• Human Ecology Research
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• v.56 no.5
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• pp.473-491
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• 2018

This study identifies Japanese study content on heat stroke prevention measures using clothes, provides basic data for quantitative wearing assessment studies, presents a developmental direction for those, and helps invigorate further research. Studies were collected concerning clothing-based heat stroke measures in order to analyze the following factors: current status of heat stroke by industry and working environment, heat stroke and body cooling method, clothing microclimate and air circulation in a hot environment, hot environments and wearable sensors, and heat stress reduction and skin exposure. The current WBGT standard does not consider the diversity of wearing clothes according to the working environment. Therefore, it is preferable to add a correction value in consideration of design, materials, and ventilation to prevent heat strokes. For the heat stroke and body cooling method, wearing water-perfused clothing is effective to reduce heat stress and maintain exercise ability. Changing the material and design of clothing or wearing air-conditioned clothing can improve ventilation and the clothing microclimate. However, further evaluation is needed on the effectiveness of air-conditioned clothing as a heat stroke prevention product. The measurement method using a wearable sensor can provide real-time data on the body response due to working in a hot environment. Therefore, it is an effective alarm for heat stroke. Skin exposure area and heat dissipation efficiency should be considered to prevent heat stroke. Reducing the covering area by exposing the head, neck, and limbs, and wearing breathable material can prevent heat stroke from increased body temperature.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.4
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• pp.135-139
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• 2017

In recent years, the optical fiber laser has been widely used in industrial fields due to its excellent economical efficiency and its suitability for industrial applications. This usage has increased even further since the KW class Laser was developed. In this paper, structural analysis and heat transfer analysis of a 500W class optical fiber laser end cap module was performed. The stability of end cap housing with the efficient heat dissipation structure of a 500W-class end cap was evaluated. This research determined the optimal design that should be applied to the design and evaluation of future KW class laser output modules.

• Journal of Energy Engineering
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• v.28 no.4
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• pp.35-41
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• 2019

In order to overcome these disadvantages, the halogen light source, which was previously used as a vehicle fog light, has increased power consumption and a short lifetime, and thus, an automobile light source is gradually being replaced with an LED. However, when the vehicle LED fog light is turned on, there is a disadvantage in reducing the life of the fog lamp due to the high heat generated from the LED. The heat generated by the LED inside the fog lamp is mainly emitted by the heatsink, but most of the remaining heat is released to the outside through convection. When cooling efficiency decreases due to convection, thermal energy generates heat to lenses, reflectors, and bezels, which are the main parts of lamps, or generates high temperatures in LED, thereby shortening the life of LED fog lights. In this study, we tried to improve the heat dissipation performance by convection in addition to the heat dissipation method by heat sink, and to determine the installation location of vents that can discharge the internal air or intake the external air of LED fog lamp for vehicle. Thermal fluid analysis was performed to ensure that the optimal data were reflected in the design. The average velocity of air increased in the order of Case3 and Case2 compared to Case1, which is the existing prototype, and the increase rate of Case3 was relatively higher than that of other cases. This is because the vents installed above and below the fog lamps induce the convective phenomena generated according to the temperature difference, and the heat is efficiently discharged with the increase of the air speed.

• Korean Journal of Materials Research
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• v.20 no.4
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• pp.204-209
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• 2010

Recent high efficiency electronic devices have been found to have heat emission problems. As for LEDs, an excessive increase in the device temperature causes a drop of the luminous efficiency and circuit lifetime. Therefore, heat release in the limited space of such electronic parts is very important. This is a study of the possibility of using a coating of carbon materials as a solution for the thermal emission problem of electronic devices. Powdered carbon materials, cokes, carbon blacks, amorphous graphite, and natural flakes were coated with an organic binder on an aluminum sheet and the subsequent thermal emissivity was measured with an FT-IR spectrometer and was found to be in the range of $5{\sim}20\;{\mu}m$ at $50^{\circ}C$. The emissivity of the carbon materials coated on the aluminum sheet was shown to be over 0.8 and varied according to carbon type. The maximum thermal emissivity on the carbon black coated-aluminum surface was shown to be 0.877. The emissivity of the anodized aluminum sheets that were used as heat releasing materials of the electronic parts was reported to be in the range of 0.7~0.8. Therefore, the use of a coating of carbon material can be a potential solution that facillitates heat dissipation for electronic parts.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.2
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• pp.158-163
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• 2013

