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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of The Korean Society of Manufacturing Technology Engineers
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Journal DOI :
The Korean Society of Manufacturing Technology Engineers
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Volume & Issues
Volume 24, Issue 6 - Dec 2015
Volume 24, Issue 5 - Oct 2015
Volume 24, Issue 4 - Aug 2015
Volume 24, Issue 3 - Jun 2015
Volume 24, Issue 2 - Apr 2015
Volume 24, Issue 1 - Feb 2015
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Evaluation of Elastic Properties for Nanoscale Coating Layers Using Ultrasonic Atomic Force Microscopy
Kwak, Dong Ryul ; Cho, Seung Bum ; Park, Ik Keun ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 24, issue 5, 2015, Pages 475~480
DOI : 10.7735/ksmte.2015.24.5.475
Ultrasonic atomic force microscopy (Ultrasonic-AFM) has been used to investigate the elastic property of the ultra-thin coating layer in a thin-film system. The modified Hertzian theory was applied to predict the contact resonance frequency through accurate theoretical analysis of the dynamic characteristics of the cantilever. We coat 200 nm thick Aluminum and Titanium thin films on the substrate using the DC Magnetron sputtering method. The amplitude and phase of the contact resonance frequency of a vibrating cantilever varies in response to the local stiffness constant. Ultrasonic-AFM images were obtained using the variations in the elastic property of the materials. The morphology of the surface was clearly observed in the Ultrasonic-AFM images, but was barely visible in the topography. This research demonstrates that Ultrasonic-AFM is a promising technique for visualizing the distribution of local stiffness in the nano-scale thin coatings.
Acoustic Characteristics of High Intensity Focused Ultrasound for Necrosis of CTO
Park, Chan Hee ; Jeong, Sang Hwa ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 24, issue 5, 2015, Pages 481~488
DOI : 10.7735/ksmte.2015.24.5.481
It is difficult to see a therapeutic effect from cardiovascular disease treatment methods in the case of a hardened chronic total occlusion (CTO), owing to the calcification of the deposition materials. However, lesion cells, such as CTOs, can be selectively necrotized without affecting the normal tissue using high-intensity ultrasound focused on one point. In this study, a phantom CTO was necrotized by a high-intensity focused ultrasound (HIFU) energy system, and the acoustic characteristics in the focal region were analyzed. An experimental HIFU device was constructed to discover the appropriate conditions for the necrosis of a phantom CTO. The transfer characteristics of the ultrasound changed in the focal region by the density difference of the phantom CTO. These changes were acoustically analyzed to choose the available frequency band for each density. On-off temperature control in the focal region was applied to prevent rapid temperature rises, which would otherwise affect normal tissue.
Integration Forming Technology based on Cold Hot Forging of Clutch Jaw Parts for Farm Machinery
Park, Dong-Hwan ; Han, Seong-Chul ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 24, issue 5, 2015, Pages 489~495
DOI : 10.7735/ksmte.2015.24.5.489
Forging is a manufacturing process involving the shaping of metal using localized compressive forces and the process of deforming metal into a predetermined shape using certain tools and press according to the temperature. Forging provides stronger metal parts than that possible by casting or machining. Conventional clutch jaw parts have been developed through cold forging and precision machining; however, fabrication of integral clutch jaw parts for farm machinery has not been reported yet. These parts were developed by applying a complex forging technology combining cold and hot forging. The integrated forming technology proposed in this study will be useful for reducing the lead-time for manufacturing, improving the accuracy of products, and eliminating the welding process.
Calibration Methods for Measurement Uncertainty of Power Assembly Tools
Oh, Se-heon ; Kang, Ki-young ; Hong, Min-sung ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 24, issue 5, 2015, Pages 496~501
DOI : 10.7735/ksmte.2015.24.5.496
In this study, calibration procedure of power assembly tools is suggested and methods are developed for calculating measurement uncertainty. Fist of all, the calibration of joint simulator bench (JSB) was carried out for maintaining traceability and the uncertainty components of JSB were analyzed. The influences of tool speed, tolerance, temperature and length of the adapter were examined by the torque measurement values through experiments. From this research, credibility for calibration results could be enhanced. This experimental results, being used as an effective tool for calibration of power assembly tools, will provide and improve the accuracy of the use of the power assembly tools.
