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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
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Volume & Issues
Volume 29, Issue 12 - Dec 2005
Volume 29, Issue 11 - Nov 2005
Volume 29, Issue 10 - Oct 2005
Volume 29, Issue 9 - Sep 2005
Volume 29, Issue 8 - Aug 2005
Volume 29, Issue 7 - Jul 2005
Volume 29, Issue 6 - Jun 2005
Volume 29, Issue 5 - May 2005
Volume 29, Issue 4 - Apr 2005
Volume 29, Issue 3 - Mar 2005
Volume 29, Issue 2 - Feb 2005
Volume 29, Issue 1 - Jan 2005
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A Study of Cooling of Mobile Phone Using PCM Module
Lee, Sang-Jin ; Jeong, Soo-Jin ; Kim, Woo-Seung ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 11, 2005, Pages 1173~1181
DOI : 10.3795/KSME-B.2005.29.11.1173
The cooling effect of a mobile phone using PCM(Phase Change Material) module has been numerically investigated. A transient three-dimensional numerical analysis of heat and fluid flow with natural convection is performed in this study. Governing conservation equations for mass, momentum and energy are solved by an implicit finite volume method. An enthalpy-porosity technique has been used for modeling of the melting process. Two different ways of placing the PCM module are considered. One is to place a PCM module between the substrate and battery pack, and the other is to place a PCM module between MCM(multichip module) and battery pack. Three different types of PCMs are used to predict the performance of PCM. The results show that passive cooling with PCM can reduce the temperature rise and the effect of natural convection in PCM module considered in this study is negligible.
Development of X-ray PIV Technique and its Application to Blood Flow
Kim, Guk Bae ; Lee, Sang Joon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 11, 2005, Pages 1182~1188
DOI : 10.3795/KSME-B.2005.29.11.1182
An x-ray PIV (Particle Image Velocimetry) technique was developed to measure quantitative information on flows inside opaque conduits and on opaque-fluid flows. At first, the developed x-ray PIV technique was applied to flow in an opaque Teflon tube. To acquire x-ray images suitable for PIV velocity field measurements, refraction-based edge enhancement mechanism was employed using detectable tracer particles. The optimal distance between with the sample and detector was experimentally determined. The resulting amassed velocity field data were in reasonable agreement with the theoretical prediction. The x-ray PIV technique was also applied to blood flow in a microchannel. The flow pattern of blood was visualifed by enhancing the diffraction/interference -bas ed characteristic s of blood cells on synchrotron x-rays without any contrast agent or tracer particles. That is, the flow-pattern image of blood was achieved by optimizing the sample (blood) to detector distance and the sample thickness. Quantitative velocity field information was obtained by applying PIV algorithm to the enhanced x-ray flow images. The measured velocity field data show a typical flow structure of flow in a macro-scale channel.
Response of Spatially Developing Turbulent Boundary Layer to Spanwise Oscillating Electromagnetic Force
Lee, Joung-Ho ; Sung, Hyung Jin ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 11, 2005, Pages 1189~1198
DOI : 10.3795/KSME-B.2005.29.11.1189
Direct numerical simulations were performed to investigate the physics of a spatially developing turbulent boundary layer flow subjected to spanwise oscillating electromagnetic forces in the near wall region. A fully implicit fractional step method was employed to simulate the flow. The mean flow properties and the Reynolds stresses were obtained to analyze the near-wall turbulent structure. It is found that skin friction and turbulent kinetic energy can be reduced by the electromagnetic forces. The decrease in production is responsible fur the reduction of turbulent kinetic energy. Instantaneous flow visualization techniques were used to observe the response of streamwise vortices and streak structures to spanwise oscillating forces. The near-wall vortical structures are affected by spanwise oscillating electromagnetic forces. Following the stopping of the electromagnetic force, the flow eventually relaxes back to a two-dimensional equilibrium boundary layer.
A Study on Characteristics of the Flow Around Two Square Cylinders in a Tandem Arrangement Using Particle Image Velocimetry
Kim, Dong-Keon ; Lee, Jong-Min ; Seong, Seung-Hak ; Yoon, Soon-Hyun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 11, 2005, Pages 1199~1208
DOI : 10.3795/KSME-B.2005.29.11.1199
The flow fields including velocities, turbulence intensities, Reynolds shear stress and turbulent kinetic energy were investigated using particle image velocimetry(PIV) to study the flow characteristics around two square cylinders in a tandem arrangement. The experiments were carried out in the range of the spacing from 1.0 to 4.0 widths of cylinder, Reynolds number of 5.3
respectively. Discontinuous jumping at the drag coefficient variation was found for two cylinders simultaneously when the spacing between two cylinders is varied. This phenomenon is attributed to a sudden change of the flow pattern which depends on the reattachment of the shear layer separated from the upstream cylinder. Near such a critical spacing, the changes of the flow fields as well as the effect of Reynolds number were studied in detail.
