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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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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 29, Issue 12 - Dec 2012
Volume 29, Issue 11 - Nov 2012
Volume 29, Issue 10 - Oct 2012
Volume 29, Issue 9 - Sep 2012
Volume 29, Issue 8 - Aug 2012
Volume 29, Issue 7 - Jul 2012
Volume 29, Issue 6 - Jun 2012
Volume 29, Issue 5 - May 2012
Volume 29, Issue 4 - Apr 2012
Volume 29, Issue 3 - Mar 2012
Volume 29, Issue 2 - Feb 2012
Volume 29, Issue 1 - Jan 2012
Selecting the target year
Properties of ELID Mirror-Surface Grinding for Single Crystal Sapphire Optics
Kwak, Jae-Seob ; Kim, Geon-Hee ; Lee, Yong-Chul ; Ohmori, Hitoshi ; Kwak, Tae-Soo ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 3, 2012, Pages 247~252
DOI : 10.7736/KSPE.2012.29.3.247
This study has been focused on application of ELID mirror-surface grinding technology for manufacturing single crystal optic sapphire. Single crystal sapphire is a superior material with optic properties of high performance as light transmission, thermal conductivity, hardness and so on. Mirror-surface machining technology is necessary to use sapphire as optic parts. The ELID grinding system has been set up for machining of the sapphire material. According to the ELID experimental results, it shows that the surface of sapphire can be eliminated by metal bonded wheel with micron abrasives and the surface roughness of 60nmRa can be gotten using grinding wheel of 2,000 mesh in 4.5um, depth of cut. In this study, the chemical experiments after ELID grinding also has been conducted to check chemical reaction between workpiece and grinding wheel on ELID grinding process. It shows that the chemical reaction has not happened as the results of the chemical experiments.
The Characteristics on Ultra Precision Machining for Infrared Optical Materials
Yang, Sun-Choel ; Huh, Myung-Sang ; Kim, Sang-Hyuk ; Lee, Gil-Jae ; Lee, Sang-Yong ; Kook, Myung-Ho ; Chang, Ki-Soo ; Ryu, Seon-Young ; Won, Jong-Ho ; Kim, Geon-Hee ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 3, 2012, Pages 253~260
DOI : 10.7736/KSPE.2012.29.3.253
In nowadays, the infrared optics is frequently employed to various fields such as military, aerospace, industry and medical. To develop the infrared optics, special glasses which can transmit infrared wave are required. Ge(Germanium), Si(silicon), and fluoride glasses are typically used for material of the infrared optics. Compared with Ge and Si glasses, fluoride glasses have high transmittance in infrared wavelength range. Additionally, UV(ultraviolet) and visible light can be transmitted through fluoride glasses. There characteristics of fluoride glasses makes it possible to evaluate optical performance with generally used visible testing equipment. In this paper, we used design of experiment to find ultra precision machining characteristic of Ge and fluoride glasses and optimized machining process to obtain required form accuracy of PV(Peak to Valley)
Ultraprecision Grinding of Glassy Carbon Core for Mold Press Lens
Hwang, Yeon ; Cha, Du-Hwan ; Kim, Jeong-Ho ; Kim, Hye-Jeong ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 3, 2012, Pages 261~265
DOI : 10.7736/KSPE.2012.29.3.261
In this study, glassy carbon was ground for lens core of glass mold press. Ultraprecision grinding process was applied for machining of core surfaces. During the process, brittle crack occurred because of hard-brittleness of glassy carbon. Author investigated optimized grinding conditions from the viewpoint of ductile mode grinding. Geometrical undeformed chip thickness was adopted for critical chip thickness that enables crack free surface. Machined cores are utilized for biaspheric glass lens fabrication and surfaces of lens were compared for verification of ground surface.
Magnetic Abrasive Polishing and Its Application
Kwak, Tae-Soo ; Kwak, Jae-Seob ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 3, 2012, Pages 266~272
DOI : 10.7736/KSPE.2012.29.3.266
This paper has aims to share fundamental knowledge for magnetic abrasive polishing and to mainly introduce recent research results. In order to enhance a magnetic flux density for nonferrous materials, advanced magnetic abrasive polishing system which is called 2nd generation system was established by electro-magnet array table, and the effectiveness of the electromagnet array table was evaluated in real polishing experiments. To increase adhesiveness of the abrasives in high speed polishing, a silicone gel agent was proposed and carbon nanotube particles as new magnetic abrasives were applied in the magnetic abrasive polishing. In addition, a strategy for optimal step-over determination by heuristic algorithm was introduced for applying large size workpiece. Curved surfaces having a uniform radius were simulated and tested with installed electro-magnet array table.
