degrees of the hydrolytic stability of cured UMF resins with a descending order of aluminum sulfate, ammonium chloride, and ammonium sulfate. The hydrolytic stability also decreased as the addition level of ammonium chloride increased. These results indicated that hardener types and level also had an impact on the hydrolytic stability of cured UMF resins.

• 센서학회지
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• 제17권4호
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• pp.261-266
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• 2008

In this paper, we present thermal characteristics of high-temperature measurement sensor using fiber Bragg grating(FBG), including peak reflectivity, FWHM bandwidth and various normalized refractive index change along temperature variation. The temperature stability of FBG temperature sensor can be changed by varying the refractive index change and grating length. The proposed FBG temperature sensor can measure up to about $600^{\circ}C$ and 1000 hours of heating time.

• 한국염색가공학회지
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• 제9권3호
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• pp.10-17
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• 1997

The study was performed to obtain the optimum extraction conditions for crocin from gardenia fructus. Generally crocin is unstable on heat, light, acid and base solution. The extraction efficiency of crocin from gardenia depended upon the extraction time, extraction temperature, pH in the extraction bath and the optimum conditions of crocin extraction were determined as 60 minutes of extraction time, 4$0^{\circ}C$ of extraction temperature, pH 7 of extraction bath. The molar extinction coefficient of crocin was 12,515 and the color yield of purified crocin was about six times higher than that of non-purified crocin. The heat-stability at extraction temperature and lightstability in irradiation with xenon lamp for one hour of the purified crocin were higher than those of non-purified crocin. Intensity of &{\lambda}_{max}&of crocin was decreased by irradiation for one hour but UV-Vis. spectra of crocin was not changed. The colors of purified and non-purified crocin dissolved wit methanol was evaluated by means of CIE L* a* b* system.

• 에너지공학
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• 제24권2호
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• pp.55-58
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• 2015

The mesoporous metal organic framework structure Fe-BTC was successfully synthesized by hydrothermal process with noticeable yield. The synthesis operation was conducted at intermediate temperature and for shortened operation time as compared to conventional procedures. This process approach with reduced operating temperature and shortened operation time may open an opportunity window towards process economy with reduction in energy consumption. A simple mathematical approach of diffraction indexing using X-ray diffraction patterns of synthesized powder was employed to confirm its crystalline nature and to investigate its high temperature stability. The crystallite size was calculated by using Debye-Scherrer equation.

• 한국축산식품학회지
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• 제18권4호
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• pp.358-363
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• 1998

The objectives of this study were to evaluate the effect of previous heating temperature and holding times on the thermal behavior of pork loin muscle by DSC. Pork loin muscles were heated to achieve the following end-point temperatures: 40$^{\circ}C$, 50$^{\circ}C$, 60$^{\circ}C$, 70$^{\circ}C$, 80$^{\circ}C$ at heating rate = 10$^{\circ}C$/min. The first peak was disappeared when samples were initially heated to 50$^{\circ}C$ for 1 minute. As end-point temperature was raised, major peaks were progressively disappeared and peaks were lost completely at 80$^{\circ}C$. Especially, peaks were completely disappeared at 70$^{\circ}C$ for 10 minute. Increasing of exposure time to elevated temperature also increased denaturation, thereby reducing the area of the thermogram.

• 한국미생물·생명공학회지
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• 제19권5호
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• pp.433-438
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• 1991

Phenylalanine 고생산용 plasmid pSY130-14는 $\lambda$-phage 유래 온도감수성을 가지고 있으므로 $cI_{857}$ repressor와 PL과 PR을 온도를 올려 phenylalanine의 생산을 유도한다. pSY130-14를 갖는 E.coli AT2471은 kanamycin 무첨가, $38.5^{\circ}C$, 48시간에서 약 30%로 plasmid가 없어지며 첨가에서 안정성이 떨어졌다가 배양시간과 더불어 올라갔는데, 이것은 생육에 피요한 kanamycin gene과 ori만이 남는 것으로 생각된다.