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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 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
Silicone Injection Mold & Molding Technology for Super-hydrophobic Curved Surface
Lee, Sung-Hee ; Kang, Jeong-Jin ; Lee, Jong-Won ; Hong, Seok-Kwan ; Ko, Jong-Soo ; Lee, Jae-Hoon ; Noh, Ji-Whan ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 1, 2012, Pages 13~18
DOI : 10.7736/KSPE.2012.29.1.013
In this study, silicone injection molding technology with curved thermoplastic insert was developed to produce super-hydrophobic surface. Thermoplastic insert part and injection mold design of base plastic cover were performed to produce cost effective hydrophobic surface part. An optimization process of part thickness for thermoplastic insert part was performed with transient thermal analysis under silicone over-molding process condition. Structural thermal analysis of silicone injection mold was also performed to obtain uniform temperature condition on the surface of micro-patterned mold core. Super-hydrophobic surface for the silicone injection molded part with thermoplastic insert could be verified from the measurement of contact angle. It was shown that the averaged contact angle was over
Fabrication of a Hybrid Superhydrophobic/superhydrophilic Surface for Water Collection: Gravure Offset Printing & Colloidal Lithography
Ji, Seung-Muk ; Kim, In-Young ; Kim, Eun-Hee ; Jung, Jie-Un ; Kim, Wan-Doo ; Lim, Hyun-Eui ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 1, 2012, Pages 19~24
DOI : 10.7736/KSPE.2012.29.1.019
We demonstrate the desert beetle back mimicking hybrid superhydrophilic/superhydrophobic patterned surface by using the combination method of colloidal lithography and gravure offset printing for nano and micro patterning, respectively. The two methods are cost-effective and industrially available techniques compared to the other nano/micro patterning methods. To verify the water collecting function of the hybrid surface, the water condensation behavior is investigated on the chilled surface in ambient temperature and high humidity. Due to the synergetic effect of drop and film wise condensation, the hybrid superhydrophobic/superhydrophilic surface shows the higher efficiency than one of single wettability surfaces. The work is underway to get the good patterns of hybrid surfaces for water collecting from the dew or fog.
Adaptive Gripper Mimicking Large Deforming Proleg of Hydraulic Skeleton Caterpillar
Jung, Gwang-Pil ; Koh, Je-Sung ; Cho, Kyu-Jin ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 1, 2012, Pages 25~32
DOI : 10.7736/KSPE.2012.29.1.025
In this study, we present a gripping mechanism that is inspired by caterpillar`s proleg. A caterpillar`s proleg has planta that gives compliance to the proleg by greatly deforming its shape. In the bio-inspired gripper, the planta is implemented by flexure joints. The flexures buckle when end force and end moment is applied on the joint in opposite direction. Using this characteristic, the gripping structure is designed so that the flexure buckling can occur. Flexure buckling increases the region where gripping force is constant and this region leads to increasing in gripping range. At the same time, flexure buckling decouples all spines and therefore all spines can move differentially and independently. With this simple but effective mechanism, the bioinspire gripper can achieve adaptive gripping on rough and rugged surfaces. A prototype is built to demonstrate adaptive gripping on rough and rugged surfaces such as cement block, brick.
Development of Scaffold Fabrication System using Multi-axis RP Software Technique
Park, Jung-Whan ; Lee, Jun-Hee ; Cho, Hyeon-Uk ; Lee, Su-Hee ; Park, Su-A ; Kim, Wan-Doo ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 1, 2012, Pages 33~40
DOI : 10.7736/KSPE.2012.29.1.033
The scaffold serves as 3D substrate for the cells adhesion and mechanical support for the newly grown tissue by maintaining the 3D structure for the regeneration of tissue and organ. In this paper, we proposed integrated scaffold fabrication system using multi-axis rapid prototyping (RP) technology. It can fabricate various types of scaffolds: arbitrary sculptured shape, primitive shape, and tube shape scaffolds by layered dispensing biocompatible/ biodegradable polymer strands in designated patterns. In order to fabricate the 3D scaffold, we need to generate the plotting path way for the scaffold fabrication system. We design a data processing program - scaffold plotting software, which can convert the 3D STL file, primitive and tube model images into the NC code for the system. Finally, we fabricated the customized 3D scaffolds with high accuracy using the plotting software and the fabrication system.
