• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.502-504
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• 1995

In video image compression, it is important to extract the exact notion information from image sequence in order to perform the data compression, the field rate conversion, and the motion compensated interpolation effectively. It is well known that the location of the smallest sum of absolute difference(SAD) does not always give the true motion vector(MV) since the MV obtained via full block search is often corrupted by noise. In this paper, we first classifies the input blocks into 3 categories : the background, the shade-motion, and the edge-motion. According to the characteristics of the classified blocks, multiple locations of relatively small SAD are searched with an adaptive search window by using the proposed method. The proposed method picks MVs among those candidates by using temporal correlation. Since temporal correlation reveals the noise level in a particular region of the video image sequence, we are able to reduce the search are very effectively.

• Journal of Sensor Science and Technology
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• v.21 no.3
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• pp.211-216
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• 2012

Fires are the most common disaster and early fire detection is of great importance to minimize the consequent damage. Simple sensors including smoke detectors are widely used for the purpose but they are able to sense fires only at close proximity. Recently, due to the rapid advances of relevant technologies, vision-based fire sensing has attracted growing attention. In this paper, a novel visual sensing technique to automatically detect fire is presented. The proposed technique consists of multiple steps of image processing: pixel-level, block-level, and frame level. At the first step, fire flame pixel candidates are selected based on their color values in YIQ space from the image of a camera which is installed as a vision sensor at a fire scene. At the second step, the dynamic parts of flames are extracted by comparing two consecutive images. These parts are then represented in regularly divided image blocks to reduce pixel-level detection error and simplify following processing. Finally, the temporal change of the detected blocks is analyzed to confirm the spread of fire. The proposed technique was tested using real fire images and it worked quite reliably.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.3C
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• pp.257-263
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• 2003

Error control and concealment in video communication is becoming increasingly important because transmission errors can cause single or multiple loss of macroblocks in video delivery over unreliable channels such as wireless networks and the internet. This paper describes a temporal error concealment by postprocessing. Lost image blocks are overlapped block motion compensated (OBMC) using median of motion vectors from adjacent blocks at the decoder. The results show a significant improvement over zero motion error concealment and other temporal concealment methods such as Motion Vector Rational Interpolation or Side Match Criterion OBMC by 1.4 to 3.5㏈ gain in PSNR. We present experimental results showing improvements in PSNR and computational complexity.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.9
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• pp.685-689
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• 2009

Flash memory has several features such as low~power consumption and fast access so that there has been various research on using flash memory as new storage. Especially the Solid State Disk which is composed of flash memory chips has recently replaced the hard disk. At present, SSD adopts the multi-channel and multi-way architecture to exploit advantages of parallel access. In this architecture, data are written on SSD in a unit of a superblock which is composed of multiple blocks in which some blocks are put together. This paper proposes two schemes of selecting, segmenting and re-composing victim superblocks to optimize concurrent processing when a buffer flush occurs. The experimental results show that 35% of superblock- based write operations is reduced by selecting victims and additional 9% by composition of superblock.

• Geomechanics and Engineering
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• v.11 no.6
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• pp.787-803
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• 2016

DDARF (Discontinuous Deformation Analysis for Rock Failure) is a numerical algorithm for simulating jointed rock masses' discontinuous deformation. While its reinforcement simulation is only limited to end-anchorage bolt, which is assumed to be a linear spring simply. Here, several new reinforcement modes in DDARF are proposed, including lining reinforcement, full-length anchorage bolt and equivalent reinforcement. In the numerical simulation, lining part is assigned higher mechanical strength than surrounding rock masses, it may include multiple virtual joints or not, depending on projects. There must be no embedding or stretching between lining blocks and surrounding blocks. To realize simulation of the full-length anchorage bolt, at every discontinuity passed through the bolt, a set of normal and tangential spring needs to be added along the bolt's axial and tangential direction. Thus, bolt's axial force, shearing force and full-length anchorage effect are all realized synchronously. And, failure criterions of anchorage effect are established for different failure modes. In the meantime, from the perspective of improving surrounding rock masses' overall strength, a new equivalent and tentative simulation method is proposed, it can save calculation storage and improve efficiency. Along the text, simulation algorithms and applications of these new reinforcement modes in DDARF are given.

