• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07b
• /
• pp.1135-1138
• /
• 2003

The transformer is major equipment in power receiving and substation facilities. Necessary conditions required for the transformer are compactness, lightness, high reliability, economic advantages, and easy maintenance. The pole-mount transformer installed in distribution system is acting direct role in supply of electric power and it is electric power device should drive for long term. Most of modem transformer are oil-filled transformer and accident is happening considerable. The mold transformers have been widely used in underground substations in large building and have some advantages in comparison to oil-transformer, that is low fire risk, excellent environmental compatibility, compact size and high reliability. In addition, the application of mold transformer for outdoor is possible due to development of epoxy resin. The mold transformer generally has cooling duct between low voltage coil and high voltage coil. A mold transformer made by one body molding method has been developed for small size and low loss. One body molding transformer needs some cooling method because heat radiation between each winding is difficult. In this paper, The thermal analysis of pole mount mold transformer with one body molding by duct condition is investigated and the test result of temperature rise is compared with simulation data.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.49 no.5
• /
• pp.407-415
• /
• 2021

The performance of satellite parts must be verified under the space orbit environment before the launch. This paper develops a model formula considering the thermal environment such as conduction, radiation, heat loss and internal heating between satellite parts and a small thermal vacuum chamber for thermal vacuum tests. System identification is carried out using test data from 20 recent thermal vacuum tests conducted by the Korea Aerospace Research Institute. It is verified that the model formula and the identification results are valid, except when the heating of the functional test of the test specimen is not constant.

• Journal of Bio-Environment Control
• /
• v.11 no.4
• /
• pp.151-156
• /
• 2002

Root zone cooling, such as soil or nutrient solution cooling, is less expensive than air cooling in the whole greenhouse and is effective in promoting root activity, improving water absorption rate, decreasing plant temperature, and reducing high temperature stress. The heat transfer of a soil cooling system in a plastic greenhouse was analyzed to estimate cooling loads. The thermal conductivity of soil, calculated by measured heat fluxes in the soil, showed the positive correlation with the soil water content. It ranged from 0.83 to 0.96 W.m$^{[-10]}$ .$^{\circ}C$$^{[-10]}$ at 19 to 36％ of soil water contents. As the indoor solar radiation increased, the temperature difference between soil surface and indoor air linearly increased. At 300 to 800 W.m$^{-2}$ of indoor solar radiations, the soil surface temperature rose from 3.5 to 7.$0^{\circ}C$ in bare ground and 1.0 to 2.5$^{\circ}C$ under the canopy. Cooling loads in the root zone soil were estimated with solar radiation, soil water content, and temperature difference between air and soil. At 300 to 600 W.m$^{-2}$ of indoor solar radiations and 20 to 40％ of soil water contents,46 to 59 W.m$^{-2}$ of soil cooling loads are required to maintain the temperature difference of 1$0^{\circ}C$ between indoor air and root zone soil.

• The Korean Journal of Physiology and Pharmacology
• /
• v.14 no.3
• /
• pp.157-161
• /
• 2010

Heat shock proteins (HSPs) are specifically induced by various forms of stress. Hsp70.1, a member of the hsp70 family is known to play an important role in cytoprotection from stressful insults. However, the functional role of Hsp70 in motor function after spinal cord injury (SCI) is still unclear. To study the role of hsp70.1 in motor recovery following SCI, we assessed locomotor function in hsp70.1 knockout (KO) mice and their wild-type (WT) mice via the Basso, Beattie and Bresnahan (BBB) locomotor rating scale, before and after spinal hemisection at T13 level. We also examined lesion size in the spinal cord using Luxol fast blue/cresyl violet staining. One day after injury, KO and WT mice showed no significant difference in the motor function due to complete paralysis following spinal hemisection. However, when it compared to WT mice, KO mice had significantly delayed and decreased functional outcomes from 4 days up to 21 days after SCI. KO mice also showed significantly greater lesion size in the spinal cord than WT mice showed at 21 days after spinal hemisection. These results suggest that Hsp70 has a protective effect against traumatic SCI and the manipulation of the hsp70.1 gene may help improve the recovery of motor function, thereby enhancing neuroprotection after SCI.

• KIEAE Journal
• /
• v.16 no.6
• /
• pp.167-172
• /
• 2016

Purpose: The solar water heater with natural circulation has been used for several decades in the world as it is automatically operated without a pump and controller and is easy to maintain and repair. After the subsidy was offered from 2012, the solar water heater with natural circulation is becoming increasingly popular in Korea. Recently, the development of a wall-integrated solar water heater, which improves the applicability of buildings and prevents the overheating in the summer, is being developed. On the other hand, the design and performance evaluation data of solar water heaters are very inadequate, and analysis of heat and flow is required to develop a new type of solar water heater. Method: Therefore, in this study, we proposed a new simplified system analysis model that reflects heat and pressure loss from the test results of KS B ISO 9806-1 (Solar collector test method), assuming that the collector is a simple pipe system, the validity of which was verified through experiments. Result: As a result, first, the RMSE of the system circulation flow rate and the average temperature of the inlet and outlet of the collector according to the experimental results and the simulation are 0.05563 and 0.88530, respectively, which are very consistent. Secondly, the mass flow rate is increased linearly with the increase of the solar radiation, and the mass flow rate is 0.0104 ~ 0.0180kg/s in the range of $200{\sim}380W/m^2$ of solar irradiance. Compared with the test flow rate 0.0764kg / s of the test collector, it showed a level of less than 20%.

