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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
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Journal DOI :
The Korean Society of Mechanical Engineers
Editor in Chief :
Volume & Issues
Volume 21, Issue 12 - Dec 1997
Volume 21, Issue 11 - Nov 1997
Volume 21, Issue 10 - Oct 1997
Volume 21, Issue 9 - Sep 1997
Volume 21, Issue 8 - Aug 1997
Volume 21, Issue 7 - Jul 1997
Volume 21, Issue 6 - Jun 1997
Volume 21, Issue 4 - Apr 1997
Volume 21, Issue 5 - Jan 1997
Volume 21, Issue 3 - Jan 1997
Volume 21, Issue 2 - Jan 1997
Volume 21, Issue 1 - Jan 1997
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Characteristics of bending strength and residual stress distribution on high thermal cycle of ceramic and metal joint
Park, Young-Chul ; Hue, Sun-Chul ; Boo, Myoung-Hwan ; Kim, Hyun-Su ; Kang, Jae-Wook ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1541~1550
DOI : 10.22634/KSME-A.19220.127.116.111
Since the ceramic/metal joint material is made at a high temperature, the residual stress develops when it is cooled from bonding temperature to room temperature due to remarkable difference of thermal expansion coefficient between ceramic and metal. As residual stress at ceramic/metal joints influences the strength of joints, it is important to estimate residual stress quantitatively. In this study, it is attempted to estimate joint residual stress of Si
STS304 joints quantitatively and to compare the strength of joints. The difference of residual stress is measured when repeated thermal cycl is loaded, under the conditions of the practical use of the ceramic/metal joint. The residual stress increases at 1 cycle of thermal load but decreases in 3 cycles to 10 cycles of thermal load. And 4-point bending test is performed to examine the influence of residual stress on fracture strength. As a result, it is known that the stress of joint decreases as the number of thermal cycle increases.
A study on the real time obstacle recognition by scanned line image
Cheung, Sheung-Youb ; Oh, Jun-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1551~1560
DOI : 10.22634/KSME-A.1918.104.22.1681
This study is devoted to the detection of the 3-dimensional point obstacles on the plane by using accumulated scan line images. The proposed accumulating only one scan line allow to process image at real time. And the change of motion of the feature in image is small because of the short time between image frames, so it does not take much time to track features. To obtain recursive optimal obstacles position and robot motion along to the motion of camera, Kalman filter algorithm is used. After using Kalman filter in case of the fixed environment, 3-dimensional obstacles point map is obtained. The position and motion of moving obstacles can also be obtained by pre-segmentation. Finally, to solve the stereo ambiguity problem from multiple matches, the camera motion is actively used to discard mis-matched features. To get relative distance of obstacles from camera, parallel stereo camera setup is used. In order to evaluate the proposed algorithm, experiments are carried out by a small test vehicle.
A study on the treatment of a max-value cost function in parametric optimization
Kim, Min-Soo ; Choi, Dong-Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1561~1570
DOI : 10.22634/KSME-A.1922.214.171.1241
This study explores the treatment of the max-value cost function over a parameter interval in parametric optimization. To avoid the computational burden of the transformation treatment using an artificial variable, a direct treatment of the original max-value cost function is proposed. It is theoretically shown that the transformation treatment results in demanding an additional equality constraint of dual variables as a part of the Kuhn-Tucker necessary conditions. Also, it is demonstrated that the usability and feasibility conditions on the search direction of the transformation treatment retard convergence rate. To investigate numerical performances of both treatments, typical optimization algorithms in ADS are employed to solve a min-max steady-state response optimization. All the algorithm tested reveal that the suggested direct treatment is more efficient and stable than the transformation treatment. Also, the better performing of the direct treatment over the transformation treatment is clearly shown by constrasting the convergence paths in the design space of the sample problem. Six min-max transient response optimization problems are also solved by using both treatments, and the comparisons of the results confirm that the performances of the direct treatment is better than those of the tranformation treatment.
