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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 25, Issue 12 - Dec 2008
Volume 25, Issue 11 - Nov 2008
Volume 25, Issue 10 - Oct 2008
Volume 25, Issue 9 - Sep 2008
Volume 25, Issue 8 - Aug 2008
Volume 25, Issue 7 - Jul 2008
Volume 25, Issue 6 - Jun 2008
Volume 25, Issue 5 - May 2008
Volume 25, Issue 4 - Apr 2008
Volume 25, Issue 3 - Mar 2008
Volume 25, Issue 2 - Feb 2008
Volume 25, Issue 1 - Jan 2008
Selecting the target year
Nano-machining Technology Using Electron Beam
Kim, Jae-Gu ; Lee, Jae-Jong ; Cho, Sung-Hak ; Choi, Doo-Sun ; Lee, Eung-Suk ;
Journal of the Korean Society for Precision Engineering, volume 25, issue 3, 2008, Pages 7~14
Study on Electron Optic Analysis for Electron-beam Processes
Lee, Eung-Ki ;
Journal of the Korean Society for Precision Engineering, volume 25, issue 3, 2008, Pages 15~22
FIB-Sputtering Process Technology and Its Application
Kang, Eun-Goo ; Choi, Byoung-Ryul ; Hong, Won-Pyo ; Lee, Seok-Woo ; Choi, Hon-Zong ;
Journal of the Korean Society for Precision Engineering, volume 25, issue 3, 2008, Pages 23~31
Surface Modification of Polymer and Metal by Ion Beam or Plasma
Choi, Sung-Chang ; Han, Jea-Kil ;
Journal of the Korean Society for Precision Engineering, volume 25, issue 3, 2008, Pages 32~43
Simulation of Focused Ion Beam Processes for Micro-Nano Machining
Lee, Hi-Won ; Han, Jin ; Min, Byung-Kwon ; Lee, Sang-Jo ;
Journal of the Korean Society for Precision Engineering, volume 25, issue 3, 2008, Pages 44~49
Tool Shape Compensation Scheme for Formed Turning Tools Shape of Ball Bearing Raceways
Moon, Ho-Keun ; Joung, Jae-Hyun ; Moon, Suck-Chan ; Joun, Man-Soo ;
Journal of the Korean Society for Precision Engineering, volume 25, issue 3, 2008, Pages 50~55
In this paper, we propose a new shape compensation scheme to make up for the difference in groove radius between the formed tools and the machined bearing raceways, which inherently takes place during machining the ball bearing raceways by the turning process using conventional formed tools. The associated conventional methods of the formed tool design and its modification such as a simple depth compensation method and a graphical compensation method are introduced and the latter, which has been known to be the better of the two, is experimentally investigated in detail to reveal its drawback. The algorithm is given and it is applied to develop a formed tool design program. The program developed by the presented approach is successfully applied to design the formed turning tool for the bearing raceways.
Mirror Finishing of Co-Cr-Mo Alloy by Ultrasonic Elliptical Vibration Cutting Method
Song, Young-Chan ; Tanaka, Kenichi ; Moriwaki, Toshinmichi ;
Journal of the Korean Society for Precision Engineering, volume 25, issue 3, 2008, Pages 56~62
The biocompatibility and the fatigue strength of Co-Cr-Mo alloy are excellent, so it is used well for the material of artificial joints. The head of artificial joint needs mirror surface for reduction of abrasive resistance. Mirror finishing of Co-Cr-Mo alloy with geometrically defined single crystal diamond cutting tools is handicapped by micro chipping of tool edge. In general, it is said that the micro chipping of diamond tool is caused by work hardening of Co-Cr-Mo alloy for the cut. In the present research, mirror finishing of Co-Cr-Mo alloy by applying ultrasonic elliptical vibration cutting was carried out. The experimental results show that the micro chipping of diamond tool was suppressed and the tool wear was remarkably reduced as compared with the ordinary diamond cutting without elliptical vibration motion. It was confirmed that the good mirror surface of maximum surface roughness of 25 nmP-V was obtained for the cutting length of about 14 m. It is expected that mirror finishing of Co-Cr-Mo alloy can be achieved by applying ultrasonic elliptical vibration cutting practically.