Characterization of Microscale Drilling Process for Functionally Graded M2-Cu Material Using Design of Experiments
Sim, Jongwoo ; Choi, Dae Cheol ; Shin, Ki-Hoon ; Kim, Hong Seok ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 24, issue 5, 2015, Pages 502~507
DOI : 10.7735/ksmte.2015.24.5.502
In this study, a microscale drilling process was conducted to evaluate the cutting characteristics of functionally graded materials. A mixture of M2 and Cu powders were formed and sintered to produce disk specimens of various compositions. Subsequently, a microscale hole was created in the specimen by using a desktop-size micro-machining system. By using design of experiments and analysis of variance, it was found that the M2-Cu composition, spindle speed, and the interactions between these two factors had significant effects on the magnitude of cutting forces. However, the influence of feed rate on the cutting force was negligible. A mathematical model was established to predict the cutting force under a wide range of process conditions, and the reliability of the model was confirmed experimentally. In addition, it was observed that increasing the wt% of Cu in an M2-Cu specimen increased the high-frequency amplitude of cutting forces.
Analysis on the Effects of Tool Rake Angle and Helix Angle of a Flat End-mill in the Milling of Ti-alloy
Ye, Dong-Hee ; Koo, Joon-Young ; Park, Young-Koon ; Kim, Jeong-Suk ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 24, issue 5, 2015, Pages 508~513
DOI : 10.7735/ksmte.2015.24.5.508
In this study, the effect of the helix angle and rake angle of a flat end-mill in the milling of titanium alloy was investigated. Tool shape parameters such as helix angle and rake angle affect the cutting force, cutting zone temperature, vibration, and chip flow mechanism, which in turn determine tool life, surface integrity, and dimensional accuracy of the milling process. To investigate the effect of the helix and rake angles, a certain range of parameters was selected, and three-dimensional tool models were generated for finite element analysis (FEA) for each case. The cutting force and pressure on the tool flank face and rake face were investigated by FEA. Further, several tool models were proposed for machining tests. The cutting force characteristics were investigated by the machining tests.
The Influence of Suspension Stiffness on the Gearbox Input Loads in a 3-Point Suspension Wind Turbine Drive Train
Nam, Ju Seok ; Nam, Yong Yun ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 24, issue 5, 2015, Pages 514~520
DOI : 10.7735/ksmte.2015.24.5.514
The effects of suspension stiffness on the reaction load of the gearbox suspension for a three-point suspension wind turbine drive train were investigated by finite element analysis. The reaction forces of the gearbox suspension appear to increase as the gearbox suspension stiffness increases; however, the main bearing stiffness has a reverse effect on the reaction forces. The influence of the gearbox suspension stiffness is greater than that of the main bearing. Since the suspensions must provide the gearbox with proper support, it is not practical to use soft gearbox suspension for small reaction forces. It is more feasible to use stiff main bearings. As a guideline for the main bearing stiffness in the present study, we propose a relative stiffness of 100-150% of the reference.
Reliability Assessment Criteria of Motorized Roller Conveyor
Kim, Young-Joo ; Go, Hee-Yang ; Han, In-Sup ; Kim, Yong Soo ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 24, issue 5, 2015, Pages 521~529
DOI : 10.7735/ksmte.2015.24.5.521
Owing to a reliance on imported products from Europe and Japan, the use of logistics equipment with poor energy efficiency coupled with high maintenance costs can lead to high operating costs for some domestic logistic centers. To lower their operating costs, the logistic centers use motorized roller conveyors. In order to commercialize this process, it is necessary to establish the test criteria and assess the reliability of the process. Currently, there exists no standard verification method to test the reliability of motorized roller conveyors. In this study, we propose reliability assessment criteria for a: i) reliability test, ii) environmental test, iii) safety test, and iv) lifetime test.