The Thermocapillary Effect on Pure Conduction Mechanism in a Closed Square Cavity
Yu, Jae-Bong ; An, Do-Won ; Yoo, Joo-Sik ; Eom, Yong-Kyoon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 11, 2005, Pages 1209~1219
DOI : 10.3795/KSME-B.2005.29.11.1209
In a closed square cavity filled with a liquid, a cooling horizontal upper wall and a heating lower wall, the flow isn't generated under the ground-based condition when Rayleigh number is lower than 1700. In this mechanism, Ra=1534, Temperature and velocity fields near an air-bubble in silicon-oil under a cooled upper wall were investigated. Temperature and velocity fields is visualized using the thermo-sensitive liquid-crystal and light sheet visualization technique. The quantitative analysis fer the temperature and the flow fields were carried out by applying the image processing technique to the original data. The symmetry shape of two vortexes near an air bubble was observed. As the bubble size increased, the size of vortex and the magnitude of velocity increased. In spite of elapsed time, a pair of vortexes was the unique and steady-state flow in a square cavity and wasn't induced to the other flow in the surround region.
Fuzzy Algorithm for FDD Technique Development of System Multi-Air Conditioner
Choi, C. S. ; Tae, S. J. ; Kim, H. M. ; Cho, K. N. ; Moon, J. M. ; Kim, J. Y. ; Kwon, H. J. ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 11, 2005, Pages 1220~1228
DOI : 10.3795/KSME-B.2005.29.11.1220
Fault detection and diagnostic (FDD) systems have the potential to reduce equipment downtime, service costs, and utility costs. In this study, model based algorithm and fuzzy algorithm were used to detect and diagnose various fault at System multi-air conditioner. various fault include the Refrigerant Low charging, Fouling of Indoor Heat Exchanger, Fouling of Outdoor Heat Exchanger A experimental verification was conducted in the 6HP System multi-air conditioner on an 8-floor building. Test results showed diagnosis result about 78
for given faults. This Study lays the foundation fur future work on develope the real-time fault detection and diagnosis system for the System multi-air conditioner.
A Study of Efficacy of Physical Water Treatment Devices for Mineral Fouling Mitigation Using Artificial Hard Water
Pak, Bock Choon ; Kim, Sun Do ; Baek, Byung Joon ; Lee, Dong Hwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 11, 2005, Pages 1229~1238
DOI : 10.3795/KSME-B.2005.29.11.1229
The objective of the present study was to investigate the efficacy of physical water treatment (PWT) technologies using different catalytic materials and an electronic anti-fouling device in the mitigation of mineral fouling in a once-through flow system with mini-channel heat exchanger. Effects of flow velocity and water hardness on the effectiveness of PWT technologies were experimentally studied. The artificial water hardness varied from 5.0 to 10 mo1/m
. For 10 mo1/m
solution, fouling resistance reduced by 13-40
depending on flow velocity and types of PWT devices. On the other hand, fouling resistance reduced by 21-29
depending on the PWT devices for 5 mo11m3 solutions. The PWT device using alloy of Cu and Zn as catalyst (CM2) was slightly more effective than the others. SEM photographs of scale produced from the 10 mol/m
solution at 1.0 m/s indicated that calcium carbonate scales without PWT devices were needle-shaped aragonite, which is sticky, dense and difficult to remove. Scales with the PWT devices showed a cluster of spherical or elliptic shape crystals. Both the heat transfer test results and SEM photographs strongly support the efficacy of PWT technologies using catalytic materials and an electronic anti-fouling device in the mitigation of mineral fouling.
A Study on the Suppression of Cavitation in Inducer by J-Groove
Choi, Young-Do ; Kurokawa, Junichi ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 11, 2005, Pages 1239~1247
DOI : 10.3795/KSME-B.2005.29.11.1239
Cavitation is the most serious problem in developing high-speed turbopump, and inducer is often used to avoid cavitation in main impeller. Thus, inducer is always operating in the worst .cavitation condition. If it is possible to control and suppress cavitation in inducer by some new device, it might be possible to suppress cavitation occurring in any type of pumps. The purpose of present study is to develop a new effective method of controlling and suppressing cavitation in inducer using shallow grooves, which is named 'J-Groove'. J-Groove is installed on the casing wall near the blade tip to use the pressure difference between high pressure region and low pressure region of the inducer in an axial direction. The results show that proper combination of backward-swept inducer with J-Groove improves suction performance of turbopump remarkably in the range of partial flow rate as well as designed flow rate. The rotating backflow cavitation occurring in the range of low flow rate and the cavitation surge occurring in the vicinity of the best efficiency point can be almost suppressed by installing J-Groove.
