Equivalent-Circuit Analysis of Organic Light-Emitting Diodes byUsing the Frequency-Dependent Response of an ITO/Alq3/Al Device

Jamil Muhammad,J.T. Rhee 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.2

We used the frequency-dependent response of an ITO/Alq3(60 nm)/Al device at two different bias voltages to perform an equivalent-circuit analysis of organic light-emitting diodes. The complex impedance Z of the device was measured in the frequency range of 40 Hz 1 MHz. A Cole-Cole plot showed that there were two dielectric relaxations at a bias below the turn-on voltage and one relaxation at a bias above the turn-on voltage. We were able to interpret the frequency-dependent response in terms of the equivalent-circuit model of a contact resistance Rs in series with a parallel combination of a resistance Rp and a capacitance Cp. We obtained a contact resistance Rs of around 90 , mainly from the ITO anode.

Simulation Response of a Multi-Gap Resistive Plate Chamber to Gamma-rays of 0.007 MeV < Er < 1.0 GeV

M. Jamil,J. T. Rhee,H. Jhang,전영재 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.1

This paper describes the simulation performance of a multigap resistive plate chamber(RPC). This work reports GEANT4 based simulation results for a multigap RPC obtained for gamma rays in the energy range 0.007 MeV - 1.0 GeV. These simulation results show that the gamma- ray sensitivity (for an isotropic source) in the 3-gap model is 5.52 ×10^-2 at about 1.0 GeV. For the same energy scale and source configuration, with the 4-gaps model, this results is 5.54 × 10^-2. Similar, but lower sensitivity results, have been found for the parallel gamma- source configurations. A comparison of previous results for single- and multi-gap RPC with the current simulation results is performed.

New GEANT4 Monte Carlo Simulation Results of a Multigap RPC for Positrons and Electrons

M. Jamil,J. T. Rhee,Young Jae Jeon 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.4

GEANT4 Monte Carlo simulations are a useful tool to evaluate different particle responses for various experimental environments. By employing the GEANT4 toolkit, one can take into account many detector characteristics. In this work, a multigap resistive plate chamber (MRPC) has been simulated using the GEANT4 Monte Carlo code to study the response of charged particles, and in particular electrons and positrons. As a comparison test, relatively different MRPC configurations single-gap, 3-gap, 5-gap, and 7-gap configurations, have been used to measure the performance of the MRPC. By employing the GEANT4 MC code, both e+ and e− were inserted into the MRPC chambers in the energy range of 0.1 – 100 MeV. A summary of the obtained results is presented. GEANT4 Monte Carlo simulations are a useful tool to evaluate different particle responses for various experimental environments. By employing the GEANT4 toolkit, one can take into account many detector characteristics. In this work, a multigap resistive plate chamber (MRPC) has been simulated using the GEANT4 Monte Carlo code to study the response of charged particles, and in particular electrons and positrons. As a comparison test, relatively different MRPC configurations single-gap, 3-gap, 5-gap, and 7-gap configurations, have been used to measure the performance of the MRPC. By employing the GEANT4 MC code, both e+ and e− were inserted into the MRPC chambers in the energy range of 0.1 – 100 MeV. A summary of the obtained results is presented.

The Revival Role of Nuclear Emulsion Chamber in OPERA Experiment

( J. T. Rhee ),( S. Y. Jung ),( M. Jamil ),( H. Jhang ) 건국대학교 기초과학연구소 2005 理學論集 Vol.30 No.-

We discuss about nuclear emulsion detector, its, history, types, scanning techniques as well as its key role in OPERA experiment. Nuclear emulsion can be considered as analog data storage device from which the automatic scanning system retrieves the data stored in it. The recent improvement of emulsion scanning techniques brings back these nuclear emulsion as one of the most important detectors among all other elementary particle detectors. OPERA uses the emulsion cloud chamber (ECC) technique, which was used previously by the DONUT experiment. As in the OPERA experiment good modularity for large apparatus, the existence of automatic scanning system and availability of fast data scan (Net Scan) are the required parameters, which can only be obtained by utilizing the ECC Nuclear emulsion technique. Therefore, the role of nuclear emulsion is very important in the OPERA experiment.

Monte Carlo Simulation of the Response to Fast Neutrons of a Multi-gap RPC (MRPC) by Using the GEANT4 Code

J. T. Rhee,조현용,M. Jamil,전영재 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.7

This article reports the simulated response to fast neutrons of a multi-gap resistive plate chamber (MRPC) by using the GEANT4 MC code. In this study, a thin polyethylene layer, which acted as the converter material for the detection of fast neutrons, was coated on the surface of the MRPC, which acts as the converter material for the detection of fast neutrons. The converter based on the polyethylene material improved the chamber’s ability to detect fast neutrons. By employing the GEANT4 MC code, fast neutrons were inserted into the converter-based MRPC chamber in the energy range of 1.0–20.0 MeV. The response of the polyethylene-coated MRPC were evaluated as a function of the neutron energy by using the QGSP BERT HP and the QGSP_BIC_HP physics list with the GEANT4 code. For a 0.13-mm converter thickness, a detection efficiency of 6.4×10−3 were found for fast neutrons with an energy of En = 6.0 by the QGSP_BERT_HP physics list. The simulation test further confirmed that a higher response of the fast neutrons could be achieved if the converter thickness were to be increased. A detailed outline of the simulation test and the obtained results are presented.

