• Journal of Institute of Control, Robotics and Systems
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• v.11 no.11
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• pp.895-900
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• 2005

We derive a linear matrix inequality(LMI) condition guaranteeing that any invariant zeros of a triple (A, B, C) lie in the open left half plane of the complex plane, i.e. $C(sI-A)^{-1}B$ is minimum phase. The LMI condition is equivalent to a certain constrained Lyapunov matrix equation which can be found in many results relating to stability analysis or control design. We show that the LMI condition can be used to simplify various control engineering problems such as a dynamic output feedback control problem, a variable structure static output feedback control problem, and a nonlinear system observer design problem. Finally, we give some numerical examples.

• Bulletin of the Korean Mathematical Society
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• v.39 no.2
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• pp.269-276
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• 2002

Let E be a real Banach space. Let T : E longrightarrow E be a map with F(T) : = { x $\in$ E : Tx = x} $\neq$ 0 and satisfying the accretive-type condition $\lambda\$\mid$x-Tx\$\mid$^2$, for all $x\inE,\;x^*\inf(T)\;and\;\lambda >0$. We prove some necessary and sufficient conditions for the convergence of the Mann iterative sequence to a fixed point of T.

• Journal of the Korean Statistical Society
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• v.24 no.1
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• pp.225-231
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• 1995

An eventual uniform equicontinuity condition is investigated in the context of the uniform central limit theorem (UCLT) for continuous martingales. We assume the usual intergrability condition on metric entropy. We establish an exponential inequality for a martingales. Then we use the chaining lemma of Pollard (1984) to prove an eventual uniform equicontinuity which is a sufficient condition of UCLT. We apply the result to approximate a stochastic integral with respect to a martingale to that of a Brownian motion.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.1167-1170
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• 1999

We consider a negative unity feedback control system in which a controller and a given minimum phase transfer function are in cascade. This paper present a sufficient condition for the existence of a constant gain controller under which the overall closed loop characteristic polynomial is stable. This sufficient condition is based on Lehnigk's lemmas.

• Journal of applied mathematics & informatics
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• v.22 no.1_2
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• pp.223-235
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• 2006

By applying the Landau-type transformation, we transform a Stefan problem with nonlinear free boundary condition into a system consisting of a parabolic equation and the ordinary differential equations. Fully discrete finite element method is developed to approximate the solution of a system of a parabolic equation and the ordinary differential equations. We derive optimal orders of convergence of fully discrete approximations in $L_2,\;H^1$ and $H^2$ normed spaces.

• Communications of the Korean Mathematical Society
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• v.14 no.2
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• pp.441-447
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• 1999

A free boundary problem is derived from a singular limit system of a reaction diffusion equation whose reaction terms are bistable type. In this paper, we shall consider a free boundary problem with two layers satisfying the zero flux boundary condition and shall show that the Hopf bifurcation can not occur as a parameter varies.

• Korean Journal of Applied Biomechanics
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• v.12 no.1
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• pp.47-61
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• 2002

The purpose of this study was to determined the force and moment of the ankle and the knee joint at different step length relative to the length of the lower extremity during a steady running. Six digital cameras(Qualisis) and a forceplatform(A.M.T.I) were used to obtain the kinematic data of the segments and kinetic data on the running at speed of 5.18m/s. The force and moment measured from six subjects participated in this study were limited to the support phase and their values were averaged at the moment of heel strike, mid stance, and toe off of a running for making a comparison between the condition 1(relative step length 1.1) and the condition 2(relative step length 1.4). It was concluded that internal forces except mediolateral force of the condition 2 were greater in the ankle and the knee joint than those of the condition 1, but all moments of condition 2 were greater from the descriptive statistic point of view. For the future study, it was needed to consider a number of subjects, a various running speed, and a individual step preference for applying generally results to the running strategy.

• Journal of Korean Society of Rural Planning
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• v.8 no.3 s.17
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• pp.15-23
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• 2002

The study was performed to establish a criteria which can be served as a reference in preparing upland direct payment program in Korea, by analyzing WTO agreement content and by studying about direct payment program in EU and Japan and by slope analysis using GIS. Slope analysis using GIS was operated by 1/5000 digital map, and a field survey was put in practice, and merits and demerits were deduced. We can propose a criteria to select the disadvantaged areas in aspects of physical condition, farming condition. and economical and social condition is important to regionally classify "less-favored area(LFA)" and LFA division by economical and social condition is needed to identify legally. Therefore, we would propose a criteria which can select "less-favored area" by analyzing WTO agreement content and by studying about direct payment program in EU and Japan and slope analysis using GIS and a field survey.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.779-782
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• 1996

Repetitive control is a proposed control strategy in view of the internal model principle and achieves a high accuracy asymptotic tracking property by implementing a model that generates the periodic signals of period into the closed-loop system. Since the repetitive control system contains a periodic signal generator with positive feedback loop, which reduces the stability margin, in the overall closed-loop system, the stability of the closed-loop system should be considered as an important problem. In case that a real system has plant uncertainties which are not represented through modeling, the robust stability problem of the repetitive control system has not been considered sufficiently. In this paper, we propose the robust stability condition for the system with modeling uncertainty. The proposed robust stability condition will be obtained using the robust performance condition in the H$_{\infty}$ control. Moreover, by use of the proposed robust stability condition, we propose a procedure that designs a repetitive controller and a feedback controller simultaneously which can stabilize the overall closed-loop system robustly and which can also do the closedloop system without repetitive controller..

• Ocean Systems Engineering
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• v.5 no.1
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• pp.1-19
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• 2015

The water jetting system for a jack-up spudcan requires the suitable design considering the platform/spudcan particulars, environments, and soil conditions, either the surficial clay or surficial sand. The usage of water jetting depends critically on soil conditions. The water jetting is usually used for the smooth and fast extraction of the spudcan in the surficial clay condition. It is also required for inserting spudcan up to the required depth in the surficial sand condition, which is investigated in this paper. Especially, it should be very careful to use the water jetting during an installation of spudcan in the surficial sand condition, because there is a risk of overturning accident related to the punch-through. Therefore, in this study, the effect of water jetting flow rate and time on the change of soil properties and penetration resistance is analyzed to better understand their interactions and correlations when inserting the spudcan with water jetting in surficial sand condition. For the investigation, a wind turbine installation jack-up rig (WTIJ) is selected as the target platform and the multi layered soil (surficial sand overlaying clays) is considered as the soil condition. The environmental loading and soil-structure interaction (SSI) analysis are performed by using CHARM3D and ANSYS. This kind of investigation and simulation is needed to decide the proper water jetting flow rate and time of spudcan for the given design condition.