• Journal of the Korean Society for Precision Engineering
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• v.17 no.3
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• pp.158-164
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• 2000

In recent year, desire and request fer micro automation are growing rapidly covering the whole range of the industry. This has been caused mainly by request of more accurate manufacturing process due to a higher density of integrated circuits in semiconductor industry. This paper presents a six d.o.f fine motion stage using magnetic levitation technique, which is one of actuating techniques that have the potential for achieving such a micro motion. There is no limit in motion resolution theoretically that the magnetically levitated part over a fixed stator can realize. In addition, it Is possible to manipulate the position and the force of the moving part at the same time. Then, the magnetic levitation technique is chosen into the actuating method. However, we discuss issues of design, kinematics, dynamics, and control of the proposed system. And a few experimental results fur step input are given.

• Journal of Engineering Education Research
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• v.15 no.5
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• pp.87-92
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• 2012

Independent study is a major ability of engineering students. In independent study training practice, we need to use different instructional strategies and responds to individual student needs and learning styles. The purpose of this paper is to demonstrate a four-step student independent study training mode we applied to teaching the Biomedical Engineering students in Dali University, China. We developed this teaching mode to fulfill the goals of the first years' undergraduates training and improve the students learning skills. The four-step teaching mode includes both in-class and out-of-class activities. The emphasis is on how to train students to get information from the reading materials, understand the concept, develop critical thinking and eventually become independent learner.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.376-377
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• 2006

Chemical Mechanical Planarization (CMP) has emerged as an enabling technology for the manufacturing of multi-level metal interconnects used in high-density Integrated Circuits (IC). Recently, multi-level structures have been also widely used m the MEMS device such as micro engines, pressure sensors, micromechanical fluid pumps, micro mirrors and micro lenses. Especially, among the thin films available in IC technologies, polysilicon has probably found the widest range of uses in silicon technology based MEMS. This paper presents the characteristic of polysilicon CMP for multi-level MEMS structures. Two-step CMP process verifies that is possible to decrease dishing amount with two type of slurries characteristics. This approach is attractive because two-step CMP process can be decreased dishing amount considerably more then just one CMP process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.264-270
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• 1996

In this paper, a computer automated system has been developed for measuring the focal length of camera lens using the MTF(Modurar Transfer Function) based on the signal processing around a line CCD and autocollimator. An optical Path for the focal length measurement system has been designed around thelight sourec, collimator, camera, mirror and the line CCD. The eyepiece of the collimator is replaced byline CCD, and the mirror is moved along the focal axis by a PC driven step motor. An efficient method has been designed for finding the optimum MTF value for the focal length based on the least squares approach. The developed system is fullycomputer automated: signal transmission to and from the camera, MTF evaluation based on the line CCD, step motor contorl, etc. The developed system has been applied to a practical camera manufacturing process and demonstrated its performance

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.903-906
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• 1997

For the net shape manufacturing, grinding is a important process that influences directly the accuracy and the integrity of products. We studied and researched the grinding force, surface roughness, and grinding wheel durability, according to the change of a feed speed of the table and a depth of the cut step by step with experiment that it is used to WA wheel. Workpiece materials were used STDII. The purpose of this study proposes the basic data for design of the machine tool and for controlling the machining parameters to obtain optimum performance of plunge grinding system during operation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.442-445
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• 1997

A challenging activity in the manufacturing industry is to perform in real time the continuous monitoring of the process state, the situation assessment and identification of the problem on line and diagnosis of the cause and importance of the problem if he process does not work properly. This paper describes LAT(Ladder Analysis Tool) system for fault tree generation to improving the fault diagnosis of CNC machine tools. The system consists of 4 steps which can automatically ladder analysis from ladder diagram to two diagnosis function models. The two diagnostic models based on he ladder diagram is switching function model and step switching function model. This system tries to overcome diagnosis deficiencies present machine tool.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.215-222
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• 2003

The new square electro-magnetic chuck, which is using for the clamping devices on a grinding machine, is developed in this study to improve the convenience of grinding works. The various kinds of structures are recommended to find the most adequate magnetic characteristics through the analytical approach using finite element methods. The analyzed results are retrofitted to solve the drawbacks of previous models step by step by considering the magnetic fields, strength and distribution of drag force, and thermal deformations of chuck. such as high parallelism and flatness. Finally the best recommended models is designed to satisfy the KS specifications required for the commercial magnetic chuck. The prototype chuck with this dimensions and structures is manufactured. For this final model, the experimental verifications are investigated whether the KS specifications are satisfied.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.224-225
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• 2000

Transparent and hard materials such as sapphire are used for many industrial applications as optical windows, hard materials on mechanical contact against abrasion, and substrate materials for opto-electronic semiconductor devices such as blue LED and blue LD etc. The materials should be cut along the proper shapes possible to be used for each application. In case of blue LED, the blue LED wafer should be cut to thousands of blue LED pieces at the final stage of the manufacturing process. The process of cutting the wafer is usually divided into two steps. The wafer is scribed along the proper shapes in the first step. It is inserted between transparent flexible sheets for easy handling. And then, it is broken and split in the next step. Harder materials such as diamonds are usually used to scribe the wafer, while it has a problem of low depth of scribing and abrasion of the harder material itself. The low depth of scribing can induce failure in breaking the wafer along the scribed line. It was also known that the expensive diamond tip should be replaced frequently for the abrasion. (omitted)

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.2
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• pp.115-123
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• 2000

We propose an extended version of multi-step algorithm of self-calibration of interferometric optical testing instruments. The key idea is to take wavefront measurements with near equal steps in that a slight angular offset is intentionally provided in part rotation. This generalized algorithm adopts least squares technique to determine the true azimuthal positions of part rotation and consequently eliminates calibration errors caused by rotation inaccuracy. In addition, the required numbers of part rotation is greatly reduced when higher order spatial frequency terms are of particular importance.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.826-830
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• 2000

Sculptured surface machining plays a vital role in the process of bring new Products to the market place. A great variety of products rely on this technology for the production of the dies and moulds used in manufacturing. And, the use or CNC machines and CAD/CAM system has become a vital parts or product development process. But, cusp is inevitable by-product in sculptured surface machining, and it is very difficult to calculate the cusp height correctly. In this study, an analytical cusp height model is proposed considering the radius of the ball end mill, radius of machined workpiece and the inclined angle of convex or concave circular surface. Experiments were performed to check the validity of this proposed model and experimental results showed that the proposed cusp model were very effective.