• Title/Summary/Keyword: S−stable

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Robust PID $\times$ (n-1) Stage PD Controller

  • Numsomran, Arjin;Julsereewong, Prasit;Ukakimaparn, Prapart;Trisuwannawat, Thanit;Tirasesth, Kitti
    • 제어로봇시스템학회:학술대회논문집
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    • 1999.10a
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    • pp.298-301
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    • 1999
  • This paper presents a design technique based on the root locus method fur a class of $n^{th}$ order plants using PID (Proportional-Integral-Derivative) x (n-1) stage PD controller. It is intended to satisfy both transient and steady state response specifications. This controller can be used instead of a conventional PID controller for the higher order plants to obtain better performances. The controlled system is approximated as a stable and robust second order controlled system. Only adjusting the controller gain, the desired performances of the controlled system are satisfied. For the stable plant including the plant with small dead time, the controlled system is made robustly stable. In case of the unstable plant, when the controller gain is adjusted higher than the critical value, the unstable plant can also be made stable. Robustness properties given by this controller proposed in this paper have also been demonstrated by numerical examples.

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A study on the Design of a stable Substrate Bias Generator for Low power DRAM's (DRAM 의 저전력 구현을 위한 안정한 기판전압 발생기 설계에 관한 연구)

  • 곽승욱;성양현곽계달
    • Proceedings of the IEEK Conference
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    • 1998.10a
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    • pp.703-706
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    • 1998
  • This paper presents an efficient substrate-bias generator(SBG)for low-power, high-density DRAM's The proposed SBG can supply stable voltage with switching the supply voltage of driving circuit, and it can substitude the small capacitance for the large capacitance. The charge pumping circuit of the SBG suffere no VT loss and is to be applicable to low-voltage DRAM's. Also it can reduce the power consumption to make VBB because of it's high pumping efficiency. Using biasing voltage with positive temperature coefficient, VBB level detecting circuit can detect constant value of VBB against temperature variation. VBB level during VBB maintaining period varies 0.19% and the power dissipation during this period is 0.16mw. Charge pumping circuit can make VBB level up to -1.47V using VCC-1.5V, and do charge pumping operation one and half faster than the conventional ones. The temperature dependency of the VBB level detecting circuit is 0.34%. Therefore the proposed SBG is expected to supply a stable VBB with less power consumption when it is used in low power DRAM's.

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Relationship Between Soil Water-Stable Aggregates and Physico-chemical Soil Properties (토양 내수성 입단과 토양특성과의 관계)

  • Hyun, Byung-Keun;Jung, Sug-Jae;Song, Kwan-Cheol;Sonn, Yeon-Kyo;Jung, Won-Kyo
    • Korean Journal of Soil Science and Fertilizer
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    • v.40 no.1
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    • pp.57-63
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    • 2007
  • Soil aggregation has been considered as an important factor not only for increasing soil productivity and soil quality but also improving nutrient use availability and water use efficiency. However, the relationship between soil aggregation and soil properties hasn't well reported for Korean soils. Objective of this research was to identify the relationship among soil water-stable aggregate (WSA), soil properties and soil dispersion ratio. Soil samples were analyzed for water-stable aggregate, Middleton's dispersion ratio, and soil physical and chemical properties. Water-stable aggregate was significantly correlated to soil textural properties, soil organic matter, and exchangeable cations. Middleton's dispersion ratio was significantly correlated with water-stable aggregate ($r=-0.76^{***}$). Regression equation for water-stable aggregate was estimated by Middleton's dispersion ratio (Y=-0.79X + 96.49; $r^2=0.58^{**}$). In this research, we conclude that water-stable aggregate was significantly correlated with some soil properties and was able to be estimated by rapid and easily measurable Middleton's dispersion ratio.

SOME REMARKS ON STABLE MINIMAL SURFACES IN THE CRITICAL POINT OF THE TOTAL SCALAR CURVATURE

  • Hwang, Seung-Su
    • Communications of the Korean Mathematical Society
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    • v.23 no.4
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    • pp.587-595
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    • 2008
  • It is well known that critical points of the total scalar curvature functional S on the space of all smooth Riemannian structures of volume 1 on a compact manifold M are exactly the Einstein metrics. When the domain of S is restricted to the space of constant scalar curvature metrics, there has been a conjecture that a critical point is isometric to a standard sphere. In this paper we investigate the relationship between the first Betti number and stable minimal surfaces, and study the analytic properties of stable minimal surfaces in M for n = 3.

Can a Skier Make a Circular Turn without any Active Movement?

