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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 40, Issue 9 - Sep 2016
Volume 40, Issue 8 - Aug 2016
Volume 40, Issue 7 - Jul 2016
Volume 40, Issue 6 - Jun 2016
Volume 40, Issue 5 - May 2016
Volume 40, Issue 4 - Apr 2016
Volume 40, Issue 3 - Mar 2016
Volume 40, Issue 2 - Feb 2016
Volume 40, Issue 1 - Jan 2016
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Control of Inertially Stabilized Platform Using Disturbance Torque Estimation and Compensation
Choi, Kyungjun ; Won, Mooncheol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 1, 2016, Pages 1~8
DOI : 10.3795/KSME-A.2016.40.1.001
In this study, we propose a control algorithm for Inertially Stabilized Platforms (ISP), which combines Disturbance Observer (DOB) with conventional proportional integral derivative (PID) control algorithm. A single axis ISP system was constructed using a direct drive motor. The joint friction was modeled as a nonlinear function of joint speed while the accuracy of the model was verified through experiments and simulation. In addition, various Q-filters, which have different orders and relative degrees of freedom (DOF), were implemented. The stability and performance of the ISP were compared through experimental study. The performance of the proposed PID-plus-DOB algorithm was compared with the experimental results of the conventional double loop PID control under artificial vehicle motion provided motion simulator with six DOF.
Experimental Study on Position Control System Using Encoderless Magnetic Motion
Kim, Hong-youn ; Yun, Young-Min ; Shim, Ho-Keun ; Kwon, Young-Mok ; Heo, Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 1, 2016, Pages 9~16
DOI : 10.3795/KSME-A.2016.40.1.009
A position control system composed of the PMLSM(Permanent Magnet Linear Synchronous Motor), unlike conventional linear permanent magnet synchronous motor is fixed to the permanent magnet moving coil rails (permanent magnet = stator, coil = mover), the coil is fixed, moving the permanent magnet, we propose a position control system (permanent magnet = mover, coil = stator) structure. Position is measured not using conventional encoder or resolver but by adopting vector control method using 2 hall sensors generating rectangular signal. This method estimate the velocity and position of mover by using the quadruple of two hall sensor signal instead of encoder signal. Vector control of PMLSM using 2 hall sensor generating rectangular wave is proved to control the system stable and efficiently through simulation. Also hardware experiment reveals that the position control performance is measured within the range of
in the accuracy of
, which is improved twice to the conventional method. The proposed method exhibits its economical efficiency and practical usefulness. The vector control technique using two hall sensors can be installed in narrow place, accordingly it can be implemented on the system where the conventional encoder or resolver cannot operate.
Design of Electromagnetic Moving-coil type Voice Coil Motor for Scanning mirror of Barcode reader
Shin, Bu Hyun ; Lee, Jeong Woo ; Shim, Hyun Ho ; Park, Sang Goo ; Lee, Seung-Yop ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 1, 2016, Pages 17~22
DOI : 10.3795/KSME-A.2016.40.1.017
A voice coil actuator with moving coil type for scanning mirror system of barcode reader has been developed. The actuator has a simple structure including a magnet, a coil and a pin. The performance of the actuator is analyzed by a linearized theoretical model. And the dynamic performance of the proposed actuator is predicted through motor constant and restoring constant obtained by finite element simulations. The theoretical model was verified by the prototype which has 64 Hz resonance frequency and 60 deg reflecting angle. We also discovered that that 3 V input can make the actuator rotate over 61.8 deg reflecting angle at 50 Hz resonance frequency. The proposed actuator can simplify its driving configuration because of its implementation of open-loop control.
High-Strain Rate Tensile Behavior of Pure Aluminum Single and Multi-Crystalline Materials with a Tensile Split Hopkinson Bar
Ha, Sangyul ; Jang, Jin Hee ; Yoon, Hyo Jun ; Kim, KiTae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 1, 2016, Pages 23~31
DOI : 10.3795/KSME-A.2016.40.1.023
In this study, we modified the conventional tensile split Hopkinson bar(TSHB) apparatus typically used for the high strength steel to evaluate the tensile deformation behavior of soft metallic sheet materials under high strain rates. Stress-strain curves of high purity single and multi-crystalline materials were obtained using this experimental procedure. Grain morphology and initial crystallographic orientation were characterized by EBSD(Electron Backscattered Diffraction) method measured in a FE-SEM(Field emission-scanning electron microscopy). The fractured surfaces were observed by using optical microscopy. The relationship between plastic deformation of aluminum crystalline materials under high-strain rates and the initial microstructure and the crystallographic orientations has been addressed.
