• 대한수학회지
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• 제34권2호
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• pp.345-370
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• 1997

In this paper, we introduce the Fock representation $U^{F, M}$ of the Heisenberg group $H_R^(g, h)$ associated with a positive definite symmetric half-integral matrix $M$ of degree h and prove that $U^{F, M}$ is unitarily equivalent to the Schrodinger representation of index $M$.

• 정보보호학회논문지
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• 제31권6호
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• pp.1149-1156
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• 2021

Brute force 공격을 가속화 시키는 Grover 알고리즘은 대칭키 암호의 키 복구에 적용 가능하며, NIST에서는 대칭키 암호에 대한 Grover 공격 비용을 양자 후 보안 강도 추정에 활용하고 있다. 본 논문에서는 DES를 양자 회로로 최적화 구현하여 Grover 알고리즘 공격 비용을 추정한다. NIST에서는 128, 192, 256-bit 키를 사용하는 대칭키 암호에 대해 AES의 공격 비용을 기준으로 양자 후 보안 강도를 추정하고 있다. DES에 대해 추정한 공격 비용은 DES가 양자 컴퓨터의 공격으로부터 어느 정도의 내성을 가지고 있는지 분석해볼 수 있다. 현재 64-bit 키를 사용하는 대칭키 암호들에 대한 양자 후 보안 지표가 아직 존재하지 않기 때문에 본 논문에서 추정한 64-bit 키를 사용하는 DES에 대한 Grover 공격 비용이 기준으로 활용될 수 있다. 제안하는 DES의 양자 회로 구현 적합성 및 공격 비용 분석에는 양자 프로그래밍 툴인 ProjectQ가 사용되었다.

• 대한기계학회논문집A
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• 제26권2호
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• pp.217-224
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• 2002

It is very important to measure and visualize the changes in the physical properties of fluid flow because this is the foundation of measurement techniques used in aerodynamics, heat transfer, plasma diagnostics, and stress analysis of transparent models. The optical methods are advantageous over probe-based techniques in the optical methods are of high speed, non-contact and are capable of providing full-field results with high spatial resolution. Therefore we propose the electronic speckle pattern interferometry(ESPI) that gives us a solution to overcome those limitations. In this paper the experimental results show qualitative and quantitative visualization of changes in the physical properties of the candle and alcohol lamp with 3D plotting. And we obtained the refractive index, mass density and temperature distribution of fluids. The results clearly show the process of flow phenomena and give the feasibility of quantitative interpretation of gasdynamics.

• Structural Engineering and Mechanics
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• 제48권3호
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• pp.291-308
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• 2013

Structural health monitoring is crucial to maintain the structural performance safely. Moreover, the Kullback-Leibler divergence (KLD) is applied usually to asset the similarity between different probability density functions in the pattern recognition. In this study, the KLD is employed to detect the damage. However the asymmetry of the KLD is a shortcoming for the damage detection, to overcoming this shortcoming, two other divergences and one statistic distribution are proposed. Then the damage identification by the KLD and its three descriptions from the symmetric point of view is investigated. In order to improve the reliability and accuracy of the four divergences, the gapped smoothing method (GSM) is adopted. On the basis of the damage index approach, the new damage index (DI) for detect damage more accurately based on the four divergences is developed. In the last, the grey relational coefficient and hypothesis test (GRCHT) is utilized to obtain the more precise damage identification results. Finally, a clear remarkable improvement can be observed. To demonstrate the feasibility and accuracy of the proposed method, examples of an isotropic beam with different damage scenarios are employed so as to check the present approaches numerically. The final results show that the developed approach successfully located the damaged region in all cases effect and accurately.

• 한국운동역학회지
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• 제23권2호
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• pp.169-177
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• 2013

The purpose of this study is to investigate the effect of aging and dual tasking to the postural control during quiet standing. It was hypothesized that the center of pressure (COP) dynamics would be differently affected by aging and characteristics of the task. Total 60 adults (35 young adults and 25 older adults) participated in this study. They conducted two different standing tasks (dual vs. Nondual) twice in a random order. Variability, complexity, coupling and symmetric index from the left, right and overall COPs were measured by various parameters in nonlinear, linear and frequency analyses methods. Results demonstrated that older adults had worse performance in postural control with decreased complexity in overall sway movement, and increased coupling between left and right limb COP movement, even though there was no significant difference in symmetric index. These tendencies are generally clearer in nonlinear measures at the dual task condition. Results implied that older adults had compensatory strategy in dual tasking which results in simple and combined postural movement patterns.

