• Title/Summary/Keyword: Transition curve

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Analysis of MICC, ELA TFT performance transition according to substrate temperature and gate bias stress time variation (온도 변화 및 Gate bias stress time에 따른 MICC, ELA TFT성능 변화 비교 분석)

  • Yi, Seung-Ho;Lee, Won-Baek;Yi, Jun-Sin
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.06a
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    • pp.368-368
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    • 2010
  • Using TFTs crystallized by MICC and ELA, electron mobility and threshold voltage were measured according to various substrate temperature from $-40^{\circ}C$ to $100^{\circ}C$. Basic curve, $V_G-I_D$, is also measured under various stress time from 1s to 10000s. Consequently, due to the passivation effect and number of grains, mobility of MICC is varied in the range of -8% ~ 7.6%, while that of ELA is varied from -11.04% ~ 13.25%. Also, since $V_G-I_D$ curve is dominantly affected by grain size, active layer interface, the graph remained steady under the various gate bias stress time from 1s to 10000s. This proves the point that MICC can be alternative technic to ELA.

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A Study on Laser Cutting Path Generation by Image Processing (이미지처리를 통한 레이저 가공경로생성에 관한 연구)

  • 박정호;이희관;양균의;김공묵
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.11a
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    • pp.934-938
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    • 2000
  • This paper presents a laser cutting of 2D image. 2D image in pixel graphic format is converted into vector graphic image by image processing. Bitmap graphics are made easily, but can not being used in application works for geometry transition. The Sobel's Edge detection method is used to find boundary points on 2D image. The points are fitted into curves with sampling and filtering. Sampling can provide efficient computation and filtering reconstuct features in image. The NC code is generated on MURBS curve of the points. Also, the offset of contour and cutting conditions are considered.

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A study on the Stick-slip Characteristic of Machine Tool Feeding System. (공작기계 이송계의 Stick-Slip 특성에 관한 연구)

  • Park, Jong-Gwon;Lee, Hu-Sang
    • 한국기계연구소 소보
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    • s.18
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    • pp.29-35
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    • 1988
  • When low sliding velocities in the boundary lubrication range are operating, irregular movements frequently occur which are a result of the stick-slip phenomenon. Such slide motions are undesirable in precision machine tools, particularly with feed back systems used in numerical and adaptive control machine tools. Accordingly, this paper reports analytical and experimental studies in the stick-slip characteristic of machine tool feeding system. The main conclusions of this study are as follows; The tendency towards stick-slip effects may be reduced by; 1). Reducing the drop in friction coefficient in the Stribeck curve(on the rising part of the friction characteristic at higher sliding speeds, the system is stable all the time) 2). Reducing the transition velocity by the use of a higher viscosity lubricating oil. 3). Increasing the stiffness(Damping)and reducing normal load(Sliding mass) Therefore, the Critical velocity is decided from the above conclusions and in designing of machine tool, feed rates(sliding velocity)must be design the more than critical velocity.

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Reference Point Projection Method for Improved Dynamics of Solar Array Hardware Emulation

  • Wellawatta, Thusitha;Choi, Sung-Jin
    • Proceedings of the KIPE Conference
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    • 2018.07a
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    • pp.126-128
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    • 2018
  • Solar array simulator (SAS) is a special DC power supply that regulates the output voltage or current to emulate characteristics of photovoltaic (PV) panels. Especially, the control of SAS is a challenging task due to the nonlinearity in the output curve, which is dependent on irradiance as well as temperature and is determined by panel materials. Conventionally, both current-mode control and voltage-mode control should be alternated by partitioning the operating curve into multiple sections, which is not only for the measurement noise problem with the feedback sensing but also for the control stability issue near the maximum power point. However, the occurrence of transition among different controllers may deteriorate the overall performance. To eliminate the mode transitions, a novel single controller scheme has been introduced in this paper, where the reference operating projection technique enables simple, smooth and numerically stable control. Theoretical consideration on the loop stability issue is discussed and the performance is verified experimentally for the emulation of a PV panel data in view of stability and response speed.

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Evaluation of Impact Characteristics for High Strength Structural Steel at Low Temperature (고강도 구조용강의 저온 충격특성 평가)

  • 김재훈;김덕회;김후식;조성석;전병완;심인옥
    • Journal of the Korean Society of Propulsion Engineers
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    • v.5 no.3
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    • pp.1-9
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    • 2001
  • Impact tests are performed on the high strength structural steel that is being developed for the submarine material. Especially, the impact characteristics of this structural steels at low temperatures are investigated by charpy impact testing. Hyperbolic tangent curve fitting method is used to evaluate the LSE(lower shelf energy), USE(upper shelf energy) and DBTT(ductile-brittle transition temperature). Proportional equations between charpy impact energy and lateral expansion are obtained using the test results. Effect of temperature on the fracture appearance is investigated by using SEM.

