• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.225-228
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• 2012

Thermodynamic and economic analysis on various type of gas turbine combined cycle power plants was presented to build up the criteria for optimization of power plants. The efficiency considered about energy level difference between electricity and heat was introduced. The efficiency on power and heat generation of power plants whose have different purpose was estimated and power generation costs on various type of combined heat and power plants : fired/unfired, condensing/non-condensing mode, single/double pressure HRSG.

• Korean Chemical Engineering Research
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• v.62 no.2
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• pp.173-180
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• 2024

Under ordinary atmospheric circumstances, the gravimetric technique was used to measure the solubility of L-cysteine (L-Cys) and L-alanine (L-Ala) in various solvents, including methyl alcohol, ethyl acetate, and mixtures of the two, in the range o 283.15 K to 323.15 K. Both individual solvents and their combinations showed a rise in the solubility of L-Cys and L-Ala with increasing temperature, according to the analyzed data but when analyzed at a constant temperature in the selected mixed solvents, the solubility declined with decreasing of initial mole fractions of methyl alcohol. To further assess, the relative utility of the four solubility models, we fitted the solubility data using the Jouyban-Acree (J-A), van't Hoff-Jouyban-Acree (V-J-A), Apelblat-Jouyban-Acree (A-J-A), and Ma models followed by evaluation of the values of the RAD information criteria and the RMSD were. The dissolution was also found to be an entropy-driven spontaneous mixing process in the solvents since the thermodynamic parameters of the solvents were determined using the van't Hoff model. In order to support the industrial crystallization of L-cysteine and L-alanine and contribute to future theoretical research, we have determined the experimental solubility, correlation equations, and thermodynamic parameters of the selected amino acids during the dissolution process.

• Atmosphere
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• v.24 no.4
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• pp.457-470
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• 2014

Thermodynamic conditions related with localized torrential rainfall in the middle west region of Korean peninsula are examined using radar rain rate and radiosonde observational data. Localized torrential rainfall events in this study are defined by three criteria base on 1) any one of Automated Synoptic Observing System (ASOS) hourly rainfall exceeds $30mmhr^{-1}$ around Osan, 2) the rain (> $1mmhr^{-1}$) area estimated from radar reflectivity is less than $20,000km^2$, and 3) the rain (> $10mmhr^{-1}$) cell is detected clearly and duration is short than 24 hr. As a result, 13 cases were selected during the summer season of 10 years (2004-13). It was found that the duration, the maximum rain area, and the maximum volumetric rain rate of convective cells (> $30mmhr^{-1}$) are less than 9hr, smaller than $1,000km^2$, and $15,000{\sim}60,000m^3s^{-1}$ in these cases. And a majority of cases shows the following thermodynamic characteristics: 1) Convective Available Potential Energy (CAPE) > $800Jkg^{-1}$, 2) Convective Inhibition (CIN) < $40Jkg^{-1}$, 3) Total Precipitable Water (TPW) ${\approx}$ 55 mm, and 4) Storm Relative Helicity (SRH) < $120m^2s^{-2}$. These cases mostly occurred in the afternoon. These thermodynamic conditions indicated that these cases were caused by strong atmospheric instability, lifting to overcome CIN, and sufficient moisture. The localized torrential rainfall occurred with deep moisture convection result from the instability caused by convective heating.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.2
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• pp.223-231
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• 2011

The thermal efficiency of energy-to-power conversion becomes uneconomically low when the temperature of heat source drops below $370^{\circ}C$. ORC (Organic Rankine Cycle) has attracted much attention in last few years due to its potential in reducing consumption of fossil fuels and relaxing environmental problems, and its favorable characteristics to exploit low-temperature heat sources. In this work thermodynamic performance of ORC using nine working fluids is comparatively assessed. Special attention is paid to the effect of system parameters such as turbine inlet temperature and pressure on the characteristics of the system such as volumetric flow rate and quality at turbine exit, latent heat, net work as well as thermal efficiency. Results show that in selection of working fluid it is required to consider various criteria of performance characteristics as well as the thermal efficiency. Results also show that the system efficiencies become same irrespective of kind of working fluid when the temperature of heat source decreases to low range.

