Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korean Society for Precision Engineering
Journal Basic Information
Journal DOI :
Korean Society of Precision Engineering
Editor in Chief :
Volume & Issues
Volume 28, Issue 12 - Dec 2011
Volume 28, Issue 11 - Nov 2011
Volume 28, Issue 10 - Oct 2011
Volume 28, Issue 9 - Sep 2011
Volume 28, Issue 8 - Aug 2011
Volume 28, Issue 7 - Jul 2011
Volume 28, Issue 6 - Jun 2011
Volume 28, Issue 5 - May 2011
Volume 28, Issue 4 - Apr 2011
Volume 28, Issue 3 - Mar 2011
Volume 28, Issue 2 - Feb 2011
Volume 28, Issue 1 - Jan 2011
Selecting the target year
Analysis of Moving Heat Source for Laser Assisted Machining of Plate by Feed Rate Control
Kim, Kwang-Sun ; Lee, Choon-Man ;
Journal of the Korean Society for Precision Engineering, volume 28, issue 12, 2011, Pages 1341~1346
Currently, many researches are carried out for laser assisted machining, which is one of the important fields in materials difficult to process. However, a prediction of heat source is difficult because of moving heat source. In this paper, a thermal analysis of laser assisted machining of plate by change of heat source size is performed, and preheating temperature by adjusting the feed rate is controlled. It was recognized that the maximum preheating temperature increases according to the decrease in heat source size, and feed rate need to adjust as high speed. The results of this analysis can be used as a reference for preheating temperature prediction in laser assisted milling.
Analysis and Experiment of Ultrasonic Vibration Mechanism using PZT Actuator for Precision Laser Machining
Kim, Woo-Jin ; Jeon, Yong-Ho ; Cho, Sung-Hak ;
Journal of the Korean Society for Precision Engineering, volume 28, issue 12, 2011, Pages 1347~1352
Recently, as the aged population grows around the world, many medical instruments, devices, and their fabrication processes are developing. Among the devices, a drug delivery stent is a good example for precision machining. Conventional drug delivery stent has problem of the remaining polymer because the drug is coated on the surface with it. If the drug is impregnated into the micro hole array on the stent surface, the polymer can be perfectly eliminated. Micro sized holes are generally fabricated by laser machining however, the fabricated holes do not have an enough aspect ratio to contain the drug or a good surface finish to deliver the stend to blood vessel tissue. To overcome these problems, we propose a vibration-assisted machining mechanism with PZT (Piezoelectric Transducers) for abrication of micro sized holes better. The results indicated that the burr size can be significantly decreased with vibration assisted in nanosecond pulse laser drilling test.
Thermal Analysis for Laser Assisted Turning of Square Bar using Laser Heat Source Projection Method
Kim, Jae-Hyun ; Choi, Jun-Young ; Lee, Choon-Man ;
Journal of the Korean Society for Precision Engineering, volume 28, issue 12, 2011, Pages 1353~1358
LAT(Laser Assisted Turning) is a method that applies a machining process after softening a workpiece in which a preheating process is locally applied to its machining section using laser heat source. LAT shows several advantages, such as high productivity, reduction of manufacturing cost, high quality. Analysis of temperature distribution after preheating for LAT is very difficult due to its very small heat input area and large energy and its movement. Also, the LAT for a square bar is more difficult because the shape of a laser heat source can be changed according to the rotation of the workpiece. In this study, thermal analysis for LAT of square bar was performed using laser heat source projection method. And, the analysis results were compared with the results of the prior study of numerical calculation method. It is thus shown that the proposed method is efficient for the thermal analysis of a shaped bar.
Effects of Process Parameters on Laser Ablation Based Machining and Measurements
Jeong, Sung-Ho ; Lee, Seok-Hee ;
Journal of the Korean Society for Precision Engineering, volume 28, issue 12, 2011, Pages 1359~1365
The changes of ablation characteristics with respect to laser parameters and material parameters during pulsed laser ablation of solids were discussed with experimental results. Although laser wavelength, laser pulse width, and laser pulse energy are the primary factors to be considered, it is shown that other parameters such as laser spot size and material properties also critically influence on the ablation results. It is further demonstrated that the microstructural characteristics of the target can lead to completely different ablation rate and surface morphology.
Workpiece Horizontality and Reference Positioning of Cutting Tool by Measuring Impedance in Ultra-Precision-Machining
Lee, Ho-Cheol ; Kim, Gi-Dae ;
Journal of the Korean Society for Precision Engineering, volume 28, issue 12, 2011, Pages 1366~1371
In ultra precision machining, it is necessary to adjust the horizontality and reference position of a workpiece in a noncontact manner. For this, a simple process by measuring impedance between a tool tip and a workpiece which are connected to impedance analyzer is proposed. As the distance between the tool and the workpiece gets closer, the reduction rate of impedance becomes higher over all frequency ranges. By setting threshold value of impedance reduction rate at specific frequencies through preliminary experiments, the distance between the tool and the workpiece can be predicted and it directly enables us to horizontalize the workpiece and to set the tool to the desired reference position.
