• Title/Summary/Keyword: Stopped flow

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Effect of the Plasma-assisted Patterning of the Organic Layers on the Performance of Organic Light-emitting Diodes

  • Hong, Yong-Taek;Yang, Ji-Hoon;Kwak, Jeong-Hun;Lee, Chang-Hee
    • Journal of Information Display
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    • v.10 no.3
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    • pp.111-116
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    • 2009
  • In this paper, a plasma-assisted patterning method for the organic layers of organic light-emitting diodes (OLEDs) and its effect on the OLED performances are reported. Oxygen plasma was used to etch the organic layers, using the top electrode consisting of lithium fluoride and aluminum as an etching mask. Although the current flow at low voltages increased for the etched OLEDs, there was no significant degradation of the OLED efficiency and lifetime in comparison with the conventional OLEDs. Therefore, this method can be used to reduce the ohmic voltage drop along the common top electrodes by connecting the top electrode with highly conductive bus lines after the common organic layers on the bus lines are etched by plasma. To further analyze the current increase at low voltages, the plasma patterning effect on the OLED performance was investigated by changing the device sizes, especially in one direction, and by changing the etching depth in the vertical direction of the device. It was found that the current flow increase at low voltages was not proportional to the device sizes, indicating that the current flow increase does not come from the leakage current along the etched sides. In the etching depth experiment, the current flow at low voltages did not increase when the etching process was stopped in the middle of the hole transport layer. This means that the current flow increase at low voltages is closely related to the modification of the hole injection layer, and thus, to the modification of the interface between the hole injection layer and the bottom electrode.

The Reduced Model Test for the Determination of Ventilation Velocity to Prevent Backflow in Uni-directional Road Tunnel during a Fire Disaster (일방향 도로터널내 화재 발생시 역류를 막는 환기속도결정에 관한 축소모형실험)

  • 유영일;이희근
    • Tunnel and Underground Space
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    • v.8 no.2
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    • pp.107-117
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    • 1998
  • In the case of a fire disaster in a uni-directional road tunnel, it is important to determine the critical ventilation velocity to prevent the backflow travelling toward the tunnel exit where vehicles are stopped. The critical ventilation velocity is horizontal velocity to prevent hot smoke from moving toward the tunnel exit. According to Froude modelling, the model tunnel whcih was 300mm in diameter and 21 m in length was made of acryl tubes. Inner section of acryl tubes was clothed with polycarbonate. 1/20 scaled model vehicles were installed to simulate the situation that vehicles are stopped in the tunnel exit. Methanol in a pool type burner was burned in the middle of tunnel to simulate a fire hazard. In this study, the basis of determining the critical ventilation velocity is the ventilation flow rate that is able to maintain the allowable CO concentration in the tunnel section. We assumed that the allowable CO concentration was backflow dispersion index. Futhermore, We intended to find out CO distribution and temperature distribution according as we changed ventilation velocity. The results of this study were that no backflow happened when ventilation velocity was 0.52 m/s in the case of 5.75 kW. If we adapt these results of a fire disaster releasing 10MW heat capacity in real tunnel which is 400m in length, no backflow happens when ventilation velocity is 2.31m/s. After we figured out dimensionless heat release rate and dimensionless ventilation velocity of model test and those of real test to verify experimental correctness, we tried to find out correlation between experimental results of model tunnel and those of real tunnel.

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Numerical Analysis on Velocity Fields around Seabed Tiller for the Improvement of Seabed Soil (해저 토질 개선을 위한 해저경운기 주변의 속도장에 대한 수치해석)

  • Kim, Jang-Kweon;Oh, Seok-Hyung;Kim, Jong-Beom;Chung, Sang-Ok
    • Journal of Power System Engineering
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    • v.21 no.2
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    • pp.48-56
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    • 2017
  • The steady-state, incompressible and three-dimensional numerical analysis was carried out to evaluate the velocity fields around the seabed tiller used for the improvement of the seabed soil and the pulling force and buoyancy generated by driving the seabed tiller. The turbulence model used in this study is a realizable $k-{\varepsilon}$ well known to be excellent for predicting the performance of the flow separation and recirculation flow as well as the boundary layer with rotation and strong back pressure gradient. As a results, a typical vortex pair appears near the adjacent rotor vane tip. When the current is stopped, there is no force when pulling the seabed tiller, but when the current flows at 1.2 knots, the force acts on the downstream side and the pulling force is much greater. In stationary currents, the buoyancy of the seabed tiller acts more strongly towards the seabed as the number of rotations of the rotor increases, but acts more strongly toward the sea surface at 1.2 knots of current.

