• 대한수학회지
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• 제44권3호
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• pp.627-645
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• 2007

We investigate the eigenvalues of the semi-circulant preconditioned matrix for the finite difference scheme corresponding to the second-order elliptic operator with the variable coefficients given by $L_vu\;:=-{\Delta}u+a(x,\;y)u_x+b(x,\;y)u_y+d(x,\;y)u$, where a and b are continuously differentiable functions and d is a positive bounded function. The semi-circulant preconditioning operator $L_cu$ is constructed by using the leading term of $L_vu$ plus the constant reaction term such that $L_cu\;:=-{\Delta}u+d_cu$. Using the field of values arguments, we show that the eigenvalues of the preconditioned matrix are clustered at some number. Some numerical evidences are also provided.

• 한국시뮬레이션학회논문지
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• 제13권2호
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• pp.1-12
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• 2004

This paper estimated the arrival angle and electric wave delay time using the space method law and the directions of arrival (DOA) estimation algorithm in case of signal correlation. Space method law is the method used to repress cross correlation before applying the weight value to the receiving signal. The values of the diagonal elements in the correlation matrix were averaged to replace as the diagonal elements value. In the area of wireless communication or mobile communication, there are high correlations in case of low delay time difference in multiple waves. This causes the quality of the communication to drop due to interference with the desired signal elements. This paper estimated the arrival angle and electric wave delay time using the space method law and the MUSIC algorithm. With the arrival angle algorithm, the arrival angle cannot be estimated below 5 in case of signal correlations because the angle resolution capacity decreases accordingly. The super resolution capacity was estimated to determine the arrival angle below 5 in this paper. In addition, the proposed algorithm estimated the short delay time difference to be below 20ns.

• 한국정보과학회논문지:시스템및이론
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• 제32권11_12호
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• pp.692-704
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• 2005

컴퓨터 하드웨어의 급속한 발전으로 그래픽 프로세서 유닛(Graphics Processor Units : GPUs)은 굉장한 메모리 대역폭과 산술 능역을 보유하게 되어 범용 계산에 많이 활용되고 있으며, 특히 계산 집약적인 물리 기반 시뮬레이션(physics based simulation)의 GPU 구현이 활발하게 연구되고 있다. 물리 기반 시뮬레이션의 기본이 되는 미분방정식 풀이 과정에서 삼중대각행렬(tridiagonal matrix) 시스템은 유한차분(finite-difference) 근사에 의해서 자주 나타나는 선형시스템으로 물리 기반 시뮬레이션 관점에서 삼중대각행렬 시스템의 빠른 풀이는 중요한 연구 분야이다. 본 논문에서는 GPU에서 삼중대각행렬 시스템 풀이를 빠르게 구현할 수 있는 방법을 제안한다. 벡터 프로세서(vector processor) 계산에서 삼중대각행렬 시스템 풀이 방법으로 널리 사용되는 cyclic reduction 또는 odd-even reduction 알고리즘을 GPU에서 구현하였다. 본 논문에서 제안한 방법을 삼중대각행렬 시스템 풀이 방법으로 잘 알려져 있는 Thomas 방법과 GPU를 이용한 선형시스템 풀이에서 좋은 성과를 보이고 있는 conjugate gradient 방법과 비교할 때 상당한 성능 향상을 얻을 수 있었다. 또한, 열전도(heat conduction) 방정식, 이류 확산(advection-diffusion) 방정식, 얕은 물(shallow water) 방정식에 의한 물리 기반 시뮬레이션의 GPU 구현에 본 논문에서 제안한 방법을 사용하여 1024x1024 격자의 계산 영역에서 초당 35프레임 이상의 놀라운 성능을 보여주었다.

• 한국자기공명학회:학술대회논문집
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• 한국자기공명학회 2002년도 International Symposium on Magnetic Resonance
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• pp.35-35
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• 2002

• 대한토목학회논문집
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• 제8권4호
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• pp.33-39
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• 1988

본(本) 연구(硏究)는 matrix 해석(解析)(rigorous-method)을 이용(利用)하여 정밀(情密) traverse망(網)을 조정(調整)하는데 목적이 있다. 본(本) 연구(硏究) 결과(結果), matrix 해석(解析)에 의(依)한 엄밀해법(嚴密解法)으로도 복잡(複雜)한 traverse망(網)을 신속(迅速) 정확(正確)하게 처리(處理)할 수 있다. 또한 종래(從來)의 근사해법(approximate-method)을 본(本) matrix 해법(解法)의 조정(調整)값과 비교(比較)한 결과(結果) 평균(平均)제곱오차범위이내(誤差範圍以內)에 있고, 조정좌표(調整座標)값의 비교차(比較差)도 0.4~0.9mm정도(程度)로 나타났으며, 이로써 근사해법(approximate-method)의 실용적(實用的) 가치(價値)를 입증(立證)하게 되었다.

