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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 26, Issue 12 - Dec 2009
Volume 26, Issue 11 - Nov 2009
Volume 26, Issue 10 - Oct 2009
Volume 26, Issue 9 - Sep 2009
Volume 26, Issue 8 - Aug 2009
Volume 26, Issue 7 - Jul 2009
Volume 26, Issue 6 - Jun 2009
Volume 26, Issue 5 - May 2009
Volume 26, Issue 4 - Apr 2009
Volume 26, Issue 3 - Mar 2009
Volume 26, Issue 2 - Feb 2009
Volume 26, Issue 1 - Jan 2009
Selecting the target year
Thermal Fatigue Test Methods for Thermal Barrier Coatings of Gas Turbine Blade
Kim, Dae-Jin ; Koo, Jae-Mean ; Seok, Chang-Sung ; Won, Jong-Il ; Park, Sang-Yeol ; Kim, Mun-Young ; Lee, Sung-Ho ;
Journal of the Korean Society for Precision Engineering, volume 26, issue 2, 2009, Pages 7~15
Solidification Microstructure and Carbide Formation in the Co Base Superalloy
Lee, Hyun-Jung ; Lee, Je-Hyun ; Seo, Seong-Moon ; Jo, Chang-Young ; Lee, Sung-Ho ; Kim, Moon-Young ;
Journal of the Korean Society for Precision Engineering, volume 26, issue 2, 2009, Pages 16~20
Design of Zirconia-based material for Thermal Barrier Coating
Heo, Yong-Suk ; Lee, Dae-Hyung ; Jung, Yeon-Gil ; Paik, Un-Kyu ; Lee, Kee-Sung ;
Journal of the Korean Society for Precision Engineering, volume 26, issue 2, 2009, Pages 21~25
A Study on Machinability and Cost Evaluation of MQL Milling Process
Lee, Ji-Hyung ; Ko, Tae-Jo ; Baek, Dae-Gyun ;
Journal of the Korean Society for Precision Engineering, volume 26, issue 2, 2009, Pages 26~34
This paper is related to MQL (Minimum Quantity Lubrication) milling process, which is one of the environmentally friendly cuttings. The objective is to compare MQL milling process with conventional cutting fluid systems. To this end, machinability of MQL milling process was investigated, followed by the cost evaluation. Cutting force, surface roughness, tool wear, and cutting temperature were compared with each cutting fluid method. Consequently, total production costs wear evaluated with the mathematical models in terms of machining cost and cutting fluid loss.
Design and Testing of a Long Stroke Fast Tool Servo for Ultra-precision Free-form Machining
Kim, Ho-Sang ; Lee, Kwang-Il ;
Journal of the Korean Society for Precision Engineering, volume 26, issue 2, 2009, Pages 35~44
Long stroke Fast Tool Servo (LFTS) with maximum stroke of
is designed, manufactured and tested for fabrication of optical free-form surfaces. The large amount of stroke in LFTS has been realized by utilizing the hinge and lever mechanisms which enable the displacement amplification ratio of 4.3. In this mechanism the peculiar shape was devised for maximizing the displacement of end tip in LFTS and special mechanical spring has been mounted to provide the sufficient preload to the piezoelectric actuator. Also, its longitudinal motion of tool tip can be measured by capacitive type displacement sensor and closed-loop controlled to overcome the nonlinear hysteresis. In order to verify the static and dynamic characteristics of designed LFTS, several features including step response, frequency response and cut-off frequency in closed-loop mode were experimentally examined. Also, basic machining result shows that the proposed LFTS is capable of generating the optical free-form surface as an additional axis in diamond turning machine.
