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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 31, Issue 12 - Dec 2014
Volume 31, Issue 11 - Nov 2014
Volume 31, Issue 10 - Oct 2014
Volume 31, Issue 9 - Sep 2014
Volume 31, Issue 8 - Aug 2014
Volume 31, Issue 7 - Jul 2014
Volume 31, Issue 6 - Jun 2014
Volume 31, Issue 5 - May 2014
Volume 31, Issue 4 - Apr 2014
Volume 31, Issue 3 - Mar 2014
Volume 31, Issue 2 - Feb 2014
Volume 31, Issue 1 - Jan 2014
Selecting the target year
Effects of Packing Parameter on Plastic Article Dimensions in the Plastic Injection Molding
Kim, Bum Joon ; Shin, Ju Kyung ; Lee, Jeong Goo ; Sohn, Il Seon ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 1, 2014, Pages 9~13
DOI : 10.7736/KSPE.2014.31.1.9
The molding process can be divided into five separate steps: plastification, injection, holding, cooling, and finally ejection. In the plastic injection molding, the effect factor such as mold temperature, injection speed, packing pressure and inhomogeneous cooling under packing process affects both the article dimension and physical characteristics. Especially, the packing pressure is the most critical factor to affect molded articles quality among the packing parameters. In this paper, the CAE simulation considering the molding condition is performed to predict the faulty cause which appears in the packing process between cavities of injection molding machine. From the results of CAE simulation, the packing phenomena according to the product form and the gate position was investigated to improve the article quality and minimize the various molding defects. The effect of packing pressure and gate number on the injection molding was discussed.
Design Technique for Improving the Durability of Top Coating for Thermal Barrier of Gas Turbine
Koo, Jae-Mean ; Seok, Chang-Sung ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 1, 2014, Pages 15~20
DOI : 10.7736/KSPE.2014.31.1.15
Thermal barrier coating (TBC) is used to protect the substrate and extend the operating life of the gas turbine for a power plant and an aircraft. The major cause of failure of such a coating is the spallation of coating, and it results from the thermal stress between top coating and bond coating. To improve the durability of TBC system, the dense vertical cracked (DVC) coating method to insert vertical cracks is applied to a gas turbine blade. In this study, a criterion for the design of vertical crack in the DVC coating was presented using the finite element analysis.
A Study on Tensile Behavior of Transparent Polycarbonate (PC) Plate in the High Temperature
Lee, Ho Jin ; Ahn, Dong-Gyu ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 1, 2014, Pages 21~28
DOI : 10.7736/KSPE.2014.31.1.21
Recently, several researchers made their endeavor to manufacture the photobioreactor(PBR) with characteristic shapes form vacuum and blow forming process. Hence, behaviors of the transparent polycarbonate(PC) plate in the high temperature region should be examined to obtain the desired PBR case via vacuum and blow forming processes. The aim of this paper is to investigate tensile behavior of PC plate in the high temperature. Various tensile tests were performed using high temperature tensile testing machine. The influence of tensile speed, thickness and ambient temperature on tensile behavior in the high temperature was examined. The flow stress and tensile strength augmented when the tensile speed increased. In order to obtain proper flow curves with strain rate effects for different temperature of specimen, G'sell-Jonas model was adopted. The material constants of the G'sell-Jonas model were estimated. The flow curves of the PC plate considering the tensile speed, specimen thickness and temperature were obtained.
Study on Temperature Effect of Difficulty-to-Cut Material in Laser Heat Treatment Process
Kim, Dong Hong ; Jung, Dong Won ; Lee, Choon-Man ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 1, 2014, Pages 29~33
DOI : 10.7736/KSPE.2014.31.1.29
Recently, Difficult-to-cut materials are used in many manufacturing industry. But the difficult-to-cut materials are difficult-to-cutting process. So difficult to cut material cutting process was used after heat treatment through preheating for easy cutting process. In this study, Inconel 625 was preheating using laser heat source in computer simulation. Laser heat source temperature applied
that suitable preheating temperature for Inconel 625. And temperature effects such as temperature distribution for moving heat source studied apply to similar actual process condition. Simulation results for heat treatment effects through temperature distribution verified.
A Study on the Machinability Evaluation According to Lubrication Conditions and Taper Angle for Turning of SCM440
Choi, Min-Seok ; Kim, Dong-Hyeon ; Hwang, Seong-Ju ; Lee, Choon-Man ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 1, 2014, Pages 35~42
DOI : 10.7736/KSPE.2014.31.1.35
Recently, in industry field, many researchers are looking for ways to reduce the use of lubricant because of environmental and economical reasons. MQL lubrication is one of many lubrication technologies. The aim of this study is to evaluate the machinability considering lubrication methods and taper angles of workpieces for turning of SCM440. Workpieces of two shapes such as workpiece with and without taper angle are used. And two lubrication methods such as MQL and Wet have been considered. And cutting force and surface roughness are used as characteristic values. Cutting speed, feed rate, injection angle and distance are used as design parameters. The characteristic values were statistically analyzed by Taguchi method. From the results, main effects plot and importance of each parameter according to conditions are analyzed. Finally, this study has been suggested the optimum machining conditions according to the lubrication methods, machining conditions and shape of workpiece.
Traveling Performance of a Robot Platform for Unmanned Weeding in a Dry Field
Kim, Gook-Hwan ; Kim, Sang-Cheol ; Hong, Young-Ki ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 1, 2014, Pages 43~50
DOI : 10.7736/KSPE.2014.31.1.43
This paper introduces a robot platform which can do weeding while traveling between rice seedlings stably against irregular land surface of a paddy field. Also, an autonomous navigation technique that can track on stable state without any damage of the seedlings in the working area is proposed. Detection of the rice seedlings and avoidance knocking down by the robot platform is achieved by the sensor fusion of a laser range finder (LRF) and an inertial measurement unit (IMU). These sensors are also used to control navigating direction of the robot to keep going along the column of rice seedling consistently. Deviation of the robot direction from the rice column that is sensed by the LRF is fed back to a proportional and derivative controller to obtain stable adjustment of navigating direction and get proper returning speed of the robot to the rice column.
