Speed and tension control for continuous strip processing line

학위논문(박사)--서울대학교 대학원 :전기공학부,1999.Docto

A feasibility study on estimation of the deformation of rubber bush in vehicles using acceleration and displacement signals on the links

학위논문(석사) - 한국과학기술원 : 기계공학과, 2016.8 ,[ii, 74 p. :]자동차의 현가장치는 여러 링크 및 연결부의 고무 부시들로 구성된다. 승차감을 결정하는 차체의 진동특성은 고무 부시의 영향을 받는다. 차량 개발 단계에서, 주행 중 부시를 통한 전달력과 부시의 변형량을 알면 차체의 진동 특성을 예측하여 승차감을 개선안을 마련 가능하다. 최근 들어, 부시에서의 전달력은 링크에 힘 센서를 설치하여 측정되는 반면, 부시의 변형량 측정은 활발히 이루어지지 않고 있다. 본 연구에서는 압전형 가속도계 및 자기 유도형 변위계를 이용한 부시 변형량 추정 방법을 제안했으며, 실제 주행 상황에의 적용 가능성에 대해 논하였다. 링크의 강체 운동 가정 하에, 두 링크 간 상대 변위 측정 정보로부터 부시의 변형량을 추정하였다. 가속도계는 수 Hz부터 최대 수백 Hz까지의 고주파 영역, 변위계는 최대 수십 Hz의 저주파 영역의 링크 진동을 측정하는 데에 사용되었다. 실제 차량 주행 상황에 준하는 크기 수준의 부시 변형량을 발생시키고, 제안된 방법을 이용하여 변형량을 추정하였다. 기준 센서 이용 변형량 추정 결과에 대한 오차는 5% 미만으로, 주행 중 발생하는 수준의 변형량 추정이 가능함을 보였다.한국과학기술원 :기계공학과

A Study on Implementable Sun Tracking Algorithm for Mobile Systems

In this paper, a prototype of implementable Sun tracking algorithm for mobile systems powered by alternative energy is proposed. The proposed system uses 2-axis tilt sensor and 3-axis magnetic sensor to measure orientation and posture of the system according to the horizon coordinates system, which are used to compensate tilt effects. Then through astronomical calculation using the present time and position informations obtained from GPS sensors, the calculated azimuth and altitude of the Sun in that location. The position of the Sun is converted to that of the mobile Sun tracking system coordinates and used to control A-axis and C-axis of the system.1

셀룰러 망에서 용량과 공평성 증대를 위한 기회적인 릴레이 기법

학위논문(석사) - 한국과학기술원 : 전기및전자공학전공, 2006.2, [ vi, 50 p. ]In this paper, we study how the opportunistic relaying can improve both capacity and fairness in cellular network. In wireless network, capacity and fairness are two goals which cannot be achieved simultaneously. To maximize the cell throughput, fairness cannot be guaranteed and vice versa. We show that the achievable average throughput region can be enlarged by using the cooperative relaying. Thus, the enlarged region means that capacity and fairness can be improved at the same time with adequate scheduling algorithm. From the proposed scheduling algorithm, any fairness criterion can be achieved by adjusting control variable. The achieved throughput by opportunistic relaying shows that the max-min fairness does not sacrifice the cell capacity when the relaying channel gains are infinite. From the simulation, we show that the performance improvement gets higher as the user channels become more heterogeneous. Additionally, we propose the feedback algorithm to diminish the amount of the feedback.한국과학기술원 : 전기및전자공학전공

Efficiency analysis of the boost converter using power balance condition

Solararrayhasthefollowingnonlinearcharacteristic,suchaswhoseoutputcurrentincreases,outputvoltage isreduced.Forthisreason,boostconverterwith solararray system isalwayscontrolled to remain on the maximum powerpointofthesolararray.Inthiscase,wearenotfocusedontheoutputofthesolararrayand notconsiderefficiencyoftheboostconverter,whichisassumedreliable.Butefficiencyoftheconverteralsoshould beconsidered ,which affectsthetotalefficiency oftheoverallsolarenergy system.In thispaper,efficiency calculationoftheboostconverterusingpowerbalancemethodisproposed,whichwillbeusedforapowerful referencebeforehardwarerealization.2

The Design of Interleaved Bi-directional DC-DC Converter for Fuel Cell and Battery Hybrid System

Fuel cell power system is one of the most promising energy source for the alternative energy because it has unique advantages such as high energy density, no power drop during operation, and feasible to make compact size. However, due to very low response time, fuel cell is difficult to correspond to drastic load changes and start-up operation. For solving these problem, fuel cell power system must include energy storage device such as Li-Poly battery or super capacitor. Therefore, bi-directional DC-DC converter must be required for this storage device and fuel cell-PCS control. This paper presents a design and modeling of the bi-directional DC/DC converter. Firstly, we present modeling the boost and buck mode of the bi-directional converter through both PWM switch model and state space averaging technique. Secondly, in order to minimize output ripple and transient response overshoot, we have two identical DC-DC converters interleaved and adopt two-loop voltage-current controller. The proposed bi-directional DC-DC converter’s modeling method and control design have been verified with computer simulation and experimentation.FALS

Boost Converter Modeling of Photovoltaic Conditioning System for MPPT

Photovoltaic conditioning systems normally use a maximum power point tracking (MPPT) technique to deliver the highest possible power to the load continuously when variations occur in the insolation and temperature. A unique method of tracking the maximum power points (MPPs) and forcing the boost converter system to operate close to these points is presented through deriving small-signal model and transfer function of boost converter considering input capacitor. This paper aims at modeling boost converter including fairly large equivalent series resistance(ESR) of input reservoir capacitor by state-space-averaging method and PWM switch model and compares both methods using Bode plots. In the future, properly designed controller for compensation will be constructed in 3kw real system for maximum photovoltaic power tracking control.2

Loss analysis to the various kinds of core for PCS inductor and transformer

In recently,inductorand transformeris the common deviceusing widely in thephotovoltaic system and powerelectronics.Therefore,eachinductorandtransformerhasdifferentcorelossandironlossdependingon the size and kinds ofcore materials,itis importantto analyze loss characteristics forbettertransformer efficiency.This paper offers an efficiency calculation method for PCS inductor and transformer loss,and differentkindsofcorematerialsareanalyzedforoptimizedPCS design2

A Compensation of the Grid Current Unbalance and Distortion caused by the Grid Voltage Unbalance and Distortion in 3-Phase Bi-Directional DC to AC Inverter

This paper presents an algorithm of a compensation of the grid current distortion caused by the grid voltage unbalance and distortion in 3-phase bi-directional DC to AC inverter. Usually 3-phase grid system has unbalance and distortion because of connecting 1-phase and non-linear load with 3-phase load using same input node. Controlling 3-phase inverter by general method under the unbalanced and distorted grid voltage, the grid current has distortion. This distortion of the grid current cause the grid voltage distortion again. So, it need to control the grid current balanced and non-distorted, even the grid voltage gets unbalanced and distorted. There are some complex method to compensate the gird current distortion. it suggest simple method to solve the problem. Simulation and experiment is used to validate the proposed algorithm.2

The Design of Digital Controller for Boost Converter on Photovoltaic System

In photovoltaic system, the specifications of solar array is changed as open circuit voltage and short circuit current because of cell temperature and solar radiation. A boost converter of this system connects between output of photovoltaic system and DC link capacitor of grid connected inverter as controlling duty ratio. Therefore to supply stable voltage to the grid, a boost converter is need to keep certain voltage output. Considering the capacitance and the resistance of boost converter, this paper designed proper digital controller.2