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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
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Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 33, Issue 12 - Dec 2009
Volume 33, Issue 11 - Nov 2009
Volume 33, Issue 10 - Oct 2009
Volume 33, Issue 9 - Sep 2009
Volume 33, Issue 8 - Aug 2009
Volume 33, Issue 7 - Jul 2009
Volume 33, Issue 6 - Jun 2009
Volume 33, Issue 5 - May 2009
Volume 33, Issue 4 - Apr 2009
Volume 33, Issue 3 - Mar 2009
Volume 33, Issue 2 - Feb 2009
Volume 33, Issue 1 - Jan 2009
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Experimental Investigation on the Pool Boiling Critical Heat Flux of Water-Based Alumina and Titania Nanofluids on a Flat Plate Heater
Ahn, Ho-Seon ; Kim, Hyung-Dae ; Jo, Hang-Jin ; Kang, Soon-Ho ; Kim, Moo-Hwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 10, 2009, Pages 729~736
DOI : 10.3795/KSME-B.2009.33.10.729
Pool boiling heat transfer and critical heat flux (CHF) of water-based nanofluids with alumina and titania nanoparticles of 0.01% by volume were investigated on a disk heater at saturated and atmospheric conditions. The experimental results showed that the boiling in nanofluids caused the considerable increase in CHF on the flat surface heater. It was revealed by visualization of the heater surface subsequent to the boiling experiments that a major amount of nanoparticles deposited on the surface during the boiling process. Pool boiling of pure water on the surface modified by such nanoparticle deposition resulted in the same CHF increases as what boiling nanofluids, thus suggesting the CHF enhancement in nanofluids was an effect of the surface modification through the nanoparticle deposition during nanofluid boiling. Possible reasons for CHF enhancement in pool boiling of nanofluids are discussed with surface property changes caused by the nanoparticle deposition.
Effect of Coal Properties on Combustion Characteristics in a Pulverized Coal Fired Furnace
Lee, Byoung-Hwa ; Song, Ju-Hun ; Lee, Cheon-Sung ; Chang, Young-June ; Jeon, Chung-Hwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 10, 2009, Pages 737~747
DOI : 10.3795/KSME-B.2009.33.10.737
This study is to investigate the effect of the moisture, volatile matter and particle size in the coal on the pulverized coal combustion characteristics using CFD. The results show that as the moisture content in coal increases, flame temperature decreases because of heat loss driven from latent heat of vaporization and reduction of heating value. As the volatile matter content in the coal increases, the temperature in the region near the burner increases, while the temperature in rear region of boiler decreases. The solution to keep the temperature in the rear region of boiler is suggested that particle size is needed to be larger. As the particle size increases, the temperature in the rear region of boiler show tendency to increase, for combustion burning time of coal could be extended.
Estimation of CO
Reduction by Applying Idling Stop to in-Use Vehicles
Shim, Moo-Kyung ; Rim, Jay-Myoung ; Lee, Beom-Ho ; Hong, Sung-Tae ; Lee, Dae-Yup ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 10, 2009, Pages 748~756
DOI : 10.3795/KSME-B.2009.33.10.748
The effect of idling stop on
reduction was estimated, especially in the area of in-use vehicles. In order to know the fuel saving for each class of vehicles, a methodology to calculate the fuel saving was used along with a standard test using NIER-07 mode. Idling stop execution rate was estimated by analyzing the driving pattern of the in-use city buses, which shows about 75% at maximum. And this corresponds to about 5.4% reduction of the daily total fuel consumption. Finally,
reduction in the automotive sector was estimated, which concludes that, when idling stop device is used, about 480 thousand and 450 thousand tons of
could be reduced with in-use city buses and taxis, respectively. This amount corresponds to about 1.2% of
reduction in the automotive sector.
