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양자효과를 고려한 실리콘 나노선 트랜지스터의 채널 크기에 따른 전도 및 전하분포 특성 시뮬레이션
황민영,최창용,문경숙,구상모,Hwang, Min-Young,Choi, Chang-Yong,Moon, Kyoung-Sook,Koo, Sang-Mo 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.9
We report numerical simulations to investigate of the dependendce of the on/off current ratio and channel charge distributions in silicon nanowire (SiNW) field-effect transistors (FETs) on the channel width and thicknesses. In order to investigate the transport behavior in devices with different channel geometries, we have performed detailed two-dimensional simulations of SiNWFETs and control FETs with a fixed channel length L of $10\;{\mu}m$, but varying the channel width W from 5 nm to $5\;{\mu}m$, and thickness t from 10 nm to 30 nm. We have show that $Q_{ON}/Q_{OFF}$ drastically decreases (from $^{\sim}2.9{\times}10^4$ to $^{\sim}9.8{\times}10^3$) as the channel thickness increases (from 10 nm to 30 nm). As a result of the simulation using a quantum model, even higher charge density in the bottom of SiNW channel was observed then in the bottom of control channel.
AFM을 이용한 나노 패턴 형성과 크기에 따른 광특성 시뮬레이션
황민영,문경숙,구상모,Hwang, Min-Young,Moon, Kyoung-Sook,Koo, Sang-Mo 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.6
We report a top-down approach based on atomic force microscopy (AFM) local anodic oxidation for the fabrication of the nano-pattern field effect transistors (FETs). AFM anodic oxidation is relatively a simple process in atmosphere at room temperature but it still can result in patterns with a high spatial resolution, and compatibility with conventional silicon CMOS process. In this work, we study nano-pattern FETs for various cross-bar distance value D, from ${\sim}0.5\;{\mu}m$ to $1\;{\mu}m$. We compare the optical characteristics of the patterned FETs and of the reference FETs based on both 2-dimensional simulation and experimental results for the wavelength from 100 nm to 900 nm. The simulated the drain current of the nano-patterned FETs shows significantly higher value incident the reference FETs from ${\sim}1.7\;{\times}\;10^{-6}A$ to ${\sim}2.3\;{\times}\;10^{-6}A$ in the infrared range. The fabricated surface texturing of photo-transistors may be applied for high-efficiency photovoltaic devices.
황민영,김용균,전충환,송주헌,김용태,장윤한,Hwang, Min-Young,Kim, Yong-Gyun,Jeon, Chung-Hwan,Song, Ju-Hun,Kim, Yong-Tae,Chang, Youn-Han 한국전기화학회 2009 한국전기화학회지 Vol.12 No.2
리튬 2차전지는 휴대용 전자기기의 전원으로 사용되어 왔다. 최근 하이브리드 자동차, 전기자동차의 에너지 저장매체로써 적용으로 인해 시장 확대가 기대되고 있다. 양극 활물질은 리튬2차전지의 성능, 수명, 용량을 결정하는 물질이며, 급증하는 시장의 수요에 따라 양극 활물질을 대량으로 생산할 수 있는 기술을 개발하는 것이 시급하다. 본 연구에서 실제 양극 활물질($LiCoO_2$) 생산라인에서 가동 중인 소성로를 3D 모델링하였고, 수치적 해석을 통해 소성로 내부의 온도와 유동의 방향, 화학적 거동을 밝혀내었다. 결과로써, 생산량 증가로 인해 소성로에서 생성되는 $CO_2$ 농도가 증가하며 정체되는 지점을 확인하였고, TGA-DSC 실험을 통해 $CO_2$가 몰분율 15%이상에선 $LiCoO_2$의 적절한 형성에 영향을 주는 현상을 확인하였다. 또한 소성로의 형상변화와 공정조건의 변화를 통해 문제되는 $CO_2$를 원활히 배출할 수 있는 해결책을 제안하였다. Lithium secondary batteries have been widely used in the portable electric devices as power source. Recently it is expected that the realm of its applications expands to the markets such as energy storage medium of hybrid electric vehicle(HEV), electric vehicle(EV). Cathode active material is crucial in terms of performance, durability, capacity of lithium secondary batteries. It is urgent to develope the technology for mass production of cathode material to cope with the markets' demands in the near future. In this study, a calcination furnace running in real production line is modelled in 3D, and the thermal flow and gas flow after chemical reaction in the furnace is analyzed through numerical computations. Based on the results, it is shown that large volume of $CO_2$ gas is generated from chemical reaction. High concentration of $CO_2$ gas and it's stagnation is clearly found from the reactant containers in which the reaction occur to the bottom area of the furnace. It is also studied that 15% or more $CO_2$ mol fraction could affect to proper formation of $LiCoO_2$ through TGA-DSC analysis. The solutions to evacuate carbon dioxide from the furnace are suggested through the change of furnace design and operating condition as well.
