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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 38, Issue 12 - Dec 2014
Volume 38, Issue 11 - Nov 2014
Volume 38, Issue 10 - Oct 2014
Volume 38, Issue 9 - Sep 2014
Volume 38, Issue 8 - Aug 2014
Volume 38, Issue 7 - Jul 2014
Volume 38, Issue 6 - Jun 2014
Volume 38, Issue 5 - May 2014
Volume 38, Issue 4 - Apr 2014
Volume 38, Issue 3 - Mar 2014
Volume 38, Issue 2 - Feb 2014
Volume 38, Issue 1 - Jan 2014
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Thermo-Hydraulic Characteristics of Two-Dimensional Wavy Channels with Different Shape Parameters
Kim, Ki-Wan ; Kim, Sun-Ju ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 1, 2014, Pages 1~8
DOI : 10.3795/KSME-B.2014.38.1.001
Two-dimensional laminar numerical analyses were carried out for investigating the thermo-hydraulic characteristics of wavy channels with different shape parameters (
). PAO (polyalphaolefin), which is used for electronics cooling, is considered as the working fluid. In addition, constant properties, periodically developed flow, and uniform channel wall temperature conditions are assumed. Streamline and temperature fields, isothermal Fanning friction factors, and Colburn factors are presented for different Reynolds numbers in the laminar region (
). The results show that heat transfer is enhanced when the channel corrugation ratio (
) is large and channel spacing ratio (
) is small in the low Reynolds number region (Re < 50) and when
are large in the high Reynolds number region (
Flow and Displacement of Non-Newtonian Fluid(Power-Law Model) by Surface Tension and Gravity Force in Inclined Circular Tube
Moh, Jeong Hah ; Cho, Y.I. ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 1, 2014, Pages 9~16
DOI : 10.3795/KSME-B.2014.38.1.009
This paper presents the theoretical analysis of a flow driven by surface tension and gravity in an inclined circular tube. A governing equation is developed for describing the displacement of a non-Newtonian fluid(Power-law model) that continuously flows into a circular tube owing to surface tension, which represents a second-order, nonlinear, non-homogeneous, and ordinary differential form. It was found that quantitatively, the theoretical predictions of the governing equation were in excellent agreement with the solutions of the equation for horizontal tubes and the past experimental data. In addition, the predictions compared very well with the results of the force balance equation for steady.
Measurement of Black Carbon Concentration in Rural Area
Lee, Ki Woong ; Han, Seung Cheol ; Lee, Jeonghoon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 1, 2014, Pages 17~24
DOI : 10.3795/KSME-B.2014.38.1.017
We measured black carbon concentration in rural area to understand the characteristic of atmospheric aerosol by comparing the black carbon concentration and meteorological factors such as PM10 concentration, relative humidity, temperature and wind velocity. A MAAP (Multi Angle Absorption Photometer) which is one of filter based equipments was used to measure black carbon concentration. Black carbon concentration was measured to be high from April to May and low from June to September. Black carbon concentration was proportional to PM10 concentration. Black carbon concentration was correlated to relative humidity. Black carbon concentration was inversely proportional to wind velocity and temperature. Finally, we suggest that the volume fraction of black carbon in the atmosphere can be estimated from the size, number concentration and absorption coefficient measured using the MAAP.
Flow Characteristics of Two Types of Overhung Compressor Volute for Automobile Turbocharger
Tianjun, Zhou ; Lee, Geun Sik ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 1, 2014, Pages 25~30
DOI : 10.3795/KSME-B.2014.38.1.025
The flow characteristics of two types of overhung compressor volutes for automobile turbochargers were analyzed numerically using commercial software. For obtaining high performance from a volute, it is necessary that the volute have a high pressure recovery coefficient and a low loss coefficient. We investigated the flow characteristics of two types of overhung compressor volutes with a fixed diffuser inlet angle of
and a mass flow rate of 0.055 kg/s. The first type is a volute with one-arc cross section (type 1) and the second type is with three-arc cross section (type 2). Our results showed that between the two types of volutes, type 2 had the higher pressure recovery coefficient and the lower loss coefficient along the entire angular position.
