• Steel and Composite Structures
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• v.36 no.3
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• pp.249-259
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• 2020

In this work, a novel three-dimensional model in the generalized thermoelasticity for a homogeneous an isotropic medium was investigated with diffusion, under the effect of thermal loading due to laser pulse in the context of Green-Lindsay theory was investigated. The normal mode analysis technique is used to solve the resulting non-dimensional equations of the problem. Numerical results for the displacement, the thermal stress, the strain, the temperature, the mass concentration, and the chemical potential distributions are represented graphically to display the effect of the thermal loading due to laser pulse and the relaxation time on the resulting quantities. Comparisons are made within the theory in the presence and absence of laser pulse.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1251-1255
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• 2009

Snow melting system is adapted for safety and environment sides. Geothermal System has some problem of unbalance between summer and winter heat loads. Snow melting system with piping system is widely adapted in Japan. In this paper, the variation of road surface temperature along time for heating load is investigated. And for checking the difference between electrical melting system and piping melting system, other design parameters is investigated.

• Journal of the Semiconductor & Display Technology
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• v.10 no.4
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• pp.89-94
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• 2011

In recent years there have been considerable attentions on nanoimprint lithography (NIL) by the display device and semiconductor industry due to its potential abilities that enable cost-effective and high-throughput nanofabrication. A major disadvantage of thermal NIL is the thermal cycle, that is, heating over glass transition temperature and then cooling below it, which requires a significant amount of processing time and limits the throughput. One of the methods to overcome this disadvantage is to improve the cooling performance in NIL process. In this paper, a numerical analysis model of cooling system in thermal NIL was development by CAD/CAE program and the performance of the cooling system was analyzed by the model. The calculated temperatures of nanoimprint device were verified by the measurements. By using the analysis model, the case that the cooling material is replaced by liquid nitrogen is investigated.

• Journal of Korea Foundry Society
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• v.2 no.2
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• pp.10-17
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• 1982

This study has been carried out to determine the change of mechanical properties and microstructures by the heattreatment to relieve the residual stresses for gray cast irons. The results have been obtained from the experiment as follows; 1) The annealing above $600^{\circ}C$ for the stress relieving of gray cast iron decrease the tensile strength and hardness 2) The decrease reates of tensile strength and hardness of gray cast iron after annealing above $600^{\circ}C$ are increased with increasing the holding time. 3) The gray cast iron containing the elements of Mn, Cr has increased the heating temperature for the decrease of tensile strength and hardness. 4) The decrease of mechanical properties by annealing are assumed that the formation of ferrite takes placed from the decomposition of eutectoid cementite in the matrix.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.246-247
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• 2007

In recent, there have been several developments in lamp technology that promise savings in electrical power consumption and improved quality of the lighting space. Above ail, the advantage of ring-shaped electrodeless fluorescent lamp is the removal of internal electrodes and heating filaments that are a light-limiting factor of conventional fluorescent lamps. Therefore, the life time of ring-shaped electrodeless fluorescent lamps is substantially higher than that of conventional fluorescent lamps and last up to 60,000 hours and is intended as a high efficacy replacement for the incandescent reflector lamp in many applications. In this paper, when appling the electrodeless lamp in luminaire, We analyzed change of optical and electrical characteristics.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.1
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• pp.183-192
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• 2014

In this work, the mixture formation and atomization characteristics of biodiesel fuel were reviewed under various test conditions for the optimization of compression-ignition engine fueled with biodiesel. To achieve these, the effect of nozzle caviting flow, group-hole nozzle geometry and injection strategies on the injection rate, spray evolution and atomization characteristics of biodiesel were studied by using spray characteristics measuring system. At the same time, the fuel heating system was installed to obtain the effect of fuel temperature on the biodiesel fuel atomization. It was revealed that cavitation in the nozzle orifice promoted the atomization performance of biodiesel. The group-hole nozzle geometry and split injection strategies couldn't improve it, however, the different orifice angles which were diverged and converged angle of a group-hole nozzle enhanced the biodiesel atomization. It was also observed that the increase of fuel temperature induced the quick evaporation of biodiesel fuel droplet.

