• 한국재료학회지
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• 제25권11호
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• pp.583-589
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• 2015

This paper presents a study on the room- and low-temperature impact toughness of hypoeutectoid steels with ferrite-pearlite structures. Six kinds of hypoeutectoid steel specimens were fabricated by varying the carbon content and austenitizing temperature to investigate the effect of microstructural factors such as pearlite volume fraction, interlamellar spacing, and cementite thickness on the impact toughness. The pearlite volume fraction usually increased with increasing carbon content and austenitizing temperature, while the pearlite interlamellar spacing and cementite thickness mostly decreased with increasing carbon content and austenitizing temperature. The 30C steel with medium pearlite volume fraction and higher manganese content, on the other hand, even though it had a higher volume fraction of pearlite than did the 20C steel, showed a better low-temperature toughness due to its having the lowest ductile-brittle transition temperature. This is because various microstructural factors in addition to the pearlite volume fraction largely affect the ductile-brittle transition temperature and low-temperature toughness of hypoeutectoid steels with ferrite-pearlite structure. In order to improve the room- and low-temperature impact toughness of hypoeutectoid steels with different ferrite-pearlite structures, therefore, more systematic studies are required to understand the effects of various microstructural factors on impact toughness, with a viewpoint of ductile-brittle transition temperature.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2459-2464
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• 2007

In present study, a temperature field of specimens which was coated with fluorescence dye such as Rhodamine-B(Rh-B) has been measured, based on the fluorescence intensity. Silica(SiO2) nano porous structure with 1um thickness was constructed on a cover glass, and fluorescence dye was digested into these porous thin films. To optimize manufacturing coating process, various solvents, Rh-B concentration, and other chemical materials were applied to fabricate the specimen and all specimens were measured on the various temperature conditions. For the measurement, a 14 bit cooled CCD camera with 1600 by 1200 spatial resolution is equipped with epifluorescence microscope to obtain only fluorescence intensity from 1.2 mm by 0.9 mm field of view of the illuminated coated specimen.

• Journal of Power Electronics
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• 제12권1호
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• pp.1-9
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• 2012

This study investigates an application of the Hamming network-dual extended Kalman filter (DEKF) based on pattern recognition for high accuracy state-of-charge (SOC)/capacity estimation and state-of-health (SOH) prediction at various temperatures. The averaged nine discharging/charging voltage-temperature (DCVT) patterns for ten fresh Li-Ion cells at experimental temperatures are measured as representative patterns, together with cell model parameters. Through statistical analysis, the Hamming network is applied to identify the representative pattern that matches most closely with the pattern of an arbitrary cell measured at any temperature. Based on temperature-checking process, model parameters for a representative DCVT pattern can then be applied to estimate SOC/capacity and to predict SOH of an arbitrary cell using the DEKF. This avoids the need for repeated parameter measuremet.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.579-582
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• 2005

In this study, the electrical characteristic of asymmetric high voltage MOSFET (AHVMOSFET) for display IC was investigated. Measurement data are taken over range of temperature (300K-400K) and various extended drain length, and gate oxide thickness ($175{\AA}$, $350{\AA}$). In high temperature condition, drain current decreased over 30% and max transconductance deceased over 40%, and specific on-resistance increased over 30% in comparison with room temperature.

• 산업기술연구
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• 제20권A호
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• pp.279-283
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• 2000

Lime is one of the world's most useful chemicals and manufactured in various types of kilns, using various fuels. Quicklimes vary in reactivity with water due to variations in the time and temperature calcining process and type of kiln used. Careful attention and control of time and temperature in the calcining process is necessary to insure a highly reactive lime. Excess time and temperature will cause the lime to be over burned. The highest reactivity of quicklime is obtained by calcination of limestone in the particle size of 0.1cm~2cm, calcination temperature of $1000^{\circ}C$, calcination time 90min. It was found by the scanning electron microscopes that pores of quick lime is reducted if the soft burned quick lime is heated continually.

