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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers B
Journal Basic Information
Journal DOI :
The Korean Society of Mechanical Engineers
Editor in Chief :
Volume & Issues
Volume 27, Issue 12 - Dec 2003
Volume 27, Issue 11 - Nov 2003
Volume 27, Issue 10 - Oct 2003
Volume 27, Issue 9 - Sep 2003
Volume 27, Issue 8 - Aug 2003
Volume 27, Issue 7 - Jul 2003
Volume 27, Issue 6 - Jun 2003
Volume 27, Issue 5 - May 2003
Volume 27, Issue 4 - Apr 2003
Volume 27, Issue 3 - Mar 2003
Volume 27, Issue 2 - Feb 2003
Volume 27, Issue 1 - Jan 2003
Selecting the target year
Cross Sectional Thermal and Electric Potential Imaging of an Operating MOSFET
Kwon, Oh-Myoung ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 829~836
DOI : 10.3795/KSME-B.2003.27.7.829
Understanding of heat generation in semiconductor devices is important in the thermal management of integrated circuits and in the analysis of the device physics. Scanning thermal microscope was used to measure the temperature and the electric potential distribution on the cross-section of an operating metal-oxide-semiconductor field-effect transistor (MOSFET). The temperature distributions were measured both in DC and AC modes in order to take account of the leakage current. The measurement results showed that as the drain bias was increased the hot spot moved to the drain. The density of the iso-potential lines near the drain increased with the increase in the drain bias.
Exhaust Flow Characteristics of Catalytic Converter Adapted to Exhaust Manifold
Park, Young-Cheol ; Lee, Chang-Sik ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 837~844
DOI : 10.3795/KSME-B.2003.27.7.837
The exhaust gas flow in the inlet collector of close coupled catalyst(CCC) adapted to the exhaust manifold is very complex flow because the exhaust gas is a pulsation flow with several port flow. The distribution of gas flow and temperature in inlet collector effect to the efficiency of catalytic converter. In this study, it measures temperatures on several point in inlet collector with two kind of inlet collector volume. And it analyzes with CFD to exhaust manifold and close coupled catalyst for temperature and flow. Comparing to measured and analyzed result, it find increasing of collector volume effects to catalyst temperature distribution and uniformity of catalytic converter
Study on the Effect of Performance Factors on the Finned Tube Type Regenerator for Liquid Desiccant Dehumidification
Jang, Jun-Oh ; Park, Moon-Soo ; Kang, Kyung-Tae ; Lee, Shin-Pyo ; Lee, Jin-Soo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 845~852
DOI : 10.3795/KSME-B.2003.27.7.845
Liquid desiccant dehumidification system can be used effectively to save energy consumed in air conditioning as an alternative compared with conventional air conditioning systems by reducing latent heat load. The dehumidifier and the regenerator from the heart of this system. The latent part of the cooling load is handled using liquid desiccant. In this study, the experimental regenerator has been designed to study the regeneration characteristics of the aqueous triethylene glycol(TEG) system. The performance factors of the regenerator with finned tube heat exchanger were evaluated by a series of experimental runs. The regeneration process is highly dependent on the liquid desiccant conditions, such as, temperature, concentration and flow rate. In addition, the effects of the inlet air temperature, humidity and flow rate were discussed. Data obtained are useful for design guidance and performance analysis of a regenerator, particularly for a liquid desiccant cooling system.
Large Eddy Simulation of Turbulent Channel Flow Through Estimation of Test Filter Width
Choi, Ho-Jong ; Lee, Sang-Hwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 853~858
DOI : 10.3795/KSME-B.2003.27.7.853
The suitable estimation of the filter width in the dynamic eddy viscosity model were investigated in high Reynolds number channel flow. In this study, the improvement on matters by optimizing the test filter shape was attempted through the numerical experiment. The way that select optimum test filter width is recommended. Some test filters, one is based on a discrete representation of the top-hat filter and another are based on a high-order filtering operation, are evaluated in simulations of the turbulent channel flow at Reynolds number 1020, based on friction velocity and channel half width. It appears that the estimation of test filter width practically can decrease the dissipative nature of dynamic eddy viscosity model with explicit test filter. It shows that the value of the filter width ratio used in the dynamic procedure must match the properties of the test filter actually used in the calculation.
