• The Journal of the Acoustical Society of Korea
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• v.15 no.2
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• pp.95-100
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• 1996

In this paper, we present an image coder using variable quantizer for newly proposed JPEG extensions which has been standardized as ISO/IEC 10918-3(ITU-T Rec. T.84). It is necessary to alleviate the blocking artifact which is more sensitive to human eye in view of the spatial frequency sensitivity. The blocking artifact arises in the lower activity area rather than in the higher area. Therefore variable quantizer use the horizontal and vertical derivatives for calculating the $8{\times}8$ block activity. We classified nonlinear quantizer parameter into 5 categories in order to finely quantize in the lower active region. As a result of simulation for various images, the proposed coder increases subjective and objective quality at a given bit rate.

• Journal of the Korean Institute of Telematics and Electronics
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• v.22 no.6
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• pp.41-45
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• 1985

A suboptimum block quantization method is investigated for efficent transform coding. In our study the following method has appeared as suboptimum. At first, optimum bit allocation is done assuming the varances of the transform coefficients are known. Secndly, a varance estimation algorithm which results from the approximate equations governing the optimum vit alllocation is applied. The better performance of the proposed block quantization method has been confirmed by simulations based on varous pdf assumptions. the results indicate that the proposed method yields overall improvements of about 25% in NMSE for both the symmetric nonuniform and uniform quantizer at the coding rate of 1 bit/pel.

• Information Display
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• v.21 no.2
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• pp.3-9
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• 2020

• Proceedings of the Optical Society of Korea Conference
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• 1996.09a
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• pp.88-88
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• 1996

• Convergence Security Journal
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• v.6 no.4
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• pp.83-90
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• 2006

In this paper, we propose a new design method for a robust vector quantizer that is independent of the statistical characteristics of input images in the wavelet transformed image coding. The conventional vector quantizers have failed to get quality coding results because of the different statistical properties between the image to be quantized and the training sequence for a codebook of the vector quantizer. Therefore, in order to solve this problem, we used a pseudo image as a training sequence to generate a codebook of the vector quantizer; the pseudo image is created by adding correlation coefficient and edge components to uniformly distributed random numbers. We will clearly define the problem of the conventional vector quantizers, which use real images as a training sequence to generate a codebook used, by comparing the conventional methods with the proposed through computer simulation. Also, we will show the proposed vector quantizer yields better coding results.

• Journal of the Korea Society of Computer and Information
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• v.28 no.3
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• pp.1-9
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• 2023

In this paper, we identify the factors that hinder the application of quantum computing technology to solve meaningful real-world problems, and suggest related research trends and directions. To this end, we summarize the basic knowledge of quantum mechanics from the perspective of computer science, which is necessary to understand the difficulties in applying quantum computing technology, and analyze the currently commercialized quantum computers and quantum programming layers from the literature. Through an analysis of the current status and utilization of cloud-based commercial quantum computing services, we identify four factors that currently hinder the practical application of quantum computing: high barriers to entry for quantum computer programming, constraints on noisy intermediate-scale quantum computers, a still-growing open source ecosystem, and difficulties in simulating realistic problem sizes, and suggest trends and directions for related research. In doing so, it is expected to contribute to laying the groundwork for practical applications of quantum computing technology.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.7 s.337
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• pp.5-12
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• 2005

The device performance of nano-scale center-channel (CC) double-gate (DG) MOSFET structure was investigated by numerically solving coupled Schr$\"{o}$dinger-Poisson and current continuity equations in a self-consistent manner. The CC operation and corresponding enhancement of current drive and transconductance of CC-NMOS are confirmed by comparing with the results of DG-NMOS which are performed under the condition of 10-80 nm gate length. Device optimization was theoretically performed in order to minimize the short-channel effects in terms of subthreshold swing, threshold voltage roll-off, and drain-induced barrier lowering. The simulation results indicate that DG-MOSFET structure including CC-NMOS is a promising candidates and quantum-mechanical modeling and simulation calculating the coupled Schr$\"{o}$dinger-Poisson and current continuity equations self-consistently are necessary for the application to sub-40 nm MOSFET technology.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.289-292
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• 2003

이 논문은 WCDMA 와 안테나 배열 시스템에서 저 레벨 양자화와 MUSIC 알고리즘을 사용하여 신호의 방향을 추정하는 방법을 제안한다. 추가의 Power-Up Function 이 필요 없는 방향각 방법으로 이동가입자의 위치를 알아내기 위해 안테나 배열을 이용하여, WCDMA 시스템에서 역확산 코드로 다수의 신호를 분리하고, 각 신호를 저 레벨로 양자화 시켜 MUSIC 으로 신호의 방향각을 추정하였다. 이 방법을 이용하면 단말기의 안테나 출력파워가 낮더라도 기존 방법의 에러율과 비슷함을 시뮬레이션 결과로 알 수 있고, 양자화 비트를 처리하기 위해 필요한 메모리 또한 줄일 수 있어 하드웨어의 비용을 줄일 수 있을 것이다.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.05a
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• pp.188-191
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• 2021

최근 IBM, Intel 과 같은 글로벌 ICT 기업들과 여러 스타트업들이 양자 컴퓨터 개발에 성공하였으며 그에 따라 양자 시뮬레이터와 컴파일러에 대한 관심이 높아졌다. 여러 개의 시뮬레이터가 존재하는 만큼 시뮬레이터마다 제공하는 기능과 성능 역시 제각각 다르다. 본 논문에서는 비교적 접근이 쉬운 파이썬과 Q# 기반의 대표적인 양자 시뮬레이터 3 가지(Qiskit, Project Q, Quantum Development Kit)에서 제공하는 기능들을 소개하고 시뮬레이션 실행시간을 비교한다. 10 뎁스의 20 큐비트 회로에서는 QDK 시뮬레이터가 0.227 초로 실행 시간이 가장 짧았고, 10 큐비트의 10 뎁스 회로의 경우 Project Q 가, 1000 뎁스의 경우 Qiskit 이 가장 짧은 실행시간으로 측정됐다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.2
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• pp.27-38
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• 2002

A new self-consistent mathematical model for semiconductor quantum well device was developed. The model was based on the direct solution of the Boltzmann transport equation, coupled to the Schrodinger and Poisson equations. The solution yielded the distribution function for a two-dimensional electron gas(2DEG) in quantum well devices. To solve the Boltzmann equation, it was transformed into a tractable form using a Legendre polynomial expansion. The Legendre expansion facilitated analytical evaluation of the collision integral, and allowed for a reduction of the dimensionality of the problem. The transformed Boltzmann equation was then discretized and solved using sparce matrix algebra. The overall system was solved by iteration between Poisson, Schrodinger and Boltzmann equations until convergence was attained.