• 방송공학회논문지
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• 제13권1호
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• pp.109-118
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• 2008

텍스처 영상 압축은 JPEG과 같은 영상 압축 표준을 사용한다. 일반 텍스처 영상에는 JPEG으로도 좋은 압축 성능을 내지만 패치 텍스처 영상은 이러한 영상 압축 기술로 압축했을 때 좋은 압축 성능을 보이지 못하였다. 이를 보완하고 압축 성능을 높이기 위해 기존의 패치 텍스처 영상에 주변 화소간에 색차를 줄이기 위한 전처리 기술을 소개하고, 제안된 기술과 JPEG 압축을 순서대로 적용하였을 때 압축 성능이 23%에서 45%까지 향상됨을 보이고자 한다.

• 방송공학회논문지
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• 제2권2호
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• pp.136-145
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• 1997

일반적으로 3차원 메시 모델은 많은 정점(vertex)과 다각형으로 이루어져 있을 뿐만 아니라 정점 위치 각각은 3차원 좌표에서 세 개의 32비트 부동소수점수로 표현되기 때문에, 모델을 표현하기 위해 필요한 데이터 량은 매우 많다. 따라서 3차원 모델을 효과적으로 저장 및 전송하기 위한 압축 기법은 필수적으로 요구된다. 이를 위해 본 논문에서는 예측 잉여신호 벡터 양자화를 이용한 3차원 모델 압축 기법을 제안한다. 기본적인 개념은 3D 모델을 이루는 서로 인접한 정점 위치들간에 존재하는 높은 상관도와 정점 위치 자체가 지니는 벡터 특성에 근거한다. 실험 결과에 따르면 제안한 방법이 기존의 압축 방법에 비해 높은 압축율을 얻을 수 있으며 정점 위치 정보를 점진적으로 전송할 수 있는 장점을 지닌다.

• 한국CDE학회논문집
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• 제13권1호
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• pp.1-7
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• 2008

Data compression becomes increasingly an important issue for reducing data storage spaces as well as transmis-sion time in network environments. In 3D geometric models, the normal vectors of faces or meshes take a major portion of the data so that the compression of the vectors, which involves the trade off between the distortion of the images and compression ratios, plays a key role in reducing the size of the models. So, raising the compression ratio when the normal vector is compressed and minimizing the visual distortion of shape model's shading after compression are important. According to the recent papers, normal vector compression is useful to heighten com-pression ratio and to improve memory efficiency. But, the study about distortion of shading when the normal vector is compressed is rare relatively. In this paper, new normal vector compression method which is clustering normal vectors and assigning Representative Normal Vector (RNV) to each cluster and using the angular deviation from actual normal vector is proposed. And, using this new method, Visually Undistinguishable Lossy Compression (VULC) algorithm which distortion of shape model's shading by angular deviation of normal vector cannot be identified visually has been developed. And, being applied to the complicated shape models, this algorithm gave a good effectiveness.

• 한국CDE학회논문집
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• 제7권2호
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• pp.81-88
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• 2002

Transmission of 3D shape model through Internet has become one of the hottest issues in these days. Presented in this paper is a new approach for the rapid transmission of the geometry data of the shape model. By analyzing the important three factors, the shape fidelity, the file size, and the decompression time, for the compression, we point out the potential problems of previous approaches of using the deltas between consecutive vertices and propose an alternative of directly using the position values of vertices of the model. It turns out that the proposed approach has smaller file size, has lesser distortion in the model, and the decompression is faster.

• 한국산업경영시스템학회:학술대회논문집
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• 한국산업경영시스템학회 2002년도 춘계학술대회
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• pp.455-460
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• 2002

As the transmission of 3D shape models through Internet becomes more important, the compression issue of shape models gets more critical. The issues for normal vectors have not yet been explored as much as it deserves, even though the size of the data for normal vectors can be significantly larger than its counterparts of topology and geometry. Presented in this paper is an approach to compress the normal vectors of a shape model represented in a mesh using the concept of clustering. It turns out that the proposed approach has a significant compression ratio without a serious sacrifice of the visual quality of the model.

• 산업경영시스템학회지
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• 제27권4호
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• pp.77-82
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• 2004

Being in an internet era, the rapid transmission of 3D mesh models is getting more important and efforts toward the compression of various aspects of mesh models have been provided. Even though a mesh model usually consists of coordinates of vertices and properties such as colors and normals, topology plays the most important part in the compression of other information in the models. Despite the extensive studies on Edgebreaker, the most frequently used and rigorously evaluated topology compressor, the probability distribution of its five op-codes, C, R, E, S, and L, has never been rigorously analyzed yet. In this paper, we present probability distribution of the op-codes which is useful for both the optimization of the compression performance and a priori estimation of compressed file size.