Densification and Properties of ZrB
-based Ceramics for Ultra-high Temperature Applications
Kim, Seong-Won ; Kim, Hyung-Tae ; Kim, Kyung-Ja ; Seo, Won-Seon ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 3, 2012, Pages 273~278
DOI : 10.7736/KSPE.2012.29.3.273
has a melting temperature of
and a low density of
, which makes this a candidate for application to ultra-high temperature over
. Beside these properties,
has excellent resistance to thermal shock and oxidation compared with other non-oxide engineering ceramics. This paper reviewed briefly 2 research examples, which are related to densification and properties of
-based ceramics for ultra-high temperature applications. In the first section, the effect of
addition on the densification and properties of
-based ceramics is shown.
-20 vol.% SiC system was selected as a basic composition and
or C was added to this system in some extents. With sintered bodies, densification behavior and hightemperature (up to
) properties such as bending strength and hardness are examined. In the second section, the effect of the SiC size on the microstructures and physical properties is shown.
-SiC ceramics are fabricated by using various SiC sources in order to investigate the grain-growth inhibition and the mechanical/thermal properties of
Physically Compatible Characteristic Length of Cutting Edge Geometry
Ahn, Il-Hyuk ; Kim, Ik-Hyun ; Hwang, Ji-Hong ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 3, 2012, Pages 279~288
DOI : 10.7736/KSPE.2012.29.3.279
The material removal mechanism in machining is significantly affected by the cutting edge geometry. Its effect becomes even more substantial when the depth of cut is relatively small as compared to the characteristic length which represents the shape and size of the cutting edge. Conventionally, radius or focal length has been employed as the characteristic length with the assumption that the shape of cutting edge is round or parabolic. However, in reality, there could be various ways to determine the radius or focal length even for the same tool edge profile, depending on the region to be considered as cutting edge in the measured profile and the constraints to be set in constructing the best fitted circle or parabola. In this regard, the present study proposes various models to determine the characteristic length in terms of radius or focal length. Their physical compatibility are validated by carrying out 2D orthogonal cutting experiments using inserts with a wide range of characteristic length (
in terms of radius) and then by investigating the correlation between the characteristic length and the cutting forces. Such validation is based on the common belief that the larger the characteristic length is, the blunter the cutting edge is and the higher the cutting forces are. Interestingly, the results showed that the correlation is higher for the radius or focal length obtained with a constraint that the center of best fitted circle or the focus of the best fitted parabola should be on the bisectional line of the wedge angle of tool.
Wafer Edge Profile Control for Improvement of Removal Uniformity in Oxide CMP
Choi, Sung-Ha ; Jeong, Ho-Bin ; Park, Young-Bong ; Lee, Ho-Jun ; Kim, Hyoung-Jae ; Jeong, Hae-Do ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 3, 2012, Pages 289~294
DOI : 10.7736/KSPE.2012.29.3.289
There are several indicators to represent characteristics of chemical mechanical planarization (CMP) such as material removal rate (MRR), surface quality and removal uniformity on a wafer surface. Especially, the removal uniformity on the wafer edge is one of the most important issues since it gives a significant impact on the yield of chip production on a wafer. Non-uniform removal rate at the wafer edge (edge effect) is mainly induced by a non-uniform pressure from nonuniform pad curvature during CMP process, resulting in edge exclusion which means the region that cannot be made to a chip. For this reason, authors tried to minimize the edge exclusion by using an edge profile control (EPC) ring. The EPC ring is equipped on the polishing head with the wafer to protect a wafer from the edge effect. Experimental results showed that the EPC ring could dramatically minimize the edge exclusion of the wafer. This study shows a possibility to improve the yield of chip production without special design changes of the CMP equipment.
