• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.3
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• pp.457-472
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• 1997

We studied the temperature distribution and heat transfer characteristics of TEFC induction motor with thermal network program for more efficient design and better cooling performance of it. We knew the characteristics and the windage loss of outer cooling fan from fan test experiments. Frame axial and peripheral heat transfer coefficients and endwinding heat transfer coefficient were measured by various model experiments and then, compared with other experimental results. Frame was the main heat transfer surface, load-side and fan-side surface were not thermally symmetric from the heat flux distribution analysis. Steady and unsteady temperature distributions were measured by real motor experiments. From the results, we knew that rotor surface temperature was higher than coil temperature and the hottest spot in the coil was loadside endwinding outside surface. We compared the simulation results with those of real motor test and the two results showed a good agreement.

• Journal of the Korean Society for Heat Treatment
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• v.23 no.5
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• pp.263-268
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• 2010

This investigation was focused on the low temperature tensile properties, phase change, changes in nitrogen content and corrosion resistance in the 22Cr-5Ni-3Mo duplex stainless steel after high temperature gas nitriding and solution annealing (HTGN-SA). From the HTGN-SA treatment, the duplex (ferrite + austenite) phase changed into austenite single phase. The nitrogen content of austenite single-phase steel showed a value of ~0.54%. For the HTGN-SA treated austenitic steel, tensile strength increased with lowering test temperature, on the other hand elongation showed the maximum value of 28.2% at $-100^{\circ}C$. The strain-induced martensitic transformation gave rise to lead the maximum elongation. After HTGN-SA treatment, corrosion resistance of the austenite single-phase steel increased remarkably compared with HTGN- treated steel.

• Journal of Environmental Science International
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• v.27 no.6
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• pp.467-475
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• 2018

The lifetime of the electrode is one of the most important factors on the stability of the electrode. Since the lifetime of the DSA (Dimensionally stable anode) electrode is long, an accelerated lifetime test is required to reduce the test time. Beacuse there is no basis or standard method for accelerated lifetime testing, many researchers use different methods. Therefore, there is a need for basis and methods for accelerated lifetime testing that other researchers can follow. We designed a reactor system for accelerated lifetime testing and planned specific methods. Reactor system was circulating batch reactor. Reactor volume and cooling water tank were 12.5 L and 100 L, respectively. Electrode size was $2cm{\times}3cm$ (real electrolysis area, $5cm^2$). In order to maintain the harsh conditions, accelerated lifetime test was carried out in a high current density ($0.6A/cm^2$) and low electrolyte concentration (NaCl, 0.068 mol/L). Maintaining a constant temperature was an important operation parameter for exact accelerated lifetime test. As the accelerated lifetime test progressed, the active component of electrode surface was consumed and desorption occurred. At the point of 5 V rise, corrosion of the surface of the base material(titanium) also started.

• Restorative Dentistry and Endodontics
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• v.27 no.4
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• pp.370-381
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• 2002

This study was performed to evaluate the temperature rise on various position of the Buchanan plugger, the peak temperature of plugger's type and the temperature change by its touching time of heat control spling. The heat carrier system 'System B' (Model 1005, Analytic Technologies, USA) and the Buchanan's plug-gers of F, FM, M and ML sizes are used for this study. The temperature was set to 20$0^{\circ}C$ which Dr. Buchanan's "continuous wave of condensation" technique recommended on digital display and the power level on it was set to 10. In order to apply heat on the Buchanan's pluggers, the heat control spring was touched for 1, 2, 3, 4 and 5 seconds respectively. The temperature rise on the surface of the pluggers were measured at 0.5 mm intervals from tip to 20 mm length of shank using the infrared thermography (Radiation Thermometer-IR Temper, NEC San-ei Instruments, Ltd, Japan) and TH31-702 Data capture software program (NEC San-ei Instruments, Ltd, Japan). Data were analyzed using a one way ANOVA followed by Duncan's multiple range test and linear regression test. The results as follows. 1. The position at which temperature peaked was approximately at 0.5 mm to 1.5 mm far from the tip of Buchanan's pluggers (p<0.001). The temperature was constantly decreased toward the shank from the tip of it (p<0.001). 2. When the pluggerss were heated over 5 seconds, the peak temperature by time of measurement revealed from 253.3$\pm$10.5$^{\circ}C$ to 192.1$\pm$3.3$^{\circ}C$ in a touch for 1 sec, from 218.6$\pm$5.$0^{\circ}C$ to 179.5$\pm$4.2$^{\circ}C$ in a touch for 2 sec, from 197.5$\pm$3.$0^{\circ}C$ to 167.5$\pm$3.7$^{\circ}C$ in a touch for 3 sec, from 183.7$\pm$2.5$^{\circ}C$ to 159.8$\pm$3.6$^{\circ}C$ in a touch for 4 sec and from 164.9$\pm$2.$0^{\circ}C$ to 158.4$\pm$1.8$^{\circ}C$ in a touch for 5 sec. A touch for 1 sec showed the highest peak temperature, followed by, in descending order, 2 sec, 3 sec, 4 sec. A touch for 5 sec showed the lowest peak temperature (p<0.001). 3. A each type of pluggers showed different peak temperatures. The peak temperature was the highest in F type and followed by, in descending order, M type, ML type. FM type revealed the lowest peak temperature (p<0.001). The results of this study indicated that pluggers are designed to concentrate heat at around its tip, its actual temperature does not correlate well with the temperature which Buchanan's "continuous wave of condensation" technique recommend, and finally a quick touch of heat control spring for 1sec reveals the highest temperature rise.

