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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
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Analysis and Optimization on Inside Flows of Fluid in Roll-to-Roll Slot-Die Nozzle by CFD Simulation
Kim, Seongyong ; Lee, Changwoo ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 8, 2016, Pages 611~616
DOI : 10.7736/KSPE.2016.33.8.611
Computational fluid dynamic simulation based on the ABAQUS software was conducted to observe the inside flow of slot-die nozzle. The slot-die nozzle was modeled as 3-dimensional structure and three significant parameters were determined: inlet velocity of fluid, reservoir angles, number of strips none of which have been mentioned previously in the literature. The design of experiment, full factorial analysis was performed within determined design and process levels. The simulation result shows the inlet fluid velocity is most significant factor for the flows of inside nozzle. As an interaction effect, reservoir angle is closely related with number of strip that should address when the nozzle is designed. Moreover, the optimized values of each determined parameter were obtained as 35 mm/s of inlet velocity, 3 of strip numbers, and
of reservoir angles. Based on these parameters, the outlet velocity was obtained as 0.53% of outlet uniformity which is improved from 8.67% of nominal results.
A Study on the Dynamic Stability of Observation Antenna Considering Rotational Speed by Payload Drive Motor
Kim, Chae Sil ; Shin, Min Jae ; Keum, Chang Min ; Kim, Jae Min ; Choi, Hun Oh ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 8, 2016, Pages 617~622
DOI : 10.7736/KSPE.2016.33.8.617
The article describes the determination of the dynamic stability for an observation antenna, considering the rotational speed by the payload driving motor. A finite element model of the observation antenna was made using the solid and beam elements. The connecting parts between the solid and the beam was adequately coupled. The boundary conditions were made by restriction of the degree of freedoms in the supporting points. With the comparison between the modal analysis results and the rotating speed of the payload driving motor, no resonance for the structure of antenna was identified and first natural frequency was determined under 33 Hz (Seismic Cut-Off Frequency). Therefore, the dynamic stability of the antenna was confirmed by the comparism between the seismic safety criterion and the stress results of the dynamic analysis applied the loading conditions and required response spectrum (RRS).
A Study on the Dynamic Stability of Heavy Press Considering Rotational Speed
Shin, Min Jae ; Kim, Chae Sil ; Keum, Chang Min ; Kim, Jae Min ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 8, 2016, Pages 623~628
DOI : 10.7736/KSPE.2016.33.8.623
This article describes the determination of the dynamic stability for a heavy press, particularly considering rotational speed. A finite element model of the driving parts for the heavy press was generated. We also applied boundary conditions and dynamic loads considering the driving conditions. Modal analysis was conducted using the finite element construction model. Therefore, no resonance was identified with the comparison between the results of the modal analysis and vibration excitation frequency by the gear tooth. In addition, the stress distribution of the driving parts for press was determined using transient analysis. As compared to the yield strength of the material, the dynamic stability the heavy press was confirmed.
An Analytical Study on the Preheating Effect of Flat Workpiece in Thermally Assisted Machining by Multi Heat Sources
Moon, Sung-Ho ; Lee, Choon-Man ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 8, 2016, Pages 629~634
DOI : 10.7736/KSPE.2016.33.8.629
Laser-assisted machining (LAM) is one of the most effective methods of processing difficult-to-cut materials, such as titanium alloys and various ceramics. However, it is associated with problems such as the inability of the laser heat source to generate an appropriate preheating temperature. To solve the problem, thermally assisted machining with multiple heat sources is proposed. In this study, thermal analysis of multiple heat sources by laser and arc is performed according to power, heat source size, and leading heat source position. Then, the results are analyzed according to each condition. The results of this analysis can be used as a reference to predict preheating temperature in thermally assisted machining with multiple heat sources.
A Study on the Development of Forming Process for a Compressor Shell Body
Kim, Min-Jeong ; Oh, Won-Jung ; Shin, Dong-Cho ; Lee, Choon-Man ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 8, 2016, Pages 635~640
DOI : 10.7736/KSPE.2016.33.8.635
The shell body is the main exterior part of a compressor, and production of shell bodies has increased along with a growing demand for air conditioners, refrigerators, air compressors, and so on. Cracks frequently occur in the process of welding a shell body. In this study, a deep drawing process for creating a shell body from a blank is developed. The technique consists of a four-step deep drawing and a two-step trimming process. Analysis is performed by DEFORM software to examine the safety of the deep drawing and trimming processes. The deep drawing process for the shell body developed in this study would have wide application in many industrial fields.
A Method of Wood Section Measuring and the Image Calibration Using Line Laser
Kim, Gi Hwan ; Park, Min Su ; Kim, Do Yeop ; Lee, Suk Yong ; Lee, Eung Suk ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 8, 2016, Pages 641~646
DOI : 10.7736/KSPE.2016.33.8.641
The best method of measuring wood diameter is a contact-type device: however, obtaining an accurate result can be problematic under certain circumstances. In this study, we used a laser beam and a CCD camera that did not require contact with wood. The wood is illuminated by the laser beam, and the CCD camera captures this illumination. The measurement results were determined by processing of the captured image sequences. This paper explains the use of image processing and laser systems for measurement of wood under circumstances in which physical contact is impossible.
