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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
Editor in Chief :
Volume & Issues
Volume 26, Issue 12 - Dec 2002
Volume 26, Issue 11 - Nov 2002
Volume 26, Issue 10 - Oct 2002
Volume 26, Issue 9 - Sep 2002
Volume 26, Issue 8 - Aug 2002
Volume 26, Issue 7 - Jul 2002
Volume 26, Issue 6 - Jun 2002
Volume 26, Issue 5 - May 2002
Volume 26, Issue 4 - Apr 2002
Volume 26, Issue 3 - Mar 2002
Volume 26, Issue 2 - Feb 2002
Volume 26, Issue 1 - Jan 2002
Selecting the target year
Characteristic of Electric Generation for the Water Flow Rate in Thermoelctric Generator Using Hot Water
Woo, Byung-Chul ; Lee, Hee-Woong ; Suh, Chang-Min ;
Transactions of the Korean Society of Mechanical Engineers B, volume 26, issue 10, 2002, Pages 1333~1340
DOI : 10.3795/KSME-B.2002.26.10.1333
The objective of this study is to develop a thermoelectric generation system which converts unused energy from close-at-hand sources such as garbage incineration heat and industrial exhaust etc. into electricity. This paper presents applicability of a commercially available thermoelectric generator f3r waster heat recovery. The test facility consists of water heater, pump, thermoelectric module and aluminium tubes and hot and cold water is used as heat source and sink fluids. It is shown that the three components of thermoelectric research exist in manufacturing a thermoelectric generator. The first component is fabrication of thermoelectric materials, the second is manufacturing of thermoelectric generator with 32 thermoelectric modules. The last one is characteristic measuring of thermoelectric generator with 32 thermoelectric modules of two types, cooling and power purpose. It was found that the rate of cold and hot water is 25 and 37 liter per minute and the maximum power of thermoelectric generator is 28Watts and its efficiency is 1.04%.
Shape Optimization of Cut-Off in a Multi-blade Fan/Scroll System Using Neural Network
Han, Seog-Young ; Maeng, Joo-Sung ; Yoo, Dal-Hyun ; Jin, Kyong-Uk ;
Transactions of the Korean Society of Mechanical Engineers B, volume 26, issue 10, 2002, Pages 1341~1347
DOI : 10.3795/KSME-B.2002.26.10.1341
In order to improve efficiency of a system with three-dimensional flow characteristics, this paper presents a new method that overcomes three-dimensional effects by using two-dimensional CFD and neural network. The method was applied to shape optimization of cut-off in a multi-blade fan/scroll system. As the entrance conditions of two-dimensional CFD, the experimental values at the positions out of the inactive zone were used. The distributions of velocity and pressure obtained by two-dimensional CFD were compared with those of three-dimensional CFD and experimental results. It was found that the distributions of velocity and pressure have qualitative similarity. The results of two-dimensional CFD were used for teaming as target values of neural network. The optimal angle and radius of cut-off were determined as 71
and 0.092 times the outer diameter of impeller, respectively. It is quantified in the previous report that the optimal angle and radius of cut-off are approximately 72
and 0.08 times the outer diameter of impeller, respectively.
OH, PAHs and Soot Ditribution in a Laminar Diffusion Flame Under Oxidizer Deficient Ambience
Shim, Sung-Hoon ; Shin, Hyun-Dong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 26, issue 10, 2002, Pages 1348~1354
DOI : 10.3795/KSME-B.2002.26.10.1348
We investigate the flame behavior and spatial distribution of OH, PAHs and soot in a confined buoyant diffusion flame with decrease of the coflowing air flow rate. Direct photographs and Schlieren images represent that flame is Ally occupied by blue flame and becomes unstable, which is partially detached to the fuel nozzle tip in a near extinction flame under extremely reduced oxidizer condition. Laser induced fluorescence profiles clearly shows that OH is still generated in near-extinction flame, although intensity becomes weak with decreasing air flow rate. But soot scattering image cannot be seen any more in an oxidizer deficient ambience and simultaneously the PAHs are widely distributed downstream. These results are due to that a decrease of oxygen concentration in the combustion chamber leads to a temperature drop of flame, as a consequence, to a delay in soot growth and to a expanding of the PAHs, as soot precursors.
