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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 27, Issue 12 - Dec 2010
Volume 27, Issue 11 - Nov 2010
Volume 27, Issue 10 - Oct 2010
Volume 27, Issue 9 - Sep 2010
Volume 27, Issue 8 - Aug 2010
Volume 27, Issue 7 - Jul 2010
Volume 27, Issue 6 - Jun 2010
Volume 27, Issue 5 - May 2010
Volume 27, Issue 4 - Apr 2010
Volume 27, Issue 3 - Mar 2010
Volume 27, Issue 2 - Feb 2010
Volume 27, Issue 1 - Jan 2010
Selecting the target year
An analysis of Cutting Characteristic of Multilayer FPCB using Nd:YAG UV Laser System
Choi, Kyung-Jin ; Lee, Young-Hyun ;
Journal of the Korean Society for Precision Engineering, volume 27, issue 3, 2010, Pages 9~17
The FPCB is used for electronic products such as LCD display. The process of manufacturing FPCB includes a cutting process, in which each single FPCB is cut and separated from the panel where a series of FPCBs are arrayed. The most-widely used cutting method is the mechanical punching, which has the problem of creating burrs and cracks. In this paper, the cutting characteristics of the FPCB have been experimented using Nd:YAG DPSS UV laser as a way of solving this problem. To maximize the industrial application of this laser cutting process, test samples of the multilayered FPCB have been chosen as it is actually needed in industry. The cutting area of the FPCB has four different types of layer structure. First, to cut the test sample, the threshold laser cut-off fluence has been found. Various combinations of laser and process parameters have been made to supply the acquired laser cut-off fluence. The cutting characteristics in terms of the variation of the parameters are analyzed. The laser and process parameters are optimized, in order to maximize the cutting speed and to reach the best quality of the cutting area. The laser system for the process automation has been also developed.
Optical Analysis of Diffraction Grating and Fresnel Zone Plate Fabricated on Fused Silica Glass by a Femtosecond Laser
Ryu, Jin-Chang ; Kim, Jin-Tae ; Sohn, Ik-Bu ;
Journal of the Korean Society for Precision Engineering, volume 27, issue 3, 2010, Pages 18~26
Diffraction gratings with precise spatial periods of 2
have been fabricated by using a femtosecond laser which does not have limits on materials of micromachining and small thermal effects due to high peak power. Diffraction angle and diffraction efficiency of those were measured. Simulation results of diffraction angle and diffraction efficiency of the diffraction grating calculated with the parameters such as line width, depth, and spatial period of the fabricated gratings were compared with experimental results measured with a He-Ne laser. Besides these, Fresnel Zone Plates (FZPs) with focal distances of 50 mm and 25 mm were fabricated and focal distances of fabricated FZP were measured. Those experimental results for diffraction gratings and FZPs match well with experimental results.
Ultra Miniature Eddy Current Sensor with 3 Axes for On-Machine-Measurement
Kim, Sun-Ho ;
Journal of the Korean Society for Precision Engineering, volume 27, issue 3, 2010, Pages 27~32
The OMM(On-Machine-Measurement) system has many advantages compare to conventional measurement in the way the time and cost. But, the sensor suitable to OMM system is restrictive use. Touch trigger probe sensor has long time for measurement and non-contact sensor has directional demerit. Because the long mechanical parts such as gear and lead screw for pump, injector and machine tools has big and heavy, unclamp and transferring for measurement in machining process is very difficult. This paper presents a development of ultra miniature eddy current displacement sensor with 3 axes for On-Machine-Measurement system. The accuracy of the sensor is experimentally proved in the grinding machine. In experimental results, the accuracy has under
Fundamental Theory on the Zeros Distribution of Multizeros Optical Beam for Longrange Optical Measurement Applications
Fujimoto, Ikumatsu ; Sato, Seichi ; Kurihara, Toru ; Ando, Sigeru ; Kim, Min-Young ;
Journal of the Korean Society for Precision Engineering, volume 27, issue 3, 2010, Pages 33~40
Multizeros(multiple order zeros) optical beams which belong to the Laguerre-Gaussian beams, have rotational phase and conically-shaped amplitude structures around multizeros points in their phase and amplitude profiles, respectively. Especially, they have their own characteristics that the multizero points do not vanish over free-space propagation. Therefore, they are expected to be adequate for the applications of long-range optical measurement by using their multizero points as optical markers for the deformation sensing. In this paper, fundamental properties of multizeros optical beams for long-range optical measurement applications are investigated and clarified. In particular, the mathematical investigations are described on the characteristics of multizeoros optical beams such as (1) separation of a multizero into isolated single order zeros, (2) topological charge of zeros distribution which are induced by superposing them. And also the outline of a fundamental experiment and its result are explained briefly.
