• Solar Energy
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• v.12 no.2
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• pp.1-8
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• 1992

Identifying characteristics of heating and cooling systems requires estimation of thermal load of specific time interval, especially in cases that its system is operated intermittently, by using thermal storage, of in a partial load condition. Estimating the thermal load, however, needs to forecast hourly weather data variation. Hence, this paper attempts to examine characteristics of hourly ourdoor temperature variation as a preliminary research for the mathematical modeling of the hourly weather variation. Speculating characteristics of daily minimum and maximum temperature occurances, hourly outdoor temperature variation, and daily temperature differences in the increasing range ($07h{\sim}15h$) and decreasing range($15h{\sim}07h$), we were able to analyze changing patterns of daily temperature differences in each range in terms of daily solar amount, cloud ratio, and other weather data. Results from the multiple regression analysis enables us to conclude that daily differences in the increasing range are strongly affected last night temperature itself while the other range's differences are influenced by many weather data, which are solar amount, the variation of cloud, and the maximum temperature of the previous day.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.3
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• pp.409-424
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• 1987

Simulation on the hot water ONDOL heating system was made in order to investigate the variation of room temperature and specific fuel consumption of boiler. Heat balance equation was derived by response factors and solved implicitly. Variation of room temperature and specific fuel consumption of boiler were calculated with respect to the thickness of room floor, the absorptivity of wall for solar radiation, on-off temperature range of boiler and air exchange. The results show that specific fuel consumption of boiler is independent of the thickness of room floor and decreases with increasing the absorptivity of wall and on-off temperature range of boiler. However, it increases with increasing the air exchange. They also show that, when the absorptivity and on-off temperature range of boiler are increased, the amplitudes of room temperature variation increase.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.186-187
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• 2007

In this work, a temperature stable PWM(Pulse width modulation) circuit is proposed. The designed PWM circuit has a temperature dependent current source and a temperature independent voltage to compensate electrical characteristics with operating temperature. The variation of driving current is from about 4% to -6% in the temperature range $0^{\circ}C\;to\;70^{\circ}C$ compared to the current at the room temperature. The variation of bandgap voltage reference is from about 1.3% to -0.2% with temperature when the supply voltage is 3.3 volts. From simulation results, the variation of output pulse width is less than from 0.86% to -0.38% in the temperature range $0^{\circ}C\;to\;70^{\circ}C$.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.8
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• pp.831-838
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• 2013

This paper focused on the design of an efficient temperature controller for a plant with a wide range of operating temperatures. The greater the temperature difference a plant has, the larger the nonlinearity it is exposed to in terms of heat transfer. For this reason, we divided the temperature range into five sections, and each was modeled using ARMAX(auto regressive moving average exogenous). The movement of the dominant poles of the sliced system was analyzed and, based on the variation in the system parameters with temperature, optimal control parameters were obtained through simulation and experiments. From the configurations for each section of the temperature range, a temperature-based gain-scheduled controller (TBGSC) was designed for parameter variation of the plant. Experiments showed that the TBGSC resulted in improved performance compared with an existing proportional integral derivative (PID) controller.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.105-110
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• 2006

The most sensitive part of the installed optical cable is the optical loss variation of the splicing point according to the environmental changes. This paper presents the details of the experimental results of the external environmental changes on optical loss, such as bending, temperature variation, temperature variation after water osmosis and variation. Through the bending test of optical fiber, rapid increase of optical loss was measured within the diameter of 30mm. The result of optical loss variation within the temperature range of $-30^{\circ}C{\sim}60^{\circ}C$ is less than 0.02dB. It was confirmed that the maximum optical loss increased up to 0.2dB in case of water osmosis within the temperature range of $-40^{\circ}C{\sim}80^{\circ}C$. There is small optical loss variation of 0.01dB under the 1mm vibration test. The experimental results of this paper can be used as the reference data for the design of the optical fiber cable splicing enclosure to protect the optical loss variation due to environmental changes.

• Smart Structures and Systems
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• v.19 no.2
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• pp.137-149
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• 2017

Under the interference of the temperature effect, the alternation of cable force due to damages of a cable-stayed bridge could be difficult to distinguish. Considering the convenience and applicability in engineering practice, simple air or cable temperature measurements are adopted in the current study for the exclusion of temperature effect from the variation of cable force. Using the data collected from Ai-Lan Bridge located in central Taiwan, this work applies the ensemble empirical mode decomposition to process the time histories of cable force, air temperature, and cable temperature. It is evidently observed that the cable force and both types of temperature can all be categorized as the daily variation, long-term variation, and high-frequency noise in the order of decreasing weight. Moreover, the correlation analysis conducted for the decomposed variations of all these three quantities undoubtedly indicates that the daily and long-term variations with different time shifts have to be distinguished for accurately evaluating the temperature effect on the variation of cable force. Finally, consistent results in reducing the range of cable force variation after the elimination of temperature effect confirm the validity and stability of the developed method.

