• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.239-240
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• 2022

In winter, low outdoor temperature can casue reduction of concrete strength. Therefore, thermal protection is required when curing concrete in winter to maintain a certain level or higher surface temperature. Accordingly, in domestic construction sites, a curing method in which surrounds casting areas by tents and operates hot air blowers are widely applied. However, local low-temperature areas may occur due to airtightness of the curing tents. If additional heat is supplied to prevent occurrence of local low-temperature areas, energy consumption increases. Therefore in this study, a plan for improvement method of concrete curing was considered and the performance was evaluated through numerical analysis. A plan to improve the airtightness of the wall opening was applied, but the analysis showed that if only a part of the curing area is shielded, the temperature of the unshielded area decreases,making it inappropriate to improve curing performance.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.11
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• pp.1008-1015
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• 2015

Thermal vacuum test should be performed prior to launch to verify satellites' functionality in extremely cold/hot temperatures and vacuum conditions. A thermal vacuum chamber used to perform the thermal vacuum tests of a satellite system and its components. A cryogenic blower is a core component of the gaseous nitrogen (GN2) closed loop thermal control system for thermal vacuum chambers. A final goal of this research is development of cryogenic blower. Design requirements of a blower are 150 CFM flow rate, 0.5 bara pressure difference, hot and cold temperatures. This paper describes the performance analysis of impeller by 1D, CFD commercial software, the design of the thermal protection interface between the driving part and the fluid part. The performance of the cryogenic blower is confirmed by test at the standard air condition and is verified by on the thermal vacuum chamber at the real operating condition.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.6
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• pp.365-371
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• 2008

Condensing gas boiler units may make a big role for the reduction of energy consumption in heating industries. In order to decrease the energy consumption of a condensing gas boiler unit, effective operations of the system are necessary. In this study, mathematical models of a condensing gas boiler system were developed in order to develop control algorithms of the system. These include dynamic models of a blower, a gas valve, a pump, a burner, a boiler heat exchanger, and a hot water heat exchanger. Control algorithms of a blower, a gas valve, and a pump were also assumed. Simulation results showed good predictions of dynamic behaviors of a boiler system. Therefore, the simulation program developed for this study may be effectively used for the development of control algorithms of a boiler system.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11c
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• pp.654-661
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• 2000

Area of greenhouse increases rapidly up to 45,265ha by the year of 1998 in Korea. Hot air heater with light oil combustion is the most common heater for greenhouse heating in the winter season. However, exhaust gas heat discharged to atmosphere through chimney reaches up to 10~20% of total heat of the oil combusted in the furnace. In order to recapture the heat of this exhaust gas and to recycle for greenhouse heating, the heat pipe type exhaust heat recovery system was manufactured and tested in this experiment. The exhaust heat recovery system was made for space heating in the greenhouse. The system consisted of a heat exchanger made of heat pipes, ${\emptyset}15.88{\times}600mm$ located in the rectangular box of $600{\times}550{\times}330mm$, a blower and air ducts. The rectangular box was divided by two compartments where hot chamber exposed to exhaust gas in which heat pipes could pick up the heat of exhaust gas, and by evaporation of the heat transfer medium in the pipes it carries the heat to the cold compartment, then the blower moves the heat to greenhouse. The number of heat pipe was 60, calculated considering the heat exchange amount between flue gas and heat transfer capacity of heat pipe. The working fluid of heat pipe was acetone because acetone is known for its excellent heat transfer capacity. The system was attached to the exhaust gas path. According to the performance test it could recover 53,809 to 74,613kJ/hr depending on the inlet air temperature of 12 to $-12^{circ}C$ respectively when air flow rate $1,100\textrm{m}^3/hr$. The exhaust gas temperature left the heat exchanger dropped to $100^{circ}C$ from $270^{circ}C$ by the heat exchange between the air and the flue gas, the temperature difference was collected by the air and the warm air temperature was about $60^{circ}C$ at the air flow rate of $1,100\textrm{m}^3/hr$. This heat pipe type exhaust heat recovery system can reduce fuel cost by 10% annually according to the economic analysis.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.3
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• pp.58-67
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• 2006

