• 동력기계공학회지
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• 제3권4호
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• pp.79-85
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• 1999

The magnetic levitation system is utilized in the magnetic bearing of high-speed rotor system because of little friction, no lubrication, no noise and so on. The magnetic levitation system needs the feedback controller for the stabilization of system, and gap sensors are generally used to measure the gap. The use of sensor easily goes into troublesome caused by sensor failure discord between the measurement point and the control point etc. This paper gives a controller design method of magnetic levitation system which satisfies the given $H_{\infty}$ control performance and the robust stability of the presence of physical parameter perturbations. To the end, we investigated the validity of the designed controller through results of simulation.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.54-60
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• 2006

This study looks over the relation between propeller and noise in ship stern structure. Near field noise and vibration measurements are compared with the analytical results using wave number method. To avoid singularity in wave number integration method, fast field method is introduced. Analytical results show that main transmission mechanism of high frequency noise is structure-borne type and that of low frequency noise is a air-borne type.

• 한국해양공학회지
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• 제4권1호
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• pp.62-70
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• 1990

Cauchy의 적분공식을 복소속도(complex velocity)에 적용하여 포텐시얼 유동을 해석하는 복소경계요소법이 개발되었다. 이 결과로 얻어지는 적분방정식은 경계면에서의 접선속도(tangential velocity)와 법선속도(normal velocity)의 함수로 주어진다. 자유수면에서의 접선속도의 시간변화(evolution of tangential velocity)를 수식화하기 위하여 새로운 비선형 동역학적 자유수면경계조건(nonlinear dynamic free surface boundary condition)을 유도하였다. 복소포텐시얼 대신 복소속도를 이용하는 이 방법은 유장내의 특이점(field singularity)을 용이하게 고려할 수 있으며, 수치미분없이 직접 경계면에서의 유속을 해로서 구하게 된다. 그러나 자유수면이 존재하는 문제의 경우에는, 자유수면에서의 동역학적 경계조건을 만족 시키기 위한 계산과정에 접선 벡타의 변화량을 추정하는 것이 포함되게 되어, 계산과정이 다소 복잡하게 된다.

• 대한수학회논문집
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• 제32권1호
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• pp.29-38
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• 2017

The main objective of this paper is to establish certain unified integral formula involving the product of the generalized Mittag-Leffler type function $E^{({\gamma}_j),(l_j)}_{({\rho}_j),{\lambda}}[z_1,{\ldots},z_r]$ and the Srivastava's polynomials $S^m_n[x]$. We also show how the main result here is general by demonstrating some interesting special cases.

• Journal of the Korean Statistical Society
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• 제24권1호
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• pp.197-218
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• 1995

We first consider the random censorship model of survival analysis. Efron (1981) introduced two equivalent bootstrap methods for censored data. We propose a new bootstrap scheme, called Method 3, that acts conditionally on the censoring pattern when making inference about aspects of the unknown life-time distribution F. This article contains (a) a motivation for this refined bootstrap scheme ; (b) a proof that the bootstrapped Kaplan-Meier estimatro fo F formed by Method 3 has the same limiting distribution as the one by Efron's approach ; (c) description of and report on simulation studies assessing the small-sample performance of the Method 3 ; (d) an illustration on some Danish data. We also consider the model in which the survival times are censered by death times due to other caused and also by known fixed constants, and propose an appropriate bootstrap method for that model. This bootstrap method is a readily modified version of the Method 3.

• Journal of applied mathematics & informatics
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• 제6권2호
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• pp.329-368
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• 1999

This paper surveys recent remarkable progress in the study of potential theory for symmetric stable processes. It also contains new results on the two-sided estimates for Green functions Poisson kernels and Martin kernels of discontinuous symmetric $alpha$ -stable process in bounded $C^{1,1}$ open sets. The new results give ex-plicit information on how the comparing constants depend on pa-rametrer $alpha$ and consequently recover the green function and Poisson kernel estimates for Brownian motion by passing $alpha{\uparrow}2$. In addition to these new estimates this paper surveys recent progress in the study of notions of harmonicity integral representation of harmonic func-tions boundary harnack inequality conditional gauge and intrinsic ultracontractivity for symmetric stable processes. Here is a table of contents.

• Journal of applied mathematics & informatics
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• 제28권1_2호
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• pp.473-485
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• 2010

We consider the differential equation $$(x^2\;-\;1)u_{xx}\;+\;2xyu_{xy}\;+\;(y^2\;-\;1)u_{yy}\;+\;gxu_x\;+\;gyu_y\;=\;\lambda_nu,\;(*)$$ where $\lambda_n\;=\;n(n\;+\;9\;-\;1)$. We show that the differential equation (*) has a polynomial set as solutions if $g\;{\neq}\;-1$, -3, -5, $\cdots$. Also, we construct an orthogonalizing distributional weight for g < 1 and $g\;{\neq}\;1$, 0, -1, $\cdots$ by regularizing a one-dimensional integral with a singularity on the endpoint of the interval.

• Journal of Electrical Engineering and Technology
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• 제11권2호
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• pp.490-498
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• 2016

Proportional Integral Derivative (PID) controller tuning is an area of interest for researchers in many areas of science and engineering. This paper presents a new algorithm for PID controller tuning based on a combination of bacteria foraging and particle swarm optimization. BFO algorithm has recently emerged as a very powerful technique for real parameter optimization. To overcome delay in an optimization, combine the features of BFOA and PSO for tuning the PID controller. This new algorithm is proposed to combine both the algorithms to get better optimization values. The real time prototype model of paper machine is designed and controlled by using PIC microcontroller embedded with the programming in C language.

• 전기학회논문지P
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• 제60권2호
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• pp.72-75
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• 2011

In this paper, the voltage across the LED system supplied by positive voltage of power supply system the power consumption of the LED itself, and uses a lot of transformers and analog devices, such as converter startup problems and constant temperature even when the voltage driving abnormally LED current in the destruction caused by the flow of a lot of problems can occur. In this paper, we obtain the technology of consistent current using PWM(pulse width modulation) mode in order to minimize analog devices and eventually discuss the technology to develop consistent output converter using power drive IC.

• 대한수학회보
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• 제47권6호
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• pp.1181-1188
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• 2010

q-Volkenborn integrals ([8]) and fermionic invariant q-integrals ([12]) are introduced by T. Kim. By using these integrals, Euler q-zeta functions are introduced by T. Kim ([18]). Then, by using the Euler q-zeta functions, S.-H. Rim, S. J. Lee, E. J. Moon, and J. H. Jin ([25]) studied q-Genocchi zeta functions. And also Y. H. Kim, W. Kim, and C. S. Ryoo ([7]) investigated twisted q-zeta functions and their applications. In this paper, we consider the q-analogue of twisted Lerch type Euler zeta functions defined by $${\varsigma}E,q,\varepsilon(s)=[2]q \sum\limits_{n=0}^\infty\frac{(-1)^n\epsilon^nq^{sn}}{[n]_q}$$ where 0 < q < 1, $\mathfrak{R}$(s) > 1, $\varepsilon{\in}T_p$, which are compared with Euler q-zeta functions in the reference ([18]). Furthermore, we give the q-extensions of the above twisted Lerch type Euler zeta functions at negative integers which interpolate twisted q-Euler polynomials.