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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Precision Engineering
Journal Basic Information
Journal DOI :
Korean Society of Precision Engineering
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Volume & Issues
Volume 30, Issue 12 - Dec 2013
Volume 30, Issue 11 - Nov 2013
Volume 30, Issue 10 - Oct 2013
Volume 30, Issue 9 - Sep 2013
Volume 30, Issue 8 - Aug 2013
Volume 30, Issue 7 - Jul 2013
Volume 30, Issue 6 - Jun 2013
Volume 30, Issue 5 - May 2013
Volume 30, Issue 4 - Apr 2013
Volume 30, Issue 3 - Mar 2013
Volume 30, Issue 2 - Feb 2013
Volume 30, Issue 1 - Jan 2013
Selecting the target year
Effect of Surface Treatment on Fatigue Strength of SCM440H
Yeom, Hyunho ; Lee, Moon Gu ; Lee, Choon Man ; Jeon, Yongho ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 8, 2013, Pages 779~784
DOI : 10.7736/KSPE.2013.30.8.779
Increased efficiency and improved performance associated with light-weight materials were investigated in this study. Numerous studies have investigated surface treatments to improve the fatigue strength of metals. Laser heat treatment is a promising method because the power and spot size can be easily controlled, allowing a small heat affected zone (HAZ). However, changes in the material properties can result; in particular, the material can become more brittle. In this study, a combination of laser heat treatment and vibration peening was proposed to increase fatigue strength without changing the material characteristics. SCM440H was investigated experimentally, and specimens were tested using a giga-cycle ultrasonic fatigue tester. The results show that the combination of these two processes significantly increased the fatigue strength and, furthermore, different fracture types were observed after a small and large number of cycles.
Design of a Reduction Gear using Double-Enveloping Worm Gear
Kim, Tae Woo ; Hwang, Young Kug ; Lee, Choon Man ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 8, 2013, Pages 785~789
DOI : 10.7736/KSPE.2013.30.8.785
Worm gear sets may be either single- or double-enveloping. In a single-enveloping set, the worm wheel is cut into a concave surface, thus partially enclosing the worm when meshed. The double-enveloping worm gear is similar to the single-enveloping gear; however, the worm envelopes the worm gear. Thus both are throated. The double-enveloping worm gear has more of the tooth surface in contact than the single-enveloping worm gear. The larger contact area increases the load-carrying capacity. For this reason, double-enveloping worm gearing is widely applied in heavy-duty machinery, for applications including construction and metallurgy. In this paper, we designed a compact reduction gear that is highly efficient using double-enveloping worm gears. We calculated the bearing load in the worm gearing to select the bearing and the housing surface area according to the recommended values from AGMA(American Gear Manufacturers Association). The finite element method was used to assess the structural integrity.
Investigation on Vibration Characteristics of Micro Speaker Diaphragms for Various Shape Designs
Kim, Kyeong Min ; Kim, Seong Keol ; Park, Keun ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 8, 2013, Pages 790~796
DOI : 10.7736/KSPE.2013.30.8.790
Micro-speaker diaphragms play an important role in generating a desired audio response. The diaphragm is generally a circular membrane, and the cross section is a double dome, with an inner dome and an outer dome. To improve the sound quality of the speaker, a number of corrugations may be included in the outer dome region. In this study, the role of these corrugations is investigated using two kinds of finite element method (FEM) calculations. Structural FEM modeling was carried out to investigate the change in stiffness of the diaphragm when the corrugations were included. Modal FEM modeling was then carried out to compare the natural frequencies and the resulting vibrational modes of the plain and corrugated diaphragms. The effects of the corrugations on the vibration characteristics of the diaphragm are discussed.
Roll Forming Analysis for High Strength Steel Bumper Process
Kim, Dong Hong ; Jung, Dong Won ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 8, 2013, Pages 797~801
DOI : 10.7736/KSPE.2013.30.8.797
Today's automotive industry is evolving toward low-emissions or zero-emissions high-efficiency vehicles. Highly efficient power sources are required, as well as high strength steels for various parts to increase safety. In this study, we investigated the roll-forming process for the development of high strength, lightweight steel bumper beams. The roll-forming process was analyzed using the software package Shape-RF in combination with a rigid-plastic finite element method model. An optimal roll-forming process based on roll-pass was obtained using finite element method simulations.
Top Coating Design Technique for Thermal Barrier of Gas Turbine
Koo, Jae-Mean ; Lee, Si-Young ; Seok, Chang-Sung ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 8, 2013, Pages 802~808
DOI : 10.7736/KSPE.2013.30.8.802
Thermal barrier coating (TBC) is used to protect substrates and extend the operating life of gas turbines in power plant and aeronautical applications. The major causes of failure of such coatings is spallation, which results from thermal stress due to a thermal expansion coefficient mismatch between the top coating and the bond coating layers. In this paper, the effects of the material properties and the thickness of the top coating layer on thermal stresses were evaluated using the finite element method and the equation for the thermal expansion coefficient mismatch stress. In addition, we investigated a design technique for the top coating whereby thermal resistance is exploited.
