• 한국소음진동공학회논문집
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• 제15권5호
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• pp.595-603
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• 2005

In this work, the multiple dynamic absorber( MDA ) is introduced to reduce several vibration modes of shadow mask simultaneously and its design method is developed from the theory of the simple dynamic absorber. When designing the dynamic absorber, there are three significant design parameters such as mass, damping ratio and tuning frequency. Therefore the sensitivity analysis for those parameters has been executed in order to find out the design criteria of multiple dynamic absorber using the finite element model of shadow mask. The multiple dynamic absorber(MDA) designed by the proposed method is tested theoretically and experimentally to estimate the efficiency of vibration reduction. From the results, it is verified that the method is feasible to apply the system having the multiple nitration modes and more efficient than the thin wire-type damper used commercially to reduce the vibration of shadow mask.

• 한국정보통신학회논문지
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• 제10권2호
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• pp.308-314
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• 2006

수 마이크로 단위로 계측되는 반도체 COG의 검사 정밀도를 높이기 위해서 라인스캔 카메라가 이용된다. 여러 가지 불량 요인 중 이물질 검출은 COG 패턴이 미세하고 복잡하기 때문에 불량 자동 검사 단계에서 가장 어려운 기술이었다. 본 논문에서는 매칭 속도를 높이기 위하여 2단계 영역분할 템플릿 매칭 방법을 제안하였다. 아울러 수 마이크로 단위의 이물짙 검출을 위하여 그라디언트 마스크와 AND 연산을 이용한 새로운 방법을 제안하였다. 제안된 2단계 템플릿 매칭을 사용한 방법은 기존의 상관 계수 이용법 에 비해 0.3-0.4초 매칭 속도를 향상시켰다. 그리고 제안된 마스크 적용 이물질 검출방법은 기존 마스크를 이용하지 않은 방법에 비해 불량 검출률을 $5-8\%$ 향상시켰다.

• 반도체디스플레이기술학회지
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• 제18권2호
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• pp.48-52
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• 2019

Virtual metrology, which is one of APC techniques, is a method to predict characteristics of manufactured films using machine learning with saving time and resources. As the photoresist is no longer a mask material for use in high aspect ratios as the CD is reduced, hard mask is introduced to solve such problems. Among many types of hard mask materials, amorphous carbon layer(ACL) is widely investigated due to its advantages of high etch selectivity than conventional photoresist, high optical transmittance, easy deposition process, and removability by oxygen plasma. In this study, VM using different machine learning algorithms is applied to predict the thickness of ACL and trained models are evaluated which model shows best prediction performance. ACL specimens are deposited by plasma enhanced chemical vapor deposition(PECVD) with four different process parameters(Pressure, RF power, $C_3H_6$ gas flow, $N_2$ gas flow). Gradient boosting regression(GBR) algorithm, random forest regression(RFR) algorithm, and neural network(NN) are selected for modeling. The model using gradient boosting algorithm shows most proper performance with higher R-squared value. A model for predicting the thickness of the ACL film within the abovementioned conditions has been successfully constructed.

• 대한전자공학회논문지
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• 제24권1호
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• pp.97-101
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• 1987

The edge, a discontinuity or abrupt change in the gray-level or color, is a fundamentally important primitive feature of an image necessary for the image analysis and classification. Two-dimensional 3x3 compass gradient operators (ex. Sobel, Prewitt, and Kirsch operators)are commonly used in the edge detection and usually detect 8 compass directional components. In this paper, we present a new interpretation of the relationships between the resulting 8 gradient magnitudes and the 8 intensity values of neighboring pixels which are covered by the two-dimensional 3x3 mask. It is expected that a new gradient edge operator may be designed by changing the eigenvalues in the transform domain and the fast optical edge operator may be implemented by using the optical system.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.127-132
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• 2000

Though the increment of using computer vision system, there are lots of difficulties to measure precisely because of measurement error or distortion phenomenon. Among these reasons, the distortion of edge is dominant reason which is occurred by the blurred image. So, the problem of clear judgment about image focal point is very important. We must fix the discrimination criteria which is collected by image recognition of precise focus. To solve these problems, we compare with make processing methods using image intensity gradient, laplacian, and sum -modified laplacian operator. These experimental results showed modified mask processing method is effective.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2005년도 추계학술대회지
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• pp.203-208
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• 2005

수 마이크로 단위로 계측되는 반도체 COG의 정밀도를 높이기 위해서 라인스캔 카메라로 영상을 획득한다. 하지만 불량 검출은 스캔속도와 조명조건에 매우 민감하다. 본 논문에서는 불량이 없는 COG 영상과 입력영상을 정합하여 불량 검출의 정확성을 높이기 위한 방법에 대하여 제안하였다. 두 이미지를 정합시키는 방법으로 영역분할 템플릿 매칭 방법을 사용하였으며 그라디언트 마스크와 AND 연산하여 최종 결과 영상을 획득하였다. 제안된 방법은 다른 이미지 정합 법에 대하여 커다란 성능향상을 보임을 일련의 실험들을 통하여 보여준다.

