• Journal of Information Display
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• 제6권4호
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• pp.11-15
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• 2005

We propose a current mode logic circuit design method for LTPS TFT for enhancing circuit operating speed. Current mode inverter/buffers with passive resistive load had been designed and fabricated. Measurement results indicated that the smaller logic swing of the current mode allowed significantly faster operation than the static CMOS. In order to reduce the chip size, both all pTFT and all nTFT active load current mode inverter/buffer had been designed and analyzed by HSPICE simulation. Even though the active load current mode circuits were inferior to the passive load circuits, it was superior to static CMOS gates.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.22.4-22
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• 2001

In this paper, the discrete optimal control is made to have the robust property of sliding mode controller. A augmented system with a virtual state is constructed for this objective and noble sliding surface is constructed based on this system. The sliding surface is the same as the optimal control trajectory in the original system. The states follow the optimal trajectory even if there exist uncertainties. The reaching phase problem of sliding mode control is desappear in this method.

• International Journal of Industrial Entomology and Biomaterials
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• 제27권2호
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• pp.322-325
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• 2013

In the present study, we report that the selection of operation mode is important to take the full advantage of nanofibrous membrane in enzyme immobilization. Silk fibroin nanofibrous membrane has been prepared by electrospinning, and a-chymotrypsin was immobilized as a model enzyme. When the immobilized enzyme was operated in the membrane reactor mode, the Michaelis constant, Km, was lower and the Vmax was higher compared to the batch reactor mode. No concentration gradient was observed in the membrane reactor mode and the immobilized enzyme was stable even after 7 times of re-use. Our results suggests that the enzyme immobilized nanofibrous membrane should be operated in the membrane reactor mode rather than in the bath reactor mode.

• Journal of Power Electronics
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• 제9권1호
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• pp.117-123
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• 2009

This paper presents a sliding mode observer for the sensorless control of interior permanent magnet synchronous motor (IPMSM) drives. The sliding mode observer has been presented as a robust estimation method. Most of these previous works, however, were not for an interior PMSM (IPMSM), but for a non-salient pole PMSM and its observer design is conducted in the stationary reference frame. Thus, in this paper, we investigate the design of a sliding mode observer and its driving characteristics for an IPMSM. The proposed sliding mode observer is designed in the rotating reference frame, and good drive performance is achieved even when the observer parameters are mismatched with those of an actual motor. The proposed method is applied to a 600W IPMSM, and, then, the measurement results are presented.

• 대한전자공학회논문지TC
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• 제47권8호
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• pp.61-67
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• 2010

일반적으로 MIS(도체-부도체-반도체)의 다층 구조로 이루어진 대칭 결합선로에 대한 해석 절차는 모드(even and odd) 해석에 기초한 특성임피던스와 전파상수를 추출함으로서 단층의 결합선로 해석 절차와 동일하다. 본 논문에서는 손실매질의 다층구조로 이루어진 마이크로 스트립선로의 손실특성의 개선을 위한 새로운 구조를 제안한다. MIS 구조로 된 전송선로의 Si와 SiO2층 사이에 0전위를 가진 도체를 일정한 간격의 주기적인 배열로 고안된 새로운 모델의 MIS구조에 대한 유한차분법을 이용한 해석방법이 사용된다. 특히 전송선로에 대한 유전체의 영향을 줄이기 위하여 0전위를 가진 주기적인 결합의 도체로 이루어진 구조가 시간영역의 신호를 통해 시험된다. 다양한 손실률을 가진 불완전 유전체에 따른 주파수 의존적인 추출된 전송선로 파라미터와 등가회로 파라미터가 주파수 함수로서 나타내진다. 특히 본 논문에서 제안한 새로운 구조의 불완전 유전체에 대한 전송선로 파라미터가 주파수 함수로 구해진다.