  • Youn, Sun-Hyun
    • Journal of the Korean Physical Society
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    • v.73 no.10
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    • pp.1410-1419
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    • 2018
  • A skier's motion was analyzed by a simple model consist of point mass m and a single rod connected to a single ski plate. We studied the conditions for the stable ski turn as functions of the linear velocity and the radius of the turn. The solutions for the stable ski turn in our model do not require any extra skier's movement to complete a stable circular turn. The solution may then give the skier the most comfortable skiing method without any active movement to control the ski. The generalized force supporting the point mass from the ski plate was calculated. We obtained the force from the ground (rebound force) without any geometrical structure of the ski plate. Adding an active movement to the direction of the ski plate, the conditions for the stable ski turn were also analyzed. Our result gives some insight for the skier who wants to develop technique.

A Study on Stable Grasping Motion Control of Dual-Finger (듀얼-핑거의 안정적 파지 운동 제어에 관한 연구)

  • Um Hyuk;Choi Jong-Hwan;Kim Seung-Soo;Han Hyun-Yong;Yang Soon-Yong;Lee Jin-Gul
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.14 no.4
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    • pp.81-88
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    • 2005
  • This paper attempts to derive the dynamic model of handling tasks in finger robot which grasps stable and manipulates a rigid object with some dexterity. Firstly, a set of differential equation describing dynamics of the manipulators and object together with geometric constraint of tight area-contacts is formulated by Lagrange's equation. Secondly, the roblems of controlling both the forces of pressing object and the rotation angle of the object under the geometric constraints are discussed. The effect of geometric constraints of area-contacts between the link's end-effector and the object is analyzed and the model based on the differential-algebraic equations is presented. In this paper, the control method for dynamic stable grasping and enhancing dexterity in manipulating things is proposed. It is illustrated by computer simulation and the experiment that the control system gives the performance improvement in the dynamic stable grasping and nimble manipulating of the dual fingers robot with soft tips.

Stable Channel Design for the Gravel-bed River Considering Design Constraints (설계구속인자를 고려한 자갈하상 하천의 안정하도 설계)

  • Ji, Un;Jang, Eun-Kyung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.4
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    • pp.2860-2867
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    • 2015
  • Stable channel design is to determine the width, depth and slope for satisfying the condition that the upstream incoming sediment rate is equal to the sediment transport rate at the design channel. Therefore, the most sensitive variable when designing a stable channel is the selection of a sediment transport equation applied for the channel design. Especially if in the case of gravel beds the designer uses the equation developed by using the data of sand rivers, the calculation result of the stable channel section has large errors. In this study, the stable channel design has been applied to the gravel bed river using the previous stable channel design program with newly added the sediment transport equation for gravel beds; and the stable channel section considering design constraints has been produced by using the analytical method. As results, in the case of the application with the fixed width, the depth predicted by Ackers and White's equation was the shallowest and Meyer-Peter and $M\ddot{u}ller's$ equation was 0.8 m deeper than the current section of 2.4 m. In the case of the application with the fixed depth, the width predicted by Engelund and Hansen's equation was twice wider than the current section and by Meyer-Peter and $M\ddot{u}ller's$ equation was 20 m wider than the current section of 44 m.

Signal Detection Based on a Decreasing Exponential Function in Alpha-Stable Distributed Noise

  • Luo, Jinjun;Wang, Shilian;Zhang, Eryang
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.12 no.1
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    • pp.269-286
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    • 2018
  • Signal detection in symmetric alpha-stable ($S{\alpha}S$) distributed noise is a challenging problem. This paper proposes a detector based on a decreasing exponential function (DEF). The DEF detector can effectively suppress the impulsive noise and achieve good performance in the presence of $S{\alpha}S$ noise. The analytical expressions of the detection and false alarm probabilities of the DEF detector are derived, and the parameter optimization for the detector is discussed. A performance analysis shows that the DEF detector has much lower computational complexity than the Gaussian kernelized energy detector (GKED), and it performs better than the latter in $S{\alpha}S$ noise with small characteristic exponent values. In addition, the DEF detector outperforms the fractional lower order moment (FLOM)-based detector in $S{\alpha}S$ noise for most characteristic exponent values with the same order of magnitude of computational complexity.

STABLE f-HARMONIC MAPS ON SPHERE

  • CHERIF, AHMED MOHAMMED;DJAA, MUSTAPHA;ZEGGA, KADDOUR
    • Communications of the Korean Mathematical Society
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    • v.30 no.4
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    • pp.471-479
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    • 2015
  • In this paper, we prove that any stable f-harmonic map ${\psi}$ from ${\mathbb{S}}^2$ to N is a holomorphic or anti-holomorphic map, where N is a $K{\ddot{a}}hlerian$ manifold with non-positive holomorphic bisectional curvature and f is a smooth positive function on the sphere ${\mathbb{S}}^2$with Hess $f{\leq}0$. We also prove that any stable f-harmonic map ${\psi}$ from sphere ${\mathbb{S}}^n$ (n > 2) to Riemannian manifold N is constant.