• 한국기계가공학회지
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• 제19권1호
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• pp.100-107
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• 2020

As demand for high value-added products with hard materials increases, the line center is used for producing high value-added products in many industries such as aerospace, automobile fields. The line center is a key device for smart factory automation that can improve the production efficiency and the productivity. Therefore, the development of a mill-turn line center is necessary to produce high value-added products with complex shapes flexibly. In the mill-turn process, a milling process and a turning process are combined. In particular, the turning process needs to increase the rigidity of the spindle. The purpose of this study is to analyze the thermal-structural stability through thermo-structural coupled analysis for a mill-turn spindle with a curvic coupling. The maximum temperature and thermal stability of the spindle were analyzed by thermal distribution. In addition, the thermal deformation and thermal-structural stability of the spindle were analyzed through thermo-structural coupled analysis.

• 한국염색가공학회:학술대회논문집
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• 한국염색가공학회 2008년도 제38차 학술발표대회
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• pp.192-194
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• 2008

The study has focused on the dyeing properties of 4 kinds of high temperature type mono azo disperse dyes, widely used in the dyeing factory, under the ultra low liqour ratio (1:4) dyeing condition. Among those, C.I. Disperse Red 343 and C.I. Disperse Blue 79 showed un-levelled dyeing results from the ultra low liquor ratio dyeing bath as well as poor dispersion stability under the high temperature. We recommended some leveling agents to improve the leveling behavior of these dyes mentioned above. The milling technology should be further developed to achieve the dispersion stability.

• Tribology and Lubricants
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• 제11권1호
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• pp.50-57
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• 1995

When engine oil is used under severe running condition, the Lubricational characteristics is very important. I have studied the Lubricational characteristics with Compound Additives of engine oil for the Falex wear test machine. Adding detergent (Ca-phenate) to engine oil, the seizure is more improved than in case of non-adding, and adding Zn-DTP (Zinc dialkyl dithio phosphate), the extreme pressure property is excellent at the high load. But when the PTFE (Polytetra Fluoro Ethylene) and MoS$_{2}$ (Molybdenum disulfide) are added, the temperature characteristics and the anti-wear property become excellent because the stability can be maintained in a high temperature. The result are as follows, it can be improved that when the compound of the Ca-phenate and Zn-DTP, MoS$_{2}$, PTFE, etc. was added to engine oil, the lubrication characteristics become better. It is argued that it is improved because of excellence of the anti-wear, the extreame pressure properties and the heat stability.

• 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.

• Food Science and Biotechnology
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• 제18권2호
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• pp.299-306
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• 2009

The purpose of this study was to prepare stable water-in-corn oil (W/O) emulsion droplets coated by polyglycerol polyricinoleate (PGPR). W/O emulsions (20 wt% aqueous phase, 80 wt% oil phase containing 8 wt% PGPR) were produced by high pressure homogenization (Emulsions 1), however, appreciable amount of relatively large water droplets (d>$10{\mu}m$) were found. To facilitate droplet disruption, viscosity of each phase was adjusted: (i) increased the viscosity of aqueous phase by adding 0.1 wt% xanthan (Emulsions 2); (ii) decreased the viscosity of oil phase and aqueous phase by heating them separately at $50^{\circ}C$ for 1 hr immediately before emulsification (Emulsions 3). Homogenizing at the elevated temperature clearly led to a smaller water droplet size, whereas xanthan neither improved nor adversely affected on the microstructures of the emulsions. In addition, the Emulsions 3 had good stability to droplet aggregation under shearing stress, thermal processing, and long term storage.

• 한국전기전자재료학회논문지
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• 제16권11호
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• pp.1019-1022
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• 2003

We studied the nematic liquid crystal (NLC) aligning capabilities using the new alignment material of a-C:H thin film as working gas at 30W rf bias condition. A high pretilt angle of about 5$^{\circ}$ by ion beam(IB) exposure on the a-C:H thin film surface was measured. A good LC alignment by the IB alignment method on the a-C:H thin film surface was observed at annealing temperature of 250$^{\circ}C$, and the alignment defect of the NLC was observed above annealing temperature of 300$^{\circ}C$. Consequently, the high LC pretilt angle and the good thermal stability of LC alignment by the IB alignment method on the a-C:H thin film surface as working gas at 30W rf bias condition can be achieved.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1210-1212
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• 2005

High temperature superconducting(HTS) power cable system consists of HTS cable, termination and cryogenic system. And the HTS cable consists of the former, HTS phase conductor, electric insulation, HTS shield and cryostat. Taking the advantage of HTS shield, the cold dielectric has been adopted. The phase conductor and the shield have been designed to minimize the AC loss below 1W/m/phase. The former has been designed to transport the fault current of 25kA, at fault condition. This paper describes the design process of 22.9kV HTS cable considering AC losses at normal state and the stability at fault condition.

• 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.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2891-2894
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• 2011

Recently, the rise of the rail temperature is accelerating further due to the global warming, and the track stability(buckling) problem result from the axial force in the continuous welded rail(CWR) have become the most important issue. This track stability threatens the security of running trains in the hot summer. In order to prevent the track buckling in the hot summer and ensure the safety of the running train, as a part of the safety control plan for KORAIL high-speed railway, the train speed restriction according to the rail temperature was introduced in 2004. However, the conceptual and theoretical background of train-speed restriction is uncertain. In this paper, the theoretical study about the reasonable train-speed restriction is performed. For this purpose, the risk-based probabilistic stability evaluation of the track buckling is applied.

• 한국세라믹학회지
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• 제27권2호
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• pp.226-232
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• 1990

The degradation phenomena and thermal stability of 2.5Y-TZP at low-temperature were studied by means of XRD, Raman spectra and microstructural analysis. The degradation of heat-treated 2.5Y-TZP at 20$0^{\circ}C$-20hr in air was observed on the TZP surface, be caused by the cracks generated from tlongrightarrowm transformation, and the cracks was propagated inside the polycrystalline body. The ZrO2 grain boundaries and grains near the crack were revealed as if these were diffused and dissolved. And it was also observed mlongrightarrowt transformation as the degraded TZP was refired at 140$0^{\circ}C$, and it was thought to be the fact that the moisture in atmosphere during the aging process contributed to the degradation. The thermal stability of 2.5Y-TZP was improved dramatically with an addition of 3w/o CeO2 or a provision of high Y2O3 concentration on the TZP surface.