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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 30, Issue 12 - Dec 2006
Volume 30, Issue 11 - Nov 2006
Volume 30, Issue 10 - Oct 2006
Volume 30, Issue 9 - Sep 2006
Volume 30, Issue 8 - Aug 2006
Volume 30, Issue 7 - Jul 2006
Volume 30, Issue 6 - Jun 2006
Volume 30, Issue 5 - May 2006
Volume 30, Issue 4 - Apr 2006
Volume 30, Issue 3 - Mar 2006
Volume 30, Issue 2 - Feb 2006
Volume 30, Issue 1 - Jan 2006
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Analysis of Flow Resistance in Microchannels at Slip-Flow Regime by Direct Simulation Monte Carlo Method
Sung Jaeyong ; Ahn Youngkyoo ; Lee Sukjong ; Lee Myeong Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 1, 2006, Pages 1~7
DOI : 10.3795/KSME-B.2006.30.1.001
The characteristics of micro gaseous flows in microchannels have been analyzed in view of flow resistance using the direct simulation Monte Carlo (DSMC) method which is a molecule-based numerical modeling technique. For this purpose, a DSMC code where the pressure boundary condition was specified at the inlet and outlet, has been developed and the results of simulations showed satisfactory agreements with the analytic solution in the slip flow regime. (0.01 < Kn < 0.1) By varying the height and length of the microchannel, the effect of pressure difference between the inlet and outlet was examined. The present computation indicates that the curvature in pressure distribution along the channel increases due to the effect of compressibility when the pressure difference increases. To obtain the flow resistance regardless of the channel dimensions, a standard curve is devised in the present study by introducing the concept of unit mass flowrate and unit driving pressure force. From this curve, it is shown that in micro flows, a significant deviation from the laminar incompressible flow occurs by reducing the flow resistance.
Sparse Point Representation Based on Interpolation Wavelets
Park, Jun-Pyo ; Lee, Do-Hyung ; Maeng, Joo-Sung ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 1, 2006, Pages 8~15
DOI : 10.3795/KSME-B.2006.30.1.008
A Sparse Point Representation(SPR) based on interpolation wavelets is presented. The SPR is implemented for the purpose of CFD data compression. Unlike conventional wavelet transformation, the SPR relieves computing workload in the similar fashion of lifting scheme that includes splitting and prediction procedures in sequence. However, SPR skips update procedure that is major part of lifting scheme. Data compression can be achieved by proper thresholding method. The advantage of the SPR method is that, by keeping even point physical values, low frequency filtering procedure is omitted and its related unphysical thresholing mechanism can be avoided in reconstruction process. Extra singular feature detection algorithm is implemented for preserving singular features such as shock and vortices. Several numerical tests show the adequacy of SPR for the CFD data. It is also shown that it can be easily extended to nonlinear adaptive wavelets for enhanced feature capturing.
Hydraulic Design Procedure for Regenerative Flow Pumps
Yoo, Il-Su ; Park, Mu-Ryong ; Chung, Myoung-Kyoon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 1, 2006, Pages 16~23
DOI : 10.3795/KSME-B.2006.30.1.016
The present study aims at establishing the design procedure of regenerative pumps. It is based on the new momentum exchange theory proposed in Yoo, Park and Chung. Salient feature of the present design procedure is that it does not require input of any kinds of empirical design data. Using the design procedure, a prototype regenerative pump has been designed and manufactured to confirm its validity. Comparison between the predicted performance and the experimental measurement reveals that the prototype pump has its maximum efficiency at the design flow rate and that the proposed performance analysis method satisfactorily predicts the machine performance.