A Study on Signal Control Algorithms using Internal Metering for an Oversaturated Network (내부 미터링을 이용한 과포화 네트워크 신호제어 알고리즘 연구)

  • Song, Myeong-Gyun;Lee, Yeong-In
    • Journal of Korean Society of Transportation
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    • v.25 no.6
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    • pp.185-196
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    • 2007
  • The aim of this research is to develop a signal control algorithm using internal metering to minimize total delay that vehicles go through, in case a network is oversaturated. To calculate total delay on the network, the authors first detect vehicles' arrivals and departures in the network through the detecting system, and chase the vehicles' flow in the links with a platoon dispersion model. Following these, the authors calculate the queue length in all the inks of the network through the chase of vehicles, deduce the stopped time delay, and finally convert the stopped time delay to the approach delay with a time-space diagram. Based on this calculated delay, an algorithm that calculates the level of the internal metering necessary to minimize the deduced approach delay is suggested. To verify effectiveness of this suggested algorithm, the authors also conduct simulation with the micro-simulator VISSIM. The result of the simulation shows that the average delay per vehicle is 82.3 sec/veh and this delay is lower than COSMOS (89.9sec/veh) and TOD (99.1sec/veh). It is concluded that this new signal control algorithm suggested in this paper is more effective in controlling an oversaturated network.

Review of Reaction Drive Rotor System Sizing Methodology (반작용 구동로터 시스템의 사이징 방법론에 대한 고찰)

  • Ali, Freshipali Rasheeth;Jeon, Kwon-Su;Lee, Jae-Woo
    • 한국항공운항학회:학술대회논문집
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    • 2016.05a
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    • pp.9-13
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    • 2016
  • Reaction drive rotor system is capable of providing hover and low speed capabilities to different aircraft concepts such as stopped rotor wing, canard rotor wing, compound gyroplane etc. Existing sizing and analysis tools for shaft drive rotor system cannot be applied directly to this system. The available methodologies to size this system were reviewed. Power available calculation procedure and factors affects it were addressed prior to sizing process. Various design issues of this system due to interrelationship of internal gas flow dynamics and rotor external aerodynamics was discussed. Finally, a modification that is required in existing sizing methodologies was identified and combined approach in sizing process to consider the interrelationship among engine, rotor and blade duct was introduced.

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THE PRESSURE-TRANSIENT ANALYSIS ON THE PLATFORM SCREEN DOORS OF THE SIDE PLATFORMS IN A SUBWAY STATION WITH VARIOUS OPERATING CONDITIONS (열차 운행에 따른 상대식 승강장에서 지하철 승강장 스크린 도어 풍압해석)

  • Lee, Myung-Sung;Ahn, Hyuk-Jin;Won, Chan-Shik;Hur, Nahm-Keon
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03a
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    • pp.283-289
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    • 2008
  • The pressure-transient on platform screen doors in side platforms caused by passing trains with various operating conditions have been investigated numerically. The transient compressible three-dimensional flow simulations are performed with actual operating conditions of two trains by adopting moving mesh technique. To achieve more realistic results, the detailed shape of train and the subway station including tunnels connecting the adjacent stations are represented in the computational domain. Numerical analyses are carried out for cases considering arriving/passing/departing train with or without train stopped on the opposite track, and both trains on the move in opposite direction. From the numerical results, the maximum pressure on the platform screen doors, which is predicted in the case of two passing trains, satisfied the design standards for similar stations.