Experiments on Robust Nonlinear Control for Brush Contact Force Estimation
Lee, Byoung-Soo ;
Journal of the Korean Society for Precision Engineering, volume 27, issue 3, 2010, Pages 41~49
Two promising control candidates have been selected to test the sinusoidal reference tracking performance for a brush-type polishing machine having strong nonlinearities and disturbances. The controlled target system is an oscillating mechanism consisting of a common positioning stage of one degree-of-freedom with a screw and a ball nut driven by a servo motor those can be obtained commercially. Beside the strong nonlinearity such as stick-slip friction, the periodic contact of the polishing brush and the work piece adds an external disturbance. Selected control candidates are a Sliding Mode Control (SMC) and a variant of a feedback linearization control called Smooth Robust Nonlinear Control (SRNC). A SMC and SRNC are selected since they have good theoretical backgrounds, are suitable to be implemented in a digital environment and show good disturbance and modeling uncertainty rejection performance. It should be also noted that SRNC has a nobel approach in that it uses the position information to compensate the stickslip friction. For both controllers analytical and experimental studies have been conducted to show control design approaches and to compare the performance against the strong nonlinearity and the disturbances.
Orthogonality Calibration of a High Precision Stage using Self-calibration Method
Kim, Ki-Hyun ; Park, Sang-Hyun ; Kim, Dong-Min ; Jang, Sang-Don ;
Journal of the Korean Society for Precision Engineering, volume 27, issue 3, 2010, Pages 50~57
A high precision air bearing stage has been developed and calibrated. This linear-motor driven stage was designed to transport a glass or wafer with the X and Y following errors in nanometer regime. To achieve this level of precision, bar type mirrors were adopted for real time
laser measurement and feedback control. With the laser wavelength variation and instability being kept minimized through strict environment control, the orthogonality of this type of control system becomes purely dependent upon the surface flatness, distortion, and assembly of the bar mirrors. Compensations for the bar mirror distortions and assembly have been performed using the self-calibration method. As a result, the orthogonality error of the stage was successfully decreased from
to 2.48 arcsec.
Remanufacturing Industry for Automobile Parts of USA
Mok, Hak-Soo ; Jeon, Chang-Su ; Han, Chang-Hyo ; Skerlos, Steven J. ; Kim, Hyung-Ju ; Lee, Kyu-Chang ;
Journal of the Korean Society for Precision Engineering, volume 27, issue 3, 2010, Pages 58~65
Remanufacturing is a process that restores old products to perform like new, while saving energy, reducing consumption of natural resources, and lowering environmental emissions. By extending the product life cycle, remanufacturing approaches enable closed loop material cycles that are ultimately necessary for a sustainable society. This paper provides some description of the current automotive remanufacturing enterprise, with a particular emphasis on key vehicle components that are currently remanufactured. The analysis yields two major conclusions. First, volume of the USA automotive after sales and remanufacturing industry market is estimated. Second, market price of a remanufactured component in the automotive sector is surprisingly uncorrelated with the number of companies engaged in remanufacturing that component - at least for companies registered with the Automotive Parts Remanufacturing Association (ARPA).
A Study on the Effect of Metal Plate Position Design on Mechanical Strength during Lap Joint Dissimilar Friction Stir Welding Process of Aluminum Alloys
Park, Hee-Sang ; Ko, Jun-Bin ; Choi, Won-Doo ; Choi, Man-Young ;
Journal of the Korean Society for Precision Engineering, volume 27, issue 3, 2010, Pages 66~72
Recently, the use of means of transportation of the lightweight aluminum to temper the trend is increasing. More efficient use of lightweight aluminum material to Friction stir welding has been widely attempted. Types of welding tools at the right screw to rotate anti-clockwise direction, when the tensile stress exerted on the location of the top plate to the left in the direction of the welding process to the installation was able to obtain high tensile strength. A5052 to the top of the left in the direction of the welding process to install and, when you installed the right under the A6061 was not easily come up to the top of the A5052. Conversely, at the bottom left to install on top of the A6061 and A5052 have been installed at the bottom of the upper area of the A6061 and A5052 intrude easily form the shape of the hill you can see that it was formed.
