• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.917-923
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• 2001

This paper presents the fabrication and testing results of a dual stage microactuator system for fine positioning of magnetic heads in hard disk drives. An electrostatic rotary microactuator was newly designed and fabricated. The microactuator was integrated into the head gimbal assembly of a disk drive system and its dynamic characteristics were investigated. Experimental results show that natural frequency and voltage gain of the microactuator are 4.3 KHz and 25 nm/V and the dual stage microactuator system achieves the tracking accuracy of 30 nm.

• Journal of the Semiconductor & Display Technology
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• v.2 no.2
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• pp.31-37
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• 2003

This paper presents a measurement system of mechanical property using dual servo system. There are many kinds of method to measure material properties such as tensile test, indention and bending test. It is highly required to measure the properties of nano-sized material and structure. However, It is need more accurate measurement system, more stable and frequency response than conventional test. In this paper, we designed the dual servo system for a measuring instrument The dual servo system consisting of a coarse stage and a fine motion stage with VCM and PZT is proposed. Mechanical mechanism is designed with the leaf spring type of flexure hinge joint. Lead compensator is applied to this control system, and is designed by PQ method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.3C
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• pp.368-373
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• 2004

Extremely fine tine resolution of ultra-wideband (UWB) signal poses a new problems to the system designer. A reasonable accuracy of the system clock is necessary to process signals with such a high space resolution. A useful way of illustrating the time resolution of a signal is to evaluate the ambiguity function. The ambiguity function for carrierless UWB defined using the time mismatch and time scaling factor as its two parameters. The UWB ambiguity function is evaluated for various signaling schemes of impulse radio.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.251-255
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• 1995

정밀위치결정 기구는 정밀가공기, 계측기기, 반도체 제조장치등의 각종산업기기에 있어 중요 장치로 많이 이용되고 있다. 반도체 회로의 고정밀화, 고집적화, 가공기의 고정도화와 함께 위치결정기구의 기술은 매년 엄격해지고 있다. 현재는 0.1 -0.01 .$\mu$ m의 정도가 요구되고 있어 이에 대응할 수 있는 고정밀 미동제어 위치결정 제어에 대한 연구가 활발히 진행되고 있다. 또한 고정도와 함께 대스트로크(Stroke)를 가지며, 동시에 고속동작의 실현이필요하다. 따라서 이런 여러 성능을 만족시키는 것은 고부가가치 산업에 있어 매우 중요한 조건 중의 하나이다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.4 no.3
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• pp.316-321
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• 2004

In this paper, we have developed a new mounting head system for flip chip. The proposed head system consists of a macro/micro positioning actuator for stable force control. The macro actuator provides the system with a gross motion while the micro device yields fine tuned motion to reduce the harmful impact force that occurs between very small sized electronic parts and the surface of a PCB(printed circuit board). In order to show the effectiveness of the proposed macro/micro chip mounting system, we compared the proposed system with the conventional chip mounting head equipped with a macro actuator only. A series of experiments were executed under the mounting conditions such as various access velocities and PCB stiffness. As a result of this study, a satisfactory voice coil actuator as the micro actuator has been developed, and its performance meet well the specifications desired for the design of the chip mounting head system and show good correspondence between theoretical analysis and experimental results.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.37-39
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• 1998

The hybrid step motor has found applications in a wide range of mechanical systems as a low cost, open-loop positioning device. The step motor provides good stiffness at rest against disturbing load influences, a combination of moderate speed fine resolution, high reliability and simplicity. In recent years, considerable competition has arisen over the technological issue of wheather the device should be applied as a 2-Phase or 5-Phase machine. In this paper, to compare two systems, we have atempted to derive the mathematical. model, and analysed operating detent torque with this model. The analysis shows that a fundamental component of the permeance distribution produces the average torque and that harmonic components produce the ripple torque.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.382-387
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• 1992