Relationship Between Small-punch Creep Test Data and Uniaxial Creep Test Data based on the Monkman-Grant Relation
Kim, Bum Joon ; Sohn, Ilseon ; Lim, Byeong Soo ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 8, 2013, Pages 809~814
DOI : 10.7736/KSPE.2013.30.8.809
The relationship between the small-punch creep test and the conventional creep test was investigated experimentally using a method similar to that of the Monkman-Grant relationship. Uniaxial and small-punch creep rupture tests were carried out on 9Cr-2W ferritic steel (Commercial Grade 92 steel: X10CrWMoVNb 9-2) at elevated temperatures. From the relation derived in the same manner as the Monkman-Grant relation, a correlation between the displacement rate in response to the small-punch creep test and the strain rate in the uniaxial creep test was found, and the creep life was calculated using this relation. Furthermore, the failure modes of the small punch creep test specimens were investigated to show that the fracture was caused by creep.
Determination of Optimum Blank Shape to Minimize the Root Gap during TIG Welding in Hot Curvature Forming of Al5083 Thick Plate
Lee, Jeong Min ; Ko, Dae Hoon ; Lee, Kyung Hun ; Lee, Chan Joo ; Kim, Byung Min ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 8, 2013, Pages 815~823
DOI : 10.7736/KSPE.2013.30.8.815
The hot curvature forming of large aluminum plates is a process used to produce spherical liquefied natural gas (LNG) tanks. In this study, we describe a method to determine the optimum shape of blanks to minimize the root gap in the forming process. The method proposed in this study was applied to a small-scale model for thick plates with a curvature of 1500 mm and thickness of 6 mm. First, the shape of the curved shells was determined as the target shape, and then a coordinate transform was used to determine the optimum blank shape, which was then iteratively modified using the results of finite element method (FEM) simulations, including heat transfer, until the shape error was minimized. Experiments in forming using Al5083 thick plate were carried out, showing that the method can determine the optimum blank shape within an allowable root gap of 0.1 mm.
Design of a Robust Controller for the Butterfly Valve with Considering the Friction
Choi, Jeongju ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 8, 2013, Pages 824~830
DOI : 10.7736/KSPE.2013.30.8.824
We propose a tracking control system for butterfly valves. A sliding mode controller with a fuzzy-neural network algorithm was applied to the design of the tracking control system. The control scheme used the real-time update law for the unmodeled system dynamics using a fuzzy-neural network algorithm. The performance of the proposed control system was assessed through a range of experiments.
Design of Temperature based Gain Scheduled Controller for Wide Temperature Variation
Jeong, Jae Hyeon ; Kim, Jung Han ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 8, 2013, Pages 831~838
DOI : 10.7736/KSPE.2013.30.8.831
This paper focused on the design of an efficient temperature controller for a plant with a wide range of operating temperatures. The greater the temperature difference a plant has, the larger the nonlinearity it is exposed to in terms of heat transfer. For this reason, we divided the temperature range into five sections, and each was modeled using ARMAX(auto regressive moving average exogenous). The movement of the dominant poles of the sliced system was analyzed and, based on the variation in the system parameters with temperature, optimal control parameters were obtained through simulation and experiments. From the configurations for each section of the temperature range, a temperature-based gain-scheduled controller (TBGSC) was designed for parameter variation of the plant. Experiments showed that the TBGSC resulted in improved performance compared with an existing proportional integral derivative (PID) controller.
A Study on Oil Path Design in the Journal Bearing of a Reciprocating Compressor
Cho, Ihn Sung ; Jung, Jae Youn ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 8, 2013, Pages 839~846
DOI : 10.7736/KSPE.2013.30.8.839
Because the performance of a reciprocating compressor in refrigeration and air-conditioning systems is influenced by the lubrication characteristics of sliding components, the lubrication characteristics between the crankshaft and journal bearing have to be researched for the design and the performance improvement of reciprocating compressors. Thus, the proper supply of lubricant for a lubrication between the crankshaft and journal bearing is essential, and an oil path for lubricant supply is installed in the shaft or bearing. However, in order to guarantee the lubrication performance of the journal bearing, it is necessary to design the position of the oil path. Therefore, it is studied to find the optimum position of the oil path by the analysis of the pressure distribution in the journal bearing. The results show that the position of the oil path is significantly influenced by the pressure distribution of the oil film in the journal bearing.