Development of 20-kHz Ultrasonic Equipment for UNSM
Shin, Hyun-Geun ; Kim, Hyunse ; Lim, Euisu ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 24, issue 5, 2015, Pages 530~534
DOI : 10.7735/ksmte.2015.24.5.530
Ultrasonic nanocrystal surface modification (UNSM) is an example of a nanoscale-surface modification that has become noticeable because of its effects on the mechanical improvement of metallic materials. UNSM equipment needs to be both utilized and improved. The equipment is based on an ultrasonic waveguide whose role is to strike surfaces of metallic materials to achieve nanoscale deformation. In this paper, we introduce the development of one kind of UNSM equipment. Using piezoelectric elements, we repeatedly design and fabricate a 20-kHz ultrasonic waveguide. With respect to the composition of the equipment, the waveguide is automatically transferred by two axial stages automatically. In addition, a static force is constantly applied by pneumatic devices. We perform an experiment to verify the feasibility of the equipment.
Thermal Stress Calculations Using Enhanced Green's Function Considering Temperature-dependent Material Properties
Han, Tae-Song ; Huh, Nam-Su ; Jeon, Hyun-Ik ; Ha, Seung-Woo ; Cho, Sun-Young ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 24, issue 5, 2015, Pages 535~540
DOI : 10.7735/ksmte.2015.24.5.535
We propose an enhanced Green's function approach to predict thermal stresses by considering temperature-dependent material properties. We introduce three correction factors for the maximum stress, the time taken to reach maximum stress, and the time required to attain steady state based on the Green's function results for each temperature. The proposed approach considers temperature-dependent material properties using correction factors, which are defined as polynomial expressions with respect to temperatures based on Green's functions, that we obtain from finite-element (FE) analyses at each temperature. We verify the proposed approach by performing detailed FE analyses on thermal transients. The Green's functions predicted by the proposed approach are in good agreement with those obtained from FE analyses for all temperatures. Moreover, the thermal stresses predicted using the proposed approach are also in good agreement with the FE results, and the proposed approach provides better predictions than the conventional Green's function approach using constant, time-independent material properties.
Driving Performance Prediction for Low-floor Midsize bus Using Simulator
Kim, Gisu ; Kim, Jinseong ; Park, Yeong-il ; Lee, Chibum ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 24, issue 5, 2015, Pages 541~547
DOI : 10.7735/ksmte.2015.24.5.541
In this study, the performance of a low-floor midsize bus under development is predicted through simulations. To predict the vehicle's acceleration, maximum speed, and uphill driving performance, a forward simulator which calculates the vehicle power is developed. Also we verify the forward simulator by comparing simulations and test result for benchmarking vehicle. To predict the fuel consumption, we use a backward simulator for a specified road cycle. However, to predict the fuel consumption using the backward simulation the engine fuel-consumption map is needed. The engine fuel-consumption map extracting data from a similar sized diesel engine is used by re-scaling the maximum torque. As a result, we simulate the vehicle's forward performance with a new engine. Further, we simulated the backward performance to optimize the fuel efficiency and gearshift timing.
Quadruped Walking Control of DRC-HUBO
Kim, Jung-Yup ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 24, issue 5, 2015, Pages 548~552
DOI : 10.7735/ksmte.2015.24.5.548
In this paper, we describe the quadruped walking-control algorithm of the complete full-size humanoid DARPA Robotics Challenge-HUBO (DRC-HUBO) robot. Although DRC-HUBO is a biped robot, we require a quadruped walking function using two legs and two arms to overcome uneven terrains in the DRC. We design a wave-type quadruped walking pattern as a feedforward control using several walking parameters, and we design zero moment point (ZMP) controllers to maintain stable walking using an inverted pendulum model and an observed-state feedback control scheme. In particular, we propose a switching algorithm for ZMP controllers using supporting value and weighting factors in order to maintain the ZMP control performance during foot switching. Finally, we verify the proposed algorithm by performing quadruped walking experiments using DRC-HUBO.
Closed-Form Solutions for Stress Intensity Factor and Elastic Crack Opening Displacement for Circumferential Through-Wall Cracks in the Interface between an Elbow and a Straight Pipe under Internal Pressure
Jang, Youn-Young ; Jeong, Jae-Uk ; Huh, Nam-Su ; Kim, Ki-Seok ; Cho, Woo-Yeon ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 24, issue 5, 2015, Pages 553~560
DOI : 10.7735/ksmte.2015.24.5.553
Fracture mechanics analysis for cracked pipes is essential for applying the leak-before-break (LBB) concept to nuclear piping design. For LBB assessment, crack instability and leak rate should be predicted accurately for through-wall cracked pipes. In a nuclear piping system, elbows are connected with straight pipes by circumferential welding; this weld region is often considered a critical location. Hence, accurate crack assessment is necessary for cracks in the interface between elbows and straight pipes. In this study, the stress intensity factor (SIF) and elastic crack opening displacement (COD) were estimated through detailed 3D elastic finite element (FE) analyses. Based on the results, closed-form solutions of shape factors for calculating the SIFs and elastic CODs were proposed for circumferential through-wall cracks in the abovementioned interfaces under internal pressure. In addition, the effect of the elbow on shape factors was investigated by comparing the results with the existing solutions for a straight pipe.
