• 방송공학회논문지
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• 제15권5호
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• pp.672-680
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• 2010

본 논문은 H.264 동영상 부호화를 위한 적응적인 양자화 행렬 선택방법을 제안한다. 기존의 H.264 양자화 방법은 각 프레임에 동일한 양자화 행렬을 적용하기 때문에 영상의 지역적 특성을 고려하지 못해 코딩 효율이 저하될 수 있다. 이러한 문제점을 개선하고자 프레임 전체에 동일한 양자화 행렬을 적용하는 대신 매크로블록 단위로 블록이 가지는 방향성을 이용해 적응적으로 양자화 행렬을 적용하는 방법을 제안한다. 먼저, 각 블록의 방향성을 공간적으로 인접 블록의 인트라 예측모드 특성을 이용하여 결정한다. 방향성이 존재하는 블록에 대해서는 제안한 방식의 가중치 양자화 행렬을 적용하고, 방향성이 존재하지 않는 블록에 대해서는 기존의 양자화 행렬을 적용한다. 가중치 양자화 행렬은 인트라 예측모드에 따라 블록의 변환 계수의 통계적인 분포를 기반으로 설계되었기 때문에, 예측모드의 특성에 적합하게 양자화된다. 실험 결과를 통해 제안한 알고리즘이 BD rate 측면에서 기존 방법 대비 약 2% 정도의 부호화 효율이 상승됨을 확인할 수 있다.

• 대한조선학회논문집
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• 제47권3호
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• pp.369-376
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• 2010

In this study, a radiation and a diffraction problems of a floating body in two-layer fluids were solved by the Numerical Wave Tank(NWT) technique in the frequency domain. In two-layer fluids, two different wave modes exist and the hydrodynamic coefficients can be obtained separately for each mode. The two-domain Boundary Element Method(BEM) in the potential fluid using the whole-domain matrix scheme was used to investigate the characteristics of wave forces, added mass and damping coefficients. The effects of the ratio of density and water depth in the lower domain were also evaluated and compared with given references.

• 대한수학회보
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• 제50권6호
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• pp.1887-1903
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• 2013

We continue the study of McCoy condition to analyze zero-dividing polynomials for the constant annihilators in the ideals generated by the coefficients. In the process we introduce the concept of ideal-${\pi}$-McCoy rings, extending known results related to McCoy condition. It is shown that the class of ideal-${\pi}$-McCoy rings contains both strongly McCoy rings whose non-regular polynomials are nilpotent and 2-primal rings. We also investigate relations between the ideal-${\pi}$-McCoy property and other standard ring theoretic properties. Moreover we extend the class of ideal-${\pi}$-McCoy rings by examining various sorts of ordinary ring extensions.

• Journal of electromagnetic engineering and science
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• 제15권4호
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• pp.258-265
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• 2015

A de-embedding method for multiport networks, especially for coupled odd interconnection lines, is presented in this paper. This method does not require a conversion from S-parameters to T-parameters, which is widely used in the de-embedding technique of multiport networks based on cascaded simple two-port relations, whereas here, we apply an operation to the S-matrix to generate all the uncoupled and coupled coefficients. The derivation of the method is based on the relations of incident and reflected waves between the input of the entire network and the input of the intrinsic device under test (DUT). The characteristics of the intrinsic DUT are eventually achieved and expressed as a function of the S-parameters of the whole network, which are easily obtained. The derived coefficients constitute ABCD-parameters for a convenient implementation of the method into cascaded multiport networks. A validation was performed based on a spice-like circuit simulator, and this verified the proposed method for both uncoupled and coupled cases.

• 대한화학회지
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• 제31권1호
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• pp.64-70
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• 1987

모자나이트광에서 희토류원소(Y 및 Th포함)를 분리하여 X-선 형광분광법으로 정량하였다. 희토류원소간의 상호간섭이 있으므로 이를 메트릭스 계수를 이용한 실험계수법으로 보정하였다. 이 방법에서 표준시료의 수는 메트릭스 계수에는 큰 영향을 미치지만 분석결과는 큰 차이가 없었으며 유도결합플라스마 분광법에 의한 분석결과와 비교적 잘 일치하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(1)
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• pp.211-214
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• 2002

In this paper, we present a simple method for characterizing a rectangular waveguide to circular waveguide transition Three standard loads consisting of a short circuit, an offset short circuit 1, and an offset short circuit 2 are sequentially connected to the circular waveguide port and the reflection coefficient at port 1 Is measured for each case. From known reflection coefficients, of standard loads and measured reflection coefficients, the scattering matrix of the transition Is obtained. The proposed method Is verified by the numerical experiment using a commercial software HFSS and by measurments of a actual rectangular-to-circular waveguide transition.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.143-150
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• 1999

Elastic wave propagation in a multilayered elastic half-plane is studied by using the Cagniard-de Hoop method. After the unknowns are expressed in terms of the reflection and transmission coefficients in the in terms of the reflection and transmission coefficients in the integral-transformed domains they are assmbled to form the global matrix equation. The inverse Laplace transform of each term is done by applying the Cagniard-de Hoop methods. As a numerical example a four-layered half-plane is considered where a point source is applied to the first layer. The method described in the present study can be used in checking other numerical methods such as FDM.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.838-840
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• 1996

Hopf and saddle-node bifurcation have been recognized as some of the reasons for voltage stability problems in a variety of power system models. Local bifurcations are detected by monitoring the eigenvalues of the current operating point. Therefore, many papers have used the methods using the eigenvalues. However, this paper discusses the bifurcations without calculating the eigenvalues as the system parameters vary In the 3 node system. Instead of calculating the eigenvalues, we use directly the coefficients of characteristic equation of Jacobian matrix. Also, the coefficients are used as stability index.

• 상하수도학회지
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• 제13권3호
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• pp.42-55
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• 1999

A mathematical model for biological nutrient removal in a sequencing batch reactor process, which is based on the IAWQ Activated Sludge Model No. 2 with a few modifications, has been developed. Twenty water quality components and twenty three kinetic equations are incorporated in the model. The model is structured in the matrix form based on the law of mass conservation using stoichiometry and kinetic equations. Stoichiometric coefficients and kinetic parameters included in the model equations are chosen from the literature. A multistep predictor-corrector algorithm of variable step-size is adopted for solving the vector nonlinear ordinary differential equations. The simulation for experimental results is conducted to evaluate the validity of the model and to calibrate coefficients and parameters. The simulation using the model well represents the experimental results from laboratory. The mathematical model developed in this study may be utilized for the design and operation of a sequencing batch reactor process under the steady and unsteady-state at various environmental conditions.

• Communications for Statistical Applications and Methods
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• 제28권3호
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• pp.295-305
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• 2021

Most graphical representation methods for two-dimensional contingency tables are based on the frequencies, probabilities, association measures, and goodness-of-fit statistics. In this work, a method is proposed to represent the correlation coefficients for each of the two selected levels of the row and column variables. Using the correlation coefficients, one can obtain the vector-matrix that represents the angle corresponding to each cell. Thus, these vectors are represented as a unit circle with angles. This is called a CC plot, which is a correlation plot for a contingency table. When the CC plot is used with other graphical methods as well as statistical models, more advanced analyses including the relationship among the cells of the row or column variables could be derived.