• 전자공학회논문지
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• 제50권8호
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• pp.94-102
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• 2013

선형 배열 안테나의 구조가 배열 안테나의 중심을 기준으로 대칭 구조인 점을 이용하여 효율적으로 배열 안테나의 빔 주사각에 따른 방사패턴을 계산할 수 있는 mirror AEP (active element pattern) 방법을 제안한다. Mirror AEP 방법은 AEP 방법과 비교하여 배열 안테나의 방사패턴을 계산하기 위하여 필요한 full-wave 전산모의를 이용하여 구하는 소자의 AEP 수를 약반으로 줄일 수 있기 때문에 계산 시간을 약 반으로 줄일 수 있다. 배열 안테나를 구성하는 단위 안테나 소자의 방사패턴이 대칭인 경우에는 mirror AEP 방법으로 계산한 방사패턴과 full-wave 전산모의를 이용하여 구한 방사패턴과의 차이가 넓은 빔 주사각 범위에서 매우 작았다.

• 대한수학회보
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• 제52권4호
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• pp.1113-1122
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• 2015

This paper is concerned with the pattern formation of a diffusive predator-prey model with two time delays. Based upon an analysis of Hopf bifurcation, we demonstrate that time delays can induce spatial patterns under some conditions. Moreover, by use of a series of numerical simulations, we show that the type of spatial patterns is the spiral wave. Finally, we demonstrate that the spiral wave is asymptotically stable.

• 전기의세계
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• 제14권1호
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• pp.26-34
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• 1965

The radiation patterns and impedance of the half wave solt on the wide side of rectangular wave guide are analyzed. The measuring methods and procedures are described. And that the experimental data of the pattern and impedance of the slot are presented which are consistent with the theoretical values. The causes of error are also considered and are believed to be tolerable for the pattern and input impedance measurements. The usefulness of the slot antenna tested are also described.

• 한국정보통신학회논문지
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• 제20권2호
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• pp.437-444
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• 2016

일반적인 부정맥 분류 방법의 경우 심방 박동 수와 관련한 PP간격, P모양의 다양성과 같은 조건을 이용하는데, 잡음으로 인해 정확한 P파의 검출이 어렵기 때문에 잡음의 영향을 비교적 적게 받는 R파를 이용하는 것이 유리하다. 따라서 본 연구에서는 R파 중심의 ECG(electrocardiography) 패턴 분석과 템플릿 문턱치를 도입하여 조기수축 부정맥 분류 방법을 제안한다. 이를 위해 형태 연산을 통한 전 처리 과정과 차감 동작 기법을 통해 R파를 검출하였다. 이후 RR 간격의 평균 가중치와 변화율을 이용하여 먼저 조기수축 파형의 패턴을 분류하고, R파의 진폭에 대한 템플릿 문턱값을 통해 조기심실수축과 조기심방수축을 분류하는 알고리즘을 개발하였다. 제안한 방법의 우수성을 입증하기 위해 조기 심방과 심실수축이 30개 이상 포함된 MIT-BIH 6개의 레코드를 대상으로 한 R파의 평균 검출율은 99.77%의 성능을 나타내었고, 조기심실수축과 심방수축 부정맥은 각각 94.91%와 95.76%의 평균 분류율을 나타내었다.

• 디지털산업정보학회논문지
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• 제13권4호
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• pp.91-98
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• 2017

Previous works for detecting arrhythmia have mostly used nonlinear method such as artificial neural network, fuzzy theory, support vector machine to increase classification accuracy. Most methods require higher computational cost and larger processing time. Therefore it is necessary to design efficient algorithm that classifies PVC(premature ventricular contraction) and decreases computational cost by accurately detecting minimal feature point based on only R peak through optimal R wave. We propose an optimal R wave detection and PVC classification method through extracting minimal feature point in IoT environment. For this purpose, we detected R wave through optimal threshold value and extracted RR interval and R peak pattern from noise-free ECG signal through the preprocessing method. Also, we classified PVC in realtime through RR interval and R peak pattern. The performance of R wave detection and PVC classification is evaluated by using record of MIT-BIH arrhythmia database. The achieved scores indicate the average of 99.758% in R wave detection and the rate of 93.94% in PVC classification.

• 수산해양기술연구
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• 제28권2호
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• pp.228-239
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• 1992

The purpose of the present research is to develop an efficient numerical method for the calculation of potential flow and predict the wave-making resistance for the application to ship design of tuna purse seiner. The paper deals with the numerical calculation of potential flow around the series 60 with forward velocity by the new slender ship theory. This new slender ship theory is based on the asymptotic expression of the Kelvin-source, distributed over the small matrix at each transverse section so as to satisfy the approximate hull boundary condition due to the assumption of slender body. Some numerical results for series 60, C sub(b) =0.6, hull are presented in this paper. The wave pattern and wave resistance are computed at two Froude numbers, 0.267 and 0.304. These results are better than those of Michell's thin ship theory in comparison with measured results. However, it costs much time to compute not only wave resistance but also wave pattern over some range of Froude numbers. More improvements are strongly desired in the numerical procedure.