Performance Prediction and Economic Assessment of Atmospheric Pressure MCFC/Gas Turbine Hybrid System with Indirect Turbine Firing
Choi, Joo Hwan ; Kim, Tong Seop ; Kwak, Bu Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 1, 2014, Pages 31~39
DOI : 10.3795/KSME-B.2014.38.1.031
The performance of fuel cell/gas turbine hybrid systems is highly affected by system configuration. In this study, the performance of a hybrid system combining a molten carbonate fuel cell (MCFC) and an indirectly fired gas turbine was predicted. Firstly, general performance trends of the hybrid system depending on major design parameters were examined. Then, the most feasible design options with the least impact on the MCFC stack design conditions were drawn. The economic advantage of the hybrid system over the basic MCFC only system was evaluated.
Numerical Investigation of the Spray Behavior and Flow Characteristics of Urea-Water Solution Injected into Diesel Exhaust Pipe
An, Tae Hyun ; Kim, Man Young ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 1, 2014, Pages 41~48
DOI : 10.3795/KSME-B.2014.38.1.041
A urea-SCR system suffers from some issues associated with the ammonia slip phenomenon, which mainly occurs because of the shortage of evaporation and thermolysis time, and this makes it difficult to achieve an uniform distribution of injected urea. A numerical study was therefore performed by changing such various parameters as installed injector angle and application and angle of mixer to enhance evaporation and the mixing of urea water solution with exhaust gases. As a result, various parameters were found to affect the evaporation and mixing characteristics between exhaust gas and urea water solution, and their optimization is required. Finally, useful guidelines were suggested to achieve the optimum design of a urea-SCR injection system for improving the DeNOx performance and reducing ammonia slip.
Development of Heating Device Using Concentrator Solar Cells
Lee, Dong Il ; Baek, Seung Wook ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 1, 2014, Pages 49~56
DOI : 10.3795/KSME-B.2014.38.1.049
In this study, the generation efficiency of the limited area of a concentrator solar cell was increased by using a solar concentrator and a tracking device. Heat generated by the solar cell was collected using a thermal absorber for supplying hot water or heating. Thus, the concentrator solar cell system provided electricity and heat simultaneously. Tracking of the sun by detecting the sun's position, repositioning of heating device towards the east after sunset, and shutting down of system after sunset were successfully implemented using an illuminance sensor (CdS) and Simulink, a commercial software package. We performed parametric analysis of the velocity, fin installation, and entrance location with respect to the operating temperature of the concentrator solar cell. A heat transfer simulation model was developed for comparing the actual temperature profiles of the concentrator solar cell and thermal absorber, and good agreement was found between the results of the simulations and the experiments.
Identification of Muscle Forces and Activation of Quadriceps Femoris Muscles of Healthy Adults Considering Knee Damping Effects during Patellar Tendon Reflex
Kang, Moon Jeong ; Jo, Young Nam ; Yoo, Hong Hee ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 1, 2014, Pages 57~62
DOI : 10.3795/KSME-B.2014.38.1.057
Most analytical models of the human body have focused on conscious responses. A patellar tendon reflex, a representative example of spinal reflexes, occurs without a neural command. Muscle forces and activation of the quadriceps femoris muscles in healthy adults during patellar tendon reflex are identified in this study. The model is assumed to move in the sagittal plane, and the thigh and the trunk are assumed to be fixed in a sitting position so that the shank can move similar to a pendulum. The knee joint is modeled as a revolute joint, and the ankle joint is modeled as a fixed joint so that the shank and the foot can be regarded as one rigid body. Muscle forces are calculated following the inverse dynamic approach. Kinematic data obtained from an experiment (Mamizuka, 2007) are used as input data. Muscle activations are identified using a Hill-type muscle model. The obtained simulation results are compared with experimental results for validating the model and the underlying assumptions.
Effect of Stent Design Porosity on Hemodynamics Within Cerebral Aneurysm Model: Numerical Analysis
Phan, Dai Thanh ; Lee, Sang-Wook ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 1, 2014, Pages 63~70
DOI : 10.3795/KSME-B.2014.38.1.063
In the present study, CFD simulations were conducted for investigating intra-aneurysmal flow characteristics with different stent porosities (
= 80%, 74%, and 64%), and the simulation results were compared with experimental data. Using a quadratic tetrahedral element-based finite element scheme, we estimated velocity fields and wall shear stress. The intra-aneurysmal velocity reduction ratios obtained via simulation agree well with published experimental data. It was found that a stent with a porosity of 80%, which is highest in the present study, is able to effectively reduce flow into the aneurysm, which causes intra-aneurysmal stasis, and that stents with lower porosities afford only incremental benefits in reducing inflow to an aneurysm.