• 한국산업융합학회 논문집
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• 제22권3호
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• pp.273-280
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• 2019

Carbon fiber composite laminate has been widely used in the area of sports applications such as race car, golf club, fishing rods, yacht. In this study, carbon fiber composite laminate was used in the rear upright of leisure purposed small size single-seat electric race car to reduce its unsprung mass of suspension system. The focus of this research is to investigate in finding optimal stacking lay-up of rear upright laminated with carbon fiber composite in the early design phase. Forces transferred from circuit road to rear upright were estimated through MBD(Multi-Body Dynamics)model of the rear suspension geometry. To evaluate the strength of the rear upright laminated with carbon fiber composite which generally behaves in an anisotropic or orthotropic manner, FEA(Finite Element Analysis) model suitable for composite materials was built followed by its strength was evaluated depending on different stacking lay-up. The result showed that Symmetric stacking lay-up [$45^{\circ}/-45^{\circ}/90^{\circ}/0^{\circ}$]s for frontal area and symmetric stacking lay-up with 1mm aluminum core [$45^{\circ}/-45^{\circ}/90^{\circ}/Core$]s for rear area were most suitable of 16 lay-up cases from the side of both strength based on Tasi-wu failure index and weight.

• Journal of the Optical Society of Korea
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• 제7권3호
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• pp.156-159
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• 2003

Permanent structure of photoinduced singlemode waveguide in optical fluoride glasses was demonstrated using the self-channeled plasma filament excited by a femtosecond (110 fs) Ti:sapphire laser ($λ_p$ = 800 nm). The photoinduced refractive index modification in ZBLAN glasses reached a length of approximately 10 - 15 mm from the input surface of the optical glass with the diameters ranging from 5 to 8 ${\mu}{\textrm}{m}$ at input intensities more than l.0 ${\times}$ $10^{12}$ W/$\textrm{cm}^2$. The graded refractive index profiles were fabricated to be a symmetric form from the center of an optical fluoride glass and a maximum value of refractive index change (ㅿn) was measured to be l.3${\times}$$10^{-2}$. The beam profile of the output beam transmitted through the modified region showed that the photoinduced refractive index modification produced a permanent structure of singlemode waveguide.

• 한국레이저가공학회지
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• 제15권1호
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• pp.15-19
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• 2012

The fabrication of internal diffraction gratings with photoinduced refractive index modification in transparent materials was demonstrated using low-density plasma formation excited by a femtosecond (130 fs) Ti: sapphire laser (${\lambda}_p$=800 nm). The refractive index modifications with diameters ranging from $1{\mu}m$ to $3{\mu}m$ were photoinduced after plasma formation occurred upon irradiation with peak intensities of more than $2.0{\times}10^{13}W/cm^2$. The graded refractive index profile was fabricated to be a symmetric around from the center of the point at which low-density plasma occurred.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.767-772
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• 2006

The SWTR(Surface Water Treatment Rule) requires achieving removal 99.9% Giardia and 99.99% Virus. To remove Giardia and Virus, disinfection process is essential process. CT is important index for Disinfection performance. CT value is expressed by CXT. C is represented by disinfection concentration and T is represented by $T_{10}$ which means 90% contact time in clearwell. To improve Disinfection performance, it is desirable to increase $T_{10}$. Primary factor affected $T_{10}$ is flow Pattern. Because guide wall change that flow pattern is uniform, we have installed guide wall to increase $T_{10}$. In this paper, we have performed numerical analysis for clearwell installed symmetric guide wall and center divided guide wall using CFD. We have analyzed flow pattern and $T_{10}$ in each clearwell. And. we compare symmetric guide wall with center divided guide wall in flow pattern and $T_{10}$.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2023년도 학술발표회
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• pp.326-326
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• 2023

본 연구에서는 유역 내 다른 년도 관측 유량 데이터를 이용한 매개변수 최적화를 수행한 후, 최적화된 매개변수에 따라 다르게 추정된 유량 데이터를 이용해 발생하는 수문학적 가뭄 불확실성 분석을 수행하였다. 수문 모형은 장기 강우-유출분석에 주로 사용되는 Soil Water Assessment Tool (SWAT) 모형을 이용하였으며, Symmetric uncertainty을 이용해 불확실성 분석을 수행하였다. 모형 매개변수 최적화는 SWAT-CUP을 이용해 영산강 유역의 과거 1999년부터 2022년까지의관측 유량 데이터로 수행하였다. 최적화된 매개변수에 따라 추정되는 연평균 유량은 최대 5.59%의 차이를 발생시켰으며, 계절 유량은 봄 (6.1%), 여름 (14.6%), 가을 (9.7%), 겨울 (46.1%)의 차이를 발생시켰다. 그 후, 수문학적 가뭄지수인 Streamflow Drought Index (SDI)을 이용해 일 단위가뭄과 월 단위 가뭄 분석을 수행하였다. 매개변수에 따른 일 단위 가뭄 분석은 연평균 가뭄 발생일수가 최대 25.2일까지 차이가 발생하였으며, 월 단위 가뭄 역시 최적화된 매개변수에 가뭄 심도와 발생이 다르게 분석되었다. 그 후, Symmetric uncertainty을 이용한 불확실성 분석은 최적화된 매개변수에 따라 다르게 산정된 가뭄지수의 불확실성을 확인할 수 있었다. 본 연구는 수문학적 가뭄 분석 시, 다양한 관측 유량 데이터를 이용한 매개변수 최적화를 수행한 후, 이를 이용한 유량추정의 필요성을 확인할 수 있었다.