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기상 증착된 비정질 실리콘 카바이드 박막질의 기판 온도 의존성
김주영,이백우,남호석,권동일 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.3
The dramatic variations in structure and internal stress in an amorphous silicon carbide film (a-SiC) induced by forming process have been reported extensively. Vapor-depositions of a-SiC film were simulated by molecular dynamics simulation employing the Tersoff potential. To understand effect of substrate temperature that is one of the most important factors involved in the changes in structure and intrinsic stress, the vapor-depositions at various substrate temperatures (500-2500 K) were performed. Then, the MD simulations of cooling to 298 K were carried out. For both cooled and as-deposited a-SiC films, the analyses of structure and internal stress with deposition process parameters entailed the calculation of density, chemical order, and in-plane stress [(σ_(xx)+σ_(yy))/2].
Ho, Dongil,Vegiraju, Sureshraju,Choi, Donghee,Cho, Chang-Hui,Kwon, Guhyun,Huang, Po-Chun,Lee, Gene-Hsiang,Earmme, Taeshik,Yau, Shueh Lin,Chen, Ming-Chou,Kim, Choongik Elsevier 2019 Dyes and pigments Vol.163 No.-
<P><B>Abstract</B></P> <P>Solution-processable thioalkylated bithiophene derivatives with different lengths of side chains (<B>SBT-n</B>; <B>n</B> = <B>10</B>, <B>12</B>, <B>14</B>, <B>16</B>, <B>18</B>) have been synthesized and characterized as p-channel organic semiconductors for thin-film transistors (TFTs). Based on a combination of the highest performing SBT derivative (<B>SBT-14</B>) and quinoidals (<B>DTTRQ</B>s) as p- and n-channel materials, solution-processed small-molecular bulk heterojunction (BHJ) ambipolar thin-film transistors were fabricated, and the resulting devices showed air-stable and high ambipolar performance with well-balanced electron and hole mobilities as high as 0.70 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> and 0.21 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>, respectively. Furthermore, complementary-like inverters comprising two ambipolar thin-film transistors were demonstrated, which exhibited a high voltage gain of up to 81. Our study clearly demonstrated that side chain engineering of small molecular organic semiconductors had a significant influence on the electrical performance of TFTs and BHJ transistors, as well as complementary-like inverters.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Solution-processable thioalkylated bithiophene derivatives are synthesized. </LI> <LI> Ambipolar transistors are fabricated based on bulk heterojunction small molecules. </LI> <LI> High electrical performance with carrier mobilities of 0.21–0.70 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> is achieved. </LI> <LI> Complementary-like inverters based on bulk-heterojunction transistors show high transfer gain of 81. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Enhancing gas–liquid volumetric mass transfer coefficient
Dongil Ho,Kwangmin Kim,Taeshik Earmme,Choongik Kim 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.87 No.-
Methane-based biorefineries for biofuel production by microorganisms has gained interest due to theworldwide development of shale gas as an alternative source for fossil fuels. For the practical applicationof biological conversion process to industrial scale, enhancement of the gas–liquid volumetric masstransfer coefficient (kLa) in a gas diffusing system is crucial. This review article provides an overview ofthe developments on gas–liquid volumetric mass transfer enhancement through increasing the gas–liquid mass transfer coefficient term ‘kL’ and/or increasing the gas–liquid interfacial area term ‘a’. Twomajor enhancement methods which are summarized and discussed here include the most recentaccomplishments in gas–liquid mass transfer engineering of gas diffusing systems. The most up-to-datemechanical modification of reactor and additive employment rationales and discussions providing astrong understanding of gas–liquid volumetric mass transfer relationships are presented. Thus, thisreview is expected to inspire new research for future developments and applications in gas–liquid masstransfer engineering for gas diffusing systems.
표면균열이 있는 직관에 대한 선형탄성 응력확대계수 유한요소해석 결과의 요소 및 균열형상 민감도
류동일(Dongil Ryu),배경동(Kyung-Dong Bae),제진호(Jin-Ho Je),안중혁(Joong-Hyok An),김윤재(Yun-Jae Kim),송태광(Tae-Kwang Song),김용범(Yong-Beum Kim) 대한기계학회 2013 大韓機械學會論文集A Vol.37 No.4
본 논문에서는 3 차원 유한요소해석을 통해 표면균열이 있는 직관에 내압, 굽힘, 그리고 비틀림의 단일 또는 복합하중이 작용하는 경우의 응력확대계수를 연구하였다. 두 가지 결함평가코드(API-579-1, RCC-MR A16)를 각각 유한요소해석 결과와 비교하여 코드 간의 차이 및 해석의 신뢰성을 확인하였다. 응력확대계수는 적분 경로에 독립적이기 때문에 민감하지 않다고 알려져 있는데 3 차원 유한요소해석을 통해 요소 수에 대한 민감도를 확인하였다. 또한 균열형상의 정의방법에 따른 유한요소해석 결과의 차이와 두 가지 결함평가코드를 사용한 결과의 차이를 확인하였다. This study provides the elastic stress intensity factors, K, for circumferential and longitudinal surface cracked straight pipes under single or combined loads of internal pressure, bending, and torsion based on three-dimensional (3D) finite element (FE) analyses. FE results are compared with two different types of defect assessment codes (API- 579-1 and RCC-MR A16) to prove the accuracy of the FE results and the differences between the codes. Through the 3D FE analysis, it is found that the stress intensity factors are sensitive to the number of elements, which they were believed to not be sensitive to because of path independence. Differences were also found between the FE analysis results for crack defining methods and the results obtained by two different types of defect assessment codes.
Three-Dimensional Fin-Structured Semiconducting Carbon Nanotube Network Transistor
Lee, Dongil,Lee, Byung-Hyun,Yoon, Jinsu,Ahn, Dae-Chul,Park, Jun-Young,Hur, Jae,Kim, Myung-Su,Jeon, Seung-Bae,Kang, Min-Ho,Kim, Kwanghee,Lim, Meehyun,Choi, Sung-Jin,Choi, Yang-Kyu American Chemical Society 2016 ACS NANO Vol.10 No.12
<P>Three-dimensional (3-D) fin-structured carbon nanotube field-effect transistors (CNT-FETs) with purified 99.9% semiconducting CNTs were demonstrated on a large scale 8 in. silicon wafer. The fabricated 3-D CNT-FETs take advantage of the 3-D geometry and exhibit enhanced electrostatic gate controllability and superior charge transport. A trigated structure surrounding the randomly networked single-walled CNT channel was formed on a fin-like 3-D silicon frame, and as a result, the effective packing density increased to almost 600 CNTs/mu m. Additionally, highly sensitive controllability of the threshold voltage (V-TH) was achieved using a thin back gate oxide in the same silicon frame to control power. consumption and enhance performance. Our results are expected to broaden the design margin of CNT-based circuit architectures for versatile applications. The proposed 3-D CNT-FETs can potentially provide a desirable alternative to silicon based nanoelectronics and a blueprint for furthering the practical use of emerging low-dimensional materials other than CNTs.</P>