Study on the Formation Mechanism of Electroless Plating Seeds on Polymer by Laser
Paik, Byoung-Man ; Lee, Jae Hoon ; Shin, Dong-Sig ; Lee, Kun-Sang ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 1, 2012, Pages 41~47
DOI : 10.7736/KSPE.2012.29.1.041
The LDS(Laser Direct Structuring) is one of the new direct writing methods to fabricate conductive patterns by energy beam. It uses thermoplastic polymers with an additive compound that serves as plating seed after the activation by laser. The advantages of LDS include the miniaturization of electrical components, design flexibility, and a reduced number of production steps. The purpose of this study is to investigate the fundamental mechanism for LDS and the characteristics of conductive patterns by laser parameters. These results were studied by SEM, EDX, and XPS analysis. We have used a 20W pulse-modulated fiber laser and copper electroless plating to fabricate conductive patterns on polymer. The result showed that electroless copper plating seed caused the laser cracking of additive compound. In particular, the additive compound contained in copper metal oxides atoms will be changed to copper metal elements. Also, the characteristics of conductive patterns were dependent on laser parameter, especially laser fluence.
Measurement of Internal Defects of Pressure Vessels using Unwrapping images in Digital Shearography
Kim, Seong-Jong ; Kang, Young-June ; Sung, Yeon-Hak ; Ahn, Yong-Jin ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 1, 2012, Pages 48~55
DOI : 10.7736/KSPE.2012.29.1.048
Pressure vessels in vehicle industries, power plants, and chemical industries are often affected by flaw and defect generated inside the pressure vessels due to production processes or being used. It is very important to detect such internal defects of pressure vessel because they sometimes bring out serious problems. In this paper, an optical defect detection method using digital shearography is used. This method has advantages that the inspection can be performed at a real time measurement and is less sensitive to environmental noise. Shearography is a laser-based technique for full-field, non-contacting measurement of surface deformation (displacement or strain). The ultimate goal of this paper is to detect flaws in pressure vessels and to measure the lengths of the flaws by using unwrapping, phase images which are only obtained by Phase map. Through this method, we could decrease post-processing (next processing). Real length of a pixel can be calculated by comparing minimum and maximum unwrapping images with shearing angle. Through measuring several specimen defects which have different lengths and depths of defect, it can be possible to interpret quantitatively by calculating gray level.
A Study of Automatic Cleaning Tool Design for Façade in High-rise Buildings
Lee, Jin-Koo ; Lee, Dong-Ju ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 1, 2012, Pages 56~63
DOI : 10.7736/KSPE.2012.29.1.056
Due to the development of construction technology, there is a considerable increase in the number of skyscrapers in the world. Accordingly, there are rapid growing requests about maintenance systems such as cleaning, painting, and monitoring the processes of facade in highrise buildings. However, it is extremely dangerous working the walls of high-rise buildings, and crashes from buildings have accounted for large proportion of constructional accidents. An alternative solution must be developed with the commercialization of automatic robot systems. For the last decade, interest in developing robots for cleaning and maintenance in facade of highrise buildings has continuously increased. The use of automatic robot systems can be expected to reduce accidents and decrease labor costs. In this paper, we propose a new kind of cleaning mechanism. We have designed and manufactured various cleaning tools for different types of facades with economic commercialization. The cleaning cycle, size, and intensity will be determined by economic constraints as well. The final goals are to design and manufacture tools and robots that can clean facades efficiently and rapidly even in dangerous places. The cleaning tool systems consist of nozzles, brush rollers, and squeezing devices. Furthermore, these tools and robots perform each process utilizing the systems of built-in guide types and gondola types for building maintenance. The performance of the proposed cleaning tools is evaluated experimentally; however additional study should be necessary for safer and more stable commercialization.
Kinematics Analysis of a 2-DOF Parallel Manipulator
Lee, Jong-Gyu ; Lee, Sang-Ryong ; Lee, Choon-Young ; Yang, Seung-Han ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 1, 2012, Pages 64~71
DOI : 10.7736/KSPE.2012.29.1.064
In this paper, a parallel manipulator is comprised of two sliders and four links. Sliders execute a linear reciprocating motion depending on parallel guides and make the connected links rotate. A couple of links connected by sliders do coupling motion. The end-effector called a link tip has orientation angle. Through the kinematics analysis of this manipulator, we found displacement, velocity and acceleration using direct and inverse kinematics. We used equations that derived from this analysis and determined five constraint conditions. These conditions had much to do with rotation states of links, the relative relation of link length and coupling motion state. To verify those, we suggest a new algorithm regarding constraint conditions of a manipulator. With the result which performed the algorithm, we found out that operation range of coupled links was limited by relative relation of link length and that manipulator was not able to carry out a series of link motion, in case of being the link vertical between two parallel guides.
