• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.331-332
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• 2006

Transport systems which are the important part of the factory automation have much influence on improving productivity. Object transport systems are driven typically by the magnetic field and conveyer belt. In recent years, as the transmission and processing of information is required more quickly, demands of optical elements and semiconductors increase. However, conventional transport systems are not adequate for transportation of those. The reason is that conveyor belts can damage precision optical elements by the contact force and magnetic systems can destroy the inner structure of semiconductor by the magnetic field. In this paper, the levitation transport system using ultrasonic wave is developed for transporting precision elements without damages. Vibration modes of each flexural beam are verified by using Laser Scanning Vibrometer.

• 한국생산제조학회지
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• 제23권6호
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• pp.547-554
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• 2014

CVD SiC is a perfect material used for molds/dies in hot press molding of glass lens. In its fabrication process, nano-precision polishing is essential finally. For this purpose, a novel polishing method using MCF (Magnetic Compound Fluid) slurry is proposed. In this method, MCF slurry is supplied into a given gap between the workpiece and a MCF slurry carrier, and constrained within the polishing zone by magnetic forces from permanent magnet. In this paper, after an experimental rig used to actually realize the proposed method has been constructed, the fundamental polishing characteristics of CVD SiC such as the effects of process parameters including MCF slurry composition on work-surface roughness were experimentally investigated. As a result, nano-precision surface finish of CVD SiC was successfully attained with MCF slurry and the optimum process parameters for obtaining the smoothest work-surface were determined.

• Macromolecular Research
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• 제17권3호
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• pp.181-186
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• 2009

We fabricated ordered micro/nano patterns induced by controlled dewetting on the topographically patterned PS/P4VP bilayer thin film. The method is based on utilizing microimprinting lithography to induce a topographically heterogeneous bilayer film that allows the controlled dewetting upon subsequent thermal annealing. The dewetting that was initiated strictly at the boundary of the thicker and thinner regions was guided by the presence of the topographic structure. The dewetting front velocity of the microdomains in the confined regions was linearly proportional to the measurement time, which enabled us to control the size of the dewet domain with annealing time. In particular, the submicron sized dot arrays between lines were generated with ease when the dewetting was confined into geometry with a few microns in size. The kinetically driven, non-lithographical pattern structures accompanied the pattern reduction to 400%. The pattern arrays on a transparent glass substrate were especially useful for non-circular microlens arrays where the focal length of the lens was easily tunable by controlling the thermal annealing.

• International Journal of Korean Welding Society
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• 제1권2호
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• pp.23-29
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• 2001

In this study, a preview-sensing visual sensor system is constructed far weld seam tracking in GMA welding. The visual sensor system consists of a CCD camera, a diode laser system with a cylindrical lens, and a band-pass-filter to overcome the degrading of image due to spatters and/or arc light. Among the image processing methods, Hough transform method is compared with the central difference method from a viewpoint of the capability for extracting the accurate feature position. As a result, it was revealed that Hough transform method can more accurately extract the feature positions and it can be applied to real time weld seam tracking. Image processing which includes Hough transform method is carried out to extract straight lines that express laser stripe. After extracting the lines, weld joint position and edge points are determined by intersecting the lines. Even though the image includes a spatter trace on it, it is possible to recognize the position of weld joint. Weld seam tracking was precisely implemented with adopting Hough transform method, and it is possible to track the weld seam in the case of offset angle is in the region of $\pm$ $15^{\circ}$.

