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        검색결과 34

        1.
        2022.10 구독 인증기관·개인회원 무료
        Viscosity is a fundamental physical property that is important in any system in which fluid movement occurs. In addition, most of the elements exist as ions in molten state in high-temperature molten salt, and electrical conductivity in such molten state is closely related to viscosity as a transport property. Molten salt reactor (MSR) and pyroprocess are representative processes dealing with high-temperature molten salts, actinide elements, and other radioactive materials. In MSR and pyroprocesses, the viscosity data must be provided as one of the fundamental physical property data required for safe process operations and countermeasures to severe accidents. In order to measure the viscosity of highly corrosive molten salt at high temperatures, we have built a in-house developed molten salt viscosity measurement system based on the Brookfield rotationary viscometer. We also developed a special correction technique to improve the accuracy of the viscosity measurement. In this study, the viscosity was measured at 500°C for NaCl-MgCl2 molten salt, which is selected as the base salt material of MSR system under development in Korea Atomic Energy Research Institute (KAERI), using our viscosity measurement system installed in a oxygen- and moisture-free Ar-atmosphere glovebox. Our viscosity measurement system was calibrated using a LiCl-KCl eutectic mixture with well-known viscosity value, and viscosity values obtained using our own correction methodology were compared with those of other conventional correction methods. In our further study, we plan to measure the NaCl-MgCl2-UCl3 system at various compositions and temperatures.
        2.
        2022.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Research is being actively conducted on the continuous thin plate casting method, which is used to manufacture magnesium alloy plate for plastic processing. This study applied a heat transfer solidification analysis method to the melt drag process. The heat transfer coefficient between the molten magnesium alloy metal and the roll in the thin plate manufacturing process using the melt drag method has not been clearly established until now, and the results were used to determine the temperature change. The estimated heat transfer coefficient for a roll speed of 30 m/min was 1.33 × 105 W/m2·K, which was very large compared to the heat transfer coefficient used in the solidification analysis of general aluminum castings. The heat transfer coefficient between the molten metal and the roll estimated in the range of the roll speed of 5 to 90 m/min was 1.42 × 105 to 8.95 × 104 W/m2·K. The cooling rate was calculated using a method based on the results of deriving the temperature change of the molten metal and the roll, using the estimated heat transfer coefficient. The DAS was estimated from the relationship between the cooling rate and DAS, and compared with the experimental value. When the magnesium alloy is manufactured by the melt drag method, the cooling rate of the thin plate is in the range of about 1.4 × 103 to 1.0 × 104 K/s.
        4,000원
        3.
        2022.05 구독 인증기관·개인회원 무료
        Measurement of the physical properties of high-temperature molten salts is important for the efficient design and operation of molten salt reactors (MSR) in which the reactor coolant and nuclear fuel are in a homogeneous liquid state. Although some crucial physical properties such as viscosity, thermal conductivity, density, etc., have been drawing much attention, relative data, especially for molten chloride salts, are scarce. Thus, it is urgent to prepare the viscosity data as one of the key transport properties in thermal hydraulics analysis. However, it is not an easy task to measure the molten salt viscosity with high accuracy due to end effect, a small gap between the chamber and spindle, thermal expansion of the chamber and spindle at high temperatures in a rotational viscometer. Additionally, molten salt temperatures inside furnace are not uniform due to the large temperature gradient inside the chamber, and therefore the assumption of laminar condition can be violated. In this study, geometric factors, which can be a major interference in the torque measurement, were considered for the accurate determination of the viscosity. We established a high-temperature molten salt viscosity measurement system with Brookfield rotational viscometer. KNO3 molten salt was used as a model substance at a temperature range of 650–773 K. In-house designed spindles and chambers were made of corrosion-resistant alumina. Thermal expansion has a significant influence on the size and shape of the chamber and spindle. The effect of thermal expansion on the conventional correction method was examined with temperature variation and distribution. Gap size variation was also investigated in order to improve the accuracy.
        7.