• 한국농공학회논문집
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• 제57권6호
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• pp.141-152
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• 2015

Most of agricultural structures are consisted of complex components and exposed to various boundary conditions. There have been no ways to express those structures exactly for model experiment. As an alternative, 3D printer can produce any type of solid model. However, there are limited informations related to structural experiments using 3D printer. The object of this study gives the basic informations to structural engineers who try to use 3D printer for model experiment. When PLA was used as a supplier for 3D printer, the outcomes showed less heat deformation to compare with ABS. To test the material properties, two kinds of experiments (three-point flexibility test and compression test) were executed using universal testing machine. In three-point flexibility test, plastic hinge and its deformation were developed as observed in material such as steel. The behavior was in a linear elastic state, and elastic bending modulus and yield force were evaluated. In the compression test using unbraced columns with hinge-hinge boundary condition, the constant yield forces were observed regardless of different lengths in all columns with same section size, whereas the compressive elastic modulus was increased as the length of column was increased. The suggested results can be used for model experiments of various agricultural structures consisted of single material.

• Fibers and Polymers
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• 제7권4호
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• pp.389-397
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• 2006

The beneficial effects of graduated compression stockings (GCS) in prophylaxis and treatment of venous disorders of human lower extremity have been recognized. However, their pressure functional performances are variable and unstable in practical applications, and the exact mechanisms of action remain controversial. Direct surface pressure measurements and indirect material properties testing are not enough for fully understanding the interaction between stocking and leg. A three dimensional (3D) biomechanical mathematical model for numerically simulating the interaction between leg and GCS in dynamic wear was developed based on the actual geometry of the female leg obtained from 3D reconstruction of MR images and the real size and mechanical properties of the compression stocking prototype. The biomechanical solid leg model consists of bones and soft tissues, and an orthotropic shell model is built for the stocking hose. The dynamic putting-on process is simulated by defining the contact of finite relative sliding between the two objects. The surface pressure magnitude and distribution along the different height levels of the leg and stress profiles of stockings were simulated. As well, their dynamic alterations with time processing were quantitatively analyzed. Through validation, the simulated results showed a reasonable agreement with the experimental measurements, and the simulated pressure gradient distribution from the ankle to the thigh (100:67:30) accorded with the advised criterion by the European committee for standardization. The developed model can be used to predict and visualize the dynamic pressure and stress performances exerted by compression stocking in wear, and to optimize the material mechanical properties in stocking design, thus, helping us understand mechanisms of compression action and improving medical functions of GCS.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2008년도 학술대회 1부
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• pp.461-468
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• 2008

가상현실 및 증강 현실 응용 특히 디지털 패션과 같은 응용분야에서 아바타에 여러 가지 형태의 의복을 입히고 장신구들을 장식하여 보다 현실감이 나는 3차원 애니메이션을 제작한 다음 인터넷을 통하여 개인용 컴퓨터는 물론 핸드폰 같은 휴대용 정보단말기에 표현하려는 요구가 증가하고 있다. 하지만 3차원 모델을 실감나게 표현하는데 필요한 데이터의 용량이 매우 크고 네트워크의 속도 문제와 단말기에 장착된 메모리 장치의 제한적인 성능 문제등으로 인하여, 3차원 영상의 효과적인 전송 및 실감나는 표현은 매우 어렵다. 본 논문에서는 3차원 애니메이션에서 사용되는 데이터를 압축하는데, 3차원 모델 데이터를 군집화하여 애니메이션에 필요한 저장 공간을 줄여서 휴대용 정보단말기에서도 3차원 모델을 자연스럽게 렌더링할 수 있게 하는 기법을 제안하고자 한다. 제안된 기법은 각종 디포머블 오브젝트에도 응용될 수 있으며, 기존의 정적인 형상 압축 기술과 연계하여 좀 더 높은 압축을 가능하게 할 것으로 기대된다.

• 한국안전학회지
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• 제19권3호
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• pp.95-100
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• 2004

H-pile can be more easily driven than pipe pile by pile driver and shows high skin friction and plugging effect. And lately It is well grown that the high strength H-pile has been widely used f3r pile foundations. To compare the skin frictions of H piles under different density soil conditions, this paper presents results of a series of model tests on vertically loaded group piles. Model piles made of steel embedded in weathered granite soil were used in this study. Pile arrangements $(2\times2,\;3\tunes3)$, pile space(2D, 4D, 6D), and soil density$(D_r=40\%,\;80\%)$ were tested. The main results obtained from the model tests can be summarized as follows. The series of tests found that compression load for group piles increases as number of piles increase and piles space ratic decrease to $D_r=40\%$ of soil density. The analysis also found that the theoretical value of skin friction for group piles is greater than practical value as piles space ratio increases to $D_r=40\%$ of soil density. Piles showed the greatest difference of the skin friction in case that the pile space ratio(S/D) is 6. The theoretical value by Meyerhof and DM-7 showed 1.83 times and 1.32 times respectively as great as practical value in case of S/D=6 and $2\times2$.