• ETRI Journal
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• 제25권5호
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• pp.315-320
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• 2003

Elliptic curve cryptography (ECC) offers the highest security per bit among the known public key cryptosystems. The operation of ECC is based on the arithmetic of the finite field. This paper presents the design of a 193-bit finite field multiplier and an inversion unit based on a normal basis representation in which the inversion and the square operation units are easy to implement. This scalable multiplier can be constructed in a variable structure depending on the performance area trade-off. We implement it using Verilog HDL and a 0.35 ${\mu}m$ CMOS cell library and verify the operation by simulation.

• 대한전자공학회논문지SD
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• 제40권12호
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• pp.80-86
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• 2003

타원곡선 암호(Elliptic Curve Crypto-graphy : ECC)는 기존의 어떤 공개키 암호 시스템보다 우수한 비트 당 안전도를 제공하고 있어 최근 큰 관심을 끌고 있다. 타원곡선 암호 시스템은 보다 작은 키 길이를 갖고 있어 시스템의 구현에 있어서 작은 메모리 공간과 적은 처리 전력을 필요로 하므로 다른 암호화 방식에 비해 임베디드 어플리케이션에 적용하는데 유리하다 본 논문에서는 제곱 연산이 용이한 정규기저로 표현된 유한체에서의 곱셈기를 구현하였다. 이 곱셈기는 타원곡선 암호에서 사용되는 GF(2/sup 193/) 상에서 구현하였고, Massey와 Omura가 제시한 병렬 입력-직렬 출력 곱셈기의 구조를 변형하여 출력의 크기와 설계면적을 조절할 수 있다. 또한 제안한 곱셈기를 적용하여 정규기저 역원기를 구현하였다. 곱셈기와 역원기는 HDL을 이용하여 설계하구 0.35㎛ CMOS 셀 라이브러리를 이용하여 구현하였으며 시뮬레이션을 통해 동작과 성능을 검증하였다.

• Current Optics and Photonics
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• 제6권3호
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• pp.270-281
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• 2022

Based on the transfer-matrix method (TMM), we report the characteristics of the interface states in one-dimensional (1D) composite structures consisting of two photonic crystals (PCs) composed of binary dielectrics A and B, with unit-cell configurations ABA (PC I) and BAB (PC II). The dependence of the interface states on the number of unit cells N and the boundary factor x are displayed. It is verified that the interface states are independent of N when the PC has inversion symmetry (x = 0.5). Besides, the composite structures support the formation of interface states independent of the PC symmetry, except that the positions of the interface states will be varied within the photonic band gaps. Moreover, the robustness of the interface states against nonuniformities is investigated by adding Gaussian noise to the layer thickness. In the case of inversion symmetry (x = 0.5) the most robust interface states are achieved, while for the other cases (x ≠ 0.5) interface states decay linearly with position inside the band gap. This work could shed light on the development of robust photonic devices.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.231-236
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• 2000

In order to predict depth of the pile forward modeling and inversion of magnetic logging data was conducted by using a finite line of dipoles model. The horizontal component as well as the vertical component of magnetic fields can be measured in the borehole, and the magnetic anomalies can be obtained by subtracting the Earth's magnetic field from the measurement. The magnetic anomalies of the pile are considered as vector sum of induced magnetization due to the Earth's magnetic field and remnant magnetization possessed by steel strings in the pile. The magnetic anomalies are used as input data for inversion from which the length, the magnetic moment per unit length, and the dip angle of the pile can be obtained. From the inversion of synthetic noisy data, and the data obtained from the field model test it is found that the driving depth of the pile can be determined as close to the order of measuring interval (5∼10㎝). It is also found that the resultant magnetic anomalies due to an individual steel string in the pile are almost same as those due to a group of steel strings located at the center of the pile. The magnetic logging method also can be used for locating reinforced bars, pipes, and steel casings.

• Journal of Biosystems Engineering
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• 제41권4호
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• pp.337-341
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• 2016

Purpose: Evaluation of atmospheric conditions for proper timing of spray application is important to prevent off-target movement of crop protection materials. Susceptible crops can be damaged downwind if proper application procedure is not followed. In our previous study, hourly data indicated unfavorable conditions, primarily between evening 18:00 hrs in the evening and 6:00 hrs next morning, during clear conditions in the hot summer months in the Mississippi delta. With the requirement of timely farm operations, sub-hourly data are required to provide better guidelines for pilots, as conditions of atmospheric stability can change rapidly. Although hourly data can be interpolated to some degree, finer resolution for data acquisition of the order of 15 min would provide pilots with more accurate recommendations to match the data recording frequency of local weather stations. Methods: In the present study, temperature and wind speed data obtained at a meteorological tower were re-sampled to calculate the atmospheric stability ratio for sub-hour and hourly recommendations. High-precision evaluation of temperature inversion periods influencing atmospheric stability was made considering strength, time of occurrence, and duration of temperature inversion. Results and Discussion: The results indicated that atmospheric stability could be determined at different time intervals providing consistent recommendations to aerial applicators, thereby avoiding temperature inversion with minimal off-target drift of the sprayed liquid.