• Wind and Structures
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• v.19 no.6
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• pp.585-601
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• 2014

The effect of multiple roughness changes close to a building site was examined through three dimensional computational fluid dynamics (CFD) simulations conducted in a virtual boundary layer wind tunnel (V-BLWT). The results obtained were compared with existing wind speed models, namely ESDU-82026 and Wang and Stathopoulos (WS) model. The latter was verified by wind tunnel tests of sixty nine cases of multiple roughness patches, and also with a simplified 2D numerical model. This work extends that numerical study to three dimensions and also models roughness elements explicitly. The current numerical study shows better agreement with the WS model, that has shown better agreements with BLWT tests, than the ESDU model. This is in contrast to previous results of Wang and Stathopoulos, who concluded that CFD shows better agreement with the ESDU model. Many cases were simulated in a V-BLWT that has same dimensions as BLWT used in the original experiment and also in a reduced symmetrical version (S-BLWT) that takes advantage of regular arrangement of roughness blocks. The S-BLWT gives results almost identical to V-BLWT simulations, while achieving significant reduction on computational time and resources.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.10
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• pp.98-103
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• 1997

Given the small bit allocation for motion information in very low bit-rate coding, motion estimation using the block matching algorithm(BMA) fails to maintain an acceptable level of prediction errors. The reson is that the motion model, or spatial transformation, assumed in block matching cannot approximate the motion in the real world precisely with a small number of parameters. In order to overcome the drawback of the conventional block matching algorithm, several triangle-based methods which utilize triangular patches insead of blocks have been proposed. To estimate the motions of image sequences, these methods usually have been based on the combination of optical flow equation, affine transform, and iteration. But the compuataional cost of these methods is expensive. This paper presents a fast motion estimation algorithm using a multiple linear regression model to solve the defects of the BMA and the triange-based methods. After describing the basic 2-D triangle-based method, the details of the proposed multiple linear regression model are presented along with the motion estimation results from one standard video sequence, representative of MPEG-4 class A data. The simulationresuls show that in the proposed method, the average PSNR is improved about 1.24 dB in comparison with the BMA method, and the computational cost is reduced about 25% in comparison with the 2-D triangle-based method.

• International conference on construction engineering and project management
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• 2024.07a
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• pp.224-230
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• 2024

This study investigates the corrosion rate measurements for multiple reinforcements in concrete by using the galvanostatic pulse technique. In order to know whether or not this technique can distinguish corrosion status for multiple reinforcements covered by the guard ring, two programs were conducted. For the first stage, a reinforcement was embedded in two concrete blocks and the part of reinforcement in one of the block was in a corrosion environment while another part of reinforcement in another block was not in a corrosion environment. Results reconfirmed that the galvanostatic pulse technique detected the local corrosion current owing to the help from guard ring. For the second stage, two parallel reinforcements (one epoxy-coated reinforcement and one plain reinforcement) were embedded in a chloride contaminated concrete block. Results showed that when two reinforcements were covered by guard ring, the galvanostatic pulse technique could not distinguish the corrosion current for each individual reinforcement and an average value would be obtained. In such a case, for the reinforcement which was not corroded one may overestimate its corrosion rate, and for the reinforcement which was corroded one may underestimate its corrosion. Therefore, results imply that a C-scan method (which is commonly used for the ultrasonic testing) may be required to obtain a correct measurement of corrosion rate.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.11
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• pp.955-962
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• 2016

In recent years, there have been emerging needs for standardized software-based motion application development for better scalability and support for multiple operation modes for small quantity batch production. Although a software-based motion system provides a basis for constructing multiple operation modes on a machine, it is not easy to construct such systems without tools for defining multiple motion operation modes and standardized mode-change protocols. This paper proposes a motion recipe concept to overcome this problem; the concept includes the authoring of multiple motion operation modes using the PLCopen-compliant motion function blocks and communication protocols to trigger operation mode changes from an external interface. The motion recipe was implemented by extending an IEC 61131-3 compliant IDE called Beremiz, and the correctness of the motion recipe-based application behavior was verified on a real testbed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5C
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• pp.536-541
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• 2007

In video coding standard H.264/AVC, motion estimation using multiple reference pictures improves compression efficiency but the efficiency depends upon image content not the number of reference pictures. So, the motion estimation includes a large amount of computation of no worth according to image. This paper proposes fast motion estimation algorithm that removes worthless computation in the motion estimation using multiple reference pictures. The proposed algorithm classifies a block into valid and invalid blocks for the multiple reference pictures and removes the workless computation by applying a single reference picture to the invalid block. To estimate the proposed algorithm's performance, image quality, bit rate, and motion estimation time are compared with ones of the conventional algorithm in the reference software JM 9.5. The simulation results show that the proposed algorithm can considerably save about 38.67% the averaged motion estimation time while keeping the image quality and the bit rate, whose are average values are -0.02dB and -0.77% respectively, as good as the conventional algorithm.