• Structural Engineering and Mechanics
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• 제73권3호
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• pp.271-286
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• 2020

Passive control technologies are commonly used in several areas to suppress structural vibrations by the addition of supplementary damping, and some modal damping may be heavy beyond critical damping even for regular structures with energy dissipation devices. The design of passive control structures is typically based on (complex) mode superposition approaches. However, the conventional mode superposition approach is predominantly applied to cases of under-critical damping. Moreover, when any modal damping ratio is equal or close to 1.0, the system becomes defective, i.e., a complete set of eigenvectors cannot be obtained such that some well-known algorithms for the quadratic eigenvalue problem are invalid. In this paper, a generalized complex mode superposition method that is suitable for under-critical, critical and over-critical damping is proposed and expressed in a unified form for structural displacement, velocity and acceleration responses. In the new method, the conventional algorithm for the eigenvalue problem is still valid, even though the system becomes defective due to critical modal damping. Based on the modal truncation error analysis, modal corrected methods for displacement and acceleration responses are developed to approximately consider the contribution of the truncated higher modes. Finally, the implementation of the proposed methods is presented through two numerical examples, and the effectiveness is investigated. The results also show that over-critically damped modes have a significant impact on structural responses. This study is a development of the original complex mode superposition method and can be applied well to dynamic analyses of non-classically damped systems.

• Journal of Power Electronics
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• 제5권1호
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• pp.20-28
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• 2005

This paper presents a fuzzy predictive sliding mode control for high performance induction motor position drives. A new simplified inner-loop sliding-mode current control scheme based on a nonlinear mathematical model of an induction motor is introduced. Novel predictive fuzzy logic PI and PID controllers are used in speed and position loops, respectively. Sliding-mode current controllers and fuzzy predictive logic controllers are designed based on indirect vector control. The overall system performance is examined under different dynamic operating conditions. The performance of the drive system is robust and stable, and insensitive to parameters and operating condition variations even though non-exact system parameters are used in the implementation of the proposed controllers.

• ETRI Journal
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• 제30권3호
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• pp.480-482
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• 2008

A novel InGaAsP/InP buried-ridge waveguide laser diode structure is proposed and demonstrated for use as a single-mode laser. The lateral mode of the proposed device can be controlled by adjusting the composition and thickness of the InGaAsP layer grown over the active region. Stable single-mode operation without kinks or beam-steering is achieved successfully with lateral and transverse in the junction plane even for the device with the ridge width of 9 ${\mu}m$ up to an injection current of 500 mA.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.853-861
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• 2007

To understand the concept of dynamic motion in two degree nonlinear coupled system, free vibration not including damping and excitation is investigated with the concept of nonlinear normal mode. Stability analysis of a coupled system is conducted, and the theoretical analysis performed for the bifurcation phenomenon in the system. Bifurcation point is estimated using harmonic balance method. When the bifurcation occurs, the saddle point is always found on Poincare's map. Nonlinear phenomenon result in amplitude modulation near the saddle point and the internal resonance in the system making continuous interchange of energy. If the bifurcation in the normal mode is local, the motion remains stable for a long time even when the total energy is increased in the system. On the other hand, if the bifurcation is global, the motion in the normal mode disappears into the chaos range as the range becomes gradually large.

• 한국세라믹학회지
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• 제35권7호
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• pp.671-678
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• 1998

Hertzian indentation tests with sphere indenters were used to study the mechanical properties of glass-in-filtrated alumina and spinel composites and evaluated the effect of preform microstructure and evaluated the effect of preform microstructure and glass con-tents on contanct damage and strength. The spinel composite showed more brittle behavior than the alumina composite which is verified from indentation stress-strain curve cone cracks and quasi-plastic deformation developed at subsurface. Failure originated from either cone cracks(brittle mode) or deformation zone(quasi-plastic mode) above critical load for cracking(Pc) and yield ({{{{ {P }_{Y } }}) with the brittle mode more dominant in the spinels and the quasi-plastic mode more dominant in the aluminas. Even though brittle mode was dominant in the spinel composites the strength degradation from accumulation of damage above these critical loads was conspicuously small suggesting that the glass-infiltrated composites should be highly damage tolerant to the blunt contacts.