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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 33, Issue 9 - Sep 2016
Volume 33, Issue 8 - Aug 2016
Volume 33, Issue 7 - Jul 2016
Volume 33, Issue 6 - Jun 2016
Volume 33, Issue 5 - May 2016
Volume 33, Issue 4 - Apr 2016
Volume 33, Issue 3 - Mar 2016
Volume 33, Issue 2 - Feb 2016
Volume 33, Issue 1 - Jan 2016
Selecting the target year
Development of Manufacturing System Package for CFRP Machining
Kim, Hyo-Young ; Kim, Tae-Gon ; Lee, Seok-Woo ; Yoon, Han-Sol ; Kyung, Dae-Su ; Choi, In-Hue ; Choi, Hyun ; Ko, Jong-Min ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 6, 2016, Pages 431~438
DOI : 10.7736/KSPE.2016.33.6.431
Recently, concerns about the environment are becoming more important because of global warming and the exhaustion of earth's resources. In the aviation and automobile industries, the application of light materials is increasingly important for eco-friendly and effective. Carbon Fiber Reinforced Plastics is a composite material which great formability and the high strength of carbon fiber. CFRP, which is both light and strong, is hard to manufacture. In addition, CFRP machining has a high chance of defects. This research discusses the development of a manufacturing system package for CFRP machining. It involving CFRP Drilling/Water-jet Manufacturing Machines, Inspection/Post-processing Systems, CNC platform for an EtherCAT servo Communication, Flexible Manufacturing Systems and CFRP machining Processes.
Evaluation of Machining Characteristics of the Carbon Fiber Reinforced Plastic (CFRP) Composite by the Orthogonal Cutting
Kim, Yeong Bin ; Kim, Min Ji ; Park, Hyung Wook ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 6, 2016, Pages 439~445
DOI : 10.7736/KSPE.2016.33.6.439
Carbon fiber reinforced plastic (CFRP) composites have been widely used due to their great strength, stiffness and light weight. However, due to its anisotropy and inhomogeneous properties the machining process of CFRP composites is typically more complex than that of regular metals. Since there are many defects, such as delamination and tool wear during the machining process of CFRP composites, the optimization of this process is essential in improving the productivity. In this study, orthogonal machining of CFRP composites was performed to identify the machining characteristics of these materials. In addition, an experimental observation of delamination was investigated through the use of scanning electron microscopy (SEM). In these experiments, the cutting forces were measured and analyzed to determine the difference between machining of CFRP composites and metals. The comparison between the numerical models and experimental results was performed in terms of the maximum cutting forces.
3-Axis Milling Algorithm Development for Carbon Fiber Reinforced Polymer (CFRP) Composites
Luo, Shan ; Bayesteh, Reza ; Dong, Zuomin ; Jun, Martin B.G. ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 6, 2016, Pages 447~452
DOI : 10.7736/KSPE.2016.33.6.447
The simulation of Carbon fiber reinforced polymer (CFRP) machining facilitates the selection of optimal cutting parameter for high machining efficiency and better surface quality. In this study, This paper proposes a dual-dexel model to represent the fiber laminate with computational geometry method to calculate the fiber length removed per revolution and fiber cutting angles. A flat end milling simulation software is developed in C# to simulate and display the CFRP milling process. During simulation, fiber lengths, fiber cutting angle and engaged cutting angle can be displayed in real-time. A CFRP plate with different angles in different layer is used to compare the simulation results.
CFRP Drilling Experiments: Investigation on Defect Behaviors and Material Interface Detection for Minimizing Delamination
Kim, Gyuho ; Ha, Tae In ; Lee, Chan-Young ; Ahn, Jae Hoon ; Kim, Joo-Yeong ; Min, Byung-Kwon ; Kim, Tae-Gon ; Lee, Seok-Woo ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 6, 2016, Pages 453~458
DOI : 10.7736/KSPE.2016.33.6.453
CFRP (Carbon Fiber Reinforced Plastic) and CFRP-metal stacks have recently been widely used in the aerospace and automobile industries. When CFRP is machined by a brittle fracture mechanism, defect generation behaviors are different from those associated with metal cutting. The machining quality is strongly dependent on the properties of CFRP materials. Therefore, process control for CFRP machining is necessary to minimize the defects of differently manufactured CFRPs. In this study, defects in drilling of CFRP substrates with a variety of fiber directions and resin types are compared with respect to thrust force. An experimental study on material interface detection is carried out to investigate its benefits in process control.