Lagrangian Investigation of Turbulent Channel Flow (I) - An Assessment of Particle Tracking Algorithms -
Choi, Jung-Il ; Lee, Chang-Hoon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 859~866
DOI : 10.3795/KSME-B.2003.27.7.859
The Lagrangian dispserion of fluid particles in inhomogeneous turbulence is investigated by a direct numerical simulation of turbulent channel flow. Fluid particle velocity and acceleration along a particle trajectory are computed by employing several interpolation schemes such as linear interpolation, high-order Lagrange polynomial interpolation and the Hermite interpolation schemes. The performances of the schemes are evaluated through comparison of errors in computed particle positions, velocities and accelerations against spectral interpolation. Adopting the four-point Hermite interpolation in the homogeneous directions and Chebyshev polynomials in the wall-normal direction appears to produce most reliable Lagrangian statistics including acceleration correlations with a reasonable amount of computational overhead.
Lagrangian Investigation of Turbulent Channel Flow (II) - Analysis of Lagrangian Statistics -
Choi, Ho-Jong ; Lee, Sang-Hwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 867~876
DOI : 10.3795/KSME-B.2003.27.7.867
The Lagrangian dispersion of fluid particles in inhomogeneous turbulence is investigated by a direct numerical simulation of turbulent channel flow. Four points Hermite interpolation in the homogeneous direction and Chebyshev polynomials in the inhomogeneous direction is adopted to simulate the fluid particle dispersion. An inhomogeneity of Lagrangian statistics in turbulent boundary layer is investigated by releasing many particles at several different wall-normal locations and tracking those particles. The fluid particle dispersions and Lagrangian structure functions of velocity are scaled by the Kolmogorov similarity. The auto-correlations of velocity and acceleration are shown at the different releasing locations. Effect of initial particle location on the dispersion is analyzed by the probability density function at the several downstreams and time instants.
Heat Transfer Analysis in the Vacuum Carburizing Furnace
Lee, In-Sub ; Ryou, Hong-Sun ; Kim, Won-Bae ; Yang, Je-Bok ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 877~882
DOI : 10.3795/KSME-B.2003.27.7.877
The main objective of the present study is to analyze the heat transfer characteristics in the vacuum carburizing furnace. Local temperatures are measured at different locations in the self-fabricated furnace for various operating conditions using K-type thermocouples. In addition, the present study simulates the fluid flows and heat transfer in the vacuum carburizing furnace using a commercial package (Fluent V. 6.0), and compares the predictions of local temperatures with experimental data. The temperature and flow fields are predicted. It is found that the time taken for reaching the steady-state temperature under the vacuum pressure is shorter than that under the normal pressure condition. It means that the carburizing furnace under vacuum pressure condition is capable of saving the required energy more efficiently than the furnace under the normal pressure condition. Furthermore, the temperature variations predicted by the numerical simulations are in good agreement with experimental data.
Structure of Tip Leakage Flow in a Forward-Swept Axial-Flow Fan
Lee, Gong-Hee ; Myung, Hwan-Joo ; Baek, Je-Hyun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 883~892
DOI : 10.3795/KSME-B.2003.27.7.883
The experiment using three-dimensional laser Dopperr velocimetery (LDV) measurements and the computation using the Reynolds stress model of the commercial code, FLUENT, were conducted to give a clear understanding on the structure of tip leakage flow in a forward-swept axial-flow fan operating at the maximum efficiency condition. The tip leakage vortex was generated near the position of the minimum wall static pressure, which was located at approximately 12% chord downstream from the leading edge of blade suction side, and developed along the centerline of the pressure trough within the blade passages. A reverse flow between the blade tip region and the casing, induced by tip leakage vortex, acted as a blockage on the through-flow. As a result, high momentum flux was observed below the tip leakage vortex. As the tip leakage vortex proceeded to the aft part of the blade passage, the strength of tip leakage vortex decreased due to the strong interaction with the through-flow and casing boundary layer, and the diffusion of tip leakage vortex caused by high turbulence. In comparison with LDV measurement data, the computed results predicted the complex viscous flow patterns inside the tip region, including the locus of tip leakage vortex center, in a reliable level.