A Study of Beat Transfer Characteristics of Large Scale Vortex Flow Mixing Vane of Nuclear Fuel Rod Bundle
An, Jeong-Soo ; Choi, Young-Don ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 1, 2006, Pages 24~31
DOI : 10.3795/KSME-B.2006.30.1.024
Mixing vanes have been installed in the space grid of nuclear fuel rod bundle to improve turbulent heat transfer. Split mixing vanes induce the vortex flow in the cooling water to swirl in sub-channel of fuel assembly. But, The swirling flow decays rapidly so that the heat transfer enhancing effect limited to short length after the mixing vane. In thi present study, the large scale vortex flow(LSVF) is generated by rearranging the mixing vanes to the coordinated directions. This LSVF mixing vanes generate the most strong secondary flow vortices which maintain about 35
after the spacer grid. The streamwise vorticity generated by LSVF sustain two times more than that split mixing vane. Heat transfer in the rod bundle occurs greatly at the same direction to cross flow, and maximum temperature at the surface of bundle drops about 1.5K
A Study on the Acoustic Damping Characteristics of Acoustic Cavities in a Liquid Rocket Combustor
Kim Hong Jip ; Kim Seong-Ku ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 1, 2006, Pages 32~40
DOI : 10.3795/KSME-B.2006.30.1.032
A linear acoustic analysis has been performed to elucidate damping characteristics of acoustic cavities in a liquid rocket combustor. Results have shown that resonant frequencies of acoustic cavity obtained by classical theoretic approach and by the present linear analysis are somewhat different with each other. This difference is attributed to the limitation of the simplified classical theory. To quantify the damping characteristics, acoustic impedance has been introduced and resultant absorption coefficient and conductance have been evaluated. Satisfactory agreement has been achieved with previous experiment. Finally the design procedure for an optimal tuning of acoustic cavity has been established.
Development of Nanoscale Thermoelectric Coefficient Measurement Technique Through Heating of Nano-Contact of Probe Tip and Semiconductor Sample with AC Current
Kim, Kyeongtae ; Jang, Gun-Se ; Kwon, Ohmyoung ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 1, 2006, Pages 41~47
DOI : 10.3795/KSME-B.2006.30.1.041
High resolution dopant profiling in semiconductor devices has been an intense research topic because of its practical importance in semiconductor industry. Although several techniques have already been developed. it still requires very expensive tools to achieve nanometer scale resolution. In this study we demonstrated a novel dopant profiling technique with nanometer resolution using very simple setup. The newly developed technique measures the thermoelectric voltage generated in the contact point of the SPM probe tip and MOSFET surface instead of electrical signals widely adopted in previous techniques like Scanning Capacitance Microscopy. The spatial resolution of our measurement technique is limited by the size of contact size between SPM probe tip and MOSFET surface and is estimated to be about 10 nm in this experiment.
Effect of Swirling Flow by Normal Injection of Secondary Air on the Gas Residence Time and Mixing Characteristics in a Combustor
Park Sang-Uk ; Jeon Byoung-Il ; Yu Tae-U ; Hwang Jung-Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 1, 2006, Pages 48~56
DOI : 10.3795/KSME-B.2006.30.1.048
We investigated gas residence time and mixing characteristics due to various swirl numbers generated by normal injection of secondary air to a lab-scale cylinderical combustor. The residence time was estimated by measuring the temporal pressure difference which was caused by deposition of test particles on a filter media after the injection by a syringe. The mixing characteristics were evaluated by standard deviation value of test gas concentration at different measuring points. The test gas concentration was detected by a gas analyzer. The swirl number of
caused long residence time enough to improve mixing characteristics. Numerical calculations were also carried out to understand physical meanings of the experimental results.
Study on Thermal Comfort and Indoor Air Quality in the Classroom with System Air-conditioner and Ventilation System for Cooling Loads
Noh Kwang-Chul ; Jang Jae-Soo ; Oh Myung-Do ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 1, 2006, Pages 57~66
DOI : 10.3795/KSME-B.2006.30.1.057
The experimental and the numerical study was performed on the comparison of thermal comfort(TC) and indoor air quality(IAQ) in the lecture room for cooling loads when the operating conditions are changed. PMV value and
concentration of the lecture room were measured and compared with the numerical results. The numerical results showed a good agreement with the experimental one and then the numerical tool was used to analyze thermal comfort and IAQ for a couple of operating conditions. As a result it was found that the increment of the discharge angle of system air-conditioner makes TC uniformity worse, but rarely affects IAQ. Also TC and IAQ were hardly affected by the variation of the discharge airflow. Finally it turned out that TC is merely affected by the increment of the ventilation airflow, but the average
concentration can be satisfied with Japanese IAQ standards of classrooms when the ventilation airflow is more than
in this study.
