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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Precision Engineering
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Journal DOI :
Korean Society of Precision Engineering
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Volume & Issues
Volume 30, Issue 12 - Dec 2013
Volume 30, Issue 11 - Nov 2013
Volume 30, Issue 10 - Oct 2013
Volume 30, Issue 9 - Sep 2013
Volume 30, Issue 8 - Aug 2013
Volume 30, Issue 7 - Jul 2013
Volume 30, Issue 6 - Jun 2013
Volume 30, Issue 5 - May 2013
Volume 30, Issue 4 - Apr 2013
Volume 30, Issue 3 - Mar 2013
Volume 30, Issue 2 - Feb 2013
Volume 30, Issue 1 - Jan 2013
Selecting the target year
Review of Technology Trends for Ceramics Removal-Machining
Kwak, Jae-Seob ; Kwak, Tae-Soo ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 12, 2013, Pages 1227~1235
DOI : 10.7736/KSPE.2013.30.12.1227
Ceramic materials are classified by oxide, nitride and carbide material and have high brittleness, strength and hardness. Ceramic materials are strong in compression but weak in shearing and tension. This review paper has focused on technology trends and mechanism analysis of ceramics removal machining. The ceramic materials have superior mechanical, physical and chemical properties, but it is very hard to machining and the use of ceramics has been limited because of high strength and brittleness. In this paper, technology trends of ceramic removal-machining was introduced for types of machining technology, abrasive machining, cutting process, laser machining and so on.
The Effect of Ultrasonic Vibration Table on ELID Grinding Process of Aluminum Nitride Ceramics
Kwak, Tea-Soo ; Jung, Myung-Won ; Kim, Geon-Hee ; Kwak, Ihn-Sil ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 12, 2013, Pages 1237~1243
DOI : 10.7736/KSPE.2013.30.12.1237
This study has focused on the effect of ultrasonic vibration table in ELID grinding process of aluminum nitride ceramics. Aluminum nitride ceramics has superior physical and chemical properties and widely used in IC, LSI substrate, package and so on. To achieve the high effective machining of brittle and high strength ceramics as like aluminum nitride, machining method combined ELID grinding and ultrasonic vibration has been adopted in this study. From the experimental results, material removal rate, MRR has been increased maximum 36 percent and spindle resistance has been decreased in using ultrasonic table. Surface roughness of ground surface became a little worse in using ultrasonic table but was somewhat improved in feed direction.
Development of ELID Monitoring System and its Application to ELID Grinding of Structural Ceramics
Kwak, Tae-Soo ; Kim, Gyung-Nyun ; Kwak, Ihn-Sil ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 12, 2013, Pages 1245~1251
DOI : 10.7736/KSPE.2013.30.12.1245
This study has focused on development of ELID monitoring system and its application to ELID grinding of structural ceramics. ELID monitoring system was consisted of grinding equipment, ELID power supply, grinding wheel, electrode and monitoring program. It can give a real time data to check spindle grinding resistance, wheel revolution, dressing current and voltage in ELID grinding process. The performance of developed system was evaluated by applying to grinding of structural ceramics, silicon carbide and alumina. As the results of experiments, monitored data for spindle resistance and ELID dressing current was useful to check steady-state ELID grinding process. From the comparison of spindle resistance between ELID grinding and conventional grinding process according to change of depth of cut, it could be confirmed that the spindle resistance in ELID grinding was lower than conventional grinding process.
Magnetic Abrasive Polishing Technology with Ceramic Particles
Kwak, Tae-Soo ; Kwak, Jae-Seob ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 12, 2013, Pages 1253~1258
DOI : 10.7736/KSPE.2013.30.12.1253
Ceramic particles as polishing abrasives are often used in a magnetic abrasive polishing process because they have strong wear resistance. Non-ferromagnetic ceramic abrasives should be mixed with ferromagnetic iron particles for controlling the mixture within a magnetic brush during the polishing process. This study describes the application of the ceramic particles for the magnetic abrasive polishing. The distribution of the magnetic abrasives attached on a tool varies with magnetic flux density and tool rotational speed. From the correlation between abrasive adhesion ratio in the tool and surface roughness produced on a workpiece, practical polishing conditions can be determined. A step-over for polishing a large sized workpiece is able to be selected by a S curve, and an ultrasonic vibration assisted MAP produces a better surface roughness and increases a polishing efficiency.
Application of Magnetic Assisted Polishing for ELID Ground Surface of Aluminum Oxide Ceramics
Lee, Yong-Chul ; Jung, Myung-Won ; Kim, Tae-Kyu ; Kwak, Tae-Soo ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 12, 2013, Pages 1259~1264
DOI : 10.7736/KSPE.2013.30.12.1259
This study has focused on the application of magnetic assisted polishing for ELID ground surface of aluminum oxide ceramics. Aluminum oxide ceramics has been widely used as advanced materials for electric, optic, mechanic, chemical usage and so on. In this study, ELID grinding and magnetic assisted polishing technology was adopted for high-effective manufacturing and high quality surface of ceramic parts. The characteristic of MAP machining have been evaluated by the value of surface roughness and surface profile before and after magnetic assisted polishing. As the results of experiments, the surface roughness after magnetic assisted polishing has shown a significant improvement and the surface roughness was more improved when the feed rate of tool became slow.