Effects Of Oxygen Enrichment on the Structure of CH
Lee, Ki-Yong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 893~900
DOI : 10.3795/KSME-B.2003.27.7.893
Numerical simulations of freely propagating flames burning stoichiometric C
mixtures are performed at atmospheric pressure in order to understand the effect of the
enrichment level and the CHC1
molar ratio. A chemical kinetic mechanism is developed, which involves 69 gas-phase species and 379 forward and 364 backward reactions. The calculated flame speeds are compared with the experiments for the flames established at several CHC1
molar ratio (R<1), the results of which is in excellent agreement. As a results of the increased
enrichment level from 0.21 to 1, the flame speed and the temperature in the burned gas are increased. At high CHC1
molar ratio two peak values appear on the
consumption rate, which are affected by CC1
>C1O+CC1O and H＋
A Numerical Study on Stirring Characteristics in a Microchannel with Various Arrangement of Blocks
Suh, Yong-Kweon ; Heo, Hyeung-Seok ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 901~908
DOI : 10.3795/KSME-B.2003.27.7.901
Numerical study on stirring characteristics in a microchannel with blocks arranged periodically has been performed. Viscous flows through the microchannel is simulated three-dimensionally using a commercial code, FLUENT 6.0. Focus is given to the effect on the stirring characteristics of the geometric factors including the pitch, height and angle of the block arrangement. The numerical results at low Reynolds numbers show that the particles` trajectories in the microchannel heavily depend on the block arrangement. A nonlinear dynamical tool, i.e. Lyapunov exponent, was used in analysing the mixing effect. It was found that the mixing is the most effective at a certain combination of parameter values.
Characteristics of Flow over a Pair of Circular Cylinders in a Side-by-Side Arrangement
Kang, Sang-Mo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 909~919
DOI : 10.3795/KSME-B.2003.27.7.909
Two-dimensional flow over a pair of circular cylinders in a side-by-side arrangement at low Reynolds numbers has been numerically investigated in this study Numerical simulations are performed, using the immersed boundary method, for the ranges of 40
＜5, where Re and
are, respectively, the Reynolds number and the spacing between the two cylinder surfaces divided by the cylinder diameter. Results show that a total of six kinds of wake patterns are observed over the ranges: antiphase-synchronized, inphase-synchronized, flip-flopping, single bluff-body, deflected, and steady wake patterns. It is found that the characteristics of the flow significantly depends both on the Reynolds number and gap spacing, with the latter much stronger than the former. Instantaneous flow fields, time traces, flow statistics and so on are presented to identify the wake patterns and then to understand the underlying mechanism. Moreover, the bifurcation phenomenon where either of two wake patterns can occur is found at certain flow conditions.ons.
A Numerical Study on the Steady and Pulsatile Flow with Various Diameter Ratios of Abdominal Aortic Aneurysm
Moh, Jeong-Hah ; Park, Sang-Kyu ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 920~928
DOI : 10.3795/KSME-B.2003.27.7.920
The objective of the present study was to investigate the characteristics of flow and wall shear stress under steady and pulsatile flow in the aneurysm. The numerical simulation using the software were carried out for the diameter ratios ranging from 1.5 to 3.0, Reynolds number ranging from 900 to 1800 and Womersley number, 15.47. For steady flow, it was shown that a recirculating vortex occupied the entire bulge with its core located closer to the distal end of the bulge and the strength of vortex increased with increase of the Reynolds number and diameter ratio. The position of a maximum wall shear stress was the distal end of the aneurysm regardless of the Reynolds number and diameter ratios. For the pulsatile flow, a recirculating flow at the bulge was developed and disappeared for one period and the strength of vortex increased with the diameter ratio. The maximum values of the wall shear stress increased in proportion to the diameter ratio. However, the position of a maximum wall shear stress was the distal end of the aneurysm regardless of the diameter ratios.
Analysis of the Power for a Decanter-Type Centrifuge (I) - Sludge-Removal Power -
Suh, Yong-Kweon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 929~937
DOI : 10.3795/KSME-B.2003.27.7.929
In general, the electric motor for driving the centrifuge of Decanter type is selected based on the power(starting power) necessary to start the bowl and the screw shaft. However the operation cost of the machine is dependent on the power needed at a steadily operating condition, including the power against the bearing friction and that for the sludge removal. In this paper, the formulation for the sludge-removal power is presented. Sample calculation for a specific design shows that the sludge-removal power is increased with the friction coefficient. It also reveals that the power is mainly dependent on the length of the screw blade rather than the beach angle. Further it is shown that the power increases in square of the rotational speed of the machine.
