• Title/Summary/Keyword: Transport Mechanism

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Simulation of Submicron MOSFET Using Hydrodynamic Model (Hydrodynamic model을 이용한 Submicron MOSFET의 Simulation)

  • 김충원;한백형;김경석
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.30A no.11
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    • pp.122-131
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    • 1993
  • In this paper, we have developed a submicron Si MOSFET simulator, which is physically based on the hydrodynamic energy transport mode. The simulator was used to investigate the nonstationary transport effects and the transient phenomena in submicron Si MOSFET's. It is found that the velocity overshoot and the carrier heating are dominant transport mechanism near the drain end of the channel and the transient phenomena is more retained in a long channel MOSFET.

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A Study on Interaction of Estuarial Water and Sediment Transport (하구수와 표사의 상호작용에 관한 연구)

  • Lee, H.;Lee, J.W.
    • Journal of Korean Port Research
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    • v.14 no.4
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    • pp.451-461
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    • 2000
  • The design and maintenance of navigation channel and water facilities of an harbor which is located at the mouth of river or at the estuary area are difficult due to the complexity of estuarial water and sediment circulation. Effects of deepening navigable waterways, of changing coastline configurations, or of discharging dredged material to the open sea are necessary to be investigated and predicted in terms of water quality and possible physical changes to the coastal environment. A borad analysis of the transport mechanism in the estuary area was made in terms of sediment property, falling velocity, concentration and flow characteristics. In order to simulate the transport processes, a two-dimensional finite element model is developed, which includes erosion, transport and deposition mechanism of suspended sediments. Galerkin’s weighted residual method is used to solve the transient convection-diffusion equation. The fluid domain is subdivided into a series of triangular elements in which a quadratic approximation is made for suspended sediment concentration. Model could deal with a continuous aggregation by stipulating the settling velocity of the flocs in each element. The model provides suspended sediment concentration, bed shear stress, erosion versus deposition rate and bed profile at the given time step.

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NOx Formation Characteristics in Diffusion, Partial Premixed and Premixed Jet flame (가스 연료의 연소 방식에 따른 NOx 생성 특성)

  • Choi, Young-Ho;Lee, Chang-Eon
    • 한국연소학회:학술대회논문집
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    • 1998.10a
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    • pp.155-164
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    • 1998
  • Numerical analysis was performed with multicomponent transport properties and detailed reaction mechanisms for axisymetric 2-D CH4 jet diffusion, partial premixed, premixed flame. Calculations were carried out twice with C2-Full Mechanism including prompt NO reaction in addition to the above C2-Thermal NO Mechanism. The role of thermal NO mechanism and prompt NO mechanism on each flame's NO production is investigated by using the numerical result. The NOx production of each flame were evaluated Quantitatively in terms of the NOx emission index

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Transport Loss Characteristics of a Bi-2223 Tape in External AC Magnetic Fields (외부 교류지장에 대한 Bi-2223테이프의 통전손실 특성)

  • Ryu, Kyung-Woo;Kim, Chang-Wan;Cha, Guee-Soo
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.50 no.6
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    • pp.290-295
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    • 2001
  • The transport loss of a Bi-2223 tape exposed to external magnetic fields was investigated. The results show that the transport loss is independent on voltage lead arrangements in case the magnetization loss is compensated. A serous increase of the transport loss due to external AC magnetic field is observed. The loss is described well by dynamic resistance loss in relatively high fields, but another mechanism than the dynamic resistance must be responsible for the increase of the loss in low fields. The transport loss is also dependent strongly on the orientation of the external fields.

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The Study of Luminescence Efficiency by change of OLED's Hole Transport Layer

  • Lee, Jung-Ho
    • International Journal of Precision Engineering and Manufacturing
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    • v.7 no.2
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    • pp.52-55
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    • 2006
  • The OLEDs(Organic Light-Emitting Diodes) structure organizes the bottom layer using glass, ITO(indium thin oxide), hole injection layer, hole transport layer, emitting material layer, electron transport layer, electron injection layer and cathode using metal. OLED has various advantages. OLEDs research has been divided into structural side and emitting material side. The amount of emitting light and luminescence efficiency has been improved by continuing effort for emitting material layer. The emitting light mechanism of OLEDs consists of electrons and holes injected from cathode and anode recombination in emitting material layer. The mobilities of injected electrons and holes are different. The mobility of holes is faster than that of electrons. In order to get high luminescence efficiency by recombine electrons and holes, the balance of their mobility must be set. The more complex thin film structure of OLED becomes, the more understanding about physical phenomenon in each interface is needed. This paper observed what the thickness change of hole transport layer has an affection through the below experiments. Moreover, this paper uses numerical analysis about carrier transport layer thickness change on the basis of these experimental results that agree with simulation results.

