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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
Selecting the target year
Roll-to-roll Continuous Manufacturing System for Carbon-Nanotube- / Silver-Nanowire-Based Large-Area Transparent Conductive Film
Park, Janghoon ; Lee, Changwoo ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 8, 2015, Pages 673~680
DOI : 10.7736/KSPE.2015.32.8.673
A roll-to-roll (R2R) continuous manufacturing system for a carbon-nanotube (CNT)-/silver-nanowire (AgNW)- based large-area transparent conductive film was introduced in this study. The systemic guidelines of the R2R slot-die coating process including roll eccentricity, wrap angle, pump accuracy, and blower influence were discussed. To simulate the coating phenomenon, we investigated the governing parameters of the coating process by incorporating the estimated relative thickness that was defined by combining the viscocapillary model and volume model. By using experimental and mathematical approaches, an excellent transparent conductive layer with a
sheet resistance and 88 % transmittance was obtained; moreover, a dimensionless number identifies the correlation between the transparent conductive film and the anti-reflection film.
Welding Characteristics of Lap-Joint Hastelloy C-276 Sheet Metal Using Nd:YAG Laser
Kim, Chan Kyu ; Jung, Yoon Gyo ; Cho, Young Tae ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 8, 2015, Pages 681~685
DOI : 10.7736/KSPE.2015.32.8.681
Hastelloy C-276 composed of Cr, Mo, and Ni is a versatile, corrosion-resistant alloy with numerous industrial applications including its use in nuclear reactors, general chemical plants, and as a superconducting base material. Of especial significance, it can be used as a thin-sheet type whereby lap-joint welding is occasionally necessary. The main welding problems for thin-sheet metals are deformation and burn-through from an excessive heat input. Laser welding can minimize these problems because it has a high energy density and low heat effect on the base material. In this study, the laser-welding characteristics of lap-joint Hastelloy C-276 sheet metal were determined. The criteria of the laser-welding variables were chosen using a heat-conduction analysis, and the optimal welding parameters were selected by experimenting with an Nd:YAG laser.
Study on Accuracy Evaluation of Laser Lens Changer for a Laser-Assisted Machining System
Oh, Won-Jung ; Kim, Eun-Joong ; Lee, Choon-Man ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 8, 2015, Pages 687~692
DOI : 10.7736/KSPE.2015.32.8.687
LAM (Laser-Assisted Machining) is an effective method for processing difficult-to-cut workpieces. The focal length of a LAM system is changed by the change of the workpiece shape during laser preheating; this problem is solved by changing the lens of the laser module. Linear- and rotary-type lens changers were developed to change the laser lens of a LAM system. The linear-type lens changer is operated by a motor with a ball-screw, and the rotary type is operated by a stepping motor. The natural frequency and structural stability of the laser lens changers were confirmed by using a finite element analysis; in addition, the functions of the lens changers were verified by measuring the iterative accuracy. The measured results show that the rotary-type lens changer is more accurate than the linear-type changer.
Study on Structural and Stability Analyses of the Main Parts of a High-Precision Grinding Machine Considering the Cutting Force
Kim, In-Woo ; Lee, Choon-Man ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 8, 2015, Pages 693~698
DOI : 10.7736/KSPE.2015.32.8.693
Recently, the quality of products after the corresponding machining processes were scrutinized in the interest of maintaining a high product-quality standard. The structure and stability of machine tools are important for the prediction of product quality. A structural analysis needs to be carried out to achieve the stable design of machine tools before the initial design stage in the manufacturing process of a precision product. In this study, a structural analysis was carried out using a finite element analysis (FEA) simulation to obtain the design stability of the main parts of a grinding machine. The sizes and locations of both the maximum stress and deformation in consideration of the cutting force of the chuck, tail stock, and bearing of the grinding machine were analyzed. Finally the grinding machine was successfully developed.
Analytical Study of the Determination of Distance between the Laser Heat Source and Tool for Laser-Assisted Machining
Baek, Jong-Tae ; Lee, Choon-Man ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 8, 2015, Pages 699~704
DOI : 10.7736/KSPE.2015.32.8.699
Laser-assisted machining has shown its potential to significantly improve product quality and reduce manufacturing costs; additionally, laser-assisted turning (LAT) and laser-assisted milling (LAM) have been studied by numerous researchers. A research study on the determination of the distance between the laser heat source and the tool for laser-assisted machining, however, has not yet been attempted; we conducted such an analysis by using a finite-element method and heat-transfer equation. The results of this analysis can be used as a reference for the determination of the distance between the laser heat source and the tool for laser-assisted machining.