Modeling and Analysis of Thermal Effects of Underwater Laser Drilling for Ceramics
Kim, Teak Gu ; Kim, Joohan ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 12, 2013, Pages 1265~1271
DOI : 10.7736/KSPE.2013.30.12.1265
In this work, modeling and analysis of thermal effects laser drilling under water for ceramics were presented. Laser is a unique tool for machining ceramics due to the characteristic of non-contact material removal. However, ablation by a laser often induces a thermal effect on the material and an increased heat-affected-zone or deposition of debris can be observed on the machined parts. The underwater surrounding improved a heat transfer rate to cooling down the machined part and could prevent any deposition of debris near the machined surfaces and edges. The heat modeling was applied to obtain the temperature distributions as well as temperature gradients between the material and surroundings. The cooling effect of the underwater laser drilling was improved and a more stable temperature distribution was calculated. The actual laser drilling results of ceramic laser drilling were presented to verify the effects of underwater laser drilling.
Double-Pitch Dual Grating Method for Detecting the Axial Offset in Roll System
Kim, Geehong ; Ten, Aleksey-Desen ; Lim, Hyungjun ; Lee, Jaejong ; Choi, Keebong ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 12, 2013, Pages 1273~1279
DOI : 10.7736/KSPE.2013.30.12.1273
We propose a dual grating alignment technique for roll-to-roll positioning which allows achieving nanometer scale alignment by using micro-size marks. The high precision alignment system were designed and manufactured. It was confirmed that the optical system was properly adjusted and fully aligned with the dual gratings. The experiment and computer simulation results were presented. Alignment accuracy below 50 nm was achieved.
A Piezo-Driven Miniaturized XY Stage with Two Prismatic-Prismatic Joints Type Parallel Compliant Mechanism
Choi, Kee-Bong ; Lee, Jae Jong ; Kim, Gee Hong ; Lim, Hyung Jun ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 12, 2013, Pages 1281~1286
DOI : 10.7736/KSPE.2013.30.12.1281
In this paper, a miniaturized stage with two prismatic-prismatic joints (2-PP) type parallel compliant mechanism driven by piezo actuators is proposed. This stage consists of two layers which are a motion guide layer and an actuation layer. The motion guide layer has 2-PP type parallel compliant mechanism to guide two translational motions, whereas the actuation layer has two leverage type amplification mechanisms and two piezo actuators to generate forces. Since the volume of the stage is too small to mount displacement sensors, the piezo actuators embedding strain gauge sensors are chosen. With the strain gauge-embedded piezo actuators, a semi-control is implemented, which results in hysteresis compensation of the stage. As the results, the operating range of
, the resolution of 20 nm, and the bandwidth of 400 Hz in each axis were obtained in the experiments.
A Robust Pitch Control of Wind Turbine Systems
Han, Myung-Chul ; Sung, Chang-Min ; Hwang, Wook ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 12, 2013, Pages 1287~1293
DOI : 10.7736/KSPE.2013.30.12.1287
In this paper, we consider variable speed wind turbine systems containing uncertain elements. Though PI controller is generally used for pitch control, it cannot guarantee a stability and performance of the complicated wind turbine systems. A robust pitch control scheme is proposed to regulate the electric power output above the rated wind speed. The pitch controller is designed in order to guarantee uniform boundedness and uniform ultimate boundedness based on the bound values of the set where the uncertainties are laid or moves. In order to verify the proposed control scheme, we present stability analysis and simulation results using Matlab/Simulink.
The Improvement of Weldline and Flow mark Defection by using Injection Molding Analysis
Lee, Yeong Chang ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 12, 2013, Pages 1295~1301
DOI : 10.7736/KSPE.2013.30.12.1295
The cause of flow mark defect is known as non-uniform temperature of mold surface when the flow front meets the cold cavity. The exact definition and classification of Flow mark is not clear because the mechanism of flow mark is not figured out till now. Any injection molding analysis software can not predict the flow mark phenomena. To solve weldline and flow mark defects, the gate thickness is reduced to increase the melt front velocity and the melt front velocity of the flow mark area is increased from 82.3mm/s to 104.7mm/s. In addition, the bulk temperature of the flow mark area is increased from
by adding a cold slug well. The flow mark phenomena can be greatly reduced by increasing the flow front velocity and elevating the bulk temperature.
An Ultra-precision Lathe for Large-area Micro-structured Roll Molds
Oh, Jeong Seok ; Song, Chang Kyu ; Hwang, Jooho ; Shim, Jong Youp ; Park, Chun Hong ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 12, 2013, Pages 1303~1312
DOI : 10.7736/KSPE.2013.30.12.1303
We report an ultra-precision lathe designed to machine micron-scale features on a large-area roll mold. The lathe can machine rolls up to 600 mm in diameter and 2,500 mm in length. All axes use hydrostatic oil bearings to exploit the high-precision, stiffness, and damping characteristics. The headstock spindle and rotary tooling table are driven by frameless direct drive motors, while coreless linear motors are used for the two linear axes. Finite element method modeling reveals that the effects of structural deformation on the machining accuracy are less than
. The results of thermal testing show that the maximum temperature rise at the spindle outer surface is approximately
. Finally, performance evaluations of the error motion, micro-positioning capability, and fine-pitch machining demonstrate that the lathe is capable of producing optical-quality surfaces with micron-scale patterns with feature sizes as small as
on a large-area roll mold.