Design and Manufacture of Therapeutic Dolls for Pulse Measurement of Elderly Patients with Dementia
Cha, Chiyoung ; Won, Seungmook ; Lee, JinKyu ; Kim, Seong Keol ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 24, issue 5, 2015, Pages 561~567
DOI : 10.7735/ksmte.2015.24.5.561
For a long time, therapeutic dolls have been provided to elderly patients with dementia as a non-drug therapy in several western countries. These dolls are made to resemble newborn babies. Touching the dolls and singing lullabies remind the elderly of taking care of their babies. These actions are effective in decreasing anxiety and reducing aggression, particularly, in the elderly with dementia. These dolls also help them to adapt to new places such as nursing facilities. This work proposes the installation of advanced systems in therapeutic dolls to aid the medical treatment of dementia patients by stabilizing their physical and mental health.
Design and Manufacture of a Hand-made Vehicle Based on a Formula
Lee, Soo Jin ; Jeong, Wonsun ; Kim, Geunbi ; Kim, Seong Keol ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 24, issue 5, 2015, Pages 568~575
DOI : 10.7735/ksmte.2015.24.5.568
A hand-made vehicle with a formula (VF-1) was designed and manufactured with the aim of realizing a lightweight and high-performance vehicle. The driver's body weight and stiffness of the frame were considered. The vehicle was equipped with a one-cylinder Exiv 250 engine with intake manifold potting for realizing weight reduction, high performance, and low cost. The suspension system for the formula was designed through the analyses and tests of vehicle motion and equipment. In a steering system, anti-Ackerman geometry was introduced to increase the transverse force during cornering. A full electric paddle shift system was adopted to decrease the braking distance. For protection against the distortion and warping of the frame, tungsten inert gas (TIG) welding technology was used.
Component Sizing for the Hybrid Electric Vehicle (HEV) of Our Own Making Using Dynamic Programming
Kim, Gisu ; Kim, Jinseong ; Park, Yeong-il ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 24, issue 5, 2015, Pages 576~582
DOI : 10.7735/ksmte.2015.24.5.576
Generally, the fuel economy of hybrid electric vehicle (HEV) is effected by the size of each component. In this study the fuel economy for HEV of our own making is evaluated using backward simulator, where dynamic programming is applied. In a competition, the vehicle is running through the road course that includes many speed bumps and steep grade. Therefore, the new driving cycle including road grade is developed for the simulation. The backward simulator is also developed through modeling each component. A performance map of engine and motor for component sizing is made from the existing engine map and motor map adapted to the HEV of our own making. For optimal component sizing, the feasible region is defined by restricting the power range of power sources. Optimal component size for best fuel economy is obtained within the feasible region through the backward simulation.
Development of a Half-Duplex Communication Device for Use via Human Skin
Kim, Won-Jun ; Song, Kyo-Yong ; Kim, Young-Pil ; Ko, Dong-Young ; Kim, Jung-Han ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 24, issue 5, 2015, Pages 583~587
DOI : 10.7735/ksmte.2015.24.5.583
In this study, a half-duplex mutual communication device via human skin was developed. Frequency-shift keying (FSK) digital modulation and demodulation control were used to transmit and receive data. Data communication through the human body is an effective communication technique and has high-grade security characteristics. In addition, making contact is a natural instinct of humans. Transmitting data through the human body is currently a highly conspicuous technology, because recently a lot of commercial sensors for humans have been developed. A body area network (BAN) can be easily constructed by this communication method on human skin. In this study, a half-duplex FSK mutual communication device was developed using a commercial FSK modulator and demodulator. A special control switching circuit and communication sequence were developed for mutual communication through human skin.