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Analytical Formulation for the Everett Function

  • Hong, Sun-Ki;Kim, Hong-Kyu;Jung, Hyun-Kyo
    • Journal of Magnetics
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    • v.2 no.3
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    • pp.105-109
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    • 1997
  • The Preisach model neds a density function or Everett function for the hysterisis operator to simulate the hysteresis phenomena. To obtain the function, many experimental data for the first order transition curves are required. However, it needs so much efforts to measure the curves, especially for the hard magnetic materials. By the way, it is well known that the density function has the Gaussian distribution for the interaction axis on the Preisach plane. In this paper, we propose a simple technique to determine the distribution function or Everett function analytically. The initial magnetization curve is used for the distribution of the Everett function for the coercivity axis. A major, minor loop and the initial curve are used to get the Everett function for the interaction axis using the Gaussian distribution function and acceptable results were obtained.

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A mesoscale model for concrete to simulate mechanical failure

  • Unger, Jorg F.;Eckardt, Stefan;Konke, Carsten
    • Computers and Concrete
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    • v.8 no.4
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    • pp.401-423
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    • 2011
  • In this paper, a mesoscale model of concrete is presented, which considers particles, matrix material and the interfacial transition zone (ITZ) as separate constituents. Particles are represented as ellipsoides, generated according to a prescribed grading curve and placed randomly into the specimen. In this context, an efficient separation procedure is used. The nonlinear behavior is simulated with a cohesive interface model for the ITZ and a combined damage/plasticity model for the matrix material. The mesoscale model is used to simulate a compression and a tensile test. Furthermore, the influence of the particle distribution on the loaddisplacement curve is investigated.

A Study on the Parameters Effecting on the Derailment Factor of Running Train on the Curved Track (곡선부에서 탈선계수에 영향을 미치는 매개변수들에 대한 연구)

  • Song, Bong-Hwan;Yang, Shin-Chu;Kang, Yun-Suk
    • Proceedings of the KSR Conference
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    • 2004.10a
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    • pp.348-356
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    • 2004
  • In this paper, Analysis of parameters effecting on the derailment factor was conducted in oder to deduce technical requisites have to be reflected in design of Track and rolling-stocks because it is important to grasp the risk of derailment quantitatively. And then go far toward becoming practical study with that select two section of sharp curved track of actual train in service, incheon Metro Line 1 and make field research in condition of vehicles and track and analysis As a result of parameter study, the following conclusions were obtained. The radius of curve and Cant is in inverse proportion to the derailment factor, but as train operation velocity, standard deviation of alignment irregularity and the ratio lateral force : wheel load of the inside track increase, the derailment factor rise. In the investigation for the derailment safety of incheon Metro Line 1, the derailment factor was below 0.43 in both section R=200 and R=300, so that it proved safe compare with allowance limits 0.8, but it appeared that risk of the derailment in second transition curve is the highest among the entire curve.

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Structural and Electrical Properties of RaRuO$_3$ Thin Film for Electrode of Ferroelectric Capacitors (강유전체 캐패시터 전극으로의 BaRuO$_3$박막의 구조적 및 전기적 특성)

  • 박봉태;구상모;문병무
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.12 no.1
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    • pp.56-61
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    • 1999
  • Highly conductive oxide films of BaRuO$_3$ have been grown heteroepitaxially on (100) LaAlO$_3$ single crystalline substrates by using pulsed laser deposition. The films are c-axis oriented with an in-plane epitaxial relationship of <010><100>BaRuO$_3$ // <110>LaAlO$_3$. Atomic force microscopy (AFM) observation shows that they consist of a fine-arranged network of grains and have a mosaic microstructure. Generally temperature-dependent resistivity shows the transition from metallic curve to semiconductor-metallic twofold curve by the deposition conditions for Ru oxide based materials like SrRuO$_3$, CaRuO$_3$, BaRuO$_3$, etc.. This twofold curve comes from the structural similarity of Ru oxide based materials including BaRuO$_3$. We find that the distance of Ru-Ru bonding in the unit cell of BaRuO$_3$ as well as the grain boundary scattering could be the two important causes of these interesting conductive properties.

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$^{3}$He Solid-Liquid Melting Pressure Thermomety ($^{3}$He의 고체-액체 융해압력 측정)

  • 김상보;최창호;이일수;김동락
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 1999.02a
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    • pp.161-164
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    • 1999
  • $^{3}$He melting curve thermometer is made, tested, and compared with Greywall scale. The experimental results show that we can identify the temperature within a few percentage. To improve the accuracy of our thermometer we need temperature fixed points like $^{3}$He superfluid phase transition temperature.

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