• Title/Summary/Keyword: Hole space

Search Result 384, Processing Time 0.03 seconds

Conduction mechanism in organic light-emitting diode in ITO/PEDOT/PSS/TPD/Alq$_3$/LiAl structure (ITO/PEDOT/PSS/TPD/Alq$_3$/LiAl 구조의 유기 발광 소자에서 전도 메카니즘)

  • 정동회;김상걸;정택균;오현석;이원재
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2002.07a
    • /
    • pp.198-201
    • /
    • 2002
  • We have studied the temperature dependence of current-voltage and luminance-voltage characteristics of Organic Light Emitting Diodes(OLEDs). The OLEDS are based on the molecular compounds, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD) as a hole transport, tris(8-hydroxyquinolinoline) aluminum(III) (Alq$_3$) as an electron transport, and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as a buffer layer. The current-voltage and luminance-voltage characteristics were measured in the temperature range of 10[K] and 300[K]. A conduction mechanism in OLEDs has been interpreted in terms of space-charge-limited current(SCLC) and tunneling mechanism.

  • PDF

Dual Contrast EPI by Use of a Key Hole Technique

  • Jung, Kwan-Jin
    • Proceedings of the KSMRM Conference
    • /
    • 2001.11a
    • /
    • pp.113-113
    • /
    • 2001
  • Purpose: In the gradient echo EPI the conventional T2*-weighted image is poor in signal as well distorted by the field inhomogeneity. By acquiring a proton density image in addition to th T2*-weighted image at the same scan, the fMRI processing can be improved. Method: The central region of the k space is acquired twice at different time points after th RF pulse while acquiring the other regions onc as described in Fig. 1. In Fig. 1 the segment numbers are chronological. Then, we can get two images of different contrast by interleaving th central region in the k space as done in the dua contrast FSE.

  • PDF

New Instabilities in Accretion Flows onto Black Holes

  • MOLTENI D.;FAUCI F.;GERARDI G.;BISIKALO D.;KUZNETSOV O.;ACHARYA K.;CHAKRABARTI S.
    • Journal of The Korean Astronomical Society
    • /
    • v.34 no.4
    • /
    • pp.247-249
    • /
    • 2001
  • The accretion disks are usually supposed symmetric to reflection on the Z=0 plane. Asymmetries in the flow are be ver-y small in the vicinity of the compact accretor. However their existence can have a important role in the case of subkeplerian accretion flows onto black holes. These flows lead to strong heating and even to the formation of shocks close to the centrifugal barrier. Large asymmetries are due to the development of the KH instability triggered by the small turbulences at the layer separating the incoming flow from the out coming shocked flow. The consequence of this phenomenon is the production of asymmetric outflows of matter and quasi periodic oscillations of the inner disk regions up and down the Z=0 plane.

  • PDF

Host Galaxies of Nearby Type I AGNs

  • Kim, Min-Jin;Ho, Luis;Peng, Chien;Barth, Aaron;Im, Myung-Shin
    • The Bulletin of The Korean Astronomical Society
    • /
    • v.36 no.2
    • /
    • pp.68.2-68.2
    • /
    • 2011
  • We present the detailed image decomposition of Hubble Space Telescope archival images for 235 nearby (z < 0.35) unobscured type 1 AGNs. It allows us to perform robust measurements of host galaxy properties and AGN luminosity contribution. We examine how the host properties correlate with AGN properties. Broad line type 1 and radio-loud AGNs are hosted preferentially by early type galaxies. Narrow line type 1 AGNs show a low fraction of tidal interaction, that might suggest the secular evolution may play an important role for triggering AGN activity, while the fraction of merging hosts is rather higher in luminous AGNs. We compare the nucleus luminosity and bulge luminosity and find that either our sample might have a smaller zero point in the M(BH)-L(bulge) relation (i.e. less massive black hole at a given bulge luminosity) relation compared to the normal galaxies or Eddington ratio of our sample could be systematically overestimated.

  • PDF

Experimental Study on the Flow Characteristic of a Confined Ppray (제한된 공간내 분무의 유동특성 실험)

  • 정선재;이상용
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.16 no.5
    • /
    • pp.1011-1018
    • /
    • 1992
  • A series of experiment has been performed on the spray characteristics in a cylindrical confined space with the injection pressure taken as a parameter. By using a single-hole patternator and the Malvern particle sizer, the spray mass flux, drop size and volume concentration distributions along the radial and axial directions were obtained ; the line-of- sight data by Malvern particle sizer have been converted to the ring-of-sight data by using the tomographical transformation techniqe. The experimental results show that, due to the restriction on the ambient gas entrainment by the wall boundary, the effective spray angle is increasing. The spray drops were measured to be smaller in the confined space because of a large number of floating small drops by recirculation of the gas phase and the breakup of large drops by the wall collision. Also the details on the flow behavior of the confined spray are discussed.

