• Title, Summary, Keyword: Temperature Overshoot

Search Result 65, Processing Time 0.029 seconds

Cure simulation for a thick glass/epoxy laminate (유리섬유 강화 후판 복합재료의 경화공정 해석)

  • 오제훈;이대길
    • Proceedings of the Korean Society For Composite Materials Conference
    • /
    • /
    • pp.53-58
    • /
    • 2000
  • During the curing process of thick glass/epoxy laminates, a substantial amount of temperature lag and overshoot at the center of the laminates is usually experienced due to the large thickness and low thermal conductivity of the glass/epoxy composites. Also, it requires a longer time for full and uniform consolidation. In this work, temperature, degree of cure and consolidation of a 20mm thick unidirectional glass/epoxy laminate were investigated using an experiment and a 3-dimentional numerical analysis considering the exothermic reaction. From the experimental and numerical results, it was found that the experimentally obtained temperature profile agreed well with the numerical one and the cure cycle recommended by the prepreg manufacturer should be modified to prevent a temperature overshoot and to obtain full consolidation.

  • PDF

Cure simulation and Consolidation for a Thick Glass/Epoxy Laminate (유리섬유/에폭시 후판 복합재료의 경화공정 및 압밀해석)

  • O, Je-Hun;Lee, Dae-Gil
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.24 no.11
    • /
    • pp.2853-2865
    • /
    • 2000
  • During the curing process of thick glass/epoxy laminates, a substantial amount of temperature lag and overshoot at the center of the laminates is usually experienced due to the large thickness and low thermal conductivity of the glass/epoxy composites. Also, it takes a longer time for full and uniform consolidation. In this work, temperature, degree of cure and consolidation of a 20 mm thick unidirectional glass/epoxy laminate were investigated using an experiment and a 3-dimentional numerical analysis. From the experimental and numerical results, it was found that the experimentally obtained temperature profile agreed well with the numerical one, and the cure cycle recommended by the prepreg manufacturer should be modified to prevent a temperature overshoot and to obtain full consolidation.

Current overshoot operation of a REBCO magnet to mitigate SCF

  • Lee, Changhyung;Hahn, Seungyong;Bang, Jeseok;Cho, Jeonwook;Kim, Seokho
    • Progress in Superconductivity and Cryogenics
    • /
    • v.20 no.4
    • /
    • pp.65-69
    • /
    • 2018
  • Due to large in-field current carrying capacity and strong mechanical strength, a REBCO wire has been regarded as a viable high temperature superconductor (HTS) option for high field MRI and > 1 GHz (>23.5 T) NMR magnets. However, a REBCO magnet is well known to have an inherent problem of field inhomogeneity, so-called 'Screening Current induced magnetic Field (SCF)'. Recently, 'field shaking' and 'current overshoot operation' techniques have been successfully demonstrated to mitigate the SCF and enhance the field homogeneity by experiments. To investigate the effectiveness of current overshooting operation technique, a numerical simulation is conducted for a test REBCO magnet composed of a stack of double pancake coils using '2D edge-element magnetic field formulation' combined with 'domain homogenization' scheme. The simulation result demonstrates that an appropriate amount of current overshoot can negate the SCF. To verify the simulation results, current overshoot experiments are conducted for the REBCO magnet in liquid nitrogen. Experimental results also demonstrate the possible application of current overshoot technique to mitigate the SCF and enhance the field homogeneity.

High Temperature Compressive Deformation Behavior of the Bulk Metallic Glass Zr-Ti-Cu-Ni-Be Alloy (벌크 비정질 Zr-Ti-Cu-Ni-Be 합금의 고온 압축 변형 특성)

  • 이광석;하태권;안상호;장영원
    • Transactions of Materials Processing
    • /
    • v.10 no.7
    • /
    • pp.565-572
    • /
    • 2001
  • It is well known that a multicomponent $Zr_{4l.2}Ti_{13.8}Cu_{12.5}Ni_{10}Be_{22.5}$ bulk metallic glass alloy shows good bulk glass forming ability due to its high resistance to crystallization in the undercooled liquid state. DSC and XRD have been performed to confirm the amorphous structure of the master alloy. To investigate the mechanical properties and deformation behavior of the bulk metallic $Zr_{4l.2}Ti_{13.8}Cu_{12.5}Ni_{10}Be_{22.5}$ alloy, a series of compression tests has been carried out at the temperatures ranging from $351^{\circ}C$ to $461^{\circ}C$at the various initial strain rates from $2{\times}10^4s^1$ to $2{\times}10^2s^1$. Three types of nominal stress-strain curves have been identified such as linear stress-strain relationship meaning fracture at maximum stress, plastic deformation including stress overshoot and steady-state flow, plastic deformation without stress overshoot depending on the strain rate and test temperature. Also DSC analysis for the compressed specimens was carried out to investigate the change of structure, thermal stability and crystallization behavior for the various test conditions.

