• 한국과학교육학회지
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• 제10권1호
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• pp.95-118
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• 1990

This students ideas in science are diverse and unique It is realized that children's preconceptions and misconceptions established before lessoning hgve a crucial in fluence on the following education. so it is meaningful to analyse the children's concept of temperature for the better teaching strategy in this study. This survey of the Elementary school children's concept is designed for the subtopics of temperature as the relation between heat and temperature, He relation between volume(size) and temperature, the temperature of change of state on water, the temperature of substances in the condition of thermal equilibrium. Using Clinical method, this research was executed to 306 children at elementary school. The network method or the analyse of questionnaires were used to analyse the children's response. Findings of this survey are as follow. Students are already familiar with such concept as this increase of temperature by geating, but they think every substance is not the case. Many students appears to believe that the temperature of an object(substance) is related to its size(vloume) Qualitative tasks are difficult than qualitative ones. This trend appear highly in the low grade students. Don't know the temperature of change of state on water and it's stability They think that the temperature is determined by the heating time(period) and the temperature of heating source. Students think, in general that temperature of substance in the condition of thermal equilibrium is different.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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• pp.22-24
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• 2004

The land use has changed rapidly since 1960s in accordance with urbanization in Seoul Metropolitan Region. As a result, the urban microclimate has undergone changes as well. This study aims to recognize trend of the urban heat island change which is caused by land use change during urbanization in large city. Thermal data of Landsat TM images in 1987 and 1999 were for land surface temperature change detection in the study.

• Journal of Advanced Marine Engineering and Technology
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• 제27권5호
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• pp.624-632
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• 2003

In the gasoline engine industry. there has been a trend towards the development of high performance engines with improved fuel efficiency, reduced weight and smaller sizes. These trends help to solved engine problems related to thermal load and abnormal combustion. In order to investigate these Problems, a thin film-type probe for instantaneously measuring temperatures has been suggested. A method for manufacturing such a probe was established in this study. The instantaneous surface temperature of a constant volume combustion chamber was measured by this probe and the heat flux was obtained through Fourier analysis. A peak instantaneous temperature was obtained after 55∼60 ms from ignition and the temperature increased according to an equivalence ratio and varied differently according to the position of the probe. Total heat loss during combustion period was affected by the equivalence ratio and differed widely in accordance to the position of the probe.

• 한국자동차공학회논문집
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• 제10권4호
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• pp.158-165
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• 2002

This Paper deals with the headlamp lens surface temperature distribution of p/c headlamp using the three categories of H4 halogen bulbs. Glass is gradually replaced by P/C for the lens material off vehicle headlamp due to the weight reduction and stream lined body of a vehicle. With this trend, the newly established standards for a headlamp with a P/C lens in Europe requires that the heat generated by a bulb should not distort the lens surface. Also the requirements fur the bulb of a headlamp are being enforced in U.S.A & Europe. However, such requirements are not established yet in Korea. By using three kinds (60/55w, 100/90w, 130/90w) of H4 halogen bulbs in this experiment, the surface temperature distribution and Max. temperature on the lens were measured. The results of this study implies the necessity of requirement fur the bulb off headlamp.

• 설비공학논문집
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• 제13권7호
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• pp.564-571
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• 2001

The present study investigated the effect of key parameters on the performance of a cascade system using R-22 and R-23 refrigerants. Experimental data for the cascade system have been compared with simulation results using thermodynamic analysis. The cascade system tested at the evaporating temperature of $-80^{\circ}C $ and the condensing temperature of$40^{\circ}C $. The key experimental parameters were the evaporating temperature of the HTC(-35, -30, -25, -20, $-15^{\circ}C $) and mass flux of the HTC(200, 250, 300kg/$m^2$s). As the evaporating temperature and the mass flux of the HTC were increased respectively, the COP and the refrigerating efficiency were increased and then decreased while the volume flow rate per unit refrigeration capacity showed the opposite trend. The maximum COP and refrigerating efficiency were obtained at the evaporating temperature of the HTC of $-25^{\circ}C $ and the mass flux of 250 kg/$m^2$s.