In order to obtain desired arc welding performance, we already developed an arc welding robot system that enabled coordinated motions of dual arm robots. In this system one robot arm holds a welding target as a positioning device, and the other robot moves the welding torch. Concerning to such a dual arm robot system, the positioning accuracy of robots is one important problem, since nowadays conventional industrial robots unfortunately don't have enough absolute accuracy in position. In order to cope with this problem, our robot system employed teaching playback method, where absolute error are compensated by the operator's visual feedback. Due to this system, an ideal arc welding considering the posture of the welding target and the directions of the gravity has become possible. Another problem still remains, while we developed an original teaching method of the dual arm robots with coordinated motions. The problem is that manual teaching tasks are still tedious since they need fine movements with intensive attentions. Therefore, we developed a 3-dimensional vision guided robot control method for our welding robot system with coordinated motions. In this paper we show our 3-dimensional vision sensor to guide our arc welding robot system with coordinated motions. A sensing device is compactly designed and is mounted on the tip of the arc welding robot. The sensor detects the 3-dimensional shape of groove on the target work which needs to be weld. And the welding robot is controlled to trace the grooves with accuracy. The principle of the 3-dimensional measurement is depend on the slit-ray projection method. In order to realize a slit-ray projection method, two laser slit-ray projectors and one CCD TV camera are compactly mounted. Tactful image processing enabled 3-dimensional data processing without suffering from disturbance lights. The 3-dimensional information of the target groove is combined with the rough teaching data they are given by the operator in advance. Therefore, the teaching tasks are simplified

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.4
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• pp.683-690
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• 2018

In this paper, a new signal processing technique is proposed for calibrating gain, phase, delay offsets in array antenna based anti-jamming minimum variance distortionless response (MVDR) global-positioning-system (GPS) receivers. The proposed technique estimates gain, phase and delay offsets across the antennas, and compensates for the offsets based on the estimates. A pilot signal with good correlation characteristics is used for accurate estimation of the gain, phase and delay offsets. Based on the cross-correlation, the delay offset is first estimated and then gain/phase offsets are estimated. For fine delay offset estimation and compensation, an interpolation technique is used, and specifically, the discrete Fourier transform (DFT) is employed for the interpolation technique to reduce the computational complexity. The proposed technique is verified through computer simulation using MATLAB. According to the simulation results, the proposed technique can reduce the gain, phaes and delay offset to 0.01 dB, 0.05 degree, and 0.5 ns, respectively.

• Korean Journal of Poultry Science
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• v.23 no.1
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• pp.9-17
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• 1996

This study was conducted to compare the survival rate of chick embryos among different eggshell window positions and to search for the most appropriate injection position. The eggshells were punctured at blunt-end, sharp-end and side-up with a sterilized fine forceps, respectively. The survival rate of sharp-end window was higher than the other window positions. Injection of Dulbecco’s modified eagle’s medium (DMEM) through blunt-end window (BE1) was impossible because inner cell membrane was obscure. The 2 ${\mu}$L DMEM was injected into 2.5 d-old embryo blood vessel through sharp end window. To prevent hemorrhages at the point of injection, the air bubbles were injected into the embryo blood vessel. The survival rate of chicks embryo in sharp end window was about 17.0％. Therefore, this sharp-end window system will be helpful for the production of germline chimera or transgenic chicken using primordial germ cells ( PGCs ).

• Journal of Advanced Navigation Technology
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• v.14 no.2
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• pp.151-160
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• 2010

For the realization of future intelligent transportation systems, fine-grained lane-by-lane traffic monitoring and control functionalities are among the most important technology barriers to overcome. To satisfy the accuracy requirement for traffic monitoring, a GNSS receiver network is designed. The designed receiver network consists of three different types of entities; reference server, broadcaster, and client. For deployment flexibility, all the entities utilize the international message standard RTCM SC-104 version 3.0. For fine-grained traffic monitoring, the client is designed to utilize position-domain carrier-smoothed-code filters to provide accurate vehicle coordinates in spite of frequent addages and outages of visible satellites. An experiment result is presented to evaluate the positioning accuracy of the proposed method.