• Applied Science and Convergence Technology
• /
• v.24 no.5
• /
• pp.136-141
• /
• 2015

We studied the compact anode design to develop 100 kW rotating anode X-ray tube with large focal spot 1.2 mm, small focal spot 0.6 mm and tube voltage 150 kV for large hospital digital radiography using computer thermal simulation. The larger thermal radiation effect in a high vacuum can reduce the temperature of anode so the method to increase the surface area of anode is investigated. The anode has the multi-tier shape at the back side of TZM body of anode and also bigger diameter of anode. The number of multi-tiers was varied from 6 to 15 and the diameter of anode was also varied from ${\Phi}74$ to ${\Phi}82$. From ANSYS transient thermal simulation result, we could obtain $1056.4^{\circ}C$ anode maximum temperature when applying 100 kW input power at 0.1 second on target focal track which is less than $1091^{\circ}C$ of the conventional 75 kW X-ray tube with reduced anode weight by 15.5% than the conventional anode. The compact anode of reduced anode weight is able to improve the unwanted noise when the rotor is rotating at high-speed and also reduce the rotational torque which the cost effective stator-coil is possible. It is believed that the anode with 15 ea multi-tiers using ${\Phi}82$ can satisfy with the specification of the anode heat capacity. From the results of this paper, it has been confirmed that the proposed compact anode can be used as the anode of 100 kW rotating anode X-ray tube for digital radiography.

• Solar Energy
• /
• v.17 no.2
• /
• pp.35-42
• /
• 1997

Thermal diode is a device which allows heat to be transferred in one direction by convection due to difference of density of fluid, and blocks heat flow in the opposite direction. Vertical plate for heat collection and radiation are of utility for design of thermal diode. It was considered the transient and steady state of air filled thermal diode with guide vane which combined rectangular and parallelogrammic shape enclosures. $Gr^*$ was kept constantly on $1.11{\times}10^{10}{\sim}1.4{\times}10^{10}$ and error range was ${\pm}3%$ during the experiment. Nu was examined when inclined angle are $15^{\cir\c}\;and\;45^{\circ}$ and, also the experiments was carried out with and without guide vane as well. Specially, Nu was linearly increased due to increase of $Gr^*$, and the effect of guide vane and dimensionless channel depth was sensitive. Developed state of temperature began at dimensionless time $0.5{\sim}0.6$ due to variation of inclined angle, which is characteristic of system.

• Journal of the Korean Solar Energy Society
• /
• v.23 no.1
• /
• pp.1-8
• /
• 2003

Various efforts to combine new high-tech materials with solar system have been progressed nowadays in order to improve the performance of the existing passive solar system. TIM(Transparent Insulation Material) replacing the conventional outer building envelope glazing as well as the wall is good example for this trend. TI integrated wall is a thermal mass wall with a special shaped TIM instead of using typical envelope materials The tested TIM type is a small(diameter 4mm and thickness 50mm) capillary tube of Okalux model and cement brick(density 1500kg/m3). The purpose of this study was to analyze the thermal performance through the actual measurements performed in a test cell. This study was carried out to justify the following issues. 1) the impact of Tl-wall over the temperature variations 2) the impact of mass wall surface absorptance over the transient thermal behavior and 3) the impact of thermal mass wall thickness over the temperature variations. Finally, as results indicated that the peak time of room temperature was shifted about one hour early when absorptance of thermal mass wall changed from 60% to 95% for the 190mm thickness thermal mass wall test case. the temperature difference of both surfaces of thermal mass wall surface showed about $23^{\circ}C$ during a day of March for the 380mm thickness thermal mass wall case. However, the thermal mass wall was over-heated by outside temperature and solar radiation in a day of May the temperature difference of both surfaces of thermal mass wall surface was indicated $10^{\circ}C$ and inside temperature was observed more than average 22C.

• Journal of Environmental Science International
• /
• v.25 no.8
• /
• pp.1115-1129
• /
• 2016

