• Journal of the Korean Society for Heat Treatment
• /
• v.4 no.3
• /
• pp.54-62
• /
• 1991

The effect of tempering temperature on the ultrasonic propagation velocity at SCM 440 steel quenched from $870^{\circ}C$ and $1000^{\circ}C$ has been studied by metallurgical and crystallographical observation. The measurements of ultrasonic velocity were made on the specimen by appling an immersion ultrasonic pulse-echo technique with a constant frequency of 10 MHz. The quenched microstructure of this steel was a lath martensite. As the tempering temperature was increased, the martensite was transformed into the tempered martensite composed of cementite and carbide. The ultrasonic velocity increased with increasing the tempering temperature. It was thought that these were resulted from the microstructural transformation. The change of ultrasonic propagation velocity with quenching and tempering heat treatment was resulted from microstrain due to the change of internal stress. Considering these results concerning to the change of ultrasonic propagation velocity. the phenomena of microstructural transformation were estimated. Consequently, it was thought that the degree of quenching and tempered heat treatment of steel could be nondestructively evaluated with the change of ultrasonic propagation velocity.

• Korean Journal of Materials Research
• /
• v.19 no.10
• /
• pp.533-537
• /
• 2009

This paper presents a new method for the improvement of color temperature without the change of the driving scheme using transparent dielectric layers with various metal oxides (CeO$_2$, Co$_3$O$_4$, CuO, Fe$_2$O$_3$, MnO$_2$, NiO) in plasma display panels (PDP). In this study, we fabricated ZnO-B$_2$O$_3$-SiO$_2$-Al$_2$O$_3$ glasse with various metal oxides and examined the optical properties of these glasses. As the metal oxides were added to the glasses, the visible transmittances of the dielectric layers decreased and the transmittances in special wavelength regions were reduced at different rates. The change of the transmittance in each wavelength range induced the variation of the visible emission spectra and the change of the color temperature in the PDP. The addition of Co$_3$O$_4$ and CuO slightly decreased the intensity of the blue light, but the intensities of the green and the red light were significantly decreased. Therefore, the color temperature can be improved from 6087K to 7378K and 7057K, respectively.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.20 no.2
• /
• pp.157-164
• /
• 2007

The prediction of the temperature distribution change of the spent nuclear fuel disposal canister and its surrounding structures (bentonite buffer, granitic rock etc.) due to the spent fuel heat is very important for the design of the 500m deep granitic repository for the spent nuclear fuel disposal canister (about 10,000 years long) deposition. In this study, the temperature distribution change of the composite structure which comprises the canister, the bentonite buffer, the deposition tunnel due to the spent fuel heat is computed using the numerical analysis method. Specially, the temperature distribution change of the composite structure is analysed as the deposition time elapses up to m years. The analysis result shows that the temperature of each part of the repository increases slowly in different way but the latest part temperature increases slowly up to 150 years and thereafter decreases slowly.

• Korean Journal of Bronchoesophagology
• /
• v.6 no.2
• /
• pp.152-158
• /
• 2000

Backgroud and Objectives： Because the pain is subjective in human, we frequently need the objective tool for estimation of pain. The Visual Analog Scale (VAS) is a method for pain grading, but it is also a subjective method. The purpose of this study is to seek an objective method for measurement of pain. Author suggests that the estimation of local body temperature may be associated with the severity of pain in tonsillar disease and the change of it measured by Digital Infrared Thermographic Imaging (DITI), may also be correlated with the change of pain. Materials and Method : Four groups were selected and measured for VAS and body temperature in DITI. Group A and B were post-tonsillectomy groups divided by age. Group C was acute tonsillitis group. Group D was peritonsillar abscess group. Results : In Group A and B, the subjective VAS was significantly correlated with objective local body temperature (correlation coefficient r=0.673, 0.647) and significant correlation was also present in acute tonsillitis and peritonsillar abscess groups(r=0.596,0.642). Conclusion : The change of pain was strongly associated with that of local body temperature in tonsillar disease. DITI is a useful method for objective grading of pain and can be used for the study of postoperatve pain and effectiveness of pain control.

