• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2003.11a
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• pp.247-250
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• 2003

In this paper, the boundary element analysis of viscoelastic strain energy release ,ate G(t) for the cracked linear viscoelastic materials is attempted. This study proposes the G(t) equation and the calculating method of G(t) by time-domain boundary element analysis for the viscoelastic solids. The G(t) is defined as the derivative of the viscoelastic potential energy $\Pi(t)$ with respect to crack length a. Two example problems are presented to show the applicability of the proposed method to the analysis of the cracked linear viscoelastic solids. Numerical results of example problems show the accuracy and effectiveness of the proposed method.

• Communications of the Korean Mathematical Society
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• v.14 no.2
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• pp.337-352
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• 1999

In this paper we find a geometric condition for the weaker principle of spatial averaging (PSA) for a class of polyhedral domains. Let \ulcorner be a polyhedron in R\ulcorner, n$\leq$3. If all dihedral angles of \ulcorner are submultiples of $\pi$, then there exists a parallelopiped \ulcorner generated by n linearily independent vectors {\ulcorner}\ulcorner in R\ulcorner containing \ulcorner so that solutions of $\Delta$u+λu=0 in \ulcorner with either the boundary condition u=0 or ∂u/∂n=0 are expressed by linear combinations of those of $\Delta$u+λn=0 in \ulcorner with periodic boundary condition. Moreover, if {\ulcorner}\ulcorner satisfies rational condition, we guarantee the weaker PSA for the domain \ulcorner.

• Macromolecular Research
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• v.11 no.3
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• pp.152-156
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• 2003

We investigated epitaxial relations of phase transitions between the lamellar (L), hexagonally perforated layers (HPL), and gyroid (G) morphologies in styrene-isoprene diblock copolymer (PSI) and polyisoprene (PI)/PSI blend using rheology and small angle X-ray scattering (SAXS) techniques. In HPLlongrightarrowG transitions, six spot patterns of G phase were observed in two-dimensitional SAXS pattern. On the other hand, in direct L-longrightarrowG transition without appearance of HPL phase, the polydomain patterns of G phase were observed. From present study, it was understood that direct LlongrightarrowG transition of blend may be suppressed by high-energy barrier of transition and mismatches in domain orientation between epitaxially related lattice planes.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.498-501
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• 1998

This paper deals with the design and evaluation of the robust controller for a synchronous generator excitation system to improve the steady state and transient stability. The nonlinear characteristics of the system is treated as model uncertainties, and then the robust control techniques are introduced into the power system stability design to take into account these uncertainties at the controller design stage. The performance of the designed controller is examined by extensive non-linear time domain simulation. It is shown that the performance of the robust controller is superior to that of the conventional PI controller.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.3
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• pp.140-151
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• 2004

This paper presents the HVDC system modelling for analysis of subsynchronous oscillation and the design of the subsynchronous oscillation damping controller in HVDC system with the aid of novel eigenvalue analysis program. The HVDC system models include both the steady-state model for power flow calculation and the dynamic model for constructing the state matrix. The design procedures of the subsynchronous oscillation damping controller (SODC), which is integrated with PI controller at rectifier, consist of three steps:1) to identify the dominant torsional oscillation mode in the AC/DC system;2) to determine the parameters of the SODC for compensating the phase lagging due to the rectifier controller;3) to validate the control parameters and to determine the appropriate gain using a time-domain simulation program. The proposed design method has been tested against two AC/DC systems for validation.

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.6
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• pp.41-50
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• 2012

This paper presents a new sequence alignment method using the divide approach, which solves the problem by decomposing sequence alignment into several sub-alignments with respect to exact matching subsequences. Exact matching subsequences in the proposed method are bounded on the generalized suffix tree of two sequences, such as protein domain length more than 7 and less than 7. Experiment results show that protein sequence pairs chosen in PFAM database can be aligned using this method. In addition, this method reduces the time about 15% and space of the conventional dynamic programming approach. And the sequences were classified with 94% of accuracy.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1588-1590
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• 1997

The viewing angle characteristics of amorphous(a)-twisted nematic(TN)-liquid crystal display (LCD) on poly(vinyl)cinnamate (PVC) surfaces with photo polymerrization were investigated. It was found that the threshold voltage increases with increasing the polymerization of PVC surfaces. That the domain size of a-TN-LCD is affected by the surface crystallization with increasing the photo polymerization of the photo-alignment film. We observed that the viewing angle of a-TN-LCD increased with increasing the photo polymerization on PVC surfaces. Finally, we consider that the viewing angle of a-TN-LCD on PVC surfaces is large compared to a-TN-LCD on polyimide(PI) surface.

• Proceedings of the Acoustical Society of Korea Conference
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• 1996.06a
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• pp.9-12
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• 1996

This paper introduces an analysis of the non-axisymmetric mode due to in-plane vibration of an annular type piezoelectric actuator using FEM(Finite Element Method). The actuator is used as stator of ultrasonec motor. The freqrency charecterisrics and non-axisymmetric mode of the annular piezoelectric acruator are considered at a steady-state condition. The non-axisymmetric mode is occured by two sinusodial voltage sources with $\pi$/2 phase difference on the time domain. The resonant frequency of non-axisymmetric of non-axisymmetric mode is 60.358 kHz and 59.880 kHz for calculation and measurement, respectivly. The error was 0.8% between calculation and measurement. The revolution of the non-axisymmetric mode for actuator is analized at a period of exciting voltage sources using annimation. It is confirmed that the actuator has an usefulness as the stator of ultrasonic motor and the preposed method has a properity.

• Journal of the Korean Ceramic Society
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• v.23 no.4
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• pp.47-54
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• 1986

Since the wall mobility of bubble magnetic materials havin g the large q (q=Kac/2$\pi$$M_s^2$) like a $YFeO_3$ has been found to be proportional to the wall energy theoretically crystallographical direction dependence of wall energy calculated by the basis on the spin configuration of the bubble wall which lies in the ac plane was compared with the crystallographical direction dependence of wall mobility which was measured by the experiment. The sample was a single crystal of $YFeO_3$ which was cut into plate normal to the C axis and polished t a thickness of about 60${\mu}{\textrm}{m}$ The measurement of the wall mobility was carried out by optical system using the magneto-optic Faraday effect. From the good agreement of the crystallographical direction dependence of wall mobility and will energy it was found that the spin configuration of the bubble wall suggested is fair.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.545-548
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• 1999

The electro-optical characteristics of photo-aligned vertical-alignment (VA)-liquid crystal display (LCD) with non-polarized ultraviolet (UV) light irradiation of 45\`on homeotropic polyimide (Pl) surface were investigated. LC alignment on photo-aligned VA-LCD is attributed to photo-depolymerized reaction of the polymer with non-polarized UV light irradiation on PI surface. We had good voltage-transmittance (V-T) characteristics of photo-aligned VA-LCD. The response time of photo-aligned VA-LCD was slower than that of the rubbing-aligned VA-LCD. Finally, we suggest that the slow response time of photo-aligned VA-LCD depends on the LC domain.