• 비파괴검사학회지
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• 제35권2호
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• pp.141-149
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• 2015

전자제품에 필수적으로 사용되는 전자회로의 제작 시, 반도체 위에 증착하는 박막의 산화를 방지하기 위하여 molybdenum을 증착한다. Molybdenum 박막 증착 시 표면의 particle 또는 dust의 존재는 밀착력 감소 및 성능 저하, 수명 단축, 안전도 저하를 유발한다. 본 논문에서는 particle의 유무에 따른 molybdenum 박막 증착부의 변화를 보기 위하여, 두 가지 glass substrate를 대상으로 손상 측정 실험을 하였다. Sputtering 증착 기법으로 molybdenum이 glass substrate에 직접 코팅이 되는 clean과 dirty 두 종류의 molybdenum 박막을 제작하고, 손상 측정을 위해 반사형 디지털 홀로그래피를 구성하였다. 반사형 디지털 홀로그래피는 간섭계의 구성이 손쉽고 다양한 배율렌즈를 적용하여 측정영역에 다양성을 줄 수 있으며, 측정시간이 타 기법에 비해 짧다는 장점을 가진다. 실험 결과로부터 반사형 디지털 홀로그래피가 박막의 손상 및 결함 측정에 유용한 기술임을 확인하였다.

• 한국안광학회지
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• 제16권2호
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• pp.107-115
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• 2011

목적: 안경렌즈 조제가공을 위한 보급형 전자동 옥습기 개발을 위해 설계하고 제작하고자 한다. 방법: 보급형 전자동 옥습기의 주요 설계도를 캐드로 그려서 제작에 필요한 정보를 얻었다. 이 데이터를 기본으로 보급형 자동옥습기 개발을 위해 시제품을 제작 하였다. 결과: 무패턴 모드는 외부 자동 취형기에서 안경테의 렌즈삽입부 정보를 RS232C 전송방식으로 형판 없이도 작동할 수 있었고, 패턴 모드는 형판을 이용해서 개발품의 좌측에 장착하여 작동할 수 있었다. 보급형 자동옥습기는 헤드부, 오토암부, 형판고정부 그리고 연삭부와 같은 주요 요소들로 구성되었다. 헤드부는 좌우모터와 상하모터의 작동을 이용하여 안경렌즈의 연삭을 제어하였다. 연삭부는 유리 재질, 플라스틱 재질, V-홈 그리고 광택을 낼 수 있는 연삭휠로 구성하였다. 슬라이드는 고정된 형판의 하부에 구비되었고, 고정 샤프트에 의해 회전되는 형판이 슬라이드부에 의해 지지할 수 있었다. 형판고정부는 안경사의 수동적인 조작에 의해 헤드파트를 승강 및 좌우 이동시킬 수 있게 하였다. 연삭휠의 분당 회전수를 3,600 rpm으로 최적화 하였다. 결론: 패턴리스와 패턴 렌즈 가공이 가능한 보급형 자동옥습기를 설계 및 제작하여 시제품 제작에 성공하였다. 최소의 비용으로 효율적이고 간편하게 조제가공이 가능하여 안경사들에게 큰 도움이 될 수 있을 것으로 예상된다.

• Korea-Australia Rheology Journal
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• 제19권4호
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• pp.191-199
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• 2007

Precision injection molding process is of great importance since precision optical products such as CD, DVD and various lens are manufactured by those process. In such products, birefringence affects the optical performance while residual stress that determines the geometric precision level. Therefore, it is needed to study residual stress and birefringence that affect deformation and optical quality, respectively in precision optical product. In the present study, we tried to predict residual stress, final shrinkage and birefringence in injection molded parts in a systematic way, and compared numerical results with the corresponding experimental data. Residual stress and birefringence can be divided into two parts, namely flow induced and thermally induced portions. Flow induced birefringence is dominant during the flow, whereas thermally induced stress is much higher than flow induced one when amorphous polymer undergoes rapid cooling across the glass transition region. A numerical system that is able to predict birefringence, residual stress and final shrinkage in injection molding process has been developed using hybrid finite element-difference method for a general three dimensional thin part geometry. The present modeling attempts to integrate the analysis of the entire process consistently by assuming polymeric materials as nonlinear viscoelastic fluids above a no-flow temperature and as linear viscoelastic solids below the no-flow temperature, while calculating residual stress, shrinkage and birefringence accordingly. Thus, for flow induced ones, the Leonov model and stress-optical law are adopted, while the linear viscoelastic model, photoviscoelastic model and free volume theory taking into account the density relaxation phenomena are employed to predict thermally induced ones. Special cares are taken of the modeling of the lateral boundary condition which can consider product geometry, histories of pressure and residual stress. Deformations at and after ejection have been considered using thin shell viscoelastic finite element method. There were good correspondences between numerical results and experimental data if final shrinkage, residual stress and birefringence were compared.