A Study on the TCAD Simulation to Predict the Latchup Immunity of High Energy Ion Implanted CMOS Twin Well Structures (고 에너지 이온 주입된 CMOS 쌍 우물 구조의 레치업 면역성 예측을 위한 TCAD 모의실험 연구)

  • 송한정;김종민;곽계달
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.13 no.2
    • /
    • pp.106-113
    • /
    • 2000
  • This study describes how a properly calibrated simulation method could be used to investigate the latchup immunity characteristics among the various high energy ion implanted CMOS twin well (retro-grade/BILLI/BL) structures. To obtain the accurate quantitative simulation analysis of retrograde well, a global tuning procedure and a set of grid specifications for simulation accuracy and computational efficiency are carried out. The latchup characteristics of BILLI and BL structures are well predicted by applying a calibrated simulation method for retrograde well. By exploring the potential contour, current flow lines, and electron/hole current densities at the holding condition, we have observed that the holding voltage of BL structure is more sensitive to the well design rule (p+to well edge space /n +to well edge space) than to the retrograde well itself.

  • PDF

Temperature Dependent Current-Voltage Characteristics of Organic Light-Emitting Diodes using TPD/$Alq_3$ (TPD/$Alq_3$를 이용한 유기 발광 소자의 온도에 따른 전압-전류 특성)

  • Han, Wone-Keun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2005.07a
    • /
    • pp.533-534
    • /
    • 2005
  • Temperature-dependent current-voltage characteristics of organic light-emitting diodes(OLEDs) were studied in a device structure of ITO/TPD/$Alq_3$/Al. The OLEDs were based on the molecular compounds, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-l,1'-diphenyl-4,4'-diamine(TPD) as a hole transport and tris(8-hydroxyquinoline) aluminum($Alq_3$) as an electron transport and emissive material. The current-voltage characteristics were measured in the temperature range of 10K and 300K. We analyzed an electrical conduction mechanism of the OLEDs using space-charge-limited current(SCLC) and Fowler-Nordheim tunneling.

  • PDF

Micro-mechanical Failure Prediction and Verification for Fiber Reinforced Composite Materials by Multi-scale Modeling Method (멀티스케일 모델링 기법을 이용한 섬유강화 복합재료의 미시역학적 파손예측 및 검증)

  • Kim, Myung-Jun;Park, Sung-Ho;Park, Jung-Sun;Lee, Woo-Il;Kim, Min-Sung
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.41 no.1
    • /
    • pp.17-24
    • /
    • 2013
  • In this paper, a micro-mechanical failure prediction program is developed based on SIFT (Strain Invariant Failure Theory) by using the multi-scale modeling method for fiber-reinforced composite materials. And the failure analysis are performed for open-hole composite laminate specimen in order to verify the developed program. First of all, the critical strain invariants are obtained through the tensile tests for three types of specimens. Also, the matrices of strain amplification factors are determined through the finite element analysis for micro-mechanical model, RVE (Representative Volume Element). Finally, the microscopic failure analysis is performed for the open-hole composite laminate specimen model by applying a failure load obtained from tensile test, and the predicted failure indices are evaluated for verification of the developed program.

Analysis of Residual Stresses Induced by Cold Expansion Using Finite Element Method (유한요소법을 이용한 홀 확장 잔류응력 해석)

  • Kim, Cheol;Yang, Won-Ho;Heo, Seong-Pil;Jeong, Gi-Hyeon
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.30 no.2
    • /
    • pp.46-51
    • /
    • 2002
  • Cold expansion of fastener holes is a mechanical process widely used in the aerospace industry. This treatment leads to an improvement of fatigue behavior due to the developed compressive residual stresses on the hole surface. The residual stress profile depends on the parameters of cold expansion, which are expanding rate, inserting direction of mandrel, material properties dtc. Despite its importance to aerospace industiries, little attention has been devoted to the accurate modeling of the process. In this paper, three-dimensional finite element simulations have been conducted for the cold expansion in an aluminium plate in order to predict the magnitude and distribution of the residual stress. To prove the results of FE analysis, the residual strain was measured by strain gage in cold expansion test. Maximum compressive residual stress could be increase about 7 percentage using the 2-step cold expansion method.

BLR Density Variations of the Seyfert 1 Galaxies NGC 4151 and NGC 5548 (Seyfert 1 은하 NGC 4151, NGC 5548의 BLR 밀도 변화)

  • Son, Dong-Hoon;Hyung, Siek
    • Journal of the Korean earth science society
    • /
    • v.25 no.6
    • /
    • pp.495-501
    • /
    • 2004
  • Using numerous ground-based or space-based telescopes by many astronomers, AGN spectroscopic monitoring campaigns have been carried out over many years to study the variability of continua and emission lines. We investigate the SWP IUE spectra of a large aperture configuration for the Seyfert 1 galaxies NGC 4151 and NGC 5548. We estimate the BLR electron number densities and their variation from the line ratios of C III] 1909 to Si III] 1892. With the ratios of C IV 1550 to C III] 1909 which give us the information on the ionization parameter of BLR, we try to find the physical conditions of the BLR and activities of he super massive black hole surroundings. The BLR density variations scale as 4 and 8 for NGC 4151 and NGC 5548, respectively. Based on the BLR size and C III] line profiles, we found both black hole masses as about $10^7$ $M_{\odot}$.