In this paper, thermal analysis of heatsink for 30 W class Chip-on-Board (COB) LED light source is performed by using SolidWorks Flow Simulation package. In order to increase the convection heat transfer, number of fin and shape of the heatsink is optimized. Furthermore, a copper spread is applied between the COB LED light source and the heatsink to mitigate the heat concentration on the heatsink. With the copper spread, the junction temperature between the COB LED light source and the heatsink is $50.9^{\circ}C$, which is $5.4^{\circ}C$ lower than the heatsink without the copper spread. Due to the improvement of the junction temperature, the light output is improved by 5.8% when the LED light source is stabilized. The temperature difference between the simulation and measured result of the heatsink with the copper spread is within $2^{\circ}C$, which verifies the validity of the thermal design method using a simulation package.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.11
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• pp.1575-1581
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• 2014

In this paper, eddy current loss, iron loss and heat transfer of PMSG with 2,000kW capacities were analyzed for wind turbine. The PMSG with 3 split magnet was analyzed using ansoft maxwell commercial program and, generator was tested by Back to Back converter with no load condition at laboratory. Rotor surface temperature was measured by Pt100 sensors for investigating heat transfer from rotor to atmosphere. The simulation results shows 27.4kW eddy current loss in no load condition and 50.2kW eddy current loss in rated load condition with 3 split magnet, and also shows 4.3kW iron loss in no load condition and 7.3kW iron loss rated load condition. The heat transfer coefficient of convection between rotor surface and atmosphere was investigated by $9.6W/m^2{\cdot}K$. Therefore the heat transfer from rotor to atmosphere was about 17kW(54%) and from rotor to air-gap was about 14.6kW(46%) in no load condition. It is identified that the cooling system for stator have to include the 46% of iron loss, and heat dissipation structure of rotor surface have to be suggested and designed for efficiency improvement of generator.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.592-597
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• 2013

The heat generated at the motor and inverter inside the electric compressor of inverter built-in type is mainly cooled by refrigerant and generally, there is not a thermal problem. However, the close relation of heat transfer from the motor and inverter parts to the compression part affects on compressor efficiency. Also, according to the surrounding environment and system operation condition, the increased temperature of the motor and inverter can affect the power density of the motor system, and especially, the inverter may be prevented to operate by the temperature limits. In this study, we performed thermo-flow analysis of electric compressor motor system, and investigated the heat dissipation enhancement of the motor and inverter. The motor part in the operation region of the electric compressor was generally maintained at low temperature and the inverter part at high compressor speed was lower temperature than the temperature limit of $85^{\circ}C$. However, the case of the inverter at low speed harsh condition was in excess of $10^{\circ}C$. Therefore, in order to solve the thermal problem, the heat reduction technology of the motor and inverter is essential as well as the improvement of flow path in the compressor.

• Proceedings of the KWS Conference
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• v.43
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• pp.213-215
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• 2004

Water jet propulsion system has high efficiency on middle to high speed, and it provides better safety than conventional screw propeller because it has not projected propeller and rudder. So many leisure boat and high-speed ferries use this propulsion system. We developed water-jet propulsion unit for small planning boat, and launched that in the boat, after that we tested water-jet unit in the lake. As a result, we certify heat dissipation at the bearing housing and reverse duct's shape for neutral position are important at the design, and alignment water-jet unit and keel line are important at the launching, and ship's resistance performance and jet's propulsion performance also are needed to consideration.

• Journal of Power Electronics
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• v.13 no.5
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• pp.779-786
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• 2013

A highly efficient sustaining driver is proposed for plasma display panels (PDPs). When the PDP is charged and discharged, the proposed sustaining driver employs an address voltage source used in an addressing period. A voltage source is used for fully charging the panel to the sustaining voltage, and an initial inductor current helps the panel discharge to 0 V. The resonance between the panel and an inductor is made by shifting the voltage and current bias level when charging and discharging the panel. As a result, the proposed circuit can reduce power consumption, switching loss, heat dissipation, and production cost. Experimental results of a 42-inch PDP are provided to verify the operation and features of the proposed circuit.

• Journal of Korea Foundry Society
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• v.38 no.3
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• pp.60-65
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• 2018

In the present study, the characteristics of Mg inverter cases for hybrid cars are investigated. Concerns over the use of lightweight materials to reduce energy use and to mitigate emission problems are inevitable in the twenty-first century. Magnesium is a promising material for the manufacturing of lightweight parts. Several cases for thermal cooling channels have been designed and simulated, and the effects of materials and coatings on the thermal cooling efficiency have been discussed. The effects of the coating thickness on heat extraction in an Mg inverter housing case using the PEO (plasma electrolyte oxidation) coating method were also discussed. In order to produce an inverter case by the diecasting process, the filling sequence and cooling behavior during the diecasting process were simulated. The optimized process conditions from the simulation result were then used in a trial diecasting experiment.