노지감귤과 스마트팜의 비용분석 : 몬테카를로 시뮬레이션 활용

오현곤 제주대학교 대학원 2022 국내석사

The purpose of this study is to investigate the difference in Management expenses between smart farms and outdoor mandarin through Monte Carlo simulation. Monte Carlo simulation was performed through Oracle Ball. Tornado analysis, Spider chart, sensitivity analysis, Predictor analysis, and predictive comparative analysis were performed using Oracle Ball. Recently, artificial intelligence, augmented reality, and big data have become common, while agriculture is aging severely. Agriculture is threatened with sustainability due to a decrease in the labor force. Smart farms are being distributed to solve the aging problem of agriculture. Smart Farm has the advantage of reducing working hours and increasing production. However, uncertainty is often linked between technology and technology users. This uncertainty is solved through simulation. In Tornado and Spider chart analysis, pesticide costs, fertilizer costs, and site development cost have a great influence on intermediate goods. In sensitivity analysis, pesticide costs, redemption cost for farming facilities, and fertilizer costs have a great influence on intermediate goods. In the predictive simulation analysis, it was analyzed that there was no significant difference between smart farms and outdoor mandarin of intermediate goods. This was analyzed because there was no significant difference in pesticide costs, which have a great influence on intermediate goods.

인공사를 이용한 알루미늄 주조용 세라믹 바인더의 물리화학적 특성에 관한 연구

오현곤 부산대학교 대학원 2020 국내석사

주조 산업에서, Al2O3-SiO2로 구성된 뮬라이트 (mullite) 계열의 인공사는 자동차, 조선, 기계 및 화학 산업에서 복잡한 형상의 부품 또는 사형 중자 제조를 위해 많은 연구가 이루어지고 있다. 구상의 인공사는 내파쇄성 및 내구성이 우수하여 미분 발생량이 규사에 비해 적다. 바인더에는 유기 바인더와 무기 바인더로 분류되며 사형 주조 시 유기 바인더에서 배출되는 휘발성 유기화합물은 대기오염에 영향을 미친다. 이러한 문제를 해결하기 위해 인공사와 무기 바인더가 주목받고 있는 소재이다. 다양한 무기 바인더 중 CBAPC (chemically bonded aluminum phosphate ceramic) 바인더는 고온에서의 우수한 내열성, 내식성 및 강도를 가지는 친환경 소재이다. 본 연구에서는 인공사를 이용한 CBAPC 기반의 무기 바인더를 개발하였다. CBAPC 바인더는 2.0에서 6.0까지의 다양한 P/Al 몰 비로 합성되었다. 인공사 및 CBAPC 바인더를 혼합하여 시험편을 제조하였으며, 260 ℃에서 10분간 열처리하였다. P/Al 몰 비, 경화 온도 및 경화 시간에 따른 시험편의 항절 강도를 확인하였다. 인공사 (Esperal 40, Cps 1)는 XRF, 입자 크기 및 FE-SEM으로 특성 분석하였으며, 제조된 CBAPC 바인더는 TGA-DSC, XRD, FT-IR 및 FE-SEM에 의해 특성 분석하였다. 인공사 (Esperal 40, Cps 1)의 최대 항절 강도는 P/Al 몰 비가 4.5, 경화온도 260 ℃ 및 경화 시간 10분 조건에서 각각 6.40 및 6.36 MPa를 나타내었다. CBAPC_4.5는 다른 P/Al 몰 비보다 저온 구간에서 높은 열 안정성을 가졌으며 260 ℃에서 형성된 AlH2P3O10·2H2O 상은 높은 기계적 강도 및 내습성을 가진다. CBAPC_4.5로 코팅된 인공사의 표면은 경화 온도 및 경화 시간에 따라 영향을 받았다. 따라서, P/Al 몰 비 및 경화 조건이 항절 강도에 큰 영향을 미치는 것을 확인하였다. In foundry industry, mullite-based artificial sand composed of Al2O3-SiO2 is being studied to manufacture complex shaped parts and sand cores in the automobile, shipbuilding, machinery, and chemical industry. The spherical artificial sands were superior fracture resistance and durability, so the amount of fine dust is smaller than silica sand. Binders were classified into organic binder and inorganic binder, the volatile organic compounds emission from organic binder during sand casting process strongly contributes to air pollution. In order to solve these problems, artificial sand and inorganic binder receive attention as materials. CBAPC (chemically bonded aluminum phosphate ceramic) binders are an eco-friendly material with outstanding heat resistance, corrosion resistance, and strength at high temperature. In this study, we developed an inorganic binder based on CBAPC binder using artificial sand for casting. The CBAPC binders were synthesized for various P/Al molar ratios from 2.0 to 6.0. The specimens were prepared by mixing artificial sand and CBAPC binder, which is heat-treated at 260 ℃ for 10 min. The flexural strength of the specimens was observed according to the P/Al molar ratio, curing temperature, and curing time. The artificial sands (Esperal 40, Cps 1) were characterized by XRF, grain size analysis, and FE-SEM, and the prepared CBAPC binders were characterized by TGA-DSC, XRD, FT-IR, and FE-SEM. The ultimate flexural strengths of artificial sands (Esperal 40, Cps 1) were obtained 6.40 and 6.36 MPa, respectively under the conditions (P/Al=4.5, curing temperature=260 ℃, and curing time=10 min.). The CBAPC_4.5 had higher thermal stability at low temperature than other P/Al molar ratio. The formed AlH2P3O10·2H2O structure at 260 ℃ having high mechanical strength and moisture resistance affected to improvement of flexural strength. The surfaces of CBAPC_4.5 coated artificial sands were affected depending on the curing temperature and curing time. Thus, we confirmed that P/Al molar ratio and curing conditions strongly affect to flexural strength.

