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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
A Study on Development of Torch Rotating Mechanism for Automation of Welding of Corrugated Membranes
Bae, Kang Yul ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 3, 2015, Pages 243~251
DOI : 10.7736/KSPE.2015.32.3.243
In order to develop an automatic system for welding thin steel plates with curvature such as the corrugated membranes of an LNG storage tank, a rotating mechanism should be firstly designed for the torch to easily follow the weld seam with a constant distance and angle. In this study, a torch rotating mechanism consisting of three circular links, two square-type links and a torch link was proposed for automation of the welding process. A weld-seam tracking system with two axis slides and the proposed rotating mechanism was successfully simulated with a dynamic simulation software. A prototype tracking system was manufactured and a tracking test with the system was then carried out. The test results with tracking system showed that the rotating mechanism could be implemented and it was feasible to be used in automatic tracking of weld seam with curvature.
Geometric Singularity Avoidance of a 3-SPS/S Parallel Mechanism with Redundancy using Conformal Geometric Algebra
Kim, Je Seok ; Jeong, Jin Han ; Park, Jahng Hyon ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 3, 2015, Pages 253~261
DOI : 10.7736/KSPE.2015.32.3.253
A parallel mechanism with redundancy can be regarded as a means for not only maximizing the benefits of parallel mechanisms but also overcoming their drawbacks. We proposed a novel parallel mechanism by eliminating an unnecessary degree of freedom of the configuration space. Because of redundancy, however, the solution for the inverse kinematics of the developed parallel mechanism is infinite. Therefore, we defined a cost function that can minimize the movement time to the target orientation and found the solution for the inverse kinematics by using a numerical method. In addition, we proposed a method for determining the boundary of the geometric singularity in order to avoid singularities.
Lost Motion Analysis for Nonlinearity Identification of a 6-DOF Ultra-Precision Positioning Stage
Shin, Hyun-Pyo ; Moon, Jun-Hee ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 3, 2015, Pages 263~268
DOI : 10.7736/KSPE.2015.32.3.263
This paper describes lost motion analysis for a novel 6-DOF ultra-precision positioning stage. In the case of flexure hinge based precision positioning stage, lost motion is generated when the displacement of actuator is not delivered completely to the end-effector because of the elasticity of flexure hinge. Consequently, it is need to compute amount of lost motion to compensate the motion or to decide appropriate control method for precision positioning. Lost motion analysis for the vertical actuation unit is presented. The analysis results are presented in two ways: analytic and numerical analyses. It is found that they closely coincide with each other by 1% error. In finite element analysis result, the amount of lost motion is turned out to be about 3%. Although, the amount is not so large, it is necessary procedure to check the lost motion to establish the control method.
Optimal Design for CNG Composite Pressure Vessel Using Basalt Fiber
Jang, Hyo Seong ; Bae, Jun Ho ; Kim, Chul ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 3, 2015, Pages 269~277
DOI : 10.7736/KSPE.2015.32.3.269
Compressed natural gas (CNG) composite vessels for vehicles have been generally made of 34CrMo4 for a inner liner part and E-glass/epoxy for a composite layer part. But, there is a problem of material loss of CNG composite vessels used in vehicles due to the design of excessive thickness of the liner. And, light weight of the CNG composite vessel is required for improving fuel efficiency. In this study, optimal design for CNG composite pressure vessel was performed by using basalt fiber, which is the environment-friendly material having a good mechanical strength. The optimal thickness of each part (inner liner and composite layer) was determined by theoretical analysis and FEA for satisfying structural safety and lightweight of the vessel. Also, for improving fatigue life, optimal autofrettage pressure was derived from FEA results.
Development of Electric Motion Wheel Chair Driving System using Planetary Gear Device
Youm, Kwang Wook ; Ham, Seong Hun ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 3, 2015, Pages 279~284
DOI : 10.7736/KSPE.2015.32.3.279
A wheelchair until now, decelerators using belt, chain and worm gears, etc have been widely used. However, a decelerator takes a large space although it is a simple device and thus is not ideal for the driving part of manual/motorized wheelchair. For these reasons, in this study we developed a driving part producing a large driving force through a decelerator using planetary gears. worm gear-based decelerator. We designed the tooth profile of the planetary gears for decelerator using Kisssoft program, In addition, we designed the driving part so as to apply it to the wheels of conventional wheelchairs, and then optimized the mechanism for the principles of manual/motorized transposition of the driving part and the operational principles. Based on the results of this study, we finally designed and manufactured a driving part for wheelchair decelerator in the form of planetary gears with 1 sun gear, 2 planetary gears and 1 ring gear.
Wireless Wearable GRF Sensing System for Continuous Measurements
Lee, Dongkwan ; Jeong, Yongrok ; Gu, Gwang Min ; Kim, Jung ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 3, 2015, Pages 285~292
DOI : 10.7736/KSPE.2015.32.3.285
This paper presents a wireless ground reaction force (GRF) sensing system for ambulatory GRF recording. The system is largely divided into three parts: force sensing modules based on optical sensor, outsole type frame, and embedded system for wireless communication. The force sensing module has advantages of the low height, robustness to the moment interference, and stable response in long term use. In simulation study, the strain and stress properties were examined to satisfy the requirements of the GRF sensing system. Four sensing modules were mounted on the toe, ball, and heel of foot shaped frame, respectively. The GRF signals were extracted using Micrpcontroller unit and transferred to the smart phone via Bluetooth communication. We measured the GRF during the normal walking for the validation of the continuous recording capability. The recorded GRF was comparable to the off the shelf stationary force plate.
Fabrication and Characterization of Polymer Microlens using Solvent-vapor-assisted Reflow
Yang, Seung Woo ; Kim, Sin Hyeong ; Kim, Bo Hyun ; Cho, Young Hak ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 3, 2015, Pages 299~305
DOI : 10.7736/KSPE.2015.32.3.299
In this paper, we propose a simple and low-cost fabrication method of polymer microlens using solvent-vapor-assisted reflow (SVAR). Metal molds for replication of polymer were fabricated using micro milling and the cylindrical shape of polymer was imprinted using hot-embossing process. The cylindrical shape of polymer was changed to hemispherical lens shape by SVAR. The characteristics of fabricated microlens were evaluated according to the condition of SVAR such as temperature and time. The focal length of polymer microlens could be controlled more easily in low-temperature and long-time condition than in high-temperature and short-time condition. That is, the level of concentrated light to focal point could be improved through the control of temperature and time. Also, we confirmed that toluene was more appropriate solvent than acetone in fabrication of PMMA polymer microlens using SVAR.
Development of Liquid Metal Strain Gauge for Measuring WT Blade`s Deformation
Park, In Kyum ; Seo, Youngho ; Kim, Byeong Hee ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 3, 2015, Pages 307~314
DOI : 10.7736/KSPE.2015.32.3.307
In this paper, the embedding type novel liquid metal strain gauge was developed for measuring the deformation of wind turbine blades. In general, the conventional methods for the SHM have many disadvantages such as frequency distortion in FBG sensors, the low gauge factor and mechanical failures in strain gauges and extremely sophisticated filtering in AE sensors. However, the liquid metal filled in a pre-confined micro channel shows dramatic characteristics such as high sensitivity, flexibility and robustnes! s to environment. To adopt such a high feasibility of the liquid metal in flexible sensor applications, the EGaIn was introduced to make flexible liquid metal strain gauges for the SHM. A micro channeled flexible film fabricated by the several MEMS processes and the PDMS replication was filled with EGaIn and wire-connected. Lots of experiments were conducted to investigate the performance of the developed strain gauges and verify the feasibility to the actual wind turbine blades health monitoring.