• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.671-677
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• 1996

This paper proposes a study on the effects of motion errors for acceleration/ deceleration types. The proposed motion errors are consisted of two errors : one due to transient response of servomechanism and the other due to gain mismatching of positioning servo motor. They are derived from using laplace transformation for the block diagram of general purpose feed drive system. In order to minimize them, the paper proposes second order polynomial regression model by using orthogonal array method which describes one of experimental methodolgies. The validity and reliability of the study was veri lied on a vertical machining center equipped with FANUC 0MC through a series of experiments and analyses.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.43-45
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• 1994

This paper proposes the new method to calculate the static thrust and normal force of a hybrid type double-sided linear pulse motor by the coenergy which considered the magnetic nonlinealities. In the process of the computation, the nonlinear characteristics of the magnetic material were interpolated by the cubic spline method. And, to investigate the characteristics of the hybrid type DLPM, the static thrust and the normal force is shown as a function of displacement, input current and air airgap length. Also the simulation values are compared with the experimental ones obtained from a hybrid type DLPM.

• Journal of Advanced Marine Engineering and Technology
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• 제23권2호
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• pp.168-175
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• 1999

Unlike a general inverted pendulum system which is moved on the cart the proposed inverted pendulum system in this paper has an inverted pendulum which is moved on the two-degree-of-freedom parallelogram link. The dynamic equation of the pendulum system activated by the DD(Direct Drive)motor includes many nonlinear terms and has the high degree of freedoms. The problem is followed hat the exact mathmatical equations can not be analized by a general linear theory However the neural network trained by a simple learning method can control the dynamic system with hard nonlinearities. Learning procedure is the backpropagation algorithm with super-visory signal. The plant inputs obtained by the designed neural network in this paper can stabilize the pendu-lem and get the servo control. Experiment results have proce the effectiveness of the designed neural network controller.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 춘계학술대회 논문집(한국공작기계학회)
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• pp.399-404
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• 2001

In CNC machining, a 3D(3-dimension) linear segment and a 2D(2-dimension) circular arc are general forms given by CAD/CAM system. Generally, the 2D circular arc machining is processed using dividing into some linear segments. A 3D circular arc also don't exist in the standard form of NC data. This paper present a algorithm and method for real-time machining of a circular arc(not only the 2D one, but also the 3D one). The 3D circular arc machining is based on the 2D circular arc machining. It only needs making a new coordinate system, converting given 3D points(a start point, a end point, and a center point of a 3D circular arc) into points of the new coordinate system, and processing a inverse transformation about a interpolated point. The proposed algorithm was implemented and simulated on PC system. It was confirmed to give a gcod result.

• 한국광학회지
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• 제30권6호
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• pp.243-248
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• 2019

기관지는 호흡과정에 있어서 호흡기 시스템의 필수적인 부분이다. 그러나 기관에 협착이 발생하면 기관지 안쪽이 좁아져 호흡을 원활하게 유지하는데 문제가 되기 때문에 조기에 진단 및 치료를 함으로써 증상의 악화를 예방하는 것이 중요하다. 천식은 기도 협착의 가역적 원인의 전형적인 예이며, 급성 악화로 고통받는 환자의 수는 꾸준히 증가하고 있다. 고해상도의 광 결맞음 단층촬영법(optical coherence tomography, OCT)은 조직의 미세 구조를 관찰하는 데 적합하다. 본 연구에서는 내시경 광 결맞음 단층촬영법을 개발하였다. 1,300 nm 광 결맞음 단층촬영법과 고속으로 회전할 수 있는 서보모터를 결합하였다. 모터를 이용하여 360도 회전하면서 이미징하는 동안 프로그램으로 조작이 가능한 선형 스테이지를 사용하여 내시경 프로브를 풀백했다. 모터는 토크, 회전 속도 및 풀리의 기어비와 같은 다양한 요구사항을 고려하여 선정하였다. 샘플로는 생체 외토끼 기도 모델을 사용하였고, 샘플과 카테터는 모터 회전에 의해 흔들리지 않도록 아크릴 구조물로 고정시켰다. 광 결맞음 단층촬영 이미지는 점막 및 점막하층 구조에 대한 정보를 제공하며, 정상부분과 협착부분의 차이를 영상에서 확인할 수 있었다. 또한, 3차원 영상 복원 과정을 통해, 단면 영상과 더불어 3차원 영상에서도 기도의 협착을 식별할 수 있었다. 이 연구는 기도 협착증 진단에 도움을 줄 수 있는 영상법 개발 뿐만아니라 3차원 영상을 구현했다는 점에서 의미가 있다.

• 천문학회지
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• 제51권6호
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• pp.207-214
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• 2018

A coelostat is often used for solar observations, because it corrects the image rotation automatically by guiding sunlight into a fixed telescope with two plane mirrors. For the purposes of education and spectroscopic observation, the solar group at Seoul National University (SNU) plans to develop the SNU coelostat (SNUC) and install it in the SNU Astronomical Observatory (SAO). Requirements of the SNUC are < 1" positioning accuracy with 30 cm beam size on the entrance pupil in the compact dome. To allow for installation in the small dome, we design a compact slope type coelostat with a 45 cm primary plane mirror and a 39 cm secondary plane mirror. The motion of the SNUC is minimized by fixing the position of the slope frame. Numerical simulations of the available observational time of the designed coelostat shows that the sun can be observed ay all times from June to early August and at least three hours in other months. Since the high accuracy driving motors installed in the SNUC can be affected by external environment factors such as humidity and temperature variations, we design a prototype to test the significance of these effects. The prototype consists of a 20 cm primary plane mirror, a 1 m slope rail, a direct drive motor, a ballscrew, a linear motion guide, an AC servo motor, a reduction gear and a linear encoder. We plan to control and test the accuracy of the prototype with varying atmospheric conditions in early 2019. After testing the prototype, the SNUC will be manufactured and installed in SAO by 2020.

