• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.1
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• pp.15-23
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• 2003

This paper proposes a fast direction of arrival (DOA) estimation algorithm that can rapidly estimate incidence angles of incoming signals using a pseudo covariance matrix. The conventional subspace DOA estimation methods such as MUSIC (multiple signal classification) algorithms need many sample signals to acquire covariance matrix of input signals. Thus, it is difficult to estimate the DOAs of signals because they cannot perform DOA estimation during receiving sample signals. Also if the D0As of signals are changing rapidly, conventional algorithms cannot estimate incidence angles of signals exactly. The proposed algorithm obtains bearing response and directional spectrum after acquiring pseudo covariance matrix of each snapshot. The incidence angles can be exactly estimated by using the bearing response and directional spectrum. The proposed DOA estimation algorithm uses only concurrent snapshot so as to obtain covariance matrix. Compared to conventional DOA estimation methods. The proposed algorithm has an advantage that can estimate DOA of signal rapidly.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.1
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• pp.41-46
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• 2010

In this paper, the DoA(Direction of Arrival) estimator using unitary MUSIC algorithm is studied. The complex-valued correlation matrix of MUSIC algorithm is transformed to the real-valued one using unitary transform for easy implementation. The eigenvalue and eigenvector are obtained by the combined Jacobi-CORDIC algorithm. CORDIC algorithm can be implemented by only ADD and SHIFT operations and MUSIC spectrum computed by 256 point DFT algorithm. Results of unitary MUSIC algorithm designed by System Generator for FPGA implementation is entirely consistent with Matlab results. Its performance is evaluated through hardware co-simulation and resource estimation.

• The Journal of the Acoustical Society of Korea
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• v.41 no.4
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• pp.397-409
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• 2022

A model is developed for the calculation of sea surface generated ambient noise in the range dependent ocean environment. The sources are located in the horizontal plane all around and their depths are at the near-surface. The receiver array is located in the range dependent ocean waveguide. One-way coupled mode method is used to model the acoustic propagation between the sources and receiver in the range dependent waveguide, and the cross spectral density matrix of noise is derived. In simulation, noise intensity, beamforming result and coherence function are calculated from the cross spectral density matrix. These results are compared with those in the range independent environment. The modeling result shows the effect of the vertical directionality and asymmetry characteristics of the horizontal plane.

• Transactions of the Korean Society of Mechanical Engineers
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• v.5 no.3
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• pp.178-182
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• 1981

쉘이 복합재로 제작되었거나 보강재를 사용하였을때에는 쉘요소의 역학적 특성은 방향성을 가지게 된다. 이 논문에서는 선형관계식을 사용하여 동적 표면가동을 받는 이방성원통쉘의 안정성을 고려하여 다루었다. 재료의 이방성을 고려하여 3방향 즉, 축방향, 둘레방향 및 반경향의 실성항이 포함된 운동방장실을 유도하였다. 동적 안전성의 해석은 Bolotin 의 방법을 따랐으며 근사해를 행렬식행으로 제시하였다. 수직열로 외압을 받는 원통쉘의 좌단을 다루었으며 본 이론과 고전이론 사이의 차이점을 검토하였다.

• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.25-30
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• 1994

We derive a set of formuale which show one-to-one correspondence between the the unitary Jones matrices of transparent anisotropic media and the rotational transformations on the Poincare sphere. By using the formuale one can determine the vectorial representation of the rotational transformation on the Poincare sphere which specifies the direction of the axis and the angle of the rotation in terms of the three parameters specific to the corresponding unitary Jones matrix, and conversely the the three parameters of the uniatry Jones matrix in terms of the vectorial representation of the corresponding rotational transformation on the Poincare sphere. To understand the polarization transmission characteristics of an optical system consisting of transparent linear anisotropic media, start with the Jones calculus to get the unitary Jones matrix for the whole system and then convert it to a rotational transformation on the Poincare sphere, from which we can intuitively understand the effect of the optical system on the polarization state of the light passing through the system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1990.10a
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• pp.199-203
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• 1990