An Experimental Study About Interaction of Droplet Array Combustion
Kim, Heung-Sik ; Baek, Seung-Wook ; Park, Jun-Sung ;
Transactions of the Korean Society of Mechanical Engineers B, volume 26, issue 10, 2002, Pages 1355~1363
DOI : 10.3795/KSME-B.2002.26.10.1355
An experimental study was conducted to investigate the interaction phenomena of droplet array combustion in ambient environment. The droplet with 1 mm in diameter was supported from an optical fiber and ignited with a hot wire. Combustion lifetimes and burning rate constants were measured for fuel of nheptane according to parameters, which were junction and suspender spacings, and array configuration. Results show that the burning process considerably depends on the initial away configuration. The d
-law is found to be correct when applied to both of the droplets in away and the single droplet. For separation distance of about 5mm, there exists a critical state. So the transition from a merged flame to separated flames occurs and burning velocity is much faster than before. Combustion lifetime of the lower droplet is shorter than that of the upper droplet in the two-dimensional arrays combustion. Burning rate constants of the droplets in arrays are smaller than that of the single droplet, while they become higher as separation distance increases. Combustion lifetimes of the droplets in arrays are longer than that of the single droplet and decrease as separation distance increase. It is concluded that the array configuration and the mergedness of the flame are the most important factors governing multi-droplet combustion.
Development of Integrated Valve Train System Design Program
Transactions of the Korean Society of Mechanical Engineers B, volume 26, issue 10, 2002, Pages 1364~1369
DOI : 10.3795/KSME-B.2002.26.10.1364
This paper introduces the development of the analysis and design program of valve train system. In order to verify the stability of design and improve the performance of system efficiently, it is required that integrated and interactive simulation program. The presented program is developed in the base of the object-oriented, capsulation, modulization, OLE (objected linking and embedding) and various design theory. It contains the expandability and flexibility of the structure. In addition to that, it is programmed to make the convenient user interface by using the visualization programming. This program can support the modification of the valve element as well as the development of the valve train system in the beginning of design. It is expected to save the cost and time for the design of valve train system.
Performance Design Analysis of the Supercritical Pressure Bottoming System of Combined Cycle Power Plants Using Once-Through Steam Generator
Transactions of the Korean Society of Mechanical Engineers B, volume 26, issue 10, 2002, Pages 1370~1377
DOI : 10.3795/KSME-B.2002.26.10.1370
This study analyzed the design performance of the bottoming system of combined cycle power plants using a once-through heat recovery steam generator. For a parallel arrangement of the main heater and reheater, parametric analyses were carried out to present the criteria for determining the reheater pressure and the location of the starting point of the reheater in the HRSG. The performance of the bottoming system was presented fer a range from high subcritical to supercritical pressure. The steam turbine power is as high as that of conventional triple-pressure bottoming systems. The serial arrangement of heat exchangers with division of each heater into several segments can achieve similar power level.
Velocity Profile and Wall Shear Stress Distributions of Developing Turbulent Oscillatory Flows in an Oscillator Connected to Straight Duct Located in Exit Region of a Curved Duct
Transactions of the Korean Society of Mechanical Engineers B, volume 26, issue 10, 2002, Pages 1378~1386
DOI : 10.3795/KSME-B.2002.26.10.1378
In the present study, velocity profile and wall shear stress distributions of developing turbulent oscillatory flows in an oscillator connected to straight duct located in exit region of a curved duct was investigated experimentally. The experimental study for air flows was conducted to measure axial velocity profiles, shear stress distributions by using the Laser Doppler Velocimetry(LDV) system with the data acquisition and processing system of Rotating Machinery Resolver(R.M.R) and PHASE software. The results obtained from experimental studies are summarized as follows. The critical Reynolds number for a change from transitional oscillatory flow to turbulent flow was about 7500, in the 60region of dimensionless axial position which was considered as a fully developed flow region. The turbulent oscillatory flow, velocity profiles of the inflow period in the entrance region were gradually developed, but those of the outflow period were not changed nearly. Velocity profiles of inflow and outflow were shown as a symmetric form in a fully developed flow region. The wall shear stress distributions of turbulent oscillatory flow increase rapidly as the flow proceeds to downstream and flow was in good agreement with the theoretically.
Flame Structure of Moderately Turbulent Combustion in the Opposed Impinging Jet Combustor
Transactions of the Korean Society of Mechanical Engineers B, volume 26, issue 10, 2002, Pages 1387~1393
DOI : 10.3795/KSME-B.2002.26.10.1387
The measurement of velocity and stain rate field has been conducted in opposed impinging jet combustion. When a smaller diameter (5mm) orifice of pre-chamber was used, previous studies had reported that the combustion phase showed a shift from weak turbulent combustion to moderate turbulent combustion in the modified Borghi Diagram. In the case with smaller orifice diameter (5mm), NOx emission was substantially reduced by a factor 1/2 while the combustion pressure remains at the same as that in the conventional combustion. Hence, in this study, the experiment setup using PIV technique was designed to identify the relation of the strain rate distribution and NOx reduction associated with moderate turbulent combustion. As a result, it was found that the highly strained pockets are widely distributed during the combustion in the middle of chamber when the orifice diameter is 5mm. And the corresponding PDF distribution of strain rates she was the smoothly distributed strain .ate within the range of ｜
1000｜ (1/sec) rather than a spike shape about zero point. This is the unique feature observed in the combustion with 5mm orifice diameter. Therefore, it can be concluded that the substantial NOx reduction in opposed impinging combustor is mainly attributed to the strain rate distribution within the range of ｜
1000｜resulting in the combustion phase shift to moderate turbulent combustion.
