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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers A
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Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 38, Issue 12 - Dec 2014
Volume 38, Issue 11 - Nov 2014
Volume 38, Issue 10 - Oct 2014
Volume 38, Issue 9 - Sep 2014
Volume 38, Issue 8 - Aug 2014
Volume 38, Issue 7 - Jul 2014
Volume 38, Issue 6 - Jun 2014
Volume 38, Issue 5 - May 2014
Volume 38, Issue 4 - Apr 2014
Volume 38, Issue 3 - Mar 2014
Volume 38, Issue 2 - Feb 2014
Volume 38, Issue 1 - Jan 2014
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Modeling of Capillary Filling Length in Silwet L-77 Added Poly(Dimethylsiloxane) (PDMS) Microchannels
Lee, Bom-Yee ; Lee, Bong-Kee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 8, 2014, Pages 823~829
DOI : 10.3795/KSME-A.2014.38.8.823
In the present study, simple models were proposed to predict the capillary-driven flow length in a surfactant-added poly(dimethylsiloxane) (PDMS) rectangular microchannel. Owing to the hydrophobic nature of PDMS, it is difficult to transport water in a conventional PDMS microchannel by means of the capillary force alone. To overcome this problem, microchannels with a hydrophilic surface were fabricated using surfactant-added PDMS. By measuring the contact angle change on the surfactant-added PDMS surface, the behavior was investigated to establish a simple model. In order to predict the filling length induced by the capillary force, the Washburn equation was modified in the present study. From the investigation, it was found that the initial rate-of-change of the contact angle affected the filling length. Simple models were developed for three representative cases, and these can be useful tools in designing microfluidic manufacturing techniques including MIcroMolding In Capillaries (MIMIC).
Evaluation of Creep-Fatigue Integrity for High Temperature Pressure Vessel in a Sodium Test Loop
Lee, Hyeong-Yeon ; Lee, Dong-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 8, 2014, Pages 831~836
DOI : 10.3795/KSME-A.2014.38.8.831
In this study, high temperature integrity evaluation on a pressure vessel of the expansion tank operating at elevated temperature of
in the sodium test facility of the SEFLA(Sodium Thermal-hydraulic Experiment Loop for Finned-tube Sodium-to-Air heat exchanger) to be constructed at KAERI has been performed. Evaluations of creep-fatigue damage based on a full 3D finite element analyses were conducted for the expansion tank according to the recent elevated temperature design codes of ASME Section III Subsection NH and French RCC-MRx. It was shown that the expansion tank maintains its integrity under the intended creep-fatigue loads. Quantitative code comparisons were conducted for the pressure vessel of austenitic stainless steel 316L.
Development of Intelligent Walking Assistive Robot Using Stereo Cameras
Park, Min-Jong ; Kim, Jung-Yup ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 8, 2014, Pages 837~848
DOI : 10.3795/KSME-A.2014.38.8.837
This paper describes the development of a walking assistive robot for effective self-rehabilitation for elderly people facing an inconvenience in walking. The main features of the developed robot are enhanced safety and mobility using the baby walker and electric wheelchair mechanisms and an accurate walking tracking control algorithm using potentiometers and stereo cameras. Specifically, a pelvis supporter is designed to prevent the user from falling down and reduce the burden on their legs, and electric motors are used for easy locomotion with low effort. Next, the walking intention and direction of the user are automatically recognized by using potentiometers attached at the pelvis supporter so that the robot can track the user, and the rapidity and accuracy of the tracking were increased by applying a lower-body motion analysis algorithm with stereo cameras. Finally, the user-tracking performance of the developed robot was experimentally verified through stepwise walking assistance experiments.
Manufacturing of GFRP Sheet Using Plain Weaving Method
Kim, in Woo ; Kim, Hyoung Seok ; Lee, Jung Hoon ; Lee, Dong Gi ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 8, 2014, Pages 849~855
DOI : 10.3795/KSME-A.2014.38.8.849
The GFRP composite is used for hot press flow molding of automotive components, and the different flow rates of fiber and plastic are likely to induce fiber orientation and inhomogeneity in the material. However, very limited systematic research studies are available on composite materials with superior flow homogeneity and optimized fiber orientation. The inhomogeneity and fiber orientation issues of GFRP composites have still not been resolved through research. The plain weaving method applied to the GFRP prepreg can improve its recyclability, inhomogeneity, fiber flow, structural stability, fiber deformation, surface smoothness, degree of impregnation, and other mechanical properties. The need for more detailed and thorough studies is evidenced.
