• 한국멀티미디어학회논문지
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• 제17권11호
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• pp.1279-1285
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• 2014

In this paper, we propose on image encryption method which uses NC(Non-linear Cycle) and 2D CAT(Two-Dimensional Cellular Automata Transform) in sequence to encrypt medical images. In terms of the methodology, we use NC to generate a pseudo noise sequence equal to the size of the original image. We then conduct an XOR operation of the generated sequence with the original image to conduct level 1 NC encryption. Then we set the proper Gateway Values to generate the 2D CAT basis functions. We multiply the generated basis functions by the altered NC encryption image to conduct the 2nd level 2D CAT encryption. Finally, we verify that the proposed method is efficient and extremely safe by conducting an analysis of the key spatial and sensitivity analysis of pixels.

• 대한음성학회지:말소리
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• 제47호
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• pp.85-96
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• 2003

It is difficult to implement sound field effect on real time using linear convolution in time domain because linear convolution needs much multiply operations. In this paper three ways is introduced to reduce multiplication operations. Firstly, linear convolution in time domain is replaced with circular convolution in frequency domain. It means that it operates multiplication in place of convolution. Secondly, one frame will be divided into several frames. It will reduce the multiplication operation in processing that transforms time domain into frequency domain. Finally, QFT will be used in place of FFT. Three ways result much reduction in multiplication operations. The reduction of the multiplication operation makes the real time implementation possible.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.368-370
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• 2001

There are various shapes such as square, rectangular, L, and T type in the grounding systems of substations. IEEE St-d suggests the formula considering the characteristics of the various grounding systems but the final value can not be taken, and them the analysis of complicated computer program for obtaining the more accurate value is needed. In his paper, by using CDEGS(Current, Distribution, Electromagnetic and Soil Structure Analysis) the estimated functions derives form the modification coefficient for each of various types above mentioned. The mesh voltage expected can be obtained without the conventional expensive program using compensating methods that multiply IEEE formula by the estimated function.

• 대한임베디드공학회논문지
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• 제4권1호
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• pp.1-8
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• 2009

This paper proposes a 24-bit floating point multiply and accumulate(MAC) unit that can be used in geometry transformation process in 3D graphics. The MAC unit is composed of floating point multiplier and floating point accumulator. When separate multiplier and accumulator are used, matrix calculation, used in the transformation process, can't use continuous accumulation values. In the proposed MAC unit the accumulator can get continuous input from the multiplier and the calculation time is reduced. The MAC unit uses about 4,300 gates and can be operated at 150 MHz frequency.

• International Journal of Reliability and Applications
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• 제4권1호
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• pp.41-50
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• 2003

This paper represents the first comprehensive comparison of the Newton-Raphson's method and Simple Iterative Procedure (SIP) in the maximum likelihood estimation of the two-parameter Weibull distribution. Computer simulation is employed to compare these two methods for multiply censored, singly censored data (Type I or Type Ⅱ censoring) and complete data. Results indicate the Newton-Raphson's with the Menon's estimated value, as an initial point remains the effective iterative procedure for estimating the parameters.

• 대한수학회보
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• 제58권2호
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• pp.419-431
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• 2021

In this paper we discuss the classical problem of finding conditions on the entire coefficients A(z) and B(z) guaranteeing that all nontrivial solutions of f" + A(z)f' + B(z)f = 0 are of infinite order. We assume A(z) is an entire function of completely regular growth and B(z) satisfies three different conditions, then we obtain three results respectively. The three conditions are (1) B(z) has a dynamical property with a multiply connected Fatou component, (2) B(z) satisfies T(r, B) ~ log M(r, B) outside a set of finite logarithmic measure, (3) B(z) is extremal for Denjoy's conjecture.