Thermal Stress Analysis of Functuonally Graded Ceramic/Metal Composites(II)
Lim, Jae-Kyoo ; Song, Jun-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1571~1579
DOI : 10.22634/KSME-A.19126.96.36.1991
The development of a new material which should be continuously use under severe environment of very high temperature has been urgently requested. For the development of such super-heat resistant materials, the main problem is not only to make the superior thermal barrier properties but also to actively release thermal stress. So, a new concept of functionally graded material(FGM) has been proposed to overcome this problem. A composition and microstructure of FGM are varied continuously from place to place in ways designed to provide it with the maximum function of mitigating the induced thermal stress. So, FGM can be applied in the aerospace, the electronic and the medical field, etc.. In this study, thermal stress analysis of sintering PSZ/NiCrAlY graded material was conducted theoretically using a finite-element program. The temperature condition was sintering temperature assuming a cooling-down process up to room temperature. Fracture damage mechanism was anlayzed by the parameters of residual stress. It could be known that FGM provided with the function of mitigating the induced thermal stress.
Flapwise bending vibration analysis of rotating cantilever beams considering shear and rotary inertial effects
Shin, Sang-Ha ; Yoo, Hong-Hui ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1580~1588
DOI : 10.22634/KSME-A.19188.8.131.520
A modeling method for the flapwise bending vibration of a rotating cantilever beam which has small slenderness ratio is presented in this paper. It is shown that as the slenderness ratio decreases the shear and rotary inertia effects increase. Such effects become critical for the accurate estimation of the natural frequencies and modeshapes, especially higher frequencies and modes, as the angular speed increases. It is also shown that the flapwise bending natural frequencies are higher than the chordwise bending natural frequencies. The discrepancy between first natural frequencies are especially significant when the hub radius ratio is small.
Finite element analysis of eccentric loading in high-velocity impact forging
Yoo, Yo-Han ; Yang, Dong-Yol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1589~1597
DOI : 10.22634/KSME-A.19184.108.40.2069
The high-velocity impact forging process with eccentric loading condition is analyzed using the explicit time integration finite element method. In order to consider the strain hardening, strain rate hardening and thermal softening effects, which are frequently observed in high-velocity deformation phenomena, the Johnson-Cook constitutive model is applied to model the workpiece. It is assumed that the material response of the dies is elastic in the study. As a result of the eccentric loading simulation, it is found that the increase of the eccentric ratio and the allowable tilting angle cause the decrease of the maximum forging load and the blow efficiency, and it is also found that the forging load and the blow efficiency generated in the high-velocity impact forging process with three-dimensional geometry can be obtained efficiently.
A study on the improvement of the local stress field using the theory of conjugate approximations and loubignac's iterative method
Song, Kee-Nam ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1598~1608
DOI : 10.22634/KSME-A.19220.127.116.118
Based on the application of te theory of conjugate approximations and the Loubignac's iterative method in a local region, a method to improve the stress filed in a displacement-formulated finite element solution has been proposed. The validity of the proposed method has been tested through two examples : a thick cylinder under internal pressure loading and an infinite plate with a central circular hole subjected to uniaxial tension. As a result of analysis of the examples, it was found that the stress field obtained for the local region model by the proposed method approximates well for the whole domain model. In addition, it was found that because of a significant decrease in the computing time to obtain the improved stress field, the proposed method is efficient and useful for the detailed stress analysis in local regions.
Design of an Intelligent Polymer-Matrix-Composite Using Shape Memory Alloy
Jeong, Tae-Heon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1609~1618
DOI : 10.22634/KSME-A.1918.104.22.1689
Thermo-mechanical behaviors of polymer matrix composite(PMC) with continuous TiNi fiber are studied using theoretical analysis with 1-D analytical model and numerical analysis with 2-D multi-fiber finite element(FE) model. It is found that both compressive stress in matrix and tensile stress in TiNi fiber are the source of strengthening mechanisms and thermo-mechanical coupling. Thermal expansion of continuous TiNi fiber reinforced PMC has been compared with various mechanical behaviors as a function of fiber volume fraction, degree of pre-strain and modulus ratio between TiNi fiber and polymer matrix. Based on the concept of so-called shape memory composite(SMC) with a permanent shape memory effect, the critical modulus ratio is determined to obtain a smart composite with no or minimum thermal deformation. The critical modulus ratio should be a major factor for design and manufacturing of SMC.
