• Fashion & Textile Research Journal
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• v.11 no.3
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• pp.474-480
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• 2009

The purpose of this study is to prepare the hardness of polyester(PET) fabric by thermal bonding with low melting component of bicomponent fiber and to describe the change of physical properties of thermal bonded PET fabrics. The PET fabrics were prepared with regular PET fiber as warp and bicomponent fiber as weft. The bicomponent fiber of sheath-core type were composed with a regular PET core and low melting PET sheath. The thermal bonding of PET fabric was carried out in pin tenter from 120 to $195^{\circ}C$ temperature range for 60 seconds. In this study, we investigated the physical properties and melting behavior of PET fiber and the effect of the temperature of the pin tenter on the thermal bonding, mechanical properties. Melting peak of warp showed the thermal behavior of general PET fiber. However, melting peak of weft fiber(bicomponent fiber) showed the double melting peak. The thermal bonding of the PET fabric formed at about temperature of lower melting peak. The optimum thermal bonding conditions for PET fabrics was applied at $190{\sim}195^{\circ}C$ for 60seconds by pin tenter. On the other hand, the tensile strength of the PET fabric decreased with an increasing temperature of thermal bonding.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.1
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• pp.108-115
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• 2019

The thermal response of elastomeric insulators used as protection against high-temperature and high-pressure combustion gases varies depending on their composition and thermal environment conditions. In this paper, the thermal response characteristics of elastomeric insulators in different mixing environments were compared. Tests to determine thermal protection performance were carried out using a thermal protection rubber evaluation motor(TPREM), combustion gas velocities of 20 m/s and 100 m/s were tested at a chamber pressure of 1,000 psig. The pressure time curve of the chamber, the temperature time curve of the internal materials, the residual thickness and the thermal destruction depth of the test specimens were obtained. The results showed that the thermal protection performance of elastomeric insulators in different mixing environments was similar.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.171-174
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• 2005

The circuit simulation analysis and diagnosis methods are used to instruments in detail when they give apparently abnormal readings. In this paper, a new simulator through an analysis of the important circuits modeling under severe accident conditions has been designed, the realization for a body work instead of the two sorts of the Labview & Pspice as an one order command in the Labview program. The program can be shown the output graph form the circuit modeling as an order commend. The procedure for the simulator design was divided into two design steps, of which the first step was the diagnosis methods, the second step was the circuit simulator for the signal processing tool. It has three main functions which are a signal processing tool, an accident management tool, and an additional guide from the initial screen.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.701-704
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• 2005

Aquifer Thermal Energy Storage (ATES) can be a cost-effective and renewable geothermal energy source, depending on site-specific and thermohydraulic conditions. To design an effective ATES system having influenced by groundwater movement, understanding of thermo hydraulic processes is necessary. The heat transfer phenomena for an aquifer heat storage are simulated using FEFLOW with the scenario of heat pump operation with pumping and waste water reinjection in a two layered confined aquifer model. Temperature distribution of the aquifer model is generated, and hydraulic heads and temperature variations are monitored at the both wells during 365 days. The average groundwater velocities are determined with two hydraulic gradient sets according to boundary conditions, and the effect of groundwater flow are shown at the generated thermal distributions of three different depth slices. The generated temperature contour lines at the hydraulic gradient of 0.00 1 are shaped circular, and the center is moved less than 5m to the groundwater flow direction in 365 days simulation period. However at the hydraulic gradient of 0.01, the contour center of the temperature are moved to the end of boundary at each slice and the largest movement is at bottom slice. By the analysis of thermal interference data between two wells the efficiency of the heat pump system model is validated, and the variation of heads is monitored at injection, pumping and no operation mode.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.2
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• pp.150-157
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• 2008

The main objective of this paper is to investigate the performance characteristics of a $CO_2$ air conditioning system for fuel cell electric vehicles (FCEV). The present air conditioning system for FCEV uses the electrically driven compressor and electrically controlled expansion valve for $CO_2$ as a working fluid. The experimental work has been done with various operating conditions, which are quite matching the actual vehicle's driving conditions such as different compressor speed and high pressure to identify the characteristics of the system. Experimental results show that the cooling capacity and coefficient of performance (COP) were up to 6.3kW and 2.5, respectively. This paper also deals with the development of optimum high pressure control algorithm for the transcritical $CO_2$ cycle to achieve the maximum COP.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.1 s.244
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• pp.57-66
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• 2006