• 한국정보통신학회논문지
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• 제25권11호
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• pp.1627-1634
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• 2021

본 논문은 저전력 뉴럴 네트워크 가속기 SOC를 위한 아날로그 Convolution Filter용 저전력 초소형 ADC 회로 및 칩 설계 기술을 소개한다. 대부분의 딥러닝의 학습과 추론을 할 수 있는 Convolution neural network accelerator는 디지털회로로 구현되고 있다. 이들은 수많은 곱셈기 및 덧셈기를 병렬 구조로 구현하며, 기존의 복잡한 곱셉기와 덧셈기의 디지털 구현 방식은 높은 전력소모와 큰 면적을 요구하는 문제점을 가지고 있다. 이 한계점을 극복하고자 본 연구는 디지털 Convolution filter circuit을 Analog multiplier와 Accumulator, ADC로 구성된 Analog Convolution Filter로 대체한다. 본 논문에서는 최소의 칩면적와 전력소모로 Analog Accumulator의 아날로그 결과 신호를 디지털 Feature 데이터로 변환하는 8-bit SAR ADC를 제안한다. 제안하는 ADC는 Capacitor Array의 모든 Capacitor branch에 Split capacitor를 삽입하여 모든 branch의 Capacitor 크기가 균등하게 Unit capacitor가 되도록 설계하여 칩면적을 최소화 한다. 또한 초소형 unit capacitor의 Voltage-dependent capacitance variation 문제점을 제거하기 Flipped Dual-Capacitor 회로를 제안한다. 제안하는 ADC를 TSMC CMOS 65nm 공정을 이용하여 설계하였으며, 전체 chip size는 1355.7㎛², Power consumption은 2.6㎼, SNDR은 44.19dB, ENOB는 7.04bit의 성능을 달성하였다.

• 한국컴퓨터정보학회논문지
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• 제6권2호
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• pp.90-96
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• 2001

네트워크의 발전은 통신망의 발전과 더불어 심각한 사회문제를 발생시킨다. 즉, 보안에 관련된 문제는 네트워크를 사용할 경우 해킹과 크래킹에 대하여 더욱 주의해야 한다는 것이다. 본 논문에서는 키분배 및 키길이에 관한 결정론적 문제점에 무관하게 암호화를 수행할 수 있는 다중 비선형 S-box 함수(Multiple nonlinear S-box function)를 사용하는 블록 암호시스템을 제안하고 하드웨어를 설계하였다. 제안된 다중 비선형 S-box는 암호화에사용되어지는 키 데이터에 대하여 비선형 함수를 다중으로 사용하여 비도를 증가시켰으며DC 및 LC에 의한 암호해석을 방지하기 위하여 MDP, MLP를 최대로 할 수 있도록 하였다. 본 논문에서 제안한 다중 비선형 S-box 함수는 Synopsys Ver. 1999.10과 VHDL을 사용하여 회로합성 및 모의실험을 수행하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1438-1441
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• 2005

To establish of standard technique of nano-length measurement in 2D plane, new AFM system has been designed. In this system, measurement uncertainty is dominantly affected by the Abbe error of XY scanning stage. No linear stage is perfectly straight; in other words, every scanning stage is subject to tilting, pitch and yaw motion. In this paper, an AFM system with minimum offset of XY sensing is designed. And XY scanning stage is designed to minimize rotation angle because Abbe errors occur through the multiply of offset and rotation angle. To minimize the rotation angle optimal design has performed by maximizing the stiffness ratio of motion direction to the parasitic motion direction of each stage. This paper describes the design scheme of full AFM system, especially about XY stage. Full range of fabricated XY scanner is $100um\times{100um}$. And tilting, pitch and yaw motion are measured by autocollimator to evaluate the performance of XY stage. Using this AFM system, 3um pitch specimen was measured. As a result, the uncertainty of total system has been evaluated.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1994년도 가을 학술발표회 논문집
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• pp.356-361
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• 1994

From the previous experimental test results, it has shown that shear that shear strength in lightweight concrete beams was about 85% on that in normal concrete beams. It is speculated that shear connectors in composite beams of steel and lightweight concrete associated with the longitudinal shear strength decrease more in strength than those in normal concrete. So this paper, as a study on strength of shear connectors in composite beams of steel and lightweight concrete slabs, has a purpose to compare the strength formula resulted from the push-out test of thirteen solid slab and four deck Plate slab with the established ones, and then to suggest a proper strength formula of the shear connectors. The established strength formula of the shear connectors is prescribed for $P_ps = 0.50A_s . \sqrt{f_C . E_C}$by AISC coed, but from the experimental test results the strength values of the shear connectors in lightweignt concrete slabs shows about 70% on those of the shear connectors in normal concrete slabs by AISC code. Therefore, as a strength formula this paper suggests to multiply the established strength formula by reduction factor$(\varphi=0.7)$.