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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 32, Issue 12 - Dec 2015
Volume 32, Issue 11 - Nov 2015
Volume 32, Issue 10 - Oct 2015
Volume 32, Issue 9 - Sep 2015
Volume 32, Issue 8 - Aug 2015
Volume 32, Issue 7 - Jul 2015
Volume 32, Issue 6 - Jun 2015
Volume 32, Issue 5 - May 2015
Volume 32, Issue 4 - Apr 2015
Volume 32, Issue 3 - Mar 2015
Volume 32, Issue 2 - Feb 2015
Volume 32, Issue 1 - Jan 2015
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Taper Tension Logic for Optimization of Residual Stresses in Roll-to-Roll Winding Systems
Lee, Jongsu ; Lee, Changwoo ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 12, 2015, Pages 1011~1016
DOI : 10.7736/KSPE.2015.32.12.1011
In a roll-to-roll continuous system, winding is one of the most important processes since it determines the quality of the final manufactured products such as flexible film and printed electronic devices. Since an adequate winding tension can reduce the incidence of the defects that are derived from the inner stress of the wound roll such as starring and telescoping, it is necessary to determine the optimal taper-tension profile. In this study, an algorithm for the setting of an optimal taper-tension profile in consideration of the residual stress in the wound roll is suggested; furthermore, the algorithm was adjusted for the determination of an optimal taper-tension profile regarding the winding process of
polypropylene (PP) film. As a result of the algorithm-generated, optimal taper-tension profile, the residual stress and radial stress in a PP wound roll were decreased to 27.37 % and 40.05 % (mean value), respectively.
Simulation of Thick Plate Preheating Process Using Induction Heating
Oh, Yong Hee ; Cho, Young Tae ; Jung, Yoon Gyo ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 12, 2015, Pages 1017~1021
DOI : 10.7736/KSPE.2015.32.12.1017
Induction heating has been applied to the preheating process in various industrial fields. It has been used as a simple device structure, limiting the heating zone through controlled variables, and free-welding positions. It would be helpful to weld thick plates with arc welding such as GMAW. The induction heating process is well suited to this process. In this study, in order to find suitable induction heating parameters, a simulation was conducted with multi physics S/W. Three kinds of material were heated by induction coils designed specially for thick plate. Consequently, steel and nimonic alloy were the most efficient materials for preheating by induction. It can be concluded that the induction heating process is a good method for preheating the thick plate.
Analysis of Overlapping Heat Zones in Laser-Assisted Machining
Baek, Jong-Tae ; Lee, Choon-Man ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 12, 2015, Pages 1023~1029
DOI : 10.7736/KSPE.2015.32.12.1023
Laser-assisted machining (LAM) is one of the most effective methods for enhancing the machinability of difficult-to-cut materials, such as titanium alloys and various ceramics, and has been studied by many researchers. LAM is a method that facilitates machining by softening a workpiece using a laser heat source. The advantages of the LAM process are decreases in tool wear, cutting force, and surface roughness. However, when the material is over-heated, melting or burning can occur. This study analyzed the heat source distribution with regard to overlapping of preheating on the laser heating path with an acute angle, a right angle and obtuse angles. Then, a power reduction method was proposed to reduce the melting and burning of the workpiece.
Laser Preheating Method for Three-Dimensional Laser Assisted Milling
Oh, Won-Jung ; Lee, Choon-Man ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 12, 2015, Pages 1031~1037
DOI : 10.7736/KSPE.2015.32.12.1031
Laser assisted machining (LAM) is an effective method with which to effectively process difficult-to-cut materials. Simple machining processes, such as turning and linear tool paths, have been studied by many researchers. But, there are few research efforts on LAM workpieces using threedimensional shapes because of difficulties controlling the laser heat on workpieces with inclined angles or curved surfaces. Two methods for machining three-dimensional workpieces are proposed in this paper. The first is that the heat source shape and laser focal length are maintained using an index table. Second, a rotary type laser module is controlled using an algorithm to move the laser heat source in all directions. This algorithm was developed to control the rotary type laser module and the machine tool simultaneously. These methods are verified by a CATIA simulation.
Study on Improvement of Measurement Precision in Digital Image Correlation Measurement Method by Using Subpixel Algorithms
Kim, Seung Jong ; Kang, Young Jun ; Choi, In Young ; Hong, Kyung Min ; Ryu, Won Jea ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 12, 2015, Pages 1039~1047
DOI : 10.7736/KSPE.2015.32.12.1039
Contact type sensors (e.g., displacement sensor and strain gauge) were typically used to evaluate the safety and mechanical properties in machines and construction. However, those contact type sensors have been constrained because of measurement problems such as surface roughness, temperature, humidity, and shape. The Digital Image Correlation (DIC) measurement system is a vision measurement system. This measurement system uses the taken image using a CCD camera and calculates the image correlation between the reference image and the deformed image under external force to measure the displacement and strain rates. In this paper, we discuss methods to improve the measurement precision of the digital image correlation measurement system. A tensile test was conducted to compare the precision improvement effects, by using the universal test machine and the DIC measurement system, with the use of subpixel algorithms, i.e., the Coarse Fine Search (CFS) algorithm and the Peak Finding (PF) algorithm.
