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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Precision Engineering
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Journal DOI :
Korean Society of Precision Engineering
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Volume & Issues
Volume 15, Issue 12 - Dec 1998
Volume 15, Issue 11 - Nov 1998
Volume 15, Issue 10 - Oct 1998
Volume 15, Issue 9 - Sep 1998
Volume 15, Issue 8 - Aug 1998
Volume 15, Issue 7 - Jul 1998
Volume 15, Issue 6 - Jun 1998
Volume 15, Issue 5 - May 1998
Volume 15, Issue 4 - Apr 1998
Volume 15, Issue 3 - Mar 1998
Volume 15, Issue 2 - Feb 1998
Volume 15, Issue 1 - Jan 1998
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Geometry Design of Omni-directional Mecanum Wheel
Journal of the Korean Society for Precision Engineering, volume 15, issue 3, 1998, Pages 11~17
The mecanum wheel was originaly developed in sweden to realize the omni-directional motion of the cart. The circumference of each wheel is lined with rollers set at 45 degrees relative to the main wheel. This paper proves that the roller of the mecanum wheel shapes the ellipsoid, derives the kinematic relationships between the parameters of the wheel and rollers, and proposes the procedure to determine the parameters of the wheel. The result was implemented into the computer program for the design of the mecanum wheel.
An Automated Process Planning System for Blanking or Piercing of Irregular Shaped Sheet Metal Product with Bending Processes
Journal of the Korean Society for Precision Engineering, volume 15, issue 3, 1998, Pages 18~23
This paper describes a research work of developing a computer-aided design of blanking and piercing for irregular-shaped sheet metal products. An approach to the CAD system is based on the knowledge-based rules. Knowledge for the CAD system is formulated from plasticity theories, experimental results and the empirical knowledge of field experts. The system has been written in AutoLISP on the AutoCAD with a personal computer and is composed of four main modules, which are input and shape treatment, flat pattern layout, production feasibility check, and strip layout module. Based on knowledge-based rules, the system is designed by considering several factors, such as radius and angle of bend. material and thickness of product, complexities of blank geometry and punch profile, and availability of press. This system is capable of unfolding a formed sheet metal part to give flat pattern and automatically account for the adjustment of bend allowances to match tooling requirements by checking the dimensions and relationships of parts of the folded product. Also this system can carry out a process planning which is obtained from results of irregular shape of product that was successful in production feasibility check module according to flat pattern layout and generate strip layout drawing in graphic forms. The developed system provides its efficiency for flat pattern layout, and strip layout for the irregularly shaped sheet metal products.
Analysis of Strength and Displacement of Jig Body in Index Machine
Journal of the Korean Society for Precision Engineering, volume 15, issue 3, 1998, Pages 24~30
Strength and displacement of jig body in index machine utilized for multiprocess machining such as drilling, boring and tapping, etc, at the same time were analyzed by the use of finite element analysis soft ware ANSYS 5.2A. The whole geometry was constructed by 4048 elements and 7016 nodes employing 8 node brick element. The analyses were carried out on five loading cases combining vertical and horizontal machining to simulate the case occurring large displacement and the one occurring small displacement one and provided following conclusions. (1) Jig body had sufficient strength because its safety factor was 6.95 even in the most severe loading case. (2) The largest displacement in Z direction was 549 m and that in radial direction was 43.7 m. (3) In order to reduce the displacement, vertical machining rather than horizontal or two or three processes should be adopted in the same station. (4) Alternate change of horizontal machining direction at consecutive stations can reduce the displace ment. (5) The dimension of the slider should be increased to reduce the displacement by the tolerance in the sliding part. (6) A bypass idle piston head needs to be installed to give a counterpart supporting load from opposite direction for a single horizontal machining case.