• 한국전산유체공학회:학술대회논문집
• /
• 2002.10a
• /
• pp.133-138
• /
• 2002

A 3-D axisymmetric computer program is developed to predict the NO behavior in SNCR system for the stoker incinerator with the waste treatment capacity, 200ton/day. To this end a turbulent reacting flow field calculation is made using proper assumption and empiricism. The stoker bed is assumed to be a homogeneous waste-volatilized gaseous state. The initial composition or reactants are assumed based on the data of the ultimate analysis. Turbulent is resolved by k-e model and turbulent reaction is handled by eddy-breakup model harmonized with empirical chemistry data for gaseous combustion, NO and urea reaction. The liquid droplet is traced by Lagrangian method incorporated by aerodynamic drag, Coriolis and crntrifugal forces. Radiation is treated by sensible heat loss model. Calculation results are in good agreement with experimental data at the outlet of post combustion chamber in Daejon 4th industrial complex. The flue gas shows the temperature range of $900\sim1000^{\circ}C$, velocity of 5m/s and NO concentration of 140ppm at the exit while the measured temperature, flue gas velocity and NO concentration are $967^{\circ}C$, $3\sim4m/s$ and $100\sim200ppm$respectively. Using the developed computer program a parametric study has been made with the variation of heat content of waste, castable length and SNCR variables for the determination of proper injector location. In general, the calculated results are consistent and physically acceptable.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.30 no.2
• /
• pp.110-115
• /
• 2010

This study was conducted to estimate the feasibility using thermal image measurement that is applicable to internal leak diagnosis for the power plant valve. Abnormal heating of valve surface associated with high temperature steam f10w toward valve outlet side in the condition of low temperature is a primary indicator of leakage problems in high temperature and pressure valves. Thermal imaging enables to see the invisible thermal radiation that may portend impending damage before their condition becomes critical. When steam flow in valve outlet side in the condition of low temperature is converted into heat transmitted through the valve body due to the internal leakage in valve. The existence of abnormally increasable leakage rate in the valve will result in abnormally high levels of heat to be generated that can be quickly identified with a thermal image avoiding energy loss or damage of valve component. From the experimental results, it was suggested that the thermal image measurement could be an effective way to precisely diagnose and evaluate internal leak situation of valve.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.33 no.4
• /
• pp.336-341
• /
• 2013

In this paper, the design concept of a low-temperature vacuum blackbody was described, and thermophysical model of the blackbody was numerically evaluated. Also the working performance of low-temperature vacuum blackbody was evaluated using infrared camera system. The blackbody system was constructed to operate under high-vacuum conditions ($2.67{\times}10^{-2}$ Pa) to reduce temperature uncertainty, which is caused by vapor condensation at low temperatures usually below 273 K. In addition, both heat sink and heat shield including cold shield were installed around radiator to prevent heat loss from the blackbody. Simplified mathematical model of blackbody radiator was analyzed using modified Stefan-Boltzmann's rule. The infrared radiant performance of the blackbody was evaluated using infrared camera. Based on the results of measurements, and simulation, temperature stability of the low-temperature vacuum blackbody demonstrated that the blackbody system can serve as a highly stable reference source for the calibration of an infrared optical system.

• International Journal of Highway Engineering
• /
• v.13 no.4
• /
• pp.19-28
• /
• 2011

This study developed a solar radiation reflection pavement, so called a cool pavement, to lessen the urban heat island effect by coating a pavement surface with acrylic resins mixed with light-colored pigments. From a laboratory test, simulating solar heating process in pavements, the cool pavement reduced more than $12^{\circ}C$ of pavement temperature at $60^{\circ}C$ compared to a control porous pavement. With the increase of the mixing ratio of the pigments to acrylic resins, the temperature reduction effect increased, but its workability became worse due to higher viscosity. As a result, an appropriate mixing ratio was determined as 15%. The cool pavement had better durability than the control pavement: One quarter of Catabro loss and twofold dynamic stability. Its adhesion was also higher enough not to be debonded under traffic loading. In-situ noise and friction tests conducted in two field sites showed that the cool pavement reduced its noise level by 3.7dB in average and increased its friction level by 30% compared to the control pavement. The permeability of the cool pavement was little lower than the control pavement, but higher enough to satisfy the minimum requirement for porous pavements.

• Korean Journal of Food Science and Technology
• /
• v.35 no.5
• /
• pp.877-883
• /
• 2003

Multi-degradable master hatch (M/B) was prepared and 0.05 mm polyethylene (PP) food packaging films containing 0, 10, and 20% M/B were manufactured by inflation film processing. The films were exposed to UV radiation, fungi, and heat in order to observe their photolysis, biodegradability, and thermal degradability, respectively. While pure PP film maintained more than 70% of its original elongation after 8 weeks of UV radiation, an almost perfect loss in the elongation of PP film containing 20% M/B was observed. Significant decreases in elongation of PP films by heat treatment $(68{\pm}2^{\circ}C)$ were also found in samples containing the multi-degradable M/B. By observing changes in film surface after the inoculation of fungi using scanning electron microscopy (SEM), the biodegradability of plastic film could be accelerated with the addition of multi-degradable M/B. The results of the mulching test in yard showed that adding multi-degradable M/B can effectively degrade plastic films in natural environmental conditions without interrupting the growth of plants.