Active Force Control of Electro-Hydraulic Hybrid Load Simulator using Quantitative Feedback Theory
Yoon, Joo-Hyeon ; Ahn, Kyoung-Kwan ; Truong, Dinh Quang ; Jo, Woo-Geun ;
Journal of the Korean Society for Precision Engineering, volume 26, issue 2, 2009, Pages 45~53
Today, reduction of
exhaustion gas for global-warming prevention becomes important issues in all industrial fields. Hydraulic systems have been widely used in industrial applications due to high power density and so on. However hydraulic pump is always being operated by engine or electric motor in the conventional hydraulic system. Therefore most of the conventional hydraulic system is not efficient system. Recently, an electro-hydraulic hybrid system, which combines electric and hydraulic technology in a compact unit, can be adapted to a wide variety of force, speed and torque requirements. In the electro-hydraulic hybrid system, hydraulic pump is operated by electric motor only when hydraulic power is needed. Therefore the electro-hydraulic system can reduce the energy consumption drastically when compared to the conventional hydraulic systems. This paper presents a new kind of hydraulic load simulator which is composed of electro-hydraulic hybrid system. Disturbances in the real working condition make the control performance decrease or go bad. QFT controller is designed to eliminate or reduce the disturbance and improve the control performance of the electro-hydraulic load simulator. Experimental results show that the proposed controller is verified to apply for electro-hydraulic hybrid system with varied external disturbances.
A Study on the Piezo Injector Control Algorithm for CRDI Diesel Engines
Oh, Byoung-Gul ; Oh, Seung-Suk ; Park, Yeong-Seop ; Lee, Kang-Yoon ; SunWoo, Myoung-Ho ;
Journal of the Korean Society for Precision Engineering, volume 26, issue 2, 2009, Pages 54~62
The purpose of this study is to develop a piezo injector driver for common-rail direct injection diesel engines. In this research, we analyzed the electrical and mechanical characteristics of the piezo actuator through experiments. Current flow and charging voltage of the piezo injector are controlled by the PWM signal of variable duty ratio in order to realize both fast response and low peak current. The optimal switching duty ratio was designed by modeling and analyzing of the piezo driver circuit. In order to avoid resonance and unacceptably long settling time, appropriate frequency range of the PWM signal was derived based on the driver circuit model. The developed injector driver was validated by experiments under various fuel rail pressure, injection duration, and charging voltage.
Path Planning of a Mobile Robot Using RF Strength in Sensor Networks
Wee, Sung-Gil ; Kim, Yoon-Gu ; Lee, Ki-Dong ; Choi, Jung-Won ; Park, Ju-Hyun ; Lee, Suk-Gyu ;
Journal of the Korean Society for Precision Engineering, volume 26, issue 2, 2009, Pages 63~70
This paper proposes a novel path finding approach of a mobile robot using RF strength in sensor network. In the experiments based on the proposed method, a mobile robot attempts to find its location, heading direction and the shortest path in the indoor environment. The experimental system consisting of mesh network shares node data and send them to base station. The triangulation and the proposed Grid method calculate the location and heading angle of the robot. In addition, the robot finds the shortest path by using the base station attached on it to receive data of environment around each node. Kalman filter reduces the straight line error when the robot estimates the strength of received signal. The experimental results show the effectiveness of the proposed algorithm.
A Study on The Curvature Extrusion for Automotive Aluminum Suspension Arm
Lee, Sang-Kon ; Kim, Byung-Min ; Oh, Kae-Hee ;
Journal of the Korean Society for Precision Engineering, volume 26, issue 2, 2009, Pages 71~77
In the automotive industry, aluminum is widely used to reduce the vehicle weight. Aluminum curved extruded components are used for the design of frame parts. This study investigates the curvature extrusion process to produce the aluminum curved suspension arm. In the curvature extrusion process, the bending process is simultaneously carried out with the extrusion process. Firstly, porthole extrusion was investigated by using FE analysis to produce aluminum suspension arm. And then the bending process condition was determined to produce the final suspension arm with the required curvature. In this research, the guide roll movement causes the bending of extruded product. The moving distance and velocity of guide roll were controlled to meet the required curvature of suspension arm. Finally, the curved suspension arm was manufactured by the curvature extrusion experiment under the proposed curvature extrusion condition.
