• Title/Summary/Keyword: 열회로

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A Study on Heat-transfer Characteristics the Shelter by Solar-heat Radiant (쉘터의 태양열 복사에 의한 열전달 특성에 관한 연구)

  • Shim, Dong-Hyouk;Noh, Kyung-Ho;Park, Jin-Yong;Lim, Young-Taek
    • Journal of the Korea Society for Simulation
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    • v.27 no.2
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    • pp.25-33
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    • 2018
  • When developing military equipment, it should be designed considering the temperature condition so that the operator can operate in a stable environment. The shelter for storing various military equipments is operated in various environments. The storage temperature and operating requirements of the test equipment and repair accessories shall be $-32^{\circ}C$ to $50^{\circ}C$ and the inside of the shelter shall be designed to meet the storage temperature and operating requirements. In this study, thermal analysis of a 2.5 ton military shelter operating under high temperature and solar heat conditions is performed considering MIL-STD-810G. The thermal analysis was applied by using the concept of heat resistance and heat circuit, and the solar thermal test was performed on the actually manufactured military shelter in order to verify the analysis results.

Design of Low Noise Readout Circuit for 2-D Capacitive Microbolometer FPAs (정전용량 방식의 이차원 마이크로볼로미터 FPA를 위한 저잡음 신호취득 회로 설계)

  • Kim, Jong Eun;Woo, Doo Hyung
    • Journal of the Institute of Electronics and Information Engineers
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    • v.51 no.10
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    • pp.80-86
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    • 2014
  • A low-noise readout circuit is studied for 2-D capacitive microbolometer focal plane arrays (FPAs). In spite of the merits of the integration method, a simple and effective pixelwise readout circuit without integration is used for input circuit because of a small pixel size and narrow noise bandwidth. To reduce the power consumption and the kT/C noise, which is the dominant noise of the capacitive microbolometer FPAs with small capacitance, a new correlated double sampling (CDS) is used for columnwise circuit. The proposed circuit has been designed using a $0.35-{\mu}m$ 2-poly 4-metal CMOS process for a microbolometer array with a pixel size of $50{\mu}m{\times}50{\mu}m$. The proposed circuit effectively reduces the kT/C noise and the other low-frequency noise of microbolometer, and the noise characteristics of the fabricated chip have been verified by measurements. The rms noise voltage of the proposed circuit is reduced from 30 % to 55 % compared to that of the simple readout input circuit, and the noise equivalent temperature difference (NETD) of the proposed circuit is very low value of 21.5 mK.

Characterization for Viscoelasticity of Glass Fiber Reinforced Epoxy Composite and Application to Thermal Warpage Analysis in Printed Circuit Board (유리섬유강화 복합재의 점탄성 특성 규명 및 인쇄회로기판 열변형해석에의 적용)

  • Song, Woo-Jin;Ku, Tae-Wan;Kang, Beom-Soo;Kim, Jeong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.2
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    • pp.245-253
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    • 2010
  • The reliability problems of flip chip packages subjected to temperature change during the packaging process mainly occur due to mismatches in the coefficients of thermal expansion as well as features with time-dependent material properties. Resin molding compounds like glass fiber reinforced epoxy composites used as the dielectric layer in printed circuit boards (PCB) strongly exhibit viscoelastic behavior, which causes their Young's moduli to not only be temperature-dependent but also time-dependent. In this study, the stress relaxation and creep tests were used to characterize the viscoelastic properties of the glass fiber reinforced epoxy composite. Using the viscoelastic properties, finite element analysis (FEA) was employed to simulate thermal loading in the pre-baking process and predict thermal warpage. Furthermore, the effect of viscoelastic features for the major polymeric material on the dielectric layer in the PCB (the glass fiber reinforced epoxy composite) was investigated using FEA.

