• 한국가스학회지
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• 제6권1호
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• pp.52-58
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• 2002

가스 배관 진단 시스템은 배관 내부에 투입되어 배관 내부의 여러 정보를 수집한다. 배관 진단을 위한 센서로는 배관 내부의 상태를 측정하는 캘리퍼(caliper) 센서와 온도, 압력센서가 있다. 그리고 정확한 위치 정보를 제공할 수 있는 IMU(Inertial Measurement Unit)와 주행 거리계를 사용하는 결합 항법 시스템도 필요하다. 본 논문에서는 가스 배관 진단시스템을 위한 항법 데이터 저장 시스템을 개발한다. 항법 데이터 저장 시스템은 실시간 동작을 위하여 마스터/슬레이브 구조를 가진다. 마스터 시스템은 항법 데이터를 저장하거나 통신하는데 사용하며 슬레이브 시스템은 센서 데이터를 처리한다. 개발된 항법 데이터 저장 시스템의 성능은 Pull Rig 실험을 통하여 검증한다.

• 센서학회지
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• 제25권5호
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• pp.377-381
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• 2016

NDIR $CO_2$ gas sensor was prototyped with ASIC implemented thermopile sensor which included temperature sensor and White-Cell structure in this paper. The temperature dependency of dual infrared sensors ($CO_2$ and reference IR sensors) has been characterized and their output voltage ratios according to the temperature and gas concentration were presented in this paper for achieving temperature compensation algorithm. The initial output voltages of NDIR $CO_2$ gas and reference IR sensors showed $3^{rd}$ order polynomial and linear output voltages according to the variation of ambient temperatures from 253 K to 333 K, respectively. The output voltages of temperature sensor presented a linear dependency according to the ambient temperature and could be described with V(T) = -3.0069+0.0145T(V). The characteristics of output voltage ratios could be modeled with five parameters which are dependent upon the ambient temperatures and gas concentration. The estimated $CO_2$ concentrations showed relatively high error below 300 ppm (maximum 572 % at 7 ppm $CO_2$ concentration), however, as the concentration increased from 500 ppm to 2,000 ppm, the overall estimated errors of $CO_2$ concentrations were less than ${\pm}10%$ in this research.

• 한국재료학회지
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• 제29권8호
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• pp.469-476
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• 2019

A lead-free bulk ceramic having a chemical formula $Ba_{0.8}Ca_{0.2}(Ti_{0.8}Zr_{0.1}Ce_{0.1})O_3$ (further termed as BCTZCO) is synthesized using mixed oxide route. The structural, dielectric, impedance, and conductivity properties, as well as the modulus of the synthesized sample are discussed in the present work. Analysis of X-ray diffraction data obtained at room temperature reveals the existence of some impurity phases. The natural surface morphology shows close packing of grains with few voids. Attempts have been made to study the (a) effect of microstructures containing grains, grain boundaries, and electrodes on impedance and capacitive characteristics, (b) relationship between properties and crystal structure, and (c) nature of the relaxation mechanism of the prepared samples. The relationship between the structure and physical properties is established. The frequency and temperature dependence of the dielectric properties reveal that this complex system has a high dielectric constant and low tangent loss. An analysis of impedance and related parameters illuminates the contributions of grains. The activation energy is determined for only the high temperature region in the temperature dependent AC conductivity graph. Deviation from the Debye behavior is seen in the Nyquist plot at different temperatures. The relaxation mechanism and the electrical transport properties in the sample are investigated with the help of various spectroscopic (i.e., dielectric, modulus, and impedance) techniques. This lead free sample will serve as a base for device engineering.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1168-1172
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• 2004