Variable Impedance Control and Fuzzy Inference Based Identification of User Intension for Direct Teaching of a Mobile Robot
Ko, Jong Hyeon ; Bae, Jang Ho ; Hong, Daehie ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 8, 2016, Pages 647~654
DOI : 10.7736/KSPE.2016.33.8.647
Controlling a mobile robot using conventional control devices requires skill and experience, and is not intuitive, especially in complex environments. For human-mobile robot cooperation, the direct-teaching method with impedance control has been used most frequently in complex environments. This thesis proposes a new direct-teaching method for a mobile robot utilizing variable impedance control. This includes analysis of user intention, which is changed by force and moment. A fuzzy inference technique is proposed in this thesis for identification of user intension. The direct teaching of a mobile robot based on variable impedance control through fuzzy inference is experimentally verified by comparing its efficiency to that of the conventional impedance control-based direct teaching of a mobile robot. Experimental data, such as the total time consumed, path error time, and the total energy used by the user, were recorded. The results showed that the efficiency of variable impedance control was increased.
Effects of Design Parameters on the Ergonomic Quality of a Self-Closing Drawer
Seo, Man Cheol ; Kim, Kwon Hee ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 8, 2016, Pages 655~660
DOI : 10.7736/KSPE.2016.33.8.655
Self-closing drawers are used in high-end products, such as furniture, home appliances, and a range of other storage devices. In this study, a self-closing mechanism is proposed. A system consisting of a friction latch, constant force spring, rotary damper with rack, and pinion is developed. The retracting drawer can be latched at any position and can be reactivated by simple touch. The constant force spring and rotary damper offer smooth closing action. The ergonomic quality of the closing action is quantified by an index based on velocity-time behavior. The effects of various design parameters are analyzed with a dynamics model and experimentally validated by prototype testing.
Development of an Advanced Oil Deflector Used in Thermoelectric Power Plant
Choi, Yong Hoon ; Kwak, Hyo Seo ; Lee, Chang Ryeol ; Kim, Chul ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 8, 2016, Pages 661~668
DOI : 10.7736/KSPE.2016.33.8.661
Oil deflector prevents oil leakage that occurs in thermoelectric power plant at operating lubricant facilities. Vibration of rotating rotor-induced wear of aluminum tooth in existing oil deflector leads to oil leakage as well as life shortening of the tooth. In this study, an advanced oil deflector was developed for shock absorption and prevention of wear by decreasing clearance (from 0.5 mm to 0.2 mm) between rotor and tooth to minimize oil leakage, and by replacing 2 aluminum teeth in outmost of the oil deflector with hi-performance seal made of engineering plastic. The CFD results were compared between advanced vs. existing oil deflector to determine the amount of oil loss. Structural safety was verified through impact analyses according to the three kinds of engineering plastics, considering cost efficiency, and optimal material of hi-performance seal was chosen.
Constraint Analysis and Reduction of Over-Constraints for Tolerance Design of Assemblies - A Case Study of Ball Valve Design
Park, Jun Il ; Yim, Hyunjune ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 8, 2016, Pages 669~681
DOI : 10.7736/KSPE.2016.33.8.669
Mechanical designers often make mistakes that result in unwanted over-constraints, causing difficulty in assembly operations and residual stress due to interference among parts. This study is concerned with detection and elimination of over-constraints. Screw theory is a general method that is used for constraint analysis of an assembly and motion analysis of a mechanism. Mechanical assemblies with plane-plane, pin-hole, and pin-slot constraint pairs are analyzed using screw theory to illustrate its utility. As a real-world problem, a ball valve design is analyzed using the same method, and several unwanted over-constraints are detected. Elimination measures are proposed. Nominal dimensions of some parts are adjusted, and dimensions and tolerances of the pins and holes are modified using the virtual condition boundary concept. The revised design is free of over-constraints. General procedure for applying screw theory to constraint analysis is established and demonstrated; it will contribute to improving quality of assembly designs.
Servo Mismatch Estimation of Miniaturized Machine Tools Using Laser Tracker
Lee, Hoon Hee ; Kweon, Sung Hwan ; Son, Jin Gwan ; Yang, Seung Han ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 8, 2016, Pages 683~689
DOI : 10.7736/KSPE.2016.33.8.683
Servo mismatch, which affects positioning accuracy of multi-axis machine tools, is usually estimated via the circular test. However, due to mechanical restrictions in measuring instruments, the circular test using a double ball-bar is difficult to apply in miniaturized or super-large sized machine tools. Laser trackers are widely used to measure the form accuracy of parts and the positioning accuracy of driving systems. In this paper, a technique for the servo mismatch estimation of multi-axis machine tools is proposed via the circular test using a laser tracker. To verify the proposed technique, experiments using a double ball-bar and laser tracker are conducted in a 3-axis machine tool. The difference in the evaluation results is 0.05 msec. The servo mismatch for the miniaturized machine tool is also evaluated using the proposed technique.
Study on the Nanoscale Behavior of ALD Pt Nanoparticles at Elevated Temperature
An, Jihwan ;
Journal of the Korean Society for Precision Engineering, volume 33, issue 8, 2016, Pages 691~695
DOI : 10.7736/KSPE.2016.33.8.691
This paper covers the investigation of the microscale behavior of Pt nanostrucures fabricated by atomic layer deposition (ALD) at elevated temperature. Nanoparticles are fabricated at up to 70 ALD cycles, while congruent porous nanostructures are observed at > 90 ALD cycles. The areal density of the ALD Pt nanostructure on top of the SiO2 substrate was as high as 98% even after annealing at
for 1hr. The sheet resistance of the ALD Pt nanostructure dramatically increased when the areal density of the nanostructure decreased below 85 - 89% due to coarsening at elevated temperature.