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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
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Volume & Issues
Volume 28, Issue 12 - Dec 2004
Volume 28, Issue 11 - Nov 2004
Volume 28, Issue 10 - Oct 2004
Volume 28, Issue 9 - Sep 2004
Volume 28, Issue 8 - Aug 2004
Volume 28, Issue 7 - Jul 2004
Volume 28, Issue 6 - Jun 2004
Volume 28, Issue 5 - May 2004
Volume 28, Issue 4 - Apr 2004
Volume 28, Issue 3 - Mar 2004
Volume 28, Issue 2 - Feb 2004
Volume 28, Issue 1 - Jan 2004
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High-resolution Capacitive Microaccelerometers using Branched finger Electrodes with High-Amplitude Sense Voltage
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 1, 2004, Pages 1~10
DOI : 10.3795/KSME-A.2004.28.1.001
This paper presents a navigation garde capacitive microaccelerometer, whose low-noise high-resolution detection capability is achieved by a new electrode design based on a high-amplitude anti-phase sense voltage. We reduce the mechanical noise of the microaccelerometer to the level of 5.5
/(equation omitted) by increasing the proof-mass based on deep RIE process of an SOI wafer. We reduce the electrical noise as low as 0.6
/(equation omitted) by using an anti-phase high-amplitude square-wave sense voltage of 19V. The nonlinearity problem caused by the high-amplitude sense voltage is solved by a new electrode design of branched finger type. Combined use of the branched finger electrode and high-amplitude sense voltage generates self force-balancing effects, resulting in an 140％ increase of the bandwidth from 726㎐ to 1,734㎐. For a fixed sense voltage of 10V, the total noise is measured as 2.6
/(equation omitted) at the air pressure of 3.9torr, which is the 51％ of the total noise of 5.1
/(equation omitted) at the atmospheric pressure. From the excitation test using 1g, 10㎐ sinusoidal acceleration, the signal-to-noise ratio of the fabricated microaccelerometer is measured as 105㏈, which is equivalent to the noise level of 5.7
/(equation omitted). The sensitivity and linearity of the branched finger capacitive microaccelerometer are measured as 0.638V/g and 0.044％, respectively.
Boundary Control of an Axially Moving Nonlinear Tensioned Elastic String
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 1, 2004, Pages 11~21
DOI : 10.3795/KSME-A.2004.28.1.011
In this paper, an active vibration control of a tensioned elastic axially moving string is investigated. The dynamics of the translating string ale described by a non-linear partial differential equation coupled with an ordinary differential equation. The time varying control in the form of the right boundary transverse motions is suggested to stabilize the transverse vibration of the translating continuum. A control law based on Lyapunov`s second method is derived. Exponential stability of the translating string under boundary control is verified. The effectiveness of the proposed controller is shown through the simulations.
Optimum Design of a Micro-fluidic Oscillator
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 1, 2004, Pages 22~30
DOI : 10.3795/KSME-A.2004.28.1.022
A micro-fluidic oscillator is used to control a linear actuator in a dynamic microsystem. The pressure difference at its two output ports causes the linear actuator to move, and it is a standard of judging the performance of the oscillator. The performance can be improved by optimizing the geometry of the oscillator, which has to enable fluid jet to switch at low inlet velocity. For this, in this study the relationship between the pressure coefficient (difference) and geometric parameters is obtained through the analysis using the software FLUENT. From the results the optimized model that maximize the output pressure difference is obtained by using a cyclic coordinate method that is one of optimization methods. As a result not only the performance is improved, but also the working range is more widen.
Study on the Design of Cam-type Transfer Unit
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 1, 2004, Pages 31~39
DOI : 10.3795/KSME-A.2004.28.1.031
This paper presents design solutions for cam type transfer unit in which feeding, lifting, and clamping motions are generated by cams. In order to achieve faster transfer motion, each designed cam must satisfy the given specifications such as velocity, acceleration, jerk, pressure angle, cam thickness, and torque. To reduce absolute torque magnitude and torque variation, a conjugate cam and a torque reduction cam are used respectively. The conjugate cam eliminates the redundant pre-load by using complementary cam to avoid jumping between a cam and a follower. The torque reduction cam reduces the torque variation by applying opposite torque to a cam shaft. The experimental result shows the reductions of the absolute torque value and torque variation. The improvement of working speed and life span of cam type transfer unit can be expected.