Study on the Accuracy Improvement of E-ICAM in Consideration of Gouging
Son, Hwang Jin ; Cho, Young Tae ; Jung, Yoon Gyo ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 8, 2015, Pages 705~711
DOI : 10.7736/KSPE.2015.32.8.705
Five-Axis machines can generate undesirable defects such as the undercutting and overcutting errors that frequently occur in the three-axis machining process. It is therefore necessary to develop a program for NC-code generation, whereby the cutter posture is considered to decrease the occurrence of defects. In previous studies, the Easy-Impeller CAM(E-ICAM), an automatic CAM program used for the five-axis machining of impellers, was developed; however, when E-ICAM is used to machine an impeller, it is possible to gouge the hub and blade. Therefore, the aim of this study is the establishment of a formula for each type of endmill to minimize gouging according to the cutter posture, in consideration of several factors that affect accuracy in the machining of an impeller. This study also aimed to improve the performance and accuracy of E-ICAM in the manufacturing of impellers.
Study of the Dynamic Characteristics of a High-Pressure Labyrinth Seal Considering Rotor Whirling
Kim, Chae Sil ; Lee, Kyung Jin ; Shin, Min Jae ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 8, 2015, Pages 713~718
DOI : 10.7736/KSPE.2015.32.8.713
This article describes the calculation procedure for the dynamic characteristics of a high-pressure labyrinth seal wherein the friction force and rotor whirling force are considered; SFCP, the commercial code developed by Lee and two colleagues, is used in the procedure. The simulation results were reviewed in comparison to those of the experiments provided by Benckert; additionally, the SFCP simulation results were verified using the CFD analysis presented by Toshio Hirano. This calculation procedure may therefore be applied to the dynamic characteristics of the labyrinth seals of high-pressure turbo machinery.
Multiple-Axes Velocity-Synchronizing Control of AC-Servomotor Load System for Injection Process
Jon, Yun-Son ; Jung, Kwon ; Choi, Jang Hoon ; Ahn, Hyun ; Lee, Hyeong Cheol ; Kim, Young Shin ; Hong, Seong Ho ; Cho, Seung Ho ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 8, 2015, Pages 719~726
DOI : 10.7736/KSPE.2015.32.8.719
This paper presents a velocity-synchronizing control for the multiple axes of an injection unit; based on MBS, a virtual design model has been developed for the multiple-axes servomechanism. Prior to the design of the controller, a linear plant model was derived via open-loop response simulations. To synchronize the motions of the multiple axes, a cross-type synchronizing controller was designed and combined with the PID control to accommodate any parameter mismatches among the multiple axes. From the tracking control simulations, a significant reduction of both velocity-tracking and position-tracking errors was achieved through the use of the proposed control scheme.
Study of Structural Stiffness of Refrigerator Cabinet Using the Topology Optimization of a Vacuum Insulated Panel (VIP)
Jeong, Gil-Eon ; Kang, Pilseong ; Youn, Sung-Kie ; Yeo, Inseok ; Song, Tae-Ho ; Kim, Jun O ; Kim, Dae Whan ; Kuk, Keon ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 8, 2015, Pages 727~734
DOI : 10.7736/KSPE.2015.32.8.727
Currently, polyurethane (PU) foam is used in most refrigerators as a thermal insulator, whereby the material contributes to structural stiffness by joining the refrigerator cases; however, refrigerator PU foam induces a low thermal efficiency and results in environmental contamination. To resolve these issues, we applied the vacuum insulated panel (VIP) instead of PU form in the design of a new refrigerator type, whereby the VIP significantly contributes to the rectification of the previously mentioned issues. The VIP structure, however, cannot effectively hold refrigerator cases, so the present study investigated a new frame-structure concept by evaluating the stiffness using the topology optimization of refrigerator cases. Lastly, a refrigerator prototype comprising an optimal frame structure was built and subject to a stiffness test, and a comparison of the test results with those of a conventional refrigerator show that the structural stiffness of the prototype is sufficiently effective.
