• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.1
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• pp.172-181
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• 1993

Pseudo-Brayton cycle is defined as an ideal Brayton cycle admitting the difference between heat capacities of working fluid during heating and cooling processes. The endo-pseudo-Brayton cycle which is a pseudo-Brayton cycle with heat transfer processes is analyzed with the consideration of maximum power conditions and the results were compared with those of the endo-Carnot cycle and endo-Brayton cycle. As results, the maximum power is an extremum with respect to the cycle temperature and the flow heat capacities of heating and cooling processes. At the maximum power condition, the heat capacity of the cold side is smaller than that of heat sink flow. And the heat capacity of endo-Brayton cycle is always between those of heat source and sink flows and those of the working fluids of pseudo-Brayton cycle. There is another optimization problem to decide the distribution of heat transfer capacity to the hot and cold side heat exchangers. The ratios of the capacies of the endo-Brayton and the endo-pseudo-Braton cycles at the maximum power condition are just unity. With the same heat source and sink flows and with the same total heat transfer caqpacities, the maximum power output of the Carnot cycle is the least as expected, but the differences among them were small if the heat transfer capacity is not so large. The thermal efficiencies of the endo-Brayton and endo-Carnot cycle were proved to be 1-.root.(T$_{7}$/T$_{1}$) but it is not applicable to the pseudo-Brayton case, instead it depends on comparative sizes of heat capacities of the heat source and sink flow.w.

• Proceedings of the KWS Conference
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• 2003.05a
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• pp.48-51
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• 2003

No Abstract, See Full Text

• Proceedings of the Korean Nuclear Society Conference
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• 2004.05a
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• pp.450-450
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• 2004

• Proceedings of the Korean Nuclear Society Conference
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• 2003.10a
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• pp.216-216
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• 2003

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2000.11a
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• pp.28-29
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• 2000

• Proceedings of the Korean Nuclear Society Conference
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• 1999.10a
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• pp.75.2-75
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• 1999

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.615-620
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• 2010

During braking of railway vehicles the repetitive thermal shock leads to thermal cracks on disc surface, and the lifetime of brake disc is dependent on the number of trimming works for removing these thermal cracks. Many tries for development of high heat resistant brake disc to extend the disc life and to warrant reliable braking performance has been continued. In present study, we carry out the computational fatigue analysis for thermal fatigue test in three candidate materials which were made to develop new high heat resistant material. Using FEM, we simulate thermal fatigue test in three candidate materials and conventional disc material. We then estimate the number of cycle to thermal crack initiation based on data from mechanical fatigue tests, and the results are compared with each material. For each material, the correction factor for $N_{f-40}$ which is the number of cycles when crack over $40{\mu}m$ was observed in thermal fatigue test is decided. From this study, we can verify the performance of thermal fatigue test system and suggest a qualitatively comparative method for heat resistance by FEM analysis of thermal shocking phenomenon.

• Journal of the Korean Institute of Telematics and Electronics
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• v.6 no.3
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• pp.1-7
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• 1969

The Series RC load is connected with the word line in an attempt to select with high speed the information from the coincident current magnetie memory core. By taking the small time constant of the RC load, the cycle time of the output pulse is shortened by about 2 microseconds to 3 micro seconds. For this purpose, the analytical study are accomplished and the optimum circuit parameters are determined. Furthermore, the thermal problems occuring from the high speed switching of the magnetic memory core have been clarified.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.581-585
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• 2009

In this study, conceptual design of the RBCC (Rocket Based Combined Cycle) engine was performed for the hypersonic propulsion system development. For the flight mission, RBCC engine takes off at sea level and accelerates up to Mach 8 at the altitude of 30km. By the flight speed characteristics, operating pattern of the engine is categorized into 3 modes : Ejector jet (~Mach 3), Ramjet (Mach 3~6), Scramjet (Mach 6~8). According to the engine mode characteristics, RBCC engine design and analysis was performed.

• Journal of Energy Engineering
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• v.19 no.1
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• pp.32-38
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• 2010

The objective of the research was to study the effects a Miller cycle. The engine was dedicated to natural gas usage by modifying pistons, fuel system and ignition systems. The engine was installed on a dynamometer and attached with various sensors and controllers. Intake valve timing, engine speed, load, injection timing and ignition timing are main parameters. Miller Cycle without supercharging can increase brake thermal efficiency 1.08% and reduce brake specific fuel consumption 4.58%. The injection timing must be synchronous with valve timing, speed and load to control the performances, emissions and knock margin. Throughout these tested speeds, original camshaft is recommended to obtain high volumetric efficiency.