• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.310-313
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• 2003

This paper is proposed new fuzzy controller for high performance of interior permanent magnet synchronous motor (IPMSM) drive New fuzzy controller take out appropriate amounts of accumulated control input according to fuzzy described situations in addition to the incremental control input calculated by conventional direct fuzzy controller. The structures of the proposed controller is motivated by the problems of direct fuzzy controller. The direct controller generally give inevitable overshoot when one tries to reduce rise time of response especially when a system of order higher than one is under consideration. The undesirable characteristics of the direct fuzzy controller are caused by integrating operation of the controller, even though the integrator itself is introduced to overcome steady state error in response. Proposed controller fuzzy clear out integrated quantities according to situation. This paper attempts to provide a thorough comparative insight into the behavior of IPMSM drive with direct and new fuzzy speed controller. The validity of the comparative results is confirmed by simulation results for IPMSM drive system.

• 정보처리학회논문지A
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• 제15A권3호
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• pp.135-140
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• 2008

본 논문은 중복 다치논리(redundant multi-valued logic)를 이용하여 초고속 디멀티플렉서(demultiplexer)를 CMOS 회로로 설계하였다. 설계한 회로는 중복 다치논리를 이용하여 직렬 이진 데이터를 병렬 다치 데이터로 변환하고 이를 다시 병렬 이진 데이터로 변환한다. 중복 다치논리는 중복된 다치 데이터 변환으로써 기존 방식 보다 더 높은 동작속도를 얻을 수 있다. 구현한 디멀티플렉서는 8개의 적분기로 구성되어 있으며, 각 적분기는 누적기, 비교기, 디코더, D 플립플롭으로 구성된다. 설계한 회로는 0.18um 표준 CMOS 공정으로 구현하였으며 HSPICE 시뮬레이션을 통해 검증하였다. 본 논문의 디멀티플렉서의 최대 데이터 전송률은 20 Gb/s이고 평균 전력소모는 58.5 mW이다.

• 광학세계
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• 통권158호
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• pp.52-54
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• 2015

최근 무인항공기를 지칭하는 드론 관련 산업이 미래를 이끌 신산업으로 부상하고 있다. 드론은 20세기 초에 군사용으로 개발되어 정찰 감시 및 폭격과 같은 군사임무를 수행하여 왔으나 최근 들어 독일 DHL, 아마존, 구글 등과 같은 다국적 기업들이 상업적 용도로 활용을 선언하며 연구 개발에 뛰어 들면서 그 시장이 예상보다 빨리 커지고 있다. 미국 틸 그룹의 보고서에 의하면 2013년 세계 드론 시장의 규모는 66억 달러였고 그 중 군사용이 90% 이상을 차지하고 있으나 향후 민수용 시장 비율이 상당히 커질 것으로 예상된다. 2022년에는 114억 달러 규모로 커질 것으로 예상하고 있다. 현재 민수용으로 사진 촬영용 소형 드론으로부터 정밀농업, 인프라 관리, 택배 및 화물 수송 등으로 운용 범위를 확대하고 있다. 국내 드론 산업은 군수 위주로 시작되어 세계 7위권의 기술력을 확보한 것으로 평가되고 있다. 무인기 분야의 연구개발은 국방과학연구소와 한국항공우주연구원 등 정부출연연구소가 주도하는 가운데, 한국항공우주산업, 대한 항공이 주로 체계종합(System Integrator) 및 비행체 개발을 담당하고 LIG넥스원, 삼성탈레스, 삼성테크윈 등의 대기업을 포함한 중소업체들이 부체계 기술을 개발하고 있다. 최근 소형 드론을 중심으로 시장형성이 가시화되는 민수 시장에서는 가격, 기술 경쟁력의 열위에 있어, 국내 산업 경쟁력 확보와 미래 시장을 선도할 핵심 제품 개발이 시급한 실정이다. 또한 무인기의 비행체 국산화는 상당한 수준으로 진행되었으나, 광학(EO) 적외선(IR) 카메라 등 핵심 부가가치를 구성하는 탑재 임무장비의 경우 원천기술의 부족으로 해외에 의존하고 있다.

• Progress in Superconductivity
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• 제5권1호
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• pp.31-37
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• 2003

Wide-bandwidth SQUID current amplifier and its control electronics have been constructed for detecting pulse outputs of a superconducting microcalorimeter. The current amplifier made of a double relaxation oscillation SQUID (DROS) has a bandwidth of 1.2 MHz and typical white noise level of about 6 pA/(equation omitted) Hz. To increase the dynamic range of the current amplifier, the flux-locked loop (FLL) has additional circuits to reset the integrator and to count reset numbers which present the number of passed flux quanta. In this system, dynamic range covers from -65 mA to +65 mA. SQUID electronics are controlled by software to get the optimum FLL condition, and to control the current to bias the transition edge sensor (TES). The electronics are shielded from the outside electromagnetic noises by using an aluminum case of 66 mm ${\times}$ 25 mm ${\times}$ 100 mm, and consist of 2 separate printed-circuit-boards for the current amplifier and the control electronics, respectively. The SQUID current amplifier and its control electronics will be used in TESs for detecting photons such as UV and X-ray with high energy resolution.

• Advances in aircraft and spacecraft science
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• 제5권6호
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• pp.653-669
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• 2018

This work has the objective to analyze multibody mechanisms of inflatable structures for manned space applications. The focus is on the evaluation of the main characteristics of MaxFlex, a new module of MSC Adams including the effect of nonlinear flexible bodies. MaxFlex integrates the nonlinear Finite Element Analysis (FEA) of Nastran-SOL400-and the Adams multibody capabilities in one unique solver, providing an improvement concerning the concept and technology based on the co-simulation among solvers. MaxFlex converts the equations of motion of the nonlinear FEA into phase-space form and discretizes them according to the multibody system integrator framework. The numerical results deal with an inflatable manned space module having rigid components and a flexible coating made of Kevlar. This paper is a preliminary assessment of the computational capabilities of the software and does not provide realistic guidelines for the actual design of the structure. The analysis leads to some recommendations related to the main issues to consider in a nonlinear simulation including both rigid and flexible components. The results underline the importance of realistic deployment times and applied forces. Also, a proper structural modeling is necessary, but can lead to excessive computational overheads.