A Study on Transport Mechanism of the Ultrasonic Transporting System using Laser Scanning Vibrometer (Laser Scanning Vibrometer를 이용한 초음파 이송시스템의 이송 메커니즘에 관한 연구)

  • 정상화;신병수
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.841-844
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    • 2003
  • In the semiconductor and the optical industry a new transport system which can replace the conventional sliding system is required. These systems are driven by magnetic field and conveyer belt. The magnetic field damages semiconductor and contact force scratches the optical lens. The ultrasonic wave driven system can solve these problem. In this paper, the vibration behavior of flexural beam in the ultrasonic transport system is verified using Laser Scanning Vibrometer. The experiments for verifying vibration are performed in three conditions such as in the maximum transport speed, in the zero speed, and in the change of transport direction.

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Enhancing the Efficiency of Core/Shell Nanowire with Cu-Doped CdSe Quantum Dots Arrays as Electron Transport Layer (구리 이온 도핑된 카드뮴 셀레나이드 양자점 전자수송층을 갖는 나노와이어 광전변환소자의 효율 평가)

  • Lee, Jonghwan;Hwang, Sung Won
    • Journal of the Semiconductor & Display Technology
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    • v.19 no.4
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    • pp.94-98
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    • 2020
  • The core/shell of nanowires (NWs) with Cu-doped CdSe quantum dots were fabricated as an electron transport layer (ETL) for perovskite solar cells, based on ZnO/TiO2 arrays. We presented CdSe with Cu2+ dopants that were synthesized by a colloidal process. An improvement of the recombination barrier, due to shell supplementation with Cu-doped CdSe quantum dots. The enhanced cell steady state was attributable to TiO2 with Cu-doped CdSe QD supplementation. The mechanism of the recombination and electron transport in the perovskite solar cells becoming the basis of ZnO/TiO2 arrays was investigated to represent the merit of core/shell as an electron transport layer in effective devices.

Mechanism on suppression in vortex-induced vibration of bridge deck with long projecting slab with countermeasures

  • Zhou, Zhiyong;Yang, Ting;Ding, Quanshun;Ge, Yaojun
    • Wind and Structures
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    • v.20 no.5
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    • pp.643-660
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    • 2015
  • The wind tunnel test of large-scale sectional model and computational fluid dynamics (CFD) are employed for the purpose of studying the aerodynamic appendices and mechanism on suppression for the vortex-induced vibration (VIV). This paper takes the HongKong-Zhuhai-Macao Bridge as an example to conduct the wind tunnel test of large-scale sectional model. The results of wind tunnel test show that it is the crash barrier that induces the vertical VIV. CFD numerical simulation results show that the distance between the curb and crash barrier is not long enough to accelerate the flow velocity between them, resulting in an approximate stagnation region forming behind those two, where the continuous vortex-shedding occurs, giving rise to the vertical VIV in the end. According to the above, 3 types of wind fairing (trapezoidal, airfoil and smaller airfoil) are proposed to accelerate the flow velocity between the crash barrier and curb in order to avoid the continuous vortex-shedding. Both of the CFD numerical simulation and the velocity field measurement show that the flow velocity of all the measuring points in case of the section with airfoil wind fairing, can be increased greatly compared to the results of original section, and the energy is reduced considerably at the natural frequency, indicating that the wind fairing do accelerate the flow velocity behind the crash barrier. Wind tunnel tests in case of the sections with three different countermeasures mentioned above are conducted and the results compared with the original section show that all the three different countermeasures can be used to control VIV to varying degrees.

Effects of Cadmium on Glucose Transport in L6 Myocytes (L6 근육세포에서 포도당 수송능에 미치는 $CdCl_2$의 영향)

  • Kang Donghee;Khil Lee-Yong;park Kwangsik;Lee Byung-Hoon;Moon Chang-Kiu
    • Environmental Analysis Health and Toxicology
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    • v.20 no.1
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    • pp.75-85
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    • 2005
  • This study was aimed to know the effect of cadmium chloride (CdCl₂) on glucose transport in L6 myotube and its action mechanism. CdCl₂ increased the 2-deoxy- (l-3H)-D-glucose (2-DOG) uptake 1.9 and 2.4 fold at 10 and 25 μM respectively. To investigate the stimulating-mechanism of glucose transport induced by CdCl₂, the wortmannin and PD98059 were used as PI3K (phosphatidylinositol 3-kinase) inhibitor and MAPK inhibitor respectively, which did not affect 2-DOG uptake. This fact suggests that CdCl₂ induced 2-DOG uptake may not be concerned to the insulin signalling pathway. Whereas nifedipine, a calcium channel blocker, and trifluoperazine, a calmodulin inhibitor, were found to inhibit the 2-DOG uptake stimulted by CdCl₂. In addition, we also measured the ROS (reactive oxygen species) production and GSH level in L6 myotube to investigate the correlation between the glucose uptake and ROS. CdCl₂(25 μM) increased ROS generation approximately 1.5 fold and changed the cellular GSH level, but GSSG/GSH ratio remained unchanged. CdCl₂ stimulated 2-DOG uptake and ROS generation were inhibited by N-acetylcystein. And BSO pretreatment, a potent inhibitor of γ-GCS, resulted in the dramatic decrease of 2-DOG uptake and also the increase of the sensitivity to cadmium cytotoxicity. The obtained results suggest that CdCl₂-stimulated glucose uptake might be based on the activation of HMP shunt as an antioxidant defense mechanism of the cells.