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General SPICE Modeling Procedure for Double-Gate Tunnel Field-Effect Transistors
Najam, Syed Faraz,Tan, Michael Loong Peng,Yu, Yun Seop The Korea Institute of Information and Commucation 2016 Journal of information and communication convergen Vol.14 No.2
Currently there is a lack of literature on SPICE-level models of double-gate (DG) tunnel field-effect transistors (TFETs). A DG TFET compact model is presented in this work that is used to develop a SPICE model for DG TFETs implemented with Verilog-A language. The compact modeling approach presented in this work integrates several issues in previously published compact models including ambiguity about the use of tunneling parameters A<sub>k</sub> and B<sub>k</sub>, and the use of a universal equation for calculating the surface potential of DG TFETs in all regimes of operation to deliver a general SPICE modeling procedure for DG TFETs. The SPICE model of DG TFET captures the drain current-gate voltage (I<sub>ds</sub>-V<sub>gs</sub>) characteristics of DG TFET reasonably well and offers a definite computational advantage over TCAD. The general SPICE modeling procedure presented here could be used to develop SPICE models for any combination of structural parameters of DG TFETs.
Capacity Analysis for mmWave Communication Systems Based on 3D Spatial Propagation Models
Najam Us Saqib(사킵 나잠어스),Muhammad Sajid Haroon(무하마드 사지드 하룬),Hoon-Geun Song(송훈근),Sang-Woon Jeon(전상운) 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.6
We present the capacity analysis of the millimeter Wave (mmWave) systems in a realistic 3-dimensional spatial channel model (3D-SCM) provided by the third-generation partnership project (3GPP). With the consideration of analog elevation beamforming in 3D Urban Micro Streat Canyon (UMi-Street Canyon) environment, capacity comparisons are performed considering mmWave frequencies. In particular, several factors such as rand and gas losses are analyzed, which have significant effects on channel capacity for high frequency communications.
Najam ul Hassan,Yoon-Jae Kim,Byung-Moon Han,Jun-Young Lee 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.1
This paper proposes a dc/dc converter for electric vehicle onboard chargers using a secondary resonant tank. To attain soft switching characteristics, such as zero voltage switching, magnetizing inductance has been used at the primary side of the transformer. The leakage inductance of the transformer is used as a resonant inductor on the secondary side to avoid the use of a separate inductor as resonance. The proposed converter is applicable for a wide load range. A 6.6KW prototype has been implemented for a wide range of load variations (250V, 330V, 360V, and 413V). A maximum efficiency of 97.4% is achieved at 413V.
Najam, Faraz,Kim, Sangsig,Yu, Yun Seop The Institute of Electronics and Information Engin 2013 Journal of semiconductor technology and science Vol.13 No.5
An explicit surface potential calculation method of gate-all-around MOSFET (GAAMOSFET) devices which takes into account both interface trap charge and varying doping levels is presented. The results of the method are extensively verified by numerical simulation. Results from the model are used to find qualitative and quantitative effect of interface trap charge on subthreshold slope (SS) of GAAMOSFET devices. Further, design constraints of GAAMOSFET devices with emphasis on the effect of interface trap charge on device SS performance are investigated.
Torrefaction and Hydrothermal Carbonization (HTC) of Dead Leaves
Najam Ul Saqib,박성규,이재영 한국지하수토양환경학회 2014 지하수토양환경 Vol.19 No.5
Torrefaction and hydrothermal carbonization (HTC) are productive methods to reclaim energy from lignocellulosicbiomass. The hydrophobic, homogenized, energy dense and carbon rich solid fuel can be obtain from torrefaction andhydrothermal carbonization. Dead leaves were carbonized in a stainless steel reactor of volume 200 ml with torrefaction(250-270oC) for 120 minutes and hydrothermal carbonization (200-250oC) for 30 minutes, with mass yield solid fuelranging from 57-70% and energy content from 16.81MJ/kg to 22.01 MJ/kg compare to the biomass. The char producedfrom torrefaction process possess high energy content than hydrothermal carbonization. The highest energy yield of89.96% was obtained by torrefaction at 250oC. The energy densification ratio fluctuated in between 1.15 to 1.30. On thebasis of pore size distribution of the chars, the definition of the International Union of Pure and Applied Chemistry(IUPAC) was used as a classification standard. The pore diameter was ranging within 11.09-19 nm which play importantrole in water holding capacity in soil. Larger pores can hold water and provide passage for small pores. Therefore, it canbe concluded that high pore size char can be obtained my HTC process and high energy content char of 22.01 MJ/Kg with34.04% increase in energy can be obtain by torrefaction process.
Sum Rate Analysis of the Array of Subarrays Structures for mmWave Systems
Najam Us Saqib,Sang-Woon Jeon(전상운) 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.11
We consider the array structure to improve data rates for millimeter wave communication systems. Particularly, by fully utilizing the array of subarrays (AOSA) structure, we perform extensive simulation with various subarray sizes in the AOSA to examine their effects for urban micro scenarios. It is shown that the vertical stacking of subarrays outperforms other combinations with a fixed tilt angle. The sum rate performance is also analyzed based on the number of radio frequency chains among different frequencies.
Hassan, Najam ul,Kim, Yoon-Jae,Han, Byung-Moon,Lee, Jun-Young The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.1
This paper proposes a dc/dc converter for electric vehicle onboard chargers using a secondary resonant tank. To attain soft switching characteristics, such as zero voltage switching, magnetizing inductance has been used at the primary side of the transformer. The leakage inductance of the transformer is used as a resonant inductor on the secondary side to avoid the use of a separate inductor as resonance. The proposed converter is applicable for a wide load range. A 6.6KW prototype has been implemented for a wide range of load variations (250V, 330V, 360V, and 413V). A maximum efficiency of 97.4% is achieved at 413V.
Torrefaction and Hydrothermal Carbonization (HTC) of Dead Leaves
Saqib, Najam Ul,Park, Seong-Kyu,Lee, Jai-Young Korean Society of Soil and Groundwater Environment 2014 지하수토양환경 Vol.19 No.5
Torrefaction and hydrothermal carbonization (HTC) are productive methods to reclaim energy from lignocellulosic biomass. The hydrophobic, homogenized, energy dense and carbon rich solid fuel can be obtain from torrefaction and hydrothermal carbonization. Dead leaves were carbonized in a stainless steel reactor of volume 200 ml with torrefaction ($250-270^{\circ}C$) for 120 minutes and hydrothermal carbonization ($200-250^{\circ}C$) for 30 minutes, with mass yield solid fuel ranging from 57-70% and energy content from 16.81MJ/kg to 22.01 MJ/kg compare to the biomass. The char produced from torrefaction process possess high energy content than hydrothermal carbonization. The highest energy yield of 89.96% was obtained by torrefaction at $250^{\circ}C$. The energy densification ratio fluctuated in between 1.15 to 1.30. On the basis of pore size distribution of the chars, the definition of the International Union of Pure and Applied Chemistry (IUPAC) was used as a classification standard. The pore diameter was ranging within 11.09-19 nm which play important role in water holding capacity in soil. Larger pores can hold water and provide passage for small pores. Therefore, it can be concluded that high pore size char can be obtained my HTC process and high energy content char of 22.01 MJ/Kg with 34.04% increase in energy can be obtain by torrefaction process.