• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1876-1878
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• 2004

A systematic approach of measurement, modeling and analysis of grounding system impedance is presented. The measurement and analysis system of ground impedance is based on a computer aided technique. The ground impedances of the ground rod are considerably dependent on the frequency. The ground impedance is mainly resistive in the frequency range of 3-20 kHz. At higher frequencies, the reactive components of the ground impedances are no longer negligible and the inductance of the ground rod was found to be the core factor deciding the ground impedance. As a consequence, the equivalent circuit model based on the measured data was proposed, and the calculated results were in approximately agreement with the measured data.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.73-76
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• 1996

An impedance control approach based on an extended task space formulation is addressed to control the kinematically redundant manipulators. Defining a weighted inner product in joint space, a minimal parametrization of the null space can be achieved and we can visualize the null space motion explicitly. Based on this formulation, we propose a control method called inertially decoupled impedance controller to control the motion of the end-effector as well as the internal motion expanding the conventional impedance control. Some numerical simulations are given to demonstrate the performance of the proposed control method.

• 비파괴검사학회지
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• 제27권3호
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• pp.217-223
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• 2007

This paper introduces an active sensing node using radio-frequency (RF) telemetry. This device has brought the traditional impedance-based structural health monitoring (SHM) technique to a new paradigm. The RF active sensing node consists of a miniaturized impedance measuring device (AD5933), a microcontroller (ATmega128L), and a radio frequency (RF) transmitter (XBee). A macro-fiber composite (MFC) patch interrogates a host structure by using a self-sensing technique of the miniaturized impedance measuring device. All the process including structural interrogation, data acquisition, signal processing, and damage diagnostic is being performed at the sensor location by the microcontroller. The RF transmitter is used to communicate the current status of the host structure. The feasibility of the proposed SHM strategy is verified through an experimental study inspecting loose bolts in a bolt-jointed aluminum structure.

• 한국전자파학회논문지
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• 제15권12호
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• pp.1147-1151
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• 2004

본 논문에서는 직사각형 전원평면에 대한 새로운 해석적 모델과 그에 기반한 임피던스 표현식을 제시하였다. 제안된 방법에서는 전원평면 구조를 그 둘레에 적당한 경계 조건을 가지는 일정 길이의 직사각형 도파관으로 모델화 하였다. 그 결과 제안된 모델에 기반하여 유도된 임피던스 표현식이 1차원 급수형태로 나타나며, 이는 기존에 제안된 전원평면의 구형 공동 모델에 기반한 임피던스 식에 비해 계산 효율을 크게 높일 수 있다.

• 대한기계학회논문집A
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• 제21권2호
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• pp.252-260
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• 1997

In this paper, a friction compensation method using a disturbance observer is proposed for an impedance control of pneumatic manipulator. It is assumed that the generated torque by a pneumatic actuator can be estimated based on the pressure signals and the discharge volume. In order to improve the dynamic characteristics of the pneumatic actuator driven by meter out method, we construct the inner torque control system by feeding back the generated torque. In order to reduce the influence of disturbances comprising friction torque and parameter variations of plant, the impedance control system is constructed with a disturbance observer which estimates the disturbances based on the generated torque of pneumatic actuator, the angular velocity and the reaction torque. From some experiments, it is confirmed that the proposed control system is effective to improve the robustness for the friction torque in the impedance control of a pneumatic manipulator.

• Smart Structures and Systems
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• 제17권6호
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• pp.881-901
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• 2016

In this study, a method to compensate the effect of temperature variation on impedance responses which are used for prestress-loss monitoring in prestressed concrete (PSC) girders is presented. Firstly, an impedance-based technique using a mountable lead-zirconate-titanate (PZT) interface is presented for prestress-loss monitoring in the local tendon-anchorage member. Secondly, a cross-correlation-based algorithm to compensate the effect of temperature variation in the impedance signatures is outlined. Thirdly, lab-scale experiments are performed on a PSC girder instrumented with a mountable PZT interface at the tendon-anchorage. A series of temperature variation and prestress-loss events are simulated for the lab-scale PSC girder. Finally, the feasibility of the proposed method is experimentally verified for prestress-loss monitoring in the PSC girder under temperature-varying conditions and prestress-loss events.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 추계학술대회 논문집 학회본부
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• pp.405-407
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• 1994

In order to provide reliable power service and to prevent a potentail hazard and damage, it is important to detect high impedance fault in power distribution line. This paper presents a neural network based approach for the detection of high impedance faults. A time delay neural network has been selected and trained for the fault currents obtained from field experiments. Detection experiments have been performed with the data from four different high impedance surfaces. Experimental results indicated the feasibility of using TDNN for the detection of high impedance faults.

• 전기학회논문지
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• 제61권3호
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• pp.373-379
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• 2012

This paper presents a fault location algorithm based on the adaptively estimated value of the local sequence source impedance for faults on a parallel transmission line. This algorithm uses only the local voltage and current signals of a faulted circuit. The remote current signals and the zero-sequence current of the healthy adjacent circuit are calculated by using the current distribution factors together with the local terminal currents of the faulted circuit. The current distribution factors consist of local equivalent source impedance and the others such as fault distance, line impedance and remote equivalent source impedance. It means that the values of the current distribution factors can change according to the operation condition of a power system. Consequently, the accuracy of the fault location algorithm is affected by the two values of equivalent source impedances, one is local source impedance and the other is remote source impedance. Nevertheless, only the local equivalent impedance can be estimated in this paper. A series of test results using EMTP simulation data show the effectiveness of the proposed algorithm. The proposed algorithm is valid for a double-circuit transmission line system where the equivalent source impedance changes continuously.

• 대한임베디드공학회논문지
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• 제14권5호
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• pp.259-267
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• 2019

This paper proposes a structure of a variable impedance control system based on sensor-less external force estimator of industrial manipulators for cyber physical production systems (CPPS). To implement CPPS, a feedback system is constructed by using the robot operating system (ROS) and an external force estimator which is designed to measure the external force applied to the manipulator without a force sensor. Based on the robot dynamics, the robot-human cooperating system for the cyber physics production system is implemented through a controller that changes the impedance characteristics of the manipulator according to the situation using the external force estimator. Simulation and experimental results verify the effectiveness of the proposed control system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1812-1815
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• 1997

This paper treats the estimation of human impedance and their application to collaboration work robot. Initially, we performa an experiment at whcich teh human becomes a slave and the robot behaves like a master having F/T sensor on its end. the human impedance expressed interms of mass, damping, and stiffness properties are estimated based on the force data measured by F/T sensor and the positiion data of the robot. To show the effectiveness of the estimated human impedance, we perform the second experiment at which the roles of the human and the robot are reversed. It is shown that the robot using the estimated human impedance follows the trajectory commanded by human very smoothly.