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Identification problems of damped sine-Gordon equations with constant parameters
Junhong Ha,Shin-ichi Nakagiri 대한수학회 2002 대한수학회지 Vol.39 No.4
We study the problems of identification for the damped sine-Gordonequations with constant parameters. That is, we establish theexistence and necessary conditions for the optimal constantparameters based on the fundamental optimal control theory and thetransposition method studied in Lions and Magenes [ref{Lions-Magenes}].
RICCATI EQUATION IN QUADRATIC OPTIMAL CONTROL PROBLEM OF DAMPED SECOND ORDER SYSTEM
Ha, Junhong,Nakagiri, Shin-Ichi Korean Mathematical Society 2013 대한수학회지 Vol.50 No.1
This paper studies the properties of solutions of the Riccati equation arising from the quadratic optimal control problem of the general damped second order system. Using the semigroup theory, we establish the weak differential characterization of the Riccati equation for a general class of the second order distributed systems with arbitrary damping terms.
A find-path problem of a car-like vehicle
Ha, Junhong,Chun, Changbum 한국기술교육대학교 2004 論文集 Vol.10 No.2
A find-path problem is to find a path to adjust a moving object to move toward its target and avoid its obstacles. In this paper we solve a find path problem related to a car-like vehicle by using Lyapunov functions.
Junhong Ha,Shin-ichi Nakagiri 대한수학회 2004 대한수학회지 Vol.41 No.3
Identification problems for the system governed by abstract nonlinear damped second order evolution equations are studied. Since unknown parameters are included in the diffusion operator, we can not simply identify them by using the usual optimal control theories. In this paper we present how to solve our identi- fication problems via the method of transposition.
모멘트 방정식 방법에 의한 횡요 운동 방정식의 랜덤 해석
배준홍(Junhong Bai),권순홍(Sun Hong Kwon),하동대(Dong Dai Ha) 한국해양공학회 1992 韓國海洋工學會誌 Vol.6 No.2
In this paper an application technique of moment equation method to solution of nonlinear rolling equation of motion of ships is investigated. The exciting moment in the equation of rolling motion of ships is described as non-white noise. This non-white exciting moment is generated through use of a shaping filter. These coupled equations are used to generate moment equations. The nonstationary responses of the nonlinear system are obtained. The results are compared with those of a linear system.
Degradation pattern of SnO<sub>2</sub> nanowire field effect transistors
Na, Junhong,Huh, Junghwan,Park, Sung Chan,Kim, DaeIl,Kim, Dong Wook,Lee, Jae Woo,Hwang, In-Sung,Lee, Jong-Heun,Ha, Jeong Sook,Kim, Gyu Tae IOP Pub 2010 Nanotechnology Vol.21 No.48
<P>The degradation pattern of SnO<SUB>2</SUB> nanowire field effect transistors (FETs) was investigated by using an individual SnO<SUB>2</SUB> nanowire that was passivated in sections by either a PMMA (polymethylmethacrylate) or an Al<SUB>2</SUB>O<SUB>3</SUB> layer. The PMMA passivated section showed the best mobility performance with a significant positive shift in the threshold voltage. The distinctive two-dimensional <I>R</I><SUB>s</SUB>–μ diagram based on a serial resistor connected FET model suggested that this would be a useful tool for evaluating the efficiency for post-treatments that would improve the device performance of a single nanowire transistor. </P>
EQUATIONS OF MOTION FOR CRACKED BEAMS AND SHALLOW ARCHES
Semion Gutman,Junhong Ha,손수덕 경남대학교 수학교육과 2022 Nonlinear Functional Analysis and Applications Vol.27 No.2
Cracks in beams and shallow arches are modeled by massless rotational springs. First, we introduce a specially designed linear operator that “absorbs” the boundary conditions at the cracks. Then the equations of motion are derived from the first principles using the Extended Hamilton’s Principle, accounting for non-conservative forces. The variational formulation of the equations is stated in terms of the subdifferentials of the bending and axial potential energies. The equations are given in their abstract (weak), as well as in classical forms.
SHALLOW ARCHES WITH WEAK AND STRONG DAMPING
Gutman, Semion,Ha, Junhong Korean Mathematical Society 2017 대한수학회지 Vol.54 No.3
The paper develops a rigorous mathematical framework for the behavior of arch and membrane like structures. Our main goal is to incorporate moving point loads. Both the weak and the strong damping cases are considered. First, we prove the existence and the uniqueness of the solutions. Then it is shown that the solution in the weak damping case is the limit of the strong damping solutions, as the strong damping vanishes. The theory is applied to a car moving on a bridge.