Numerical Analysis of Deformation Mode of Flexible Plate-Type Piezoelectric Module for Evaluating Characteristics of Electrical-Energy Generation
Park, Jeong-Hyun ; Park, Sang-Hu ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 8, 2015, Pages 735~741
DOI : 10.7736/KSPE.2015.32.8.735
Piezoelectric materials are well-utilized for transforming mechanical vibrations into electrical energy that can be stored and used to power a diversity of devices. In this work, these materials have been studied to improve the efficiency of a piezoelectric system, whereby the shape and vibration mode of a piezoelectric module was changed. The basic shape of the piezoelectric module used in this work comprises a width of 10 mm, a length of 30 mm, and a thickness of 0.2 mm. The structural design of the piezoelectric module is optimized using a Taguchi method to increase the corresponding electrical-energy generation. The maximum terminal voltage was defined as a characteristic value to evaluate the optimal design parameters. Through this work, we propose an optimal structure with an eccentric and centric mass; furthermore, the voltage increase of approximately 26% was obtained by comparing a general plate-vibrating piezosystem with an optimal plate-vibrating piezosystem.
Fabrication and Characterization of Array Tactile Actuator Based on Cellulose Acetate
Kim, Hyun-Chan ; Yun, Sungryl ; Ko, Hyun-U ; Kim, Jaehwan ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 8, 2015, Pages 743~748
DOI : 10.7736/KSPE.2015.32.8.743
This paper reports the enhanced fabrication and characterization of a
array tactile actuator composed of cellulose acetate. The array tactile actuator, with dimensions of
, consists of 9 pillar-supported cells made from a cellulose-acetate molding. The fabrication process and performance test along with the results for the suggested actuator are explained. To improve the cell-array fabrication, a laser cut was adopted after the molding process. The displacement of the unit cell increased the input voltage and frequency. Various top masses are added onto the actuator to mimic the touch force, and the acceleration of the actuator is measured under actuation. When 2 kV is applied to the actuator, the maximum acceleration is 0.64 g, which is above the vibrotactile threshold. The actuation mechanism is associated with the electrostatic force between the top and bottom electrodes.
Comparative Analysis of the Right Shoulder's Muscle Activity When Lifting Ipsilateral and Contralateral Legs during the Push Up Plus Exercise
Cho, Sung-hak ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 8, 2015, Pages 749~754
DOI : 10.7736/KSPE.2015.32.8.749
The purpose of this study is to conduct a comparative analysis of the right shoulder's muscle activity when lifting ipsilateral and contralateral legs during the Push Up Plus (PUP) exercise, which is a typical shoulder stabilizing exercise, and to provide effective data for a shoulder stabilization exercise. Upper trapezius, lower trapezius, levator scapula, supraspinatus, infraspinatus, deltoid posterior, serratus anterior and pectoralis major, which are eight main muscles of a shoulder, were analyzed for the left and right leg lifting by using an electromyogram (EMG). The study revealed that the muscle activities of the right shoulder's upper trapezius, levator scapula, supraspinatus, serratus anterior and pectoralis major were higher when lifting an ipsilateral (right side) leg, compared to lifting a contralateral (left side) leg. Therefore, lifting an ipsilateral leg can be an effective method for enhancing the maneuverability (mobility) of the right shoulder when lifting a single leg.
Combinatorial Physical Stimulation and Synergistically-Enhanced Fibroblast Differentiation for Skin Regeneration
Ko, Ung Hyun ; Hong, Jungwoo ; Shin, Hyunjun ; Kim, Cheol Woong ; Shin, Jennifer H. ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 8, 2015, Pages 755~760
DOI : 10.7736/KSPE.2015.32.8.755
For proper wound healing, dermal contraction and remodeling are critical; during the natural healing process, differentiated fibroblasts called "myofibroblasts" typically undertake these functions. For severe wounds, however, a critical mass of dermal matrix and fibroblasts are lost, making self-regeneration impossible. To overcome this impairment, synthetic wound patches with embedded functional cells can be used to promote healing. In this study, we developed a polydioxanone (PDO)-based cell-embedded sheet on which dermal fibroblasts were cultured and induced for differentiation into myofibroblasts, whereby the following combinatorial physicochemical stimuli were also applied: aligned topology, electric field (EF), and growth factor. The results show that both the aligned topology and EF synergistically enhanced the expression of alpha smooth-muscle actin (
-SMA), a key myofibroblast marker. Our proof-of-concept (POC) experiments demonstrated the potential applicability of a myofibroblast-embedded PDO sheet as a wound patch.