• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2011.11a
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• pp.35-35
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• 2011

• Asian Journal of Atmospheric Environment
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• v.9 no.3
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• pp.214-221
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• 2015

This study considers mean skin temperature to calculate expected temperature using the new heat balance model because the skin temperature is the most important element affecting the heat balance outdoors. For this, we measured the skin temperature in high temperature condition of Korea and applied it to calculate the expected temperature. The calculated expected temperature is compared with the result calculated using previous models which use the estimated mean skin temperature by considering metabolic rate only. Results show that the expected temperatures are higher when measured mean skin temperature is applied to the model, compared to the expected temperature calculated by applying mean skin temperature data calculated using metabolic rate like previous models. The observed mean skin temperature was more suitable for outside conditions and expected temperature is underestimated when mean skin temperature calculated by the equation using metabolic rate is used. The model proposed in this study has a few limitations yet, but it can be applied in various ways to facilitate practical responses to extreme heat.

• Elastomers and Composites
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• v.32 no.5
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• pp.309-317
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• 1997

Estimation of the dielectric properties of insulating silicone rubbers added reinforcing fillers $(SiO_2,\;0{\sim}140phr)$ are very important to investigate the polymer structure. The characteristies of the dielectric absorption in insulating silicone rubbers were studied in the frequency range from 30Hz to 1MHz at the temperature range from $0{\sim}170^{\circ}C$. In the case of non-filled specimen, the dielectric loss is due to the syloxane which is the main chain of silicone rubber at the low temperature below $50^{\circ}C$ and the frequency at 330Hz, and is due to methyl and vinyl radical over the frequency of 1MHz. It is confirmed that the methyl radical or the vinyl radical becomes thermal oxidation at the high temperature over $100^{\circ}C$ and then the dielectric disperssing owing to the carboxyl radical Is appeared. In the case of filled specimen, the dielectric constant is in creased with the additives of reinforcing fillers due to the effect of interfacial polarization explained by MWS(Maxwell-Wagner-Sillars)'s law. The dielectric loss is decreased by the disturbance of reinforcing fillers that is permeated between networks.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.3
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• pp.82-89
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• 2012

The temperature of cryogenic propellant in the propellant tank increases during flight due to heat input from surroundings. The propellant which temperature rises up over the required condition of turbo-pump remains as unusable propellant at the end of flight. In this paper the estimation method of the heat transfer coefficient at the upper layer of cryogenic propellant was presented. The heat transfer mode at the propellant upper layer was considered as conduction. Temperature distributions near propellant surface obtained from heat transfer coefficient were compared with test data to show the possibility of this method.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.576-585
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• 2017

Dynamic thermal rating (DTR) of overhead transmission lines can provide a significant increase in transmission capacity compared to the static thermal rating. However, the DTR are usually estimated by the traditional thermal model of overhead conductor that is highly dependent on the solar, wind speed and wind direction data. Consequently, the estimated DTR would be unreliable and the safety of transmission lines would be reduced when the solar and wind sensors are out of function. To address this issue, this study proposed a novel thermal model of overhead conductor based on the thermal-electric analogy theory and Markov chain. Using this thermal model, the random variation of conductor temperature can be simulated with any specific current level and ambient temperature, even if the solar and wind sensors are out of function or uninstalled. On this basis, an estimation method was proposed to determine the DTR in the form of probability. The laboratory experiments prove that the proposed method can estimate the DTR reliably without measured solar and wind data.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.4
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• pp.121-127
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• 2012

This paper is to present the strength estimation of the cement mortar incorporating 20% of fly ash by equivalent age method. ASTM C 1074 was applied to achieve apparent activation energy($E_a$). Cement mortar was cured at the temperature of $5^{\circ}C$, $20^{\circ}C$ and $35^{\circ}C$ respectively to measure the setting time and compressive strength at designed age. According to test results, it is found that an increase in curing temperature resulted in an acceleration of setting time. $E_a$ was achieved to 34.75 KJ/mol. It was also found that by estimating strength development with Plowman and Gompertz model, good agreement between calculated value and measured one was achieved.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.6
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• pp.802-808
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• 2011

One of the important mechanical properties of cryogenic temperature structure material is fracture toughness. Research on normalization of fracture toughness test method is becoming very important issue with development of cryogenic structural elements. Specially, mechanical properties estimation by each micro-structure of welding department is important because it can cause unstable fracture when use under cryogenic environment in case of welding department. In this study, fracture toughness estimation test was carried out to unloading compliance method and sensitization heat-tread minimized test specimen at liquid nitrogen (77K), liquid helium (4K), 293K temperature to STS-316L base metal and weld metal.

• Ocean and Polar Research
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• v.36 no.1
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• pp.77-85
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• 2014

The quality control of ocean observations data is becoming a major issue as real-time observational data and information services have increased recently. Therefore, it is necessary for oceanographic instruments to calibrate. In this paper, we first introduce the CTD calibration system and traceability. Next, CTD calibration procedures and estimation of uncertainty of measurement are described. The expanded uncertainty (k = 2) of the temperature, pressure and conductivity are 0.$0.003^{\circ}C$, $6.0{\times}10^{-5}$ and 0.006 mS/cm respectively. Finally, the excellence of CTD calibration and its measurement capability has been proven by comparing the inter-calibration result of KIOST and Sea-Bird Electronics (SBE). CTD calibration residuals are less than ${\pm}0.0001^{\circ}C$, ${\pm}0.001$ MPa, ${\pm}0.0001$ S/m for SBE 3plus temperature sensor, SBE 19plus pressure sensor and SBE 4C conductivity sensor respectively.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.709-716
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• 2011

The temperature of cryogenic propellant in the propellant tank increases during flight due to heat input from surroundings. The propellant which temperature rises up over the required condition of turbo-pump remains as unusable propellant at the end of flight. In this paper the estimation method of the heat transfer coefficient at the upper layer of cryogenic propellant was presented. The heat transfer mode at the propellant upper layer was considered as conduction. Temperature distributions near propellant surface obtained from heat transfer coefficient were compared with test data to show the possibility of this method.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.5
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• pp.585-595
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• 2007

Representative impacts and effectiveness of surface meteorological observation data assimilation were examined in order to use wind resources estimation around southern coastal area of the Korean Peninsula. The data used in study are observational wind and temperature data at 5 and 41 sites of Regional Meteorological Offices and Automatical Weather Systems, respectively. Observation wind speed data tends to show small effective radius with limited area. Especially assimilation impacts of data observed at peninsula type sites like Yeosu play only around the inside of the peninsula. This limited effective radius for wind speed is caused by the strong correlation between topography and wind speed. And the efficient radius for surface air temperature is larger than that of wind. Data assimilation for observational air temperature is useful to increase the accuracy of wind energy estimation. However assimilation of wind data requires special care in its application due to high sensitivity of topographical complexity.