• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.11-15
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• 2002

This paper presents the thermal characteristic analysis of a high-speed HMC with spindle speed of 50,000rpm. The spindle is supported by two radial and axial magnetic bearings. and the built-in motor is located between the axial and rear radial magnetic bearings. The X-axis and Y-axis feeding systems are composed of linear motor and linear motion guides, and the Z-axis feeding system is composed of servo-motor, ballscrew and linear motion guide. The thermal analysis model of high-speed HMC is constructed by the finite element method, and the thermal characteristics in the design stage are estimated based on the temperature distribution and thermal deformation under the conditions related to the heat generation of built-in motor, magnetic bearings, linear motors, servo-motor, ballscrew, and so on.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.136-139
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• 2006

In this paper we propose a small form factor actuator using an inclined motion guide for auto-focusing and zoom motions for mobile information devices. The novel structure using the inclined motion guide and a lens-supporting beam converts the circular motion by an ultrasonic motor into the linear motion of the optical lens. The proposed actuator has a simple structure to minimizing the mechanical tolerance, and the stroke is easy to modify by controlling the inclined angle. Experiments using a prototype verify the validity of the model as small form factor optical actuator.

• Current Optics and Photonics
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• 제1권2호
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• pp.101-106
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• 2017

Optical structures of a tapered ultra-thin light guide film (LGF) were optimized by optical simulation for increasing coupling efficiency between light sources and the LGF. A serration pattern on the entrance side surface could provide a comparable coupling efficiency to that of the conventional LGF where a linear, asymmetric prism array was formed on the taper surface. Several micro-patterns were applied to the top and/or bottom surface of the LGF for achieving better luminance property, and it was found that an optimized micro-pyramid pattern exhibited the highest average luminance together with satisfactory luminance uniformity.

• 한국초등과학교육학회지:초등과학교육
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• 제40권3호
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• pp.326-342
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• 2021

본 연구에서는 컴퓨팅 사고의 핵심인 알고리즘 표현을 실험 활동에 적용할 수 있도록 교사를 위한 실험 안내 자료를 개발하였다. 텍스트로 제시된 실험 매뉴얼을 순서도 기호를 사용하여 정보 시각화 프로세스에 따라 직선형, 분기형, 반복형 구조의 알고리즘 형태로 변환하였다. 그 예시로, 자석의 성질을 알아보는 실험을 알고리즘 표현을 적용하여 실험 안내 자료를 개발하였다. 개발된 실험 안내 자료는 정보의 적합성과 판단 여부가 표현된 분기 및 반복의 알고리즘 구조를 가지고 있다는 점과 실험 과정을 시각화하여 표현했다는 측면에서 기존의 순차적으로 표현된 실험 안내 자료와 차이가 있다. 본 연구에서 개발된 실험 안내 자료는 교사들의 알고리즘 사고에 대한 이해와 이를 적용한 실험 실행에 도움을 줄 수 있을 것이라 기대된다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.635-636
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• 2012

In the present work, investigations by high frequency resonance technique for diagnosis of defect frequencies of linear motion unit are reported. Raw vibration signature of the moving parts at different speeds of operation has been demodulated. Envelope detected spectrum is analyzed to evaluate various defect frequencies and their energy levels. Experimentally evaluated frequencies are compared with theoretically determined defect frequencies. These frequency values and their energy levels are used to monitor intrinsic condition of linear motion unit as well as to establish severity of existing/developed defects on the LM guide and inside the LM block. Relative comparisons of linear motion units of the same type are made at various operating speeds under identical conditions of operation on the basis of identified defect frequencies and severity of defects.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1828-1831
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• 2003

There are various sources causing a position error in a linear motor. This paper focuses on error sources from rotational motions of a table and friction. Rotational errors occur due to imperfections during manufacturing and/or assembly of guide ways, and cause a position error at locations of interest. Friction is another factor deteriorating the position error due to its highly nonlinear behavior. The position error of the linear motor was about 20∼30$\mu\textrm{m}$. After compensating the position errors due to rotational error motions and friction. the remaining errors become about 6～8$\mu\textrm{m}$ and 2～3$\mu\textrm{m}$, respectively. It is shown that the positional accuracy of a linear can be greatly improved by compensating the two error sources.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.326-333
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• 2004

This paper presents the structural characteristics analysis of a high-speed horizontal machining center with spindle speed of 50, 000rpm and feedrate of 120m/min. The spindle system is designed based on the built-in motor, angular contact ceramic ball bearings, oil-air lubrication and oil-jacket cooling method. The X-axis and Y-axis feeding systems are composed of the linear motor and linear motion guides, and the Z-axis feeding system is composed of the servo-motor, ball screw and linear motion guide. The structural analysis model of the high-speed horizontal machining center is constructed by the finite element method, and the validity of structural design is estimated based on the structural deformation of the high-speed horizontal machining center and spindle nose caused by the gravity and inertia forces.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1975-1980
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• 2004

The three-dimensional flow in a turbine nozzle guide vane passage causes large secondary loss through the passage and increased heat transfer on the blade surface. In order to reduce or control these secondary flows, a linear cascade with a contoured endwall configuration was used and changes in the three-dimensional flow field were analyzed and discussed. Measurements of secondary flow velocity and total pressure loss within the passage have been performed by means of five-hole probes. The investigation was carried out at fixed exit Reynolds number of $4.0{\times}10^5$. The objective of this study is to document the development of the three-dimensional flow in a turbine nozzle guide vane cascade with modified endwall. The results show that the development of passage vortex and cross flow in the cascade composed of one flat and one contoured endwalls are affected by the flow acceleration which occurs in contoured endwall side. The overall loss is reduced near the flat endwall rather than contoured endwall.

• 한국생산제조학회지
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• 제19권4호
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• pp.553-561
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• 2010

In flat panel display or semiconductor industries, they install the equipments with fine line width and high throughput for fabrication and inspection. The equipments are required to have the linear stage which can position the work-piece with high speed, fine resolution on wide range of motion. In this paper, a precision planar linear XY stage is proposed. The stage has a symmetric planar window configuration and is guided by air-bearings on granite plate. The symmetric planar window configuration makes the stage has robustness against dynamic and thermal disturbances. The air-bearings let the stage move smooth on straight guide bar and flat granite surface. The stage is actuated by linear motor with Halbach magnet array (HMA). HMA generates more confined magnetic flux than conventional array. The linear motors are optimized by using sequential quadratic programming (SQP) with the several constraints that are thermal dissipation, required power, force ripple and so on. The planar linear XY stage with the symmetric planar configuration and the linear motors is implemented and then the performance such as force ripple, resolution and stroke are evaluated.

• 대한조선학회논문집
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• 제43권3호
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• pp.340-350
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• 2006

This paper is concerned with a practical guide for the ultimate longitudinal strength assessments of ships' hull structure. Rigorous non-linear structural analysis for three tanker models has been carried out to examine the ultimate strength behavior. Formula of estimating the ultimate longitudinal strength has been proposed which is modified with the results of non-linear finite element analysis of hull girders. Computational reliability and accuracy of the large-scale non-linear finite element analysis and the proposed simplified formula are verified through comparing their results with that of 1/3 scale frigate model test and DNVs program. Additionally, the ultimate longitudinal strength for ten tanker models is compared with those by the method specified in the 2nd Draft of common structural rule for tankers, which is being developed by IACS.