• 대한의용생체공학회:의공학회지
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• 제16권3호
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• pp.359-366
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• 1995

The parameter, B/A, quantifies nonlinearity of the pressure-density relationship of propagation medium. This study investigated quantitative evaluation technique for healing fractured bones using this ultrasonic nonlinear parameter, B/A, obtained by the second harmonic amplitude method. A series of fundamental experiments were performed on cylinder phantoms made of aluminium, which demonstrated potential capability of nonlinear parameter B/A in the diagnosis of healing fractured bones using ultrasound.

• 한국음향학회지
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• 제19권4호
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• pp.101-106
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• 2000

광대역 고분자 초음파 변환기를 이용한 초음파 비선형 파라메타 B/A 측정장치를 이용하여 생체조직에서 지방질의 농도에 대한 B/A의 의존성을 알아보기 위하여 계란의 흰자와 노른자의 혼합에 대하여 조사하였다. 이들 두 성분에 대한 음속과 밀도가 서로 1% 정도임에도 불구하고 yoshizuni등에 의해 제시된 선형성보다 이차적 의존성이 더 있음을 확인하였다. 이것은 생체조직을 fat과 nonfat의 두 부분으로 나누어 지방질의 농도에 대한 초음파 비선형 파라메타 B/A와 음속의 크기에 대하여 본 연구에서 제시한 이론식과 잘 일치하였다. 또한 지방질이 없는 skim milk의 다양한 용해도 성분에 대한 B/A와 음속을 측정한 결과 용해도의 농도가 클수록 B/A와 음속의 값이 커짐을 알 수 있었으며, 이들에 영향을 주는 것은 단백질 등으로 예상된다.

• 전자공학회논문지B
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• 제28B권5호
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• pp.335-342
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• 1991

A real-tme nonlinear parameter tomography is pumping wave method. This tomorgraphy has a merit which requires no 180$^{\circ}$ projection datum, while the ray-bending effect is remrkably remained on the reconstructed image. In this paper we intend to compensate this ray-bending effect using the perturbation method. Impulsive pumping wave makes derived compensative term simple form, nad the compensative image is easily obtained. We perform computer simulation to confirm the improvement of corrected imate.

• 전자공학회논문지B
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• 제33B권5호
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• pp.1-9
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• 1996

In this paper, a parameter identification method for a discrete-time linear system using multi-layer neural network is proposed. The parameters are identified with the combination of weights and the output of neuraons of a neural network, which can be used for a linear and a nonlinear controller. An adaptive output tracking architecture is designed for the linear controller. And, the nonlinear controller. A sliding mode control law is applied to the stabilizing the nonlinear controller such that output errors can be reduced. The effectiveness of the proposed control scheme is illustrated through simulations.

• 대한방사선기술학회지:방사선기술과학
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• 제24권1호
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• pp.43-48
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• 2001

This study deals with the relationship between the magnitude of ultrasonic nonlinear parameter B/A, and sound speed of amount of fat present in biological media to measure B/A system using a wide band ultrasonic transducer. To represent this case, mixtures of egg whites and egg yolk were studied. Even though the differences in density and sound speed of the two egg components were in the range of 1%, B/A increase parabolically as a function of the fat density, which is not in agreement with the Yoshizumi et al's suggestion. In skim milk that does not contain fat, both the B/A and the sound speed increase with the solubility. It is considered that protein could affect these values.

• 대한수학회보
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• 제54권4호
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• pp.1309-1321
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• 2017

In this paper, we present a practical Mittag Leffler stability for fractional-order nonlinear systems depending on a parameter. A sufficient condition on practical Mittag Leffler stability is given by using a Lyapunov function. In addition, we study the problem of stability and stabilization for some classes of fractional-order systems.

• Journal of applied mathematics & informatics
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• 제42권1호
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• pp.213-221
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• 2024

A family of sixth-order multiple-root solver have been developed and the special case of weight function is investigated. The dynamical analysis of selected iterative schemes with uniparametric polynomial weight function are studied using Möbius conjugacy map applied to the form ((z - A)(z - B))^m and the stability surfaces of the strange fixed points for the conjugacy map are displayed. The numerical results are shown through various parameter spaces.

• 비파괴검사학회지
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• 제21권5호
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• pp.549-555
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• 2001

초음파법은 산업설비의 열화 정도나 결함을 평가하기 용이한 비파괴적 방법이다. 본 연구에서는 1Cr-1Mo-0.25V을 $630^{\circ}C$에서 등온열화처리하여 4개의 시편을 준비하였다. 이를 사용하여 초음파의 속도, 감쇠계수를 측정하여 재료의 열화를 평가하였으며, 배진동의 발생효률을 나타내는 비선형파라미터를 이용하여 재료의 열화정도를 평가하였다. 감쇠계수와 비선형파라미터는 열화가 진행될 수록 증가하였으며, 특히 1,820 시간 열화시편의 배진동 진폭은 원시시편의 배진동 진폭과 비교 시 20dB이상 증가하였나. 그러나 열화정도에 따른 속도의 변화는 거의 없는 것으로 나타났다. 본 연구결과에서 감쇠계수와 비선형파라미터는 재질 열화에 민감하게 반응하는 파라미터였으며, 재질 열화도를 평가하기에 적절한 파라미터인 것으로 사료된다.

• 한국음향학회:학술대회논문집
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• 한국음향학회 2004년도 추계학술발표대회논문집 제23권 2호
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• pp.429-432
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• 2004

Nonlinear acoustic responses of water-saturated sediments are very important to understand nonlinear phenomena of gassy ocean sediments. Especially, the second harmonic, the sum and the difference frequency acoustic waves in water-saturated sediments can provide practical criteria to estimate the nonlinear parameter of gassy sediments. In this paper, the difference frequency acoustic wave in water-saturated sandy sediment was observed in a water tank experiment with a pulse transmission technique. Its pressure level was 12 dB higher than the background noise level at a maximum undistorted driving pressure of source acoustic transducer. The experimental results were compared with a theoretical estimation of the parametric acoustic array. The nonlinear parameter of water-saturated sandy sediment was also estimated as 73 with their comparison. This value can be utilized as the background information to estimate gas void fraction in the water-saturated gassy sandy sediment.

• 대한수학회지
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• 제41권6호
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• pp.957-976
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• 2004

It is well known that the application of the nonlinear coordinate transformations is useful for efficient numerical evaluation of weakly singular integrals. In this paper, we consider the trapezoidal rule combined with a nonlinear transformation $\Omega$$_{m}$(b;$\chi$), containing a parameter b, proposed first by Yun [14]. It is shown that the trapezoidal rule with the transformation $\Omega$$_{m}$(b;$\chi$), like the case of the Gauss-Legendre quadrature rule, can improve the asymptotic truncation error by using a moderately large b. By several examples, we compare the numerical results of the present method with those of some existing methods. This shows the superiority of the transformation $\Omega$$_{m}$(b;$\chi$).TEX>).