• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2005년도 한국우주과학회보 제14권1호
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• pp.138-142
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• 2005

위성자세제어용 구동기 인 반작용 휠은 축 방향 토크뿐만 아니 라 횡 축 방향 외 란 토크와 힘을 발생시켜 위성의 정밀 지향 안정성에 영향을 미치게 된다. 이를 위해서는 반작용 휠 구동시의 발생 외란을 정밀하게 측정할 필요가 있다. 그러나 반작용 휠의 구동은 측정테이블의 진동을 야기 시키고 테이블의 공진 주파수 영역에서 큰 측정 오차를 유발한다. 본 논문은 이러한 진동오차들을 줄이기 위하여 주파수 보정법에 의한 사후처리 과정을 제시하고, 이 보정법으로 얻어진 데이터들로부터 외란 파라미터를 결정함으로써 구동기 외란의 보다 정밀한 측정을 가능케 하기 위함이다. 이 보정법을 적용함으로써 구동기 외란 측정 주파수범위를 넓힐 수 있다.

• 한국산업융합학회 논문집
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• 제21권1호
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• pp.37-44
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• 2018

In this work, a 4-DOF industrial robot system with three translational and one rotational motions which is widely used in palletizing applications is developed. In order for small robot manufacturing companies to develop their own robot systems for CNC machining and/or general automations, the analysis and design methods of a 4-DOF robot manipulator are presented and the development of a PC-based robot controller with EtherCAT are introduced. It is noted that the robot controller is developed by using Simulink Real-Time, which can provide an integrated environment of easier control algorithm development and data logging. Through position control and accuracy/repeatability measurement results, the developed robot prototype has comparable performances with commercial counterparts. In the future works, the advanced functions of industrial robots such as kinematic calibration, vibration suppression control, computed torque control, etc. will be investigated.

• 한국정밀공학회지
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• 제23권6호
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• pp.57-63
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• 2006

Gravitational centers of precise spinning components must coincide with the rotational centers of those to reduce noise and vibration and to extend those lift as well. Therefore quality control should be performed in the manufacturing process, in which the unbalance moments are accurately measured. In this paper 3-point weighing method is adopted to measure the unbalance moment of small-sized precision spinning elements using electronic scales with 0.1 mg resolution. Firstly methods to eliminate the fixture error and to reduce the effects of frictional force that is known as side effect, are proposed. A measuring system is developed and various experiments are performed to verify the proposed approach. The measured and calculated values are analysed in statistical methods, and this provides the errors of the measuring system. The results show that the proposed theory and test procedures gives reliable unbalance moments and gravitational centers.

• 대한기계학회논문집
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• 제19권9호
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• pp.2082-2088
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• 1995

In this paper, we designed and fabricated the magnetic bearings and built-in type cylindrical capacitive transducers for improving the vibration characteristics of rotating shaft. The eddy current and magnetic field from the electromagnet of the bearing don't affect the measuring signal of the capacitive type transducers so that it is possible to locate the capacitive sensor plates around the magnetic bearing poles and can improve the spillover problem which is induced by the noncollocation of the sensors and actuators. According to the sensitivity calibration schemes using a X-Y table, the cylindrical capacitive transducers have a good linearities in the .+-.70.mu.m range from the geometric center of the sensor plates. The measured results also show high displacement sensitivities of the sensors. According to the performance test of the magnetic bearing which is controlled by the analog PD controllers, we found that the built-in capacitive transducer system successfully measures the journal displacement in the magnetic field and therefore the magnetic bearing system supports the rotating shaft up to 12,000 rpm.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.110-113
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• 2001

We present an interferometer system, which is able to perform both the phase shifting interferometry and white light interferometry. The interferometer system uses a d.c. motor to control the probe position with an accuracy of 10nm, which shows an outstanding performance on white light interferometry. However, the moving mechanism of d.c. motor is not accurate enough for the phase shifting interferometry that requires a moving precision less than 1 nm. We therefore propose a Fourier transform technique to calculate the phase of interferograms, which is strongly resistant to calibration errors and external vibration. Experimental results show that the Fourier transform technique is capable of reducing the measurement error caused by inaccurate movement within 0.1nm.