• International Journal of Naval Architecture and Ocean Engineering
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• 제3권3호
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• pp.159-173
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• 2011

The two different numerical approaches for solving the nonlinear ship wave problem are discussed in the present paper. One is based on a panel method, which neglects the viscous effects. The other is based on a finite volume method, which take into account the viscous effects by solving RANS equations. Focus is laid upon on the advantages and disadvantages of two methods. The developed methods are applied to calculating the flow around Series 60 hull to validate the performance of the present nonlinear methods. Although the two methods employ quite different numerical approaches, the calculated wave patterns from both methods show good agreements with the experiments. However the potential method simu-lates the global wave pattern accurately, while the viscous method shows better performance for the local wave prediction near a ship.

• 한국광학회:학술대회논문집
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• 한국광학회 1990년도 제5회 파동 및 레이저 학술발표회 5th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.95-101
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• 1990

Parallel optical arithmetic techniques have been developed using the correlation property of optical phase conjugate wave generated by degenerated four wave-mixing. In this paper, conventional rectangular-type coded pattern used for optical logic system is replaced by circular one for effective beam coupling in a photorefractive $BaTiO_3$ material. By adequately adjusting the distance between circular-type pixels of the input pattern and grouping the correlated output, optical binary half addition/subtraction, binary multiplication and, matrix-matrix computation are demonstrated.

• 한국한의학연구원논문집
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• 제18권2호
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• pp.139-149
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• 2012

Objectives : This is the study to understand of the pulse wave factor according to BMI and period of sterility on female, and to confirm the relationship of pulse wave factor among left and right inch, bar and cubit. Methods : The Questions and measurement of the pulse wave were operated with subjects(76 sterile females using on public health center). The measurement of the pulse wave was operated in 6 part of left and right inch, bar and cubit. The pulse wave was prior measured in part of left bar (i.e. interior pulsation part of radial process styloides in left hand), and next was measured in part of left inch and bar. And the pulse wave was operated samely in part of right inch, bar and cubit. Results : The results were as follows. The pulse energy of 6 part of left and right inch, bar and cubit was showed statistical significance and decreased in order of left inch, right inch, left cubit, right cubit, left inch, right bar. The left and right inch and cubit were showed numerical value of normal range, but left and right bar were showed lower pulse eneregy than normal range. Also left and right cubit were showed lower than left and right inch, and higher than left and right bar. In BMI, The pulse energy of left and right inch, cubit and the average of right hand was not showed statistical significance in the range of low-weight, normal, over-weight and obesity. But in the left and right bar and the average of left hand, the pulse energy of over-weight and obesity group were showed significantly higher than low-weight group. And the pulse wave factor was divided the pattern of h1 showing high numerical value in inch (Ap, As, Aw) and the pattern of Wm showing high numerical value in bar and cubit (RAI, Ad) Conclusions : The low pulse energy of bar was significant observation on the setting of oriental medical diagnostic index on sterilitas. Also, in the numerical value pattern of diverse pulse wave factor, it was divided the pattern of high numerical value in inch and the pattern of high numerical value in bar and cubit. On this, we think that the studies need in the future.

• 한국정보통신학회논문지
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• 제18권4호
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• pp.825-832
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• 2014

조기심실수축 분류를 위한 기존 연구들은 분류의 정확성을 높이기 위해 신경망, 퍼지 이론, SVM 등과 같은 비선형 방법이 주로 사용되어 왔다. 이러한 대부분의 방법들은 P-QRS-T 지점의 정확한 측정을 필요로 하며, 데이터의 가공 및 연산이 복잡하다. 연산의 복잡도를 줄이기 위한 여러 가지 방법들이 제안되어 왔지만, 분류의 정확도가 떨어지는 문제점이 있었다. 또한 PVC는 개인의 특징에 따라 다양한 QRS 패턴이 존재하기 때문에 정확도에 한계가 있다. 따라서 이러한 문제점을 극복하기 위해서는 최소한의 특징점을 추출함으로써 연산의 복잡도를 줄이고, 개인마다 다른 QRS 패턴에 따라 PVC를 정확하게 분류할 수 있는 알고리즘이 필요하다. 따라서 본 연구에서는 QRS 패턴에 따른 QS 간격과 R파 진폭 변화율을 이용한 PVC 분류 방법을 제안한다. 이를 위해 전처리를 통해 잡음이 제거된 심전도 신호에서 R파, RR 간격, QRS 패턴을 추출한다. 이후 그 패턴에 따른 QS 간격과 R파의 진폭 변화율에 따라 PVC를 분류하였다. 제안한 방법의 우수성을 입증하기 위해 PVC가 30개 이상 포함된 MIT-BIH 9개의 레코드를 대상으로 한 R파의 평균 검출율은 99.02%의 성능을 나타내었으며, PVC 부정맥은 각각 93.72%의 평균 분류율을 나타내었다.