Measurements of Defects after Machining CFRP Holes Using High Speed Line Scan
Kim, Teaggyum ; Kyung, Daesu ; Son, Unchul ; Park, Sun-Young ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 6, 2016, Pages 459~467
DOI : 10.7736/KSPE.2016.33.6.459
Using a line scan camera and a Galvano mirror, we constructed a high-speed line-scanning microscope that can generate 2D images (
) without any moving parts. The line scanner consists of a Galvano mirror and a cylindrical lens, which creates a line focus that sweeps over the sample. The measured resolutions in the x (perpendicular to line focus) and y (parallel to line focus) directions are both
, with a 2X scan lens and a 3X relay lens. This optical system is useful for measuring defects, such as spalling, chipping, delamination, etc., on the surface of carbon fiber reinforced plastic (CFRP) holes after machining in conjunction with adjustments in the angle of LED lighting. Defects on the inner wall of holes are measured by line confocal laser scanning. This confocal method will be useful for analyzing defects after CFRP machining and for fast 3D image reconstruction.
Study on Effects of Foam-Filter for Reduction of Air-Trapping in Large-Size Sand Gravity Casting
Yu, Jae Hyun ; Lee, Ho Rim ; Joo, Jeong A ; Hwang, Yun Je ; Shin, Bo Sung ; Park, Sang Hu ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 6, 2016, Pages 469~475
DOI : 10.7736/KSPE.2016.33.6.469
In this work, casting processes, such as filling and solidification, were simulated in order to accurately predict volume shrinkage defects in large-sized sand gravity casting. Turbulent flow of melted materials and a difference of solidification speed can cause volume shrinkage defects. In order to solve this problem and to understand the phenomenon, a porous filter application was studied. Two different porosities of 10 and 20 p.p.i filters were introduced into the gating system, and in view of the results so far achieved, the defect was dramatically reduced by 22%, compared to that without the use of the filter.
Study on Spring-Back Effect according to Roll Gap and Forming Velocity of Roll Forming Process
Kim, Dong Hong ; Yoon, Dae-Hwan ; Seol, Sang-Seok ; Jung, Dong Won ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 6, 2016, Pages 477~483
DOI : 10.7736/KSPE.2016.33.6.477
The spring-back and bow phenomenon in the roll forming process are important factors regarding the accuracy of evaluation of production goods. The purpose of this study was to determine the influence of spring-back and bow phenomenon according to the main variables (forming velocity and roll gap). The material of the forming sheet was high tension steel (SPFH 590), which has been used commonly in recent years. In order to accurately measure the spring-back and bow phenomenon, the forming sheet was formed into a V-shape. The study was applied to OFAT (One Factor at a Time) experimentation, with respect to the experimental variables (the forming speed and the roll gap). In the experimental results, the forming speed had a small influence on the spring-back and bow phenomenon. However, the roll gap had a greater influence on the springback and the bow phenomenon, as opposed to the forming speed.
Effect of Reference Current and Depth of Cut on Electro-Discharge Energy in Electro-Discharge Truing Process for Metal-Bonded Grinding Wheel
Shin, Gun-Hwi ; Kwak, Tae-Soo ; Jung, Myung-Won ; Kwak, Ihn-Sil ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 6, 2016, Pages 485~490
DOI : 10.7736/KSPE.2016.33.6.485
This study focused on developing an electro-discharge truing method for the ELID grinding process using a metal-bonded grinding wheel. The truing process in grinding plays important roles in enhancing the quality of the ground surface. In this study, a reference current in the electro-discharge truing process was confirmed to be a viable solution for efficient truing through performance experiments. Current and voltage variation experiments were carried out and the variation output data were collected with a monitoring program to understand the electrodischarge phenomenon that occurs between metal-bonded grinding wheels and copper electrodes. The experimental results showed that as the reference current decreased, the average electro-discharge energy decreased. Therefore, the reference current can be used as an indicator to estimate the size of the gap between the truer and grinding wheel.