Electrostatic Suspension System Using Time Optimal Control
Jeon, Jong-Up ; Baik, Bong-Woo ; Ngo, Hung Manh ; Park, Kyu-Yeol ;
Journal of the Korean Society for Precision Engineering, volume 25, issue 3, 2008, Pages 63~72
A new method for the electrostatic suspension of disk-shaped objects is proposed which is based on a time-optimal control scheme and deploys only high-voltage power supplies that can deliver dc voltages of positive and/or negative polarity. This method possesses the unique feature that no high-voltage amplifiers are needed which leads to a remarkable system simplification and objects can be suspended stably even in vacuum environment. Using this scheme, an aluminium disk used in a 3.5-inch HDD was suspended stably at an airgap of 0.3mm.
Phenomenological Damping Flow Modeling and Performance Evaluation for a Continuous Damping Control Damper Using MR Fluid
Park, Jae-Woo ; Jung, Young-Dae ;
Journal of the Korean Society for Precision Engineering, volume 25, issue 3, 2008, Pages 73~82
Recently MR CDC damper has been applied to semi-active suspension control system gradually. Compared to former hydraulic CDC damper, it has rapid time response performance as well as simple internal structure and wide range of damping force. In order to develop control logic algorithm which enables to take maximum advantage of unique characteristics of MR CDC damper, it is inevitable to perform a thorough investigation into its nonlinear performance. In many previous researches, MR fluid model was either simply assumed as Bingham Plastic, or a phenomenological model based on experiment was established instead to predict damping performance of MR CDC damper. These experimental flow model which is not based on flow analysis but intentionally built to fit damping characteristics, may lead to totally different results in case of different configuration or structure of MR CDC damper. In this study, a generalized flow formula from mathematical flow model of MR fluid for annular orifice is derived to analyze and predict damping characteristics when current is excited at piston valve.
Fault Tolerant Homopolar Magnetic Bearings with Flux Coupling
Na, Uhn-Joo ;
Journal of the Korean Society for Precision Engineering, volume 25, issue 3, 2008, Pages 83~92
This paper develops the theory for a fault-tolerant, permanent magnet biased, homopolar magnetic bearing. If some of the coils or power amplifiers suddenly fail, the remaining coil currents change via a novel distribution matrix such that the same magnetic forces are maintained before and after failure. Lagrange multiplier optimization with equality constraints is utilized to calculate the optimal distribution matrix that maximizes the load capacity of the failed bearing. Some numerical examples of distribution matrices are provided to illustrate the theory. Simulations show that very much the same dynamic responses (orbits or displacements) are maintained throughout failure events (up to any combination of 3 coils failed for the 6 pole magnetic bearing) while currents and fluxes change significantly. The overall load capacity of the bearing actuator is reduced as coils fail. The same magnetic forces are then preserved up to the load capacity of the failed.
Development of ESPI System Using a Modulating LASER
Lee, Kun-Young ; Kang, Young-June ; Park, Nak-Kyu ; Lee, Dong-Hwan ;
Journal of the Korean Society for Precision Engineering, volume 25, issue 3, 2008, Pages 93~100
Laser interferometry is widely used as a measuring system in many fields because of its high resolution and ability to measure a broad area in real-time all at once. In conventional LASER interferometry, for example Out-of-plane ESPI(Electronic Speckle Pattern Interferometry), In plane ESPI, Shearography and Holography, it uses PZT or other components as a phase shift instrumentation to extract 3D deformation data, vibration mode and others. However, in most cases PZT has some disadvantages, which include nonlinear errors and limited time of use. In the present study, a new type of LASER interferometry using a laser diode is proposed. Using LASER Diode Sinusoidal Phase Modulating (LD-SPM) interferometry, the phase modulation can be directly modulated by controlling the LASER Diode injection current thereby eliminating the need for PZT and its components. This makes the interferometry more compact. This paper reports on a new approach to the LD Modulating interferometry that involves four-buckets phase shift method. This study proposes a four-bucket phase mapping algorithm, which was developed to have a guaranteed application, to stabilize the system in the field and to be a user-friendly GUI. In this paper, the theory for LD wavelength modulation and sinusoidal phase modulation of LD modulating interferometry is shown. Four-bucket phase mapping algorithm is then introduced.