3-Axis Coupling Controller for High-Precision/High-Speed Contour Machining
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 1, 2004, Pages 40~47
DOI : 10.3795/KSME-A.2004.28.1.040
This paper proposes a three-axis coupling controller designed to improve the contouring accuracy in machining of 3D nonlinear contours. The proposed coupling controller is based on an innovative 3D contour error model and a PID control law. The novel contour error model provides almost exact calculation of contour errors in real-time for arbitrary contours and can be integrated with any type of existing interpolator. In the proposed method, three axes of motion are coordinated by the proposed coupling controller along with a proportional controller for each axis. The proposed contour error model and coupling controller are evaluated through computer simulations. The simulation results show that the proposed 3-axis coupling controller with the new contour error model substantially can improve the contouring accuracy by order of magnitude compared with the existing uncoupled controllers in high-speed machining of nonlinear contours.
Optimization of Flexible Multibody Dynamic Systems Using Equivalent Static Load Method
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 1, 2004, Pages 48~54
DOI : 10.3795/KSME-A.2004.28.1.048
Generally, structural optimization is carried out based on external static loads. All forces have dynamic characteristics in the real world. Mathematical optimization with dynamic loads is extremely difficult in a large-scale problem due to the behaviors in the time domain. In practical applications, it is customary to transform the dynamic loads into static loads by dynamic factors, design codes, and etc. But the optimization results with the unreasonably transformed loads cannot give us good solutions. Recently, a systematic transformation has been proposed as an engineering algorithm. Equivalent static loads are made to generate the same displacement field as the one from dynamic loads at each time step of dynamic analysis. Thus, many load cases are used as the multiple loading conditions which are not costly to include in modem structural optimization. In this research, the proposed algorithm is applied to the optimization of flexible multibody dynamic systems. The equivalent static load is derived from the equations of motion of a flexible multibody dynamic system. A few examples that have been solved before are solved to be compared with the results from the proposed algorithm.
Evaluation of Delamination Behavior in Hybrid Composite Using the Crack Length and the Delamination Width
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 1, 2004, Pages 55~62
DOI : 10.3795/KSME-A.2004.28.1.055
Although the previous researches evaluated the fatigue behavior of glass fiber/epoxy laminates using the traditional fracture mechanism, their researches were not sufficient to do it: the damage zone of glass fiber/epoxy laminates was occurred at the delamination zone instead of the crack-metallic damages. Thus, previous researches were not applicable to the fatigue behavior of glass fiber/epoxy laminates. The major purpose of this study was to evaluate delamination behavior using the relationship between crack length and delamination width in hybrid composite material such as Al/GFRP laminate. The details of investigation were as follows : 1) Relationship between crack length and delamination width, 2) Relationship between delamination aspect ratio and delamination area rate, 3) Variation of delamination growth rate is attendant on delamination shape factors. The test results indicated that the delamination growth rate depends on delamination width delamination aspect ratio and delamination shape factors.
Development of a Barrier Embedded Chaotic Micromixer
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 1, 2004, Pages 63~69
DOI : 10.3795/KSME-A.2004.28.1.063
It is of great interest to enhance mixing performance in a microchannel in which the flow is usually characterized as a low Reynolds number (Re) so that good mixing is quite difficult to be achieved in this laminar flow regime. In this regard, we present a new chaotic passive micromixer, named Barrier Embedded Micromixer (BEM), of which the mixing mechanism is based on chaotic flows. In BEM, chaotic flow is induced by periodic perturbation of the velocity field due to periodically inserted barriers along the channel wall while a helical type of flow is obtained by slanted grooves on the bottom surface of the channel in the pressure driven flow. To experimentally compare the mixing performance, a T-microchannel and a microchannel with only slanted grooves were also fabricated. All microchannels were made of PDMS (Polydimethylsiloxane) from SU-8 masters that were fabricated by conventional photolithography. Mixing performance was experimentally characterized with respect to an average mixing intensity by means of color change of phenolphthalein as pH indicator. It was found that mixing efficiency decreases as Re increases for all three micromixers. Experimental results obviously indicate that BEM has better mixing performance than the other two. Chaotic mixing mechanism, suggested in this study, can be easily applied to integrated microfluidic systems , such as Micro-Total-Analysis-System, Lab-on-a-chip and so on.