Stress Analysis of the Spherical Satellite Propellant Tank With Respect to the Change of Location of the Lug and Tank Wall Thickness
Journal of the Korean Society for Precision Engineering, volume 15, issue 3, 1998, Pages 31~37
The structure of satellite consists of six parts which are control system, power system, thermal control system, remote measurement command system, propellant system and thrust system. In these parts, propellant system consists of propellant tank and thrust device. What we want to perform is optimum design to minimize the weight of propellant tank. In order to design optimal propellant tank, several parameters should be adopted from the tank geometry like the relative location of the lug and variation of the wall thickness. The analysis was executed by finite element analysis for finding optimal design parameters. The structure was divided into three parts consisting of the initial thickness zone, the transitional Bone, and the weak zone, whose effects on the pressure vessel strength was investigated. Finally the optimal lug location and the three zone thickness were obtained and the weight was compared with the uniform thickness vessel.
Development of the 4th Generation CD Optical Pick-up with Small Thickness
Journal of the Korean Society for Precision Engineering, volume 15, issue 3, 1998, Pages 38~49
The 3rd generation optical pick-up used popularly in resent years is composed of many optical and electronic components such as laser diode, photo diode, beam splitter, objective lens, grating lens, concave lens, collimator lens etc. Therefore, the design of its optical system and its main base which the said optical and electronic components are set on, is complicated and needs high precision. Its assembly and adjustment in the production line is also difficult. This complication and the demand of high precision get its production cost to be high and its reliability to be low. In this paper, the 4th generation optical pick-up is designed and developed, with the hologram device which laser diode. photo diode, beam splitter. and grating lens are integrated in. This optical pick-up reduces the number of points of adjustment by 3, compared with the 3rd generation optical pick-up of which the number of points of adjustment is 6. This optical pickup also decreases by 4 the number of points of W bonding to have bad influence on environmental reliability, decreases by about 10 the number of parts, and establishes about 20% cost-down of material cost, compared with the 3rd generation optical pick-up.
Statistical Process Control System for Continuous Flow Processes Using the Kalman Filter and Neural Network′s Modeling
Journal of the Korean Society for Precision Engineering, volume 15, issue 3, 1998, Pages 50~60
This paper is concerned with the design of two residual control charts for real-time monitoring of the continuous flow processes. Two different control charts are designed under the situation that observations are correlated each other. Kalman-Filter based model estimation is employed when the process model is known. A black-box approach, based on Back-Propagation Neural Network, is also applied for the design of control chart when there is no prior information of process model. Performance of the designed control charts and traditional control charts is evaluated. Average run length(ARL) is adopted as a criterion for comparison. Experimental results show that the designed control chart using the Neural Network's modeling has shorter ARL than that of the other control charts when process mean is shifted. This means that the designed control chart detects the out-of-control state of the process faster than the others. The designed control chart using the Kalman-Filter based model estimation also has better performance than traditional control chart when process is out-of-control state.
Establishment of Prototyping System for Drag-Valve Disk Using RP
Journal of the Korean Society for Precision Engineering, volume 15, issue 3, 1998, Pages 61~67
Rapid prototyping becomes widely used in design and manufacturing of mechanical and aerospace engineering. Here a drag valve disk consisted of complicate configuration has designed by CAD, and prototyped by a stereolithography apparatus (SLA) to confirm the design configuration. Also the prototyped valve disk was used for checking if it could be applied for casting from the view point of accuracy, cost, and time. The rapid-prototyped disk by SLA was compared with a high-speed machined disk by MAKINO V55, and it is found that the prototyping of the disk by SLA appears more economical, more accurate and faster than by machining with MAKINO V55.
Design Evaluation of Pickup Device Collecting Deep-Sea-Manganese Nodules
Journal of the Korean Society for Precision Engineering, volume 15, issue 3, 1998, Pages 68~74
Performance and efficiency of deep seabed collector is a primary factor for feasibility of commercial deep ocean mining. The efficiency of manganese nodules collector depends on vehicle mobility relative to undulating seafloor and is attributed pickup head to keep altitude and elevation of it against seafloor. For this reason, motion control of pickup head relative to the changing deep-sea topography and other disturbances is of particular importance in design of pickup device. The concept of design axiom is applied to a pickup device of hybrid type in order to evaluate the concept design. Kinematic analysis conducted in absolute Cartesian coordinates gives position, velocity, and acceleration of the hydraulic cylinders which enable the pickup head to keep the preset optimal distance from seafloor. Inverse dynamic analysis provides the driving forces of hydraulic cylinders and the reaction forces at each joint. Design sensitivity analysis is performed in order to investigate the effects of possible design variables on the change of the maximum strokes of hydraulic cylinders. The direct differentiation method is used to obtain the design sensitivity coefficients.