The experimental and the numerical study was performed on the comparison of thermal comfort(TC) and indoor air quality(IAQ) in the lecture room for cooling loads when the operating conditions are changed. PMV value and $CO_2$ concentration of the lecture room were measured and compared with the numerical results. The numerical results showed a good agreement with the experimental one and then the numerical tool was used to analyze thermal comfort and IAQ for a couple of operating conditions. As a result it was found that the increment of the discharge angle of system air-conditioner makes TC uniformity worse, but rarely affects IAQ. Also TC and IAQ were hardly affected by the variation of the discharge airflow. Finally it turned out that TC is merely affected by the increment of the ventilation airflow, but the average $CO_2$ concentration can be satisfied with Japanese IAQ standards of classrooms when the ventilation airflow is more than $800m^3/h$ in this study.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.4
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• pp.150-159
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• 2018

The present research deals with a finite element analysis and fatigue evaluation of a steam separator of a high-pressure evaporator for the Heat Recovery Steam Generator (HRSG). The fatigue during the expected life of the HRSG was evaluated according to the ASME Boiler and Pressure Vessel Code Section VIII Division 2 (ASME Code). First, based on the eight transient operating conditions prescribed for the HRSG, temperature distribution of the steam separator was analyzed by a transient thermal analysis. Results of the thermal analysis were used as a thermal load for the structural analysis and used to determine the mean cycle temperature. Next, a structural analysis for the transient conditions was carried out with the thermal load, steam pressure, and nozzle load. The maximum stress location was found to be the riser nozzle bore, and hence fatigue was evaluated at that location, as per ASME Code. As a result, the cumulative usage factor was calculated as 0.00072 (much less than 1). In conclusion, the steam separator was found to be safe from fatigue failure during the expected life.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.906-917
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• 1996

This study was conducted to find possible application areas of the by-products generated from the incineration of rice husk. To this end, a pilot-scale rice husk incinerator system was constructed and its performed test was carried. Major findings are summarized as follows. 1. The rice husk incinerator system developed in this study performed satisfactory in terms of thermal efficiencies. At the optimum operating conditions, thermal conversion efficiency and heat exchanger efficiency was 97% ad 60%, respectively, while overall thermal efficiency of the system was 58%. Under all conditions tested, temperatures in the combustion chamber were quite uniform and crystallization of SiO$_2$ in the ash was negligible. 2. NOx and SOx content in the flue gas was well below the legal limit but the CO concentration was around the legal limit. 3. Thermal energy from combustion was successfully recovered by a heat exchanger to provide hot water, ash was found a good supplementary cementing m terial, and the flue gas also was an acceptable $CO_2$ supplier to greenhouses.

• International Journal of Precision Engineering and Manufacturing
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• v.5 no.4
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• pp.5-13
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• 2004

This study explains the effects of lubricant and surface treatment on the life of hot forging dies. The thermal load and thermal softening, that occur when there is contact between the hotter billet and the cooler dies in hot forging, cause wear, thermal cracking and fatigue, and plastic deformation. Because the cooling effect and low friction are essential to the long life of dies, the proper selection of lubricant and surface treatment is very important in hot forging process. The two main factors that decide friction and heat transfer conditions are lubricant and surface treatment, which are directly related to friction factor and surface heat transfer coefficient. Experiments were performed for obtaining the friction factors and the surface heat transfer coefficients in different lubricants and surface treatments. For lubrication, oil-base and water-base graphite lubricants were used, and ion-nitride and carbon-nitride were used as surface treatment conditions. The methods for estimating die service life that are suggested in this study were applied to a finisher die during the hot forging of an automobile part. The new techniques developed in this study for estimating die service life can be used to develop more feasible ways to improve die service life in the hot forging process.

• KIEAE Journal
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• v.14 no.3
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• pp.97-103
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• 2014

This study aimed at developing integrated logic for controlling heating device and openings of the double skin facade buildings. Two major logics were developed-rule-based control logic and artificial neural network based control logic. The rule based logic represented the widely applied conventional method while the artificial neural network based logic meant the optimal method. Applying the optimal method, the predictive and adaptive controls were feasible for supplying the advanced thermal indoor environment. Comparative performance tests were conducted using the numerical computer simulation tools such as MATLAB (Matrix Laboratory) and TRNSYS (Transient Systems Simulation). Analysis on the test results in the test module revealed that the artificial neural network-based control logics provided more comfortable and stable temperature conditions based on the optimal control of the heating device and opening conditions of the double skin facades. However, the amount of heat supply to the indoor space by the optimal method was increased for the better thermal conditioning. The number of on/off moments of the heating device, on the other hand, was significantly reduced. Therefore, the optimal logic is expected to beneficial to create more comfortable thermal environment and to potentially prevent system degradation.