A Study on the Flow Characteristics of Emulsified Fuel by the Ultrasonic Energy in Tube
Koh, Kyounghan ; Lee, Seungjin ; Lee, Byongo ; Ryu, Jeongin ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 11, 2005, Pages 1248~1256
DOI : 10.3795/KSME-B.2005.29.11.1248
This study was undertaken to investigate the flow characteristics of emulsified fuel with the ultrasonic energy-adding system by using the chaotic method. Efffcts of water contents within emulsified fuel, flow rate and tube length with 5m in diameter from an emulsified chamber has been discussed on the strange attractor and power spectral density function. Five probe sensors were set up from 0.5 to 2.5m by length in 0.5m increments in the tube. In particular, the chaotic features of this system have been practically characterized in terms of chaotic statistics such as the power spectral density function and phase space portraits by resorting to the somewhat noble deterministic chaos theory. In the tube, the dominant frequency increased with increasing water contents and flow rate, but decreased a little with an increase in the length from the emulsified chamber.
An Inverse Analysis on the Estimation of Two-dimensional Overall Heat Absorptance on the Slab in the Reheating Furnace
Kang, Deok-Hong ; Kwag, Dong-Seong ; Kim, Woo-Seung ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 11, 2005, Pages 1257~1264
DOI : 10.3795/KSME-B.2005.29.11.1257
An inverse problem to determine two-dimensional total heat exchange factor is studied for the prediction of the slab temperature in the reheating furnace. Temperature measurements by the experiment are used in the inverse analysis. This inverse analysis employs the conjugate gradient method. The overall heat absorptances for 12-zones of the cross-section of the slab are estimated. The estimated temperatures at measurement locations are in good agreements with the measured temperatures.
Prediction of Combined Forced and Natural Turbulent Convection in a Vertical Plane Channel with an Elliptic-Blending Second Moment Closure
Shin, Jong Keun ; An, Jeong Soo ; Choi, Young Don ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 11, 2005, Pages 1265~1276
DOI : 10.3795/KSME-B.2005.29.11.1265
The elliptic conceptual second moment models for turbulent heat fluxes, which are proposed on the basis of elliptic-blending and elliptic-relaxation equations, are applied to calculate the combined forced and natural turbulent convection in a vertical plane channel. The models satisfy the near-wall balance between viscous diffusion, viscous dissipation and temperature-pressure gradient correlation, and also have the characteristics of approaching its respective conventional high Reynolds number model far away from the wall. Also the models are closely linked to the elliptic blending model which is used for the prediction of Reynolds stress. In order to calibrate the heat flux models, firstly, the distributions of mean temperature and scala flux in fully developed channel flow with constant wall difference temperature are solved by the present models. The buoyancy effect on the turbulent characteristics including the mean velocity and temperature, the Reynolds stress tensor, and the turbulent heat flux vector are examined. In the opposing flow, the turbulent transport is greatly enhanced with both the Reynolds stresses and the turbulent heat fluxes being remarkably increased; whereas, in the aiding flow, the opposite change is observed. The results of prediction are directly compared to the DNS to assess the performance of the model predictions and show that the behaviors of the turbulent heat transfer in the whole flow region are well captured by the present models.
Combustion Characteristics for Varying Flow Velocity on Methane/Oxygen Diffusion Flames
Kim, Ho-Keun ; Lee, Sang-Min ; Ahn, Kook-Young ; Kim, Yong-Mo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 11, 2005, Pages 1277~1284
DOI : 10.3795/KSME-B.2005.29.11.1277
The combustion characteristics of methane oxygen diffusion flames have been investigated to give basic information for designing industrial oxyfuel combustors. NOx reduction has become one of the most determining factors in the combustor design since the small amount of nitrogen is included from the current low cost oxygen production process. Flame lengths decreased with increasing fuel or oxygen velocity because of the enhancement of mixing effect. Correlation equation between flame length and turbulent kinetic energy was proposed. NOx concentration was reduced with increasing fuel or oxygen velocity because of the enhanced entrainment of the product gas into flame zone as well as the reduction of residence time in combustion zone.