• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.5
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• pp.94-101
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• 2013

Injection molding process is one of the most important methods to produce plastic parts with high efficiency and low cost. The objective of this study is to implement the best plastic injection molding process for LED TV speaker frame. Moldflow analysis and simulation of plastic injection molding process were carried out in order to predict optimal modeling operation conditions and then injection molded part was produced various type of resin temperature, filling time and injection pressure variation. the result was that the best injection molding condition is set as 60bar pressure, 2sec filling time and $310^{\circ}C$ degree. The study result would be useful to variety of plastic injection molding process.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.484-487
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• 2003

In designing AMBs (active magnetic bearings) for high-speed spindle system, the shaft is usually assumed as a rigid rotor. For automatic tool change process, there should be a tool clamping system with drawbar using spring or hydraulic force, and the drawbar in the spindle can be in various condition of support during design and manufacturing error. In this paper, the modal characteristics of drawbar in high-speed milling spindle system due to supporting stiffness between drawbar and shaft are analyzed by numerical method. The result shows enough stiff supports must be provided between shaft and drawbar to prevent occurring drawbar vibration lower than the natural frequency of 1$\^$st/ bending mode of spindle.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.371-375
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• 2001

The concept of a new linear motor that uses piezo-stack actuator is demonstrated. The working principle is far different from the conventional inchworm motor. This motor is based on the self-moving cell concept. The linear motor has three cells and each cell is constructed with one piezo-stack actuator and a shell structure. A cell train is constructed by connecting these cells and the cell train is fitted into a guide way with a proper interference. The cell train moves along the guide way, by activating each cell in succession. The moving motion of the motor is tested. Since this linear motor uses piezo-stack actuator with unified clamping cell, it can produce fast speed, high resolution and large push force.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.9 s.186
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• pp.76-83
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• 2006

Machining accuracy is closely related with tool deflection induced by cutting forces. In this research, cutting forces and tool deflection in end milling are expressed as a closed form of tool rotational angle and cutting conditions. The discrete cutting fores caused by periodic tool entry and exit are represented as a continuous function using the Fourier series expansion. Tool deflection is predicted by direct integration of the distributed loads on cutting edges. Cutting conditions, tool geometry, run-outs and the stiffness of tool clamping part are considered together far cutting forces and tool deflection estimation. Compared with numerical methods, the presented method has advantages in prediction time reduction and the effects of feeding and run-outs on cutting forces and tool deflection can be analyzed quantitatively. This research can be effectively used in real time machining error estimation and cutting condition selection for error minimization since the form accuracy is easily predicted from tool deflection curve.

• International Journal of Precision Engineering and Manufacturing
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• v.2 no.4
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• pp.40-46
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• 2001

Bulging is a forming method to shape die cavity by using hydraulic pressure in tube or vessel. Bulging machine and die were developed in order to produce vessel for keeping warm. Bulging machine is a double type with two horizontal cylinders for bulging of two pieces at the same time. The developed die system has one bulging die and two drawing dies for necking at both ends of the tube. The diameter of tube expands by hydraulic pressure in tube. At the same time, thrust at both ends of the tube pushes tube in the direction of expansion to obtain high expansion rate with no crack. In this study, the bulging properties were investigated to solve tube crack and necking in manufacturing vessel by combining bulging and drawing. As a result, high expanding rate of tube radius without crack, precision necking and high productivity were obtained.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.04a
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• pp.364-368
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• 1992

The conventional loading process of workpieces for a CNC lathe is performaed either by human or by a general robot. It is not suitable for a general robot to load workpieces because of high price and inefficiency. Starting from the description of the environment around CNC lathes and the analysis ofloading process, we have developed the task-oriented loading manipulator. The characteristics of a loading manipulator are the following: to load/unload heavy workpieces, to decrease the whole porcess time. The air-chuck to load heavy workpiece has high clamping force and light weight. A loading manipulator has accomplished both the integration of independent automation techniques and cost-down effect of product. A loading manupulator developed in this project has been designed for general loading process. The loading manipulator is capable of carrying heavy payload with respect to weight of robot in short cycle time.

• Journal of Drive and Control
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• v.10 no.3
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• pp.21-26
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• 2013

This paper presents a robust motion tracking control of a cylinder-toggle servomechanism for injection molding machines. Virtual design model has been developed for a five-point type toggle mechanism. A sliding function is defined and combined with PID control to accommodate mismatches between the real plant and the linear model used. From tracking control simulations, it is shown that significant reduction in position tracking error is achieved with clamping force build-up through the use of proposed control scheme.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.8
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• pp.71-78
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• 1999

The application range of injection molded parts is expanding by the development of engineering plastics with good mechanical properties. Plastic gears are specially used as automotive parts due to an excellent performance in the characteristics of a strength vs. weight, and the study of injection molding process of plastic gear using Nylon66 is performed in this study. Filling, packing and cooling analyses were done by using the simulation software like Moldflow, and a mold was designed by following the simulation results. Pin-point gates with three points were taken to satisfy the design guides like a full-shot, and lower clamping force and uniform shrinkage. Characteristics of shrinkage of molded gear and temperature difference between cavity and core sides of a mold were shown.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.3
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• pp.59-64
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• 2008

Spindle units of machine tool are very important part in the manufacturing area. Recently high speed machining has become the main issue of metal cutting. To develop high speed machine tools, a lot of studies have been carried out for high speed spindle. Due to increase of the rotational speed of the spindle, there has been renewal of interest in tooling system of high speed spindle. This paper concerns the static stiffness in the main spindle interface according to variation of clamping force, rotational speed and tool holder shank. Finite element analysis is performed by using a commercial code ANSYS workbench. From the results, it has been shown that the geometry of tool holder shank is mostly influence on the variation of the static stiffness in the main spindle interface.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.8
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• pp.685-690
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• 2007

The new design of inchworm-type piezoelectric actuator is presented in this paper, Compared to conventional inchworm-type actuators, which are composed of more than three piezoelectric bodies, we can reduce the number of piezoelectric bodies by employing the proposed design, resulting in only one piezoelectric body. The overall size of the proposed actuator which consists of one piezoelectric body, two clamping parts and one extending part, is only $5{\times}6{\times}9 [mm^3]$ (DWL). The actuating characteristics of fabricated Monolithic Inchworm Type Actuator(MITA), were found to be a displacement of $0.3{\mu}m$, a generating force of 0.6N and an electric power of 0.5W.