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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 35, Issue 12 - Dec 2011
Volume 35, Issue 11 - Nov 2011
Volume 35, Issue 10 - Oct 2011
Volume 35, Issue 9 - Sep 2011
Volume 35, Issue 8 - Aug 2011
Volume 35, Issue 7 - Jul 2011
Volume 35, Issue 6 - Jun 2011
Volume 35, Issue 5 - May 2011
Volume 35, Issue 4 - Apr 2011
Volume 35, Issue 3 - Mar 2011
Volume 35, Issue 2 - Feb 2011
Volume 35, Issue 1 - Jan 2011
Selecting the target year
Development of a Cooling System for a Concentrating Photovoltaic Module
Kim, Tae-Hoon ; Do, Kyu-Hyung ; Choi, Byung-Il ; Han, Yong-Shik ; Kim, Myung-Bae ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 6, 2011, Pages 551~560
DOI : 10.3795/KSME-B.2011.35.6.551
In this paper, a cooling system that includes a heat spreader and a natural convective heat sink is proposed for the cooling of a concentrating photovoltaic (CPV) module. The heat spreader and the natural convective heat sink are designed on the basis of previous analytical investigations. In order to evaluate the proposed cooling system, we conducted experimental investigations varying the heat rate and the inclined angle of the cooling system. From the experimental results, it is found that the proposed cooling system satisfies the design constraints for good operation of the CPV module. Finally, a correlation is suggested for estimating the effects of the heat rate and the inclined angle on the thermal performance of the natural convective heat sink is suggested.
Inverse Radiation Analysis of a Two-Dimensional Irregular Geometry Using Unstructured Triangular Meshes
Yi, Kyung-Joo ; Baek, Seung-Wook ; Kim, Man-Young ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 6, 2011, Pages 561~567
DOI : 10.3795/KSME-B.2011.35.6.561
The inverse radiation analysis of a two-dimensional irregular configuration using unstructured triangular meshes is presented. In this study, an enclosure filled with an absorbing, emitting and scattering medium with diffusely emitting and reflecting opaque boundaries is considered. The finite volume method is applied to solve the radiative transfer equation in order to simulate the measured incident radiation values which are used as input data for the inverse analysis. The conjugate gradient method is adopted for the estimation of wall emissivities by minimizing the objective function at each iteration step. To verify the performance of the unstructured grid system, we compare the results with those using a structured grid system for the two-dimensional lopsided shape. The effect of measurement errors on the estimation accuracy is also investigated.
Study on Thermal Performance of Multiple LED Packages with Heat Pipes
Hwang, Soon-Ho ; Lee, Young-Lim ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 6, 2011, Pages 569~575
DOI : 10.3795/KSME-B.2011.35.6.569
Since the high heat generation of LED chips can cause a reduction in lifetime, degradation of luminous efficiency, and variation of color temperature, studies have been carried out on the optimization of LED packaging and heat sinks. Recently, LED packages have been applied to high-power lights such as car headlamps or street lights, and it is known that cooling using only free convection is not at all efficient. Thus, in this study, a heat pipe with forced convection was examined for the optimization of the cooling performance in high-power LED lights. In addition, optimal on-off control of a fan was adopted to increase the fan lifetime, since the lifetime of the fan is generally shorter than that of the LEDs.
A Study of the Reduction of Diesel-Engine Emissions for Off-Road Vehicles
Cho, Gyu-Baek ; Kim, Hong-Suk ; Kang, Jeong-Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 6, 2011, Pages 577~583
DOI : 10.3795/KSME-B.2011.35.6.577
To meet the requirements of the Tier 4 interim regulations for off-road vehicles, emissions of particulate matter (PM) and nitrogen oxides (NOx) must be reduced by 95% and 30%, respectively, compared to current regulations. In this research, both the DPF and HPL EGR systems were investigated, with the aim of decreasing the PM and NOx emissions of a 56-kW off-road vehicle. The results of the experiments show that the DOC-DPF system is very useful for reducing PM emissions. It is also found that the back pressure is acceptable, and the rate of power loss is less than 5%. By applying the HPL EGR system to the diesel engine, the NOx emissions under low- and middle-load conditions are reduced effectively because of the high differential pressure between the turbocharger inlet and the intake manifold. The NOx emissions can be decreased by increasing the EGR rate, but total hydrocarbon (THC) emission increases because of the increased fuel consumption needed to compensate for the power loss caused by EGR and DPF.