Local Heat Transfer Characteristics on Fin Surface of Plate Fin-Oval Tube with Delta Wing Vortex Generators
Shin, Seok-Won ; Chung, In-Kee ; Kim, Soo-Youn ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 10, 2009, Pages 757~766
DOI : 10.3795/KSME-B.2009.33.10.757
In the present study, the effect of delta-wing vortex generators(DWVG) on the local heat transfer of the plate fin-oval tube was experimentally analyzed for Reynolds numbers for 2000, 2500 and 3200. The local heat transfer coefficient of the fin surface for four type DWVGs was measured by the naphthalene sublimation technique. As the results, the distribution of the heat transfer coefficient at rear of DWVGs showed longitudinal contours for common flow down DWVGs and wavy contours for common flow up DWVGs. The distribution showed many cell type contours at near wall and downstream for all DWVGs. Compared to case without DWVGs in present experimental tests, all DWVGs showed the best enhancement of heat transfer at Re
Combustion Characteristics of a Staged Burner for a Boiler
Ahn, Joon ; Kim, Jong-Jin ; Kang, Sae-Byul ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 10, 2009, Pages 767~772
DOI : 10.3795/KSME-B.2009.33.10.767
The demand for a boiler with low NOx burner is increasing with the recent strict NOx regulation. Staged burner is a common low NOx burner to suppress the formation of thermal NOx by yielding local fuel rich and lean condition. The staged burner gives fire with bigger frontal area and length compared with a conventional burner, which changes heat transfer characteristics in the combustion chamber. The heat transfer and exhaust gas characteristics have been studied in the present study for a 0.5 t/h class furnace type boiler adopting the staged burner. A numerical simulation has been conducted to clarify the detailed physics inside the combustion chamber.
Fabrication of Carbon Nanotube Strain Sensors
Chang, Won-Seok ; Song, Sun-Ah ; Kim, Jae-Hyun ; Han, Chang-Soo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 10, 2009, Pages 773~777
DOI : 10.3795/KSME-B.2009.33.10.773
In this study, the strain sensing characteristics of single-wall carbon nanotubes(SWCNTs) networks were investigated to develop a film sensor for strain sensing. The SWCNTs film are formed on flexible substrates of poly(ethylene terephthalate) (PET) using spray process. In this manner we could control the transparency and obtain excellent uniformity of the networked SWCNT film. The carbon nanotube film is isotropic due to randomly oriented bundles of SWCNTs. Using experimental results it is shown that there is a nearly linear change in resistance across the film when it is subjected to tensile stress. The results presented in this study indicate the potential of such films for high sensitive transparent strain sensors on macro scale.
The Influence of the Geometry on the Performance of a Thermopneumatic Micropump Operated by Capillary Attraction
Jun, Do-Han ; Yang, Sang-Sik ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 10, 2009, Pages 778~782
DOI : 10.3795/KSME-B.2009.33.10.778
Recently, we developed a simple thermopneumatic micropump having neither a membrane nor a valve. This micropump discharges liquid by a thermopneumatic pressure and refill by a capillary attraction. In case of the micropump driven by the capillary attraction, the flow characteristic depends mainly on the geometry of the micropump. In this paper, we investigated the influence of the geometry of the micropump on the performance of the micropump to illustrate the properness of the micropump shape. We analyzed the micropump characteristics of six types having different geometries by FVM simulation with a commercial CFD tool. Also we fabricated the micropumps with PDMS and glass by micromachining, and tested the performances. The simulation and the test results illustrate that the discharge volume and the discharge time depend on the chamber volume. The expansion angle of the inlet channel location has influence on the refill time, while the front air channel direction has influence on the backward flow loss.
Parametric Study on the Characteristics of Multiphase Laminar Flow with Density Difference in Various Microchannels
Paek, Seung-Ho ; Kim, Dong-Sung ; Choi, Young-Ki ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 10, 2009, Pages 783~788
DOI : 10.3795/KSME-B.2009.33.10.783
In this paper, we have performed a parametric study on the characteristics of multiphase laminar flow with density difference in various microchannels. The interface between multiphase fluids is rotated by the gravitational forces induced by density difference. The numerical simulations were carried out via commercial CFD package to study the characteristics of multiphase laminar flow. The results of the numerical simulations in this study were verified by comparing with the previously reported experimental results in the literature. We have also proposed a new dimensionless relationship between dimensionless rotation angle of interface and dimensionless parameters are proposed for square microchannels with various aspect ratios. The dimensionless relationship could be widely applied to the reliable design of various microfluidic devices dealing with multiphase laminar flow.
A Numerical Study on Droplet Deposition in a Micro-Groove
Lee, Woo-Rim ; Suh, Young-Ho ; Sin, Gi-Hun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 10, 2009, Pages 789~796
DOI : 10.3795/KSME-B.2009.33.10.789
Microdroplet deposition in a micro-groove is studied numerically. The droplet shape is determined by a level-set method which is improved by incorporating a sharp-interface modeling technique for accurately enforcing the matching conditions at the liquid-gas interface and the no-slip and contact angle conditions at an immersed solid surface. The computations are carried out to investigate the droplet behavior derived by the interfacial characteristics between the liquid-gas-solid phases. The effects of contact angle, impact velocity and groove geometry on droplet deposition in a micro-groove are quantified.