Scalable AlGaN/GaN HEMTGs Model Including Thermal Effect (스케일링이 가능한 AlGaN/GaN HEMT 소자의 열 모델에 관한 연구)

  • 김동기;김성호;오재응;권영우
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.7
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    • pp.705-711
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    • 2003
  • In this Paper, 2${\times}$100 $\mu\textrm{m}$ AlCaN/GaN HEMT's(on sapphire substrate) large signal model including thermal effect was extracted. An equation based empirical model was employed to make large signal model for convergence and high speed. Pulsed I-V measurement was performed to extract thermal resistance and capacitance. Power amplifiers with 9 mm and 15 mm AlCaN/GaN HEMTS were designed using scaled modeling results of 2${\times}$100 $\mu\textrm{m}$ device respectively. From comparisons between measured and simulated data, the model considering of thermal effects gave better agreement than without one. It demonstrates that thermal modeling must be performed for power amplifier that uses large size transistors.

Air-side Heat Transfer and Friction Characteristics of Fined-tube Heat Exchangers under Heating Condition (핀-관 열교환기의 난방운전 시 공기측 열전달 및 마찰특성)

  • Kwon, Young Chul;Chang, Keun Sun;Ko, Kuk Won;Kim, Young Jae;Park, Byung Kwon
    • Applied Chemistry for Engineering
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    • v.17 no.5
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    • pp.476-482
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    • 2006
  • An experimental study has been performed to investigate the characteristics of air-side heat transfer and friction of a fined tube heat exchanger under heating conditions. Air enthalpy calorimeter was used to obtain the performance evaluation and analysis of the fined tube heat exchanger. Eight finned tube heat exchangers with slit fin, louver fin, and plain fin were used. The air-side heat transfer coefficient was calculated by the log-mean-temperature-difference. Air-side heat transfer and friction were presented in terms of j factor and friction factor on Reynolds number. From the experimental result, it was found that the variations of air-side heat transfer and friction of fined tube heat exchanger with the change of the fin configuration, row number, fin pitch, and tube circuit were obtained. j factor and friction factor decreased with Reynolds number increased. The tube circuit affected the air-side heat transfer and friction. In the case of slit and louver fin, j factor of 1st row was higher than that of 2nd row. But, with increasing Re, j factor was reversed. The characteristics of j factor and friction factor of 2nd row heat exchanger were different according to the kind of fins.

Automatic Tuning Architecture of RC Time-Constant due to the Variation of Integrated Passive Components (집적된 수동 소자 변동에 의한 RC 시상수 자동 보정 기법)

  • Lee, Sung-Dae;Hong, Kuk-Tae;Jang, Myung-Jun;Chung, Kang-Min
    • Journal of Sensor Science and Technology
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    • v.6 no.2
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    • pp.115-122
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    • 1997
  • In this paper, on-chp atomatic tuning circuit, using proposed integration level approximation technique, is designed to tuning of the variation of RC time-constant due to aging or temperature variation, etc. This circuit reduces the error, the difference between code values and real outputs of integrator, which is drawback of presented dual-slope tuning circuit and eliminates modulations of processing signals in integrated circuit due to fixed tuning codes during ordinary operation. This system is made up of simple integrator, A/D converter and digital control circuit and all capacitors are replaced by programed capacitor arrays in this system. This tuning circuit with 4 bit resolution achieves $-9.74{\sim}+9.68%$ of RC time constant error for 50% resistance variation.