A Study on the Fail Safety Logic of Smart Air Conditioner using Model based Design
Kim, Ji-Ho ; Kim, Byeong-Woo ;
Journal of the Korean Society for Precision Engineering, volume 28, issue 12, 2011, Pages 1372~1378
The smart air condition system is superior to conventional air condition system in the aspect of control accuracy, environmental preservation and it is foundation for intelligent vehicle such as electric vehicle, fuel cell vehicle. In this paper, failure analyses of smart air condition system will be performed and then sensor fusion technique will be proposed for fail safety of smart air condition system. A sensor fusion logic of air condition system by using CO sensor,
sensor and VOC,
sensor will be developed and simulated by fault injection simulation. The fusion technology of smart air condition system is generated in an experiment and a performance analysis is conducted with fusion algorithms. The proposed algorithm adds the error characteristic of each sensor as a conditional probability value, and ensures greater accuracy by performing the track fusion with the sensors with the most reliable performance.
High-Accuracy Motion Control of Linear Synchronous Motor Using Reinforcement Learning
Jeong, Seong-Hyen ; Park, Jung-Il ;
Journal of the Korean Society for Precision Engineering, volume 28, issue 12, 2011, Pages 1379~1387
A PID-feedforward controller and Robust Internal-loop Compensator (RIC) based on reinforcement learning using random variable sequences are provided to auto-tune parameters for each controller in the high-precision position control of PMLSM (Permanent Magnet Linear Synchronous Motor). Experiments prove the well-tuned controller could be reduced up to one-fifth level of tracking errors before learning by reinforcement learning. The RIC compared to the PID-feedforward controller showed approximately twice the performance in reducing tracking error and disturbance rejection.
Design and Fabrication of Coaxial Rotorcraft-typed Micro Air Vehicle for Indoor Surveillance and Reconnaissance
Byun, Young-Seop ; Shin, Dong-Hwan ; An, Jin-Ung ; Song, Woo-Jin ; Kim, Jeong ; Kang, Beom-Soo ;
Journal of the Korean Society for Precision Engineering, volume 28, issue 12, 2011, Pages 1388~1396
This paper is focused on the procedure of the development of a micro air vehicle which has vertical take-off and landing capability for indoor reconnaissance mission. Trade studies on mission feasibility led to the proposal of a coaxial rotorcraft configuration as the platform. The survey to provide a guide for preliminary design were conducted based on commercial off-the-shelf platform, and the rotor performance was estimated by the simple momentum theory. To determine the initial size of the micro air vehicle, the modified conventional fuel balance method was applied to adopt for electric powered vehicle, and the sizing problem was optimized with the sequential quadratic programming method using MATLAB. The designed rotor blades were fabricated with high strength carbon composite material and integrated with the platform. The developed coaxial rotorcraft micro air vehicle shows stable handling quality with manual flight test in indoor situation.
Tolerance Analysis of Automobile Steering System
Lee, Jang-Yong ;
Journal of the Korean Society for Precision Engineering, volume 28, issue 12, 2011, Pages 1397~1402
Quality of manufactured goods under mass production system depends largely upon accuracy rate of quality control. Tolerance analysis is a useful method to set up a guide for inspection of product. However it usually would happen that strict tolerance provoke very high manufacturing cost. It is the main concern of tolerance analysis to find optimal values of tolerance to satisfy both quality and cost. This paper presents three tolerance analysis methods and its corresponding results upon automobile steering system to analysis the merits and demerits of each method.
Creep Characteristic of the Polymethyl Methacrylate(PMMA) at Stresses and Temperatures
Kang, Suk-Choon ;
Journal of the Korean Society for Precision Engineering, volume 28, issue 12, 2011, Pages 1403~1410
Creep characteristic is an important failure mechanism when evaluating engineering materials that are soft material as polymers or used as mechanical elements at high temperatures. One of the popular thermo-elastic polymers, Polymethyl methacrylate(PMMA) which is used broadly for engineering polymer, as it has excellent mechanical and thermal properties compared to other polymers, was studied for creep characteristic at various level of stresses and temperatures. From the experimental results, the creep limit of PMMA at room temperature is 85 % of tensile strength. which is higher than that of PE (75%)at room temperature. Also the creep limits decreased to nil linearly as the temperatures increased, up to
of the melting point(
). Also the first and third stage among the three creep stages were non-existent nor were there any rupture failure which occurred for many metals at high temperatures.