• Journal of Energy Engineering
• /
• v.8 no.2
• /
• pp.224-232
• /
• 1999

Latent heat storage system using micro-encapsuled phase change material is effective method for floor heating of house and building. The temperature profile in capsule block and flow rate of hot water are important parameters for the development of heat storage system. In the present study, a mathematical model based on 3-D, non-steady state, Navier-Stokes equations, scalar conservation equations and turbulence model ($\kappa$-$\varepsilon$), is used to predict the temperature profiles in capsule and the velocity vectors in hot water pipe. The multi-block grids and fine grids embedding are used to join the circle in hot water pipe and square in capsule block. The phase change process of the capsule is quite complex not only because the size of phase change material is very small, but also because phase change material is mixed with the cement to form thermal storage block. In calculation, it's assumed that the phenomena of phase change is limited only the thermal properties of phase change material and the change of boundary is not happened in capsule. The purpose of this study is to calculate the temperature profiles in capsule block and velocity vectors in hot water pipe using the numerical calculation. Two kinds of thermal boundary condition were considered, the first (case 1) is the adiabatic condition for the both outside surfaces of the wall, the second (case 2) is the case in which one surface is natural convection with atmosphere and another surface is adaibatic. Calculation results are shown that the temperature profile in capsule block for case 1 is higher than that for case 2 due to less heat loss in adaibatic surface. Specially, in the domain of near Y=0, the difference of temperature is greater in case 1 than in case 2. The detailed experimental data of capsule block on the temperature profile and the thermal properties such as specific heat and coefficient of heat transfer with the various temperature are required to predict more exact phenomena of heat transfer.

• Journal of the Korean Society of Visualization
• /
• v.22 no.2
• /
• pp.104-114
• /
• 2024

To effectively control heat generation resulting from advancements in fast discharging technology for electric vehicle batteries, hybrid Battery Thermal Management Systems (BTMS) are gaining attention. In this study, a BTMS combining Phase Change Material (PCM) with Oscillating Heat Pipe (OHP) was designed. During the phase change process of the PCM, the maximum battery temperature increased slowly. Additionally, due to the excellent heat transfer capability of the OHP, the PCM/OHP BTMS delayed the time when the maximum battery temperature exceeded 50 ℃ by 810 s compared to the PCM/copper fin BTMS, resulting in the maximum battery temperature that was 41.29 ℃ lower at 3600 s. Furthermore, in the section where the latent heat of the PCM had the greatest impact, the slope of the battery temperature difference was 0.0017 lower than that of the PCM/copper fin BTMS. Therefore, the PCM/OHP BTMS demonstrates its potential as a viable hybrid BTMS.

• The Journal of Information Technology
• /
• v.9 no.3
• /
• pp.67-75
• /
• 2006

This study deals with the computing the temperature change of surface to the increment of time and diffusivity, the heat flux during irradiation of laser. In addition, the computer algorithm for computing the penetration change of the corresponding surface irradiated is developed. The result of this study shows the possibility to treatment of cancer, abnormal cell and biological tissue during irradiation of laser.

• Journal of Environmental Impact Assessment
• /
• v.22 no.1
• /
• pp.19-26
• /
• 2013

The propose of this study is to analyze the optimum spatial resolution of the urban spatial thermal environment structure and to evaluate of the possibility detection using aerial photographs and thermal satellite images. The proper techniques of the optimum spatial resolution for the urban spatial thermal environment structure were analyzed. Thermal infrared satellite image of Seoul city were used for the change rate of surface temperature variation and suggested to the spatial extent and effects of urban surface characteristics and spatial data was interpreted as regions. To extract the surface temperature, Landsat thermal infrared satellite image compared with an automatic weather station data and in the field of the measured temperature and surface temperature by thermal environment affects, the spatial domain has been verified. The surface temperature of the satellite images to extract after adjusting surface temperature isotherms were constructed. The changes in surface temperature from 2008 to 2012 the average surface temperature observation images of changing areas were divided into space. The results of this study are as follows: Through analysis of satellite imagery, Seoul city surface temperature change due to extraction comfort indices were classified into four grades. The comfort index indicative of the temperature of Gangnam-gu, $23.7{\sim}27.2(^{\circ}C)$ range and Songpagu, a $22.7{\sim}30.6(^{\circ}C)$ respectively, the surface temperature of Yeouido $25.8{\sim}32.6(^{\circ}C)$ were in the range.

• Journal of The Korean Association For Science Education
• /
• v.10 no.1
• /
• pp.95-118
• /
• 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.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.15 no.2
• /
• pp.127-136
• /
• 2012

Global climate change and urban heat island have been the main factors which changed leaf burst timing and leaf growth performance in urban forests. Therefore, the ecosystem in urban forests were modified and the types and composition of wildlives, living in the urban forests, were desperately changed due to the urban heat island. This study was done to identify phenological phenomena appeared in urban forests due to the urban climate change by comparing the morphological changes of leaves due to the change of temperature in Spring. The study focused on nine urban forests distributed in Daegu city, where weekly temperature and the morphological changes of the plants were mainly observed. Urban forests had different temperature depending on where each was located in the urban area. The difference of temperature in forests in and outside the urban area was verified by SPSS (Statistical Package for the Social Sciences), which divided the urban forests into about three groups; the one located outside the city, another group located in the middle of the city, and the other located close to the outside forests. The forests located in the middle of the city were showing the earlier leaf burst timing and leaf growth performance, while forests, distributed outside the city, were showing relatively late leaf burst timing and leaf performance.