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An implementation of NDIR type $CO_2$ gas sample chamber and measuring hardware for capnograph system in consideration of the time response characteristics (시간응답특성을 고려한 2광원 1센서 방식의 capnograph 시스템용 NDIR식 $CO_2$ 가스 챔버 설계 및 측정 회로의 구현)

  • Park, I.Y.;Lee, I.K.;Lee, S.K.;Kang, K.M.;Kang, S.W.;Cho, J.H.
    • Journal of Sensor Science and Technology
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    • v.10 no.5
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    • pp.279-285
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    • 2001
  • The capnograph system for determining the partial pressure of carbon dioxide in the blood of a patient was developed based on the NDIR(non-dispersive infrared) absorption technology. NDIR gas analyzing method requires an optical absorption chamber and signal processing hardware. In this paper, we have designed and implemented NDIR type $CO_2$ gas chamber in consideration of the time response characteristics and lamp chopping frequency. And we have implemented signal processing hardware using two infrared sources to reduce the thermal background effect. The implemented gas chamber and signal processing hardware were tested in the temperature variation experiment and human expiratory experiment. The results showed that the system could produce a stable output signal and a good $CO_2$ gas concentration curve like a typical capnogram.

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A 5.8GHz SiGe Down-Conversion Mixer with On-Chip Active Batons for DSRC Receiver (DSRC수신기를 위한 능동발룬 내장형 5.8GHz SiGe 하향믹서 설계 및 제작)

  • 이상흥;이자열;이승윤;박찬우;강진영
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.4A
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    • pp.415-422
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    • 2004
  • DSRC provides high speed radio link between Road Side Equipment and On-Board Equipment within the narrow communication area. In this paper, a 5.8 GHz down-conversion mixer for DSRC communication system was designed and fabricated using 0.8 ${\mu}{\textrm}{m}$ SiGe HBT process technology and RF/LO matching circuits, RF/LO input balun circuits, and If output balun circuit were all integrated on chip. The chip size of fabricated mixer was 1.9 mm${\times}$1.3 mm and the measured performance was 7.5 ㏈ conversion gain, -2.5 ㏈m input IP3, 46 ㏈ LO to RF isolation, 56 ㏈ LO to IF isolation, current consumption of 21 mA for 3.0 V supply voltage.

A 5.8 GHz SiGe Up-Conversion Mixer with On-Chip Active Baluns for DSRC Transmitter (DSRC 송신기를 위한 능동발룬 내장형 5.8 GHz SiGe 상향믹서 설계 및 제작)

  • Lee Sang heung;Lee Ja yol;Kim Sang hoon;Bae Hyun cheol;Kang Jin yeong;Kim Bo woo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.4A
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    • pp.350-357
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    • 2005
  • DSRC provides high speed radio link between Road Side Equipment and On-Board Equipment within the narrow communication area. In this paper, a 5.8 GHz up-conversion mixer for DSRC communication system was designed and fabricated using 0.8 m SiGe HBT process technology and IF/LO/RF matching circuits, IF/LO input balun circuits, and RP output balun circuit were all integrated on chip. The chip size of fabricated mixer was $2.7mm\times1.6mm$ and the measured performance was 3.5 dB conversion gain, -12.5 dBm output IP3, 42 dB LO to If isolation, 38 dB LO to RF isolation, current consumption of 29 mA for 3.0 V supply voltage.

The Development of Buck Type Electronic Ballast for 250W MHL and Dimming System (250W MHL용 Buck Type 전자식 안정기 및 Dimming 시스템 개발)

  • 박종연;박영길;정동열;김한수
    • The Transactions of the Korean Institute of Power Electronics
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    • v.7 no.1
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    • pp.30-40
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    • 2002
  • This paper studies the electronic ballast development for 250w MH lamps. We have improved the input power factor using a PFC IC. To provide the rating voltage required In the lamps, we have used the buck type dc-dc converter By this method, the stress of switching devices in inverter can be reduced. The inverter is the Full-Bridge type. To eliminate the acoustic resonance phenomena of MH lamps, we have added the high frequency sinewave voltage to the low frequency square-wave voltage to the lamp. We hove developed the igniter circuit using the L, C devices. We could control dimming of the lamp by varying the output voltage of the buck converter. The time of illuminating lamps and luminous intensity could be adjusted by season and time band. The buck converter output voltage can be controlled and the no load and over current situation were Protected by the development of the microprocessor Program.