Discharge Evaluation Program Development of Anti-surge Valve for FPSO Fuel Gas Compressor System
Park, Hyung-Wook ; Lee, Seung-Min ; Cho, Jong-Rae ;
Journal of the Korean Society for Precision Engineering, volume 28, issue 12, 2011, Pages 1411~1418
In this study, to avoid surging in the system as a way to ensure the proper discharge requires the design of the valve capacity rating objective is to develop a program. Approximation algorithm for the capacity evaluation is suggested. Loss coefficients obtained by the algorithm is calculated put in the governing equation for the valve flow coefficient and capacity. Calculated values were compared with numerical analysis results for the verifying their validity. The proven formula is created using Excel and it can be easily available the valve design engineers. Creation of analysis models were using a version of Unigraphics NX 4.0, numerical analysis were using a flow analysis commercial program ANSYS CFX 12.0 version. Equations were referenced 'Handbook of Hydraulic Resistance - 3rd Edition'.
Fabrication of Functional ZnO Nano-particles Dispersion Resin Pattern Through Thermal Imprinting Process
Kwon, Moo-Hyun ; Lee, Heon ;
Journal of the Korean Society for Precision Engineering, volume 28, issue 12, 2011, Pages 1419~1424
Nanoimprint lithography is a next generation lithography technology, which enables to fabricate nano to micron-scale patterns through simple and low cost process. Nanoimprint lithography has been applied in various industry fields such as light emitting diodes, solar cells and display. Functional patterns, including anti-reflection moth-eye pattern, photonic crystal pattern, fabricated by nanoimprint lithography are used to improve overall efficiency of devices in that fields. For these reasons, in this study, sub-micron-scaled functional patterns were directly fabricated on Si and glass substrates by thermal imprinting process using ZnO nano-particles dispersion resin. Through the thermal imprinting process, arrays of sub-micron-scaled pillar and hole patterns were successfully fabricated on the Si and glass substrates. And then, the topography, components and optical property of the imprinted ZnO nano-particles/resin patterns are characterized by Scanning Electron Microscope, Energy-dispersive X-ray spectroscopy and UV-vis spectrometer, respectively.
Characteristic Analysis of Lower Limbs Muscles in Young Normal Adults on a Tilting Bed Using an Unstable Platform
Yu, Mi ; Lee, Sun-Yeon ; Piao, Yong-Jun ; Kim, Kyong ; Jeog, Gu-Young ; Kim, Jung-Ja ; Kwon, Tae-Kyu ;
Journal of the Korean Society for Precision Engineering, volume 28, issue 12, 2011, Pages 1425~1433
We investigated an early rehabilitation training system that increase the intensity of patient rehabilitation training to shorten the time it takes for patients to progress to a secondary rehabilitation training stage by allowing patients incapable of self-ambulation. It consisted of tilting bed, unstable platform using strong springs and training program for lower limb rehabilitation. We performed experimental study on the muscular activities of tibialis anterior(TA), soleus(SO), gastrocnemius(GA) in the lower extremities during training of straight line, circle, quardrangle pattern during tilting angle of
. The muscle activities were higher during tilting angle of
. In straight line pattern, the muscle activities were higher by SO, GA and TA during medio-lateral direction, however, by TA, SO and GA during anterio-posterior direction. In circle and quardrangle pattern, the muscle activities were higher by TA, SO and GA during clockwise and counterclockwise direction. The results indicate that the early rehabilitation training system could be applied to improve the lower extremity muscular strength for elderly and patients, especially, stroke.
Evaluation of Electronic Pedal in Commercial Vehicles using Physiology Analysis of Electromyography
Kim, Jae-Jun ; Kim, Kyung ; Shin, Sun-Hye ; Yu, Chang-Ho ; Jeong, Gu-Young ; Oh, Seung-Yong ; Kwon, Tae-Kyu ;
Journal of the Korean Society for Precision Engineering, volume 28, issue 12, 2011, Pages 1434~1440
In this paper, we assessed muscular activities of lower limbs and foot pressure for car and bus drivers according to operating three electronic pedals that we developed. To analyze drivers' physical exhaustion, muscular fatigue of lower limbs was evaluated. Eleven car drivers and six urban bus drivers were participated in this experiment. The virtual driving system was used for the real driving environment. The virtual driving system was comprised of a spring seat, a steering wheel, pedals (clutch, excel and brake pedals), a manual transmission and a virtual driving simulation. For the real vibration like situation on the road, six degree of freedom motion base system was used. Measured muscles were rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA) and gastrocnemius (Gn) muscles. For the quantitative muscular activities, integrated electromyography (IEMG) was analyzed. Muscular fatigues also were analyzed through the analysis of the median frequency. In addition, foot pressures were analyzed and compared through the peak and averaged pressure during the operating three developed electronic pedals. The experiments are conducted with total 17 drivers, 11 general public and 6 drivers. As a result of the analysis, electromyogram and fatigue analysis through intermediate frequency reduction for pedal-1 more efficient than other pedals. And foot pressure also was decreased. Consequently, we suggested the most efficient pedal and method to minimize the amount of cumulative fatigue.