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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers A
Journal Basic Information
Journal DOI :
The Korean Society of Mechanical Engineers
Editor in Chief :
Volume & Issues
Volume 32, Issue 12 - Dec 2008
Volume 32, Issue 11 - Nov 2008
Volume 32, Issue 10 - Oct 2008
Volume 32, Issue 9 - Sep 2008
Volume 32, Issue 8 - Aug 2008
Volume 32, Issue 7 - Jul 2008
Volume 32, Issue 6 - Jun 2008
Volume 32, Issue 5 - May 2008
Volume 32, Issue 4 - Apr 2008
Volume 32, Issue 3 - Mar 2008
Volume 32, Issue 2 - Feb 2008
Volume 32, Issue 1 - Jan 2008
Selecting the target year
Stability Improvement of the Ultra-High Speed Micro Turbocharger Supported by Air Foil Bearings
Kwak, Yong-Suk ; Kim, Chang-Ho ; Chung, Jin-Taek ; Lee, Yong-Bok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 7, 2008, Pages 541~548
DOI : 10.3795/KSME-A.2008.32.7.541
To improve the operational stability of the 100 Watts class Micro Gas Turbine, the air foil bearing with additional damping material has been investigated. The key of structure is that a viscoelastic material is coated under the top foil. The compliant foil journal bearing and thrust bearing are designed to withstand high load of vibrations at the operational speed 870,000 rpm. Test is executed in room temperature. Rotor has stably operated above 480,000 rpm. It is over 55% of the designed speed 870,000 rpm. Synchronous and subsynchronous vibrations are both well controlled. Vibration amplitude diminished over 50%. With the help of increased damping resulting from the viscoelasticity, the rotor stability of Micro turbocharger has been improved.
Analytical Method to Analyze the Tolerance Effect on the Vehicle Ride Comfort
Kim, Beom-Seok ; Yoo, Hong-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 7, 2008, Pages 549~555
DOI : 10.3795/KSME-A.2008.32.7.549
Analytical method to analyze the tolerance effect on the vehicle ride comfort is suggested in this paper. Ride comfort is one of the most important performance indices which decide the vehicle design quality. In general, the ride comfort is affected by the variations of parameters of a vehicle model. Therefore, the effects of the parameters on the ride comfort need to be evaluated statistically based on the whole-body vibration of the vehicle. In this paper, weighted RMS values of the acceleration PSD of a seat position are used to define the ride comfort. The equations of motion and the sensitivity equations are derived based on a 5-DOF vehicle model. By employing the sensitivity information of the acceleration at the seat position, the tolerance effect on the vehicle ride comfort could be effectively analyzed.
A Fault Diagnosis on the Rotating Machinery Using Mahalanobis Distance
Park, Sang-Gil ; Park, Won-Sik ; Jung, Jae-Eun ; Lee, You-Yub ; Oh, Jae-Eung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 7, 2008, Pages 556~560
DOI : 10.3795/KSME-A.2008.32.7.556
As higher reliability and accuracy on production facilities are required to detect incipient faults, a diagnostic system for predictive maintenance of the facility is highly recommended. In this paper, we present a study on the application of vibration signals to diagnose faults for a Rotating Machinery using the Mahalanobis Distance-Taguchi System. RMS, Crest Factor and Kurtosis that is known as the Statistical Methods and the spectrum analysis are used to diagnose faults as parameters of Mahalanobis distance.
A Study on the Quantitative Assessment Method for Shift Quality of Automatic Transmission in a Wheel Loader
Lee, Jong-Chan ; Kim, Kwan-Soo ; Yim, Jong-Hyung ; Lee, Hyo-Won ; Kwon, Young-Min ; Kim, Hyung-Jun ; Lee, Min-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 7, 2008, Pages 561~568
DOI : 10.3795/KSME-A.2008.32.7.561
The quality of the automatic transmission shift for a wheel loader has been generally evaluated by driver's perception. However the subjective evaluation of the drivers is not always directly related to the shift quality. It is necessary to set up the method for an objective assessment of the shift quality. In this paper, a quantitative assessment method has been developed for the shift quality of the automatic transmission in a wheel loader. The indices for the evaluation were selected through the various tests like the acceleration and the turbine rpm as well as the subjective evaluation of the driver, and were validated by the correlation between subjective and objective assessments using a psychophysical power law. Based on this method, the shift quality of a wheel loader has been evaluated quantitatively under various shift conditions.
Evaluation of Bond Strength of Isothermally Aged Plasma Sprayed Thermal Barrier Coating
Kim, Dae-Jin ; Lee, Dong-Hoon ; Koo, Jae-Mean ; Song, Sung-Jin ; Seok, Chang-Sung ; Kim, Mun-Young ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 7, 2008, Pages 569~575
DOI : 10.3795/KSME-A.2008.32.7.569
In this study, disk type of thermal barrier coating system for gas turbine blade was isothermally aged in the furnace changing exposure time and temperature. For each aging condition, bond tests for three samples were conducted for evaluating degradation of adhesive or cohesive strength of thermal barrier coating system. For as-sprayed condition, the location of fracture in the bond test was in the middle of epoxy which have bond strength of 57 MPa. As specimens are degraded by thermal aging, bond strength gradually decreased and the location of failure was also changed from within top coat at the earlier stage of thermal aging to the interface between top coat and TGO at the later stage due to the delamination in the coating.
