• ETRI Journal
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• 제42권4호
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• pp.534-548
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• 2020

This study presents a new architecture for a field programmable analog array (FPAA) for use in low-frequency applications, and a generalized circuit realization method for the implementation of nth-order elliptic filters. The proposed designs of both the FPAA and elliptic filters are based on the operational transconductance amplifier (OTA) used in implementing OTA-C filters for biopotential signal processing. The proposed FPAA architecture has a flexible, expandable structure with direct connections between configurable analog blocks (CABs) that eliminates the use of switches. The generalized elliptic filter circuit realization provides a simplified, direct synthetic method for an OTA-C symmetric balanced structure for even/odd-nth-order low-pass filters (LPFs) and notch filters with minimum number of components, using grounded capacitors. The filters are mapped on the FPAA, and both architectures are validated with simulations in LTspice using 90-nm complementary metal-oxide semiconductor (CMOS) technology. Both proposed FPAA and filters generalized synthetic method achieve simple, flexible, low-power designs for implementation of biopotential signal processing systems.

• 대한기계학회논문집
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• 제17권12호
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• pp.2982-2994
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• 1993

Low-velocity impact responses of composite laminates are investigated using the finite element method based on various theories. In two-dimensional nonlinear analysis, a displacement field considering higher order shear deformation and large deflection of the laminate is assumed and a finite element formulation is developed using a C$^{o}$-continuous 9-node plate element. Also, three-dimensional linear analysis based on the infinitesimal strain-displacement assumptions is performed using 8-node brick elements with incompatible modes. A modified Hertzian contact law is incorporated into the finite element program to evaluate the impact force. In the time integration, the Newmark constant acceleration algorithm is used in conjuction with successive iterations within each time step. Numerical results from static analysis as well as the impact response analysis are presented including impact force histories, deflections, strains in the laminate. Impact responses according to two typical low-velocity impact conditions are compared each other.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1449-1455
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• 2017

The vector control technique using low-resolution Hall-effect sensors has been widely used especially in consumer electronics. Due to electrical and/or mechanical unevenness related to binary-type Hall sensors, the calculated or estimated position information has discontinuities so called bumps, which causes the deterioration of vector control performance. In order to obtain a linearly changing position signal from low-precision Hall-effect sensors, this paper proposes a simple bumps in position signal removal algorithm that consists of a first-order observer with low-pass filtering scheme. The proposed algorithm has the feature of no needs for system parameters and additional estimation processes. The validity of the proposed method is verified through simulation and experimental results.

• 한국산학기술학회논문지
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• 제7권4호
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• pp.575-579
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• 2006

본 논문에서는 전동기 시스템의 극저속 영역에서 안정적이고 동특성이 우수한 운전을 하기 위해 전차원상태 관측기로부터 추정되는 속도정보를 입력으로 하는 최소차원 토크 관성관측기를 구성하여 부하외란과 관성을 피드포워드 제어를 함으로써 극저속영역에 대한 강인성을 갖도록 한다. 제시한 제어 알고리즘을 MATLAB SIMULINK를 통해 전체 시스템을 모델링하고 실험을 통해 극저속에서 속도 추정 능력이 향상됨을 확인 한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.234-236
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• 2005

In this paper, an instantaneous speed observer with a reduced order is proposed to implement an indirect control for an motor with excellent dynamic stability and performance in a very low speed region. The proposed observer can estimate the instantaneous speed in very low speed region and simplify the system configuration by adopting a least order load torque-inertia observer to estimate the load torque and the rotor speed. Simulation are carried out to illustrate the performance of the proposed estimator at very low speed.

• 한국건축시공학회지
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• 제21권2호
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• pp.149-156
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• 2021

본 연구는 도급공사의 공격적인 저가 수주로 인한 공사비 부족을 만회하기 위해 설계변경 등 자구책이 뒤따르게 되고, 이러한 과정에서 시공상의 하자가 유발될 수 있다는 점에 대하여 재무적 자료를 이용하여 실증분석하는 것을 목적으로 한다. 연구 결과, 공격적인 수주행위로 인한 수주량의 비상적인 증가와 영업이익률 등 수익성 악화는 공사 품질의 저하와 하자 발생으로 이어진다는 것을 확인하였다. 또한 시공눙력이 낮거나 공사 착공 후 설계나 계약 조건을 변경하는 경우 하자발생의 직접적인 원인이 된다는 것도 확인하였다. 공격적인 저가 수주와 하자 발생 사이의 관련성을 확인함으로써, 하자발생을 방지할 수 있는 방안을 마련하는 계기가 될 수 있다.

• Nuclear Engineering and Technology
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• 제49권6호
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• pp.1114-1124
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• 2017

Acceleration/preconditioning strategies available in the SCEPTRE radiation transport code are described. A flexible transport synthetic acceleration (TSA) algorithm that uses a low-order discrete-ordinates ($S_N$) or spherical-harmonics ($P_N$) solve to accelerate convergence of a high-order $S_N$ source-iteration (SI) solve is described. Convergence of the low-order solves can be further accelerated by applying off-the-shelf incomplete-factorization or algebraic-multigrid methods. Also available is an algorithm that uses a generalized minimum residual (GMRES) iterative method rather than SI for convergence, using a parallel sweep-based solver to build up a Krylov subspace. TSA has been applied as a preconditioner to accelerate the convergence of the GMRES iterations. The methods are applied to several problems involving electron transport and problems with artificial cross sections with large scattering ratios. These methods were compared and evaluated by considering material discontinuities and scattering anisotropy. Observed accelerations obtained are highly problem dependent, but speedup factors around 10 have been observed in typical applications.

• 충청수학회지
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• 제9권1호
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• pp.27-60
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• 1996

We compute low order terms of automorphisms of a quadric CR manifold defined by $v^a$ =< $A^az$, z > where there is a real vector ${\kappa}{\in}R^m$ such that $det({\kappa}{\cdot}A){\neq}0$.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 II
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• pp.1157-1160
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• 2003

We proposed a study on optimal clock period selection algorithm for low power RTL design. The proposed algorithm use the way of maintaining the throughput by reducing supply voltage after improve the system performance in order to minimize the power consumption. In this paper, it select the low power to use pipeline in the transformation of architecture. Also, the algorithm is important the clock period selection in order to maximize the resource sharing. however, it execute the optimal clock period selection algorithm.

• 대한전기학회논문지
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• 제36권2호
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• pp.140-147
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• 1987

In this paper, seven-order elliptic low-pass passive network is synthesized by using doublyterminated ladder network is directly transformed into the active network which has the advantage of low sensitivity and can be realized conveniently. The circuit simulation results of passive network and active network synthesized with FDNR and Leap-frog technique are compared, and it is proved that the two rest work has the same characteristics.