Thermal Analysis on Glass Backplane of OLED Displays During Joule Induced Crystallization Process
Kim, Dong-Hyun ; Park, Seung-Ho ; Hong, Won-Eui ; Chung, Jang-Kyun ; Ro, Jae-Sang ; Lee, Seung-Hyuk ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 10, 2009, Pages 797~802
DOI : 10.3795/KSME-B.2009.33.10.797
Large area crystallization of amorphous silicon thin-films on glass substrates is one of key technologies in manufacturing flat displays. Among various crystallization technologies, the Joule induced crystallization (JIC) is considered as the highly promising one in the OLED fabrication industries, since the amorphous silicon films on the glass can be crystallized within tens of microseconds, minimizing the thermally and structurally harmful influence on the glass. In the JIC process the metallic layers can be utilized to heat up the amorphous silicon thin films beyond the melting temperatures of silicon and can be fabricated as electrodes in OLED devices during the subsequent processes. This numerical study investigates the heating mechanisms during the JIC process and estimates the deformation of the glass substrate. Based on the thermal analysis, we can understand the temporal and spatial temperature fields of the backplane and its warping phenomena.
Design and Fabrication of Low-Voltage Twisting-Type Thermal Actuators for Micromirrors
Kim, Dong-Hyun ; Park, Yong-Chul ; Park, Seung-Ho ; Kwon, Oh-Myoung ; Choi, Young-Ki ; Lee, Joon-Sik ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 10, 2009, Pages 803~810
DOI : 10.3795/KSME-B.2009.33.10.803
Micromirrors have a wide range of applications such as optical switches, laser scanners, and digital projection displays. Due to their low performances and high costs, however, practical applications of micromirrors are quite limited. At present micromirrors demand not only a better design but also a simple fabrication process. In this study a twisting-type micromirror that can be driven by two thermal bimorph actuators bending in opposite directions is designed from electro-thermo-mechanical theories and fabricated through a simple MEMS process. Each actuator consists of
and gold thin-film layers. Simplified analytical model has been built to optimize the performance of micromirror. Due to unexpected resistance increase of metal film and alignment mismatch during fabrication process, experimental rotation angles of micromirrors are about
at applied voltages less than 0.6V. From numerical simulation and analytical studies, however, the next design can provide rotation angles over
at the same applied voltage.
Analysis of Filtration Performance by Brownian Dynamics
Bang, Jong-Geun ; Yoon, Yoong-Sup ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 10, 2009, Pages 811~819
DOI : 10.3795/KSME-B.2009.33.10.811
In the present study, deposition of discrete and small particles on a filter fiber was simulated by stochastic method. Trajectory of each particle was numerically solved by Langevin equation. And Lattice Boltzmann method (LBM) was used to solve flow field around the filter collector for considering complex shape of deposit layer. Interaction between the flow field and the deposit layer was obtained from a converged solution from an inner-loop calculation. Simulation method is properly validated with filtration theory and collection efficiency due to different filtration parameters are examined and discussed. Morphology of deposit layer and its evolution was visualized in terms of the particle size. The particle loaded effect on collection efficiency was also discussed.
Effect of Joule Heating Variation on Phonon Heat Flow in Thin Film Transistor
Jin, Jae-Sik ; Lee, Joon-Sik ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 10, 2009, Pages 820~826
DOI : 10.3795/KSME-B.2009.33.10.820
The anisotropic phonon conductions with varying Joule heating rate of the silicon film in Silicon-on-Insulator devices are examined using the electron-phonon interaction model. It is found that the phonon heat transfer rate at each boundary of Si-layer has a strong dependence on the heating power rate. And the phonon flow decreases when the temperature gradient has a sharp change within extremely short length scales such as phonon mean free path. Thus the heat generated in the hot spot region is removed primarily by heat conduction through Si-layer at the higher Joule heating level and the phonon nonlocality is mainly attributed to lower group velocity phonons as remarkably dissimilar to the case of electrons in laser heated plasmas. To validate these observations the modified phonon nonlocal model considering complete phonon dispersion relations is introduced as a correct form of the conventional theory. We also reveal that the relation between the phonon heat deposition time from the hot spot region and the relaxation time in Si-layer can be used to estimate the intrinsic thermal resistance in the parallel heat flow direction as Joule heating level varies.