황민영(Min Young Hwang),전충환(Chung Hwan Jeon),송주헌(Ju Hun Song),김규보(Gyu-Bo Kim),김승모(Seung Mo Kim),박명석(Myung Suk Park) 대한기계학회 2011 大韓機械學會論文集B Vol.35 No.9
석탄은 고정탄소분, 휘발분, 수분, 회로 구성되며, 연소시 회성분과 소량의 고정탄소분이 남게 된다. 석탄화력 발전소에서는 석탄연소 후 나오는 잔여물(고정탄소분, 회)를 통칭하여 석탄회 라고 부르고 있다. 현재 발전소에서는 정제회(LOI함량 6%미만)는 경량골재의 원료로 재활용해 수익을 창출하고 있으나, LOI함량이 높은 회는 재활용이 불가능해 땅에 매립하고 있다. 이에 따라 환경적인 부담금을 줄이고 정제회 판매의 수익을 올리기 위해 회성분의 LIO감량은 필수적이다. 본 연구에서는TGA(Thermo-gravime- tric analysis)와 DTF(Drop tube furnce) 실험을 통해 석탄과 석탄회 연소를 위한 실험적인 상수 값을 결정하였다. 500㎿급 표준화력발전 보일러를 모델링하고, 전산해석을 위해 격자를 형성시키고 적절한 해석 모델을 선정하였으며, 석탄회 재연소 시뮬레이션을 수행하여 석탄회 투입시 보일러 내부의 온도 및 유동을 모사하였다. 보일러 내부 석탄 입자와 회입자의 이동 궤적을 통해 가능한 높은 버너 위치에서 석탄회를 투입하는 것이 적절함을 나타내었다. 또한 실제 설치 가능한 D버너에서 6ton/h로 공급시에 기존의 보일러에 큰 영향을 주지 않으며 재연소 가능함을 알 수 있다. In thermal power generation companies, the recycling of refined ash (LOI < 6%) obtained from a PC-firing furnace is beneficial for the companies, e.g., it can be used for making lightweight aggregates. However, ash having a high LOI, which cannot be reused, is still buried in the ground. To obtain refined ash, the re-burning of high-LOI ash (LOI > 6%) in a PC-firing furnace can be an alternative. In this study, a numerical analysis was performed to demonstrate the effects of ash re-burning. An experimental constant value was decided by TGA (thermo-gravimetric analysis), and a DTF (drop-tube furnace) was used in the experiment for calculating the combustion of ash. On the basis of the trajectory of the moving particles of coal and ash, it was concluded that supplying ash near the burner, which is located high above the ground, is appropriate. On the basis of numerical results, it was concluded that an ash supply rate of 6 ton/h is suitable for combustion, without affecting the PC-firing boiler.
황민영(Hwang min young),이종우(Lee jong woo),김용균(Kim yong gyun),전상훈(Jeon Sang hun),장윤한(Chang youn-han),전충환(Jeon chung hwan) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Secondary batteries are uesd cell phone and notebook computer. Cathode active material for the secondary battery is processed in high temperature furnace. Optimizing design for furnace is important to get the best quality of the material. Numerical approach for analyzing the fluid flow in the furnace saves time and money in comparison with experimental method. In this study, a furnace modeled and the boundary conditions are set for CFD analysis. The characteristic of the fluid thermal flow is obtained.
황민영(Min Young Hwang),전충환(Chung Hwan Jeon),송주헌(Ju hun Song) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
Secondary batteries are used cell phone and notebook computer. Cathode active material for the secondary battery is processed in high temperature calcination furnace. Optimizing design for furnace is important to get the best quality of the material. Numerical approach for analyzing the fluid flow in the furnace saves time and money in comparison with experimental method. In this study, a furnace modeled and the boundary conditions are set for CFD analysis. Solver setting for chemical reaction, species transport and porosity are simplified. A characteristic of the fluid thermal flow, direction vector and generated CO₂ gas flow are obtained.
황민영(Min-young Hwang),김규보(Gyu-bo Kim),김승모(Seung-mo Kim),전충환(Chung-hwan Jeon) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.5
In thermal power generation companies, refined ash (LOI<6%) from pc firing furnace has bought benefit to the companies through recycling in such as making light weight aggregate. However ash having high LOI which is not able to reuse is still burying in the ground. To obtain refined ash, re-burning of high LOI ash(LOI>6%) in pc firing furnace can be an alternative. In this study, numerical analysis was performed to reveal the effect of ash re-burning. Based on the numerical results, 2%wt ash and 4% excess air condition is suitable for pc firing furnace as aspects of temperature and emission.