A Derivation of the Equilibrium Point for a Controller of a Wheeled Inverted Pendulum Running on an Inclined Road
Lee, Se-Han ; Kang, Jae-Gwan ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 1, 2012, Pages 72~78
DOI : 10.7736/KSPE.2012.29.1.072
In this research an equilibrium point of a Wheeled Inverted Pendulum (WIP) running on an inclined road is derived and validated by some experiments. Generally, The WIP has stable and unstable equilibrium point. Only unstable equilibrium point is interested in the research. To keep the WIP on the unstable equilibrium point, the WIP is consistently controlled. A controller for the WIP needs a reference state for the equilibrium point. The reference state can be obtained by studying an equilibrium point of the WIP. This research is deriving dynamic equations of the WIP running on the inclined road and equilibrium of it based on statics. Several experiments are carried out to show the validation of the equilibrium point.
Position Control of Linear Synchronous Motor by Dual Learning
Park, Jung-Il ; Suh, Sung-Ho ; Ulugbek, Umirov ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 1, 2012, Pages 79~86
DOI : 10.7736/KSPE.2012.29.1.079
This paper proposes PID and RIC (Robust Internal-loop Compensator) based motion controller using dual learning algorithm for position control of linear synchronous motor respectively. Its gains are auto-tuned by using two learning algorithms, reinforcement learning and neural network. The feedback controller gains are tuned by reinforcement learning, and then the feedforward controller gains are tuned by neural network. Experiments prove the validity of dual learning algorithm. The RIC controller has better performance than does the PID-feedforward controller in reducing tracking error and disturbance rejection. Neural network shows its ability to decrease tracking error and to reject disturbance in the stop range of the target position and home.
Prediction and Verification of the Twist Deformation of Automotive Structure Parts after Hybrid Welding Using CAE
Lee, Dug-Young ; Choi, Bo-Sung ; Choi, Won-Ho ; Ahn, Jang-Ho ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 1, 2012, Pages 87~95
DOI : 10.7736/KSPE.2012.29.1.087
In recent years, laser-arc hybrid welding has begun to be adopted for assembly welding of automotive bodies and parts, because the hybrid welding process can weld lapped steel sheets having a larger gap than is possible with laser welding. In this paper, to predict the twist deformation by the hybrid welding when brackets are welded in B pillar of a passenger car, the residual stress using CAE is analyzed and the deformation result of CAE is compared with the measured deformation. First of all, after modeling heat source as intended to be expressed with laser-arc hybrid welding method, heat source fitting is done with welding conditions and a section of welding part obtained through specimen test. In case of heat source functions, laser used conical source and arc used double ellipsoid source. Through the local model analysis, elements which are located in the center of the model are selected. The elements are called WME(Welding Macro Element). This WME is extruded in the welding lines and welding phenomenon of complex parts is accomplished. The deformation amount after hybrid welding is got through a simulation, the validity of simulation is verified by measuring the panel and comparing with the simulation result.
Joining Condition of Engineering Plastic for Car
Lee, Jung-Hyun ; Lee, Woo-Ram ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 1, 2012, Pages 96~102
DOI : 10.7736/KSPE.2012.29.1.096
The current establishment of car engineering plastic piping polyethylene (PE) tube used as bonding state or part of the health or safety of fusion is very important. A part of these fusion methods to determine the soundness of the short-term trials and long-term tests can be largely classified. Typical tests included short-term strength, tensile strength, impact strength, compressive strength, resiliency and compression. Polyethylene (PE) pipes installed in the domestic terms of overall penetration rate of 45% has been used. However, polyethylene (PE) pipes have reliability problems, and these occurs mostly in part by defective welding. Therefore, the test is necessary for safety. Non-destructive methods (ultrasonic testing) are difficult to be used. Therefore, Polyethylene (PE) pipe are used. Fusion of thses materilas is necessary in these field however, its technical, and basic research has not been studied well. In this research, short-term strength of welding parts, its tensile strength, hardness, fatigue, and microstructure have been analyzed to find the optimum process conditions to improve mechanical properties.
