• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.157-164
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• 2008

The temperature-entropy diagram of water or vapor displays graphically the thermophysical properties, so it is very conveniently used in various thermal systems. On general T-s chart of water, there are temperature, pressure, quality, specific volume, specific enthalpy, specific entropy. However, various state and process values besides above properties can be plotted on T-s diagram. In this study, we developed the software drawing twenty six kinds of properties, that is temperature, pressure, quality, specific volume, specific internal energy, specific enthalpy, specific entropy, specific exergy, exergy ratio, density, isobaric specific heat, isochoric specific heat, ratio of specific heat, coefficient of viscosity, kinematic coefficient of viscosity, thermal conductivity, prandtl number, ion product, static dielectric constant, isentropic exponent, velocity of sound, joule-thomson coefficient, pressure coefficient, volumetric coefficient of expansion, isentropic compressibility, and isothermal compressibility. Also, this software can analyze and print the system values of mass flow rate, volume flow rate, internal energy flow rate, enthalpy flow rate, entropy flow rate, exergy flow rate, heat flow rate, power output, power efficiency, and reversible work. Additionally, this software support the functions such as MS-Power Point.

• The Journal of Korean Institute for Practical Engineering Education
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• v.3 no.1
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• pp.9-14
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• 2011

The expansion work that is wasted through the irreversible expansion through the PC valve of decompression process of the natural gas governor station can be recovered by replacing the process by an isentropic expansion. The energy and exergy analyses for the two decompression process models of power producing and current decompression process model are presented. Analysis results showed that the exergy by gas supply is 56.29%, the exergy by producing power is 32.12 % in case of preheating system and 22.52% in case of non-preheating system. The dead exergy at the PCV is generated much more network. As these results, the usefulness of exergy analysis is verified.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1200-1210
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• 1990

Conventional efficiencies of the adiabatic compression process such as isentropic efficiency and polytropic efficiency can be explained as exergetic efficiencies replacing the reference atmospheric temperature with the temperature which can be determined in the process itself. So that, other efficies such as maximum isentropic efficiency can be defined by giving proper reference temperatures. By applying the same logical principles, exergetic and other rational efficiencies for the non-adiabatic compression process are also defined and discussed for their physical meanings and reasonable engineering applications.

• Safety and Health at Work
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• v.7 no.2
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• pp.130-137
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• 2016

At a brewery, the base plate-to-shell weld seam of a $90-m^3$ vertical cylindrical steel tank failed catastrophically. The 4 ton tank "took off" like a rocket leaving its contents behind, and landed on a van, crushing it. The top of the tank reached a height of 30 m. The internal overpressure responsible for the failure was an estimated 60 kPa. A rupture disc rated at < 50 kPa provided overpressure protection and thus prevented the tank from being covered by the European Pressure Equipment Directive. This safeguard failed and it was later discovered that the rupture disc had been installed upside down. The organizational root cause of this incident may be a fundamental lack of appreciation of the hazards of large volumes of low-pressure compressed air or gas. A contributing factor may be that the standard piping and instrumentation diagram (P&ID) symbol for a rupture disc may confuse and lead to incorrect installation. Compressed air systems are ubiquitous. The medium is not toxic or flammable. Such systems however, when operated at "slight overpressure" can store a great deal of energy and thus constitute a hazard that ought to be addressed by safety managers.