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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korean Society for Precision Engineering
Journal Basic Information
Journal DOI :
Korean Society of Precision Engineering
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Volume & Issues
Volume 6, Issue 4 - Dec 1989
Volume 6, Issue 3 - Sep 1989
Volume 6, Issue 2 - Jun 1989
Volume 6, Issue 1 - Mar 1989
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기계기술의 발전방향과 연구기관의 육성방안
Kim, Hun-Cheol ;
Journal of the Korean Society for Precision Engineering, volume 6, issue 2, 1989, Pages 22~29
A Study on Time-Varying Sliding Regime of VSC System
Kim, Joong-Wan ; Lee, Man-Hyung ;
Journal of the Korean Society for Precision Engineering, volume 6, issue 2, 1989, Pages 30~39
Variable structure control (VSC) systems control the state vectors using sliding regime (SR) constructed switching logic, switching plane and control law. Saturation function switching logic is used to improve the drawback which occurs in traditional sign function switching logic. Switching plane with time-varying parameter is proposed to improve the drawback which occurs in switching plane with constant parameter and it is suggested the control law which has time-varying parameter. The stability of VSC system controlled by proposed time-varying SR is discussed, and the good control behavior was shown through computer simulation using proposed SR.
A Study on the Machinability of Titanium
Cheong, Seong-Gyu ; Oh, Seok-Hyung ; Seo, Nam-Seob ;
Journal of the Korean Society for Precision Engineering, volume 6, issue 2, 1989, Pages 40~46
Recently, the researches on cutting the new material have been done for development of aerospace industrial engineering. Especially, titanium ally is well known as heat resisting, antiwear, anticorrosion and difficult-to-machine materials. Many studies on the analysis of shear angle have been done for improving productivity in cutting these materials. In case of titanium alloy, the saw-toothed type of chip which has wave surface of a triangular form, an eccentric from of a continuous type of chip that is produced in the cutting process, was checked. Nakayama supposed that a maximum shear strewss plane and the shear crack in the free surface made an angle of
.deg. , but it's usually much larger than that. In this paper, the author analyzed the shear conditions of the cutting process in the quick-stopping device with the help SEM-photographs, and measured the hypotenuse angle directly in the photographs of the chips. In conclusion, the author tried to find the shear angle in the cutting process with the saw-toothed chip and compared it with the shear angles which can be calculated from the theories established by others. The results obtained are as follows. 1. In case of the saw-toothed chips, the equivalent cutting ratio can be calculated by using the chip thickness to two-thirds of ramp height. 2. The theory of Ernst-Merchant is not applicable to the titanium and its alloys which does not fractured in accordance with the theory of maximum shear stress. 3. When we cut the titanium alloys which produced the saw-toothed chips, the shear angle can be found with the theories of Rowe-Spick, P.K. Wright and the measurement of hypotenuse angle.
A Study on the analogical analysis for the development and design of the electrical machine
Lee, Gwon-Hyeon ;
Journal of the Korean Society for Precision Engineering, volume 6, issue 2, 1989, Pages 47~57
This paper aims at describing a series development of the electrical machine, by using the Similarity Theory. The character of the electrical machine defined as the Four Terminal Network of the electrical and mechanical energy transmission system, and the analogy theory of the modelmachine can be developed by the Four Termianl System. Also the Restriction Parameter and Disturbance Parameter can be founded by the comparative data of the developed machine that is the character of the theory and measurement.
The Effects of Thickness on the Plastic Instability under Uniaxial Tension in Sheet Metal
Han, Gyu-Taek ; Gang, Dae-Min ; Gu, Yang ; Baek, Nam-Ju ;
Journal of the Korean Society for Precision Engineering, volume 6, issue 2, 1989, Pages 58~64
Plastic instability in uniaxial tension of commercial purity Al has been studied with the emphasis of effects of thickness in cold worked specimens and recrystallized specimens. The thickness change gave rise to change in stress state and the amount of strain localization in specimen after diffuse necking. Therefore the thickness of speci- men could control modes of plastic instability. Regardless of recrystallized or cold worked state, the necking mode changed from diffuse necking to local necking, at about 1.5 .approx. 2 mm in thickness.
A study on the development of Electro-hydraulic servo Excavator(1) -Simulation of the trajectory tracking control using VSS-
Heo, Jun-Yeong ; Ha, Seok-Hong ; Lee, Jin-Geol ;
Journal of the Korean Society for Precision Engineering, volume 6, issue 2, 1989, Pages 65~76
The objective of this paper is to design the variable structure system(VSS) controller for the tracking control of excavator which is driven by electro-hydraulic servomechansim. It is generally agreed that the dynamic characteristics of the robot arm such as excavator are coupled, time varying, and highly nonlinear, and also hydraulic system contains nonlinear characteristics in itself, so performing exact position control and trajectory tracking control need remarkable consideration. To solve this porblem, this system was designed as a variable structure system. The salient feature of VSS is that the sliding mode occur on a switching surface. While in sliding mode, the system remains insensitive to parameter variations and disturbances. This control algorithm was applied to a hydraulic excavator by simulaltion and to a simulator by experiment. And its effectiveness was verified. And the results of VSS for the electro-hydraulic excavator was compared with that of the PID when load disturbances and system parameter variations exist.
A Study on the Chatter Analysis & Dynamic Stability of Drilling Mchine
Park, Jong-Kweon ; Lee, Hu-Sang ;
Journal of the Korean Society for Precision Engineering, volume 6, issue 2, 1989, Pages 77~87
This study is carried out to estimate the influence of cutting speed on the dynamic stability of a drilling machine. The theoretical stabilityu chart is constructed by using the measurd dynamic characteristics of the drilling machine. The critical cutting width and speed predicted from the stability chart show excellent agreements with those measured. Therefore it is confirmed that the analysis technique used in this study is useful for the prediction of the dynamic instability and improvement of the dynamic characteristics of drilling machines.
A Design of Robust Controller for the Turret Servo System Using LQG/LTR Method
Kim, Jong-Hwa ; Hur, Nam-Soo ; Lee, Man-Hyung ;
Journal of the Korean Society for Precision Engineering, volume 6, issue 2, 1989, Pages 88~97
In general turret servo system is subject to influnces by disturbances and uncertain modeling errors, which result from large dynamic characteristics and high-spedd operation. In this paper the influences of such disturbances and modeling errors are analyzed quali- tatively for the linerar approximation model of turret servo system, and then LQG/LTR control theory is applied to linear approximation model in order to design a controller which satisfies robustness/stability for the modeling errors. Finally the performance and robustness of designed controller for the given plant are verified through the simulation.