• 한국학교보건학회지
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• 제12권1호
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• pp.71-84
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• 1999

This study attempts to identify the self-image of eyeglass wearers with Q-methodology. Preliminary Q-statements were collected through personal and telephone interviews and based in consultation with reference books, eyeglass wearers, an optician and an oculist. Finally, 34 Q-samples were seleted. The results were analyzed by a Q-factor with a PC QUANL Program. The self-image of eyeglass wearers were found to revolve around three types: Type 1. They feel that eyeglasses have a negative influence on image and that they uncomfortable. In addition, other people have a negative bias toward people who wear eyeglasses. As a result of these negative prejudices and inconveniences, there is a tendency to wear contact lens or have laser operations. Type 2. They feel less uncomfortable comparatively, when explained that glasses can help improve their image. When explained as a fashion accessory, negative prejudices almost disappeared. Type 3. They show a positive reaction when explained that spectacles are also used for sight protection. Howerer, they are sensitive to changes in their complexion as a result of eyeglass wear and place much importance in the design of glass frames. The significance of this study is to suggest basic data for a mediation device that improve the image of eyeglass wearers discovery and analysis of these three types.

• 한국안광학회지
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• 제8권2호
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• pp.25-29
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• 2003

자외선과 전자파를 동시에 차단하는 선글라스렌즈를 제작하기 위하여 유리가판 위에 자성재료인 페라이트에 Ni를 여러 가지 조성비로 첨가한 니켈페라이트 박막 $Ni_xFe_{3-x}O_4$을 페라이트 도금법으로 제작하였다. 이들은 모두 스피넬 구조의 단일상임을 확인할 수 있었으며 육안으로 관찰할 때 거울면과 같은 광택을 가졌으며, 손톱으로 긁었을 때 흠집이 생기지 않는 강도를 보였다. 니켈페라이트는 400nm 부근에서부터 급격히 투과율이 떨어져 자외선을 차단하는데 효과적인 양상을 보이고 있으며 그 중에서 x = 0.09의 Ni 조성비가 자외선 차단효과가 가장 좋은 깃으로 나타났다. 이는 타사제품과 비교하여 자외선 차단효과는 크게 떨어지지 않으므로, 전자파 차단효과가 있는 $Ni_xFe_{3-x}O_4$ 페라이트를 코팅한 선글라스를 착용함으로서 유해전자파와 자외선을 동시에 차단하는 효과를 얻을 수 있을 것이다.

• 전자공학회논문지SC
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• 제43권1호
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• pp.1-6
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• 2006

경면물체의 형상과 두께를 측정하는데 있어 접촉식 센서가 가지고 있는 문제점을 해결하기 위해 홀로그램 레이저 다이오드와 자동 전력 제어를 이용하여 성능이 좋은 비접촉식 광센서를 개발하였다. 접촉식 센서에서는 센서 프로브가 측정 대상체와 계속해 접촉하므로 프로브의 마모로 인한 측정왜곡이 발생하게 된다. 이를 극복하기 위해 플라스틱렌즈와 CD 플레이어의 광학 픽업장치를 홀로그램 레이저로 구성하는 저가의 비접촉 센서를 제안한다. 비접촉식 광센서는 대상물체 쪽으로 움직이면서 포커스 에러 신호를 얻어 투명판의 형상과 두께를 측정할 수 있다. 센서 내부 온도를 ${\pm}0.1^{\circ}$ 제어한 상태에서 다수의 실험 측정을 수행하여 ${\pm}2{mu}m$의 측정 오차를 가지는 우수한 결과를 보이고 있다.