Study on Angular Momentum Transfer in Polymer Solutions
Kim, Jae-Won ; Ahn, Eun-Young ; Oh, Jung-Su ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 1, 2006, Pages 67~73
DOI : 10.3795/KSME-B.2006.30.1.067
This investigation deals with the spin-up flows in a circular container of aspect ratio, 2.0. Shear front is generated in the transient spin-up process and propagating from the side wall to the central axis in a rotating container. Propagation of the shear front to the axis in a rotating container means the region acquires an angular momentum transfer from the solid walls. Propagating speed of the shear front depends on the apparent viscosity of polymer solution. Two kinds of polymer solutions are considered as a working fluid: one is CMC and the other is CTAB solution. CMC solution has larger apparent viscosity than that of water, and CTAB shows varying apparent viscosities depending on the applied shear rates. Transient and spatial variations of the apparent viscosities of the present polymer solutions (CTAB and CMC) cause different speeds of the propagating shear front. In practice, CMC solution that has larger values of apparent viscosity than that of water always shows rapid approach to the steady state in comparison of the behavior of the flows with water. However, for the CTAB solution, the speed of the propagating of the shear front changes with the local magnitude of its apparent viscosity. Consequently, the prediction of Wedemeyer's model quantitatively agrees with the present experimental results.
An Experimental Study on Boiling Heat Transfer of PF5060 on the Shape and Orientation of Micro-Fin Surfaces
Kim Yoon-Ho ; Kim Choong ; Lee Kyu-Jung ; Kim Youngchan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 1, 2006, Pages 74~81
DOI : 10.3795/KSME-B.2006.30.1.074
Experiments to measure the pool boiling heat transfer on the micro-fin surfaces were performed with PF5060. The effects of various orientation and subcooling of heat surface on pool boiling performance were investigated under various heat-flux conditions for plain and micro-fin surfaces. The comparison between the results of this study and those of previous work shows a similar trend at the same conditions. From the results, it is proved that nucleate boiling performance is strongly dependent on the orientation, the micro-fin structure and the subcooling of heat surface. The heat flux on the surface with orientation angles of
was larger than that on horizontal surface(
) at same wall superheat because of the effect of bubble sweeping. The nucleate boiling performance of micro-fin surfaces is enhanced by decreasing the fin size(WxL) and the pitch, respectively. The subcooling makes nucleate boiling performance lower for both micro-fin and plain surfaces.
Electrostatic Ejection of Micro-droplets Containing Carbon Nanotubes
Kim Yong-Jae ; Lee Sukhan ; Ko Han Seo ; Byun Doyoung ; Han Sangjoon ; Yang Ji Hye ; Baik Seunghyun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 1, 2006, Pages 82~86
DOI : 10.3795/KSME-B.2006.30.1.082
Carbon nanotubes have attracted much attention as future mechanical and electronic materials. However, manipulating techniques are not well developed yet. Here we propose to use electrostatic drop-on-demand devices to eject micro-droplets containing micelle-suspended single-walled carbon nanotubes. A simple electrostatic force analysis and photographic studies of droplet ejection process are presented. The analytical analysis shows that semiconducting species have higher electrostatic force density. However, enrichment of specific electronic types is not clear at large size droplets produced in this study. A micro-scale jetting device is being produced to prove the suggested behavior.
Hydraulic Design Optimization and Performance Analysis of a Centrifugal Blood Pump
Park Moo Ryong ; Yoo Seong Yeon ; Oh Hyoung Woo ; Yoon Eui Soo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 1, 2006, Pages 87~94
DOI : 10.3795/KSME-B.2006.30.1.087
This paper presents the hydrodynamic design and performance analysis method for a miniaturized centrifugal blood pump using three-dimensional computational fluid dynamics (CFD) code. In order to obtain the hydraulically high efficient configuration of a miniaturized centrifugal blood pump for cardiopulmonary circulation, a well-established commercial CFD code was incorporated considering detailed flow dynamic phenomena in the blood pump system. A prototype of centrifugal blood pump developed by the present design and analysis method has been tested in the mock circulatory system. Predicted results by the CFD code agree very well with in vitro hydraulic performance data for a centrifugal blood pump over the entire operating conditions. Preliminary in vivo animal testing has also been conducted to demonstrate the hemodynamic feasibility for use of centrifugal blood pump as a mechanical circulatory support. A miniaturized centrifugal blood pump developed by the hydraulic design optimization and performance prediction method presented herein shows the possibility of a good candidate for intra and extracorporeal cardiopulmonary circulation pump in the near future.