Position servo control of a PR type pneumatic manipulator
Lim, Seung-Cheol ; Eao, Yun-Beom ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1619~1625
DOI : 10.22634/KSME-A.1922.214.171.1249
This paper concerns a 2-axis PR type pneumatic manipulator system translating in vertical and rotating in horizontal directions. A simplified linear model is mathematically formulated similar to the pneumatic acturators in dynamic responses in order to devise an appropriate position control scheme. A PD controller preceding the on/off solenoid valve turns out not only economical but also effective in reducing rise time and amplitude of limit cycles, if its control gains are determined on the basis of frequency response. And, additional implementation of symmetric or asymmetric deadband at the PD controller output greatly helps minimize valve opening numbers, positional error, and undesirable direction-dependent property due to the gravitational load. Such a control concept is synthesized through numerical simulations and next applied to the experimental set-up, featuring enhanced positional servo characteristics.
A study on the fatigue and fracture characteristics of localized nuclear reactor vessel material
Jeong, Sun-Eok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1626~1635
DOI : 10.22634/KSME-A.19126.96.36.1996
It is important to ensure the reliability of the first localized reactor vessel steel. To satisfy with this purpose, a study on the impact/hardness, low cycle fatigue(LCF), crack growth rate(da/dN) and fracture toughness( ) of base material(BM) and weld metal(WM) were performed under room temperature air and corrosion conditions. A summary of the results is as folows : (1) Charpy impact absorbed energy of BM was the highest value, heat affected zoon(HAZ) and the lowest, WM. The hardness of BM was similar to HAZ. (2) Coefficients of Manson equation using the monotonic tensile test data were obtained for the present material. (3) The effects of stress ratio and ambient (120.deg. C and NaCl) condition on da/dN were investigated, da/dN with NaCl condition expressed the highest value. (4) The results of Charpy V-notch impact test had good correlation with
characteristics and the lowest curve of
for BM was derived, more researches about WM and HAZ are required hereafter.
Dynamic characteristic identification of PWM solenoid valve for automatic transmission
Jung, Gyu-Hong ; Cho, Baek-Hyun ; Lee, Kyo-Il ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1636~1647
DOI : 10.22634/KSME-A.19188.8.131.526
As most of today's automatic transmissions in passenger car adopt a electro-hydraulic control system, the role of electronically controlled solenoid valves occupies an important position and it is essential to predict solenoid transient characteristics in order to design and evaluate the performance of the hydraulic control system. However, in general, both the magnetic and electrical parameters f the solenoid system are hardly known and it is not easy to model this section with moderate complexity although mechanical system could be developed using the classical second order system. This paper presents a dynamic modelling technique of a solenoid valve, that is controlled by pulse width modulation for an automatic transmission, in terms of system identification theory. In nonlinear computer simulation, it is shown that the identified systems which produce magnetic force to input duty cycle for various excitation signals predict the static and dynamic performance very well near the operating point and in experiment conducted to confirm the validity of identification theory for PWM solenoid valve, we find that there is a good agreement between the experimental data and simulation result. Hence, this model can be utilized in the development of pressure control system with PWM solenoid valve.
The Design Technique for Reducing the Intake Noise of Vehicle (Part I)
Oh, Jae-Eung ; Han, Kwang-Hee ; Lee, Kyu-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1648~1655
DOI : 10.22634/KSME-A.19184.108.40.2068
The intake noise, a major source of vehicle noises, has rapidly become a noticeable, and has been studied to reduce the level. Traditionally, the intake system has been developed through a experiment, namely, the trial and error process. This approach requires very high cost and long time consuming to develop the system. Recently, FEM and BEM are becoming useful in analysis of the intake system, and te results of analysis are very valid. But because these techniques also require high cost and long analysis time, these are generally not practical tool at the early stage of the development of an intake system. In this study, the software was developed to predict and analyze the acoustic characteristics of an intake system. It was based on the Transfer Matrix Method and operated to analyze a simplified intake system in a personal computer. It can be used early in the design stage of development of the intake system. This study presented an improvement to reduce the level of an intake noise. It was to select the optimum position of a resonator and verified by NIT/SYSNOISE, FE analysis commercial software, and testing a prototype.