본 연구에서는 일반적인 형상을 갖는 회전축에서 축 방향 하중과 토오크를 각각 또는 동시에 고려할 수 있는 전달 행렬을 수식화하였고, 이에 의한 진 동 특성을 해석하기 위하여 강제진동 해석 및 자유진동 해석을 수행하였으 며, 해석결과에 대한 신빙성을 얻기 위하여 과도진동 해석 및 이산화 FFT를 통하여 검산기능을 추가하였다. 그리고 전달 행렬법에 새로운 고유치 수치해 법과 수치 적분법의 적용을 통하여 `수렴성과 안정성을 개선하였다.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.3175-3177
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• 2000

전압원과 전류원 및 RLC 수동소자들로 구성된 대형회로망에서 망(網)과 마디를 복합시킨 새로운 회로망 해석법을 제시하였다. 종래의 수식적 유도 과정이 불필요하며 도식적 추출에 의해 대형회로망을 간단히 해석한다 각 전원은 직렬 또는 병렬 임피던스를 반드시 수반하고 있지 않아도 무방하다. 망 설정과 마디 선정 과정에서의 전원 처리에 의해 회로망의 도형화 시켰고, 그로부터 행렬 형태의 부분 식을 도출하였다. 망해석법에 의한 방식과 마디해석법에 의한 기법이 가지전류방향 행렬에 의해 합성된다. 합성된 최종 식은 컴퓨터 몫이다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.3
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• pp.459-464
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• 2001

We propose a transmit beamforming algerian for array antenna in FDD (Frequency Division Duplex) environments. The proposed method estimates the directions and spectra of the users, and constructs the spatial covariance matrix of the interferences at the downlink frequency. The weights are computed by that covariance matrix and desired user's direction vector Simulations are performed under Rayleigh fading environments. The proposed method don't need the data feedback, has the enhanced performance in BER (Bit Error Rate).

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.5
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• pp.1426-1432
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• 1991

본 연구에서는 Timoshenko보이론과 전달행렬법에 의해서 얻어지는 베어링의 반력들과 주축계의 불완전진동모드간의 선형관계를 이용하여 원리적으로 반복계산없이 반경방향과 굽힘모멘트방향의 선형등방성 베어링계수들을 규명하는 방법을 제안하였다. 제안된 규명방법은 주축계에 사용된 베어링의 수보다 진동모드에 대한 측정점의 수가 2배 이상 많아야 한다는 조건을 가지고 있다. 또한 선형 연립방정식으로 부터 직접 규명된 베어링계수들의 일부가 정보의 부정확성에 의해서 물리적으로 타당성이 없는 음수로 나타나는 경우에는 측정결과와의 차이를 최소화시키면서, 물리적으로 타당성이 있는 양수의 베어링계수들을 규명할 수 있는 방법이 제안조건들을 가진 최적화문제의 형태로 제시되었다. 그리고 제시된 최적화문제의 해는 선형화방법(linearization method)를 통해서 얻었다. 아울러서 주축계의 실험모델에 대한 가진실험결과를 이용 하여 제안된 규명방법의 유용성을 평가하였다.

• The Mathematical Education
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• v.62 no.2
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• pp.269-287
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• 2023

Matrix theory is widely used not only in mathematics, natural sciences, and engineering, but also in social sciences and artificial intelligence. In the 2009 revised mathematics curriculum, matrices were removed from high school math education to reduce the burden on students, but in anticipation of the age of artificial intelligence, they will be reintegrated into the 2022 revised education curriculum. Therefore, there is a need to analyze the matrix content covered in other countries to suggest a meaningful direction for matrix education and to derive implications for textbook composition. In this study, we analyzed the German mathematics curriculum and standard education curriculum, as well as the matrix units in the German Hesse state mathematics curriculum and textbook, and identified the characteristics of their content elements and development methods. As a result of our analysis, it was found that the German textbooks cover matrices in three categories: matrices for solving linear equations, matrices for explaining linear transformations, and matrices for explaining transition processes. It was also found that the emphasis was on mathematical reasoning and modeling when learning matrices. Based on these findings, we suggest that if matrices are to be reintegrated into school mathematics, the curriculum should focus on deep conceptual understanding, mathematical reasoning, and mathematical modeling in textbook composition.