Chatter Detection for Improving Surface Quality of Hard Turning Process with Wavelet Transformation
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 1, 2004, Pages 70~78
DOI : 10.3795/KSME-A.2004.28.1.070
This paper presents study of efficiency of wavelet transformation for on-line chatter detection during hard fuming process. From comparison with other time series and statistical methods such as fast fourier transformation (FFT), Kurtosis and standard deviation (STD), wavelet transform is better than others in on-line chatter detection. With using wavelet function with pseudo frequency corresponding to chatter frequency, chatter could be detected more sensitively. And for both force signal from dynamometer and displacement signal from capacitance type cylindrical sensor (CCS), wavelet transform with DB2 function on level 4 could be well used for chatter detection in hard turning process.
An Experimental Study of the Effect of Process Conditions on Direct Surface Forming of a Light-Guide
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 1, 2004, Pages 79~84
DOI : 10.3795/KSME-A.2004.28.1.079
A light-guide is one of several important components of backlight unit in TFT-LCD. The manufacturing technology and optical system design of the light guide is very sensitive to quality and cost of the TFT-LCD module. In the present study a new manufacturing method which is called as direct surface forming(DSF) has been tested under various conditions. DSF is very similar to the well-known hot embossing except for partial contact between mold and substrate. The final V-groove pattern shows different shapes depend on the temperature of mold surface, contact time of mold and depth of V-groove.
Chemo-Mechanical Polishing Process of Sapphire Wafers for GaN Semiconductor Thin Film Growth
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 1, 2004, Pages 85~91
DOI : 10.3795/KSME-A.2004.28.1.085
The sapphire wafers for blue light emitting devices were manufactured by the implementation of the surface machining technology based on micro-tribology. This process has been performed by chemical and mechanical polishing process. The sapphire crystalline wafers were characterized by double crystal X-ray diffraction. The sample quality of sapphire crystalline wafer at surfaces has a full width at half maximum of 89 arcsec. The surfaces of sapphire wafer were mechanically affected by residual stress during the polishing process. The wave pattern of optical interference of sapphire wafer implies higher abrasion rate in the edge of the wafer than its center from the Newton`s ring.
Development Strategy for Customized Flexible CAD Systems Using Application Programming Interface
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 1, 2004, Pages 92~99
DOI : 10.3795/KSME-A.2004.28.1.092
With the advent of computers, CAD systems are widely used for various design practice. Complexity of CAD systems and difficulty of exchanging data among different CAD systems, however, do not allow efficient use as desired. In addition, to follow variety of designers` need, CAD activities should be customized. This article proposed a methodology fer developing an intelligent CAD system and the sate-of-the-art technologies described fur customizing CAD systems using API (Application Programming Interface). A basic platform is proposed and a useful application system is implemented to enable a parametric design by directly inputting numerical values on a CAD model. Based on this application, we developed a system that makes it possible to share part family data between SolidEdge and Pro/Engineer. The proposed concept on intelligent CAD systems facilitates integration of external systems such as CAE tools and promotes the use of CAD for both engineering designers and analysts.
The Singularity Analysis of the Casing Oscillator
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 1, 2004, Pages 100~108
DOI : 10.3795/KSME-A.2004.28.1.100
In this paper, the new casing oscillator, which is a construction machine and which structure is similar to that of a parallel manipulator with redundancy, is proposed. The singularity analysis of this machine is performed by two different methods. First, the singularities are found by the numerical method at configurations where the rank of the Jacobian matrix becomes deficient. The singularities are outside the workspace. To investigate the physical information on these configurations, the singularities are examined by the geometric method at configurations where the casing oscillator cannot resist the external forces and moments applied to the upper platform due to losing static equilibrium. The results of the geometric method are the same as those of the numerical method. It proves that the new casing oscillator is free from the singularity, which causes serious problems to a parallel manipulator.