Design of Visualization System for Stress Evaluation of Elastic Wave
Nam, Young-Hyun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 7, 2008, Pages 576~582
DOI : 10.3795/KSME-A.2008.32.7.576
This paper describes a synthesized photoelastic method developed for the visualization and evaluation of sound pressure distribution of elastic wave in a solid. The visualization of wave stress field is achieved by synthesizing two photoelastic pictures, in which the direction of the principal axis of linear polariscopes differs by
. From the analysis of the wave stress distribution using this method, it is possible to evaluate the characteristics of elastic waves in a solid, such as the intensity of stress, directivity and resolution characteristics of the wave emitted from a commercial probe, and characteristics of scattering from various types of defects.
A Study on Damage Evaluation of Bearings for Rotating Machinery in Power Plant Using Ultrasonic Wave
Lee, Sang-Guk ; Lee, Sun-Ki ; Lee, Do-Hwan ; Park, Sung-Keun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 7, 2008, Pages 583~589
DOI : 10.3795/KSME-A.2008.32.7.583
For the purpose of monitoring by ultrasonic test of the ball bearing conditions in rotating machinery, a system for their diagnosis was developed. ultrasonic technique is used to detect abnormal conditions in the bearing system. And various data such as frequency spectrum, energy and amplitude of ultrasonic signals, and ultrasonic parameters were acquired during experiments with the simulated ball bearing system. Based on the above results and practical application for power plant, algorithms and judgement criteria for diagnosis system was established. Bearing diagnosis system is composed of four parts as follows : sensing part for ultrasonic sensor and preamplifier, signal processing part for measuring frequency spectrum, energy and amplitude, interface part for connecting ultrasonic signal to PC using A/D converter, graphic display and software part for display of bearing condition and for managing of diagnosis program.
Elastic Modulus Prediction for Design of Sintered Aluminum by Ultrasonic
Nam, Young-Hyun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 7, 2008, Pages 590~596
DOI : 10.3795/KSME-A.2008.32.7.590
The ultrasonic velocities of sintered aluminum with varying density were measured in order to deduce the mechanical properties for optimum design of the sintered aluminum. Specimens with different densities were prepared by the plasma activated sintering machine. The density distribution of sintered aluminum becomes partially inhomogeneous because of the friction between the powder and the die during compaction. The elastic moduli are increased as the ultrasonic velocity is increased. Furthermore, Poisoon's ratio is depending on not only the density but also the size and distribution of voids. As the specimen's thickness increases, the center frequency in the frequency spectrum of the reflection wave is shifted to the low frequency. The attenuation coefficient of ultrasonic wave is decreased inversely as the density increased.
The Strain Measurement of One Point Spot Welded Zone Using the 3-D ESPI
Cha, Y.H. ; Kang, D.J. ; Jang, H. ; Jang, K.C. ; Sung, S.B. ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 7, 2008, Pages 597~601
DOI : 10.3795/KSME-A.2008.32.7.597
Currently knowledge of strain in welds has mainly been obtained from strain gaging method: that is directly attaching most of the material to the gage. The very few non-contact methods are still in the early stage. One of the non-contact methods is by the use of the laser that has high-level of the accuracy for the measurement, and this laser also has excellent characteristics on which many studies for its applications are focused throughout the many fields. A method of study is on the measurement of the strain caused by the characteristics of the spot welded zone which is used with 3-D ESPI system that is functionally modified through the laser ESPI(Electronic Speckle Pattern Interferometry) system. This system employed the SGCC 1.2t which are mainly used for the steel plate such as automobile, structure, building material and electronic appliances.
Process Optimization of Industrial Solid Freeform Fabrication System
Kwak, Sung-Jo ; Lee, Doo-Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 7, 2008, Pages 602~609
DOI : 10.3795/KSME-A.2008.32.7.602
This paper presents experimental optimization of process parameters for a newly developed SFF(Solid Freeform Fabrication) system. Two critical process parameters, layering thickness and curing period, which have a large effect on the quality of the product, are optimized through experiments. Specimens are produced using layering thicknesses of 60, 80, 100, 120, 140, and
and curing periods of 0, 10, 20, and 30 minutes under the same processing conditions, i.e., build-room temperature, feed-room temperature, roller speed, laser power, scan speed, and scan spacing. The specimens are tested to compare and analyze performance indices such as thickness accuracy, flatness, stress-strain characteristics, and porosity. The experimental result indicates that layering thickness of
and curing period of
minutes are recommended for the developed industrial SFF system.
A Study on the Safety of TBP(150A) with Forming Analysis and Strength Test
Lee, Sung-Ho ; Kim, Hei-Song ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 7, 2008, Pages 610~616
DOI : 10.3795/KSME-A.2008.32.7.610
For this study, the forming analyses and body strength tests of TBP were performed on the main pipe size 150A(KS D3507, KS D 3576 10S). The branched pipe sizes utilized were 25A, 32A, 40A, 50A, 65A, 80A, 100A and 125A. A general FEM program, ABAQUS, was used as the forming analyses method of TBP. Using the results, the strength of TBP was then tested in order to determine the safety of TBP when the working pressure was applied. The results indicate that TBP may be safely used in water-based fire protection pipe systems in terms of the strength.