• Journal of the Korean Ceramic Society
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• v.16 no.3
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• pp.142-154
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• 1979

The effects of microstructures and some additives $(CoO and Al_2O_3$) on the magnetic properties such as initial permeability, $\mu$-T curve, coercive force, and magnetic induction of MnZn ferrites have been studied. The powder was prepared by Hot Petroleum Drying Method. The basic composition of MnZn ferrites was 25.5mole % MnO, 22.0 mole% ZnO, 52.5 mole% $Fe_2O_3$. CoO in a concentration range from 0.05 to 0.5 mole% and $Al_2O_3$ from 2.5 to 7.5 mole% were added. Sintered density increased up to 97.5% of theoretical density. Permeability increased as average grain size increased, and that coercive force decreased as average grian size increased. Magnetic induction increased as sintered density increased. The variation of initial permeability with temperature in a temperature range from 0$^{\circ}$ to $60^{\circ}C$ was lowered (a flatter $\mu-T$ curve) as sintering temperature decreased. The compensation temperature To ofmagnetocrystalline anisotropy constant K1 and initial permeability varied with the species and amount of additives. When 0.05 mole% CoO was added to the basic composition, initial permeability at $15^{\circ}C$ increased from 5200 to 5900. The variation ofinitial permeability with temperature in a temperature range from 0^{\circ}to $60^{\circ}C$ was smaller (a flatter $\mu$-T curve) than that of the basic composition of Mn Zn ferrites. When 2.5 mole% $Al_2O_3$ was added, initial permeability at $15^{\circ}C$ decreased from 5200 to 3000. But the variation of initial permeability with temperature in a temperature range from 0$^{\circ}$to $60^{\circ}C$ was smaller (a flat ter $\mu-T$ curve) than when 0.05 mole% CoO was added. Experimental results showed that the conditions necessary for the occurrence of a very high permeability and a flat $\mu$-T curve were controversial even in a temperature range from $0^{\circ}$to $60^{\circ}C$.

• Journal of Advanced Information Technology and Convergence
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• v.8 no.2
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• pp.59-67
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• 2018

The minimum power supply voltage of a typical bandgap current reference (BGCR) is limited by operating temperature and input common mode range (ICMR) of a feedback amplifier. A new BGCR using a bandgap voltage generator (BGVG) is proposed to minimize the effect of temperature, supply voltage, and process variation. The BGVG is designed with proportional to absolute temperature (PTAT) characteristic, and a feedback amplifier is designed with weak-inversion transistors for low voltage operation. It is verified with a $0.18-{\mu}m$ CMOS process with five corners for MOS transistors and three corners for BJTs. The proposed circuit is superior to other reported current references under temperature variation from $-40^{\circ}C$ to $120^{\circ}C$ and power supply variation from 1.2 V to 1.8 V. The total power consumption is $126{\mu}W$ under the conditions that the power supply voltage is 1.2 V, the output current is $10{\mu}A$, and the operating temperature is $20^{\circ}C$.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.6
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• pp.514-519
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• 2012

Abalone culture is one of important coastal fisheries off Wando in the southeast coast of Korea. Since cage culture for abalones was popularized, Understanding of temperature variation, which is important to raise abalones and to prevent their mass mortalities, is necessary. We analyzed temperature data from 2005 to 2009 obtained at Sinji-do and Cheongsan-do off Wando. Sinji-do, which is relatively close to land, had yearly wide range of temperature and rate of temperature variation. It is likely to be caused by heating of solar radiation in summer and cooling in winter at the shallow area. Rate of temperature variation in autumn was higher than that in spring. In summer short term variation of temperature corresponding tidal period was distinguished clearly. Diurnal temperature range, abrupt temperature change, was larger open sea. Comparison between temperatures of two stations and favorable raising conditions of abalones showed that Cheongsan-do, located out to sea, appears to be more appropriate than Sinji-do.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.193-196
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• 2000

In this work, I propose a temperature stable voltage-to-frequency converter in which the output frequency is directly proportional to the input voltage. The output frequency range is from 20㎑ to 60㎑ and the difference between simulated and calculated values is less than about 5％ for this range of output frequency. The temperature variation of sample output frequencies is less than ${\pm}$0.5％ in the temperature range -25$^{\circ}C$ to 75$^{\circ}C$.