A Study on Welding Residual Stress Measurement by Laser Inteferometry and Spot Heating Method
Hong, Kyung-Min ; Lee, Dong-Hwan ; Kang, Young-June ;
Journal of the Korean Society for Precision Engineering, volume 25, issue 3, 2008, Pages 101~108
Residual stress is one of the causes which make defects in engineering components and materials. Many methods have been developing to measure the residual stress. Though these methods provide the information of the residual stress, they also have disadvantage like a little damage, time consumption, etc. In this paper, we devised a new experimental technique to measure residual stress in materials with a combination of laser speckle pattern interferometry and spot heating. The speckle pattern interferometer measures in-plane deformation during the heat provides for much localized stress relief. 3-D shape is used for determining heat temperature and other parameters. The residual stresses are determined by the amount of strain that is measured subsequent to the heat and cool-down of the region being interrogated. A simple model is presented to provide a description of the method. In this paper, we could experimentally confirm that residual stress can be measured by using laser interferometry and spot heating method.
Study on the Characteristics of Surge Pressure by High Frequency PWM Control in Braking System
Kim, Byeong-Woo ;
Journal of the Korean Society for Precision Engineering, volume 25, issue 3, 2008, Pages 109~114
The solenoid valve of ABS hydraulic modulator is a two directional on-off valve and is controlled by around 100Hz on-off control. When the on-off valve is switched from open state to closed state, there are braking force deterioration, noise and vibration due to surge pressure in the wheel cylinder. In this study, identifies surge pressure in the braking process of ABS, and investigates the way to reduce the phenomenon. To reduce the surge pressure, PWM(Pulse Width Modulation) control with high frequency of 20kHz was attempted. In conclusion, by using the results of this study for the pressure surge prediction, we could expect enhancement of braking performance in ABS.
A Study on Thermal and Modal Characteristics for EGR System with Dimpled Rectangular Tube
Seo, Young-Ho ; Heo, Sung-Chan ; Kwon, Young-Seok ; Ku, Tae-Wan ; Kim, Jeong ; Kang, Beom-Soo ;
Journal of the Korean Society for Precision Engineering, volume 25, issue 3, 2008, Pages 115~125
Recently, Exhaust Gas Recirculation (EGR) system which re-flow a cooled exhaust gas from vehicles burning diesel as fuel to a combustion chamber of engine has been used to solve the serious air pollution. For the design and mass production of EGR system, it is essential to ensure structural integrity evaluation. The EGR system consisted of ten dimpled oval core rectangular tubes, two fix-plates, two coolant pipes, shell body and two flanges in this study. To confirm the safety of the designed system, finite element modeling about each component such as the dimpled oval core tube with the dimpled shape and others was carried out. The reliability of EGR system against exhaust gas flow with high temperature was investigated by flow and pressure analysis in the system. Also, thermal and strength analysis were verified the safety of EGR system against temperature change in the shell and tubes. Furthermore, modal analysis using ANSYS was also performed. From the results of FE analysis, there were confirmed that EGR system was safe against the flow of exhaust gas, temperature change in EGR system and vibration on operation condition, respectively.
A Study for Improvement of Temperature Distribution in Plunger Surface Cooling
Kwak, Kyung-Min ; Park, Ji-Yeol ; Bai, Cheol-Ho ;
Journal of the Korean Society for Precision Engineering, volume 25, issue 3, 2008, Pages 126~133
The main objective of the present study is to achieve linear temperature distribution of cooling surface of plunger. K type thermocouples are attached at the surface of plunger to measure temperature. Nozzle and insulating material are inserted in the pin hole of the plunger for this study. Cooling water flow enters at one nozzle and leaves at three nozzles. Flow through nozzle can be activated in the pin hole, temperature of hot point around hole is decreased. Meanwhile, insulating material blocks off heat transfer, temperature of cold point around hole is increased. By combination of nozzle and insulation, heat transfer of hole is controlled effectively, as result its, temperature of plunger surface shows linear temperature distribution.
Micro Electrochemical Machining of Stainless Steel Using Citric Acid
Ryu, Shi-Hyoung ;
Journal of the Korean Society for Precision Engineering, volume 25, issue 3, 2008, Pages 134~140
Micro electrochemical machining (ECM) is conducted on stainless steel 304 using non-toxic electrolyte of citric acid. Electrochemical dissolution region is minimized by applying a few hundred second duration pulses between the tungsten SPM tip and the work material. ECM characteristics according to citric acid concentration, feeding velocity and electric conditions such as pulse amplitude, pulse frequency, and offset voltage are investigated through a series of experiments. Micro holes of
in diameter with the depth of
in diameter with the depth of
are perforated. Square and circular micro cavities are also manufactured by electrochemical milling. This research can contribute to the development of safe and environmentally friendly micro ECM process.
