• Journal of Magnetics
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• 제16권2호
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• pp.120-124
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• 2011

The design of an air compressor-driving quadratic linear actuator in a fuel cell BOP system is studied using orthogonal techniques. The approach utilizes an orthogonal array for design of 'experiments', i.e. the scheme for numerical simulations using a finite element method. Eco-friendly energy is increasingly important due to the depletion of fossil fuels and environmental pollution. Among the new energy sources, fuel cell is spotlighted as renewable energy because it produces few dusts. The air compressor performance is directly related to the efficiency of the fuel cell BOP system has high power consumption. In this paper, an optimized technique using an orthogonal matrix is applied to the design problem to improve the performance of quadratic linear actuator.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.93-98
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• 2001

This paper studies on the design of an ILQ(Inverse Linear Quadratic optimal control) looper control system for hot strip mills. The looper which is placed between each stand plays an important role in controlling strip width by regulating strip tension variation generated from the velocity difference of main work rolls. The mathematical model for looper is firstly obtained by Taylor's linearization of nonlinear differential equations, where it is given as a linear and time invariant state-space equation. Secondly, a looper servo controller is designed by ILQ control algorithm, which is an inverse problem of LQ(Linear Quadratic optimal control) control. By tunning control gain arbitration parameters and time constants, it is shown that the ILQ looper servo controller has the performance that makes well to follow desired trajectories of both strip tension and looper angle.

• 대한수학교육학회지:학교수학
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• 제10권1호
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• pp.43-61
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• 2008

현 교육과정에서 이차함수 그래프에 관한 교수-학습은 대수적 조작에 의한 완전제곱형식으로의 변환을 강조하고 이미 선행한 일차함수의 그래프와는 무관하게 다루어지고 있다. 본 논문은 이차함수 그래프의 구조적 특성이라 할 수 있는 대칭성, 꼭지점 및 합동에 대한 기하적인 근거를 일차함수의 그래프에 기초하여 분석하고 이것의 결과를 구체적 이차함수에 대해 그 꼭지점의 좌표 및 절편을 찾는 데 적용한다. 본 연구는 이차함수 그래프의 구조적 특성을 일차함수의 그래프와 기하적으로 연결시키는 데 의의가 있으며 그 기하적인 과정은 완전제곱형식의 대수적 절차로 연결된다. 이러한 연결은 일차함수의 그래프에 대한 이해가 이차함수의 그래프에 대한 이해로 전이되어 이차함수에 대한 기하적인 이해를 넓히는 교수-학습방법이 될 수 있을 것이다.

• Journal of applied mathematics & informatics
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• 제13권1_2호
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• pp.53-65
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• 2003

Here we present a study of small-amplitude, shallow water waves on sloping beds. The beds considered in this analysis are linear and quadratic in nature. First we start with stating the relevant governing equations and boundary conditions for the theory of water waves. Once the complete prescription of the water-wave problem is available based on some assumptions (like inviscid, irrotational flow), we normalize it by introducing a suitable set of non-dimensional variables and then we scale the variables with respect to the amplitude parameter. This helps us to characterize the various types of approximation. In the process, a summary of equations that represent different approximations of the water-wave problem is stated. All the relevant equations are presented in rectangular Cartesian coordinates. Then we derive the equations and boundary conditions for small-amplitude and shallow water waves. Two specific types of bed are considered for our calculations. One is a bed with constant slope and the other bed has a quadratic form of surface. These are solved by using separation of variables method.

• 한국방사선학회논문지
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• 제9권6호
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• pp.417-420
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• 2015

본 연구는 탄소 빔의 분할조사 후 세포생존율 (Surviving Fraction, SF) 값에 따른 Linear-Quadratic model, Incomplete Repair model, Marchese model의 결과값을 비교하기 위해 진행하였다. 탄소 빔을 4fraction까지 조사한 후 얻은 세포생존율 값을 바탕으로 mathematica 프로그램 (ver 9.0)을 이용하여 각각의 모델로 결과값을 얻어 비교해 보았다. 그 결과 즉시 NB1RGB를 시딩한 값은 repair가 감안되지 않은 LQ 모델이 적합하였지만 fraction 시행한 후의 결과값은 오차를 보였다. 따라서 Potentially Lethal Damage Repair (PLDR)과 Sublethal Damage Repair (SLDR)의 발생을 각각 감안한 repair 모델을 이용하여 적합한지 판단하였다. 이를 바탕으로 탄소 빔의 분할 조사 시 LQ 모델에 각각의 repair의 양을 감안한 새로운 회복 관련 모델의 적용 가능성을 보고자 하였다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권5호
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• pp.873-887
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• 2015

