• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.325-326
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• 2006

In this study, in order to develop piezoelectric device for multilayer piezoelectric ultrasonic motor, low temperature sintering $Pb(Mn_{1/3}Nb_{2/3})_{0.02}(Ni_{1/3}Nb_{2/3})_{0.12}(Zr_{0.48}Ti_{0.52})_{0.86}O_3$ system ceramics were fabricated according to the variations of forming pressure of casting sheet. At the 300[$kgf/cm^2$] forming pressure, the maximum density of 7.8[$g/cm^3$] was obtained. At the 350[$kgf/cm^2$] forming pressure, the maximum values of effective electromechanical coupling factor $k_{cff}\;=\;0.24$ and mechanical quality factor Qm=628 were obtained.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.637-638
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• 2007

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.69-69
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• 2003

최근 trench capacitor, isolation trench, micro-electromechanical system(MEMS), micro-opto-electromechanical system(MOEMS)등의 다양한 기술에 적용될 고종횡비(HAR) 실리콘 식각기술연구가 진행되어 지고 있다. 이는 기존의 습식식각시 발생하는 결정방향에 따른 식각률의 차이에 관한 문제와 standard reactive ion etching(RIE) 에서의 낮은 종횡비와 식각률에 기인한 문제점들을 개선하기 위해 고밀도 플라즈마를 이용한 건식식각 장비를 사용하여 고종횡비(depth/width), 높은 식각률을 가지는 이방성 트랜치 구조를 얻는 것이다. 초기에는 주로 HBr chemistry를 이용한 연구가 진행되었는데 이는 식각률이 낮고 많은양의 식각부산물이 챔버와 시편에 재증착되는 문제가 발생하였다. 또한 SF6 chemistry의 사용을 통해 식각률의 향상은 가져왔지만 화학적 식각에 기인한 local bowing과 같은 이방성 식각의 문제점들로 인해 최근까지 CHF3, C2F6, C4F8, CF4등의 첨가가스를 이용하여 측벽에 Polymer layer의 식각보호막을 형성시켜 이방성 구조를 얻는 multi_step 공정이 일반화 되었다. 이에 본 연구에서는 SF6 chemistry와 소량의 02/HBr의 첨가가스를 이용한 single_step 공정을 통해 공정의 간소화 및 식각 프로파일을 개선하여 최적의 HAR 실리콘 식각공정 조건을 확보하고자 하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1994년도 추계학술대회 논문집
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• pp.3-7
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• 1994

In this study, to improve sintering condition, anisotropic Property(k$\_$t//k$\_$p/) of electromechanical coupling coefficients, and hydrostatic piezoelerlric constants d$\_$h/ and g$\_$h/, MnO$_2$impurity was added to the (Pb$\_$0.76/Ca$\_$0.24)[(Co$\_$$\frac{1}{2}$W$\_$$\frac{1}{2}$/)$\_$0.04/Ti$\_$0.96/]O$_3$ System ceramics for hydrophone. And the structural, electrical properties of them were investigated. As a results. tetragonality was decreased with MnO$_2$ additives and density was the highest value of 7.06(g/㎤) at H2-3 specimen. Electromechanical coupling coefficients of H2-3 specimen were k$\_$t/=49 and k$\_$p/ 0, which exibited the hightest hydrostatic piezoelectric constants of d$\_$h/=64.52[10$\^$-1/C/N] and g$\_$h/=35.92[10$\^$-3/ Vm/N].

