• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.803-804
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• 2008

In this paper, we propose an edge dependent interpolation (EDI) method based on adaptive search range. The proposed EDI method uses the vector matching to determine the edge direction, and the vector matching process is terminated when the previous sum of absolute difference (SAD) is smaller than the next one. The adaptive search range method enables the EDI algorithm to estimate edge direction more accurately and to reduce the computational complexity. The experimental results show that the proposed method produces better performance than conventional algorithms.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.2
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• pp.137-144
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• 2008

In this paper, a novel voltage-controlled oscillator(VCO) using the output matching network based on the harmonic control circuit is presented for improving the phase noise property. The phase noise suppression is achieved through the harmonic control circuit having the short impedances for both second-harmonic and third-harmonic components, which has been connected at the output matching network. Also, we have used the microstrip square open loop multiple split-ring resonator(OLMSRR) having the high-Q property to further reduce the phase noise of VCO. Because the output matching network based on the harmonic control circuit has been used for reducing the phase noise property instead of the High-Q resonator, we can obtain the broad tuning range by the low-Q resonator. The phase noise of the proposed VCO using the output matching network based on the harmonic control circuit and the microstrip square OLMSRR has been $-127.5{\sim}126.33$ dBc/Hz @ 100 kHz in the tuning range, $5.744{\sim}5.839$ GHz. Compared with the reference VCO using the output matching network without the harmonic control circuit and the microstrip line resonator, the phase noise property of the proposed VCO has been improved in 26.66 dB.

• Journal of IKEEE
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• v.9 no.1 s.16
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• pp.19-30
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• 2005

Packet classification is defined as the action to match the packet with a set of predefined rules. One of classification is to use Ternary Content Addressable Memory hardware search engine that has faster than other algorithmic methods. However, TCAM has some limitations. One of them is that TCAM can not perform range matching efficiently. A range has to be expanded into prefixes to fit the boundary. In general, the number of expansion could be up to 2w-2, where w is the width of the field. For example, if two range fields with 16 bits are used, there could be up to $30\;{\times}\;30\;=\;900$ expansions for a single rule. In this paper, we describe the novel algorithm for converting range matching rules into TCAM entry efficiently. The number of maximum entry is 2w-4 when using the algorithm. Furthermore, it has also benefit about the negation range. In the result of experimentation, the new scheme practically reduces 14 percent in case that searched fields are source port and destination port number.

• The KIPS Transactions:PartA
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• v.12A no.2 s.92
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• pp.87-94
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• 2005

Pattern matching is one of critical parts of Network Intrusion Prevention Systems (NIPS) and computationally intensive. To handle a large number of attack signature fattens increasing everyday, a network intrusion prevention system requires a multi pattern matching method that can meet the line speed of packet transfer. In this paper, we analyze Snort, a widely used open source network intrusion prevention/detection system, and its pattern matching characteristics. A multi pattern matching method for NIPS should efficiently handle a large number of patterns with a wide range of pattern lengths and case insensitive patterns matches. It should also be able to process multiple input characters in parallel. We propose a multi pattern matching hardware accelerator based on Shift-OR pattern matching algorithm. We evaluate the performance of the pattern matching accelerator under various assumptions. The performance evaluation shows that the pattern matching accelerator can be more than 80 times faster than the fastest software multi-pattern matching method used in Snort.

• Korean Journal of Construction Engineering and Management
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• v.5 no.5 s.21
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• pp.151-162
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• 2004

Current methods for construction site modeling employ large, expensive laser range scanners that produce dense range point clouds of a scene from different perspectives. Days of skilled interpretation and of automatic segmentation may be required to convert the clouds to a finished CAD model. The dynamic nature of the construction environment requires that a real-time local area modeling system be capable of handling a rapidly changing and uncertain work environment. However, in practice, large, simple, and reasonably accurate embodying volumes are adequate feedback to an operator who, for instance, is attempting to place materials in the midst of obstacles with an occluded view. For real-time obstacle avoidance and automated equipment control functions, such volumes also facilitate computational tractability. In this research, a human operator's ability to quickly evaluate and associate objects in a scene is exploited. The operator directs a laser range finder mounted on a pan and tilt unit to collect range points on objects throughout the workspace. These groups of points form sparse range point clouds. These sparse clouds are then used to create geometric primitives for visualization and modeling purposes. Experimental results indicate that these models can be created rapidly and with sufficient accuracy for automated obstacle avoidance and equipment control functions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.8B
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• pp.745-756
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• 2006