• Structural Engineering and Mechanics
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• 제1권1호
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• pp.87-102
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• 1993

A $C^{\circ}$ continuous finite element formulation of a higher order displacement theory is presented for predicting linear and geometrically non-linear in the sense of von Karman transient responses of composite and sandwich plates. The displacement model accounts for non-linear cubic variation of tangential displacement components through the thickness of the laminate and the theory requires no shear correction coefficients. In the time domain, the explicit central difference integrator is used in conjunction with the special mass matrix diagonalization scheme which conserves the total mass of the element and included effects due to rotary inertia terms. The parametric effects of the time step, finite element mesh, lamination scheme and orthotropy on the linear and geometrically non-linear responses are investigated. Numerical results for central transverse deflection, stresses and stress resultants are presented for square/rectangular composite and sandwich plates under various boundary conditions and loadings and these are compared with the results from other sources. Some new results are also tabulated for future reference.

• Structural Engineering and Mechanics
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• 제32권4호
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• pp.501-516
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• 2009

This paper aims to study the large deflections of variable-arc-length elastica subjected to the terminal forces (e.g., axial force and torque). Based on Kirchhoff's rod theory and with help of Euler parameters, the set of nonlinear governing differential equations which free from the effect of singularity are established together with boundary conditions. The system of nonlinear differential equations is solved by using the shooting method with high accuracy integrator, seventh-eighth order Runge-Kutta with adaptive step-size scheme. The error norm of end conditions is minimized within the prescribed tolerance ($10^{-5}$). The behavior of VAL elastica is studied by two processes. One is obtained by applying slackening first. After that keeping the slackening as a constant and then the twist angle is varied in subsequent order. The other process is performed by reversing the sequence of loading in the first process. The results are interpreted by observing the load-deflection diagram and the stability properties are predicted via fold rule. From the results, there are many interesting aspects such as snap-through phenomenon, secondary bifurcation point, loop formation, equilibrium configurations and effect of variable-arc-length to behavior of elastica.

• 한국통신학회논문지
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• 제18권8호
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• pp.1159-1168
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• 1993

스윗치드-캐패시터 적분기(SCI)는 스욋치드-캐패시터 필터(SCF)를 구성하기 위한 기본 블럭이다. SCI에 사용된 op-amp의 유한이득과 유한대역폭으로 인하여 발생되는 오차때문에 많은 SCF가 사용에 제한을 받는다. 물론 능동 RC 필터를 위한 여러가지 보상법을 직접적으로 SCF에 적용시킬 수는 있지만, 이 방법은 필터 응답에 미치는 op-amp의 동특성에 대한 영향을 해석하는데는 적합치 않다. Op-amp의 유한이득에 의한 영향은 능동 RC필터와 유사하지만 유한 대역폭에 의한 영향은 SCF가 더욱 견실성이 있다. 본 논문에서는 SCI에 사용된 Op-amp의 유한 이득과 대역폭으로 인한 오차를 고찰하고 버퍼회로를 이용하여 이를 보상할 수 있는 간단하고 효과적 인 방법을 제시한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.388-390
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• 2006

This paper presents a hybrid SoC design for phase detection of single tone signal. The designed hybrid SoC is composed of three functional blocks, i.e., an analog to digital converter module, a phase detection module and a controller module. A design of the controller module is based on a 16-bit RISC architecture. An I/O interface and an LCD control interface for transmission and display of phase measurement values are included in the design of the controller module. A design of the phase detector is based on a recursive sliding-DFT. The recursive architecture effectively reduces the gate numbers required in the implementation of the module. The ADC module includes a single-bit second-order sigma-delta modulator and a digital decimation filter. The decimation filter is designed to give 98dB of SNR for the ADC. The effective resolution of the ADC is enhanced to 98dB of SNR by the incorporation of a pre FIR filter, a 2-stage cascaded integrator- comb(CIC) filter and a 30-tab FIR filter in the decimation. The hybrid SoC is verified in FPGA and implemented in 0.35 CMOS Technology.

• International Journal of Control, Automation, and Systems
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• 제5권5호
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• pp.547-558
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• 2007

This paper proposes a simpler solution to the stabilization problem of a special class of nonlinear underactuated mechanical systems which includes widely studied benchmark systems like Inertia Wheel Pendulum, TORA and Acrobot. Complex internal dynamics and lack of exact feedback linearizibility of these systems makes design of control law a challenging task. Stabilization of these systems has been achieved using Energy Shaping and damping injection and Backstepping technique. Former results in hybrid or switching architectures that make stability analysis complicated whereas use of backstepping some times requires closed form explicit solutions of highly nonlinear equations resulting from partial feedback linearization. It also exhibits the phenomenon of explosions of terms resulting in a highly complicated control law. Exploiting recently introduced Dynamic Surface Control technique and using control Lyapunov function method, a novel nonlinear controller design is presented as a solution to these problems. The stability of the closed loop system is analyzed by exploiting its two-time scale nature and applying concepts from Singular Perturbation Theory. The design procedure is shown to be simpler and more intuitive than existing designs. Design has been applied to important benchmark systems belonging to the class demonstrating controller design simplicity. Advantages over conventional Energy Shaping and Backstepping controllers are analyzed theoretically and performance is verified using numerical simulations.