The Design Technique for Reducing the Intake Noise of Vehicle (Part II)
Oh, Jae-Eung ; Han, Kwang-Hee ; Kim, Sang-Hun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1656~1665
DOI : 10.22634/KSME-A.19220.127.116.116
The intake noise, a major source of vehicle noises, has rapidly become a noticeable, and has been studied to reduce the level. Traditionally, the intake system has been developed through a experiment, namely, the trial and error process. This approach requires very high cost and long time consuming to develop the systm. Recently, FEM and BEM are becoming useful in analysis of the intake system, and the results of analysis are very valid. But because this techniques also require high cost and long analysis time, this technique is generally not practical tool at the early stage of the development. In this study, the software was developed to predict and analyze the acoustic characteristics of the intake system. It was based on the Transfer Matrix Method and operated to analyze a simplified intake system in a personal computer. It can be used early in the design stage of development of the intake system. This study presented a improvement to reduce the level of the intake noise, which modified the specification of the intake system. And the improvement were verified by NIT/SYSNOISE, FE analysis commercial software, and testing a prototype.
A free vibration analysis of sound-structure interaction plate having a small cut-out
Oh, Jae-Eung ; Rhee, Dong-Ick ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1666~1673
DOI : 10.22634/KSME-A.1918.104.22.1686
In order to investigate the characteristics of sound-structure interaction plate having a cut-out, we modeled a rectangular cavity and the flexible plate of the cavity. Because the particle velocity of air is the same as that of plate on the plate, we could easily redefine vibration equation using the velocity potential. We calculated the natural frequencies of plate using orthogonal polynomial functions which satisfy the boundary conditions in the Rayleigh-Ritz method. For the change of vibration characteristics, the effect of sound-structure interaction is more dominant than that of cut-out size.
Fatigue crack growth properties of ceramic coated 1Cr-1Mo-0.25V steel
Seo, Chang-Min ; Kim, Gyeong-Ryeol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1674~1682
DOI : 10.22634/KSME-A.1922.214.171.1244
Fatigue tests were performed to investigate the effect of ceramic coatings as in TiN and TiCN on fatigue crack growth properties of ceramic coated 1Cr-1Mo-0.25V steel with different coating thickness in laboratory air conditions. The experimental results are described with respect to a Paris equation, da/dN=C(.DELTA.K)
, where the crack growth rate of coated specimens provided as similar growth rate as that of the uncoated specimen regardless of coating thickness. Furthermore, it was observed that the type of coating layer had virtually no effect on crack growth rate in the full region of stress intensity factor range. And it was also appeared that the final crack length of TiCN coated specimens was short compared to that of TiN coated, and the substrate specimens, in which it was inferred due to lowering the toughness of coated material from high hardness of TiCN coating layer itself.
Position and load-swing control of a 2-dimensional overhead crane
Lee, Ho-Hoon ; Cho, Sung-Kun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1683~1693
DOI : 10.22634/KSME-A.19126.96.36.1993
In this paper, a new nonlinear dynamic model is derived for a 2-dimensional overhead crane based on a new definition of 2-degree-of-freedom swing angle, and a new anti-swing control law is proposed for the crane. The dynamic model and control law take simultaneous travel and traverse motions of the crane into consideration. The model is first linearized for small motions of the crane load about the vertical stable equilibrium. Then the model becomes decoupled and symmetric with respect to the travel and traverse axes of the crane. From this result, a decoupled anti-swing control law is proposed based on the linearized model via the loop shaping and root locus methods. This decoupled method guarantees not only fast damping of load-swing but also zero steady state position error with optimal transient response for the 2-dimensional motion of the crane. Finally, the proposed control method is evaluated by controlling the simultaneous travel and traverse motions of a 2-dimensional prototype overhead crane. The effectiveness of the proposed control method is then proven by the experimental results.
The behaviour of strength and fatigue crack propagation of various steels in steel bridges
Han, Seung-Ho ; Kim, Jung-Kyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1694~1701
DOI : 10.22634/KSME-A.19188.8.131.524
The residual safety assessment of steel structures, an important subject in practice, is given to much attention. Life prediction in the planning course of steel structures under fatigue loading is mainly based on fatigue design criteria resulting from S-N curves. But for any reason cracks have to be assumed due to fabrication failures or fatigue loading in service which can lead total fracture of structures. The life prediction can be carried out by means of fracture mechanics using Paris-Erdogan equation(
). The paper presents results from charpy test to interpret transition behaviour of charpy energy(
) in a wide temperature range and from constant-load-amplitude test to measure fatigue crack growth of various steels widely used in steel bridges since beginning of 20 centuries in Europe. In the normal service temperature range of steel bridges, the steel S355M shows higher maximum charpy energy(
) and lower transition temperature(
) than other steels considered. The C and m of Paris-Erdogan equation on the steels appear to be correlated, and to be affected by the R-ratios due to crack closure, especially at a low fatigue crack growth rate. Scanning electron microscopy analysis was carried out to interpret an influence of the crack closure effects on the correlation of C and m.