The general packet filtering system using TCAM has some limitations such as range and negation rules filtering, so this paper proposes efficient searching schemes than existing methods. CRG(Converting Range rules using Gray code) algorithm, in the case of range rules, that takes advantage of the gray code and TCAM characteristics to save a number of TCAM entries is proposed, and a nTCAM(TCAM with negation) architecture for negation rules is proposed, implemented using a FPGA design tool, and verified through the wave simulation. According to the simulation with the SNORT rules, the CRG algorithm and nTCAM save TCAM entries about 93% in IPv4 and 98% in IPv6 than the existing method.

• ETRI Journal
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• v.34 no.1
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• pp.87-97
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• 2012

This study presents an automatic matching method for generating a dense, accurate, and discontinuity-preserved digital surface model (DSM) using multiple images acquired by an aerial digital frame camera. The proposed method consists of two main procedures: area-based multi-image matching (AMIM) and stereo-pair epipolar line matching (SELM). AMIM evaluates the sum of the normalized cross correlation of corresponding image points from multiple images to determine the optimal height of an object point. A novel method is introduced for determining the search height range and incremental height, which are necessary for the vertical line locus used in the AMIM. This procedure also includes the means to select the best reference and target images for each strip so that multi-image matching can resolve the common problem over occlusion areas. The SELM extracts densely positioned distinct points along epipolar lines from the multiple images and generates a discontinuity-preserved DSM using geometric and radiometric constraints. The matched points derived by the AMIM are used as anchor points between overlapped images to find conjugate distinct points using epipolar geometry. The performance of the proposed method was evaluated for several different test areas, including urban areas.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.37 no.4
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• pp.16-25
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• 2000

In this paper, a new disparity detection algorithm which is robust to noise is presented. It detects the disparity of an arbitrary pixel through the iterative competition with neighbor pixels in the range of disparity. A diffusion process to improve stereo matching confidence is used prior to detecting disparity of an arbitrary pixel. It is used for aggregating initial matching measure of the difference map. If the image region for matching is too small, a wrong match might be found due to noise. On the contrary, the region is too big, it results in blurring of object boundaries. Therefore, we decide the image region for matching by using the diffusion process for aggregating matching measure, then detect the true disparity with proposed competition method to the distribution of matching measure. Through the proposed method we get the result of improving matching rate of 6.96% with real stereo imge. From the simulation with the stereo imge, the proposed disparity detection method significantly outperforms the conventional method to matching rate.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.99-102
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• 2009

In this paper a hierarchical stereo matching algorithm based on feature extraction is proposed. The boundary (edge) as feature point in an image is first obtained by segmenting an image into red, green, blue and white regions. With the obtained boundary information, disparities are extracted by matching window on the image boundary, and the initial disparity map is generated when assigned the same disparity to neighbor pixels. The final disparity map is created with the initial disparity. The regions with the same initial disparity are classified into the regions with the same color and we search the disparity again in each region with the same color by changing block size and search range. The experiment results are evaluated on the Middlebury data set and it show that the proposed algorithm performed better than a phase based algorithm in the sense that only about 14% of the disparities for the entire image are inaccurate in the final disparity map. Furthermore, it was verified that the boundary of each region with the same disparity was clearly distinguished.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2010.04a
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• pp.23-25
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• 2010

In this paper, we studied linking method for updating navigation map with new address map. This method is hierarchical as we chose candidate using attribute data for geometry matching. Limiting a matching range, we conducted a experiment ICP with geometry matching. As a result, for linking method it's quite satisfied but for updating method, we decided that we have to do more precise method for updating.