An Experimental Study of Synthesis and Characterization of Vanadium Oxide Thin Films Coated on Metallic Bipolar Plates for Cold-Start Enhancement of Fuel Cell Vehicles
Jung, Hye-Mi ; Noh, Jung-Hun ; Im, Se-Joon ; Lee, Jong-Hyun ; Ahn, Byung-Ki ; Um, Suk-Kee ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 6, 2011, Pages 585~592
DOI : 10.3795/KSME-B.2011.35.6.585
The enhancement of the cold-start capability of polymer electrolyte fuel cells is of great importance in terms of the durability and reliability of fuel-cell vehicles. In this study, vanadium oxide films deposited onto the flat surface of metallic bipolar plates were synthesized to investigate the feasibility of their use as an efficient self-heating source to expedite the temperature rise during startup at subzero temperatures. Samples were prepared through the dip-coating technique using the hydrolytic sol-gel route, and the chemical compositions and microstructures of the films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and field-emission scanning electron microscopy. In addition, the electrical resistance hysteresis loop of the films was measured over a temperature range from -20 to
using a four-terminal technique. Experimentally, it was found that the thermal energy (Joule heating) resulting from self-heating of the films was sufficient to provide the substantial amount of energy required for thawing at subzero temperatures.
The Effect of Thermal Management on the Performance of a Polymer Electrolyte Membrane Fuel Cell System
Lee, Jeong-Ho ; Myung, No-Sung ; Kim, Tong-Seop ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 6, 2011, Pages 593~601
DOI : 10.3795/KSME-B.2011.35.6.593
An analysis program to simulate the operation of a polymer electrolyte membrane fuel cell (PEMFC) system was set up, and system operation with variations in the working conditions of various components (especially the thermal management system) was simulated. The entire system included a PEMFC stack and balance-of-plant components such as an air-supply unit, a fuel-supply unit, and a heat-management unit (cooling system). Thermodynamic models of all components were made to evaluate the design performance of the entire system, and then off-design models were set up to simulate the operation of the entire system under arbitrary working conditions. A parametric study was carried out to examine the effects of varying the operating conditions (especially the ambient conditions and the operating conditions of the cooling system) on the operation and performance of the entire system.
Hybrid Particle Image Velocimetry Based on Affine Transformation
Doh, Deog-Hee ; Cho, Gyong-Rae ; Lee, Jae-Min ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 6, 2011, Pages 603~608
DOI : 10.3795/KSME-B.2011.35.6.603
Since PTV (particle tracking velocimetry) provides velocity vectors by tracking each particle in a fluid flow, it has significant benefits when used for nano- and bio-fluid flows. However, PTV has only been used for limited flow fields because interpolation data loss is inevitable in PTV in principle. In this paper, a hybrid particle image velocimetry (PIV) algorithm that eliminates interpolation data loss was constructed by using an affine transformation. For the evaluation of the performance of the constructed hybrid PIV algorithm, an artificial image test was performed using Green-Taylor vortex data. The constructed algorithm was tested on experimental images of the wake flow (Re = 5,300) of a rectangular body (
), and was demonstrated to provide excellent results.
Study of Stokes Flow Past a Vertical Plate in a Two-Dimensional Channel
Yoon, Seok-Hyun ; Jeong, Jae-Tack ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 6, 2011, Pages 609~615
DOI : 10.3795/KSME-B.2011.35.6.609
A two-dimensional Stokes flow past a vertical plate in a channel is analyzed. The vertical plate is located at the center of the channel, and plane Poiseuille flow exists far upstream and downstream of the vertical plate. The Stokes approximation is used, and the flow is investigated analytically using the method of eigenfunction expansion and the point collocation method. From the analysis, the stream function and pressure distribution are obtained, and the pressure and shear stress distributions on the plate and channel wall are calculated. The additional pressure drop induced by the vertical plate and the force exerted on it are calculated as functions of the length of the vertical plate. For a typical length of the vertical plate, the streamline pattern and pressure distribution are shown. In addition, numerical analysis of laminar flow with a small Reynolds number is carried out to analyze the effect of a small Reynolds number on the flow pattern.