To analyze human thermal environments in protected horticultural houses (plastic houses), human thermal sensations estimated using measured microclimatic data (air temperature, humidity, wind speed, and solar and terrestrial radiation) were compared between an outdoor area and two indoor plastic houses, a polyethylene (PE) house and a polycarbonate (PC) house. Measurements were carried out during the daytime in autumn, a transient season that exhibits human thermal environments ranging from neutral to very hot. The mean air temperature and absolute humidity of the houses were $14.6-16.8^{\circ}C$ (max. 22. $3^{\circ}C$) and $7.0-12.0g{\cdot}m^{-3}$ higher than those of the outdoor area, respectively. Solar (K) and terrestrial (L) radiation were compared directionally from the sky hemisphere (${\downarrow}$) and the ground hemisphere (${\uparrow}$). The mean $K{\downarrow}$ and $K{\uparrow}$ values for the houses were respectively $232.5-367.8W{\cdot}m^{-2}$ and $44.9-55.7W;{\cdot}m^{-2}$ lower than those in the outdoor area; the mean $L{\downarrow}$ and $L{\uparrow}$ values were respectively $150.4-182.3W{\cdot}m^{-2}$ and $30.5-33.9W{\cdot}m^{-2}$ higher than those in the outdoor area. Thus, L was revealed to be more influential on the greenhouse effect in the houses than K. Consequently, mean radiant temperature in the houses was higher than the outdoor area during the daytime from 10:45 to 14:15. As a result, mean human thermal sensation values in the PMV, PET, and UTCI of the houses were respectively $3.2-3.4^{\circ}C$ (max. $4.7^{\circ}C$), $15.2-16.4^{\circ}C$ (max. $23.7^{\circ}C$) and $13.6-15.4^{\circ}C$ (max. $22.3^{\circ}C$) higher than those in the outdoor area. The heat stress levels that were influenced by human thermal sensation were much higher in the houses (between hot and very hot) than in the outdoor (between neutral and warm). Further, the microclimatic component that most affected the human thermal sensation in the houses was air temperature that was primarily influenced by $L{\downarrow}$. Therefore, workers in the plastic houses could experience strong heat stresses, equal to hot or higher, when air temperature rose over $22^{\circ}C$ on clear autumn days.

• Journal of Nutrition and Health
• /
• v.49 no.6
• /
• pp.429-436
• /
• 2016

Purpose: Solar ultraviolet (UV) radiation causes inflammation and matrix metalloproteinase (MMP) overexpression and extracellular matrix depletion, leading to skin photoaging such as wrinkle formation, dryness, and sagging. Activation of MMP is influenced by various molecules such as reactive oxygen species (ROS), proinflammatory cytokines, and transient receptor potential vanilloid type (TRPV)-1, which are increased in UV-irradiated skin cells. Aralia elata (AE) ethanolic extract was reported to inhibit ROS generation caused by UVB-irradiation in keratinocytes. In this study, we investigated the photoprotective effect of AE ethanolic extract on UVB-irradiated human keratinocytes (HaCaT) and human dermal fibroblasts (HDF). Methods: AE was freeze-dried, extracted in 70% ethanol, and concentrated. Skin cells were treated with AE extract for 24 h and then exposed to UVB ($55mJ/cm^2$). After 48 h of incubation, proinflammatory cytokines, MMP-1, type-1 procollagen, and TRPV-1 levels were measured by ELISA or Western blotting. Results: Treatment with AE extract ($100{\mu}g/mL$) significantly inhibited UVB-induced IL-6, IL-8, and $PGE_2$ production in HaCaT by 25.6%, 5.3%, and 70.2%, respectively, and also inhibited elevation of MMP-1 and TRPV-1 caused by UVB irradiation by 20.0% and 41.9%, respectively (p < 0.05). In HDF, AE extract treatment significantly inhibited both elevation of MMP-1 and reduction of type-1 procollagen caused by UVB irradiation (p < 0.05). In addition, type-1 procollagen was elevated by AE extract treatment in normal HDFs (p < 0.05). Conclusion: AE 70% ethanol extract has photoprotective ability via reduction of proinflammatory mediators, TRPV-1 and MMP-1 production, and elevation of collagen synthesis. Our findings suggest that AE extract might be a good natural material to protect against UVB-induced premature skin aging.

• The Korean Journal of Nuclear Medicine
• /
• v.28 no.1
• /
• pp.124-132
• /
• 1994

Radioactive iodine has been widely used in patients with thyroid cancer combined with surgical treatment. However, due to individual variations in absorption and excretion and uptake by tumor tissue of radioactive iodine, there are differences in therapeutic effect and adverse effects even if the same doses are administrated. So this study compared the therapeutic effect and radiation hazard by measuring internal radiation dose. Of total 27 patients with well differentiated thyroid cancer who had been thyroidectomized, we administered radioactive iodine 100 mCi, 150 mCi, 200 mCi. According to BEL DOSIMETRY PROTO-COL, beta and gamma ray dose were estimated from a pelt of the logarithm of the percent of dose per liter of whole blood versus day, and percent dose retained versus day using somilogarithmic paper, respectively. 1) Physical dose to whole blood averaged $56.54{\pm}13.02$ rad in 100 mCi administered group, $76.83{\pm}19.97$ rad in 150 mCi administered group, $95.08{\pm}25.51$ rad in 200 mCi administered group and there has been a significant correlation among the groups. 2) Mean percent dose retained 48 hours later was 26.34%. 3) There was no significant correlation of physical dose between absence and presence of metastasis. 4) 17 of 19 patients who has been followed up with TSH and serum throglobulin, Thallium scan were successfully ablated by radioactive iodine. 5) Leukocyte, lymphocyte, neutrophil, platelet counts all deelined in 4.6 weeks and most of all were restored 3 months later. 6) There was no significant correlation between physical dosimetry and biologic dosimetry. Generally administered doses of radioactive iodine (100-200 mCi) to patients with thyroid cancer postoperatively had developed transient bone marrow suppression and minimal chromosomal aberration, but they were within safety dose to blood (200 rad). And there has been no significant differences in residual dose 48 hours later between Korean and western people.