• Title/Summary/Keyword: Transport Mechanism

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Electrical Properties of ZnTe-lnSb Heterojunctions (ZnTe-InSb Heterojunction의 전기적 특성)

  • 김화택
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.12 no.4
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    • pp.35-40
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    • 1975
  • The Zn7e-lnSb heterojunctions was prepared by interface alloying technique. The structure of this beterojunction had p-i-n which semi-insulating ZnTe laver at interface of this heterojunction was formed by diffusing In of InSb into ZnTe crystal. The current transport mechanism of this heterojunction was Spacecharge-Limited-Current(SCLC) mechanism by hole at semi-insulating ZnTe layer. The hole wart injected from valence band of p- type SnTe crystal. Orange color electroluminescence was observed at this heterojunction when forward and reversed bias voltage applied.

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An Effective Emergency Message Delivery Mechanism for VANET (VANET에서의 효율적인 긴급 메시지 전송 기법)

  • Hwang, Jeong-Hee;Choe, Jong-Won
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.11 no.4
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    • pp.86-94
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    • 2012
  • VANETs can provide traffic warring service to help drivers drive safely based on the information of the traffic condition. The driver can drive safely through the warning service information provided by the VANET and know the traffic condition exactly more than through only the sight of driver. In this paper we suggest a new mechanism of updating the table to broadcast the message more rapidly based on the table driven method as the way of sending the emergency message in the VANETs. When updating the table, nodes sends only based on the message transmission success rate. In the result of simulation we could find that the suggested mechanism would reduce the delay time of the emergency message broadcast compared to the existing mechanism.

An End-to-End Mobility Support Mechanism based on mSCTP (mSCTP를 이용한 종단간 이동성 지원 방안)

  • 장문정;이미정;고석주
    • Journal of KIISE:Information Networking
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    • v.31 no.4
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    • pp.393-404
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    • 2004
  • Recently, mSCTP (Mobile SCTP) has been proposed as a transport layer approach for supporting mobility. mSCTP is based on the ‘multi-homing’ feature of Stream Control Transmission Protocol(SCTP), and utilize the functions to dynamically add or delete IP addresses of end points to or from the existing connectionin order to support mobility. In this paper, we propose a mechanism to determine when to add or delete an W address, utilizing the link layer radio signal strength information in order to enhance the performance of mSCTP We also propose a mechanism for a mobile node to initiate the change of data delivery path based on link layer radio signal strength information. In addition, if it takes long time to acquire new data path, we propose an approach for reducing handover latency. The simulation results show that the performance of proposed transport layer mobility support mechanism is competitive compared to the traditional network layer mobility supporting approach. Especially, when the moving speed of mobile node is fast, it shows better performance than the traditional network layer approaches.

LIQUID CRYSTALLINE POLYURETHANES. PHYSICOCHEMICAL CHARACTERISTICS AND PERVAPORATION PROPERTIES

  • A-Grabczyk, Aleksandra Wolibsk
    • Proceedings of the Membrane Society of Korea Conference
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    • 1996.04a
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    • pp.30-32
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    • 1996
  • Although the transport of small molecules through polymer membranes has been extensively studied for a long time, understanding of the transport mechanism is still far from satisfactory. This in turn makes difflcult the search for new membrane materials with the desired transport characteristics. Therefore it is of the utmost interest to study the correlations between a polymer's structure and morphology and its transport properties. Generally, polyurethanes serve as excellent polymer materials for such studies since their physical and chemical properties can be widely and systematically modified by varying the length, composition and chemical structure of the hard and soft segments. In this paper liquid crystalline polyurethanes are presented as new membrane materials for liquld separation and their transport properties with respect to molecular and supermolecular-structure are discussed.

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The Influence of External Magnetic Field on Transport Loss in a Bi-2223 tape (외부자계가 Bi-2223테이프의 통전손실에 미치는 영향)

  • 김창완;한형주;류경우;최병주
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2001.02a
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    • pp.169-171
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    • 2001
  • The transport loss of a Bi-2223 tape exposed to external magnetic field was investigated. The results show that the transport loss is independent on voltage lead arrangements in case the magnetization loss is compensated. An serious increase of the transport loss due to external magnetic fields 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 applied field.

