• Proceedings of the Korean Information Science Society Conference
• /
• 1998.10b
• /
• pp.407-409
• /
• 1998

루프 몸체를 복제하는 루프 펼침을 외부 루프에 대하여 적용하면, 루프 내포체의 데이터 지역성이 개선된다. 펼침 횟수 증가에 따른 루프 내포체의 데이터 지역성 변화를 예측하였고, 예측 결과를 행렬 곱셈 프로그램에 대하여 실행 시간과 개시 미스 변화를 측정하여 검증하였다. 펼침 횟수는 증가함에 따라, 초반에는 실행 시간과 캐시 미스가 급격히 감소하다 점점 감소폭이 줄어드는 기하급수적 변화를 보였다. 이 결과는 데이터 지역성 개선을 위한 외부 루프 펼침 변환을 적용 할 때, 작은 값(최대 405회)의 펼침으로 프로그램 성능 향상을 기대할 수 있음을 의미한다. 한편, 컴파일러에 의한 루프 펼침을 적용할 때, 불필요하게 많은 펼침 횟수의 펼침 효과에 대하여 분석 할 필요가 없음을 나타낸다

• Composites Research
• /
• v.26 no.3
• /
• pp.155-159
• /
• 2013

This paper reviewed the continuous fiber tow spreading technologies and its applications. The effect of the continuous fiber tow spreading in manufacturing process of continuous fiber reinforced thermoplastic composite was introduced theoretically. The fiber tow spreading technologies were categorized according to the spreading medium and its order during manufacturing process. The general principles, the applications, and the merits and demerits of fiber tow spreading technologies were introduced. Furthermore, the proposal for future direction of research on this issue was considered in this study.

• Composites Research
• /
• v.28 no.5
• /
• pp.249-253
• /
• 2015

This paper reports a study on a method for achieving lightweight thermoplastic laminate composites referred to as tow spreading technology. Thickness of an unspread 12 K carbon fiber tow is reduced by increasing the tow width from 7 mm to 20 mm. The polypropylene (PP) film was used to stabilize and impregnate the spread tow, covering it into a partially consolidated prepreg: 12 K carbon fiber spread tow/PP. Laminates were fabricated from the spread tow prepreg and control laminate composites were produced from unspread tow prepreg consisting of 12 K carbon fiber and PP. The void content, tensile and flexural properties of the composite laminates were investigated. Consequently, the spread tow laminate composite exhibited lower void content and improved mechanical properties.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2019.11a
• /
• pp.217-218
• /
• 2019

홀로그램을 재생하기 위한 SLM(Spaital Light Modulator)에서 홀로그램의 실수 정보 혹은 위상 정보를 사용한다. 본 논문에서는 홀로그램의 위상 정보를 효율적으로 압축하기 위한 방식을 제안한다. 홀로그램 압축 표준 코덱 개발에서는 표준 코덱을 기점으로 전후처리를 이용하여 압축효율의 개선 시키는 연구를 진행 중이다. 위상 정보는 -𝜋에서 +𝜋의 제한된 동적 범위를 가진다. 이는 위상 정보 사이의 공간적인 상관도를 낮추며 압축효율을 크게 떨어뜨리는 요인이 된다. 위상 펼침 기법을 이용하여 위상 정보 간의 공간적인 상관도를 확보한다. 공간적인 상관도가 확보된 위상 정보에 JPEG2000 표준 코덱의 입력을 고려하여 양자화한 뒤 압축 후 복원하고 효율을 분석한다.

• Journal of the Korean Society of Radiology
• /
• v.3 no.2
• /
• pp.23-26
• /
• 2009

This study proposed an improved center array-sequencing phase unwrapping (ICASPU) algorithm. 2% agarose phantom dopped with 0.6mM/l MnCl2 was used with clinical 1.5T MRI system and commercial knee coil. Obtained k-space data(raw-data) was transmitted to PC and reconstructed into phase image with MATLAB software. Previous center array-sequence phase unwrapping algorithm wascompared with proposed ICASP algorithm using second order regression analysis. As a result, we found that the amount of error on proposed ICASPU method is less about 5 times than that of previous CASPU method. In this study, we exploit improved Center array-sequence phase unwrapping algorithm and expect to apply to images including phase informations.

• Korean Journal of Optics and Photonics
• /
• v.18 no.2
• /
• pp.122-129
• /
• 2007

Generally, many kinds of phase unwrapping algorithm are used to obtain three-dimensional features in digital holography. The Goldstein algorithm is ra epresentative method. which requires small memory capacity and short execution time fer an unwrapping process. However, the Goldstein algorithm has some problems when the dipole residue is located at the boundary. When the opposite residues are located at the boundary and the distance between the opposite residues is longer than the boundary, an incorrect branch cut occurs and results in incorrect calculation. We have modified the Goldstein algorithm to solve the incorrect calculation problem using boundary information. We found that the modified Goldstein algorithm could resolve the Goldstein algorithm's problem.

• Proceedings of the Optical Society of Korea Conference
• /
• 2007.02a
• /
• pp.131-132
• /
• 2007

• Korean Journal of Optics and Photonics
• /
• v.26 no.3
• /
• pp.147-154
• /
• 2015

We propose a method for simultaneously measuring the front and back surface profiles of transparent optical components. The proposed method combines dual-wavelength transmission deflectometry with liquids to record distorted phases at different wavelengths, and then numerically reconstructs the three-dimensional phase information to image the front and back surfaces of the lens. We propose a theoretical model to determine the surface information, and a bifocal lens is experimentally investigated. Unlike conventional transmission deflectometry, our proposed method supports direct observation of the front and back surface profiles of the optical elements.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2004.10a
• /
• pp.146-154
• /
• 2004

In this study, numerical analysis has been performed to investigate the flow characteristics of a drag improvement device which is designed to achieve accurate impact point. The drag increase due to drag improvement device has been analyzed. And the effect of spread angle and location of drag improvement device has also been investigated. The drag improvement device with 20 degree spread angle increased the drag 3.5 times. The corresponding weight of the device is found out to be 26g.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2020.07a
• /
• pp.321-322
• /
• 2020

본 논문에서는 Intra 코딩 기반의 위상 홀로그램 압축 방법을 제안한다. 제안하는 방법은 다음과 같다. 홀로그램을 Intra 코딩의 블록 단위로 세그먼트를 나누는 과정, Intra 코딩의 예측을 고려한 위상 펼침 과정, H.265/HEVC 입력을 고려한 양자화 과정, 마지막으로 H.265/HEVC를 이용한 압축과정으로 구성된다. 제안한 알고리즘은 위상정보에 아무런 전후처리를 하지않고 H.265/HEVC를 압축한 결과보다 100:1 이상의 고압축률 구간에서 압축효율이 향상되었다.