        2019.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was designed to examine the performance of an aspirated radiation shield(ARS), which was made at the investigator's lab and characterized by relatively easier making and lower costs based on survey data and reports on errors in its measurements of temperature and relative humidity. The findings were summarized as follows: the ARS and the Jinju weather station made measurements and recorded the range of maximum, average, and minimum temperature at 2.0~34.1oC, -6.1~22.2oC, –14.0~15.1oC and 0.4~31.5oC, -5.8~22.0oC, -14.1~16.3oC, respectively. There were no big differences in temperature measurements between the two institutions except that the lowest and highest point of maximum temperature was higher on the campus by 1.6oC and 2.6oC, respectively. The measurements of ARS were tested against those of a standard thermometer. The results show that the temperature measured by ARS was lower by –2.0oC or higher by 1.8oC than the temperature measured by a standard thermometer. The analysis results of its correlations with a standard thermometer reveal that the coefficient of determination was 0.99. Temperature was compared between fans and no fans, and the results show that maximum, average, and minimum temperature was higher overall with no fans by 0.5~7.6oC, 0.3~4.6oC and 0.5~3.9oC, respectively. The daily average relative humidity measurements were compared between ARS and the weather station of Jinju, and the results show that the measurements of ARS were a little bit higher than those of the Jinju weather station. The measurements on June 27, July 26 and 29, and August 20 were relatively higher by 5.7%, 5.2%, 9.1%, and 5.8%, respectively, but differences in the monthly average between the two institutions were trivial at 2.0~3.0%. Relative humidity was in the range of –3.98~+7.78% overall based on measurements with ARS and Assman's psychometer. The study analyzed correlations in relative humidity between the measurements of the Jinju weather station and those of Assman's psychometer and found high correlations between them with the coefficient of determination at 0.94 and 0.97, respectively.
        4,000원
        10.
        2018.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study aims to evaluate thermal performance using the ASTR method. Its findings are as follows: 1) The measured U-Values of 49A type and 59A type walls were almost the same as the theoretically calculated values. 2) One notable phenomenon for both walls was that the interior surface temperatures of the channels attached to corners were up to 10.4% lower than that of the cross of the wall, even though they consisted of the same materials. This is due to the surface temperature drop caused by the thermal bridge. 3) The surface temperatures of the thermal bridge were converted into U-Values. The U-Value of the top left corner on the 59A type house was 1.044W/m²K, and of the bottom right corner on the 49A type house was 0.959W/m²K. Therefore, the thermal performance of the thermal bridge area was decreased after construction. 4) Differences were found in the results of comparing heat transfer analysis simulation data and measured data. A maximum difference of 12.4% occurred in the top left corner on 59A type, and of 7.6% occurred in the bottom right corner on 49A type. 5) The results of a heat transfer analysis simulation showed that the temperature of both 49A type and 59A type top right corner were the lowest, but in-situ measurement results were the lowest in the bottom right corner on 49A type and in the top left corner on 59A type. These results are considered to be due to the occurrence of thermal bridges and a deterioration in the construction quality.
        4,000원
        11.
        2018.05 구독 인증기관·개인회원 무료
        Tunnel is the main infrastructure in transportation system especially in Gangwon province which has 90% of its area covered by mountains. Responding to the needs for evaluating the tunnel damage in this region, the temperature inside 10 tunnels, one-way and two-way, were measured in winter by using temperature sensors. The temperatures along the length of tunnel, from the entrance until the exit, were obtained from sensors placed at 2 meters above the road. The measurement results showed the distribution of the temperature along the length of the tunnels since November 2016 until March 2017. The data showed that among all the one-way tunnels, the variation of the temperature at all positions along the length of the tunnels have almost the same gradient of temperature of all months observed. There were no significant changes between the temperatures at those points along the tunnel; whereas the changes at the entrances and the exits of the tunnels were remarkable. It was also noticed that there was the different trend of temperature variation between the one-way and two-way tunnels.
        12.
        2016.05 구독 인증기관 무료, 개인회원 유료
        The measuring equipment capable of thermo measuring of wide range thermo range(0℃ ~ 160 0℃) will be developed in a high temperature and high pressure state. The developed technology is a combination of one measuring two different temperatures measured in the measuring to a high temperature as possible at a low temperature from thermocouple module(thermocouple) to develop an integrated measuring device capable of measuring the broadband. Also, to develop two or more guard module to ensure the water-tightness and durability of the device to develop in a vacuum or high pressure is applied to the one-piece measuring device.
        4,000원
        13.
        2016.05 구독 인증기관 무료, 개인회원 유료
        Infrared thermography provides the colorful images of concerning area where local changes of surface temperature occurs and can be used to measure the fine temperature of human body. Unlike the radiography technique, it is determined by the presence or absence of existing anatomical principles capable of quantitative evaluation and visible to the physiological and functional state of the human body. In this paper, it was studied the characteristics of dynamic motion conditions in the hands due to physiological changes of temperature distribution. The results showed that the difference between the change in temperature characteristics for the left and right hand.
