• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.3
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• pp.302-307
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• 2017

An electric steam boiler equipped with a condensate recovery system, which stores the condensate generated after using steam in steam washers, steam cookers, steam irons, and steam cleaners in a condensate tank and supplies compressed air to the condensate tank so that the condensate is recovered to the boiler by the pressure of the compressed air, was studied. In the results of this study, the heat energy balance between the quantity of the heat generated by the non-metallic surface heating element and the quantity of the heat absorbed by the water was good in a range of ${\pm}5%$. In addition, the heat transfer rate increased in proportion to the electric power of the surface heating element heater, the waste heat energy was normally recovered by the recovery of the condensate of the steam boiler equipped with the high compression waste heat recovery system, and the recovery rate of the waste heat exhibited 23%.

• Nuclear Engineering and Technology
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• v.53 no.8
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• pp.2427-2444
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• 2021

The lack of plant-side energy storage analysis to support nuclear power plants (NPP), has setup this research endeavor to understand the characteristics and role of specific storage technologies and the integration to an NPP. The paper provides a qualitative review of a wide range of configurations for integrating the energy storage system (ESS) to an operating NPP with pressurized water reactor (PWR). The role of ESS technologies most suitable for large-scale storage are evaluated, including thermal energy storage, compressed gas energy storage, and liquid air energy storage. The methods of integration to the NPP steam cycle are introduced and categorized as electrical, mechanical, and thermal, with a review on developments in the integration of ESS with an operating PWR. By adopting simplified off-design modeling for the steam turbines and heat exchangers, the results show the performance of the PWR steam cycle changes with respect to steam bypass rate for thermal and mechanical storage integration options. Analysis of the integrated system characteristics of proposed concepts for three different ESS suggests that certain storage technologies could support steady operation of an NPP. After having reviewed what have been accomplished through the years, the research team presents a list of possible future works.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.1
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• pp.33-40
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• 2014

Air compressor is an important facility with electric power in the industry. However, because of the noise and vibration of air compressor and is installed outside the building management difficulty. In this study, MCP (Micro Control Processor) to remote monitoring of the air compressor via the compressed air through improved quality and allows stable maintenance were designed. So, increase the productivity improvement of energy-saving effect can be obtained. Remote real-time information stored on your PC to manage air compressor equipment was higher reliability. Monitoring system is developed in this study was applied to embedded systems. It is easy to install air compressor, and low maintenance costs was to raise the economic impact.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.6
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• pp.70-75
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• 2010

Compressed air represents an energy source and an force-transmission medium for brake systems on medium-heavy and heavy-duty commercial vehicles. However, one disadvantage is the tendency of air to absorb moisture in the form of water vapor. This water vapor condenses once the air, which is heated during compression, cools back to ambient temperature upon emerging from the air compressor. The resulting condensation assumes the form of moisture in pneumatic lines, air tanks, cylinders and valve assemblies and can have negative consequences for the brake system and vehicle safety. The pneumatic systems on today's vehicles are equipped with air dryers, in which the supplied air is dried according to the adsorption principle. In the systems, the compressed air flows through a granular desiccant with molecular sieves which captures the water molecules.

• Journal of Power System Engineering
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• v.15 no.6
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• pp.95-100
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• 2011

In this study, an evaluation equation of energy efficiency of pneumatic driving apparatus is proposed. The evaluation equation is derived from state equation and energy equation of air in a control volume, and, the equation of motion of a moving part of a pneumatic cylinder. As a result, distribution of consumption energy and energy efficiency of pneumatic driving apparatus can be analyzed quantitatively. The effectiveness of the proposed method is proved by a pneumatic cylinder driving apparatus using a meter-out driving method.

• Tunnel and Underground Space
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• v.10 no.2
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• pp.249-256
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• 2000

According to the industrial restructuring in the late 1980's, most domestic mines have been shutdown or suspended in operation. The closed underground excavation caverns remain in their abandoned conditions, and they will potentially cause environmental hazards. To evaluate the feasibility of the utilization of the abandoned caverns, the foreign crises were studied. As a result, we proposed several possible examples including underground storage cavern fur food products, underground compressed air energy system(CAES), and underground repository (or incineration plant) of industrial wastes. Among them, the underground waste repositories are most probable to be seen in Korea in the near future. For this, the study in rock engineering aspects should be conducted, which will include the establishment of support system and safety measure of the abandoned underground excavation caverns.

• Tribology and Lubricants
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• v.21 no.3
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• pp.114-121
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• 2005

As fuel cell system is environmental friendly generator, its performance depends on its air supply system. Because, fuel cell stack generates electrical energy by electron and the electron is generated by reacting between air and hydrogen. So, more and more compressed air is supplied, more and more the energy can be obtained. In this study, turbo-expander supported by air foil bearing is introduced as the air supply system used by fuel cell systems. The turbo-expander is a turbo machine which operates at high speed, so air foil bearings suit its purpose for the bearing elements. Analysis for confirming the stability and endurance is conducted. Based on FDM and Newton-Raphson method, characteristics of air foil bearing, dynamic coefficients, pressure field and load capacity, are obtained. Using the characteristics of air foil bearing, the rotordynamic analysis is performed by finite element method. The analysis (stability analysis and critical speed map) shows that turbo-expander is stability at running speed. After the analysis, the test process and results are presented. The goals of test are running up to 90,000 RPM, flow rate of 150 $m^3/h$ and pressure ratio of 1.15. The test results show that the aerodynamic performance and stability of turbo-expander are satisfied to the primary goals.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.918-921
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• 2001

In grinding process, the heat of $1200^{\circ}$~$1500^{\circ}$ on the grinding area between grinding wheel and workpiece is generated. It decreases the surface integrity of workpiece and causes the thermal damages such as the deformed layer, residual stress and grinding burn. Generally coolant is widely used for preventing the heat generation on the grinding area, but it deteriorates the working condition by polluting the atmosphere of workplace and in the end pollutes the environment. The grinding methods using the compressed cold air and mist are the cooling methods to substitute conventional coolant. They can decrease the environmental pollution through not using coolant any more or minimizing it. In this study, the cooling effects of grinding methods using the compressed cold air and mist have been investigated. The grinding system equipped with the water bathe and mist spray nozzle was developed. The energy partition to workpiece through measuring the temperature on the workpiece surface was calculated. The surface integrity of workpiece and thermal damage like the deformed layer were analyzed.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.197-200
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• 2007

FCEV uses electric energy generated from fuel cell stack, thus all consisting parts must be re-designed to be suitable for electricity based system. Cathode air blower which supplies compressed air into fuel cell stack has similar shape of turbocharger, but a radial turbine of traditional turbocharger is removed and high speed BLDC motor is installed . Generally, maximum 10% of electric power of fuel cell stack is consumed in air blower, therefore an effective design of air blower can improve the performance of FCEV directly. This study will present an aerodynamic design process of an air blower and compare computational results with experimental data.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.7
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• pp.417-427
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• 2014

Renewable energy sources such as solar, wind and hydro provides utilizing renewable power and reduce the using fossil fuels. On the other hand, it is too critical to apply power system due to the intermittent nature of renewable energy sources, the continuous fluctuations of the power load, and the storage with high energy density. Energy storage system, including pumped-hydroelectric energy storage, compressed-air energy storage, superconducting magnetic energy storage, and electrochemical devices like batteries, supercapacitors and others have shown that solve some of the challenges. In this paper, we review the current state of applications of energy storage systems, and atomic layer deposition technology, graphene materials on the energy storage systems and processes.