자기변형재료를 이용한 절삭공구용 마이크로포지쇼너의 개발
Journal of the Korean Society for Precision Engineering, volume 15, issue 3, 1998, Pages 75~81
In the machining process, variation in cutting forces results in relative displacements between the tool and the workpiece leading to tool vibration. Also there is a demand to change the depth of cut very frequently. One solution for the both cases is to develop a system which has the ability to reposition a cutting tool to a very small level, i.e., micron. This paper presents the development of a micropositioner using a magnetostrictive material. The developed micropositioner is implemented to a lathe and subjected to various tests. The results show that the micropositioner with a magnetostrictive actuator has good potential for machining application.
Integration of Process Planning and Operations Scheduling by Process Net Model and Genetic Algorithm
Journal of the Korean Society for Precision Engineering, volume 15, issue 3, 1998, Pages 82~87
In order to provide a manufacturing system with efficiency and flexibility to cope with the changes in shop floor status, the integration of process planning and operations scheduling is required. In this paper, an integrated system of process planning and operations scheduling based on the concept of process net model and genetic algorithm is suggested. The process net model includes the alternative process plans. The integrated system is applied for prismatic parts.
Feasible Design Area of 4 Bar Input Crank for 3 Position Synthesis of Watt-II 6 Bar Mechanism
Journal of the Korean Society for Precision Engineering, volume 15, issue 3, 1998, Pages 88~98
In many automatization applications, a rigid body is required to go forward and backward repeatedly through a set of given position/orientations precisely while a crank is rotated. Such a motion can be generated by 6 bar mechanism adding a dyad to a 4 bar mechanism. If this is the case for 3 position synthesis of the 4 bar mechanism, the feasible solution area for designing the 4 bar mechanism will be limited over the general solution area. This paper proposes a procedure to synthesize 4 bar mechanism to be used to generate the required motion. It is found that the only input crank of the 4 bar mechanism should be limited to satisfy the condition. And the feasible design area for the circle point/ center point of the input crank is identified so that design of the undesired mechanism could be avoided. The method is tested and the results are shown.
Analysis and Control f Contact Mode AFM
Journal of the Korean Society for Precision Engineering, volume 15, issue 3, 1998, Pages 99~106
Recently, scientists introduced a new type of microscope capable of investigating nonconducting surfaces in an atomic scale, which is called AFM (Atomic Force Microscope). It was an innovative attempt to overcome the limitation of STM (Scanning Tunnelling Microscope) which has been able to obtain the image of conducting surfaces. Surfaces of samples are imaged with atomic resolution. The AFM is an imaging tool or a profiler with unprecedented 3-D resolution for various surface types. The AFM technology, however, leaves a lot of room for improvement due to its delicate and fragile probing mechanism. One of the room for improvements is gap control between probe tip and sample surface. Distance between probe tip and sample surface must be kept in below one Angtrom in order to measure the sample surface in Angstrom resolution. In this paper, AFM system modeling, experimental system identification and control scheme based on system identification are performed and finally sample surface is measured by home-built AFM with such a control scheme.
Two-Phase Neuro-System Identification Based on Artificial System
Journal of the Korean Society for Precision Engineering, volume 15, issue 3, 1998, Pages 107~118
Two-phase neuro-system identification method is presented. The 1
-phase identification uses conventional neural network mapping for modeling an input-output system. The 2
-phase modeling is also performed sequentially using the 1
-phase modeling errors. In the 2
a phase modeling, newly generated input signals, which are obtained by summing the 1st-phase modeling error and artificially generated uniform series, are utilized as system's I-O mapping elements. The 1
-phase identification is interpreted as a “Real Model” system identification because it uses system's real data(i.e., observations and control inputs) while the 2
-phase identification as a “Artificial Model” identification because of using artificial data. Experimental results are given to verify that the two-phase neuro-system identification could reduce the overall modeling errors.rrors.