Estimation of the Thickness and the Material Combination of the Thermal Stress Control Layer (TSCL) for the Stellite21 Hardfaced STD61 Hot Working Tool Steel Using Three-Dimensional Finite Element Analysis
Park, Na-Ra ; Ahn, Dong-Gyu ; Oh, Jin-Woo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 8, 2014, Pages 857~862
DOI : 10.3795/KSME-A.2014.38.8.857
The research on a thermal stress control layer (TSCL) begins to undertake to reduce residual stress and strain in the vicinity of the joined region between the hardfacing layer and the base part. The goal of this paper is to estimate the material combination and the thickness of TSCL for the Stellite21 hardfaced STD61 hot working tool steel via three-dimensional finite element analysis (FEA). TSCL is created by the combination of Stellite21 and STD61. The thickness of TSCL ranges from 0.5 mm to 1.5 mm. The influence of the material combination and the thickness of TSCL on temperature, thermal stress and thermal strain distributions of the hardfaced part have been investigated. The results of the investigation have been revealed that a proper material combination of TSCL is Stellite21 of 50 % and STD61 of 50 %, and its appropriate thickness is 1.0 mm.
Analysis of Acoustic Emission Signal Sensitivity to Variations in Thin-film Material Properties During CMP Process
Park, Sun Joon ; Lee, Hyun Seop ; Jeong, Hae Do ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 8, 2014, Pages 863~867
DOI : 10.3795/KSME-A.2014.38.8.863
In this study, an acoustic emission (AE) sensor was used for measuring the abrasive and molecular-scale phenomena in chemical mechanical polishing (CMP). An AE sensor is a transducer that converts a mechanical wave into an electrical signal, and is capable of acquiring high-level frequencies from materials. Therefore, an AE sensor was installed in the CMP equipment and the signals were measured simultaneously during the polishing process. In this study, an AE monitoring system was developed for investigating the sensitivity of the AE signal to (a) the variations in the material properties of the pad, slurry, and wafer and (b) the change in conditions during the CMP process. This system was adapted to Oxide and Cu CMP processes. AE signal parameters including AE raw frequency, FFT, and amplitude were analyzed for understanding the abrasive and molecular-level phenomena in the CMP process. Finally, we verified that AE sensors with different bandwidths could function in complementary ways during CMP process monitoring.
Development of Hybrid Fused Deposition Modeling System for Three-Dimensional Circuit Device Fabrication
O, Sung Taek ; Lee, In Hwan ; Kim, Ho-Chan ; Cho, Hae Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 8, 2014, Pages 869~874
DOI : 10.3795/KSME-A.2014.38.8.869
It is possible to fabricate a three-dimensional (3D) shape using the solid freeform fabrication (SFF) technology. However, there are several problems in applying conventional SFF technologies to the direct manufacturing of a product. Hence, multimaterial SFF is gaining attention. Moreover, a 3D circuit device that is different from a conventional two-dimensional PCB can also be fabricated using multimaterial SFF. In this study, a hybrid system using fused deposition modeling and direct writing was designed for 3D circuit device fabrication.
Fabrication and Evaluation of Hybrid Scaffold by Nano-Micro Precision Deposition System
Ha, Seong-Woo ; Kim, Jong Young ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 8, 2014, Pages 875~880
DOI : 10.3795/KSME-A.2014.38.8.875
Recently, three-dimensional scaffolds and nanofibers are being developed for bone tissue regeneration. In this study, we fabricated a hybrid scaffold using a nano-micro precision deposition system. The fabrication process involved the application of the solid freeform fabrication (SFF) technology and electrospinning. The hybrid scaffolds were combined using micro scaffolds and nanofibers. The nanofibers were deposited on each layer of the micro scaffolding using the electrospinning process. The micro scaffolds were fabricated using the SFF technology at a temperature of
, pressure of 650 kPa, and scan velocity of 250 mm/s. Nanofiber fabrication was conducted by means of electrospinning using the flow rate, solution concentration, distance from the tip to the collector (TCD), and voltage. The nanofibers were fabricated using a flow rate of 0.1 ml/min, voltage of 5 kV, TCD of 1 mm, and 10 wt% of solution concentration. MG-63 cells were seeded into the hybrid scaffold for the purpose of its evaluation.
Three Dimensional Layering Algorithm for 3-D Metal Printing Using 5-axis
Ryu, Sua ; Jee, Haeseong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 8, 2014, Pages 881~886
DOI : 10.3795/KSME-A.2014.38.8.881
The purpose of three-dimensional (3-D) metal printing using 5-axis is to deposit metal powder by changing the orientation of the deposited structure to be built for the overhang or undercut feature on part geometry. This requires a complicated preprocess functionality of providing three dimensionally sliced layers to cover the required part geometry. This study addresses the overhang/undercut problem in 3-D metal printing and discusses a possible solution of providing 3-D layers to be built using the DMT(R) machine.
