• Tunnel and Underground Space
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• v.25 no.2
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• pp.115-124
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• 2015

Thermal energy storage (TES) is a technology that stores surplus thermal energy at high or low temperatures for later use when the customer needs it, not just when it is available. TES systems can help balance energy demand and supply and thus improve the overall efficiency of energy systems. Furthermore, the conversion and storage of intermittent renewable resources in the form of thermal energy can help increase the share of renewable resources in the energy mix which refers to the distribution of energy consumption from different sources, and to achieve this, it is essential to combine renewable resources with TES systems. Underground TES using rock caverns, known as cavern thermal energy storage (CTES), is a viable option for large-scale, long-term TES utilization although its applications are limited because of the high construction costs. Furthermore, the heat loss in CTES can significantly be reduced due to the heating of the surrounding rock occurred during long-term TES, which is a distinctive advantage over aboveground TES, in which the heat loss to the surroundings is significantly influenced by climate conditions. In this paper, we introduced important factors that should be considered in the shape and multiple layout design of TES caverns, and proposed guidelines for storage space design.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.1
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• pp.120-124
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• 2003

KAISTSAT- 4, an experimental small satellite, is being developd by Satellite Technology Research Center in KAIST as a sequel mission to KITSAT-1, 2, and 3. The flight model scheduled to be launched in 2003, the qualification model construction and testing have been completed recently. The satellite subsystems of the qualification model have been tested under a thermal vacuum environment harsher than expected in the orbit. Thermal balance test has also been done in order to evaluate and tune the thermal analysis model of the qualification model. This paper describes the thermal vacuum test procedure, the results, as well as the lessons learned during the tests, which can be useful for future thermal vacuum tests of small satellites.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.465-468
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• 1988

The output power is dependent of the vibrational level temperatures and wall temperature of the discharge tube in cw $CO_{2}$ lasers. The method postulates the introduction of a vibrational temperatures Ti for each vibrational mode. The vibrational and wall temperature are dertermined by the equations of the vibrational energy balance and thermal conductivity.

• Journal of Aerospace System Engineering
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• v.1 no.2
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• pp.37-42
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• 2007

This paper proposes a numerical modeling approach to simulate the hybrid combustion phenomena. From the physical understandings of hybrid combustion, the computational domain was separated into three regions: the solid fuel, gas phase reactive flow, and the interface between solid and fluid. Moreover, for the accurate calculation, computational grids for these regions was generated at every time step considering the instantaneous moving interface which are governed by the balance equations using thermal pyrolysis. In the domain of reactive flow, by virtue of diffusion flame structure, turbulent combustion modeling was introduced using either mixture fraction approach or mean reaction rate approach.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05d
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• pp.38-42
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• 2003

The use of VPI impregnated mica tape as high voltage insulation for large rotating electric machines requires a careful balance of processes and materials to obtain the desired electrical, mechanical and thermal characteristics. The stator insulation systems such as epoxy bonded high voltage mica tape have been produced for many years. One such system employing an epoxy and anhydride impregnating resin developed by Hyundai Heavy Industries, Co. (hereafter, HHI), to satisfy customer requests for an epoxy bonded insulation system. HHI applies the following electrical and thermal evaluations such as dielectric breakdown, voltage endurance, dissipation factor vs. temperature, isothermal weight loss, and so on. A detailed laboratory evaluation can describe specific physical limitations for an insulation system and permit development of long-term operation guidelines that permit full utilization of the proposed system. HHI has found these evaluations very helpful in qualifying insulation system for the repair of both large motors and generators.

• Architectural research
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• v.14 no.1
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• pp.11-18
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• 2012

College of Architecture, Georgia Institute of Technology, Atlanta, GA, US Abstract The intermittent heating and cooling energy need calculation of the ISO 13790 monthly method was examined. The current ISO 13790 method applies a reduction factor to the continuous heating and cooling need calculation result to derive the intermittent heating and cooling for each month. This paper proposes a method for the intermittent energy need calculation based on the internal mean temperature calculation. The internal temperature calculation procedure was introduced considering the heat-balance taking into account of heat gain, heat loss, and thermal inertia for reduced heating and cooling period. Then, the calculated internal mean temperature was used for the intermittent heating and cooling energy need calculation. The calculation results from the proposed method were compared to the current ISO 13790 method and validated with a dynamic simulation using EnergyPlus. The study indicates that the intermittent heating and cooling energy need calculation method using the proposed model improves transparency of the current ISO 13790 method and draws more rational outcomes in the monthly heating and cooling energy need calculation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.6
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• pp.553-563
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• 1984

Heat transfer modeling was performed in order to study a natural solar heating system. Simulation of the system was obtained by writing instantaneous energy balance equations for the various components. A thermal-network provided the means for systematically accounting for each of the energy balances. The resulting balances were solved using time varying inputs, such as solar gain and ambient temperature, and the initial temperatures of the components. Parametric heat transfer calculations were performed. Results are discussed which illustrate several effects, including variation of thermal capacity of the storage wall, installation of night insulation, installation of a thermally controlled fan between the sunspace and room, and variation of the width of the sunspace.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.600-601
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• 2010

This paper presents the superheater dynamic modeling and parameter estimation for the thermal plant boiler. The temperature control is closely related to the power plant efficiency and boiler life. The dynamic modeling of the superheater and desuperheater is essentially needed and developed by using the heat balance principle. The simulated model outputs are well matched with the actual ones. It is expected that the proposed model is useful for the temperature controller design.

• Journal of the Korean Society of Industry Convergence
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• v.2 no.2
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• pp.139-146
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• 1999

Combustion Characteristics of the wood chips(balsa chips) were experimental studied as fundamental investigation of the thermal recycle system of the urban dust. The urban dust contains plastics vegetable and lot of wood material. Then, a wood was chosen as an example of the component of urban dust. A small wood chip was burned in a electric furnace and mass reduction rate during volatile and combustion states were recorded by the micro-electric balance and the combustion flame shape took a photograph by video camera at the mass of wood chips and ambient temperature in the furance. Ignition delay took the minimum value when the mass of the test chip was 0.3g. When a mass of the test chip was smaller then 0.001g, combustion with flame did not burnt.

• Journal of the Korean Chemical Society
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• v.13 no.4
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• pp.309-312
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• 1969

A series of metal ion-2, 5-diamine 1, 4-dihydroxybenzene polymers containing copper(II), nickel(II) or cobalt (II) have been prepared. The structure was postulated on the basis of elementary analysis of polymers. It was found that copper polymer is most likely the coordination polymers by X-ray powder pattern studies. The thermal stability of the polymers was also studied by a simple method, utilizing a thermogravimetric balance. The order of thermal stabilities is Cu(II) > Ni(II) > Co(II). The polymers start to decompose at a relatively low temperature.