• 한국초전도ㆍ저온공학회논문지
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• 제25권4호
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• pp.24-27
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• 2023

Until now, many research activities have been conducted to commercialize high-temperature superconducting (HTS) wires for electric applications. Most of all researchers have focused on enhancing the piece length, critical current density, mechanical strength, and throughput of HTS wires. Recently, HTS magnet for generating high magnetic field shows degraded performance due to the deformation of HTS wire by high electro-magnetic force. The deformation can be derived from widthwise thickness non-uniformity of HTS wire mainly caused by wet processes such as electro-polishing of metal substrate and electro-plating of copper. Gradient sputtering process is designed to improve the thickness uniformity of HTS wire along the width direction. Copper stabilizing layer is deposited on HTS wire covered with specially designed mask. In order to evaluate the thickness uniformity of HTS wire after gradient sputtering process, the thickness distribution across the width is measured by using the optical microscope. The results show that the gradient deposition process is an effective method for improving the thickness uniformity of HTS wire.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 D
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• pp.2384-2386
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• 2003

This paper presents an image processing method to recognize object's position from images for robot control applications. The Sobel Mask and the Dialated Gradient Mask algorithms are used to extract and refine the edge of the object. The inside of the extracted edge is filled with '1's for calculation of the center of mass to identify object's position. We propose a heuristic method which averages the positions of the objects in 10 frames to reject noises, and discuss the application of the proposed method to robot control.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2003년도 추계학술대회 및 정기총회
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• pp.201-206
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• 2003

In clinical practice, CT Angiography is a powerful technique for the visualziation of blood flow in arterial vessels throughout the body. However CT Angiography images of blood vessels anywhere in the body may be fuzzy if the patient moves during the exam. In this paper, we propose a novel technique for removing global motion artifacts in the 3D space. The proposed methods are based on the two key ideas as follows. First, the method involves the extraction of a set of feature points by using a 3D edge detection technique based on image gradient of the mask volume where enhanced vessels cannot be expected to appear, Second, the corresponding set of feature points in the contrast volume are determined by correlation-based registration. The proposed method has been successfully applied to pre- and post-contrast CTA brain dataset. Since the registration for motion correction estimates correlation between feature points extracted from skull area in mask and contrast volume, it offers an accelerated technique to accurately visualize blood vessels of the brain.

• 한국정보과학회논문지:소프트웨어및응용
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• 제36권11호
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• pp.901-911
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• 2009

본 논문에서는 연속 프레임에서 움직임이 큰 얼굴을 자동으로 추적하기 위해 두 단계 합성 기울기 지형 생성 방법을 제안한다. 본 제안 방법은 다음과 같은 세 가지 단계로 이루어진다. 첫째, 활성 외곽선이 빠르게 수렴하기 위한 두 단계 해상도 기울기 맵을 생성한다. 둘째, 연속하는 프레임 간의 변위를 파악하고 주변 배경을 제거하기 위하여 이전 프레임과 현재 프레임의 합성 기울기 맵과 차별 마스크를 산정하여 가중 합성 기울기 맵을 구성한다. 셋째, 활성 외곽선이 지역적 최소값에 수렴하는 것을 막기 위해 닫기 연산을 사용하여 에너지 비탈면을 생성한다. 이 때, 닫기 연산의 계산 비용 문제는 빠른 닫기 연산을 통해 해결한다. 제안방법의 정확성을 평가하기 위해 기존 활성 외곽선 모델 기반 방법들과 제안방법의 수행 결과를 통한 육안 평가와 활성 외곽선의 평균 에너지 변화를 통한 견고성 평가를 수행하고, 수행 시간을 분석한다. 실험 결과 제안방법의 경우 배경의 영향을 받지 않으면서 얼굴의 움직임이 큰 경우에도 빠르고 정확하게 추적할 수 있었다.