• E2M - 전기 전자와 첨단 소재
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• 제9권2호
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• pp.196-203
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• 1996

The highly c-axis oriented zinc oxide thin films were deposited on Sapphire(0001) substrates by reactive RF magnetron sputtering. The characteristics of zinc oxide thin films on RF power, substrate-target distance, and substrate temperature were investigated by XRD, SEM and EDX analyses. The physical characteristics of zinc oxide thin films changed with various deposition conditions. The higher substrate temperatures were, The better crystallinity of zinc oxide thin films. The highly c-axis oriented zinc oxide thin films were obtained at sputter pressure 5mTorr, rf power 200W, substrate temperature 350.deg. C, substrate-target distance 5.5cm. In these conditions, the resistivity of zinc oxide thin films deposited on pt/sapphire was 12.196*10$^{9}$ [.ohm.cm].

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2003년도 ISIS 2003
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• pp.350-353
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• 2003

In this paper, we proposed the method to design fuzzy controller using the experience of the operating expert and experimental numeric data for the robust control about the noise and disturbance instead of the traditional PID controller for the main steam temperature control of the thermal power plant. The temperature of main steam temperature process has to be controlled uniformly for the stable electric power output. The process has the problem of the hunting for the cases of various disturbances. In that case, the manual action of the operator happened to be introduced in some cases. We adopted the TSK (Takagi-Sugeno-Kang) model as the fuzzy controller and designed the fuzzy rules using the informations extracted directly from the real plant and various operating condition to solve the above problems and to apply practically. We implemented the real fuzzy controller as the Function Block module in the DCS(Distributed Control System) and evaluated the feasibility through the experiment81 results of the simulation.

• Tribology and Lubricants
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• 제7권1호
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• pp.46-54
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• 1991

As the additives of engine oil, Mo-DTP and Zn-DTP were studied by experimental works. These additives were added to the engine oil with various ratios, which was an attempt to find out the best ratio at which the wear and friction can be reduced effectively; Mo-DTP is belived to be able to decrease the frictioh of the sliding metal, while Zn-DTP is known as a very stable additive for oxidation at high temperature in addition to the good antiwear property. This study showed that the optimum addition ratio of Mo-DTP and Zn-DTP is 3:2. This oil made it possible to slide steel with minimum wear and low friction over various lovels of load at moderate temperature. But as the oil temperature increased, the wear slid with Mo-DTP oil was increased more. The reason of this result was that Mo-DTP deteriorated the property of oil at high temperature by the higher oxidation and viscosity of Mo-DTP oil than that of Zn-DTP oil.

• Tribology and Lubricants
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• 제13권4호
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• pp.10-17
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• 1997

The present study describes an experimental investigation of temperature fluctuations associated with thermal instability. Surface temperatures of brake disk and pad were monitered at various locations in a caliper type brake system during drag braking conditions. It was found that the thermal instability appeared in pad more seriously than in disk. The temperatures at various circumferential positions fluctuate synchronously, whereas the center temperature fluctuates with 180$^{\circ}$ phase difference from the outer and inner radius temperatures. The temperature and amplitude of the temperature perturbations are increased due to the increase of contact area in the center location. It was also found that the thermal instability was dominantly determined by the increase of rotation speed and pressure. And the modification of ventilation path could retard the onset of thermal instability.

• Journal of Information Display
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• 제13권1호
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• pp.37-42
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• 2012

An empirical functional form was suggested for the analysis of the emission spectrum of high-power light-emitting diode (LED) consisting of a sharp blue peak from the LED chips and a broad yellow peak from the phosphor layer. The peak positions, half widths, shape parameters, and amplitudes of these two peaks were reliably obtained as a function of the temperature, and the results were discussed qualitatively in relation with the junction temperature. The adoption of an inert liquid was found to have significantly reduced the LED temperature and the color shift of the emitted light. The phenomenological approach used in this study may be helpful in the simulation of the LED spectrum under various thermal conditions, and may thus be helpful in the improvement of the device performance.