Analysis of the Power for a Decanter-Type Centrifuge (II) - Total Power and the Power-Transmission Mechanism -
Suh, Yong-Kweon ; Han, Geun-Jo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 938~947
DOI : 10.3795/KSME-B.2003.27.7.938
In this paper, we derived the formula for estimating the power of the electric motors needed to operate the Decanter-type centrifuge. In the derivation of the formula the sludge-removal torque is to be supplied from the formula derived in the first paper. The intricate nature of the transmission mechanism in the planetary gear trains of the sludge-removal power and torque has been clarified in this second paper. In particular we considered two-motor system, where the main motor drives the machine while the differential-speed control motor plays the role of braking in adjusting the differential speed. Sample calculation for the specific design treated in the first paper showed that the selection criterion for the main motor depends on the lower limit of the differential speed; when the lower limit is set low, it should be selected based on the steadily operating power, while it should be selected based on the starting power when the lower limit is set high. The total power required by both the main motor and the differential-speed control motor increases as the differential speed is decreased. It is suggested that the power loss in the differential-speed control motor could be minimized by attaching an electric generator to it.
The Effect of Rotation of Discharge Hole on the Discharge Coefficient and Pressure Coefficient
Ha, Kyoung-Pyo ; Ku, Nam-Hee ; Kauh, S.Ken ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 948~955
DOI : 10.3795/KSME-B.2003.27.7.948
Pressure coefficient in rotating discharge hole was measured to gain insight into the influence of rotation to the discharge characteristics of rotating discharge hole. Pressure measurements were done by the telemetry system that had been developed by the authors. The telemetry system measures static pressure using piezoresistive pressure sensors. Pressure coefficients in rotating discharge hole were measured in longitudinal direction and circumferential direction with various rotating speed and 3 pressure ratios. From the results, the pressure coefficient, and therefore the discharge coefficient, is known to decrease with the increase of Ro number owing to the increase of flow approaching angle to the discharge hole inlet. However, there exists critical Ro number where the decrease rate of discharge coefficient with the increase of Ro number changes abruptly; flow separation occurs from the discharge hole exit at this critical Ro number. Critical Ro number increases with the increase of length-to-diameter ratio, but the increase is small where the length-to-diameter ratio is higher than 3. The decrease rate of discharge coefficient with the increase of Ro number depends on the pressure recovery at the discharge hole, and the rate is different from each length-to-diameter ratio; it has tendency that the short discharge hole shows higher decrease rate of discharge coefficient.
Analysis of Effects of Line Tension and Electrical Double Layers on Electrowetting Phenomenon
Chung, Sang-Kug ; Kang, Kwan-Hyoung ; Lee, Choung-Mook ; Kang, In-Seok ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 956~962
DOI : 10.3795/KSME-B.2003.27.7.956
The Lippmann-Young equation has been widely used in electrowetting to predict the contact-angle change of a droplet on a insulating substrate with respect to the externally-applied electrical voltage. The Lippmann-Young equation is derived by assuming a droplet as a perfect conductor, so that the effect of the electrical double layer and the line tension are not taken into account. The validity of the assumption has never been checked before, systematically. In the present investigation, a modified Lippmann-Young equation is derived taking into account of the effect of the electrical double layer and the line tension. To assess their influence on contact-angle change in electrowetting, the electrostatic field around the three-phase contact line is analyzed by solving the Poisson-Boltzmann equation numerically. The validity of the numerical methods is verified by using the past theoretical results on the electrostatic field around a wedge-shaped geometry, which shows fairly good agreement. The results of the present investigation clearly indicate that the effect of the electrical double layer and the line tension is negligible for a millimeter-sized droplet. On the other hand, for a micron-sized droplet, the effect of the line tension can become a dominating factor which controls the contact-angle change in electrowetting.
