• Korean Journal of Computational Design and Engineering
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• v.7 no.2
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• pp.89-95
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• 2002

VRML data, which is mainly structural element, is frequently used for modeling and visualizing 3D objects. Although there can be variations, it is a usual practice to represent 3D shapes in VRML format. Ever since the advent of Internet, there have been strong needs to transfer shape data through Internet. Because of this need, it is necessary to transform a data file in VRML or similar format into a more convenient form to transfer through the network. In a VRML file, a model is sometimes divided into a set of triangle meshes due to several practical reasons. However, this causes various demerits for the fast transmission. Therefore, it is more efficient to merge the mesh sets into one mesh set for the transmission. In this paper, we present the problems in the merge process and the techniques to handle the situation.

• Journal of the Korea Institute of Building Construction
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• v.2 no.4
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• pp.99-104
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• 2002

Recently, the continuous fiber materials has become more important materials to repair and to reinforce concrete structural members. Continuous fiber meshes are effective for shear and confining reinforcement and provide excellent durability when combined with high strength mortar The purpose of this study is to verify the relationship between concrete strength and the ductility of inner concrete confined laterally by continuous fiber meshes. For this study, Experimental studies were conducted by compressive members using the cast frame of high strength mortar and continuous fiber meshes. Therefore, the result shows that compressive strength and ductility has improved according to the amount of the fiber meshes, and that the lateral confined effect of members with 3- or 4-axis mesh arrangement is bigger than that of members with 2-axis mesh. These data have to be used to verify the characteristic of concrete structure members reinforced continuous fiber mesh.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05a
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• pp.535-538
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• 2003

본 논문에서는 얼굴 영상으로부터 워터쉐드 변환을 이용하여 3차원 얼굴 모델을 구성하는 방법을 제안한다. 워터쉐드 변환으로 분할된 각각의 영역으로부터 얼굴의 특징점들을 추출하고 MPEG-4에서 정의해놓은 FDP(Facial Definition Parameter)를 기반으로 얼굴 메쉬모델을 생성한다. 워터쉐드 변환시 발생하는 영역 기반의 과분할 결과에서 얻어지는 정확한 정보와 MPEG-4의 FDP를 기반으로 한 Candide Model을 이용함으로써 매우 간편하게 3D 얼굴 모델을 생성할 수 있고 영상 압축 및 전송에 매우 효율적으로 이용될 수 있다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2022.11a
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• pp.42-43
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• 2022

본 논문은 모바일 단말에서 실시간으로 동작하는 딥러닝 기반 경량 초고해상화 기술에 관한 내용이다. 대용량 3차원 메쉬 모델의 비실시간 압축은 실시간 스트리밍 응용 시나리오에서 제약점으로 작용하고 있고, 본 논문에서는 두 입력 텐서의 차원을 일치시켜야 하는 element-wise 덧셈 대신 concatenation을 활용해 연산량을 개선하고, float-to-int8 양자화 과정에서 발생하는 오차를 줄이기 위해 weight clipping 및 regularization 기법을 활용해 초고해상화 화질 성능을 개선하였다. 제안하는 알고리즘은 기존 모바일 초고해상화 기술을 화질 측면에서 0.12dB, 처리 속도 측면에서 13.6ms 개선하였고, Mobile AI & AIM 2022 실시간 이미지 초고해상화 대회에서 1등을 수상하였다.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.40 no.3
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• pp.156-163
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• 2003

Most watermarking techniques insert watermarks into transform coefficients in the frequency domain because we can consider robust or imperceptible frequency bands against malicious attacks to remove them. However, parameterization of 3-D data is not easy because of irregular attribution of connectivity information, while 1-I) or 2-D data is regular. In this paper we propose a new watermarking scheme for 3-D polygonal mesh models in the DCT domain. After we generate triangle strips by traversing the 3-D model and transform its vertex coordinates into the DCT domain, watermark signals are inserted into mid-frequency bands of AC coefficients for robustness and imperceptibility. We demonstrate that our scheme is robust against additive random noise, the affine transformation, and geometry compression by the MPEG-4 SNHC standard.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.3
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• pp.307-313
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• 2009

In general, pyroshock is generated from the actuation of separation devices for several stage, fairing, and satellite separation in the flight of a launch vehicle. During these events, transient vibration phenomenon called pyroshock, which shows large acceleration in the high frequency range, occurs and it can result in the malfunction of electronic components which is equipped inside the launch vehicle or satellite. In this paper, mesh washer isolators made out of SMA were introduced for the isolation of pyroshock. One type of isolator primarily used pseudoelastic characteristics of SMA and the other type of isolator used shape memory effect of SMA. For the study of basic load-displacement relationship of each SMA isolator, compressive loading tests were performed and the results showed the capability of the isolator itself. Pyroshock isolation tests were followed and verified the outstanding isolation performance of isolator. In addition, random vibration tests were also performed and checked the dynamic characteristics of each SMA isolator.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.6 s.312
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• pp.36-45
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• 2006

Three-dimensional (3-D) texture coordinates mean the position information of torture segments that are mapped into polygons in a 3-D mesh model. In order to compress texture coordinates, previous works reused the same linear predictor that had already been employed to code geometry data. However, the previous approaches could not carry out linear prediction efficiently since texture coordinates were discontinuous along a coding order. Especially, discontinuities of texture coordinates became more serious in the 3-D mesh model including a non-atlas texture. In this paper, we propose a new scheme to code 3-D texture coordinates using as a texture image rearrangement. The proposed coding scheme first extracts texture segments from a texture. Then, we rearrange the texture segments consecutively along the coding order, and apply a linear prediction to compress texture coordinates. Since the proposed scheme minimizes discontinuities of texture coordinates, we can improve coding efficiency of texture coordinates. Experiment results show that the proposed scheme outperforms the MPEG-4 3DMC standard in terms of coding efficiency.

• Korean Journal of Computational Design and Engineering
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• v.13 no.1
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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.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.10
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• pp.905-911
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• 2007

In this paper, geometrically and materially non-linear finite element analyses were performed to study the crease behavior of thin membranes. The cross-section of the membrane was modeled with 2-dimensional plane strain elements. To simulate the creasing process, the membrane mesh was folded, compressed to prescribed crease gauge by activating two rigid contact surfaces, and then released to give the crease topology. Various crease gauges were considered to investigate the effect of crease intensity on the initial deployment angle. The crease geometry was also obtained by experiments and the results were compared.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.3
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• pp.417-429
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• 1998

The advance of the MPEG (Moving Picture Expert Group) and the DSP (Digital Signal Processing) technologies lead the emergence of the information appliances, which are gradually digitalized and embedded the high-speed networking function. However, there are some difficulties in establishing any one specific model, since standardization of the scale and function of home ATM network is being progressed by standardization organizations and no absolute model has been defined. This paper consider topologies for a home ATM network, such a star-type, tree-type, and mesh-type topology, by comparing the structure, functional characteristics and performance. From this analysis we suggest the design method of the home ATM network.