Preliminary Study on Development of Length-Variable Rotor Blade for Unmanned Helicopter
Chun, Ju-Hong ; Byun, Young-Seop ; Lee, Byoung-Eon ; Song, Woo-Jin ; Kim, Jeong ; Kang, Beom-Soo ;
Journal of the Korean Society for Precision Engineering, volume 27, issue 3, 2010, Pages 73~79
A preliminary study on a length-variable rotor blade for a small unmanned helicopter has been conducted. After surveys on previous researches, and examining requirements for application to a small unmanned helicopter, a length-variable rotor blade was designed and manufactured to be driven by centrifugal force from rotor revolution with no mechanical actuator. The rotor blade was divided into a fixed inboard section and an outboard section sliding in span-wise direction. In order to determine the operating conditions of the length-variable rotor during revolution, and to derive the design variables of extension spring and rotor weight, a series of analyses from multi-body dynamics solution were conducted. The manufactured prototype was verified of its length-varying mechanism from a rotor stand, the results and required future improvements are discussed.
Finite Element Simulation of Surface Pitting due to Contact Fatigue
Rhee, Hwan-Woo ; Kim, Sung-Hun ;
Journal of the Korean Society for Precision Engineering, volume 27, issue 3, 2010, Pages 80~88
A simple computational model for modeling of subsurface crack growth under cyclic contact loading is presented. In this model, it is assumed that the initial fatigue crack will initiate in the region of the maximum equivalent stress at certain depth under the contacting surface. The position and magnitude of the maximum equivalent stress are determined by using the equivalent contact model, which is based on the Hertzian contact conditions with frictional forces. The virtual crack extension method is used for simulation of the fatigue crack growth from the initial crack up to the formation of the surface pit due to contact fatigue. The relationships between the stress intensity factor and crack length are then determined for various combinations of equivalent contact radii and loadings.
Development of Operating Mechanism of a Pretensioner using Internal Gear Pairs
Jung, Sung-Pil ; Park, Tae-Won ; Kim, Wook-Hyeon ; Hong, Yo-Sun ;
Journal of the Korean Society for Precision Engineering, volume 27, issue 3, 2010, Pages 89~94
The pretensioner is used to retract the belt webbing and tighten up any slack in the event of a crash. The retracting force of the pretensioner helps move the passenger into the optimum crash position in his or her seat. In this paper, the new concept of an operating mechanism of the pretensioning system is presented. The internal gear design program is developed using MATLAB. Two kinds of numerical analysis model are created. The first one, the rigid body dynamic model, is used to estimate the performance of several gear pairs. The initial performance of the new operating mechanism is analyzed and the best combination of the gear pairs is selected. The second one, the structural dynamic model, is used to calculate the deformation of the gear teeth. To decrease the deformation and interference of the teeth, the shape of the gear pairs is changed.
Analysis on Aerodynamic Characteristics of Drying Process in R2R Printed Electronics
Seo, Yang-Ho ; Chang, Young-Bae ; Kim, Chang-Wan ;
Journal of the Korean Society for Precision Engineering, volume 27, issue 3, 2010, Pages 95~103
Roll to Roll (R2R) is one of the most promising production technologies in the printed electronics such as OLEDs, e-paper, backplanes, RFID because this technology can save production cost and increase production speed. Printed electronics includes various processes such as printing, drying, winding, unwinding, and so on. In printed electronics R2R system, air-flotation oven is employed for drying process. Therefore, it is essential to introduce efficient and fast drying process when printing is finished. This paper considers the analysis of drying process in R2R that involves hot air flow. Air-flotation oven consists of non-contact supports and drying of coated web materials such as plastic films and paper. In this paper, experimental results and numerical analysis of pressure-pad air bar are investigated. The aerodynamic characteristics of pressure-pad air bar are numerically calculated using computational fluid dynamics (CFD) approach. Then the measured values of the aerodynamic forces for air bars are compared with those of CFD analysis.