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Transport of Metal Ions Through the Crosslinked Chitosan Membrane (가교 Chitosan막에 의한 금속 이온의 투과 특성)

  • Kim, Chong-Bae
    • Applied Chemistry for Engineering
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    • v.4 no.2
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    • pp.416-422
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    • 1993
  • In order to prepare high performance polymeric membrane, the crosslinked chitosan(C. Chitosan)membrane was prepared, the transport and the selective separation of the metal ions through the membrane were investigated. It was observed that the transport rates of the metal ions through the membrane increased according to the decreasing of the initial pH in downstream solution. Proton pump mechanism for this transport phenomenon was suggested. The transport selectivity is dependent on the selective adsorption resulting from the complex formation of chitosan with each metal ion. The separatin factor(${\alpha}_{Cu}{^{2+}}$) for the membrane was 9.5.

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Effects of Fracture Intersection Characteristics on Transport in Three-Dimensional Fracture Networks

  • Park, Young-Jin;Lee, Kang-Kun
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2001.09a
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    • pp.27-30
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    • 2001
  • Flow and transport at fracture intersections, and their effects on network scale transport, are investigated in three-dimensional random fracture networks. Fracture intersection mixing rules complete mixing and streamline routing are defined in terms of fluxes normal to the intersection line between two fractures. By analyzing flow statistics and particle transfer probabilities distributed along fracture intersections, it is shown that for various network structures with power law size distributions of fractures, the choice of intersection mixing rule makes comparatively little difference in the overall simulated solute migration patterns. The occurrence and effects of local flows around an intersection (local flow cells) are emphasized. Transport simulations at fracture intersections indicate that local flow circulations can arise from variability within the hydraulic head distribution along intersections, and from the internal no flow condition along fracture boundaries. These local flow cells act as an effective mechanism to enhance the nondiffusive breakthrough tailing often observed in discrete fracture networks. It is shown that such non-Fickian (anomalous) solute transport can be accounted for by considering only advective transport, in the framework of a continuous time random walk model. To clarify the effect of forest environmental changes (forest type difference and clearcut) on water storage capacity in soil and stream flow, watershed had been investigated.

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Study of Hydraulic Transport of Sand-water Mixture by a Dredging Test Loop (준설시험루프를 이용한 모래-물 혼합물 배송에 관한 연구)

  • Lee, Man-Soo;Park, Young-Ho;Lee, Young-Nam;Chung, Choong-Ki
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.03a
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    • pp.1504-1511
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    • 2005
  • The efficiency of the hydraulic transport of soil-water mixtures is an important factor in designing and operating a pump & pipeline system and is directly connected with dredging cost and working period. However, the hydraulic transport mechanism in the slurry flow inside the pipeline such as frictional losses, specific energy consumption, deposition velocity has not been well established. In this study a new dredging test loop system was designed and built. It is composed of a slurry pipeline with pipes of different diameters, a centrifugal slurry pump and a diesel engine connected with the slurry pump. and equipped with modern measuring facilities that enable to measure all important characteristics of a transportation system. The objective of this paper is to discuss the efficiency of the hydraulic transport of the Jumoonjin sand-water mixtures in the dredging test loop and to present simple equations induced from the test results of the loop that can express the transport product and the transport productivity.

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Pharmacokinetic Modelling and Simulation of the Counter-transport in the Hepatic Transport of Organic Anions (음이온계 약물의 간수송과정에 있어서 대향수송의 약물동력학적 모델링 및 시뮬레이션)

  • Song, Suk-Gil;Lee, Jun-Seup;Chung, Youn-Bok
    • YAKHAK HOEJI
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    • v.49 no.4
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    • pp.275-283
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    • 2005
  • The purpose of the present study was to kinetically investigate the carrier-mediated uptake in the hepatic transport of organic anions, and to simulate the 'in vivo counter-transport' phenomena, using kinetic model which was developed in this study. The condition that the mobility of carrier-ligand complex is greater than that of free carrier is not essential for the occurrence of 'counter-transport' phenomenon. To examine the inhibitory effects on the initial uptake of organic anions by the liver, it is necessary to judge whether the true counter-transport mechanism (trans-stimulation) is working or not. Effects of bromophenol blue (BPB) or bromosulfophthalein (BSP) on the plasma disappearance curves of a 1-anilino-8-naphthalene sulfonate (ANS) were then kinetically analyzed based on a flow model, in which the ligand is eliminated only from the peripheral compartment (liver compartment). Moreover, 'in vivo counter-transport' phenomena were simulated based on the perfusion model which incorporated the carrier-mediated transport and the saturable intracellular binding. The 'in vivo counter-transport' phenomena in the hepatic transport of a organic anions were well demonstrated by incorporating the carrier-mediated process. However, the 'in vivo counter-transport' phenomena may be also explained by the enhancement of back diffusion due to the displacement of intracellular binding. In conclusion, one should be more cautious in interpreting data obtained from so-called 'in vivo counter-transport' experiments.