• 한국정밀공학회지
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• 제12권8호
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• pp.131-139
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• 1995

In this study, small size stacker Crane for automatic ware house and interface circuit is designed and manufactured. IBM-PC is used as a controller. At 50kg$_{f}$ load, optimal motion velocity is 20 mm/min for X and Y axis and 12 mm/min for Z axis. Position fesolution is 0.005 mm and repeatability is .+-. 0.025 mm. Through characteristic experiment, effectiveness of the designed and manufactured stacker crane. PC control program, and design of interface circuit and construction of control system are shown. From these results, the developed stacker crane can be apply to FMS(Flexible Manufacturing System) and FA(Factory Automation) of industrial field.d.

• 대한핵의학회지
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• 제38권4호
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• pp.275-281
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• 2004

Compared with the earlier technique of dual photon absorptiometry (DPA) using $^{153}Gd$ radionuclide source, dual energy X-ray absorptiometry (DXA) has advantages of higher precision, accuracy and shorter scanning time. Despite the change from DPA to DPX, the nuclear medicine physicians has remained one of major suplier of this service due to long-standing use of DPA. Among many kinds of bone densitometries, DXA is the "gold standard" for the noninvasive diagnosis of osteoporosis. Especially there is no role for peripheral devices in the monitoring of patients on therapy. But, there are some areas of controversy related to the application of DXA, such as proper site of measurement, accurate interpritation, appropriate use of T-score, and the reference population young database. And the accuracy, precision, and quality control issues relating to bone density measurement are important subjects. To address these issues, the International Society for Clinical Densitometry (ISCD) has convened two Position Development Conferences and addressed official positions. This review deals the key elements of ISCD position paper and other important issues on the management of bone densitometry.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.580-583
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• 2002

This paper presents a novel pose description corresponding to the structure characteristics of parallel manipulators, which is convenient and intuitionistic to us. A class of 3-RSR parallel manipulator is considered here. Through analysis on geometry theory, we obtain a new method of the closed-form solution to the forward kinematics. The closed-form solution contains two different meanings-analytical and real-time. So we reach the goal of practical application and control. A numerical example is also presented and are verified by an inverse kinematics analysis. It shows that the method has a practical value for real-time control.

• 한국세라믹학회지
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• 제40권10호
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• pp.981-984
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• 2003

본 논문에서는 고정민 위치제어가 가능한 선형초음과 모터를 설계 및 제작하였다. 제안된 선형 초음파 모터의 발파장 진동자에 진계(Usinwt, Ucoswt)를 인가했을때 진동법의 불출부에서 발생하는 타원궤직은 이동자를 구동시킨다. 제작된 선형 초음파 모터의 면위궤적은 시뮬레이션 결과와 일치했으며, 압차력이 50 N일 때 이동자에서 발생하는 최대 힘은 9 N, 최대속도는 0.9 ㎧이고 20 N일 때 최대 힘은 2.4 N, 최대 속도는 0.38 ㎧의 특성을 나타냈다.

• 한국정밀공학회지
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• 제20권10호
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• pp.82-88
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• 2003

Many visual servoing algorithms have been recently developed by the robot vision researchers. They do not, however, consider the stability of servoing system. The camera calibration is the most important factor to the control stability and performance of position based visual servoing. In this article we describe the ECL(End Point Closed Loop) servoing can make no steady state error for the control of 6-DOF robot of which accuracy is dependent on the camera calibration and kinematics. And we propose a dynamic calibration algorithm, which can improve stability and performance of ECL visual servoing. To verify the potential of our approach, we run assembly experiments and present our finding.

• 한국정밀공학회지
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• 제22권6호
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• pp.118-126
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• 2005

There are many types of walking robots in the world. For dynamic walking of the robots it is necessary to keep its dynamic stability. The dynamic stability is influenced by the position of ZMP (zero moment point). In this paper we study the control of the ZMP position of walking robot. For experiment we developed a quadruped robot and analyzed the dynamic stability of the robot. Developed robot has 2 joints at each leg and WBO (weight balancing oscillator) on the body of the robot. The WBO is designed to move linearly from side to side when the robot walks dynamically. Walking test was performed to verify the validity of the proposed methods. Especially we showed that the dynamic stability of the robot can be improved without sacrifice of the walking speed by control the WBO.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.248-252
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• 2002

In this study, a synchronous controller which can be applied to two-axes position synchronization has been developed. The synchronous control system based on coupling structure has been composed of speed and synchronous controller. The speed controller has been designed to fellow speed reference. And the synchronous controller has been designed in the view point of accurate synchronization and robust stability by $H_{\infty}$ approach. The effectiveness of the designed synchronous controller has been demonstrated by experiment.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.1961-1965
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• 1991

This paper deals with an automatic and precision alignment technique for proximity printing in x-ray lithography, using two pairs of moire gratings, with moire signals from each pair being 180.deg. out of phase with each other. We constructed an automatic and precision alignment experimental system which could measure both transmitted moire signals and reflected moire signals at the same time. The automatic alignment was achieved using transmitted moire signals and also reflected moire signals as a control signal for a stage driver. The alignment position of the system was monitored not only by a control signal but also by a non-control signal. The effect of transmitted and reflected moire signals upon alignment accuracy was discussed. We concluded that the technique using diffracted moire signals is a viable automatic and precision alignment technique.

• International Journal of Precision Engineering and Manufacturing
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• 제3권4호
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• pp.43-53
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• 2002

Polishing a die that has free-form surfaces is a time-consuming and tedious job, and requires a considerable amount of high-precision skill. In order to reduce the polishing time and cope with the shortage of skilled workers, a user-friendly automatic polishing system was developed. The polishing system is composed of two subsystems, a three-axis machining center and a two-axis polishing robot. The system has five degrees of freedom and is able to keep the polishing tool in a position normal to the die surface during operation. A sliding mode control algorithm with velocity compensation was proposed to reduce tracking errors. Trajectory tracking experiments showed that the tracking error can be reduced prominently by the proposed sliding mode control compared to a PD (proportional derivative) control. To evaluate the polishing performance of the polishing system and to and the optimal polishing conditions, the polishing experiments were conducted.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.798-800
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• 2001

Precision control technologies are required for photolithography. The linear BLDC motor is used for the stage operations. The stage that is installed in a photolithography device is basically controlled in three directions(x, y, z axes). This paper presents precision control technologies of the linear BLDC motor in one direction by computer simulations. A position control system with linear BLDC motor is now being tested.