Numerical Analysis of Cyclic Deformation of Polymer Foam Film Using Stretched Truncated Octahedron Model
Yoo, Ui-Kyung ; Lee, Young-Seog ;
Journal of the Korean Society for Precision Engineering, volume 27, issue 3, 2010, Pages 104~110
Cyclic deformations of polymer foam film are simulated using the finite element method. Material of polymer foam film is polypropylene (PP). The calculated polymer foam film is micro-scale thin film has cellular structure. The polymer foam film is used in ferro-electret applications. The polymer foam film is idealized to one cell structure as lens shaped stretched truncated octahedron model. Cyclic deformation is performed by uniaxial stretching. Stretching direction is perpendicular to plane of cellular film. Various cyclic strain amplitudes, pore wall thicknesses, pore shape are investigated to find deformation tendency of cellular structure. Consequently, cellular structure has various macroscopic stresses on cyclic deformation with various pore thickness and pore shape.
A Study on the Stiffness Characteristic of Repeated Unit Cell Structure
Park, Soo ; Seon, Kwang-Sang ; Koo, Jae-Mean ; Seok, Chang-Sung ; Park, Tae-Jung ;
Journal of the Korean Society for Precision Engineering, volume 27, issue 3, 2010, Pages 111~117
The repeated unit cell structure is applied to the composite, the carbon nano tube and sandwich panel. In this paper, a study on the stiffness of unit cell structure has been performed with the tube support plate of the steam generator. For this, repeated unit cell structure's equivalent elastic constant and poisson's ratio was evaluated through FEA and tests under the elastic range load. Also we evaluated the effect on the specimen size from results.
Development of Automated Mechanical Transmission Model to Evaluate TCU Control Logic
Oh, Joo-Young ; Song, Chang-Sub ;
Journal of the Korean Society for Precision Engineering, volume 27, issue 3, 2010, Pages 118~126
The automated mechanical transmission(AMT) is composed of electronic control management(ECM) and automatic shift gear(ASG). The AMT has advantages which are high efficiency of manual transmissions(MT) and offer operation convenience similar to automatic transmissions(AT). However, it has defects that are the torque gap during gear shift transients and shift time is long. To reduce such defects, it is necessary practically to evaluate error and characteristics as developing simulation model before the control algorithm is applied. In this paper, models are composed of vehicle model and AMT shift control model. Particularly AMT shift control model consists of main clutch management model (MCM) and shift control management model(SCM). The developed models were verified by comparing the simulated and experimental results under the same operational conditions. It can also be used to evaluate shift algorithm.
Assessment of Creep Damage on a High Temperature Pipe Bend of 0.5Cr0.5Mo0.25V Ferritic Steel for Thermal Power Plant
Hyun, Jung-Seob ; Heo, Jae-Sil ; Kim, Bong-Soo ;
Journal of the Korean Society for Precision Engineering, volume 27, issue 3, 2010, Pages 127~134
Components in thermal power plants are subjected to service conditions under which creep damages take place causing material exhaustion. Comprehensive creep damage investigations have been performed on a 0.5Cr0.5Mo0.25V pipe bend which had been taken out of service after 117,603h and 501 start-ups because of severe cracks. The propagation of creep damage in a long term exposed pipe bend has been analysed by the replication, Indentation and hardness tests. Also, Calculation of creep lifetime has been investigated in order to verify actual lifetime of a damaged pipe bend. By measuring diametrical expansion, Accumulated creep strain and creep strain rate were calculated. Calculated results of creep lifetime on the Larson-Miller Parameter method are good agreement with actual service-exposed hour.
Development of a Multi-material Stereolithography System
Kim, Ho-Chan ; Choi, Jae-Won ; Wicker, Ryan ;
Journal of the Korean Society for Precision Engineering, volume 27, issue 3, 2010, Pages 135~141
Researchers continue to explore possibilities for expanding additive manufacturing (AM) technologies into direct product manufacturing. One limitation is in the materials available for use in AM that can meet the needs of end-use applications. Stereolithography (SL) is an AM technology well known for its precision and high quality surface finish capabilities. SL builds parts by selectively crosslinking or solidifying photo-curable liquid resins, and the resin industry has been continuously developing new resins with improved performance characteristics. This paper introduces a unique SL machine that can fabricate parts out of multiple SL materials. The technology is based on using multiple vats positioned on a rotating vat carousel that contain different photo-curable materials. To change the material during the process, the build platform is raised out of the current vat, a new vat with a different material is rotated under the platform, and the platform is submerged into the new vat so that the new material can be used. This paper introduces a new vat exchange mechanism, cleaning process, recoating process, resin leveling mechanism and process planning technologies for the implementation of multiple material SL. An overview of the system framework is provided and the system integration and control software is described. In addition, several multiple material test parts are designed, fabricated, and described.