Study of Sloshing Flow in a Rectangular Tank
Ji, Young-Moo ; Shin, Young-Seop ; Park, Jun-Sang ; Hyun, Jae-Min ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 6, 2011, Pages 617~624
DOI : 10.3795/KSME-B.2011.35.6.617
The two-dimensional sloshing problem in a rigid rectangular tank with a free surface is considered. The flow is generated by a container in harmonic motion in time along the horizontal axis, i.e., a container excited by u=Asin(
) where u denotes the container velocity imposed externally, A is the amplitude of the oscillation velocity, and f is the frequency of oscillation. Experimental apparatus is arranged to investigate the large-amplitude sloshing flows in off-resonant conditions, where the large amplitude means that A~O(1), and the distance, S, is comparable to the breadth, L, of the container, i.e., L/S~O(1). Comprehensive particle image velocimetry (PIV) data are obtained, which show that the flow physics of the nonlinear off-resonant sloshing problem can be characterized into three peculiar free surface motions: standing-wave motions similar to those of linear sloshing, a run-up phenomenon along the vertical sidewall at the moment of turn-over of the container, and gradually propagating bore motion from the sidewall to the interior fluid region, like a hydraulic jump.
Study of Ignition Characteristics of CH
/Hot Air Diffusion Flame Using a Flame-Controlling Continuation Method
Song, Keum-Mi ; Oh, Chang-Bo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 6, 2011, Pages 625~632
DOI : 10.3795/KSME-B.2011.35.6.625
The ignition characteristics of a
/hot air counterflow diffusion flame were investigated numerically using a flame-controlling continuation method. For the chemical reactions, the GRI-v1.2 reaction mechanism was used in the simulation. The maximum flame temperature was presented in the space of the inverse global strain rate, and showed S-curve-type behavior. The flame temperatures and velocities of the upper and middle branches were compared for different global strain rates. In addition, the global strain rate was compared with the local strain rates defined at the flame surface and the boundaries of the fuel and oxidizer sides of the fuel/air mixing layer. These local strain rates correlated well with the global strain rate.
Basic Experimental Study of the Edge-Flame Intensity Variation at High Temperature and with Small Fuel-Concentration Gradient
Lee, Min-Jung ; Kim, Nam-Il ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 6, 2011, Pages 633~640
DOI : 10.3795/KSME-B.2011.35.6.633
In this study, the stabilization of an edge flame and the intensity variation of a diffusion branch were investigated using a multi-slot combustor under conditions of high temperature and small fuel-concentration gradient (FCG). The combustor consists of three narrow channels: a quartz channel and two side-heating combustors. For the accuracy of this experimental study, quantitative analysis was carried out for each boundary condition. Stable edge flames could be observed under high-temperature conditions by controlling the FCG and fuel dilution ratio. Moreover, it was found that the intensity of the diffusion flame was increased by increasing the temperature of the mixture. On the contrary, the intensity of the diffusion flame was decreased by increasing the dilution ratio. It was also found that a propane flame is more sensitively affected by these experimental parameters than a methane flame.
Thermal Behaviors and Reaction Characteristics of an Integrated Reactor with Catalytic Combustion-Reforming According to Operation Conditions
Ghang, Tae-Gyu ; Lee, Sang-Min ; Ahn, Kook-Young ; Kim, Yong-Mo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 6, 2011, Pages 641~648
DOI : 10.3795/KSME-B.2011.35.6.641
Off-gases emitted from the anode of a molten carbonate fuel cell (MCFC) at high temperatures for power generation are used as fuel in catalytic combustion. The heat generated in the catalytic combustor is utilized as the heat for the endothermic reaction required for steam reforming. Among the various operational conditions of the integrated reactor, we varied the inlet gas compositions of the catalytic combustor according to fuel utilization in the MCFC and the ratio of steam to carbon in the reformer. Subsequently, the thermal behaviors and reaction characteristics of the integrated reactor were investigated experimentally. The fundamental data from this experimental study will be useful for the design and fabrication of a more practical integrated reactor in the future.
Numerical Simulation of Lithium-Ion Batteries for Electric Vehicles
You, Suk-Beom ; Jung, Joo-Sik ; Cheong, Kyeong-Beom ; Go, Joo-Young ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 6, 2011, Pages 649~656
DOI : 10.3795/KSME-B.2011.35.6.649
A model for the numerical simulation of lithium-ion batteries (LIBs) is developed for use in battery cell design, with a view to improving the performances of such batteries. The model uses Newman-type electrochemical and transfer
to describe the behavior of the lithium-ion cell, together with the Levenberg-Marquardt optimization scheme to estimate the performance or design parameters in nonlinear problems. The mathematical model can provide an insight into the mechanism of LIB behavior during the charging/discharging process, and can therefore help to predict cell performance. Furthermore, by means of least-squares fitting to experimental discharge curves measured at room temperature, we were able to obtain the values of transport and kinetic parameters that are usually difficult to measure. By comparing the calculated data with the life-test discharge curves (SB LiMotive cell), we found that the capacity fade is strongly dependent on the decrease in the reaction area of active materials in the anode and cathode, as well as on the electrolyte diffusivity.