On Nanometer Positioning Control of Ultra-precision Hydrostatic Bearing Guided Feeding Table
Shim, Jongyoup ; Park, Chun-Hong ; Song, Chang-Kyu ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 12, 2013, Pages 1313~1320
DOI : 10.7736/KSPE.2013.30.12.1313
An ultraprecision multi-axis machine tool has been designed and developed in our laboratory. The machine tool has four moving axes which are composed of three linear axes and one rotational axis. It has a gantry type structure and the Z-axis is on the X-axis and the C-axis, on which a workpiece is located, is inside the Y-axis. This paper shows control performance improving method and procedure for the ultra-precision positioning control of a hydrostatic bearing guided linear axis. Through improvements of electrical and mechanical components for the control system such as control electronics and oil pumping systems, the control disturbing noise is decreased. Also by the frequency domain analysis of control system those problem-making system components are identified and modified with analytical methods. The controller is analyzed and designed from frequency domain data and system information. In the experimental control results the nanometer order control result is successfully presented.
Active Damping Control of an Air Bearing Stage with Magnetic Preloads
Ro, Seung-Kook ; Kim, Soohyun ; Kwak, Yoonkeun ; Park, Chun Hong ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 12, 2013, Pages 1321~1325
DOI : 10.7736/KSPE.2013.30.12.1321
In this paper, we proposed an air bearing stage with active magnetic preloads in vertical directions compensating motion errors and attenuating vibrations to improve dynamic characteristics. This preloaded design gives simpler configuration of the stage, and active control of preload can be used for compensating motion errors by feedforward method. To improve dynamic characteristics, vibration of the table is monitored by an accelerometer, and controlled by a DSP based digital controller with integrator and band pass filters for suppressing roll and pitch vibration modes. The modes were evaluated by measuring frequency response functions, and compared with compensated responses. This showed effective results for suppressing poorly damped regenerative vibration of air bearings.
Analysis on the Static Performance of Vacuum-Preloaded Porous Air Bearings
Khim, Gyungho ; Park, Chun Hong ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 12, 2013, Pages 1327~1333
DOI : 10.7736/KSPE.2013.30.12.1327
Air bearings are widely used in precision stages because of low friction and high motion accuracy, however, they suffer from low stiffness in comparison with rolling bearings or hydrostatic bearings. So, several preloading methods using weight, magnet and vacuum force, and opposing pads have been used to increase the stiffness of the air bearings. In this paper, pressure distributions of the vacuum preloaded porous air bearings are calculated using the proposed method. And then, the load capacity and stiffness are analyzed. For the vacuum preloaded air bearings, the stiffness is increased owing to reduced bearing clearance by vacuum force. The simulation results indicate that variation of vacuum pressure with clearance in the vacuum pocket gives rise to low stiffness, so the vacuum pocket should be designed for pressure to be constantly maintained regardless of the bearing clearance by means of large effective pumping speed.
The Behavioral Characteristics of a Droplet on the Line Patterned Surface Including Water Film
Lee, Changwoo ; Park, Jinyoung ; Cho, Handong ; Hwang, Woonbong ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 12, 2013, Pages 1335~1340
DOI : 10.7736/KSPE.2013.30.12.1335
Herein the water film was introduced to the hydrophilic area on the line patterned surface to solve the contradiction caused by surface roughness (high different wettability has advantage to control the droplet but high roughness for that high wettability difference causes obstruction of droplet moving). Thus the droplet on the water film could not be hindered to line direction but restricted to orthogonal direction, effectively. In addition, droplet behaviors according to droplet volume and line thickness were studied. Droplet fell off the line with narrowing the interface between the droplet and the water film on the line. When the droplet fell off the line, the plate angle was designated as a critical plate angle and it used as an indicator of surface capability to control the droplet. As a result critical plate angle increases as droplet volume decreases and line thickness increases.
A Study on the Dynamic Characteristics of TPMS Piezoelectric Element using Finite Element Method
Kim, Sung Jun ; Jung, Haeil ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 12, 2013, Pages 1341~1347
DOI : 10.7736/KSPE.2013.30.12.1341
Energy harvesting is a clean technology to obtain energy from the surrounding environment such as wind, sun, vibration and so on. In particular, the current TPMS (Tire Pressure Monitoring Device) is very small and attached to the outside of a vehicle and power supply of the TPMS is limited. Therefore, energy harvesting using vibration energy of piezoelectric materials is important to the TPMS. In this paper, we analyzed several models using ANSYS which is one of the FEA (Finite Element Analysis) package and compared corresponding strain frequency response functions of the TPMS. In addition, we confirmed that dynamic characteristics variations according to geometry changes have effects on the performance of the TPMS.