Development of Annular Optics for the Inspection of Surface Defects on Screw Threads Using Ray Tracing Simulation
Lee, Jiwon ; Lim, Yeong Eun ; Park, Keun ; Ra, Seung Woo ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 6, 2016, Pages 491~497
DOI : 10.7736/KSPE.2016.33.6.491
This study aims to develop a vision inspection system for screw threads. To inspect external defects in screw threads, the vision inspection system was developed using front light illumination from which bright images can be obtained. The front light system, however, requires multiple side images for inspection of the entire thread surface, which can be performed by omnidirectional optics. In this study, an omnidirectional optical system was designed to obtain annular images of screw threads using an image sensor and two reflection mirrors; one large concave mirror and one small convex mirror. Optical simulations using backward and forward ray tracing were performed to determine the dimensional parameters of the proposed optical system, so that an annular image of the screw threads could be obtained with high quality and resolution. Microscale surface defects on the screw threads could be successfully detected using the developed annular inspection system.
Study on Performance Prediction of Electric Propulsion System for Multirotor UAVs
Jeong, Jinseok ; Byun, Youngseop ; Song, Woojin ; Kang, Beomsoo ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 6, 2016, Pages 499~508
DOI : 10.7736/KSPE.2016.33.6.499
This paper describes a study of performance prediction of an electric propulsion system for multirotor UAVs. The electric propulsion system consists of motors, propellers, batteries and speed controllers, and significantly affects performance characteristics of the platform. The performance of the electric propulsion system for multirotor UAVs was predicted using an analytical model derived from the characteristics of each component, operation experiments and statistical analyses. Ground performance tests and endurance flights were performed to verify the reliability of the proposed performance prediction method. A quadrotor platform was designed to demonstrate the parcel delivery service used in the endurance flight. From the result of verification tests, it was confirmed that the proposed method has a good agreement.
Dynamic Performance Evaluation of Blood Flow Simulator Based on Windkessel Models
Chun, Sejong ; Jin, Jonghan ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 6, 2016, Pages 509~516
DOI : 10.7736/KSPE.2016.33.6.509
A blood flow simulator is one of the experimental devices used to better understand the cardiovascular system. Time-Domain analysis is not sufficient to understand the cardiovascular system because of the effects related to pulsating flows. Even when the mean pressure and mean flow rate of the blood flow simulators are satisfied, the dynamic properties can differ from the desired performance. In this paper, the Windkessel model, a well-known mathematical model of the cardiovascular system, was employed to obtain optimized pressure using initial values. The Windkessel parameters, including flow resistance, R, are expected to lead to a better understanding of the dynamic behavior of cardiovascular systems.
Signal Analysis of Inverter-Type Outdoor Unit for Detecting Operation Changes of Commercial Refrigerator
Lim, Hyo Joon ; Lee, Ju Kyoung ; Hwang, Jun Hyeon ; Lee, Kyung Chang ; Lee, Suk ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 6, 2016, Pages 517~523
DOI : 10.7736/KSPE.2016.33.6.517
Unlike household refrigerators, commercial refrigerators are composed of separate indoor and outdoor units. The outdoor unit of most commercial refrigerators is designed to run at a fixed speed, which results in low energy efficiency and loud fan noise. Moreover, it cannot respond flexibly to changing thermal load in the indoor unit. Inverter type outdoor units can address such problems through speed changes based on information obtained from the indoor unit. However, using two units from different manufacturers is often not a viable solution. If condition changes in the indoor unit can be detected without communication between the two units, it is possible to adjust the speed of the outdoor unit. This paper attempts to analyze the signal from the outdoor unit when the condition of the indoor unit changes by varying the thermal load.