• Journal of KIISE:Information Networking
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• v.30 no.6
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• pp.695-704
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• 2003

A wavelet-based video stream is more susceptible to the network transmission errors than DCT-based video. This is because bit-errors in a subband of a video frame affect not only the other subbands within the current frame but also the subsequent frames. In this paper, we propose a video source coding scheme called IPC(Intra Prediction Coding) scheme in order to reduce the error propagation to the subsequent frames. In the proposed scheme, a subband except LL subband in the current frame refers to the lower-level subband within the same frame. This reduces the error propagation to subsequent frames. We evaluated the performance of our proposed scheme in the simulated wireless network environment. As a result of tests, it was shown that the proposed algorithm shows better performance than MRME in a heavy motion image sequence while IPC outperforms MRME at a high bit-rate in small motion image sequence.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.1
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• pp.46-56
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• 1991

In this paper, 16word X 8bit Content Addressable and Reentrant Memory(CARM) is described. This device has 4 operation modes(read, write, match, reentrant). The read and write operation of CARM is like that of static RAM, CARM has the reentrant mode operation where the on chip garbage collection is accomplished conditionally. Thus function can be used for high speed matching unit of dynamic data flow computer. And CARM also can encode matching address sequentially according to therir priority. CARM consists of 8 blocks(CAM cell, Sequential Address Encoder(S.A.E). Reentrant operation. Read/Write control circuit, Data/Mask Register, Sense Amplifier, Encoder. Decoder). Designed DARM can be used in data flow computer, pattern, inspection, table look-up, image processing. The simulation is performed using the QUICKSIM logic simulator and Pspice circuit simulator. Having hierarchical structure, the layout was done using the 3{\;}\mu\textrm{m} n well CMOS technology of the ETRI design rule.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.1
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• pp.69-77
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• 1989

A hologram scanner for POS bar code symb9ol readers has been developed. This system is composed of scanning optics, optical detector, video signal circuitary and preprocessor. In contrast to conventional scanners using polygonal mirrors, which complicate the scanning optics, the hologram scanner developed in this research was made up with simple optics and higher reading performance was achieved. And in order to read abar code symbol omnidirectionally with highdensity scan patterns, the new real time decoding technique was proposed. The advantage of this technique is less hardware and lower clock rate. High speed processing and improved readability for tilted symbol was confirmed experimentally.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1903-1913
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• 2016

In this paper, we propose 2-stage beamformer with linear receiver in wireless backhaul downlink system where macro base station has large antenna array with sub-array structure. Also, to compare the system capacity, we apply 3-stage beamformer with zero-forcing precoder and calculate the achievable sum rate of received small cell base stations. Considering scattering and path-loss property of wireless backhaul channel, we combine precoding technique for spatial multiplexing and beamforming technique to overcome path-loss. Therefore, we design DFT-based fixed beam patterns for the first stage. The simulation results show that considering spatial multiplexing, proposed 2-stage beamformer with linear receiver can increase the achievable sum rate as well as reduce the feedback information.

• Journal of Digital Contents Society
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• v.11 no.1
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• pp.17-24
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• 2010

The purpose of this study is to design and implement a kernel for the support vector machine(SVM) to improve the performance of face recognition. Local feature analysis(LFA) has been well known for its good performance. SVM kernel plays a limited role of mapping low dimensional face features to high dimensional feature space but the proposed kernel using LFA is designed for face recognition purpose. Because of the novel method that local face information is extracted from training set and combined into the kernel, this method is expected to apply to various object recognition/detection tasks. The experimental results shows its improved performance.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.3
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• pp.22-28
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• 2010

Adaboost is well known for a representative learner as one of the kernel methods. Adaboost which is based on the statistical learning theory shows good generalization performance and has been applied to various pattern recognition problems. However, Adaboost is basically to deal with a two-class classification problem, so we cannot solve directly a multi-class problem with Adaboost. One-Vs-All and Pair-Wise have been applied to solve the multi-class classification problem, which is one of the multi-class problems. The two methods above are ones of the output coding methods, a general approach for solving multi-class problem with multiple binary classifiers, which decomposes a complex multi-class problem into a set of binary problems and then reconstructs the outputs of binary classifiers for each binary problem. However, two methods cannot show good performance. In this paper, we propose the method to solve a multi-target classification problem by using radial basis function of Adaboost weak classifier.

• The KIPS Transactions:PartC
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• v.13C no.1 s.104
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• pp.19-26
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• 2006

Recently, web server hacking is trending toward web application hacking which uses comparatively vulnerable web applications based on open sources. And, it is possible to hack databases using web interfaces because web servers are usually connected databases. Web application attacks use vulnerabilities not in web server itself, but in web application structure, logical error and code error. It is difficult to defend web applications from various attacks by only using pattern matching detection method and code modification. In this paper, we propose a method to secure the web applications based on profiling which can detect and filter out abnormal web application requests.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1867-1875
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• 2011

In this paper, a low-area 256-point FFT structure is proposed. For low-area implementation CSD(Canonic Signed Digit) multiplier method is chosen. Because multiplication type should be less for efficient CSD multiplier application to the FFT structure, the Radix-$4^2$ algorithm is chosen for those purposes. After, in the proposed structure, the number of multiplication type is minimized in each multiplication block, the CSD multipliers are applied for implementation of multiplication. Furthermore, in CSD multiplier implementation, cell-area is more reduced through common sub-expression sharing(CSS). The Verilog-HDL coding result shows 29.9% cell area reduction in the complex multiplication part and 12.54% cell area reduction in overall 256-point FFT structure comparison with those of the conventional structure.

• Journal of Broadcast Engineering
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• v.23 no.6
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• pp.813-823
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• 2018

UHD content is characterized by higher bandwidth requirements to provide seamless playback. The existing HTTP adaptive streaming scheme periodically requests video segment of lower quality than the available bandwidth in the steady state. In the steady state, the On-Off pattern is repeated due to the difference of the available bandwidth and the encoding rate of the content. And the repeated Off interval is causing the problem that can not efficiently use the available bandwidth. In the wireless environment where the delay and loss rate are higher with large bandwidth fluctuations, this problem is exacerbated because the available bandwidth is estimated inaccurately. Therefore, in this paper, we propose a segment scheduling scheme for efficient bandwidth utilization of UHD contents streaming in wireless environment. Proposed scheme is a group segment that simultaneously reqeusts multiple segments in one request message in order to reduce frequency of OFF interval. Through simulation, Our scheme improves bandwidth utilization.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.4
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• pp.715-722
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• 2019

This paper introduces the implementation of an user-aware system using a visible light communication and its operations. The user-aware system using a visible light communication consists of the transmitter based on the Android system and the receiver based on an open-source controller. In the transmitter, user's personal information data is encoded and converted to visible light signals by the Android camera interface. In the receiver, the photodiode module receives the incoming visible light signals and converts to electrical signals and the open-source controller, that is arduino processes the received data. The processing module finds the start bit of 0111 to determine the user information data from the packet for the burst-mode communication. According to the experimental results, the proposed system successfully transmits and receives visible light data with the manchester encoding.