• Journal of the Korean Society of Combustion
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• v.18 no.3
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• pp.1-8
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• 2013

Thermodynamic and economic analyses of various types of gas turbine combined cycle power plants have been performed to establish criteria for optimization of power plants. The concept of efficiency, in terms of the difference in energy levels of electricity and heat, was introduced. The efficiency of power and heat generation by power plants with other purposes was estimated, and power generation costs were figured out for various types of combined heat and power plants(i.e., fired and unfired, condensing and non-condensing modes, single or double pressure HRSG).

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.15-17
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• 2013

In the design of combined cycle power plants, the design parameters considered mainly could be changed and added for performance evaluation with change on the design objective and method. Therefore, the design criteria considering the different objectives and type of power plant were needed. Thermodynamic and economic analyses of various types of gas turbine combined cycle power plants with demand on generation of power and heat and carbon capture system from high pressure flue gas have been performed to establish criteria for optimization of power plants.

• Biotechnology and Bioprocess Engineering:BBE
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• v.1 no.1
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• pp.26-31
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• 1996

Since biosynthesis of lignin peroxidase from Phanerochaete chrysosporium was known to be sensitive to shear, it is interesting to understand the effects of the shear sensitivity for the overproduction of lignin peroxidase. In stirred-tank fermentor, the shear-sensitivity in lignin peroxidase biosynthesis was quantified by using Kolmogorov length scale. It was found that agitation at 80$\mu$m Kolmogorov length scale is advantageous for the production of lignin peroxidase from P. chrysosporium. To overcome the shear sensitivity in lignin peroxidase biosynthesis caused by the agitation,P. chrysosporium was immobilized on various solid carriers. The nylon-immobilized P. chrysosporium was chosen in the present study as a way to overcome the shear sensitivity at the ranges of above 50$\mu$m Kolmogorov length scale. The adhesion force between immobilized cell and carrier can be predicted by thermodynamic approach and used as a criteria to select an adequate carrier materials for immobilization.

• Journal of Industrial Technology
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• v.21 no.B
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• pp.31-35
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• 2001

The phase forming ability and formation enthalpies(${\Delta}H$) of Si-M(M = Ti, Cu, Ni, Zr) compound alloys were predicted by Miedema's model. The silicon compound alloys were synthesized by mechanical alloying and then characterized for the phase formation by X -ray diffraction. The electrochemical properties as the anode materials for lithium ion batteries were investigated using a galvanostatic method. It appears that the electrochemical characteristics of Si-M alloys can be predicted from the thermodynamic criteria for the phase formation using the Miedema's model.

• Korean Chemical Engineering Research
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• v.55 no.1
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• pp.130-134
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• 2017

Organic aerosols dispersed in the atmosphere likely undergo phase separation. Such internally mixed particles are often described as comprising an organic phase and an aqueous phase separately. We studied the morphology of two liquid separated aerosols in the sub-microscale by using a simple thermodynamic model with Russian doll geometry. The morphology of particles can be easily predicted from the simple criteria on the surface tension and two algebraic equations (the volume constraint and Young equation). This result may give the potential explanation about the complex morphology of the organic airborne particles.

• Polymer(Korea)
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• v.25 no.4
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• pp.536-544
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• 2001

We investigate, in the viewpoint of mathematical stability, the validity of the time-strain separability hypothesis employed in polymer viscoelasticity on the basis of experimental results. There have been suggested two distinct stability criteria such as Hadamard related to quick response and dissipative stability conditions, and in the limit of high deformation rate we have proved that separable constitutive equations are either Hadamard or dissipative unstable. The fact that the separability is not valid in the short time region in stress relaxation experiments exactly coincides with the results of our analysis. Therefore, since the application of the separability hypothesis incurs thermodynamic inconsistency as well as mathematical instability, such application should be avoided in the formulation of constitutive equations. In addition, careful attention should be paid to the limit of its validity even in experiments. It is also proved that there is neither theoretical nor physical validity of using the damping function.