Performance Analysis of the Parallel CUPID Code for Various Parallel Programming Models in Symmetric Multi-Processing System
Jeon, Byoung Jin ; Lee, Jae Ryong ; Yoon, Han Young ; Choi, Hyoung Gwon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 1, 2014, Pages 71~79
DOI : 10.3795/KSME-B.2014.38.1.071
A parallelization of the bi-conjugate gradient solver for the pressure equation of the CUPID (component unstructured program for interfacial dynamics) code, which was developed for analyzing the components of a pressurized water-cooled reactor, was studied in a symmetric multi-processing system. The parallel performance was investigated for three typical parallel programming models (MPI, OpenMP, Hybrid) by solving incompressible backward-facing step flow at various grid resolutions. It was confirmed that parallel performance was low when problem size was small or the memory requirement for each thread was considerably higher than the cache memory. Furthermore, it was shown that MPI was better than OpenMP regardless of the problem size, and Hybrid was the best when the number of threads was relatively small.
Measurement of Average Pool Boiling Heat Transfer Coefficient on Near-Horizontal Tube
Kang, Myeong-Gie ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 1, 2014, Pages 81~88
DOI : 10.3795/KSME-B.2014.38.1.081
An experimental study is performed to obtain an average heat transfer coefficient around the perimeter of a near horizontal tube. For the test a stainless steel tube of 50.8 mm diameter submerged in water at atmospheric pressure is used. Both subcooled and saturated pool boiling conditions are considered and the inclination angle of the tube is changed from the horizontal position to
in steps of
. In saturated water, the local boiling heat transfer coefficient at the azimuthal angle of
from the tube bottom can be regarded as the average of the coefficients regardless of the tube inclination angles. However, when the water is subcooled the location for the average heat transfer coefficient depends on the inclination angle and the heat flux. It is explained that the major mechanisms changing the heat transfer are closely related with the intensity of the liquid agitation and the generation of big size bubbles through bubble coalescence.
Geometry Effect of Multi-Walled Carbon Nanotube on Elastic Modulus of Polymer Composites
Suhr, Jonghwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 1, 2014, Pages 89~94
DOI : 10.3795/KSME-B.2014.38.1.089
The high Young's modulus and tensile strength of carbon nanotubes has attracted great attention from the research community given the potential for developing super-strong, super-stiff composites with carbon nanotube reinforcements. Over the decades, the strength and stiffness of carbon nanotube-reinforced polymer nanocomposites have been researched extensively. However, unfortunately, such strong composite materials have not been developed yet. It has been reported that the efficiency of load transfer in such systems is critically dependent on the quality of adhesion between the nanotubes and the polymer chains. In addition, the waviness and orientation of the nanotubes embedded in a matrix reduce the reinforcement effectiveness. In this study, we carried out performed micromechanics-based numerical modeling and analysis by varying the geometry of carbon nanotubes including their aspect ratio, orientation, and waviness. The results of this analysis allow for a better understanding of the load transfer capabilities of carbon nanotube-reinforced polymer composites.
Numerical Simulation of External Gear Pump Using Immersed Solid Method
Yoon, Yong Han ; Park, Byung Ho ; Han, Yong Oun ; Hong, Byeong Joo ; Shim, Jaesool ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 1, 2014, Pages 95~101
DOI : 10.3795/KSME-B.2014.38.1.095
In this study, an ISM (immersed solid method) was used for investigating the mass flow rate and efficiency of an involute-gear pump featuring very high rotational speed. For considering circulation flow at the gear pump and housing, fluid flow was assumed as turbulent, and the rotational speed of the gear pump increased under the condition of constant pressure at both the inlet and outlet. The efficiency and mass flow rate of the gear pump were studied by varying its rotational speed and the clearance between the gear tip and the housing. In the simulation results, as the rotational speed were increased, the average mass flow rate and efficiency increased. Furthermore, as the clearance between the gear tip and the housing was increased, the average mass flow rate and efficiency decreased. The efficiency was 85.11, 90.94, and 93.62 at rotational speeds of 6,000 rpm, 8,000 rpm, and 10,000 rpm, respectively, under the condition that there was no clearance. In addition, the efficiency was 93.62, 93.29, and 92.74 at clearances of 0 m, 0.00001 m, and 0.00003 m respectively.