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권2호
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• pp.140-148
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• 2000

In this paper, using surface micromachining technology with thick photoresist and aluminum, an SLM(Spatial Light Modulator), which is applied to the fields of adaptive optics and pattern recognition system, was fabricated and the electromechanical properties of the fabricated micro SLM are measured. In order to maximize fill-factor and remove mechanical coupling between micro SLM actuators, the micro SLM is composed of three aluminum layers so that spring structure and upper electrode are placed beneath the mirror plate, and $10\times10$ each mirror plate is individually actuated. Also, the micro SLM was designed to be able to modulate phase and amplitude of incoming light in order to have a continuity of phase modulation of incoming light. In the case of amplitude and phase modulation, maximum vertical displacement is 4$\mum$, and maximum angular displacement is $\pm4.6^{\corc}$ respectively. The height difference of the fabricated mirror plate was able to be reduced to 1100A with mirror plate planarization method using negative photoresist(AZ5214). The electromechanical properties of the fabricated micro SLM were measured with the optical measurement system using He-Ne laser and PSD(position sensitive device).

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.1117-1120
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• 1999

In this paper, we design the H$\infty$ optimal controller satisfying robust stability and performance in spite of the plant uncertainty for an electro-mechanical actuator system and analyze the controller in frequency domain. H$\infty$ optimal controller K was designed using iteration algorithm suggested by DOYLE. Using the controller in an electro-mechanical actuator system, the joint with very small coupling rigidity coefficient was used to vary the control parameter. The plant unstructured uncertainty was assumed to be a multiplicative type.

• Advances in aircraft and spacecraft science
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• 제3권2호
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• pp.211-224
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• 2016

The present study aims to investigate the shimmy stability behavior of a single wheeled nose landing gear system. The system is supposed to be equipped with an electromechanical actuator capable to control the shimmy vibrations. A Proportional-Integrative-Derivative (PID) controller, tuned by using the Particle Swarm Optimization (PSO) procedure, is here proposed to actively damp the shimmy vibration. Time-history results for some test cases are reported and commented. Stochastic analysis is last presented to assess the robustness of the control system.

• 한국전기전자재료학회논문지
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• 제20권2호
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• pp.124-129
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• 2007

Dielectric and piezoelectric properties of $0.57Pb(Sc_{1/2}Nb_{1/2})O_{3}-0.43PbTiO_{3}$, which is the morphotropic phase boundary composition for the PSN-PT system, were investigated as a function of $Fe_{2}O_{3},\;Nb_{2}O_{5}\;and\;MnO_{2}$ addition 0 wt% to 0.9 wt%. The maximum dielectric constant of ${\varepsilon}_{33}/{\varepsilon}_{o}=2054$ and the minimum dielectric loss of $tan{\delta}=0.37\;%$ at room temperature were obtained at 0.1 wt% of $Fe_{2}O_{3}$ and 0.5 wt% of $MnO_{2}$ addition, respectively. With addition of 0.5 wt% $Nb_{2}O_{5}$ and $0.5\;wt%\;MnO_{2}$, the electromechanical coupling factor $k_{p}$ and mecanical quality factor $Q_{m}$ were significantly increased, respectively. The maximum electromechanical coupling factor $k_{p}=61.5\;%$ was obtained by addition of $Nb_{2}O_{5}$ and high mechanical quality factor $Q_{m}=919$ was obtained by addition of $MnO_{2}$. The $Q_{m}(=919)$ value is 3.3 times larger than that of non-doped 0.57PSN-0.43PT ceramics.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.333-336
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• 1997

In this paper, we present a nonlinear dynamic controller for position tracking of brushless dc motors. In constructing the controller, a backstepping-type approach is used under the condition of full state information, while an adaptive controller is adopted for parameter uncertainty throughout the entire electromechanical system. The nonlinear dynamic controller using the adaptive learning technique approach is shown to drive the state variables of system to the desired ones asymptotically and whose effectiveness is also sown via computer simulation.

• 한국정밀공학회지
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• 제23권9호
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• pp.92-101
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• 2006

In this paper a adaptive backstepping control scheme is proposed for control of a do motor driving a one-link manipulator. Fuzzy logic systems are used to approximate the unknown nonlinear function including the parametric uncertainty and disturbance throughout the entire electromechanical system. A compensation controller is also proposed to estimate the bound of approximation error. Thus the asymptotic stability of the closed-loop control system can be obtained. Numerical simulations are included to show the effectiveness of the proposed controller.