This paper presents a speed controller based on an adaptive fuzzy algorithm for high performance permanent magnet synchronous motor (PMSM) drives under parameter and load variations. In many speed tracking control systems PI controller has been used due to its simple structure and easy of design. PI controller, however, suffers from the electrical machine parameter variations and disturbances. In order to improve the tracking control performance under load variations, the PI controller parameters are modified during operation by adaptive fuzzy method. This method based on optimal fuzzy logic system has simple structure and computational simplicity. It needs only sample data which is obtained by optimal controller off-line. As the sample data implemented in the adaptive fuzzy system can be modified or extended, a flexible control system can be obtained. Simulation results show the usefulness of the proposed controller.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국제학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.406-411
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• 1993

A variable structure control scheme that can be applied to the process with input/output delays are proposed and its control performances are evaluated. The proposed VSCS, which is an output fedback scheme, comprises an integrator for tracking the setpoint and the Smith predictor for compensating the effects of time delay. With The VSCS, the robustness against the parameter variations and external disturbances can be achieved even when the controlled process includes I/O delays. And the desired transient response is obtained by simple adjustment of the coefficients of the switching surface equation.

• Nuclear Engineering and Technology
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• 제29권2호
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• pp.148-157
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• 1997

A new capsule that has a unique structure in which the test environments including neutron flux and fluence, and irradiation temperature can be controlled precisely during irradiation, was conceptually designed. The capsule structure and instrumentation were successfully designed according to the JMTR's standard procedures of capsule design. Based on the target irradiation, the details of the irradiation such as neutron fluence and irradiation temperature ore calculated and the related capsule safety was evaluated. In addition, the effects of design parameters including the changes in inner-capsule configuration, heater capacity, and Helium gas pressure on the specimen temperature were analyzed with a computer program. Through these thermal and strength evaluations, this capsule was proved to be safe during the irradiation in the JMTR.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1716-1722
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• 2005

Fuzzy logic, neural network, fuzzy-neural network play an important as the key technology of linguistic modeling for intelligent control and decision in complex systems. The fuzzy-neural network (FNN) learning represents one of the most effective algorithms to build such linguistic models. This paper proposes bacteria foraging algorithm based optimal learning fuzzy-neural network (BA-FNN). The proposed learning scheme is the fuzzy-neural network structure which can handle linguistic knowledge as tuning membership function of fuzzy logic by bacteria foraging algorithm. The learning algorithm of the BA-FNN is composed of two phases. The first phase is to find the initial membership functions of the fuzzy neural network model. In the second phase, bacteria foraging algorithm is used for tuning of membership functions of the proposed model.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.261-263
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• 1995

The continuous sliding mode controller with disturbance observer for the tracking control of permanent magnet synchronous motor(PMSM) is presented. In spite of the robust performance of variable structure control, there exists an undesirable chattering problem, which may be very harmful in some cases. To alleviate the problem, continuous sliding mode controller with continuous saturation function is proposed and also the prescribed performance can be obtained by efficient compensation of disturbance. Experimental results using 7.5 kW, 4000 rpm motor which is controlled by TMS320C30 DSP, are shown to demonstrate the usefulness of the proposed algorithm.

• Journal of Electrical Engineering and Technology
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• 제8권1호
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• pp.130-136
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• 2013

This paper presents the magnetic equivalent circuit analysis of a double-excited, two-degree-of-freedom (DOF) motor. The double-excited, 2-DOF motor is a laminated structure, making it easy to manufacture and giving it simple operating principles. We explain the structure of the 2-DOF motor and analyze the static characteristics using a magnetic equivalent circuit (MEC) to reduce analysis time. The feasibility of MEC analysis was confirmed by experimental results of the tilting, panning motion. We also confirmed the occurrence of holding torque in every motion.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.404-409
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• 1998

In this paper, the discrete variable structure controller (DVSC) is proposed for vector controlled induction motor position control. The variable structure control (VSC) which guarantees accuracy and robustness in nonlinear control system is developed in discrete time domain for applying to real servo system. Furthermore, the load torque observer is introduced to reduce chattering problem. The computer simulation results are presented to verify the proposed control scheme.