• 한국실내디자인학회논문집
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• 제38호
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• pp.75-82
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• 2003

The symmetry is general geometric design principal in contemporary architecture shape. But, Symmetry sometimes easily causes unreasonable design. In some reason, two of symmetric units in the apartment, one side of unit have very reasonable plan and arrangement but opposite side unit nay not. For example, if the kitchen on right unit had right-handed arrangement, the symmetrical other would have left-handed kitchen arrangement. In addition to this, if each house unit has the same plan but different direction, each unit has different usage or affects the residents' life pattern. Nevertheless, Architects use only one unit plan to design public housing development by using symmetric operator (mirror, proper rotation, inversion center) at their option. This study suggests that using group theory and mathematical matrix rather than designer's discretion can solve this symmetry problem clearly. And, this study analysis the merits and demerits between each symmetrical pair of unit plan shapes by using mathematical point group theory and matrix.

• 대한수학회논문집
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• 제38권2호
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• pp.355-364
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• 2023

In this paper, we investigate the sums of the elements in the finite set $\{x^k:1{\leq}x{\leq}{\frac{n}{m}},\;gcd_u(x,n)=1\}$, where k, m and n are positive integers and gcd_u(x, n) is the unitary greatest common divisor of x and n. Moreover, for some cases of k and m, we can give the explicit formulae for the sums involving some well-known arithmetic functions.

• 지구물리
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• 제2권2호
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• pp.135-142
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• 1999

선형 자기쌍극자 모델의 하나인 철근에 대하여 3성분 자력계를 이용한 자력검층을 실시한 후 검층자료를 최소 자승법에 의한 역산을 이용하여 해석하였다. 본 실험에 사용된 철근의 길이는 1.12 m, 샘플링 간격은 0.05 m, 자력계와 철근사이의 거리는 0.3 m이며, 철근의 상단부를 깊이 0 m 지점에 고정하였다. 철근은 연직에 가깝도록 위치시켰다. FFT를 이용하여 평활화한 자기이상을 역산의 입력자료로 활용하였다. 검층자료의 해석을 위하여 선형 자기쌍극자의 상단부 심도, 길이, 단위 길이 당 자기모멘트, 자화방향(편각 및 복각), 경사방향과 경사각 등을 미지수로 설정하였다. 자기이상의 수평성분 및 수직성분 각각에 대한 역산 결과와 수평성분과 수직성분을 동시에 고려한 역산 결과를 비교하였는데 각각의 역산결과는 다소 차이를 보인다. 자기이상의 수평성분과 수직성분을 동시에 고려하여 역산을 수행하는 것이 각각의 성분을 역산하는 경우보다 정확한 해석이 가능한 것으로 판단된다. 이 때 철근 하단부의 추정 심도는 1.18 m로, 실제 심도인 1.12 m에 매우 근접하며, 철근의 복각은 -76°로 추정되었다. 철근의 복각이 음(-)의 값을 갖는 것은 철근의 유도자화 강도에 비하여 잔류자화 강도가 훨씬 커서, 전체적인 자화 방향이 철근의 상단 방향을 향하고 있기 때문으로 해석된다.

• 대한전자공학회논문지SD
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• 제45권11호
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• pp.1-7
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• 2008

본 연구에서는 양자 현상을 고려한 나노미터 MuGFET의 C-V 특성을 분석하기 위하여 2차원 Poisson-$Schr{\ddot{o}}dinger$ 방정식을 self-consisnt하게 풀 수 있는 시뮬레이터를 구현하였다. 소자 시뮬레이터를 이용하여 양자 현상으로 인한 소자크기와 게이트 구조에 따른 게이트-채널 커패시턴스 특성을 분석하였다. 소자의 크기가 감소할수록 단위 면적당 게이트-채널 커패시턴스는 증가하였다. 그리고 게이트 구조가 다른 소자에서는 게이트-채널 커패시턴스가 유효게이트 수가 증가할수록 감소하였다. 이런 결과를 실리콘 표면의 전자농도 분포와 인버전 커패시턴스로 설명하였다 또한 인버전 커패시턴스로부터 소자의 크기 및 게이트 구조에 따른 inversion-layer centroid 길이도 계산하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.650-653
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• 2002

The increaseing speeds are accompanied by decreases in pulse rise and fall time in VLSI circuits. These accenturate the high frequency spectral contents of the signals and cause the frequency dependent loss of the conductors which interconnect the various sub-circuits composing of VLSI circuit. The lossy effect is approximated by the square root of frequency dependence of the per unit length resistance. In the practical applications, several problems may arise along with this approximation, so we extend our investigation of the lossy effect by numerical Laplace inversion method.