• 제목/요약/키워드: Thermal compensation

검색결과 212건 처리시간 0.036초

페룰 가공용 고정밀 주축시스템 설계 (Design of High Precision Spindle System for Ferrule Grinding Machine)

  • 편영식;박정현;이건범;요꼬이요시유끼;여진욱
    • 한국정밀공학회:학술대회논문집
    • /
    • 한국정밀공학회 2002년도 춘계학술대회 논문집
    • /
    • pp.15-19
    • /
    • 2002
  • With the rapid development of industrial technologies, the demand for high precision products has been increasing drastically. For this reason, the need for developing of high performance machine tool, which can ensure high precision, is desired in the industrial fields. Technologies on the spindle system manufacture, guideway manufacture, error compensation, design of bed structure, protection against vibrations, and system integration are core technology for developing of high precision machine tools. Especially, among these, design of spindle system, which is leading precision and manufacturing technique. is one of the most important technologies. A high speed and high precision spindle system, which will be used for final machining of ferrule, is designed considering the effect caused by thermal, cutting torque, cutting farce, and work-piece materials. The detail process of analysis is presented.

  • PDF

REFOCUSING FOR ON-ORBIT MTF COMPENSATION OF REMOTE SENSING CAMERA

  • Jang Hong-Sul;Jeong Dae-Jun;Lee Seunghoon
    • 대한원격탐사학회:학술대회논문집
    • /
    • 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
    • /
    • pp.601-603
    • /
    • 2005
  • Refocusing methods are used to compensate optical performance degradation of high resolution satellite camera during on-orbit operation. Due to mechanical vibration during launch and thermal vacuum environment of space where camera is exposed, the alignment of optical system may have error. The focusing error is dominant of misalignment and caused by the de-space error of secondary mirror of catoptric camera, which is most sensitive to vibration and space environment. The high resolution camera of SPOT, Pleiades and KOMPSAT2 have refocusing device to adjust focusing during orbital operation while QuickBird of US does not use on orbit refocusing method. For the Korsch type optical configuration which is preferred for large aperture space remote sensing camera, secondary mirror and folding mirror are available as refocusing element.

  • PDF

디지털 샘플링 방법을 사용한 교류전압과 전류의 (Traceable AC Voltage and Current Measurements Using Digital Sampling Technique)

  • 위제싱허;박영태
    • 대한전기학회:학술대회논문집
    • /
    • 대한전기학회 2009년도 제40회 하계학술대회
    • /
    • pp.686_687
    • /
    • 2009
  • The traceability maintenance system for the AC voltage and current has been developed at the frequency range of 20 Hz to 100 Hz without using any compensation technique which is used at thermal converter (TC) ac-dc transfer system at low frequencies. The system uses a digital voltmeter (DVM) as a data acquisition system of the input waveform and stored data in memory. The developed algorithm acquires and processes the sampling data to calculate the root mean square (rms) value of the input voltage of DVM which operates at DC 10 V range for better accuracy. The best uncertainty of the AC voltage measurements is $3 {\mu}V/V$ within the frequency range. The best uncertainty of the AC current measurements is better than the $5 {\mu}A/A$ and mainly depend on the current to voltage converter, ac-dc current shunt or Current Transformer (CT), used for the measurement

  • PDF

AIGaN/GaN 이종접합 디바이스를 위한 GaN 에피층의 전기적 특성 (Electrical Characteristics of GaN Epi Layer on Sapphire Substrates for AIGaN/GaN Heterostructures)

  • 문도성
    • 한국전기전자재료학회논문지
    • /
    • 제15권7호
    • /
    • pp.591-596
    • /
    • 2002
  • In this work, epitaxial GaN is grown on sapphire substrate in AlGaN/GaN heterostructures. Deliberate oxygen doping of GaN grown by MOVPE has been studied. The electron concentration increased as a function of the square root of the oxygen partial Pressure. Oxygen is a shallow donor with a thermal ionization energy of $27\pm2 meV$ measured by temperature dependent Hall effects. A compensation ratio of $\theta$=0.3~0.4 was determined from Hall effect measurements. The formation energy of $O_N$ of $E^F$ =1.3eV determined from the experimental data, is lower than the theoretically predicted vague.

A Compact Active Channel Module Design for Active Phased Array Antenna System

  • Jung, Young-Bae
    • 전기전자학회논문지
    • /
    • 제17권4호
    • /
    • pp.393-397
    • /
    • 2013
  • This paper introduces the T/RX combined compact active channel module which is a key unit of the active phased array antenna(APAA) system. This module is mainly compoased of two parts for TX and RX fabricated on both sides of the active module for size reduction. The TX-part is primarily composed of a 3-stage amplifier, a microstrip phase shifter, a thermal compensation and a power detection circuit. The RX-part is composed of LNAs a microstrip phase shifter and BPFs for TX power rejection. Using the proposed design structure we can realized a compact active channel module having high performance.