Microwave Melting of the Basalt Rock and Fiber Spinning
Huh, You ; Kim, Hyung-Jin ; Yang, Hee-Won ; Jeon, Kyung-Jin ;
Journal of the Korean Society for Precision Engineering, volume 26, issue 2, 2009, Pages 78~85
High performance functional fibers are demanded increasingly in the modern industries, while the inorganic fibers such as carbon fibers, glass fibers, and metal fibers are representative among them in that they have high strength, consistent properties in a broad temperature change, etc.. This paper reports on the experimental trial to apply the microwave furnace on melting the natural basalt rock that spreads overall on the global surface and is supposed to be used as the raw material for the inorganic high performance fiber. Results showed that the new method to use the microwave as the heating source to melt the basalt rock was feasible. The crucible spinning could effectively applied for producing the basalt fibers up to 10 micrometer diameter, when the crushed basalt rocks were used. For drawing the molten basalt the drawing roller surface feature was a very important factor.
An evaluation on sealing performance of elastomeric O-ring compressed and highly pressurized
Park, Sung-Han ; Kim, Jae-Hoon ; Kim, Won-Hoon ;
Journal of the Korean Society for Precision Engineering, volume 26, issue 2, 2009, Pages 86~93
Elastomeric O-rings have been the most common seals due to their excellent sealing capacity, and availability in costs and sizes. One of the critical applications of O-ring seals is solid rocket motor joint seal where the operating hot gas must be sealed during the combustion. This has long been a design issue to avoid the system failure. For laterally constrained, squeezed and pressurized condition, deformed shape of O-ring was measured by computed tomography method and CCD laser sensor, compared with numerical calculations. As clearance gap changes, sealing performance had been evaluated on peak contact stresses at top, bottom and side contact surfaces. As clearance gap increases, peak contact stresses and contact widths in top and side contact surfaces increase, and the asymmetry of stress distributions is promoted due to pressure increase. It is suggested that peak stress of bottom contact surface can be approximated by simple superposition of peak ones due to squeeze and pressure. Under pressurized condition, sealing performance is dependent on not peak stresses of bottom and side contact surfaces but that of top.
A Study of Structural Analysis and Torsional Characteristic of the Sleeve Spring Type-Torsional Vibration Damper
Hwang, Beom-Cheol ; Kim, Chul ; Bae, Won-Byoung ;
Journal of the Korean Society for Precision Engineering, volume 26, issue 2, 2009, Pages 94~100
In diesel engines, it is inevitable that the torsional vibration is produced by the fluctuation of engine torque. Therefore, it is necessary to establish preventive measures to diminish the torsional vibration. The sleeve spring type damper is one of the preventive measures for reducing the torsional vibration. In this study, a closed form equation to predict spring constant of the sleeve spring and torsional characteristic of the torsional vibration damper was proposed to calculate stiffness of the damper and verified their availability through the finite element analysis. The theoretical values have a good agreement with the results obtained by the finite element analysis. The results obtained from the equation derived enable the designers in actual fields to be more efficient.
Fretting Wear Test of Inconel 690 Tubes Employing Piezoelectric Actuator
Chung, Il-Sup ; Lee, Myung-Ho ; Park, Ki-Hong ; Lee, Jung-Hoon ; Kwon, Jae-Do ;
Journal of the Korean Society for Precision Engineering, volume 26, issue 2, 2009, Pages 101~108
A fretting wear test rig for dry ambient condition, which employs a piezoelectric actuator, has been developed. It is driven and loaded in a very simple manner with acceptable experimental accuracy. By using the rig, Inconel 690 tube has been tested under the normal load of 10 and 15N with sliding amplitude of less than
cycles. The wear resistance of the material has been characterized in terms of the wear coefficient based on the work rate model. SEM micrographs show the complex structures of the scars, which consist of risen peaks, plate-type thin layers and locally exposed bare surfaces. The cracks spread over the layers give clue to the fretting wear mechanism of the material.