• Applied Microscopy
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• 제45권2호
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• pp.89-94
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• 2015

This article briefly reviews the results of recently reported research on high-temperature Pb-free solder alloys and the research trend for characterization of the interfacial reaction layer. To improve the product reliability of high-temperature Pb-free solder alloys, thorough research is necessary not only to enhance the alloy properties but also to characterize and understand the interfacial reaction occurring during and after the bonding process. Transmission electron microscopy analysis is expected to play an important role in the development of high-temperature solders by providing accurate and reliable data with a high spatial resolution and facilitating understanding of the interfacial reaction at the solder joint.

• 한국재료학회지
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• 제25권12호
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• pp.678-682
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• 2015

The electrical property of polymer matrix composites with added carbon powder is studied based on the temperature dependency of the conduction mechanism. The temperature coefficient of the resistance of the polymer matrix composites below the percolation threshold (x) changed from negative to positive at 0.20 < x < 0.21; this trend decreased with increasing of the percolation threshold. The temperature dependence of the electrical property(resistivity) of the polymer matrix composites below the percolation threshold can be explained by using a tunneling conduction model that incorporates the effect of the thermal expansion of the polymer matrix composites into the tunneling gap. The temperature coefficient of the resistance of the polymer matrix composites above the percolation threshold has a positive value; its absolute value increased with increasing volume fraction of carbon powder. By assuming that the electrical conduction through the percolating paths is a thermally activated process and by incorporating the effect of thermal expansion into the volume fraction of the carbon power, the temperature dependency of the resistivity above the percolation threshold can be well explained without violating the universal law of conductivity.

• 한국환경과학회지
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• 제27권3호
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• pp.147-154
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• 2018

The purpose of this article is analyzing the impacts of seawater surface temperature rise on sea mustard yields of Goheung and Wando coast in Korea, with employing a panel data regression model. Our results show that there has been a negative impacts on sea mustard yields as seawater surface temperature continuously has been rising. Especially if the upward trend in seawater surface temperature since 2005 will be maintained in future, sea mustard yield is expected to decrease by 2.6% per year.

• 대기
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• 제16권1호
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• pp.49-53
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• 2006

The present study has examined interdecadal variations of the diurnal temperature range (DTR, daily maximum temperature minus daily minimum temperature) during the New Year season in Seoul for the period 1954-2005. Here, the average DTR for the New Year holidays (three consecutive days; one day before the New Year, the New Year day, and one day after the New Year) minus the average DTR for 14 days, 7 days before and 7 days after the New Year holidays, is defined for representing the New Year effect. The DTR index does not show notable trend until the late 1970s but shows obvious positive values afterward. For example, the difference of the average DTR between two periods (1980-2005 minus 1954-1979) is $0.65^{\circ}C$, which is meaningful at the 95% confidence level. This result demonstrates that intense human activity even for the limited period may provide climate impact in local regions. Its plausible causes are discussed.

• Nuclear Engineering and Technology
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• 제30권4호
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• pp.364-376
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• 1998

The statistical analysis method was applied to the evaluation of fracture toughness in the ductile-brittle transition temperature region. Because cleavage fracture in steel is of a statistical nature, fracture toughness data or values show a similar statistical trend. Using the three-parameter Weibull distribution, a fracture toughness vs. temperature curve (K-curve) was directly generated from a set of fracture toughness data at a selected temperature. Charpy V-notch impact energy was also used to obtain the K-curve by a $K_{IC}$ -CVN (Charpy V-notch energy) correlation. Furthermore, this method was applied to evaluate the neutron irradiation embrittlement of reactor pressure vessel (RPV) steel. Most of the fracture toughness data were within the 95% confidence limits. The prediction of a transition temperature shift by statistical analysis was compared with that from the experimental data.