Repetitive Compensation Control for AGC System By Using Pre-Pass Rolling Data

  • Kim, Hwan-Seong;Park, Jin-Seon;Lee, Sang-Dol;Lee, Keum-Jae;Park, Sung-Kwan
    • 제어로봇시스템학회:학술대회논문집
    • /
    • 제어로봇시스템학회 2001년도 ICCAS
    • /
    • pp.150.5-150
    • /
    • 2001
  • This paper deals with a modified repetitive control method for compensating automatic gauge control (AGC) to reduce the effect of skid mark which directly influence the quality of products in plate mill process. Since the skid mark on the plate have thermal difference, it makes a different stretching rate and deflection of thickness. Firstly, the (AGC) system and the plate mill process are described by considering function in each control levels. The skid mark of the plate in practical control fields is shown. Also, its frequency variation is given by on-line FFT analysis method. Secondly, a key idea of the modified repetitive control method with time varying period disturbance is represented and compared with standard repetitive control method. Lastly, in simulation ...

  • PDF

팬 모터 구동을 위한 집적화된 홀 센서 IC의 제작 및 특성 (Fabrication and Characteristics of the Integrated Hall Sensor IC For Driving Fan Motors)

  • 이철우
    • 대한전자공학회:학술대회논문집
    • /
    • 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
    • /
    • pp.73-76
    • /
    • 2002
  • In this paper we present an integrated Hail sensor It for fan motors, fabricated in industrial bipolar process. As a discrete Hall sensor and signal processing circuitry In the fan motor system were Integrated into single chip a temperature dependence of Hall sensitivity and Hall offset voltage can be compensated and cancelled by on-chip circuitry. We Propose a novel temperature compensation of Hall sensitivity with negative temperature coefficient (TC) using the differential amplifier gain with Positive TC. After a package of the chip was sealed using a plastic Package 20 Pins, the thermal and magnetic characteristics were investigated. The obtained experimental results are in agreement with analytical predictions and have more excellent performance than\ulcorner conventional the fan motor system using discrete Hall sensor.

  • PDF

Machine Tools 공간오차 분석을 위한 Bal1-bar Artifact 연구 (A Study on the Ball-Bar Artifact for the Volumetric Error Calibration of Machine Tools)

  • 이응석;구상서;박달근
    • 대한기계학회논문집A
    • /
    • 제28권7호
    • /
    • pp.986-991
    • /
    • 2004
  • For volumetric error measurement and calibration for machine tools, manufacturing machine or coordinate measuring machine (CMM), are studied using a Ball-bar artifact. A design of the Ball-bar is suggested manufactured by Invar, which is a low thermal expansion material, and precision steel balls. The uncertainty for the artifact method is discussed. A method of the Ball-bar artifact for obtaining 3-D position errors in CMM is proposed. The method of error vector measurement is shown using the Ball-bar artifact. Finally, the volumetric error is calculated from the error vectors and it can be used for Pitch error compensation in conventional NC machine and 3-D position Error map for calibration of NC machine tools.

Digital DC power supply for light accelerator

  • Kim, Yoon-Sik
    • Journal of Advanced Marine Engineering and Technology
    • /
    • 제38권8호
    • /
    • pp.1000-1003
    • /
    • 2014
  • There are 70 vertical and 70 horizontal correctors for Pohang Light Source. Until mid of 2000, power supplies for these correctors were based on 1990's technology, so the global orbit feedback system was not possible with poor 12 bit resolution. A new task force team was assembled to develop new power supplies with BESSY type DAC cards. After the project, two vertical correctors in each lattice were connected with new power supplies, and the global orbit feedback was available within the accuracy of 5 microns. However, this replacement was not enough to satisfy the beam stability requirement of 2 microns for PLS. We have launched another power supply design based on all digital technology. This attempt was completed within a year, and 80 units were assembled in house. Currently, the global orbit feedback system is running successfully with new digital power supplies and the compensation of chamber motion due to the thermal load by using digital displacement transducers attached on each BPMs.

저전력 CMOS 기준전류 발생회로 (A Low-Power CMOS Current Reference Circuit)

  • 김유환;권덕기;이종렬;유종근
    • 대한전자공학회:학술대회논문집
    • /
    • 대한전자공학회 2001년도 하계종합학술대회 논문집(2)
    • /
    • pp.89-92
    • /
    • 2001
  • In this paper, a simple low-power CMOS current reference circuit is proposed. The reference circuit includes parasitic pnp BJTs and resistors. Temperature compensation is made by adding a current component proportional to a thermal voltage to a current component proportional to a base-to-emitter voltage. The designed circuit has been simulated using a 0.25${\mu}{\textrm}{m}$ n-well CMOS process parameters. The simulation results show that the reference current is 34.96$mutextrm{A}$$\pm$0.04$mutextrm{A}$ in the temperature range of -2$0^{\circ}C$ to 12$0^{\circ}C$ The reference current varies less than 0.6% when the power supply voltage changes from 2.5V to 3.5V For $V_{DD=5V}$ and T=3$0^{\circ}C$ the power consumption is 520㎼ during normal operation but reduces to 0.l㎻ during power-down mode.

  • PDF