• 대한의용생체공학회:의공학회지
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• 제36권4호
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• pp.115-122
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• 2015

A standard air flow generator system was developed to generate air flows of various levels simultaneously applied to two different air flow transducer modules. Axes of two identical standard syringes for spirometer calibration were connected with each other and driven by a servo-motor. Linear displacement transducer was also connected to the syringe axis to accurately acquire the volume change signal. The user can select either sinusoidal or square waveform of volume change and manually input any volume as well as maximal flow rate levels ranging 0~3 l and 0~15 l/s, respectively. Various volume and flow levels were input to operate the system, then the volume signal was acquired followed by numerical differentiation to obtain the air flow signal. The measured volumes and maximal air flow rates were compared with the user input data. The relative errors between the user-input and the measured stroke volumes were all within 0.5%, demonstrating very accurate driving of the system. In case of the maximal flow rate, relatively large error was observed when the syringe was driven very fast within a very short time duration. However, except for these few data, most measured flow rates revealed relative errors of approximately 2%. When the measure and user-input stroke volume and maximal flow rate data were analyzed by linear regression analysis, respectively, the correlation coefficients were satisfactorily higher than 0.99 (p < 0.0001). These results demonstrate that the servo-motor controls the syringes with enough accuracy to generate standard air flows. Therefore, the present system would be very much practical for calibration process as well as performance evaluation and comparison of two different air flow transducer modules.

• 한국정밀공학회지
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• 제26권9호
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• pp.72-80
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• 2009

When the magnet wheel rotates over a conducting plate, it generates the traction torque as well as the repulsive force on the conducting plate. Partially-cut traction torque results in the linear force into the tangential direction. To cut the traction torque, the concept of magnetic shield is introduced. The direction change of the linear force is realized varying the shielded area of magnetic field. That is, the tangential direction of non-shielded open area becomes the direction of the linear thrust force. Specially a shape of permanent magnets composing the magnet wheel leads to various pattern of magnetic forces. So, to enlarge the resulting force density and compensate its servo property a few simulations are performed under various conditions such as repeated pattern, pole number, radial width of permanent magnets, including shape of open area. The theoretical model of the magnet wheel is derived using air-gap field analysis of linear induction motor, compared with test result and the sensitivity analysis for its parameter change is performed using common tool; MAXWELL. Using two-axial wheel set-up, the tracking motion is tested for a copper plate with its normal motion constrained and its result is given. In conclusion, it is estimated that the magnet wheel using partial shield can be applied to a noncontact conveyance of the conducting plate.

• 전자공학회논문지T
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• 제35T권1호
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• pp.82-89
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• 1998

PI제어기는 서보시스템에 널리 사용되어 왔다. 그러나 PI제어기로 설계된 시스템응답은 부하변동과 같은 외란이나 시스템 변수의 변화에 대하여 원하는 시간응답을 보존할 수가 없다. 따라서 시간응답 특성의 견실성을 확보하면서, 구현상의 어려움을 해결하기 위하여 선형요소만으로 구성되는 선형 모델추종제어(LMFC: linear model following control) 방법이 있다. 이 방법은 기준모델의 출력을 플랜트가 추종하도록 제어하는 것으로, 플랜트의 구조적 섭동에 무관한 시간응답 특성을 얻을 수 있으나 부하토크에 대한 응답속도가 느린 단점이 있다. 이러한 단점을 해결하기 위하여 모델추종제어기에 강인성향상기를 보조모델을 사용하여 도입함으로써 지주파 부하토크에 대한 응답속도를 향상시켰다. 제안된 제어기(RMFC: LMFC with robust enhancer)는 저주파 부하토크에 대하여 LMFC보다 강인한 특성을 보였으며 시뮬레이션 및 TMS320C30 DSP 시스템에 의한 실험으로 검증하였다.

• Journal of Electrical Engineering and Technology
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• 제9권2호
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• pp.514-522
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• 2014

A new type of high precision electromagnetic suspension (EMS) which can support heavy tray along long stroke rail is proposed in this paper. Compared with the conventional EMS, the suggested moving-core typed EMS has the levitation electromagnets (EMs) on the fixed rail. This scheme has high load capability caused by iron-core and enables simple tray structure. Also it does not have precision degradation caused by heat generation from EMs, which is a drawback of conventional EMS. With these merits, the proposed EMS can be an optimal contactless linear bearing in next generation flat panel display (FPD) manufacturing process if the ability of long stroke movement is proved. So a special Section Switching Algorithm (SSA) is derived from the resultant force and moment equations of the levitated tray which enables long stroke movement of the tray. In order to verify the feasibility of the suggested SSA, a simple test-setup of the EMS with 2 Section-changes is made up and servo-controlled in the simulation and experiment. The simulation shows the perfect changeover the EMs, and the experiment shows overall control performance of under ${\pm}40{\mu}m$ gap deviations. These results reveal that the newly suggested contactless linear bearing can simultaneously achieve high load capability and precision gap control as well as long stroke.