Saddle MOSFET의 Self-Heating 특성에 대한 열 분석 연구

오현곤 명지대학교 대학원 2014 국내석사

Silicon-based Metal Oxide-Silicon-Field-Effect-Transistor(MOSFET)s have been successfully scaled down with surprising velocity in the past decades. However, the short channel effects(SCE) of device have increased as scaling down progressed. To overcome SCEs on MOSFETs, 3D structure field effect transistors (FETs), such as FinFETs and saddle MOSFETs have been attracted growing interests as possible device structures beyond 30 nm and various modeling and analysis were investigated with previous works. The Saddle MOSFET including advantage of RCAT and having the similar structure as FinFET was previously introduced. Saddle MOSFET has advantage such as excellent SCE immunity, high DIBL, excellent subthreshold swing(SS), nearly constant Vth with the recess depth ,and large process margin over conventional RCAT. Recently, results from multiple research about thermal analysis of transistors were already published by many research groups. The temperature rise causes a decrease in the drain current and leads to more serious reliability problems such as increased electro-migration and enhanced impact ionization. In the past, several attempts have been made to reduce the temperature rise stemming from this self-heating.[8] So the thermal analysis of semiconductor devices, such as FinFET, MOSFET and etc, have been studied through the electro-thermal simulation. In this paper we investigate electro-thermal simulations of Saddle MOSFET. In addition, the variation of gate overlap side length is studied by using combined simulation method with device simulator and finite element analysis simulation. From the above results, Lov_side determines heat transfer characteristics of saddle device. Since it also determines important electrical characteristics such as SS and threshold voltage, optimization of Lov_side should be carefully considered to meet the device specifications. In this work, thermal analysis of Saddle MOSFET for high performance and reliability is investigated with electrical and thermal simulation. 지난 30년 동안 Microelectronics 분야를 주도해 온 실리콘 소자 기술은 Moore의 법칙에 따른 지속적인 소자의 소형화를 통하여 집적도 향상 및 소자의 성능 개선 방향으로 발달해 왔다. 실리콘 소자의 크기가 nanoscale 크기로 감소하면서 실리콘 소자에 발생하는 Short Channel 효과를 획기적으로 줄일 수 있는 이중게이트(Double-Gate), FinFET, Recess Channel MOSFET, Saddle MOSFET과 같은 소자들이 대안으로 제시되었다. 또한 Substrate에 발생하는 누설전류를 제어하기 위해 Silicon On Insulator(SOI) 구조를 적용시키는 방안도 제시되었다. 이 중 Saddle MOSFET은 FinFET의 장점인 Gate controllability 향상과 Recess Channel MOSFET의 장점인 Effective Channel length 증가를 동시에 얻을 수 있는 소자로 개발되었다. 최근에는 Short Channel 효과 뿐만 아니라 소자에서 동작하면서 전류에 의해 발생하는 Self-Heating에 대한 관심이 높아졌다. Self-Heating 영향은 전기적인 기능과 반도체 소자의 성능에 직접적인 관여를 하지 않지만 chip의 신뢰성에 부정적인 영향을 미치게 된다. 본 연구에서는 Saddle MOSFET의 gate overlap length에 따른 전기적인 특성과 열 특성을 분석하기 위해 Electro-thermal modeling을 진행하였다. Electrical modeling은 Electrical 시뮬레이션 tool인 3D Silvaco Atlas를 활용하여 thermal 시뮬레이션에 필요한 물성치를 추출하는 작업을 진행하였고, Electro-thermal modeling은 Finite Element Method(FEM) 시뮬레이션 tool인 Ansys를 사용하여 modeling을 진행하여 열 특성을 분석하였다. Saddle MOSFET의 gate overlap length가 증가할 때 Subthreshold Swing 향상과 ON current 증가를 확인하였다. Self-Heating 특성 분석으로는 Saddle MOSFET이 동작하게 되면 channel에서 발생한 열이 thermal conductivity가 낮은 silicon 물질로 구성된 substrate쪽으로 heat sink가 일어나게 되는데 Saddle MOSFET의 gate overlap length가 증가하게 되면 substrate의 thermal resistance 값이 커지기 때문에 온도가 증가하는 것을 확인 할 수 있었다.

Fabrication and characterization of bendable thin film transistors with a-Si:H and a-IGZO channels

오현곤 Korea University 2018 국내박사

In this thesis, the bendable thin film transistors (TFTs) with hydrogenated amorphous silicon (a-Si:H) and amorphous indium gallium zinc oxide (a-IGZO) channels were fabricated on the plastic substrate and their mechanical and electrical characteristics under bending strain were investigated through experiment and simulation. In chapter 1, fundamental theories of bendable TFTs with a-Si:H and a-IGZO channels and the failure mechanism to mechanical strain were introduced. In chapter 2, experimental procedures for the fabrication of the bendable TFTs with a-Si:H and a-IGZO channels were described in detail. In chapter 3, the influence of overlapped gate region and various channel widths on the electrical characteristics of the bendable a-Si:H TFTs under bending stress are investigated by the mechanical simulation. In addition, effect of physical densification on sub-gap density of states distribution in a-IGZO film and the electrical characteristics of bendable a-IGZO TFTs as function of bending radius are discussed. In conclusion, the electrical characteristics of bendable TFTs with a-Si:H and a-IGZO channels and the mechanical analysis of bending stress exhibited possibilities for application in the bendable electronics including displays.