Impact of Different Implant Surfaces Topographies on Peri-Implant Tissues: An Update of Current Available Data on Dental Implants Retrieved from Human Jaws

A. Shibli, Jamil,T. Pires, Jefferson,Piattelli, Adriano,Iezzi, Giovanna,Mangano, Carlo,Mangano, Francesco,L.S. de Souza, Sergio,A. Gehrke, Sergio,Wang, Hom-Lay,M. Dohan Ehrenfest, David Bentham Science Publishers Ltd. 2017 CURRENT PHARMACEUTICAL BIOTECHNOLOGY Vol. No.

Modeling and Forecasting Saudi Stock Market Volatility Using Wavelet Methods

Tariq S. ALSHAMMARI,Mohd T. ISMAIL,Sadam AL-WADI,Mohammad H. SALEH,Jamil J. JABER 한국유통과학회 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.11

This empirical research aims to modeling and improving the forecasting accuracy of the volatility pattern by employing the Saudi Arabia stock market (Tadawul)by studying daily closed price index data from October 2011 to December 2019 with a number of observations being 2048. In order to achieve significant results, this study employs many mathematical functions which are non-linear spectral model Maximum overlapping Discrete Wavelet Transform (MODWT) based on the best localized function (Bl14), autoregressive integrated moving average (ARIMA) model and generalized autoregressive conditional heteroskedasticity (GARCH) models. Therefore, the major findings of this study show that all the previous events during the mentioned period of time will be explained and a new forecasting model will be suggested by combining the best MODWT function (Bl14 function) and the fitted GARCH model. Therefore, the results show that the ability of MODWT in decomposition the stock market data, highlighting the significant events which have the most highly volatile data and improving the forecasting accuracy will be showed based on some mathematical criteria such as Mean Absolute Percentage Error (MAPE), Mean Absolute Scaled Error (MASE), Root Means Squared Error (RMSE), Akaike information criterion. These results will be implemented using MATLAB software and R- software.

Development and performance characteristics of silane crosslinked poly(vinyl alcohol)/chitosan membranes for reverse osmosis

M. Shafiq,A. Sabir,A. Islam,S.M. Khan,S.N. Hussain,M.T.Z. Z. Butt,T. Jamil 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.48 No.-

Novel thinfilm poly(vinyl alcohol)/chitosan (PVA/CS) based reverse osmosis membranes infused withsilane crosslinked tetraethylorthosilicate (TEOS) were prepared by dissolution casting methodology. Theperformance characteristics and the scope of the reverse osmosis membranes were explicated by Fouriertransform infrared spectroscopy (FTIR), thermogravimetric analyzer (TGA), differential scanningcalorimetery (DSC), scanning electron microscopy (SEM), contact angle, X-ray diffraction (XRD) andreverse osmosis (RO) permeation tests which determined the functional groups and network of covalentcrosslinks, thermal properties, morphology, hydrophilicity, structural investigation and RO properties,respectively. It was found that the membrane surface became smoother, more hydrophilic, withimproved thermal stability, increased salt rejection and good permeationflux after the appropriateinfusion of TEOS. The crosslinked membranes showed more hydrophilicity compared to theuncrosslinked PVCS membrane. The SEM micrographs of membranes revealed dense structure withno mottled surfaces. PVCS-4 showed an optimalflux of 1.84 L/m2h and 80% salt rejection that confirmedthe selective interaction of TEOS molecules with PVA/CS polymer backbone compared to the pristine(PVCS) membrane. The antibacterial properties of the membranes showed the inhibition of the growth ofEscherichia coli successfully.

Structure-based magnetic, electrical and transport properties of Ni–Zn–Co ferrite by V5+ substitution

Hossain M.D.,Khan M.N.I.,Hossain Md Sarowar,Ahned S.J.,Alam M.K.,Liba S.I.,Hakim M.A.,Jamil A.T.M.K. 한국물리학회 2022 Current Applied Physics Vol.43 No.-

This article presents the modification of structure-based magnetic, electronic and transport properties along with the conduction mechanism and its relaxation process in a Ni–Zn–Co ferrite tailored by V5+ substitution at B-site replacing Fe3+ ions. The composition Ni0.7Zn0.2Co0.1Fe2-xVxO4 (0≤ x≤ 0.12) was synthesized by standard solid-state reaction method and all samples were crystallized with a single-phase cubic spinel structure belonging to the Fd3m space group. The lattice constants decreased gradually from 8.3673≽A to 8.3602≽A and the average grain sizes (DSEM) are also decreased from 6.92 μm to 1.99 μm due to V5+ ions substitution at Fe3+ of B-site. However, more than 25% of Fe3+ ions migrate to A-site from B-site due to V5+ substitution at Fe3+ of B-site. In all samples θD does not strictly follow the Anderson’s prediction, rather it monotonically decreases to a low value until x = 0.12. Magnetic phase transition temperature shifted to the lower temperature and the net magnetization (ηeB) decreases due to V5+ substitution in Ni–Zn–Co ferrite. Apart this, during conduction charge carriers should require more energy to jump from one cationic site to other for V5+ substitution in the Ni–Zn–Co ferrite and the activation energy (Ea) is much more higher in V5+ substituted sample. Moreover, long-range interaction with localized relaxation mechanism is observed in V5+ doped samples. The resistance at the grain (Rg) is maximum (243.09 Ω) for the sample x = 0.10 while grain boundary resistance (Rgb) is maximum (5.98×105 Ω) for the sample x = 0.07. However, the higher value of ρdC for x = 0.12 sample ensures to be suitable for electromagnets, transformers, electronic inductors, and at high-frequency applications. Moreover, x = 0.07 sample displays high value of TCR ( -8.6%/K at 418 K) which may be utilized as an infrared detector for night vision bolometer material.