The springing response of a large blunt ship was considered to be influenced by a second order interaction between the incoming irregular wave and the blunt geometry of the forebody of the ship. Little efforts have been made to simulate this complicated fluid-structure interaction phenomenon under irregular waves considering the second order effect; hence, the above mentioned premise still remains unproven. In this paper, efforts were made to quantify the second order effect between the wave and vibrating flexible ship structure by analyzing the experimental data obtained through the model basin test of the scaled-segmented model of a large blunt ship. To achieve this goal, the measured vertical bending moment and the wave elevation time history were analyzed using a higher order spectral analysis technique, where the quadratic interaction between the excitation and response was captured by the cross bispectrum of two randomly oscillating variables. The nonlinear response of the vibrating hull was expressed in terms of a quadratic Volterra series assuming that the wave excitation is Gaussian. The Volterra series was then orthogonalized using Barrett's procedure to remove the interference between the kernels of different orders. Both the linear and quadratic transfer functions of the given system were then derived based on a Fourier transform of the orthogonalized Volterra series. Finally, the response was decomposed into a linear and quadratic part to determine the contribution of the second order effect using the obtained linear and quadratic transfer functions of the system, combined with the given wave spectrum used in the experiment. The contribution of the second order effect on the springing response of the analyzed ship was almost comparable to the linear one in terms of its peak power near the resonance frequency.

• Kyungpook Mathematical Journal
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• 제49권4호
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• pp.691-700
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• 2009

We use the fixed alternative theorem to establish Hyers-Ulam-Rassias stability of the quadratic functional equation where functions map a linear space into a complete quasi p-normed space. Moreover, we will show that the continuity behavior of an approximately quadratic mapping, which is controlled by a suitable continuous function, implies the continuity of a unique quadratic function, which is a good approximation to the mapping. We also give a few applications of our results in some special cases.

• 제어로봇시스템학회논문지
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• 제4권1호
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• pp.1-9
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• 1998

This paper is focussed on the problem of robustly stabilizing a transformable linear time-varying system. The considered system is a class of state feedback transformable linear systems. First, the real linear time-varying system is transformed into the linear time invariant system composed with the time-invariant linear part and the time-varying uncertainty part. Second, the solution to a quadratic stabilization problem in the transformed linear system is give via' Lyapunov methods. Then this solution is used to construct a stabilizing linear control law for the real linear time-varying system.

• Journal of applied mathematics & informatics
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• 제22권1_2호
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• pp.133-148
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• 2006

This paper proposes a smoothing method for symmetric conic linear programming (SCLP). We first characterize the central path conditions for SCLP problems with the help of Chen-Harker-Kanzow-Smale smoothing function. A smoothing-type algorithm is constructed based on this characterization and the global convergence and locally quadratic convergence for the proposed algorithm are demonstrated.

• 한국토양비료학회지
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• 제43권2호
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• pp.174-179
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• 2010

본 연구에서는 사탕무의 시비반응을 합리적으로 해석하고 경제성 있는 최적 시비량 및 최대 수확량의 도출을 위한 방법을 검토하기 위하여 간척지 토양에서 수준별 질소비료와 돈분퇴비의 시용에 따른 사탕무의 시비반응을 조사하였다. 시비반응은 Quadratic model, Exponential model, Square root model 및 Linear response & plateau model을 이용하여 통계적으로 분석하였다. 토양 EC가 증가함에 따라 사탕무 지하부 생체중이 지수함수적으로 감소하였다. 질소비료 시비수준별 사탕무 지하부 생체량의 시비반응은 Linear response에서 결정계수 & plateau model ($R^2$)가 $0.92^{**}$로 고도의 통계적 유의성을 보였으며, Linear response & plateau model에서 최적 질소시비량 ($N_{opt}$)은 138 kg $ha^{-1}$으로 나타났다. 돈분퇴비의 시비반응은 Quadratic model에서 $0.99^{**}$의 유의성 있는 결정계수 ($R^2$)를 보였으며, 최적 퇴비시비량은 각각 9.17 tons $ha^{-1}$으로 나타났다. 상기 결과로 볼 때 사탕무에서 질소와 돈분퇴비의 시비반응을 적절히 평가하기 위해서는 각각 Linear response & plateau model과 Quadratic model을 이용하는 것이 합리적인 것으로 판단되었다.