Numerical Evaluation and Shape Design of Coronary Artery Stent
Kim, Dae-Young ; Lee, Seung-Yeol ; Kim, Heon-Young ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 1, 2012, Pages 103~108
DOI : 10.7736/KSPE.2012.29.1.103
Restenosis symptom, which is well known as a problem of stents, is due to the recoil and expansion pressure depending on shapes of stent. In order to reduce the effect of recoil problem, study on pattern and shape for the stent is required and the expansion pressure and recoil should be evaluated. This paper aims at evaluating mechanical characteristics of stent used in surgery for vessel stenosis. The expansion process of coronary artery stent in vessel for two models including the Cypher
from Johnson & Johnson
and a suggested model were simulated using the Finite Element Analysis. Comparison of the directional recoil simulation results was made. The issues in the deformed shape of vessel and recoil of Cypher
were partially resolved in the suggested model. Therefore, the shape design suggested in this paper was able to reduce the restenosis symptom.
The Life Span of LED by the Rising Glass Transitions Temperature of Epoxy
Ban, Jae-Sam ; Jung, Yong-Ho ; Yang, Hyun-Sam ; Kim, Sun-Jin ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 1, 2012, Pages 109~113
DOI : 10.7736/KSPE.2012.29.1.109
The LED failure rate greatly depends on the physical properties of packaging materials (epoxy). The glass transitions temperature (Tg) of the epoxy is one of the most important physical properties. Therefore, in the present study, various epoxies with high Tg were prepared and their failure shapes were analyzed. In addition, the failure shapes depending on the amount of epoxy and the wire bonding structure were measured. As a consequence, the lower failure rate was obtained with the smaller amount of epoxy. The safety of LED was improved with increasing the Tg of the epoxy.
Curve-typed PMMA Nanochannel Fabrication using Polymer Layer Transfer and Collapse Technique
Cho, Young-Hak ; Kim, Sung-Dong ; Hwang, Ji-Hong ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 1, 2012, Pages 114~120
DOI : 10.7736/KSPE.2012.29.1.114
We present a simple and low-cost method to fabricate poly(methyl-methacrylate) (PMMA) nanochannels with various shapes by combining the standard optical lithography with a PMMA layer transfer and collapse technique. We utilized PMMA membrane reflowing/collapsing phenomena into microchannels to fabricate nanochannels at both corners of arbitrarily-shaped microchannels. This allows nanochannels with various shapes such as curved nanochannels as well as straight nanochannels to be easily fabricated since the shape of the microchannel determines the shape of the nanochannels. This nanochannel fabrication method is simple, flexible, and low-cost since the standard optical lithography with low-resolution optical masks can be used to fabricate nanoscale channels as small as 100 nm wide with various shapes. Also, the sealing of nanochannels can be naturally achieved while the nanochannels are formed through the polymer layer transfer and collapse.
Performance Evaluation of Nano-Lubricants at Thrust Slide-Bearing of Scroll Compressor
Cho, Han-Jong ; Cho, Yong-Il ; Cho, Sang-Won ; Lee, Jae-Keun ; Park, Min-Chan ; Kim, Dae-Jin ; Lee, Kwang-Ho ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 1, 2012, Pages 121~125
DOI : 10.7736/KSPE.2012.29.1.121
This paper presents the friction and anti-wear characteristics of nano-oil with a mixture of a refrigerant oil and carbon nano-particles in the thrust slide-bearing of scroll compressors. Frictional loss in the thrust slide-bearing occupies a large part of total mechanical loss in scroll compressors. The characteristics of friction and anti-wear using nano-oil is evaluated using the thrust bearing experimental apparatus for measuring friction surface temperature and the coefficient of friction at the thrust slide-bearing as a function of normal loads up to 4,000 N and rotating speed up to 3,200 rpm. It is found that the coefficient of friction increases with decreasing rotating speed and normal force. The friction coefficient of carbon nano-oil is 0.023, while that of pure oil is 0.03 under the conditions of refrigerant gas R-22 at the pressure of 5 bars. It is believed that carbon nano-particles can be coated on the friction surfaces and the interaction of nano-particles between surfaces can be improved the lubrication in the friction surfaces. Carbon nano-oil enhances the characteristics of the anti-wear and friction at the thrust slide-bearing of scroll compressors.