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THE PRESSURE-TRANSIENT ANALYSIS ON THE PLATFORM SCREEN DOORS OF THE SIDE PLATFORMS IN A SUBWAY STATION WITH VARIOUS OPERATING CONDITIONS (열차 운행에 따른 상대식 승강장에서 지하철 승강장 스크린 도어 풍압해석)

  • Lee, Myung-Sung;Ahn, Hyuk-Jin;Won, Chan-Shik;Hur, Nahm-Keon
    • 한국전산유체공학회:학술대회논문집
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    • 2008.10a
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    • pp.283-289
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    • 2008
  • The pressure-transient on platform screen doors in side platforms caused by passing trains with various operating conditions have been investigated numerically. The transient compressible three-dimensional flow simulations are performed with actual operating conditions of two trains by adopting moving mesh technique. To achieve more realistic results, the detailed shape of train and the subway station including tunnels connecting the adjacent stations are represented in the computational domain. Numerical analyses are carried out for cases considering arriving/passing/departing train with or without train stopped on the opposite track, and both trains on the move in opposite direction. From the numerical results, the maximum pressure on the platform screen doors, which is predicted in the case of two passing trains, satisfied the design standards for similar stations.

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Partially Folded States of Mutant Ubiquitin in Mild Denaturing Conditions

  • Park, Soon-Ho
    • Bulletin of the Korean Chemical Society
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    • v.30 no.7
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    • pp.1567-1572
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    • 2009
  • Conformational change of ubiquitin variant with valine to alanine mutation at sequence position 26 was studied by varying solvent pH. Fluorescence emission spectra indicated that this variant ubiquitin has some residual structures in acidic and basic solution as compared to denaturant-induced unfolded state. Far-UV circular dichroic spectra indicated that the base-denatured state had more secondary structure than the acid-denatured state. Near-UV circular dichroic spectra indicated that the aromatic side-chains were in the relatively more rigid environment in the base-denatured state than those in the acid-denatured state. Although it appears that the more tertiary structure present in the base-denatured state, refolding reactions measured by stopped-flow fluorescence device suggest that both the acid- and base-denatured states occur before the major folding transition state. The acid- and base-denatured states are considered to reflect the early event of protein folding process.

Kinetic Approaches to Measuring Peroxiredoxin Reactivity

  • Winterbourn, Christine C.;Peskin, Alexander V.
    • Molecules and Cells
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    • v.39 no.1
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    • pp.26-30
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    • 2016
  • Peroxiredoxins are ubiquitous thiol proteins that catalyse the breakdown of peroxides and regulate redox activity in the cell. Kinetic analysis of their reactions is required in order to identify substrate preferences, to understand how molecular structure affects activity and to establish their physiological functions. Various approaches can be taken, including the measurement of rates of individual steps in the reaction pathway by stopped flow or competitive kinetics, classical enzymatic analysis and measurement of peroxidase activity. Each methodology has its strengths and they can often give complementary information. However, it is important to understand the experimental conditions of the assay so as to interpret correctly what parameter is being measured. This brief review discusses different kinetic approaches and the information that can be obtained from them.

Kinetic Studies on the Reaction of Iron (Ⅲ) with D-penicillamine in Acidic Solution$^1$

  • Hyun-Jae Park;Yung-Hee Oh Kim;Jung-Ae Shim;Sung-Nak Choi
    • Bulletin of the Korean Chemical Society
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    • v.14 no.4
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    • pp.444-449
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    • 1993
  • Anaerobic oxidation of D-penicillamine by Fe(III) in acidic solution has been studied kinetically by the use of stopped-flow system. The reaction is biphasic with a rapid complexation of 1: 1 complex, $Fepen^+$ (pen= D-penicillamine dianion) which is then internally reduced to Fe(II) and disulfide. Rates of both the complexation and the redox process are pH dependent and also are affected by the presence of chloride ion. Different from the reaction of Cu(II) with D-penicillamine, partially oxidized mixed-valence complex is not formed even transiently in this reaction.