Development of Wearable Robot for Elbow Motion Assistance of Elderly
Jang, Hye-Yoen ; Han, Chang-Soo ; Kim, Tae-Sik ; Jang, Jae-Ho ; Han, Jung-Soo ;
Journal of the Korean Society for Precision Engineering, volume 25, issue 3, 2008, Pages 141~146
The purpose of this study is to develop the algorithm which can control muscle power assist robot especially for elderly. Recently, wearable robots for power assistance are developed by many researchers, and its application fields are also variable such as for medical or military equipment. However, there are many technical barriers to develop the wearable robot. This study suggest a control method improving performance of a wearable robot system by using a EMG signal of major muscles and a force sensor signal as command signal of system. The result of the robot Prototype efficiency experiment, the case of Maximum Isometric motion it suggest 100% power of muscle, the man need only 66% of MVIC(Maximum Voluntary Isometric Contraction) to lift 5kg dumbbell without robot assist. However the man needs only 52% of MVIC to lift 5kg dumbbell with robot assist. Therefore 20% muscle power increased with robot assist. Also, we designed light weight robot mechanism that extract the command signal verified and drive the wanted motions.
Efficient Calculation of Distance Fields Using Cell Subdivision
Yoo, Dong-Jin ;
Journal of the Korean Society for Precision Engineering, volume 25, issue 3, 2008, Pages 147~156
A new approach based on cone prism intersection method combined with sorting algorithm is proposed for the fast and robust signed distance field computation. In the method, the space bounding the geometric model composed of triangular net is divided into multiple smaller cells. For the efficient calculation of distance fields, valid points among the triangular net which will generate minimum distances with current cell are selected by checking the intersection between current cell and cone prism generated at each point. The method is simple to implement and able to achieve an order of magnitude improvement in the computation time as compared to earlier approaches. Further the method is robust in handling the traditional sign problems. The validity of the suggested method was demonstrated by providing numerous examples including Boolean operation, shape deformation and morphing of complex geometric models.
An Algorithm to Speed Up the Rapid Prototyping
Ko, Min-Suk ; Chang, Min-Ho ; Wang, Gi-Nam ; Park, Sang-Chul ;
Journal of the Korean Society for Precision Engineering, volume 25, issue 3, 2008, Pages 157~164
While developing physical prototype from CAD model, rapid prototyping mainly focuses on two key points reducing time and material consumption. So, we have to change from a traditional solid model to building a hollowed prototype. In this paper, a new method is presented to hollow out solid objects with uniform wall thickness to increase RP efficiency. To achieve uniform wall thickness, it is necessary to generate internal contour by slicing the offset model of an STL model. Due to many difficulties in this method, this paper proposes a new algorithm that computes internal contours computing offset model which is generated from external contour using wall thickness. Proposed method can easily compute the internal contour by slicing the offset surface defined by the sum of circle swept volumes of external contours without actual offset and the circle wept volumes. Internal contour existences are confirmed by using the external point. Presented algorithm uses the 2D geometric algorithm allowing RP implementation more efficient. Various examples have been tested with implementation of the algorithm, and some examples are presented for illustration.
The Stress Distribution Property on the Customized Ankle Foot Orthoses During the Gait Period
Choi, Young-Chul ; Rhee, Kun-Min ; Choi, Hwa-Soon ;
Journal of the Korean Society for Precision Engineering, volume 25, issue 3, 2008, Pages 165~175
An ankle-foot orthosis(AFO) is a brace for persons with gait disabilities to support or replace the function of ankle joint. Ankle-foot orthoses(AFO's) are usually prescribed to alleviate the drop-foot by constraining the excessive plantar flexion. The shape and the strength of the AFO are often based on 'trial and error' due to a lack of knowledge of the stress distribution in the AFO. In this study, an improved stress-freezing method was proposed to measure the stress distribution characteristics in the AFO. As a result, a photoelastic material with low freezing temperature was developed to measure the stresses under a person's direct contact loading condition. The three-dimensional stress-1rozen photoelastic models of AFO's for five stages of stance phase such as heel contact, foot flat, mid stance, heel off, and toe off were produced. The results of photoelastic analysis revealed that the stresses developed in the AFO were varied considerably from tensile to compressive or vice versa, during walking. At the posterior part of ankle joint in the AFO, the maximum compressive stress of 1.81MPa was observed in the mid stance, and the maximum tensile stress of 0.74MPa was observed during heel contact. The overall stress levels in the AFO's were low in the toe off phase. The results suggested that the posterior part of ankle joint might be the most fragile part in the AFO.