Experimental Study on Different Principles of Variable Stiffness Actuators
Baek, Kyu Yeol ; Kim, HyunGyu ; Seo, TaeWon ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 12, 2015, Pages 1049~1054
DOI : 10.7736/KSPE.2015.32.12.1049
Nowadays, there are many researches involving structural actuators, which have adjustable stiffness; they are also called variable stiffness actuators (VSA). The VSAs can adjust the characteristics of actuators for various functions and human-machine safety. This paper describes the design and analysis of two types of VSAs. To adjust stiffness, the actuators are controlled by a principle of lever ratio mechanism, by changing a pivot position or a spring position in the structure with springs. To make the principle workable, the designs are simplified by using a ball screw system with a motor. Each structure shows different static properties with variable rates of stiffness. We have also shown the experimental verification of the dynamic performance of the two types of VSAs. This research can be applied to various industrial fields, where humans work in conjunction with robots.
Design and Control of the Master Arm for Control of Industrial Robot Arm
Ji, Dae Hyeung ; Jeon, Ji Hye ; Kang, Hyeon Seung ; Choi, Hyeung Sik ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 12, 2015, Pages 1055~1063
DOI : 10.7736/KSPE.2015.32.12.1055
In this paper, a new master arm was developed as an input device of the remote control system for easy control of the industrial robot arm; it has a structure similar to the robot arm and is easy to wear. For control of the slave arm, related equations were derived about the joints between the master and slave arm; and thereby using them, the master arm control system was developed. Furthermore, a control simulator was developed for the convenient and accurate control of the slave arm. Experiments, about controlling the slave arm in applying the master arm, were performed to validate the developed simulator and the derived related equations.
Development of Insole Sensor System and Gait Phase Detection Algorithm for Lower Extremity Exoskeleton
Lim, Dong Hwan ; Kim, Wan Soo ; Ali, Mian Ashfaq ; Han, Chang Soo ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 12, 2015, Pages 1065~1072
DOI : 10.7736/KSPE.2015.32.12.1065
This paper is about the development of an insole sensor system that can determine the model of an exoskeleton robot for lower limb that is a multi-degree of freedom system. First, the study analyzed the kinematic model of an exoskeleton robot for the lower limb that changes according to the gait phase detection of a human. Based on the ground reaction force (GRF), which is generated when walking, to proceed with insole sensor development, the sensing type, location, and the number of sensors were selected. The center of pressure (COP) of the human foot was understood first, prior to the development of algorithm. Using the COP, an algorithm was developed that is capable of detecting the gait phase with small number of sensors. An experiment at 3 km/h speed was conducted on the developed sensor system to evaluate the developed insole sensor system and the gait phase detection algorithm.
Investigation of Structural Safety of Monobloc Tubular Drive Shaft Subjected to Torque
Guk, Dae-Sun ; Ahn, Dong-Gyu ; Lee, Ho-Jin ; Jung, Jong-Hoon ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 12, 2015, Pages 1073~1080
DOI : 10.7736/KSPE.2015.32.12.1073
A drive shaft is used to transmit torque and rotation through the connection of components of a drive train. Recently, a monobloc drive shaft without welding regions is developed to improve the safety of the drive shaft. The drive shaft bears the shear stress induced by torque. The objective of this paper is to investigate into the structural safety of a monobloc tubular drive shaft subjected to torque. Elasto-plastic finite element (FE) analysis is performed to estimate the deformation behavior of the drive shaft and stress-strain distribution in the drive shaft. Several techniques are used to create finite element (FE) model of the monobloc tubular drive shaft subjected to torque. Through the comparison of the results of FE analyses with those of experiments from the viewpoint of rotational angle, appropriate correction coefficients for different load conditions are estimated. The safety of the tubular drive shaft is examined using the results of FE analyses for different load conditions. Finally, it is noted that the designed tubular drive shaft has a sufficient structural safety.
Characteristics of Plastic Lens Dimensional Deviation according to Injection Mold Clamping Force
Yoo, Joong Hak ; Jung, Hyun Suk ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 12, 2015, Pages 1081~1086
DOI : 10.7736/KSPE.2015.32.12.1081
In this paper, it is analyzed the characteristics of plastic lens dimensional deviation according to injection mold clamping force. The influences of fill time, mold clamping force, injection pressure, shear rate, etc., are examined. It was found that mold clamping forces which increased 100, 200, 300, 400, 500 kN can affect the thickness deviation of the lens. Dimensional deviation of the lens derived by injection molding was found to be 2.9% at 100 kN and 0.7% at 500 kN, the smallest observed deviation throughout the study. This indicates that mold clamping force and dimensional deviation of lens thickness were inversely proportional to each other. A prediction of filling time was 1.87 sec performed by injection molding analysis, however, filling time was observed at 1.72 sec in the actual experiment, which is 8.0% shorter than expected. This can be attributed to packing pressure.