Performance Predictions of the Planar-type Solid Oxide Fuel Cell with Computational Flow Analysis (II) - Non-isothermal Model -
Hyun, Hee-Chul ; Sohn, Jeong L. ; Lee, Joon-Sik ; Ro, Sung-Tack ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 963~972
DOI : 10.3795/KSME-B.2003.27.7.963
Performance characteristics of the planar-type solid oxide fuel cell (SOFC) are investigated by the analysis of flow fields coupled with heat and mass transfer phenomena in anode and cathode channels. For these purposes, performance analysis of the SOFC is conducted based on electrochemical reaction phenomena in electrodes and electrolyte coupled with flow fields in anode and cathode channels. In the present study, the isothermal model adopted in the previous paper prepared by the same authors is extended to the non-isothermal model by solving energy equation additionally with momentum and mass transfer equations using CFD technique. It is found that the difference between isothermal and non-isothermal models come from non-uniform temperature distribution along anode and cathode electrodes by solving energy equation in non-isothermal model. Non-uniform temperature distribution in non-isothermal model contributes to the increase of average temperature of the fuel cell and influences its performance characteristics.
On the Suitability of Centered and Upwind-Biased Compact Difference Schemes for Large Eddy Smulation (I) - Numerical Test -
Park, No-Ma ; Yoo, Jung-Yul ; Choi, Hae-Cheon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 973~983
DOI : 10.3795/KSME-B.2003.27.7.973
The suitability of high-order accurate, centered and upwind-biased compact difference schemes is evaluated for large eddy simulation of turbulent flow. Two turbulent flows are considered: turbulent channel flow at Re
On the Suitability of Centered and Upwind-Biased Compact Difference Schemes for Large Eddy Smulations (II) - Static Error Analysis -
Park, No-Ma ; Yoo, Jung-Yul ; Choi, Hae-Cheon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 984~994
DOI : 10.3795/KSME-B.2003.27.7.984
The suitability of high-order accurate, centered and upwind-biased compact difference schemes for large eddy simulation is evaluated by a spectral, static error analysis. To investigate the effect of numerical dissipation on LES solutions, power spectra of discretization errors are evaluated for isotropic turbulence models in both continuous and discrete wavevector spaces. Contrary to the common belief, the aliasing errors from upwind-biased schemes are larger than those from comparable non-dissipative schemes. However, this result is the direct consequence of the definition of the power spectral density of the aliasing error, which poses the limitation of the static error analysis for upwind schemes.
On the Suitability of Centered and Upwind-Biased Compact Difference Schemes for Large Eddy Simulations (III) - Dynamic Error Analysis -
Park, No-Ma ; Yoo, Jung-Yul ; Choi, Hae-Cheon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 995~1006
DOI : 10.3795/KSME-B.2003.27.7.995
The suitability of high-order accurate, centered and upwind-biased compact difference schemes for large eddy simulation is evaluated by a dynamic analysis. Large eddy simulation of isotropic turbulence is performed with various dissipative and non-dissipative schemes to investigate the effect of numerical dissipation on the resolved solutions. It is shown by the present dynamic analysis that upwind schemes reduce the aliasing error and increase the finite differencing error. The existence of optimal upwind scheme that minimizes total numerical error is verified. It is also shown that the finite differencing error from numerical dissipation is the leading source of numerical errors by upwind schemes. Simulations of a turbulent channel flow are conducted to show the existence of the optimal upwind scheme.
Performance and Emission Characteristics of Compression Ignition Gasoline Engine
Kim, Hong-Sung ; Kim, Mun-Heon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 27, issue 7, 2003, Pages 1007~1014
DOI : 10.3795/KSME-B.2003.27.7.1007
This work deals with a controlled auto-ignition (CAI) single cylinder gasoline engine, focusing on the extension of operating conditions. The fuel is injected indirectly into electrically heated inlet air flow. In order to keep a homogeneous air-fuel mixing, the fuel injector is water-cooled by a specially designed coolant passage. Investigated are the engine performance and emission characteristics under the wide range of operating conditions such as 32 to 63 in the air-fuel ratio, 1000 to 1800 rpm in the engine speed, and 150 to 18
in the inlet air temperature. The compression ignition gasoline engine can be achieved that the ultra lean-burn with self-ignition of gasoline fuel by heating inlet air. For example. the allowable lean limit of air-fuel ratio is extended until 63 at engine speed of 1000 rpm and inlet air temperature of 17
. It can be achieved that the emission concentrations of carbon monoxide, hydrocarbons and nitrogen oxide had been significantly reduced by CAI combustion compared with conventional spark ignition engine.