Multiple Axes Position Synchronizing Control of Hydraulic-Cylinder Load System for Clamping Process
Cho, Seung Ho ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 1, 2014, Pages 51~57
DOI : 10.7736/KSPE.2014.31.1.51
This paper presents a synchronizing adaptive feedforward control for clamping servomechanism of injection molding machines. Based on MBS, virtual design model has been developed for a direct forcing clamping mechanism. A synchronizing controller is designed and combined with adaptive feedforward control to accommodate mismatches between the real plant and the linear plant model used. From tracking control simulations, it is shown that significant reduction in position tracking error is achieved through the use of proposed control scheme.
Tolerance Analysis and Design of Refrigerator Door System for Functional and Aesthetic Quality of Gap and Flush
Kim, Jinsu ; Kim, Jae-Sung ; Yim, Hyunjune ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 1, 2014, Pages 59~66
DOI : 10.7736/KSPE.2014.31.1.59
The central seam, the vertical 'line' between doors, in the front view of a refrigerator must have its gap and flush within certain ranges to meet functional and aesthetic requirements. The conventional criteria for gap and flush control in the industry are to keep the gap and flush within certain ranges at each of various points along the seam. For aesthetics, however, the uniformity of the gap is also as important because a 'tapered' seam is negatively perceived by human eyes. This paper shows a case study of tolerance design for a refrigerator door system. It presents a step-by-step procedure, which consists of datum flow chain analysis, identification of assembly features, computer modeling of feature tolerances, assembly operations and measurements, tolerance simulation, and tolerance adjustments based on the simulation results. It is found that extra care may need to be used to satisfy the aesthetical criterion for gap uniformity.
A Study on the Failure and Life Assessment of High Speed Spindle
Lee, Tae Hong ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 1, 2014, Pages 67~73
DOI : 10.7736/KSPE.2014.31.1.67
A reliability evaluation or prediction can be defined as MTBF which stands for mean time between failures (Exclusively for repairable failures). Spindle system has huge effect on performance of machine tools and working quality as well as is required of high reliability. Especially, it takes great importance in producing automobiles which includes a large number of working processes. However, it is unusually difficult to predict reliability because there are lack of data and research about reliability of spindle system. Standards and methods of examinations for reliability evaluation of machine tools are scarce at local and abroad as well. Therefore, this research is meant to improve the reliability of spindle system before mass produced with developing standards of reliability and methods of examinations through FMEA to assess reliability of spindle system in prototype stages of developing high speed spindle system of machining center.
Glass Drilling using Laser-induced Backside Wet Etching with Ultrasonic Vibration
Kim, Hye Mi ; Park, Min Soo ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 1, 2014, Pages 75~81
DOI : 10.7736/KSPE.2014.31.1.75
Laser beam machining has been known as efficient for glass micromachining. It is usually used the ultra-short pulsed laser which is time-consuming and uneconomic process. In order to use economic and powerful long pulsed laser, indirect processing called laser-induced backside wet etching (LIBWE) is good alternative method. In this paper, micromachining of glass using Nd:YAG laser with nanosecond pulsed beam has been attempted. In order to improve shape accuracy, combined processing with magnetic stirrer has been widely used. Magnetic stirrer acts to circulate the solution and remove the bubble but it is not suitable for deep hole machining. To get better effect, ultrasonic vibration was applied for improving shape accuracy.
Implementation of High Performance Micro Electrode Pattern Using High Viscosity Conductive Ink Patterning Technique
Ko, Jeong Beom ; Kim, Hyung Chan ; Dang, Hyun Woo ; Yang, Young Jin ; Choi, Kyung Hyun ; Doh, Yang Hoi ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 1, 2014, Pages 83~90
DOI : 10.7736/KSPE.2014.31.1.83
EHD (electro-hydro-dynamics) patterning was performed under atmospheric pressure at room temperature in a single step. The drop diameter smaller than nozzle diameter and applied high viscosity conductive ink in EHD patterning method provide a clear advantage over the piezo and thermal inkjet printing techniques. The micro electrode pattern was printed by continuous EHD patterning method using 3-type control parameters (input voltage, patterning speed, nozzle pressure). High viscosity (1000cps) conductive ink with 75wt% of silver nanoparticles was used. EHD cone type nozzle having an internal diameter of
was used for experimentation. EHD jetting mode by input voltage and applied 1st order linear regression in stable jet mode was analyzed. The stable jet was achieved at the amplitude of 1.4~1.8 kV.
micro electrode pattern was created at optimized parameters (input voltage 1.6kV, patterning speed 25mm/sec and nozzle pressure -2.3kPa).
A Droplet-Manipulation Method using Opto-thermal Flows on Amorphous Silicon Thin Film
Lee, Horim ; Yoon, Jin Sung ; Kim, Dong Sung ; Lim, Geunbae ;
Journal of the Korean Society for Precision Engineering, volume 31, issue 1, 2014, Pages 91~96
DOI : 10.7736/KSPE.2014.31.1.91
We present a droplet-manipulation method using opto-thermal flows in oils. The flows are originated from Marangoni and buoyancy effects due to temperature gradient, generated by the adsorption of light on an amorphous silicon thin film. Using this method, we can transport, merge and mix droplets in an extremely simple system. Since the temperature rise during the operation is small, this method can be used for biological applications without the damage on cell viability.