In this paper, fuzzy logic based active ventilation system with security function is proposed and implemented. We can easily experience the situation that inner air is so hot to get start immediately after parking at summer day. Hot temperature is enough to explode a gas lighter or to suffocate a little chid. Proposed system has 1 blower and 2 axial fans to ventilate inner air. Based on the fuzzy logic, speed and direction of each fan are controlled. In addition to controlling fans, controller put down windows and adjust the periods of open time. In order to prevent the theft and security problems, IR sensors are used to detect objects. On detecting objects, controller put up windows. Experimental result shows that implemented system can be effectively ventilate inner air and reduce temperature. Proposed system can be applicable to commercial automobiles.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.34-39
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• 2007

Condensing gas boiler units may make a big role for the reduction of energy consumption in heating industries. In order to decrease the energy consumption of a condensing gas boiler unit, the effective operations and controls of the system are necessary. In this study, mathematical models of a condensing gas boiler system were developed and programmed in order to predict dynamic behaviors of the system. These include dynamic models for a blower, a gas valve, a pump, a burner, a boiler heat exchanger, and a hot water heat exchanger. Control algorithms for the control of a gas valve, a blower, and a pump were also assumed. Simulation results showed good predictions of the dynamic phenomena of a boiler system. Therefore, the simulation program developed for this study may be effectively used for the development of control algorithms of the boiler system.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.10a
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• pp.150-160
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• 1998

Measuring temperature with ultrasonic wave apparatus is desirable in the case of both below 300$0^{\circ}C$ and ideal gas because of the fact that the temperature of gas is the function of only sound velocity. In this study, being used a heatable wind channel and a blower, the variation of temperature is observed in accordance with diverse flow rate(air velocity). The frequency modulation method is used to measure the temperature which is varying in hot air flow till 10$0^{\circ}C$. The length changed in the position of ultrasonic sensors is considered. Also, the effects of air velocity at the same temperature and various facing angles of ultrasonic sensors are considered. As a result of this study, it has been found that the temperature in gas flow is correctly measured regardless of both the distance of ultrasonic sensors and the variation of air velocity, and that there is just a little influence of facing angles.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.7
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• pp.893-900
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• 1999

Measuring temperature with ultrasonic wave apparatus is desirable in the cue of gas below $300^{\circ}$ because of the fact that the temperature of gas is the function of only sound velocity. In this study, being used a heatable wind channel and a blower. the variation of temperature is observed in accordance with flow rate(air velocity). The frequency modulation method is used to measure the temperature which is varying in hot air flow up to $100^{\circ}$. The length changed in the position of ultrasonic sensors is considered. Also. the effects of air velocity at the same temperature and various facing angles of ultrasonic sensors are considered. As a result of this study. it has been found that the temperature in gas flow is correctly measured regardless of both the distance of ultrasonic sensors and the variation of air velocity. and that there is just a little influence of facing angles.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.460-463
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• 2008

A large part of the overall industrial energy is dissipated as waste heat despite of much development in the utilization of thermal energy. A mean efficiency is reported to be only around 30 to 35%. The existing waste heat recovery technology has reached its limit and consequently, the development of a new technology is necessary. Improving efficiency using thermoelectric technology has recently come into the spotlight because of its unique way to recover thermal energy. In fact, thermoelectric generator directly converts thermal energy into electric energy by a solid state without any moving parts. Futhermore remarkable improvement in the thermoelectric energy conversion efficiency has been achieved. In this study, a thermoelectric generator was made using commercialized thermoelectric modules. With thermoelectric modules attached on a duct surface, hot air was blown into the duct using a hot air blower. On the other side of the module, a water jacket was attached to cool the module. With different air inlet temperatures and water flowrates, the electrical power of the thermoelectric generator was measured.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.140-141
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• 2022

CFD analysis was performed to analyze the temperature distribution of the inner space of the curing house according to blocking the opening of the gang-form with a tent in case of concrete pouring and heat curing of the apartment house during the winter season. If the gang-form opening is closed with a tent during internal heating using a hot air blower in the winter, the internal temperature rises compared to the non-reserved due to air-tightness of the curing spaces, and uniform temperature distribution can be ensured. In addition, it is possible to increase curing efficiency by reducing the amount of heat supplied and shortening the heating time.