• Title/Summary/Keyword: overlapping error

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A Study on Error Verification of STL Format for Rapid Prototyping System (급속조형 시스템을 위한 STL 포맷의 오류 검증에 관한 연구)

  • Park, H.T.;Lee, S.H.
    • Journal of the Korean Society for Precision Engineering
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    • v.13 no.10
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    • pp.46-55
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    • 1996
  • As industrial standard data, the STL format which approximates three dimensional CAD model to triangular facets, is used for RP(Rapid Prototyping) system in recent days. Because most RP system take the only form of two dimensional line segments as an input stream inspite of its imperfectness while converting into STL format, a CAD model is converted into a standard industrial format which is composed of many triangular facets. The error verifying process is composed of four main steps, and these are 1) Remove facets with two or more vertices equal to each other. 2) Fix overlapping error such as more than three facets adjacent to anedge. 3) Fill holes in the mesh by using Delaunay triangulation method. 4) Correct the wrong direction and normal vectors. This paper is concerned with serching the mentioned errors in advance and modifying them.

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PROBE FEEDING SIMULATION USING OVERLAPPING-GRID TECHNIQUE FOR FDTD

  • Min, Kyeong-Sik;Vu, Manh-Dat
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • pp.442-447
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    • 2005
  • This paper presents an application of overlapping-grid technique for probe feeding simulation. The overlapping grid technique is used to solve contour path problem. In this technique, field interpolation is very important to make communication between two coordinates. By applying overlapping-grid technique, error of contour path in probe feeding simulation is reduced.

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A Study on Error Verification of STL format for Rapid Prototyping System (급속조형시스템을 위한 STL 포멧의 오류 검증에 관한 연구)

  • 최홍태;이석희
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.597-601
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    • 1996
  • Nowadays, the STL format, industrial standard data, which approximates three dimensional CAD model to triangular facets, is used for RP(Rapid Prototyping) system. Because most RP machine is accpted to only two dimensional line segments, but some STL translators are sometimes poorly implemented. The error verifying process is as follows. 1) Remove facets with two or more vertices equal to each other. 2) Fix overlapping error such as more than three facets adjacent to an edge. 3) Fill holes in the mesh by using Delaunay triangulation method. 4) Repair wrong direction and value of normal vectors. This paper is concerned with searching the mentioned errors in advance and modifying them.

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Infra-Red Reflectography Based Mural Underdrawing Mosaicing Technique (적외선 리플렉토그래피 기반 벽화 밑그림 영상 모자익 기법)

  • Lee, Tae-Seong;Gwon, Yong-Mu;Go, Han-Seok
    • Proceedings of the KIEE Conference
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    • pp.191-194
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    • 2003
  • In this paper, we propose a new accurate and robust image mosaic technique of the mural underdrawing taken from the infra-red camera, which is based on multiple image registration and adaptive blending technique. The image mosaicing methods which have been developed so far have the following deficits. It is hard to generate a high resolution image when there are regions that do not have features or intensity gradients, and there is a trade-off in overlapping region site in view of registration and blending. We consider these issues as follows. First, in order to mosaic Images with neither noticeable features nor intensity gradients, we use a Projected supplementary pattern and pseudo color image for features in the image Pieces which are registered. Second, we search the overlapping region size with minimum blending error between two adjacent images and then apply blending technique to minimum error overlapping region. Finally, we could find our proposed method is more effective and efficient for image mosaicing than conventional mosaic techniques and also is more adequate for the application of infra-red mural underdrawing mosaicing. Experimental results show the accuracy and robustness of the algorithm.

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An overlapping decomposed filter for INS initial alignment (관성항법장치의 초기정렬을 위한 중복 분해 필터)

  • 박찬국;이장규
    • 제어로봇시스템학회:학술대회논문집
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    • pp.136-141
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    • 1991
  • An Overlapping Decomposed Filter(ODF) accomplishing an initial alignment of an INS is proposed in this paper. The proposed filter improves the observable condition and reduces the filtering computation time. Its good performance has been verified by simulation. Completely observable and controllable conditions of INS error model derived from psi-angle approach are introduced under varying sensor characteristics vary. The east components of gyro and accelerometer have to be the first order markov process and the rest of them are the characteristics of the random walk or first order markov process.

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On the Practical Physical-Layer Network Coding with Partially Overlapped Packets (부분 패킷 중첩 환경에서 물리계층 네트워크 코딩에 관한 연구)

  • Lim, Hyeonwoo;Jung, Bang Chul;Ban, Tae-Won;Sung, Kil-Young
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.19 no.12
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    • pp.2813-2819
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    • 2015
  • In this paper, we investigate the physical layer network coding (PNC) technique in a two-way relay channel (TWRC) where two source nodes send and receive data with each other via a relay node. In particular, we consider the communication scenario where packet length from the two sources is different from each other. We analyze the bit error rate (BER) of the received packet at the relay node according to degree of overlapping between two packets. The BER of the short packet remains unchanged regardless of the degree of overlapping since the entire packet is overlapped with the longer packet, while the BER of the longer packet becomes improved as the degree of overlapping decreases. Thus, we need a novel transmission scheme to enhance BER performance of the PNC technique in TWRC environments since the overall BER performance of the PNC technique at the relay node depends on the worse BER between two ovelapping packets' BERs.