Effect of element size in hybrid stress analysis around a hole in loaded orthotropic composites
Baek, Tae-Hyun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1702~1711
DOI : 10.22634/KSME-A.19184.108.40.2062
A numerical study for the number of terms of a power series stress function and the effect of hybrid element size on stress analysis around a hole in loaded orthotropic composites is presented. The hybrid method coupling experimental and/or theoretical inputs and complex variable formulations involving conformal mappings and analytical continuity is used to calculate tangential stress on the boundary of the hole in uniaxially loaded, finite width glass epoxy tensile plate. The tests are done by rarying the number of terms, element size and nodal locations on the external boundary of the hybrid region. The numerical results indicate that the hybrid method is accurate and powerful in both experimental and numerical stress analysis.
Stability and accuracy for the trapezoidal rule of the Newmark time integration method with variable time step sizes
Noh, Yong-Su ; Chung, Jin-Tae ; Bae, Dae-Seong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1712~1717
DOI : 10.22634/KSME-A.19220.127.116.112
Stability and accuracy for the trapezoidal rule of the Newmark time integration method are analyzed when variable time step sizes are adopted. A new analytic approach to stability and accuracy analysis is also proposed for time integration methods with variable time step sizes. The trapezoidal rule with variable time step sizes has the "actual" unconditional stability which is the same as that of the method with constant time step sizes. However, the method with variable time step sizes is first-order accurate while the method with constant time step sizes is second-order accurate. accurate.
A study on motion errors due to acceleration and deceleration types of servo motors
Shin, Dong-Soo ; Chung, Sung-Chong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1718~1729
DOI : 10.22634/KSME-A.1918.104.22.1688
This paper describes motion errors due to acceleration and deceleration types of servo motors in NC machine tools. Motion errors are composed of two components : one is due to transient response of a servomechanism and the other comes from gain mismatching of positioning servo motors. It deals with circular interpolation to identify motion errors by using Interface card. Also in order to minimize motion errors, this study presents an effective method to optimize parameters which are connected with motion errors. The proposed method is based upon a second order polynomial regression model and it includes an orthogonal array method to make the effective results of experiments. The validity and reliability of the study were verified on a vertical machining center equipped with FANUC 0MC through a series of experiments and analysis.
Development of a profile measuring system for conductor roll
Choi, Yong-Jun ; Jun, Sung-Bai ; Lee, Eung-Suk ; Kim, Hyo-Sung ; Jang, Ji-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1730~1741
DOI : 10.22634/KSME-A.1922.214.171.1240
In this paper, we developed a surface profile measuring system and a profile measuring software for EGL conductor roll. For the profilemeter, we designed a linear guided control system with Laser displacement sensors and developed a 3-dimensional software. Additionally, the AC motor and AC motor driver were used to control the precise position of linear guide system. The measuring principle of the Laser sensor is optical triangulation method. Also, two Laser sensors were used to remove the disturbance and vibration effects of the linear guide system.
Acoustic characteristics of a loudspeaker obtained by vibration and acoustic analysis
Kim, Jung-Ho ; Kim, Jun-Tai ; Kim, Jin-Oh ; Min, Jin-Ki ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 10, 1997, Pages 1742~1756
DOI : 10.22634/KSME-A.19126.96.36.1992
The acoustic characteristics of a direct radiator type loudspeaker has been studied in this paper. The natural modes of the speaker cone vibration analyzed numerically by the finite element method have been verified by comparing them with experimental results. The so-ap-proved finite-element model has been used to calculate the vibration response of the cone excited by the voice coil. The vibration displacement of the speaker cone paper has been converted into the vibration velocity and used as a boundary condition for the acoustic analysis. The frequency characteristics, directivity, and sound pressure distribution of the loudspeaker have been calculated by the boundary element method. The numerical results have been verified by the experiments carried out in an anechoic chamber. The variations of the acoustic characteristics due to the changes of some design parameter values can be examined using the numerical model.