• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• 제15권9호
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• pp.744-750
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• 2003

The performance of adiabatic capillary tubes are measured to provide the database for a generalized correlation. Test conditions and capillary tube geometries are selected to cover a wide range typically observed in air-conditioning and heat pump applications. Based on extensive experimental data for R22, R290, and R407C measured in this study, a generalized correlation for refrigerant flow rate in adiabatic capillary tubes is developed by implementing dimensionless parameters for tube inlet conditions, capillary tube geometry, and refrigerant properties. The correlation yields good agreement with the present data for R22, R290, and R407C with average and standard deviations of 0.9% and 5.0%, respectively. In addition, approximately 97% of the data for Rl2, R134a, R152a, R410A, and R600a obtained in the open literature are correlated within a relative deviation of $\pm$ 15%.

• Transactions of the Korean Society of Automotive Engineers
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• 제7권5호
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• pp.107-120
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• 1999

Catalytic converters are the most fascinating and complicated chemical reactors. They are most often operated in the transient state with respect to composition, flow rate, temperature, etc. The mathermatical model developed in this work accounts for simultaneous heat and mass transfer, chemical reaction, and multi dimensional flow characteristics to analyze the light-off performance of monolithic catalytic converter with comparable mass flow rate. To validate the mathematical model, comparison between experimental and numerical results has been performed. The numerical results show a good agreement with experimental data. It is forund that inflow rate shows major effect on the characteristics of termal response of catalytic converter.

• Journal of the Korean Society for Heat Treatment
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• 제12권3호
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• pp.206-214
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• 1999

The effect of cooling rate on carbide precipitation during quenching of austenitic manganese steel was investigated by optical microscopy, image analyzer and numerical analysis. A computer program based on the finite difference method for analyzing heat treatment processes was developed in order to evaluate cooling rates and the possibility of carbide precipitation during quenching. The area ratio of carbide precipitated in the austenite matrix was measured by the image analyzer, and used to determine the critical point of carbide precipitation. Temperature-dependent critical cooling rates at the critical points were calculated using the present simulation program, The calculated results showed a good agreement with the experimental ones.

• Electrical & Electronic Materials
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• 제8권2호
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• pp.129-135
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• 1995

SiO thin films are deposited by evaporator the refractive index of wave length, photon energy and the absorptive rate of these films are measured by spectroscopic ellipsometer. It is derived the absorptive rate and permitivity of SiO thin films from the equations that calculating the refractive index. And the result show good agreement with the calculated values and experimental values. As a result, the wave length of light is increased in the condition that the angle of incidence is fixed on SiO thin film, the basic absorption and the absorption impurities are found in the low wave length (below 450 nm in this study) and the reflective absorption and conductive absorption is increased by the form of exponential function over the low wavelength. The absorptive rate is increased by increased the angle of incidence and thickness of SiO film for the insulating layer. As the thickness of SiO film is increased, the value of complex permitivity is decreasing and as wave length of incidence is increased., the value of dielectric is linearly increasing.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.748-753
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• 2004

The performance of a valveless micropump driven by chamber wall oscillation was numerically investigated for various frequency and amplitude of the oscillation. The numerical study was performed in the range of oscillation frequency from 200Hz to 1000Hz and amplitude from $1{\mu}m$ to $15{\mu}m$. And optimal values for the parameters are found. At the oscillation frequency 600Hz, the net flow rate of micropump shows a maximum value. Also the results show good agreement with the experimental results. The total flow rate was increased with the oscillation amplitude. However, the net flow rate was found to be decreased over $7{\mu}m$.

• Nuclear Engineering and Technology
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• 제30권5호
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• pp.424-434
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• 1998

RELAP5/Mod3.1 code was assessed with the semiscale experiment S-NC-3, and S-NC-4, which simulated the two-phase natural circulation and reflux condensation for the SBLOCA of PWR, respectively . Test S-NC-3 and S-NC-4 calculation results showed that RELAP5/Mod3.1 quite well describes the influence of steam generator secondary side heat transfer degradation on both two-phase natural circulation and reflux condensation. A comparison between the calculated and measured two-phase mass flow rate in test S-NC-3 shows good agreement for primary mass inventory more than 92%. And RELAP5/Mod3.1 have a good mass flow rate prediction capability for the transient such as S-NC-4 except some flow oscillations. The reflux flow rate for S-NC-4 test is under predicted, and the overall results verify that the correct prediction of the reduced liquid level appears to be required for the correct calculation of the overall phenomena.

• Nuclear Engineering and Technology
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• 제48권5호
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• pp.1252-1263
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• 2016

This paper presents a numerical method to simulate ductile tearing in cracked components under high strain rates using finite element damage analysis. The strain rate dependence on tensile properties and multiaxial fracture strain is characterized by the model developed by Johnson and Cook. The damage model is then defined based on the ductility exhaustion concept using the strain rate dependent multiaxial fracture strain concept. The proposed model is applied to simulate previously published three cracked pipe bending test results under two different test speed conditions. Simulated results show overall good agreement with experimental results.

• Transactions of Materials Processing
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• 제18권1호
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• pp.80-86
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• 2009

This paper presents the plastic inhomogeneous deformation behavior of bimetal composite rods during the axisymmetric and steady-state extrusion process through a conical die. The rigid-plastic FE model considering frictional contact problem was used to analyze the co-extrusion process with material combinations of Cu/Al. Different cases of initial geometry shape for composite material were simulated under different conditions of co-extrusion process, which includes the interference and frictional conditions. From the simulation results, the sleeve cladding rate at the core/sleeve interface was recorded as a distribution of diameter ratio and interference conditions, which will be useful for the investigations of the bonding process during co-extrusion process. In addition, the results of the co-extrusion, connected with the results of the variations of diameter rate and average contact pressure, demonstrate a good agreement and present the possibility of describing the parameters of the plastic zones in non-uniform deformation of these type of composite materials.

• Journal of Environmental Health Sciences
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• 제35권6호
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• pp.532-537
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• 2009

The tropospheric ozone production mechanism for the gas phase additive oxidation reaction of hydroxyl radical (OH) with isoprene (2-methyl-1,3-butadiene) has been studied using cavity ring-down spectroscopy (CRDS) at total pressure of 50 Torr and 298 K. The applicability of CRDS was confirmed by monitoring the shorter (~4%) ringdown time in the presence of hydroxyl radical than the ring-down time without the photolysis of hydrogen peroxide. The reaction rate constant, $(9.8{\pm}0.1){\times}10^{-11}molecule^{-1}cm^3s^{-1}$, for the addition of OH to isoprene is in good agreement with previous studies. In the presence of $O_2$ and NO, hydroxyl radical cycling has been monitored and the simulation using the recommended elementary reaction rate constants as the basis to OH cycling curve gives reasonable fit to the data.

• Proceedings of the KSME Conference
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1481-1486
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• 2004

This report presents experimental results on the heat transfer coefficients in the boiling region of spray cooling for actual metallurgical process. In this study, the heat flux distribution of a two dimensional dilute spray impinging on hot plate was experimentally investigated. Based on the experimental results, they classified the heat transfer area into the stagnation region and wall-flow region. In the stagnation region, the local heat transfer coefficient relates mainly to the droplet-flow-rate supplied from spray nozzle directly, so the local heat transfer coefficients is good agreement with the predicted values from correlation for spray cooling proposed by former report However, the local heat transfer coefficient in wall-flow region is larger than predicted values, and it is found that the rebounding droplets-flow-rate must be accurately evaluated to predict the local heat transfer coefficient in this region.