Performance Analysis of a Linear Micro-actuator Operated by Radiometric Phenomena in Rarefied Gas Flow Field
Transactions of the Korean Society of Mechanical Engineers B, volume 26, issue 10, 2002, Pages 1394~1405
DOI : 10.3795/KSME-B.2002.26.10.1394
The performance of micro-actuators utilizing radiometric forces are studied numerically. The Knudsen number based on gas density and characteristic dimension is varied from near-continuum to highly rarefied conditions. Direct simulation Monte Carlo(DSMC) calculations have been performed to estimate the performance of the micro-actuators. In the present DSMC method, the variable hard sphere molecular model and no time counter technique are used to simulate the molecular collision kinetics. For simulation of diatomic gas flows, the Borgnakke-Larsen phenomenological model is adopted to redistribute the translational and internal energies.
Effects of Nozzle Locations on the Rarefied Gas Flows and Al Etch Rate in a Plasma Etcher
Transactions of the Korean Society of Mechanical Engineers B, volume 26, issue 10, 2002, Pages 1406~1418
DOI : 10.3795/KSME-B.2002.26.10.1406
The direct simulation Monte Carlo(DSMC) method is employed to calculate the etch rate on Al wafer. The etchant is assumed to be Cl
. The etching process of an Al wafer in a helicon plasma etcher is examined by simulating molecular collisions of reactant and product. The flow field inside a plasma etch reactor is also simulated by the DSMC method fur a chlorine feed gas flow. The surface reaction on the Al wafer is simply modelled by one-step reaction: 3C1
. The gas flow inside the reactor is compared for six different nozzle locations. It is found that the flow field inside the reactor is affected by the nozzle locations. The Cl
number density on the wafer decreases as the nozzle location moves toward the side of the reactor. Also, the present numerical results show that the nozzle location 1, which is at the top of the reactor chamber, produces a higher etch rate.
A Study on Critical Heat Elux Characteristics in a Two-Phase Concentric-Tube Thermosyphon
Transactions of the Korean Society of Mechanical Engineers B, volume 26, issue 10, 2002, Pages 1419~1426
DOI : 10.3795/KSME-B.2002.26.10.1419
An experimental study was made to elucidate critical heat flux(CHF) characteristics in a two-phase concentric-tube thermosyphon. The experiment was performed by using saturated water, over the experimental range of configuration: inner diameter of heated outer tube D
Numerical Analysis on Heat Transfer Characteristics in Silicon Boated by Picosecond-to-Femtosecond Ultra-Short Pulse Laser
Transactions of the Korean Society of Mechanical Engineers B, volume 26, issue 10, 2002, Pages 1427~1435
DOI : 10.3795/KSME-B.2002.26.10.1427
The main aim of the present article is numerically to investigate the micro-scale heat transfer phenomena in a silicon microstructure irradiated by picosecond-to-femtosecond ultra-short laser pulses. Carrier-lattice non-equilibrium phenomena are simulated with a self-consistent numerical model based on Boltzmann transport theory to obtain the spatial and temporal evolutions of the lattice temperature, the carrier number density and its temperature. Especially, an equilibration time, after which carrier and lattice are in equilibrium, is newly introduced to quantify the time duration of non-equilibrium state. Significant increase in carrier temperature is observed for a few picosecond pulse laser, while the lattice temperature rise is relatively small with decreasing laser pulse width. It is also found that the laser fluence significantly affects the N 3 decaying rate of Auger recombination, the carrier temperature exhibits two peaks as a function of time due to Auger heating as well as direct laser heating of the carriers, and finally both laser fluence and pulse width play an important role in controlling the duration time of non-equilibrium between carrier and lattice.
A Study on the Development of a Three Dimensional Numerical Model for the Casting Processes
Transactions of the Korean Society of Mechanical Engineers B, volume 26, issue 10, 2002, Pages 1436~1444
DOI : 10.3795/KSME-B.2002.26.10.1436
A three dimensional numerical model was developed to analyze the mold filling and solidification processes straightforwardly in a casting processes. On the basis of the SIMPLER algorithm, the VOF method and the Equivalent Specific Heat method were adopted to deal with the free surface behavior and the latent heat evolution. The complete model has been validated using exact solutions and experimental results. The importance of three-dimensional effects has been highlighted by comparing the results from the three-dimensional analysis with those given by a two-dimensional analysis.