Visualization of Electro-hydrodynamic Ink Jetting using CCD Camera
Kwon, Kye-Si ; Lee, Dae-Yong ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 3, 2012, Pages 295~301
DOI : 10.7736/KSPE.2012.29.3.295
The method for spraying of liquids through an electrical field has become a printing method since it can make very small droplet. For electro-hydrodynamic jet printing to become a reliable jetting tool, the jetting performance should be characterized with respect to various jetting conditions. To optimize jetting conditions, the jetting behavior should be measured. In this study, we present a visualization techniques to measure jetting behavior from electro-hydrodynamic (EHD) inkjet head. Unlike most previous method, we use the CCD camera to measure the jetting behavior. For this purpose, LED light is synchronized with jetting signal and sequential image was obtained by adjusting the delay time of the LED light. Finally, merits and demerits of using CCD camera were discussed to measure jetting image from EHD inkjet head.
Development and Evaluation of the Biomimetic Actuator based on Bacterial Cellulose
Kim, Si-Seup ; Kee, Chang-Doo ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 3, 2012, Pages 302~306
DOI : 10.7736/KSPE.2012.29.3.302
Bacterial cellulose based actuator with large displacement was developed for biomimetic robots. Bacterial cellulose has 3D nanostructure with high porosity which was composed of the nanofibers. Freeze dried bacterial cellulose was dipped into ionic liquid solution such as 1-butyl-3-methylimidazolium(BMIMCl) to enhance the actuation performance due to increase the ionexchange capacity and ionic conductivity. And Poly(3,4-ethylenedioxythiophene)-poly (styrnenesulfonate)(PEDOT:PSS) was used for the electrodes of both side of bacterial cellulose actuator by dipping and drying method. The FT-IR and XRD were conducted to examine the electrochemical changes of developed bacterial cellulose actuator. The biomimetic caudal fin was designed using bacterial cellulose actuator and PDMS to verify the possibility for biomimetic robot. The step and harmonic response were conducted to evaluate the performance of developed biomimetic actuator.
Role of Post Weld Treatment Methods in the Improvement of Fatigue Life for T-type Welded Structures Made by SM 50A Steel
Han, Chang-Wan ; Lee, Jae-Hoon ; Song, Jun-Hyouk ; Lee, Hyun-Woo ; Park, Seong-Hun ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 3, 2012, Pages 307~312
DOI : 10.7736/KSPE.2012.29.3.307
This study aims to investigate the effect of the post weld treatments on the fatigue life of T-type welded structure made by a SM50A steel material, generally used for excavators, because changes in the geometry, material and surface properties of welded regions affect the fatigue life of welded structures. T-type test specimens were prepared by the CO2 welding of rolled steel plates (SM50A steel) with a thickness of 10 mm at a welding speed of 30 cm/min and these Ttype welded specimens were further treated by UIT (Ultrasonic Impact Treatment) and/or toegrinding post welding treatment methods. In order to investigate improvements on the fatigue life of the samples. 3-point bending fatigue tests were conducted with a stress ratio of R=0.1 under a cyclic loading environment at a frequency of 5 Hz, via a hydraulic fatigue testing machine (
, MTS 809). The tests were performed at room temperature. The fatigue life of UIT specimens was approximately 25 times longer than that of as-welded specimens at a stress amplitude of 281 MPa, while toe-grinding specimens exhibited 4.15 times longer fatigue life. The current results could provide important guidelines to determine the proper post weld treatment methodologies of T-type welded parts for excavators with a satisfactory fatigue life although under severe operating conditions.
An Experimental Study on the Mechanical Properties of T-Joints Structure using CFRP/Al Honeycomb Sandwich Composite
Cho, Ki-Dae ; Ha, Sung-Rok ; Kang, Kwang-Hee ; Kim, Jie-Eok ; Yang, Sung-Chul ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 3, 2012, Pages 313~318
DOI : 10.7736/KSPE.2012.29.3.313
Application of composite structures on naval ships strongly depends on the mechanical strength and collapse behavior of the T-joints of the whole structure. Because of the weight advantages over single skin composite and bolt fastening joining, three types of T-joints using both honeycomb sandwich composite and adhesive bonding were suggested to determine the effect of T-joint configuration. It was found that joining with a urethane foam block and overlaminates using the secondary co-bonding technique improves T-joint strength.
Mass Reduction of Transmission Gears for Commercial Vehicles
Shin, Yoo-In ; Shin, Sung-Hwan ; Oh, Tae-Il ; Suh, Jeong-Se ; Song, Chul-Ki ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 3, 2012, Pages 319~323
DOI : 10.7736/KSPE.2012.29.3.319
Transmission is one of the important pars to transmit power from engine to wheels. Mass reduction gears can make the engine power requirement reduce, and can make dynamic performance and fuel efficiency of vehicle improve. Transmission gears are modified for mass reduction without changing their tooth shapes, face widths, and modules by using shape optimization and re-check process. Also structural stability is verified by FEA.