Investigation of Hip Squeak Using Finite Element Modeling with a Friction Curve
Nam, Jaehyeon ; Park, Kiwan ; Kang, Jaeyoung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 1, 2016, Pages 33~39
DOI : 10.3795/KSME-A.2016.40.1.033
This study investigated the dynamic instability of a ceramic-on-ceramic artificial hip joint system through complex eigenvalue analysis. We examined the mode-coupling mechanism through eigenvalue sensitivity analysis with the variation of system parameters. In addition, we constructed a finite element model including the negative slope of friction curve for investigating the negative-slope mechanism in the hip squeak problem. The numerical results show that the torsion-dominant mode becomes unstable due to the presence of the negative slope while the axial load is the important factor influencing the negative-slope type instability.
Thermal Analysis of Ballscrew Systems by Explicit Finite Difference Method
Min, Bog-Ki ; Park, Chun-Hong ; Chung, Sung-Chong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 1, 2016, Pages 41~51
DOI : 10.3795/KSME-A.2016.40.1.041
Friction generated from balls and grooves incurs temperature rise in the ballscrew system. Thermal deformation due to the heat degrades positioning accuracy of the feed drive system. To compensate for the thermal error, accurate prediction of the temperature distribution is required first. In this paper, to predict the temperature distribution according to the rotational speed, solid and hollow cylinders are applied for analysis of the ballscrew shaft and nut, respectively. Boundary conditions such as the convective heat transfer coefficient, friction torque, and thermal contact conductance (TCC) between balls and grooves are formulated according to operating and fabrication conditions of the ballscrew. Explicit FDM (finite difference method) is studied for development of a temperature prediction simulator. Its effectiveness is verified through numerical analysis.
Structural Design and Evaluation of Six-component Wheel Dynamometer
Kim, Man Gee ; Joo, Jin Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 1, 2016, Pages 53~63
DOI : 10.3795/KSME-A.2016.40.1.053
Wheel dynamometers are used to measure dynamic load that is conveyed from the road to a vehicle while driving. In this paper, two types of six-component wheel dynamometers utilizing shear deformation and bending deformation were designed and evaluated. Prior to designing the shear and bending type wheel dynamometers, the shear and bending deformation behaviors of the basic structure of the wheel dynamometer itself were analyzed using finite element analysis. Strain analysis was performed repeatedly in order to obtain a similar output sensing strain for each load component. The design was modified with a bridge circuit in order to minimize coupling strain. The results indicated that the shear type dynamometer was expected to obtain stable characteristics due to uniform strain distribution while the bending type dynamometer was expected to obtain high-quality sensitivity performance due to consistent output sensitivity.
Finite Element Analysis of a Customized Eyeglass Frame Fabricated by 3D Printing
Lee, Ji-Eun ; Im, Young-Eun ; Park, Keun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 1, 2016, Pages 65~71
DOI : 10.3795/KSME-A.2016.40.1.065
In recent years, 3D printing has received increasing attention due to releases of low-cost 3D printers based on open-source platform. 3D printing is expected to reduce the barrier to entry in the traditional manufacturing processes by increasing flexibility and creating an advantage to manufacture customized products at low costs. In this study, a unique eyeglass frame was designed to have a snake shape, which has an asymmetric geometry unlike traditional frames. The eyeglass frame was designed in a customized manner by reflecting dimensional characteristics of a customer's face. Finite element analysis was performed to investigate the structural safety of the 3D printed frames during the assembly process. The analysis also considered the effect of anisotropic material properties as determined by tensile tests. The eyeglass frame was then printed using the customized sizes and the best building process. The eyeglass frame was successfully assembled with lenses and without structural failure during its assembly procedure.
Optimization of a Cam Profile in a Circuit Breaker to Improve Latching Performance
Lee, Jae Ju ; Jang, Jin Seok ; Park, Hyun Gyu ; Yoo, Wan Suk ; Kim, Hyun Woo ; Bae, Byung Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 1, 2016, Pages 73~79
DOI : 10.3795/KSME-A.2016.40.1.073
Higher circuit breaker safety standards can be obtained by increasing the sustaining time of the latching section. This time increase is achieved through velocity reduction after contacting when the closing mechanism operates. The potential for the re-closing phenomenon to occur is also reduced by obtaining time to return open latch. In this study, the sustaining time for the latching section was increased through cam profile optimization based on the displacement response of the moving parts. In addition, the existing performance velocity was also satisfied. A multibody dynamics model of the circuit breaker was developed using ADAMS. To validate the model, simulation results were compared to experiment results. Then, cam profile optimization was carried out using an optimal design program PIAnO. Design variables selected included the radial direction of the cam. Design sensitivity analysis was carried out by design section as well. As a result of optimization, the sustaining time for the latching section was increased.