Measurement and Active Compensation for 3-DOF Motion Errors of an Air Bearing Stage with Magnetic Preloads
Ro, Seung-Kook ; Kim, Soo-Hyun ; Kwak, Yoon-Keun ; Park, Chun-Hong ;
Journal of the Korean Society for Precision Engineering, volume 26, issue 2, 2009, Pages 109~117
This paper presents a linear air bearing stage with compensated motion errors by active control of preloads generated by magnetic actuators with combination of permanent and electromagnets. A 1-axis linear stage motorized with a linear motor with 240mm of travel range is built for verifying this design concept and tested its performances. The three motions of the table are controlled with four magnetic actuators driven by current amplifiers and a DSP based digital controller. Three motion errors were measured combined method with laser interferometer and two-probe method with
of repeatability for straightness error. The measured motion errors were modeled as functions of the stage position, and compensation were carried out with feedforward control because the characteristics of the motion control with magnetic actuators are linear and independent for each degree-of-freedoms. As the results, the errors were reduced from
for the vertical motion, from 9.42 sec to 0.18 sec for the pitch motion and from 2.42 sec to 0.18 sec for roll motion.
Size Classification of Airborne Nanoparticles Using Electrically Tunable Virtual Impactor
Kwon, Soon-Myung ; Kim, Yong-Ho ; Park, Dong-Ho ; Hwang, Jung-Ho ; Kim, Yong-Jun ;
Journal of the Korean Society for Precision Engineering, volume 26, issue 2, 2009, Pages 118~125
This paper reports the size classification of nanoparticles as well as electrical tuning techniques for the cut-off diameter and collection efficiency. Classifying particles < 100 nm in diameter is quite a technical challenge using a virtual impactor with the cut-off diameter being determined geometrically. However, the proposed virtual impactor can classify particles <100 nm and tune the cut-off diameter by electrically accelerating the particles. The cut-off diameter of the proposed device was tuned from 15 to 50nm.
A Comparative Study of Gait Characteristics between Single Axis Foot and Energy Storing Foot for Sports in Trans-tibial Amputee
Chang, Yun-Hee ; Bae, Tae-Soo ; Kim, Shin-Ki ; Mun, Mu-Seong ;
Journal of the Korean Society for Precision Engineering, volume 26, issue 2, 2009, Pages 126~132
This study examined the differences in spatio-temporal parameters, joint angle, ground reaction force (GRF), and joint power according to the changes of gait speed for trans-tibial amputees to investigate the features of the energy-storing foot for sports. The subjects walked at normal speed and at fast speed, wearing a single-axis type foot (Korec) and an energy-storing foot for sports (Renegade) respectively. The results showed that Renegade yielded faster gait speed as well as more symmetric gait pattern, compared to Korec. However, as gait speed was increased, there was no significant difference in kinematics, ground reaction force, and joint power between two artificial foots. This was similar to the results from previous studies regarding the energy-storing foot, where the walking velocity and gait symmetry have been improved. Nevertheless, the result of this study differed from the previous ones which reported that joint angle, joint power, and GRF increased as the gait speed increased except spatio-temporal parameters.
Toolpath Generation for Three-axis Round-end Milling of Triangular Mesh Surfaces
Chung, Yun-Chan ;
Journal of the Korean Society for Precision Engineering, volume 26, issue 2, 2009, Pages 133~140
Presented in this paper is a method to generate round-endmill toolpaths for sculptured surfaces represented as a triangular mesh model. The proposed method is applicable in toolpath generation for ball-endmills and flat-endmills because the round-endmill is a generalized tool in three-axis NC (numerical control) milling. The method uses a wireframe model as the offset model that represents a cutter location surface. Since wireframe models are relatively simple and fast to calculate, the proposed method can process large models and keep high precision. Intersection points with the wireframe offset model and a tool guide plane are calculated, and intersection curves are constructed by tracing the intersection points. The final step of the method is extracting regular curves from the intersection curves including degenerate and self-intersected segments. The proposed method is implemented and tested, and a practical example is presented.
Solving a Path Assignment Problem using s-t Cuts
Kim, Tae-Jung ;
Journal of the Korean Society for Precision Engineering, volume 26, issue 2, 2009, Pages 141~147
We introduce a noble method to find a variation of the optimal path problem. The problem is to find the optimal decomposition of an original planar region such that the number of paths in the region is minimized. The paths are required to uniformly cover each subregion and the directions of the paths in each sub-region are required to be either entirely vertical or entirely horizontal. We show how we can transform the path problem into a graph s-t cut problem. We solve the transformed s-t cut problem using the Ford-Fulkerson method and show its performance. The approach can be used in zig-zag milling and layerd manufacturing.