Application Study of Recoil Mechanism using Friction Springs
Cha, Ki-Up ; Gimm, Hak-In ; Cho, Chang-Ki ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 3, 2012, Pages 324~333
DOI : 10.7736/KSPE.2012.29.3.324
The conventional medium and large caliber gun, in general, utilize the hydro-pneumatic recoil mechanism to control the firing impulse and to return to the battery position. However, this kind of mechanism may cause the problems like the leakages and the property changes in oil and gas due to the temperature variations between low and high temperatures. Accordingly, the friction spring mechanism has recently been researched as an alternative system. The friction spring mechanism consists of a set of closed inner and outer rings with the concentric tapered contact surfaces assembled in the columnar form, and can only be used under the compression load. When the spring column is axially loaded, the tapered surfaces become overlapped, causing the outer rings to expand while the inner rings are being contracted in diameter allowing an axial displacement. Because of friction between tapered contact surfaces, much higher spring stiffness is obtained on the stroke at the increase in load than the stroke at the decrease. In this paper, the dynamic equations regarding the friction spring system and the design approach have been investigated. It is also tried for a dynamic model representing the recoil motion and the friction spring forces. And the model has been proved from firing test using a gun system with friction springs. All the results show that the recoil mechanism using friction springs can substitute for the classic hydro-pneumatic recoil system.
Electrical Isolation of Ag Nanowire Film using Femtosecond Laser
Yoon, Ji-Wook ; Park, Jung-Kyu ; Boehme, Daniel ; Zander, Sebastian ; Cho, Sung-Hak ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 3, 2012, Pages 334~338
DOI : 10.7736/KSPE.2012.29.3.334
Electrical isolation of Ag nanowire, which is one of the candidates as electrode for display devices, on polymer with femtosecond pulse laser has been investigated. Line patterning to Ag nanowire with various pulse energy and scan speed were experimented. Duo to the results of the line patterning experiment, we fabricated the isolated squares and measured electrical resistance. The profile of the selectively ablated area was analyzed with AFM(Atomic Force Microscope). The width of the patterned line was
and the depth was
. We demonstrated electrical isolation of the Ag nanowire using femtosecond laser by evaluating the electrical resistance of the sample between isolated and opened area.
Porous Bio-degradable Nano-fiber Machining by Femtosecond Laser
Choi, Hae-Woon ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 3, 2012, Pages 339~345
DOI : 10.7736/KSPE.2012.29.3.339
Electrospun meshed poly-caprolactone PCL was patterned by femtosecond laser with linear grooves. As parametric variables, focus spot size, pulse energy, and scanning speed were varied to determine the affects on groove size and the characteristics of the electrospun fiber at the edges of these grooves. The femtosecond laser was seen to be an effective means for flexibly structuring the surface of ES PCL scaffolds and the width of the ablated grooves was well controlled by laser energy and focus spot size. The ablation threshold was measured to be
which is a little higher than other polymers. These affects were attributed to optical multiple reflections inside nano-fibers. By the laser-induced plasma at higher pulse energies, some melting of fibers was observed.
Gait Pattern Generation for Lower Extremity Exoskeleton Robot and Verification of Energy Efficiency
Kim, Wan-Soo ; Lee, Seung-Hoon ; Ryu, Jae-Kwan ; Baek, Joo-Hyun ; Kim, Dong-Whan ; Han, Jung-Soo ; Han, Chang-Soo ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 3, 2012, Pages 346~353
DOI : 10.7736/KSPE.2012.29.3.346
The purpose of this study is to verify the energy efficiency of the integrated system combining human and a lower extremity exoskeleton robot when it is applied to the proposed gait pattern. Energy efficient gait pattern of the lower limb was proposed through leg function distribution during stance phase and the dynamic-manipulability ellipsoid (DME). To verify the feasibility and effect of the redefined gait trajectory, simulations and experiments were conducted under the conditions of walking on level ground and ascending and descending from a staircase. Experiments to calculate the metabolic cost of the human body with or without the assistance of the exoskeleton were conducted. The energy consumption of the lower extremity exoskeleton was assessed, with the aim of improving the efficiency of the integrated system.