Study on Abrasive Adhesion and Polishing Effect in Wet Magnetic Abrasive Polishing
Son, Chul-Bae ; Jin, Dong-Hyun ; Kwak, Jae-Seob ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 8, 2014, Pages 887~892
DOI : 10.3795/KSME-A.2014.38.8.887
In a conventional magnetic abrasive polishing process, the polishing abrasives are mixed with ferrous particles and slight cutting oil to form a cluster of abrasives. However, when a tool rotates at a high revolution speed, most of the polishing abrasives are scattered away from it due to the increase in centrifugal force. This phenomenon directly reduces the polishing efficiency. The use of a highly viscous matter such as silicone gel instead of cutting oil for mixing is one method to solve this problem and increase abrasive adhesion. Another method to avoid high abrasive scattering is the application of wet magnetic abrasive polishing (WMAP). In WMAP, abundant mineral oil is preliminarily applied to the workpiece surface. This study experimentally evaluated the effect of WMAP on abrasive adhesion. The relationship between the amount of working abrasives and polishing conditions was characterized. Despite the lower adhesion ratio of polishing abrasives, the surface roughness was found to be significantly improved as the result of WMAP.
Effects of Beam Pulse Width and Power Density in Silver Nanowire Welding Using Pulsed IR Laser
Kim, Joohan ; Yoon, Sang Woo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 8, 2014, Pages 893~898
DOI : 10.3795/KSME-A.2014.38.8.893
A direct pulsed laser process for welding and networking silver nanowires was developed. The welded nanowire network demonstrated modified electrical properties in a transparent substance. In particular, the welding points on the nanowires were investigated to measure the resistance at the connections. The level of networking in nanowires was explored with respect to various laser pulse widths and average power densities. In particular, the influence of laser beam density was investigated in detail. Selective laser treatment can be advantageous in imparting customized local property changes in transparent conducting materials. Various applications of the process are also discussed in this paper.
Study of Blank Thickness Optimization in Free Bulging for Maximizing Bulged Height
Yoo, Joon-Tae ; Yoon, Jong-Hoon ; Lee, Ho-Sung ; Youn, Sung-Kie ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 8, 2014, Pages 899~904
DOI : 10.3795/KSME-A.2014.38.8.899
Thickness profiled blank is designed using optimization techniques for maximizing the bulged heights during the free bulging of Inconel 718. The thickness of the blank was described by the Bezier curve and the locations of the control points were used as the design variables for optimization. The maximization of the bulged heights within the limited strain range served as the objective function and constraints for optimization. The equivalent static loads method for non-linear static response structural optimization (ESLSO) was used and the result of the optimization revealed 22 increased bulged heights. A free bulging test using a blank with an optimized profile was conducted to verify the optimization process. The results were compared with those of numerical analysis in terms of bulged height and deformed shape.
Optimization of Design Parameters for Steel Grating Using Taguchi Method Considering Rigidity and Drainage Efficiency
Kim, Woo-Tae ; Lee, Se-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 8, 2014, Pages 905~910
DOI : 10.3795/KSME-A.2014.38.8.905
The steel grating discussed in this study is a drain cover that enhances the rigidity of the steel frame using an inclined inflow tract for wastewater, facilitates smooth drainage, and prevents the escape of bad smell from the drain. Recently, the urban problem of bad smell in sewerage lines has been hindering the improvement of living standards. Moreover, the frequent failure of existing products deters bad smell prevention measures and results in administrative power and budget wastage. The pressure to reduce budgets propels the increased demand for functional steel grating. Thus, this study focused on optimizing the design parameters of a steel grating by simultaneously considering its rigidity and drainage efficiency.
Study of Shipbuilding Cost Estimation for Catamaran-type Leisure Boats Using Product Configuration Model
Oh, Dae Kyun ; Oh, Woo Jun ; Lee, Dong Kun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 8, 2014, Pages 911~916
DOI : 10.3795/KSME-A.2014.38.8.911
The leisure boat industry has the potential to become a high-value-added industry in the future. Recently, a study on Korean high-speed leisure boats for fishing was conducted. This study suggests a product configuration model-based shipbuilding cost estimation method for determining the type of leisure boat suitable for mass production, as part of a research for productivity improvement. The suggested estimation method based on the analysis of the leisure boat process and generic YWBS can calculate quantitative and concrete data. By using this method, the cost of building the catamaran-type design ship can be reduced by 17 times, compared to that of the monohull-type mother ship. This implies that the final design of the Korean high-speed leisure boat for fishing will have a competitive price at the actual production stage.
Prediction of Joining Torque for Bit Depth of Subminiature Bolt
Lee, Hyun-Kyu ; Park, Keun ; Ra, Seung-Woo ; Kim, Jong-Bong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 8, 2014, Pages 917~923
DOI : 10.3795/KSME-A.2014.38.8.917
Subminiature joining bolts are required for the electronic parts of gadgets such as mobile phones and watch phones. During the miniaturization of bolt heads, it is difficult to obtain sufficient joining force owing to the risk of shear fracture of the bolt head or severe plastic deformation on the bit region. In this study, the maximum joining torque for the bit depth was predicted using finite element analysis. A shear fracture test was conducted on a wire used in bolt forming. The results of this test were subjected to finite element analysis and a fracture criterion was obtained by comparing the experimental and analysis results. The shear fracture of the bolt head during joining was predicted based on the obtained criterion. Furthermore, the maximum joining torque was predicted for various bit depths. Fracture on the boundary between the bolt head and thread was found to occur in lower joining torque as bit depth increases.