• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.371-376
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• 2003

In general, the electronic forklift driven by DC motor drive system is used in the industrial field. Classically, the DC motor is controlled by speed control using proportion control method, by output torque following the load on the plane like a manual operation. But in the industrial field, the electronic forklift is demanded the robust drive mode. Some cases of the mode, there are trouble in torque and speed control following slope capacity. The control is sensitive concerning with slope angle and output speed, various control method is studied for stability of speed control. We apply speed controller for the self-tuning using DSP(TMS320F240) as main controller for high speed processor, embody dynamic characteristic of control compared the PI control to the fuzzy control.

• Journal of Electrical Engineering and Technology
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• v.6 no.1
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• pp.48-58
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• 2011

In this paper, an attempt has been made to design the current and speed proportional and integral (PI) regulators of self-commutating current source inverter-fed induction motor drive having capacitors at the machine end and to investigate the transient performance of the same for step changes in reference speed. The mathematical model of the complete drive system is developed in closed loop, and the characteristic equations of the systems are derived using perturbation about steady-state operating point in order to develop the characteristic equations. The D-partition technique is used for finding the stable region in the parametric plane. Frequency scanning technique is used to confirm the stability region. Final selection of the regulator parameters is done by comparing the transient response of the current and speed loops for step variations in reference. The performance of the drive is observed analytically through MATLAB simulation.

• Journal of the Korean Mathematical Society
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• v.40 no.6
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• pp.977-998
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• 2003

Let k be an imaginary quadratic field, η the complex upper half plane, and let $\tau$ $\in$ η $textsc{k}$, p = $e^{{\pi}i{\tau}}$. In this article, using the infinite product formulas for g2 and g3, we prove that values of certain infinite products are transcendental whenever $\tau$ are imaginary quadratic. And we derive analogous results of Berndt-Chan-Zhang ([4]). Also we find the values of (equation omitted) when we know j($\tau$). And we construct an elliptic curve E : $y^2$ = $x^3$ ＋ 3 $x^2$ ＋ {3-(j/256)}x ＋ 1 with j = j($\tau$) $\neq$ 0 and P = (equation omitted) $\in$ E.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.65-68
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• 1998

The mechanism of response time and viewing angle in in-plane switching ( IPS ) liquid crystal display ( LCD ) were investigated. The response time of photo-aligned IPS-LCD is fast compared with rubbing-aligned IPS-LCD on polyimide ( PI ) surface. The decay time $\tau$$\_$d/ is decreased with increasing the azimuthal anchoring energy A $\psi$ due to the steric interaction between the LC molecules and side chain of polymer. The viewing angle of IPS-LCD is increased by using photo-depolymerizatin method ; about ${\pm}$70$^{\circ}$at all direction.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2552-2556
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• 2005

In general, the forklift driven by DC motor drive system is used in the industrial field. Classically, the DC motor is controlled by current control using proportion control method, by output torque following the load on the plane like a manual operation. But in the industrial field, the forklift is demanded the robust drive mode. Some cases of the mode, there aretrouble in torque control following slope capacity. The control is sensitive concerning about slope angle and output speed, various control method is studied for stability of speed control. In this paper, I apply current control for the self-tuning using the fuzzy controller to obtain robust, stable speed control and use stable, high efficiency control using DSP as main controller for high speed processor, embody dynamic characteristic of control compared the PI controller to the fuzzy controller.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.55.4-55.4
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• 2016

We observed 10 Class I sources as part of the IGRINS (Immersion GRating INfrared Spectroscoph) Legacy Program, "IGRINS Survey of Protoplanetary Disks (PI: Jeong-Eun Lee)". Unlike other Class I sources, IRAS 16316-1540 shows broad absorption features in the near-infrared spectra (H and K bands). The broadened absorption features have been detected toward FU Orionis-type objects. Boxy or double-peaked absorption profiles can be produced by a Keplerian disk that has the hot mid-plane heated by a burst mass accretion. We could fit the broad absorption features of IRAS 16316-1540 with a K5 V template stellar spectrum convolved with a disk rotation profile of 45 km s-1. Therefore, rotationally broadened absorption features detected in this Class I source suggest that the episodic accretion process occurs from the early stage of star formation.

• Bulletin of the Korean Mathematical Society
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• v.34 no.4
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• pp.549-560
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• 1997

For positive integers $n_i \geq 2, i = 1, 2, 3, 4$, such that $\Sigma \frac{n_i}{1} < 2$, there exists a quadrilateral $P = P_1 P_2 P_3 P_4$ in the hyperbolic plane $H^2$ with the interior angle $\frac{n_i}{\pi}$ at $P_i$. Let $\Gamma \subset Isom(H^2)$ be the (discrete) group generated by reflections in each side of $P$. Then the quotient space $H^2/\gamma$ is a differentiable orbifold of type $(^* n_1 n_2 n_3 n_4)$. It will be shown that the deformation space of $Rp^2$-structures on this orbifold can be mapped continuously and bijectively onto the cell of dimension 4 - \left$\mid$ {i$\mid$n_i = 2} \right$\mid$$.

• Bulletin of the Korean Mathematical Society
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• v.51 no.5
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• pp.1551-1559
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• 2014

We consider functions that map the open unit disc conformally onto the complement of an unbounded convex set with opening angle ${\pi}{\alpha}$, ${\alpha}{\in}(1,2]$, at infinity. We derive the exact interval for the variability of the real Taylor coefficients of these functions and we prove that the corresponding complex Taylor coefficients of such functions are contained in certain discs lying in the right half plane. In addition, we also determine generalized central functions for the aforesaid class of functions.

• Journal of the Korean Mathematical Society
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• v.45 no.5
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• pp.1379-1391
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• 2008

Let k be an imaginary quadratic field, ${\eta}$ the complex upper half plane, and let ${\tau}{\in}{\eta}{\cap}k,\;q=e^{{\pi}{i}{\tau}}$. For n, t ${\in}{\mathbb{Z}}^+$ with $1{\leq}t{\leq}n-1$, set n=${\delta}{\cdot}2^{\iota}$(${\delta}$=2, 3, 5, 7, 9, 13, 15) with ${\iota}{\geq}0$ integer. Then we show that $q{\frac}{n}{12}-{\frac}{t}{2}+{\frac}{t^2}{2n}{\prod}_{m=1}^{\infty}(1-q^{nm-t})(1-q^{{nm}-(n-t)})$ are algebraic numbers.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.1
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• pp.88-99
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• 1998

In assembly, misalignment must be detected and compensated for during the mating period, regardless of the complexity of the cross-sectional shape. To this end, we propose a novel omnidirectional image sensing system for assembling parts with complicated shapes(OISSA) and its feasibility for detecting the misalignment between mating parts is shown by a series of simulations. This system encompasses a camera with an optical unit attached to the front of the camera. The optical unit consists of a pair of plane mirrors and a pair of conic mirrors. Utilizing the proposed sensing system, a 2$\pi$ coaxial image of the misalignment along the mating boundary interface between mating parts can be immediately obtained without experiencing self-occlusion.