Multi-Rate and Multi-BEP Transmission Scheme Using Adaptive Overlapping Pulse-Position Modulator and Power Controller in Optical CDMA Systems

  • Miyazawa Takaya;Sasase Iwao
    • Journal of Communications and Networks
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    • v.7 no.4
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    • pp.462-470
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    • 2005
  • We propose a multi-rate and multi-BEP transmission scheme using adaptive overlapping pulse-position modulator (OPPM) and optical power controller in optical code division multiple access (CDMA) networks. The proposed system achieves the multi-rate and multi-BEP transmission by accommodating users with different values of OPPM parameter and transmitted power in the same network. The proposed scheme has advantages that the system is not required to change the code length and number of weight depending on the required bit rate of a user and the difference of bit rates does not have so much effect on the bit error probabilities (BEPs). Moreover, the difference of transmitted powers does not cause the change of bit rate. We analyze the BEPs of the four multimedia service classes corresponding to the com­binations of high/low-rates and low/high-BEPs and show that the proposed scheme can easily achieve distinct differentiation of the service classes with the simple system configuration.

Adjusting the Retry Limit for Congestion Control in an Overlapping Private BSS Environment

  • Park, Chang Yun
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.8 no.6
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    • pp.1881-1900
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    • 2014
  • Since 802.11 wireless LANs are so widely used, it has become common for numerous access points (APs) to overlap in a region, where most of those APs are managed individually without any coordinated control. This pattern of wireless LAN usage is called the private OBSS (Overlapping Basic Service Set) environment in this paper. Due to frame collisions across BSSs, each BSS in the private OBSS environment suffers severe performance degradation. This study approaches the problem from the perspective of congestion control rather than noise or collision resolution. The retry limit, one of the 802.11 attributes, could be used for traffic control in conjunction with TCP. Reducing the retry limit causes early discard of a frame, and it has a similar effect of random early drops at a router, well known in the research area of congestion control. It makes the shared link less crowded with frames, and then the benefit of fewer collisions surpasses the penalty of less strict error recovery. As a result, the network-wide performance improves and so does the performance of each BSS eventually. Reducing the retry limit also has positive effects of merging TCP ACKs and reducing HOL-like blocking time at the AP. Extensive experiments have validated the idea that in the OBSS environment, reducing the retry limit provides better performance, which is contrary to the common wisdom. Since our strategy is basically to sacrifice error recovery for congestion control, it could yield side-effects in an environment where the cost of error recovery is high. Therefore, to be useful in general network and traffic environments, adaptability is required. To prove the feasibility of the adaptive scheme, a simple method to dynamically adjust the value of the retry limit has been proposed. Experiments have shown that this approach could provide comparable performance in unfriendly environments.

Multispectral Mural Underdrawing Mosaic Technique (다중스펙트럼 기반 벽화 밑그림 영상 모자익 기법)

  • 이태성;권용무;고한석
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.41 no.5
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    • pp.175-183
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    • 2004
  • In this paper, we propose a new accurate and robust image mosaic technique of the mural underdrawing taken from the infra-red camera, which is based on multiple image registration and adaptive blending technique. The image mosaicing methods which have been developed so far have the following deficits. It is hard to generate a high resolution image when there are regions that do not have features or intensity gradients, and there is a trade-off in overlapping region size in view of registration and blending. We consider these issues as follows. First, in order to mosaic images with neither noticeable features nor intensity gradients, we use a projected supplementary pattern and pseudo color image for features in the image pieces which are registered. Second, we search the overlapping region size with minimum blending error between two adjacent images and then apply blending technique to minimum error overlapping region. Finally, we could find our proposed method is more effective and efficient for image mosaicing than conventional mosaic techniques and also is more adequate for the application of infra-red mural underdrawing mosaicing. Experimental results show the accuracy and robustness of the algorithm

A Quantizer Reconstruction Level Control Method for Block Artifact Reduction in DCT Image Coding (양자화 재생레벨 조정을 통한 DCT 영상 코오딩에서의 블록화 현상 감소 방법)

  • 김종훈;황찬식;심영석
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.28B no.5
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    • pp.318-326
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    • 1991
  • A Quantizer reconstruction level control method for block artifact reduction in DCT image coding is described. In our scheme, quantizer reconstruction level control is obtained by adding quantization level step size to the optimum quantization level in the direction of reducing the block artifact by minimizing the mean square error(MSE) and error difference(EDF) distribution in boundary without the other additional bits. In simulation results, although the performance in terms of signal to noise ratio is degraded by a little amount, mean square of error difference at block boundary and mean square error having relation block artifact is greatly reduced. Subjective image qualities are improved compared with other block artifact reduction method such as postprocessing by filtering and trasform coding by block overlapping. But the addition calculations of 1-dimensional DCT become to be more necessary to coding process for determining the reconstruction level.

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