• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.6
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• pp.1554-1561
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• 1998

When the superposition of realtime traffic and non-realtime traffic is applied to the ATM network, the successive cell loss(block loss) is more influential on the quality of service (QoS) of two traffic streams than the single loss in case of bursty traffic. Block loss can be identified as an important performance measure because of delay-oriented policy for realtime traffic. In this paper, we consider the system with the two-level overload control reducing of the recurrence of shut-down periods and develop a recursive algorithm to obtain both block loss and cell loss probabilities of both traffic. We can see that it gives the more precise and diverse investigations on performance analysis of queuing strategy.

• Journal of KIISE:Software and Applications
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• v.32 no.1
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• pp.22-33
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• 2005

In this paper. we propose an image registration algorithm based on variable-sized blocks of ellipsoidal prototype model which is similar in shape to human face. While matching blocks, the existing cylindrical prototype model which only takes into account left and right curvature can accomplish a correct alignment on left and right images. But, registration errors are produced from up and down images because the cylindrical prototype model not reflects characteristics of head shape and jaw structure of human. The proposed method is a block matching algorithm which uses variable-sized blocks with considering left-right and up-down curvature of ellipsoidal face model and can correctly align images by using the correlation between them. We then adapt image mosaic technique to generate a face texture from aligned images. For this purpose, we stitch them with assigning linear weights according to the overlapped region and remove ghost effects to make more realistic facial texture.

• Journal of Biomedical Engineering Research
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• v.18 no.4
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• pp.397-407
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• 1997

In this paper, we present a signal analysis environment with visual programming capability, which is called Signal Analysis and Visualization Environment( SAVE). The system allows a user to perform visually programmed analysis of signals and visualize the results. The visualization facility enables the user to compare original signals with processed ones arid also to display signals overlaid synchronously with the events extracted from the signals. The SAVE system has an extensible architecture: each signal processing algorithm is implemented as a separate building block object module, which can be freely added or removed from the SAVE system without any code modification. We describe the overall structure of the SAVE system and the building block objects, which provide the extensibility in collaboration with together. We illustrate some test runs in order to five a taste of how to use and where to use the system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.11 s.114
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• pp.1065-1072
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• 2006

An OFDM(Orthogonal Frequency Division Multiplexing) system has the problem of the PAPR(Peak-to-Average Power Ratio) due to the overlapping phenomena of many sub-carriers. The previously proposed GA-SPW(Genetic Sub-block Phase Weighting) method not only improved the reduction of PAPR as the number of sub-blocks increases in an OFDM symbol but also decreased the number of calculations involved in the iterative phase searching yields to depend on the number of population and generation by using genetic algorithm not on the number of sub-blocks and phase elements. In this paper, we propose the modified GA-SPW method in order to improve the performance and to decrease the complexity. It is shown that the proposed modified GA-SPW method achieves the significant performance and the reduction of search complexity comparing to the ordinary technique, iterative flipping and previously proposed GA-SPW by the experimental results and analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1B
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• pp.167-174
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• 2000

The three-step search(TSS) algorithm, a simple and gradual motion estimation algorithm, has been widely used in some low bit-rate video compression. We propose a new fast block motion estimation algorithm using the characteristics of motion in search region. Most of motion vectors exist in the center region of search area, so the notion in that region is examined more closely than TSS in this paper. Also in a search step, motion vector is estimated in the local area which is not overlapped with the search area in previous step, considering the all possible direction of motion. Therefore, we get the better motion estimation and reduce computational time in compared with the conventional methods.

• Convergence Security Journal
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• v.18 no.4
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• pp.3-10
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• 2018

Each online user should perform a separate registration and manage his ID and password for each online commerce or SNS service. Since a common secret is shared between the user and the SNS server, the server compromise induces the user privacy breach and financial loss. In this paper, it is considered that the user's authentication material is shared between multiple SNS servers for user authentication. A blockchain service architecture based on Hyperledger Fabric is proposed for each user to utilize an identical ID and OTP using the enhanced hash-chain-based OTP.