        3,000원
        14.
        2014.07 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Solar cells exhibit different power outputs in different climates. In this study, the temperature dependence of open-circuit voltage(V-oc), short-circuit current(I-sc), fill factor(FF) and the efficiency of screen-printed single-crystal silicon solar cells were studied. One group was fabricated with homogeneously-doped emitters and another group was fabricated with selectively-doped emitters. While varying the temperature (25, 40, 60 and 80˚C), the current-voltage characteristics of the cells were measured and the leakage currents extracted from the current-voltage curve. As the temperature increased, both the homogeneously-doped and selectively-doped emitters showed a slight increase in I-sc and a rapid degradation of V-oc. The FF and efficiency also decreased as temperature increased in both groups. The temperature coefficient for each factor was calculated. From the current-voltage curve, we found that the main cause of V-oc degradation was an increase in the intrinsic carrier concentration. The temperature coefficients of the two groups were compared, leading to the idea that structural effects could also affect the temperature dependence of current-voltage characteristics.
        4,000원
        15.
        2014.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The dissertation is on the measurement of the strain caused by the characteristics and the temperature changes of the TIG welded zone which is used with 3D ESPI system that is functionally modified through the laser ESPI system. Experimental results have derived from the fact that the welded zone has micro crack during the various phased of the process such as rolling, alkali cleaning, air cooling and heat processing due to the repetitious up-and-down of the temperature. Especially, both 60℃ and 90℃ are selected to measure the strain on the welded zone which can be effected by these two temperatures in the manufacturing process. The flat plate differences between ESPI and the strain gage are within 2 %, and they are the exactly same with the results from the temperature changes of 60 ℃ and 90 ℃, and also within 3 % and 4 %. As the tensile load increase, the strain of aluminum material increases linearly. Also the same effect are observed as the temperature goes up with irregular-line type. The comparison of the strain by ESPI and the strain gage in the welded specimen is within the 2.6% when it is under the room temperature and low-load conditions, while it is measured within 3 % under the high load condition.
        4,000원
        16.
        2013.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Local Nusselt number and temperature field distribution within the compound duct with gap have been measured. Measurement of air and wall temperature span a range of gap width from 2mm to 6mm. Also, the Reynolds number is variated from 20,000 to 40,0000. In order to observe the correlations between gap width and turbulent heat transfer, the present measurement has tried to verify the enhancement effect of heat transfer when a gap exists within the compound channel. From this measurement, we could see that the pulsating flow has generated a strong turbulent flow mixing within the compound channel. And the turbulent flow mixing in the pulsating flow plays an effective role of enhancing the Nusselt number by making the fluid temperature uniformly within the compound channel.
        4,000원
        17.
        2011.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 시험은 버섯 배지를 살균할 때 배지의 내부에 삽입하여 실시간으로 온도 측정값을 저장할 수 있고 고온고압에 견디는 기기(iButton Temperature Data Logger DS-1922T)를 사용하였다. 이 온도측정기는 살균기의 종류, 배지의 종류와 용량, 살균방법별로 일정한 시간 간격에 따라 살균기 및 배지 내부의 온도변화와 살균온도 유지시간의 측정이 가능하였다. 이 실험에 사용한 방법과 결과는 버섯 재배현장에서 응용함으로써 알맞은 배지 살균으로 버섯의 안정생산에 기여할 것으로 기대된다.
        4,000원
        18.
        2010.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Over the years, scientists have developed many test methods to evaluate the efficacy of skin care products. The needs for objective assessment have stimulated to develop instruments that are capable of reliably monitoring some parameters in evaluating skin conditions. The beauty is evaluated as a measure of smoothness of skin surface. Quantitative size measurements of skin pores is also important concept to evaluate the their conditions. The purpose of this paper is to measure the temperature change of skin and the size of pores in the skin. The pore sizes were changed by its varying skin temperature. They were decreased by applying a essence which is contained with propellant and contents.
        4,000원
        20.
        2006.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        High temperature dielectric constants of the various ceramic materials have been measured using cavity perturbation method. The measurements were applied to refractory, traditional and fine ceramic powder compacts from room temperature to . Calibration constant in the equation suggested by Hutcheon et al., was determined from the dielectric constants of reference specimen (teflon and alumina) at room temperature. From these results, informations on the refectory materials were obtained for the microwave kiln design and understanding of the microwave heating effects of ceramics have been improved.
        4,000원
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