• Journal of Biosystems Engineering
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• 제30권4호
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• pp.195-201
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• 2005

The output of Stirling engine is influenced by the regenerator effectiveness. The regenerator effectiveness is influenced by heat transfer and flow friction loss of the regenerator matrix. In this paper, in order to provide a basic data for the design of regenerator matrix, characteristics of heat transfer and flow friction loss were investigated by a packed method of matrix in the oscillating flow as the same condition of operation in a Stirling engine. As matrices, several kinds of combined wire screen meshes were used. The results are summarized as follows; The packed meshes with high mesh no. in the side of heater part of regenerator showed effective than the packed meshes with low mesh no. in the side of cooler part of regenerator. The temperature difference and pressure drop of the regenerator were not made by the specific surface area of wire screen meshes but by the minimum free-flow area to the total frontal area. Among the No. 150 single screen meshes, 200-60 combined meshes, the 200-150-100 combined meshes showed the highest in effectiveness.

• 한국컴퓨터정보학회논문지
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• 제20권12호
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• pp.67-74
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• 2015

The heat conduction equation, a type of a Poisson equation which can be applied in various areas of engineering is calculating its value with the iteration method in general. The equation which had difference discretization of the heat conduction equation is the simultaneous equation, and each line has the characteristic of expressing in sparse matrix of the equivalent number of none-zero elements with neighboring grids. In this paper, we propose a data structure for sparse matrix that can calculate the value faster with less memory use calculate the heat conduction equation. To verify whether the proposed data structure efficiently calculates the value compared to the other sparse matrix representations, we apply the representative iteration method, CG (Conjugate Gradient), and presents experiment results of time consumed to get values, calculation time of each step and relevant time consumption ratio, and memory usage amount. The results of this experiment could be used to estimate main elements of calculating the value of the general heat conduction equation, such as time consumed, the memory usage amount.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 추계 학술논문 발표대회
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• pp.196-197
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• 2013

This study is the experiment for manufacturing the Lightweight non-cement matrix based on the Blast furnace slag. And, the matrix was manufactured matrix by generating the bubble just by the reaction of KOH that is the alkali accelerator and paper ash, instead of the general foaming agent, that is the waste managed of incineration the pulp sludge generated in the process of manufacturing the paper. Consequently, the density according to the addition rate of KOH represented the tendency to increase. And it showed up that density of the matrix adding KOH 22.5% was the lowest. As to the strength test result, strength following addition rate of KOH increased. Since the bubble is generated in the reaction of KOH and paper ash, this shows the very low intensity but it is determined to be the result that the amount of vacant space is decreased because the bubble generated in the mixture process comes up as the specific gravity difference.

• Macromolecular Research
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• 제16권2호
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• pp.108-112
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• 2008

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis of nonpolar polymeric materials is affected by the sample preparation as well as the matrix and cationizing agent. This study examined the influence of silver salt types on the MALDI analysis of polybutadiene (PB). Silver trifluoroacetate (AgTFA), silver benzoate (AgBz), silver nitrate ($AgNO_3$), and silver p-toluenesulfonate (AgTS) were used as the silver salts to compare the MALDI mass spectra of PB. The mixture solution of PB and 2,5-dihydroxybenzoic acid (DHB), as a matrix dissolved in THF, was spotted on the sample plate and dried. A droplet of the aqueous silver salt solution was placed onto the mixture. The mass spectrum with AgBz showed the clear $[M+Ag]^+$ ion distribution of PB while the mass spectrum with AgTFA did not show $[M+Ag]^+$ ions but only silver cluster ions. The mass spectra with $AgNO_3$ and AgTS did not show a clear $[M+Ag]^+$ ion distribution. The difference in the formation of $[M+Ag]^+$ ions of PB depending on the silver salts was attributed to the silver cation transfer reaction between the silver salt and the matrix (DHB). The mass spectrum showed a clear $[M+Ag]^+$ ion distribution of PB when the conjugate acid of the silver salt was less acidic than the matrix.

• Structural Engineering and Mechanics
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• 제17권6호
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• pp.735-749
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• 2004

This work presents a direct integration scheme, based on a fourth order finite difference approach, for elastodynamics. The proposed scheme was chosen as an alternative for attenuating the errors due to the use of the central difference method, mainly when the time-step length approaches the critical time-step. In addition to eliminating the spurious numerical oscillations, the fourth order finite difference scheme keeps the advantages of the central difference method: reduced computer storage and no requirement of factorisation of the effective stiffness matrix in the step-by-step solution. A study concerning the stability of the fourth order finite difference scheme is presented. The Finite Element Method and the Boundary Element Method are employed to solve elastodynamic problems. In order to verify the accuracy of the proposed scheme, two examples are presented and discussed at the end of this work.