• Journal of Hydrogen and New Energy
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• v.30 no.6
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• pp.578-584
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• 2019

The occurrence of white plume in the cooling tower is phenomenon that the steam in the air through the cooling tower fan is condensed again by the cold ambient air to become saturated moist air. Accordingly, this can cause many problems like spoiling landscape around the cooling tower, odor of ambient air, falling accident by frozenness in the winter, and traffic accident, etc. This study was to install the heat exchanger in the inside of the cooling tower in order to prevent the white plume phenomenon in the cooling tower without affecting the performance of cooling tower. In addition, this study was to discharge the part of cooling water into the atmosphere through the recirculation of heat exchanger after creating dry air by heating the saturated moist air to the dew point temperature. At that time, this study was to conduct the experimental study in order to secure the optimal design data to prevent the white plume in the cooling tower because it checked the dry·moist temperature and relative humidity in the inside·outside of cooling tower on the moist air, and evaluated the performance of the heat exchanger.

• KIEAE Journal
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• v.10 no.1
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• pp.19-24
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• 2010

Modern people are spending most of time in interior area. Indoor air environmental problem is one of the most effective factors influenceable to human health. Furthermore, saving energy and making ventilation system for pleasant indoor environment are necessary when it is faced shortage of energy over the world. In our country's case, it is already imposed that required quantity of air ventilation in buildings is 0.7 times per hour on "The regulation on building engineering system". As on the rise of the interests about Indoor air environment, Heat and Carbon dioxide emissions from User's metabolism, activity, furniture, and construction materials etc. could be the causes of Indoor air pollution. If these materials stays in Indoor air for so long, it could directly influence the user's health condition with a disease. As of building's sterilization improved that raised more mechanical ventilation. It also leads much energy waste in a period of high price of fossil fuel. Therefore, the way that saves energy and effective control of indoor ventilation is urgently needed. So, this study places the purpose on validating volume of indoor ventilation and user's comfortable degree by comparison CO2 emission rate through changing floor temperature.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.8 no.4
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• pp.24-31
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• 2012

The Solar and geothermal energy have many advantage like low cost, non-toxic, and unlimited. But those the have very low energy efficiency. In this study, the theoretical study of performance in a sola-geothermal hybrid heat pump with operating conditions has carried out. As a result, as the solar radiation increases from 1 $MJ/m^2$ to 20 $MJ/m^2$, the heat pump operating time decreases by 19.5% from 18 times to 14.5 times and the heat pump heat decreases by 23%. Besides, the heating COP increases by 21.4% when the evaporator inlet temperature increases from $11^{\circ}C$ to $19^{\circ}C$. By adapting the geothermal system into a solar hybrid R22 heat pump, the system performance and reliability increases significantly for variable operating conditions during winter season.

• Korean Journal of Materials Research
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• v.22 no.6
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• pp.280-284
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• 2012

Bismuth antimony telluride (BiSbTe) thermoelectric materials were successfully prepared by a spark plasma sintering process. Crystalline BiSbTe ingots were crushed into small pieces and then attrition milled into fine powders of about 300 nm ~ 2${\mu}m$ size under argon gas. Spark plasma sintering was applied on the BiSbTe powders at 240, 320, and $380^{\circ}C$, respectively, under a pressure of 40 MPa in vacuum. The heating rate was $50^{\circ}C$/min and the holding time at the sintering temperature was 10 min. At all sintering temperatures, high density bulk BiSbTe was successfully obtained. The XRD patterns verify that all samples were well matched with the $Bi_{0.5}Sb_{1.5}Te_{3}$. Seebeck coefficient (S), electric conductivity (${\sigma}$) and thermal conductivity (k) were evaluated in a temperature range of $25{\sim}300^{\circ}C$. The thermoelectric properties of BiSbTe were evaluated by the thermoelectric figure of merit, ZT (ZT = $S^2{\sigma}T$/k). The grain size and electric conductivity of sintered BiSbTe increased as the sintering temperature increased but the thermal conductivity was similar at all sintering temperatures. Grain growth reduced the carrier concentration, because grain growth reduced the grain boundaries, which serve as acceptors. Meanwhile, the carrier mobility was greatly increased and the electric conductivity was also improved. Consequentially, the grains grew with increasing sintering temperature and the figure of merit was improved.