Development of Image Processing Algorithm Using Boundary Curvature Information in Particle Size Measurement
Transactions of the Korean Society of Mechanical Engineers B, volume 26, issue 10, 2002, Pages 1445~1450
DOI : 10.3795/KSME-B.2002.26.10.1445
In the present study, a new pattern recognition algorithm was proposed to size spray particles using the boundary curvature information. Conceptually, this algorithm has an advantage over the others because it can identify the particle size and shape simultaneously, and also can separate the overlapped particles more effectively. Curvature of a boundary was obtained from the change of the slopes of two neighboring segments at the corresponding part. The algorithm developed in this study was tested by using an artificially prepared image of a group of spherical particles which were either isolated or overlapped. Particle sizes obtained from the measured curvatures agreed well with the true values. By detecting abrupt changes of the curvature along the image boundary, the element particles could be separated out from their overlapped images successfully.
Effect of Nozzle Material on Drop Size Distribution in Electrohydrodynamic Spraying
Transactions of the Korean Society of Mechanical Engineers B, volume 26, issue 10, 2002, Pages 1451~1457
DOI : 10.3795/KSME-B.2002.26.10.1451
When an aqueous liquid such as water having high electric conductivity and high surface tension is discharged from a nozzle under a strong DC electric field, fine drops ranging from 30 to 450 microns can be obtained only through the spindle mode. In the present study, effects of the electric conductivity and the surface wettability of nozzle materials on formation of drops with this mode were investigated. For that, three nozzles with the same size but with different materials were prepared and tested; a stainless steel needle, and a plain and a metal (gold)-coated (except for the tip portion) silica needles. Uniform drops were obtained with the gold-coated silica nozzle over the wider range of the DC voltage input. That is, formation of the liquid cone and detachment of the liquid spindle (ligament) can be more stabilized and frequent with the needles having high electric conductivity but with low surface wettability at their tips.
Effect of Diluents and Oxygen-Enrichness on the Stability of Nonpremixed Flame
Transactions of the Korean Society of Mechanical Engineers B, volume 26, issue 10, 2002, Pages 1458~1464
DOI : 10.3795/KSME-B.2002.26.10.1458
is well known greenhouse gas which is the major source of global warming. Reducing
emission in combustion process can be achieved by increasing combustion efficiency, oxygen enriched combustion and recirculation of the emitted
gas. Stability of non-premixed flame in oxygen enriched environment will be affected by the amount of oxygen, kind of diluents and fuel exit velocity. The effects of these parameters on flame liftoff and blowout are studied experimentally oxidizer coflowing burner. Experiments were divided into three cases according as where
gas was supplied. - 1) to coflowing air, 2) to fuel with 0
coflow, 3) to coflowing oxygen. Flame in air coflowing case was lifted in turbulent region. Flame lift and blowout in laminar region with the increase in
volume fraction in
-Air mixture makes flame lift and blowout in laminar region. Increase in oxygen volume fraction makes flame stable-i.e. flame liftoff and blowout occur at higher fuel flowrates. Liftoff height was non-linear function of nozzle exit velocity and affected by the
volume fraction. It was found that the flame in
coflow case was more stable than
case, Liftoff heights vs (nozzle exit velocity/laminar burning velocity)
has a good correlation in
An Experimental Study on a Simultaneous Determination of Reference Free-Stream Temperature and Convective Heat Transfer Coefficients
Transactions of the Korean Society of Mechanical Engineers B, volume 26, issue 10, 2002, Pages 1465~1471
DOI : 10.3795/KSME-B.2002.26.10.1465
This paper deals with the development of a new method that can obtain the heat transfer coefficient and the reference free stream temperature simultaneously. The method is experimentally verified through comparison with results in convective heat transfer experiments of a circular impinging jet using two narrow-band TLCs. The general method described in this paper is highly recommended to many heat transfer models with the unknown or ambiguous free stream temperature.
The Emission Characteristics of a 4-stroke Large Diesel Engines for Propulsion and Generation Application in IMO modes
Transactions of the Korean Society of Mechanical Engineers B, volume 26, issue 10, 2002, Pages 1472~1479
DOI : 10.3795/KSME-B.2002.26.10.1472
Environmental protection on the ocean has been interested and nowadays the International Maritime Organization(IMO) has advanced on the prevention of air pollution from ships. This study presents the emission characteristics of 4 stroke marine diesel engines in E3 cycle (propulsion application) and D2 cycle (generation application). Also the effects of important operating parameters in terms of intake air pressure and temperature, and maximum combustion pressure on the specific emissions are described. Emissions measurement and calculation are processed according to IMO Technical Code. The results show that NOx emission level in E3 cycle is higher than that in D2 cycle due to lower engine speed at low load and the maximum combustion pressure by fuel injection timing control and intake air temperature has strong influence on NOx emission production. And CO, HC emissions are not affected by maximum combustion pressure and intake air pressure and temperature.