• Journal of Electrical Engineering and Technology
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• v.1 no.3
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• pp.376-380
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• 2006

Temperature distribution measured to estimate the condition of an electrical apparatus is an absolute reference for the apparatus conditions and the difference between the reference temperature and the current temperature. Because of passive thermography, without the external thermal stimulation, the difference in surface temperature between the region of interest and back ground shows that the results can apply only to the estimation or the monitoring for the condition of loose terminal and the overload pertaining to the rise in temperature. However, a thermal diffusion in the active thermography is differently generated by the structure and condition of the surface and subsurface. This paper presents a nondestructive test using this behavior and deals with the results by heat injection and cooling to the apparatus. The buried discontinuity of subsurface could be detected by these techniques.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.114-115
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• 2021

The research team conducted a series of studies to use CGS as fine aggregate for concrete. In this paper, through the adiabatic temperature rising test, CGS' hydration heating performance and its usability as a mass concrete hydration heating agent were reviewed. According to the analysis, the maximum temperature of the mix of OPC 100 was 53.7℃, and the temperature of CGS 50% was 45.2℃, which was 8.5℃ lower than the OPC 100.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.292-295
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• 2008

In a SCWR (SuperCritical pressure Water cooled Reactor), the coolant temperature initially at below the pseudo-critical temperature at the bottom of a reactor core increases as the coolant flows upward through the sub-channels of the fuel assemblies, and it finally becomes higher than the pseudo-critical temperature when it leaves the reactor core. At certain conditions, heat transfer deterioration occurs near the pseudo-critical temperature and it may cause a drastic rise of the fuel surface temperature resulting a fuel failure. Therefore, an accurate estimation of the heat transfer coefficient is very important for the thermal-hydraulic design of a reactor core. An experiment on heat transfer to the vertically upward flowing $CO_2$ at a supercritical pressure in a circular tube were performed at KAERI. The internal diameter of the test section is 6.32 mm, which corresponds to the hydraulic diameter of a sub-channel in the conceptional design proposed by KAERI. The test range of the mass flux is 285 to 1200 kg/m$^2$s and the maximum heat flux is 170 kW/m$^2$. The inlet pressure is maintained at 8.12 MPa, which is 1.1 times the critical pressure. A new correlation, which covers both the normal and deterioration heat transfer regimes was proposed and compared with the estimations by exiting correlations.

• Structural Engineering and Mechanics
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• v.84 no.5
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• pp.575-590
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• 2022

In this paper, bond-slip behavior of high strength concrete filled circular steel tube (HSCFCST) after elevated temperatures treatment was studied. 17 specimens were designed for push-out test. The influence was discussed as following parameters: (a) concrete strength, (b) constant temperature, and (c) bond length. The results showed that (1) after elevated temperatures treatment, the bond strength of the HSCFCST specimens increased first and then decreased with temperature rising; (2) the bond strength increased with the increase of concrete strength at room temperature, while the influence subsided after elevated temperatures treatment; (3) the strain of the circular steel tube was distributed exponentially along its length, the stress changed from exponential distribution to uniform distribution with the increase of load; (4) the bond damage process was postponed with the increase of constant temperature; and (5) the energy consumption capacity of the bonding interface increased with the rise of concrete strength and constant temperature. Moreover, computational formulas of ultimate and residual bond strength were obtained by regression, and the bond-slip constitutive models of HSCFCSTs after elevated temperatures was established.

• Journal of the Korean Society of Radiology
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• v.16 no.6
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• pp.751-759
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• 2022

Currently, ultrasound examination for diagnostic ultrasound and health examination purposes is widely used, and it is showing an increasing trend due to the application of health insurance. However, the risk of ultrasound has not been clearly identified so far, and in this study, surface and deep temperature changes according to frequency and mode were measured by using a tissue mimicking phantom and TI and MI values were compared. A simulated phantom was manufactured by adding a small amount of kappa-caraginan powder with acoustic characteristics similar to that of the human body and potassium chloride for solidification, and the change of surface and depth temperature was measured using a surface thermometer and a probe thermometer. As a result, the convex probe using low frequency showed a higher temperature increase than the linear probe using high frequency, so there was a significant difference, and the temperature increase was the highest on the surface, and the depth of 1cm showed a temporary temperature increase, but there was no significant temperature change. There was no change in the deep temperature of 5 cm to 15 cm, and the TI and MI values did not change during the test time. Since only the surface temperature rose during the 15-minute test and there was no temperature change in the core, so it is not expected to show a temperature change that is harmful to the human body. However, it is thought that prolonged examination of one area may cause temperature rise, so it should be avoided.

• The Korean Journal of Applied Statistics
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• v.34 no.3
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• pp.439-447
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• 2021

Due to the frequent emergence of global abnormal climates, related studies on meteorological change is being actively proceed. However, the research on trend analysis using weather data accumulated over a long period of time was insufficient. In this study, the trend of temperature time series data accumulated from automated surface observing system (ASOS) for 40 years was analyzed by using a non-parametric analysis method. As a result of the Mann-Kendall test on the annual average temperature and seasonal average temperature time series data in South Korea, it has shown that an upward trend exists. In addition, the result of calculating the Sen's slope, which can determine the degree of tendency before and after the searched change point by applying the Pettitt test, recent data after the fluctuation point confirmed that the tendency of temperature rise was even greater.