• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.6
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• pp.43-50
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• 2000

Design and experiments of a nondestructive testing system with a solenoid eddy current sensor to inspect deterioration of ASCR-OC (ACSR Outdoor Cross-linked Polyethylene Insulated Wires) usually used in HV overhead distribution lines in domestic areas in presented in this paper. Through corrosion mechanisms and deterioration results for ACSR-OC conductors are examined, it is shown that corrosion may lead to the reduction of the effective cross section area of conductors is proposed. The measurement system consisting of a constant current source with a RF frequency, a signal processing unit and a motor driver/ controller is designed and implemented. This instrument has such capabilities as detecting the sensor output and estimating diameter change of the testing conductors, continuously. As a result, it was verified that such corrosion detector system with an eddy current sensor can be shown good effectiveness for estimating the serious faults due to deterioration in overhead distribution lines and giving an early warming before severe aged conductor may lead to fail.

• The Magazine of the IEIE
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• v.24 no.10
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• pp.23-44
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• 1997

이 글에서는 요즘 신문이나 텔레비전을 통해서 인체 내부를 돌며 검사 및 치료를 하는 마이크로 로보트 등의 차세대 첨단기술로서 일반 국민들에게 소개되기도 하며, MEMS, 마이크로머신, 마이크로시스템, 혹은 초소형 정밀기계 등으로 불리는 기술과 이 기술에 대한 각국 (미국, 일본, 유럽, 한국)의 기술 동향을 소개한다. 이에 이어서, 현재 과기처의 선도기술개발사업 (소위 G7사업) 으로서 진행되고 있는 초소형 정밀기계 기술개발 사업에 대한 소개를 한다. 이 분야에 종사하지 않는 보통 사람들을 위해 가급적 쉬운 말로 풀어 쓰도록 노력하였다. 이 글에서 다루고 있는 크기의 기본 단위는 마이크로미터 (천분의 일 밀리미터) 이며, 사람의 머리카락의 직경이 약 100 마이크로미터 (0.1mm) 내외이다. 초소형 기계나 초소형 부품들은 대개 이 머리카락의 직경정도이며, 머리카락속에 모터나 기어 등이 들어있다고 생각해도 크게 틀리지 않을 것이다.

• Journal of the Korea Society of Computer and Information
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• v.8 no.4
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• pp.75-80
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• 2003

In this paper, we designed add current scan system basically. Although NDT system using AC method in now days had problem with limit of detection rate and limit of device organization, in this paper, we made up these problem so that designed device smaller than system used, reduction of cost of system organization and precision of measuring crack. Also, AC leakage flux system had high accuracy about minute crack in the surface and advantage of designing system easily so that we designed system for concerning about crack of surface. Furthermore, it can be able to detect exact crack of reference in wide area by using DSP320C31 chip to reduce the time of measuring crack.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.2
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• pp.27-32
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• 2001

In this paper, the three dimension scanner system employing the parallel camera model is discussed. The camera calibration process and the three dimension scanning algorithm are developed. The laser strip line is utilized for assisting stereo matching. An object being scanned rotates on the plate which is activated by a stepping motor, The world coordinate which is. the measured distance from the camera to the object is converted into the model coordinate. The facets created from the point. cloud of the model coordinate is used for rendering the scanned model by using the graphic library such as OpenGL. The unmatched points having no validate matching points are interpolated from the validate matching points of the vicinity epipolar lines.

• Journal of Aerospace System Engineering
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• v.11 no.5
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• pp.42-49
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• 2017

The solid rocket motor(SRM) consists of a motor case, igniter, propellants, nozzle, insulation, controller, and driving device. The liquid rocket propulsion systems(LRPSs) cools the nozzle by the fuel and oxidizer but SRM does not cool the nozzle. The nozzle of SRM is high temperature condition and high velocity condition so occurs the erosion by combustion gas. This erosion occurs the change of nozzle throat and reduces thrust performance of rocket. The material of Rocket nozzle is minimization of erosion and insulation effect and endure the shear force, high temperature and high pressure. The purpose of this study is to investigate the erosion characteristics of solid rocket nozzles by each combustion time. Through the structure inspection of Graphite and C-C composite, identify the characteristics of the microstructure before and after erosion.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.6
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• pp.525-532
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• 2017

The development of an inkjet-based manufacturing machine for the production of next-generation displays using organic and quantum-dot light emitting diodes at a low cost has been conducted. To employ inkjet printing in production lines of displays, the development of a high-speed inkjet-monitoring device to verify the reliable droplet jetting status from multiple nozzles is required. In this study, an inkjet monitoring device using a rotatable mirror with rotary and linear ultrasonic motors is developed in place of a conventional, linear reciprocating, motion-based inkjet monitoring device. Its performance is also demonstrated. The measurements of circular patterns with diameters of $10{\mu}m$, $30{\mu}m$, and $50{\mu}m$ are performed with the accuracies of $0.5{\pm}1.0{\mu}m$, $-1.2{\pm}0.3{\mu}m$, and $0.2{\pm}0.5{\mu}m$, respectively, within 17 sec. By optimizing the control program, the takt time can be reduced to as short as 8.6 sec.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.5
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• pp.471-478
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• 2010

Thin films play an important role in many technological applications including microelectronic devices, magnetic storage media, MEMS and surface coatings. It is well known that a thin film's material properties can be very different from the corresponding bulk properties and thus there has been a strong need for the development of a reliable test method to measure the mechanical properties of a thin film. We have developed an alternative and convenient test method to overcome the limitations of previous membrane deflection experiment and uniaxial tensile test by adopting a white light interferometer having sub-nanometer out-of-plane displacement resolution. The freestanding aluminium specimens are tested to verity the effectiveness of the test method developed and get the tensile properties. The specimens are 0.5 rum wide, $1{\mu}m$ thick and fabricated through MEMS processes including sputtering. 1 to 5 specimens are fabricated on Si dies. The membrane deflection experiments are carried out by using a homemade tester consisted of a motor-driven loading tip, a load cell, and 6 DOF alignment stages. The test system is compact enough to set it up beneath a commercial white light interferometric microscope. The white light fringes are utilized to align a specimen with the tester. The Young's modulus and yield point stress of the aluminium film are 62 GPa and 247 MPa, respectively.