An Investigation of the Bendability of Glass Fiber Reinforced Thermoplastic Composite Sheet
Joong-Hee Lee ; K. Y. Rhee ;
Journal of the Korean Society for Precision Engineering, volume 15, issue 3, 1998, Pages 119~126
Dynamic Control of a Robot with a Free Wheel
Journal of the Korean Society for Precision Engineering, volume 15, issue 3, 1998, Pages 127~132
Mobile wheeled robots are nonholonomically constrained systems. Generally, it is very difficult to describe the motion of mechanical systems with nonintegrable nonholonomic constraints. An objective of this study is to describe the motion of a robot with a free wheel. The motion of holonomically and/or nonholonomically constrained system can be simply determined by Generalized Inverse Method presented by Udwadia and Kalaba in 1992. Using the method, we describe the exact motion of the robot and determine the constraint force exerted on the robot for satisfying constraints imposed on it. The application illustrates the ease with which the Generalized Inverse Method can be utilized for the purpose of control of nonlinear system without depending on any linearization, maintaining precision tracking motion and explicit determination of control forces of nonholonomically constrained system.
Wear Debris Identification of the Lubricated Machine Surface with Neural Network Model
Journal of the Korean Society for Precision Engineering, volume 15, issue 3, 1998, Pages 133~140
The neural network was applied to identify wear debris generated from the lubricated machine surface. The wear test was carried out under different experimental conditions. In order to describe characteristics of debris of various shapes and sizes, the four shape parameter(50％ volumetric diameter, aspect, roundness and reflectivity) of wear debris are used as inputs to the network and learned the friction condition of five values(material 3, applied load 1, sliding distance 1). It is shown that identification results depend on the ranges of these shape parameter learned. The three kinds of the wear debris had a different pattern characteristics and recognized the friction condition and materials very well by neural network.
A Study on the Cutting Conditions of Self-Induced Chattering in Micro Shaping with Diamond Tool
Journal of the Korean Society for Precision Engineering, volume 15, issue 3, 1998, Pages 141~149
Diamond shaping is one of the machining strategies to make the optical micro-groove molds, and it is especially useful when the component is an assembly of the linear micro-groove array. A mirrorlike surface and an arbitrary crose-sectional curve can be easily made by the diamond tool. However, the cutting speed of shaping is relatively lower than that of the other cutting methods, and there exist an unstable cutting conditions that generate the chatter. This study is focused on the modeling of the simplified self-induced chatter of the diamond shaping, and the machinabilities of three materials are compared by cutting experiments. From the chatter model and experiments, it is found that the unstable cutting conditions exist when the depth of cut is low and cutting speed is high. It is also found that the brass is relatively good material in micro shaping than copper or aluminium from the cutting experiments.
A Study on the Dynamic Modeling of a Hydrostatic Table
Journal of the Korean Society for Precision Engineering, volume 15, issue 3, 1998, Pages 150~156
In this paper, a 3-DOF(Degree Of Freedom) rigid body model is developed for dynamic analysis of a hydrostatic table. The dynamic coefficients, stiffness and damping constant of each pad are calculated from the mass flow continuity condition. The validity of this model is examined in theoretical and experimental method. The dynamic behavior when mass unbalances and local variations of stiffness and damping of pads present is analyzed for real applications of hydrostatic table. Since the theoretical and experimental results show goof agreement. it can be said that the 3-DOF rigid body model is useful for the dynamic model of the table. The analysis reveals that the pitching motion is the dominant mode of vibration, It also reveals that unbalanced loads can increase amplitude of tilting motion and reduce natural frequencies and damping capacity of the hydrostatic table.
A Study on the Trajectory Optimization Planning of Biped Walking Machine
Journal of the Korean Society for Precision Engineering, volume 15, issue 3, 1998, Pages 157~167
In this paper it is purpose that reduces joint torques and their rate of change through optimizing trajectory planning of biped walking machine. The motion of biped walking machine is divided into leg motion for walking and body motion for keeping balance. The leg motion is planned by three phases, that are deploy, swing, and place phases, in terms of the state of foot against floor. The distribution of time assigned to each phase is optimized and that causes leg joint torques and their rate of change to minimize. The body notion is produced by using optimal control theory which minimizes body joint torques and satisfies Z.M.P. constraints defined as region of each phase.