The Effect of Reduction of Friction Heat by Micro Dimple on the Sliding Surface of Elastomer
Kim, Gun Wan ; Yoo, Myung Ho ; Lee, Taek Sung ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 8, 2013, Pages 847~853
DOI : 10.7736/KSPE.2013.30.8.847
Micro-dimples on sliding surfaces have been investigated to reduce the frictional forces on metal bearing surfaces; however, for an elastomer, such as thermoplastic polyurethane (TPU), this has not been studied. The material properties of an elastomer are affected by temperature, and this can shorten the life of the elastomer. In this paper, micro-dimples were applied on the surface of an elastomer in order to reduce the frictional heating, which was experimentally investigated using pin-on-disk apparatus while the surface temperature was measured. To obtain optimal design parameters, the design of the experiment was applied, and the shape of the section, size, depth and density of micro-dimples were selected as the design parameters. The results show that the size of the dimple is the most important design parameter.
Effects of Bearing Arrangement on the Dynamic Characteristics of High-speed Spindle
Hong, Seong-Wook ; Choi, Chun-Seok ; Lee, Chan-Hong ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 8, 2013, Pages 854~863
DOI : 10.7736/KSPE.2013.30.8.854
High-speed spindle systems typically employ angular contact ball bearings, which can resist both axial and radial loading, and exhibit high precision and durability. We investigated the effects of the arrangement of the angular contact ball bearings on the dynamics of high-speed spindle systems. The spindle dynamics were studied with a number of spindle-bearing models, and the location of the bearings was varied, along with the rotational speed and the preload. A finite element spindle model and a bearing model were used, and simulated data showed that the bearing arrangement significantly affected the spindle dynamics. Furthermore, the main effects were due to the cross coupling terms between the transverse and rotational motions of the ball bearings. The coupling stiffness terms were found to influence the spindle dynamics, depending on the mode shapes. An extensive discussion is provided on the effects of the bearing arrangement on the dynamics of the spindle.
Friction Reduction Properties of Evaporation Coated Petroleum and Silicone Oil Lubricants
Yoo, Shin Sung ; Kim, Dae Eun ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 8, 2013, Pages 864~869
DOI : 10.7736/KSPE.2013.30.8.864
As the size of mechanical components decreases, capillary forces and surface tension become increasingly significant. A major problem in maintaining high reliability of these small components is that of large frictional forces due to capillary action and surface tension. Unlike the situation with macro-scale systems, liquid lubrication cannot be used to reduce friction of micro-scale components because of the excessive capillary and drag forces. In this work, the feasibility of using evaporation to coat a thin film of organic lubricant on a solid surface was investigated with the aim of reducing friction. Petroleum and silicone oils were used as lubricants to coat a silicon substrate. It was found that friction could be significantly reduced and, furthermore, that the effectiveness of this method was strongly dependent on the coating conditions.
Development of the MVS (Muscle Volume Sensor) for Human-Machine Interface
Lim, Dong Hwan ; Lee, Hee Don ; Kim, Wan Soo ; Han, Jung Soo ; Han, Chang Soo ; An, Jae Yong ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 8, 2013, Pages 870~877
DOI : 10.7736/KSPE.2013.30.8.870
There has been much recent research interest in developing numerous kinds of human-machine interface. This field currently requires more accurate and reliable sensing systems to detect the intended human motion. Most conventional human-machine interface use electromyography (EMG) sensors to detect the intended motion. However, EMG sensors have a number of disadvantages and, as a consequence, the human-machine interface is difficult to use. This study describes a muscle volume sensor (MVS) that has been developed to measure variation in the outline of a muscle, for use as a human-machine interface. We developed an algorithm to calibrate the system, and the feasibility of using MVS for detecting muscular activity was demonstrated experimentally. We evaluated the performance of the MVS via isotonic contraction using the KIN-COM
equipment at torques of 5, 10, and 15 Nm.
Curing Characteristics for Projection Stereolithography based on LCD and Visible LED
Kim, Ga Young ; Ha, Young Myoung ; Park, In Baek ; Kim, Min Sub ; Jo, Kwang Ho ; Lee, Seok Hee ;
Journal of the Korean Society for Precision Engineering, volume 30, issue 8, 2013, Pages 878~884
DOI : 10.7736/KSPE.2013.30.8.878
Stereolithography can be classified into two main categories according to the cross-sectional shape: scanning type and projection type. Projection stereolithography has significant advantages when making a layer using a single patterned beam, and results in improved speed and accuracy. To implement relatively low-cost projection stereolithography, we developed a system using a commercially available resin, which cures on exposure to visible light. The optimum photoinitiator was investigated, as well as the mixing ratio. The viscosity, shrinkage, curing depth and tensile strength were evaluated through several experiments on fabricated three-dimensional structures, and thus an optimal resin selection system was developed.