• 한국정밀공학회지
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• 제21권10호
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• pp.154-161
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• 2004

An experimental method for measuring side-necking deformation near a crack-tip is described. It is based on Stereoscopic Digital Speckle Photography and Digital Image Correlation, and it is simple and robust to mechanical vibration inherent to a hydraulic material test system. The validity and accuracy are evaluated through a calibration fur rigid body translation. A case study has been performed for a CT specimen made of a ductile steel and the three dimensional profiles of the side-necked region are presented as the load increases. Also, the details of the procedure and the surface treatment are discussed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.591-594
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• 2000

In the recent day, fatigue life prediction techniques play a major role in the design of components in the ground vehicle industry. Full scale durability testing in the laboratory is an essential of any fatigue life evaluation of components or structure of the automotive vehicle. Component testing is particulary important in today's highly competitive industries where the design to reduce weight and production costs must be balanced with the necessity to avoid expensive service failure. Generally, 3-axis durability testing device is used to carry out the fatigue test. In this paper, The operation software for simultaneously driving 3-axis vibration testing device is developed and the displacement of the 3-axis actuator is separately calibrated by LDT Moreover, the input and output data are displayed in windows of PC controller with real time.

• Smart Structures and Systems
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• 제18권1호
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• pp.17-29
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• 2016

In this paper, the possibility of using human induced loading (HIL) to detect a decrease of tension in the cable-stays of an existing footbridge is investigated. First, a reliable finite elements model of an existing footbridge is developed by calibration with experimental data. Next, estimates of the tension in the cables are derived and their dependency on the modal features of the deck is investigated. The modelling of the HIL is briefly discussed and used to perform the nonlinear, large strain, dynamic finite elements analyses. The results of these analyses are assessed with focus on characterizing the time histories of the tension in the cables under pedestrian crossing and their effects on the deck response for different initial conditions. Finally, the control perspective is introduced in view of further research.

• Archives of Pharmacal Research
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• 제28권4호
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• pp.458-462
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• 2005

The water content of skin was determined using a FT near infrared (NIR) spectrometer. NIR diffuse reflectance spectra were collected from hairless mouse, in vitro, and from human inner arm, in vivo. It was found that the variation of NIR absorbance band 1450 nm from OH vibration of water and 1940 nm from the combination involving OH stretching and OH deformation, depending on the absolute water content of separated hairless mouse skin, in vitro, using the FT NIR spectrometer. Partial least squares regression (PLSR) was applied to develop a calibration model. The PLS model showed good correlation. For practical use of the evaluation of human skin moisture, the PLS model for human skin moisture was developed in vivo on the basis of the relative water content of stratum corneum from the conventional capacitance method. The PLS model predicted human skin moisture with a standard errors of prediction (SEP) of 3.98 at 1130-1830 nm range. These studies showed the possibility of a rapid and nondestructive skin moisture measurement using FT NIR spectrometer.

• Journal of Radiation Protection and Research
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• 제22권4호
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• pp.263-272
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• 1997

방사선 작업자의 과피폭을 방지하기 위해 방사선 작업 도중 이상 사태가 발생할 경우 광 음경보가 발생한 후 이상 사태 발생 90분, 발생 30분간의 방사선량과 방사선량율 변화를 저장하고 외부 PC로 데이터를 전송한 후 사고를 분석하여 차후에 같은 유형의 방사선 사고를 사전에 예방할 수 있도록 고안된 방사선 경보장치를 개발하였다. 이 방사선 경보장치의 특징은 넓은 방사선 측정 범위(10mR/h $\sim$ 100 R/h), 방사선 준위의 기록 및 기억, PC와의 data처리 기능, 휴대성, 교정 기능에 의한 높은 정밀도(${\pm}5%$), 인지도가 높은 강력한 경보기능 채택 등이다. 개발된 방사선 경보장치의 물리적 환경 적응시험을 가장 엄격한 ANSI N42.17A의 표준 시험조건에 의거하여 온도, 습도, 진동, 전자기파 간섭 등에 관해 한국표준과학연구원에서 수행하였으며 모든 시험항목을 통과하였다.