• Journal of ILASS-Korea
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• v.25 no.2
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• pp.74-80
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• 2020

The jet in crossflow is a spray method used in the various air-breathing engine. In order to understand the spray characteristics in various environments, many prior studies have been conducted. However, there is a lack of understanding of the low-temperature liquid spray characteristics below 273 K. With this in mind, we tried to enhance the knowledge of the low-temperature liquid spray characteristics by identifying the penetration height of low-temperature ethanol. The experiment was conducted under phase pressure, and 273 K of air and 293, 263, and 233 K of ethanol was used. Shadowgraphy was employed to measure the liquid penetration, and Otsu's method was used to analyze the penetration height. The heights tend to decrease as the temperature of the liquid jet decreases. A correlation for the penetration height in the experimental conditions was derived and presented.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1418-1423
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• 2009

This study describes experimental study on the performance characteristics with load condition in hybrid solar heating system during spring season. The room temperatures, the hot water conditions and the lower part temperatures of heat storage tank were changed to analyze the system performances. As a results, the hot water was significantly affected by the ambient temperature. The indoor setting temperature affected the solar fraction. When the low part temperature of the storage tank increased, the temperature of the hot water rose and the temperature of the hot water in morning was affected by the ambient temperature.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.3
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• pp.239-247
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• 2009

In AC-PDP, it is necessary to achieve high luminance efficacy, high luminance and high resolution by adopting technologies such as high Xenon concentration, MgO doping, and long gap. However, it is very difficult to apply above technologies because they reduce driving voltage margin. For example, doping of MgO reduces driving voltage but introduces new problems such as increased temperature dependency of discharge, which result in larger variations in driving margin at different temperatures. In this paper, we present the experimental results of the characteristics of temperature-dependent discharges. In addition, we suggest the mechanism of bright noise, black noise, and high temperature mis-discharge, which depend on temperature-dependent characteristics of MgO.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.342-344
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• 1995

Using piezoresistive effects of single-crystal and poly-crystalline silicon, pressure sensors of the same pattern were fabricated for comparison of temperature characteristics. Optimum size and aspect ratio of rectangular sensor diaphragm were calculated by FEM. For polsilicon pressure sensor, polysilicon resistors of Wheatstone bridge were deposited by LPCVD to be used in a wide' temperature range. Polysilicon pressure sensors showed more stable temperature characteristics than single-crysta1 silicon in the range of $-20\sim125[^{\circ}C]$. To get low TCO (Temperature Coefficient of Offset), below $\pm$3 [${\mu}V/V/^{\circ}C$], it is needed for each TCR of piezoresistors to have a deviation within $\pm25[ppm/^{\circ}C]$ less than $\pm500[ppm/^{\circ}C]$ of resistors for polysilicon pressure sensor can result in low TCS(Temperature Coefficient of Sensitivity) of -0.1[%FS/$^{\circ}C$].

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.393-398
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• 1999

The temperature dependence of the viscosity was determined for an electrorheological(ER) fluid consisting of 35 weight% zeolite particles in hydraulic oil 46cSt. Thermal activation analysis were performed by changing the ER fluid's temperature from -1$0^{\circ}C$ to 5$0^{\circ}C$ at fixed electric field. According to the analysis, the activation energy for flow was about 79.64kJ/mole at E=0kV/mm. Generally, the hydraulic oil 46cSt will be operated at the temperature of about 4$0^{\circ}C$, the ER fluid's electric field dependence of viscosities were investigated at this temperature. also, the influence of adding the dispersant(Carbopl 940) on electrorheological effect of the ER fluid was discussed.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.387-389
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• 2009

PV module is manufactured by several steps such as cell sort, tabbing & string, lay-up, lamination processes. In oder to manufacture PV module, solar cell must be placed in high temperature. Soldering Process in high temperature is important because it directly influences electric output performance changes of solar cell in solar cell module. We consider applying momentary high temperature, while soldering solar cell, and expect change electric characteristics of PV module. In this paper, we measure electric output characteristics of solar cells after those are applied with high temperature changes for two seconds. From these results, we confirm with application of high temperature, $I_{sc}$ increase and $V_{oc}$ slightly decreases.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.96-101
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• 2001

This paper shows the temperature characteristics of a high speed angular contact ball gearing which is 7004C type with ISO P2 tolerance class. A built-in motor type high speed spindle which adopts an oil-air lubrication system was used to measure the temperature rise up to 60,000rpm. The gearing temperature was measured using thermocouples that were attached to the outside surfaces of the outer rings. The result showed that the continuous test method which was suggested in this paper is more effective than on and off method and the lubrication oil supply rate should be reduced in high speed rolling bearings as long as the seizure does not occur. And the result were confirmed that the bearings packed with ceramic balls are superior to those with steel balls in temperature characteristics.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.11
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• pp.566-571
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• 2004

Pulse modulation technique provide additional controling method for electron temperature and density in rf and microwave processing plasma. Transient characteristics of electron density and temperature have been measured in pulse modulated rf inductively coupled argon plasma using simple probe circuit. Electron temperature relaxation is clearly identified in the after glow stage. Controllability of average electron temperature and density depends on the modulation frequency and duty ratio. Numerical calculation of time-dependent electron density and temperature have been performed based on the global model. It has been shown that simple langmuir probe measurement method used for continuous plasma is also applicable to time-dependent measurement of pulse modulated plasma.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.87-91
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• 1998

In this paper, We analyzed the current-voltage characteristics with n-type silicon substrates concentration and temperature variations (Room temperature, 50$^{\circ}C$, 75$^{\circ}C$) in platinum silicide and silicon junction. The electrical parameters of measurement are turn-on voltage, saturation current, ideality factor, barrier height, dynamic resistance in forward bias and reverse breakdown voltage according to variations of junction concentration of substrates and measurement temperature variations. As a result, the forward turn-on voltage, reverse breakdown voltage, barrier height and dynamic resistance were decreased but saturation currents and ideality factor were increased by substrates increased concentration variations in platinum silicide and n-silicon junction. In increased measurement temperature (RT, 50$^{\circ}C$, 75$^{\circ}C$), the extracted electrical parameter values of characteristics were rises by increased temperature variations according to the forward and reverse bias.

• Journal of the Korea Institute of Military Science and Technology
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• v.8 no.2 s.21
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• pp.77-87
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• 2005

The thermomechanical characteristics were evaluated for 17-4PH stainless steel widely used in supersonic airframe subjected to both aerodynamic loading and heating. The thermomechanical tests were conducted under both elevated temperature and rapid heating condition from $1^{\circ}C/sec\;to\;28^{\circ}C/sec$. The thermomechanical behaviors under rapid heating were compared with those of elevated temperature after 1/2 hour exposure in terms of yield stress to investigate the influence of heating rates. A heating rate-yield temperature parameter was suggested for rapid heating based on time-temperature parameters, and master yield stress curve was obtained by using these parameters. The experimental results and methodology from this study can be used as basic engineering data when designing supersonic vehicle structures subjected to aerodynamic loading and severe heating environment.