• The KIPS Transactions:PartB
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• v.11B no.6
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• pp.661-666
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• 2004

In the wireless communication systems, transmission errors degrade the reconstructed image quality severely. Error 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 internet. Among various techniques which can reduce the degradation of video quality, the error concealment techniques yield good performance without overheads and the modification of the encoder. In this paper, lost image blocks can be concealed with the OBMC(Overlapped Block Motion Compensation) after new motion vectors of the lost image blocks are allocated by median values using the adaptive selection with motion vectors of adjacent blocks. We know our algorithm is more effective in case of continuous GOB loss. The results show a significant improvement over the zero motion error concealment and other temporal concealment methods such as Motion Vector Rational Interpolation or Median＋OBMC by 3dB gain in PSNR.

• Journal of IKEEE
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• v.17 no.4
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• pp.459-468
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• 2013

Under nonlinear characteristics of frames, we propose the frame interpolation using GRNN to enhance the visual picture quality. By full search with block size of 128x128~1x1 to reduce blocky artifact and image overlay, we select the frame having block of minimum error and re-estimate the nonlinear moving vector using GRNN. We compare our scheme with forward(backward) motion compensation, bidirectional motion compensation when the object movement is large or the object image includes zoom-in and zoom-out or camera focus has changed. Experimental results show that the proposed method provides better performance in subjective image quality compared to conventional MCFI methods.

• Journal of the Korea Society of Computer and Information
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• v.28 no.5
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• pp.49-56
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• 2023

Currently, e-commerce is changing from a digital twin to a metaverse world. The metaverse world is an intermediate form between virtual and real worlds and is operated as a coin-based meta-commerce. In this meta-commerce world, blockchain-based NFT coins are used when trading items (contents). In this study, we studied how to issue a large number of NFT coins (certification) rather than issuing a single type of NFT. The research method was designed to produce content layer-based and automatically create the desired quantity using a mass NFT index and automatic generation method. In this study, a layer overlap method (background, body, etc.) was used with a Phyton-based program for mass minting. As a result, it can be used as a blockchain-based certificate that can prove a group of many people. In addition, the content created with the NFT index was registered on the NFT sales site to confirm its utilization and value.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.92-92
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• 2016

전기방전의 기본적인 특성을 가지고 있는 플라즈마를 이용하여 재료를 가공하는 증착, 식각, 표면처리 공정에 있어서 플라즈마 내의 전자 충돌 반응에 의한 이온, 라디칼의 생성과 재료 표면의 반응을 분석하는 도구로써 분압 측정은 일반적인 화학 조성 분석에 기원한 오랜 역사를 가지고 있다. 1 amu 정도의 분해능을 가지고 있고 크기가 30 cm 정도에 불과한 사중극자 질량 분석기는 적절한 질량 스캔 시간과 넓은 이온 전류 측정 범위를 가지므로 소형 차등 배기 시스템과 조합하면 1 mTorr 영역의 스퍼터링 시스템에서 1 Torr 영역의 PECVD/PEALD 시스템 진단에도 쉽게 적용이 가능하다. Inficon사의 CPM-300과 Pfeiffer사의 Prisma80을 이용한 플라즈마 식각 공정 분석 결과를 보면 동위원소까지 분석이 가능하다. 또한 전자충돌 이온화 에너지를 조절하여 m/q(질량전하비율)가 중첩되는 경우의 해석도 가능하다. 다중 오리피스를 갖는 compact design의 밸브 블록을 이용한 설계에서는 line-of-sight 입사가 불가능하여 이온 전류를 분석할 수 없다는 단점이 있으나 표준 가스를 이용한 정량화 등의 큰 장점들이 있다. 최근 이루어진 연구의 내용으로는 유도 결합 플라즈마 장치에서 전도성 메쉬를 이용한 라디칼 거동 관찰을 위해서 두 대의 CPM-300을 메쉬 전 후에 설치하여 라디칼의 양 변화를 전류 프로브와 같이 사용하여 조사하였다.