New Seat Design and Finite Element Analysis for Anti-Leakage of Globe Valve
Lee, Sung Ho ; Kang, Gyeong Ah ; Kwak, Jae-Seob ; An, Ju Eun ; Jin, Dong Hyun ; Kim, Byung Tak ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 1, 2016, Pages 81~86
DOI : 10.3795/KSME-A.2016.40.1.081
The valves used to control or shut off the flow through a pipeline can be divided into many different types, including gate valves, globe valves, and check valves. Globe valves, in particular, have excellent properties, and because they can easily control the flow under high-pressure conditions, they are generally used in LNG ship and steam pipelines. In this paper, a method for changing the shape of a seat was suggested to solve the valve leakage problem from a structural perspective. In addition, the stress distribution and directional deformation were compared for each model. The suggested models were thus validated, and the optimized seat structure, which includes a self-supporting capability for decreasing the amount of leakage, was determined.
A Study on the Efficiency of a Load Sensing Main Control Valve Using SimulationX
Kim, Dong Myoung ; Lee, Jung Min ; Jung, Won Jee ; Jang, Joo Sup ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 1, 2016, Pages 87~95
DOI : 10.3795/KSME-A.2016.40.1.087
In this study, we develop a model of an open center and load-sensing system and for a main control valve to analyze system characteristics and efficiency using SimulationX. In order to analyze the operating characteristics of the pressure and flow of the main control valve of an open center system, a test was performed at each port. The reliability of the model was confirmed by comparing the similarity of the analysis results with the test results before analyzing the operating characteristics of the system. Development of the load sensing main control valve was performed by adding a flow sharing valve and a notched shape to the open center system based on it's the proven reliability. The authors performed the simulation under the same load conditions in order to compare the efficiency of the systems. Additionally, the combined operation performance was investigated by means of analyzing the characteristics of flow distribution under different load conditions.
Predictions of Unbalanced Response of Turbo Compressor Equipped with Active Magnetic Bearings through System Identification
Baek, Seongiki ; Noh, Myounggyu ; Lee, Kiwook ; Park, Young-Woo ; Lee, Nam Soo ; Jeong, Jinhee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 1, 2016, Pages 97~102
DOI : 10.3795/KSME-A.2016.40.1.097
Since vibrations in rotating machinery is a direct cause of performance degradation and failures, it is very important to predict the level of vibrations as well as have a method to lower the vibrations to an acceptable level. However, the changes in balancing during installation and the vibrational modes of the support structure are difficult to predict. This paper presents a method for predicting the unbalanced response of a turbo-compressor supported by active magnetic bearings (AMBs). Transfer functions of the rotor are obtained through system identification using AMBs. These transfer functions contain not only the dynamics of the rotor but also the vibrational modes of the support structure. Using these transfer functions, the unbalanced response is calculated and compared with the run-up data obtained from a compressor prototype. The predictions revealed the effects of the support structure, validating the efficacy of the method.
Adaptive Variable Weights Tuning in an Integrated Chassis Control for Lateral Stability Enhancement
Yim, Seongjin ; Kim, Wooil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 1, 2016, Pages 103~111
DOI : 10.3795/KSME-A.2016.40.1.103
This paper presents an adaptive variable weights tuning system for an integrated chassis control with electronic stability control (ESC) and active front steering (AFS) for lateral stability enhancement. After calculating the control yaw moment needed to stabilize a vehicle with a controller design method, it is distributed into the tire forces generated by ESC and AFS using weighted pseudo-inverse-based control allocation (WPCA). On a low friction road, lateral stability can deteriorate due to high vehicle speed. To cope with the problem, adaptive tuning rules on variable weights of the WPCA are proposed. To check the effectiveness of the proposed method, a simulation was performed on the vehicle simulation package, CarSim.
Virtual Brake Pressure Sensor Using Vehicle Yaw Rate Feedback
You, Seung-Han ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 1, 2016, Pages 113~120
DOI : 10.3795/KSME-A.2016.40.1.113
This paper presents observer-based virtual sensors for YMC(Yaw Moment Control) systems by differential braking. A high-fidelity empirical model of the hydraulic unit in YMC system was developed for a model-based observer design. Optimal, adaptive, and robust observers were then developed and their estimation accuracy and robustness against model uncertainty were investigated via HILS tests. The HILS results indicate that the proposed disturbance attenuation approach indeed exhibits more satisfactory pressure estimation performance than the other approach with admissible degradation against the predefined model disturbance.
Development of Furan Mold Design and Machining System for Marine Propeller Casting
Park, Jung Whan ; Jung, Chang Wook ; Kwon, Yong Seop ; Kang, Sung Pil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 1, 2016, Pages 121~128
DOI : 10.3795/KSME-A.2016.40.1.121
A furan mold design and machining system for marine propeller casting was developed. In general, a large marine propeller is produced by casting in a foundry, where the upper and lower molds are constructed of cement or other materials like furan. Then, the cast workpiece is machined and manually ground. Currently, furan mold construction requires a series of manual tasks. This introduces a fairly large amount of stock allowances, which require a considerable number of man-hours for later machining and grinding, and also increase the work processes. A mold design and off-line robot programming software tool with a six-axis robot hardware system was developed to enhance the shape accuracy and productivity. This system will be applied in a Korean ship building company.