  • PDF

A study on the development of the velocity and temperature fields in a laminar flow through an eccentric annular ducts (偏心된 二重圓管의 環狀部를 지니는 層流流動에서의 連度場 및 溫度場의 確立에 대한 硏究)

  • 이택식;이상산
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.10 no.6
    • /
    • pp.861-869
    • /
    • 1986
  • A numerical study has been conducted on the development of the velocity and temperature fields in a laminar flow through an eccentric annular duct. A bipolar coordinates system is adopted, and a numerical program is developed to analyze 3-dimensional parabolic flow problems. In the analysis of the velocity field, the entrance length has been defined as the distance where the axial pressure gradient is greater than that of the developed velocity field by 5%. The dimensionless hydrodynamic entry length increases with increasing eccentricity. In the transverse flow fields, the reverse flow region along the wall due to the developing axial velocity near the entrance of the duct is found. In the analysis of the temperature field, the thermal entry length has been defined as the axial distance where the mean fluid temperature is 5% less than that of the developed temperature field. The dimensionless thermal entry length increases as eccentricity or Prandtl number increases. The overshoot of the mean Nusselt number over the developed value at the zero-temperature wall is encountered, and the rate of the overshoot increases with the increase of the eccentricity and Prandtl number.

Extraction of Effective Carrier Velocity and Observation of Velocity Overshoot in Sub-40 nm MOSFETs

  • Kim, Jun-Soo;Lee, Jae-Hong;Yun, Yeo-Nam;Park, Byung-Gook;Lee, Jong-Duk;Shin, Hyung-Cheol
    • JSTS:Journal of Semiconductor Technology and Science
    • /
    • v.8 no.2
    • /
    • pp.115-120
    • /
    • 2008
  • Carrier velocity in the MOSFET channel is the main driving force for improved transistor performance with scaling. We report measurements of the drift velocity of electrons and holes in silicon inversion layers. A technique for extracting effective carrier velocity which is a more accurate extraction method based on the actual inversion charge measurement is used. This method gives more accurate result over the whole range of $V_{ds}$, because it does not assume a linear approximation to obtain the inversion charge and it does not limit the range of applicable $V_{ds}$. For a very short channel length device, the electron velocity overshoot is observed at room temperature in 37 nm MOSFETs while no hole velocity overshoot is observed down to 36 nm. The electron velocity of short channel device was found to be strongly dependent on the longitudinal field.

Development of auto-tuning PID controller for Temperature Control systems and Its Application to Rapid Thermal Processor (온도제어용 자동동조 PID 제어기 설계와 RTP에의 적용)

  • 임재식;이영일
    • 제어로봇시스템학회:학술대회논문집
    • /
    • /
    • pp.62-62
    • /
    • 2000
  • An auto-tuning PID controller which is adequate for temperature control is developed based on relay-control and pole-placement Using the critical frequency which is obtained from relay-control parameters of assumed model are identified. Pole/zero-placement PID controller is designed for the identified model. The desired pole/zeros are determined so that the closed-loop has overshoot free step response. The developed auto-tuning PID controller was successfully applied to the temperature control of RTP.

  • PDF

Development of Temperature Control System for Semiconductor Test Handler II - Controller Design (반도체 테스트 핸들러의 온도제어 시스템 개발 II - 제어기 설계)

  • 김재용;강태삼;이호준;선기상
    • 제어로봇시스템학회:학술대회논문집
    • /
    • /
    • pp.77-80
    • /
    • 1997
  • In this paper presented is a temperature controller for a semiconductor test handler. Using ARMAX model and least square method, the chamber model for the design of a controller is identified through experiment. With the identified model an LQG/LTR controller is designed. Experiment with a real test handler demonstrated good performance in that its overshoot is small and response time is fast.

  • PDF

A Study on the Improvement of Electronic Controller for Computer Dryer Using Dual Processor (이중 프로세서를 이용한 컴퓨터 건조기의 전자 제어장치 성능 개선에 관한 연구)

  • 박세현
    • The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.9 no.5
    • /
    • pp.71-79
    • /
    • 1995
  • This paper describes the design and implementation of dryer controller using the dual processor. This system has higher performance of system recovery from the noise than the existing single processor dryer. And in this paper temperature control method of Dryer using on-off fuzzy logic is proposed to improve the overshoot of temperature in dryer. Experimental results shows that the performance of fuzzy controller is better than that of controller based upon on-off control method.

  • PDF