• 새물리
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• 제68권12호
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• pp.1364-1373
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• 2018

사람의 생각을 사람들이 인지할 수 있게 표현한 인문학적 기호를 물리학적 기호로 체계적으로 변환한다. 기호를 체계적으로 사용하는 언어의 개념 구조를 수학적 형식으로 정리하고, 합리적인 개인의 선택을 함수로 표현하는 효용을 도입하였다. 일관성을 도입하여 효용을 보편화하고, 언어의 개념구조와 호환되게 함수를 구성하였고, 확률 형태로 변형하였다. 확률에 대한 랜덤변수를 도입하고, 물리적 위치 변수와 랜덤변수를 연결하여 물리학적 기호를 도입하였다. 기호변화의 패턴을 유도하고 물리적 기호의 변화모델을 구성하였다. 모델은 점프형, 표류형과 확산형 변화 패턴을 예측하고, 주가흐름의 패턴에서 약 2분, 약 3.5분과 약 6분 정도에 나타나는 것을 보였다. 또한 인문학적인 도상기호, 상징기호와 지표기호가 모델에서 예측되는 것을 보였다.

• 한국자기학회지
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• 제21권5호
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• pp.185-192
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• 2011

박막제조 기술은 과학 기술의 기초가 되는 분야로 양질의 박막을 제조하기 위한 다양한 노력이 경주되고 있다. 박막제조는 표면개질과 함께 표면처리 기술의 한 분야이며 이중 진공증착으로 알려진 물리증착법과 화학증착법은 현대의 과학기술 연구는 물론 산업적으로 폭넓게 이용되는 박막제조 기술 중의 하나이다. 진공증착을 이용한 박막제조 기술은 나노 기술의 등장과 함께 비약적인 발전을 이루었으며 자연모사와 완전화 박막의 제조, 융복합 공정을 이용한 기능성 코팅과 Engineered Structure 구현 그리고 초고속 증착과 원가 저감 기술의 실현이 주요 이슈로 등장하고 있다. 본 논문에서는 물리증착법과 화학증착법을 중심으로 박막제조 기술의 종류와 원리를 설명하고 박막제조 기술의 최신 동향과 기술적 이슈 및 향후 전망에 대해 기술한다.

• Advances in nano research
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• 제10권5호
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• pp.449-460
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• 2021

Flexoelectricity is an interesting materials' property that is more touchable in small scales. This property beside the sandwich structures placed in the center of scientists' attention due to their extraordinary effects on the mechanical properties. Furthermore, in the passage of decades, more elaborated sandwich structures took into consideration results from using honeycomb core. This kind of structure, inspiring from honeycomb core, provides more stiffness to weight ratio, which plays a crucial role in different industries. In this paper, based on the Love-Kirchhoff's hypothesis, Hamilton's principle, modified couple stress theory and Fourier series analytical method, equations of motion for a sandwich plate containing a honeycomb core integrated by two face-sheets have derived and solved analytically. The equations of both face sheets have derived by flexoelectricity consideration. Moreover, it should be noticed that the whole structure rests on the visco-Pasternak foundation. Conducting current research provided an acceptable and throughout study based on flexoelectricity to address the effect of materials' characteristics, length-scale parameter, aspect, and thickness ratios and boundary conditions on the natural frequency of honeycomb sandwich plates. Also, based on the presented figures and tables, there is a close agreement between previous studies and recent work. Due to the high ratio of strength to weight, current model analyzing is capable of taking into account for different vehicles' manufacturing in a high range of industries.

• Advances in nano research
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• 제10권5호
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• pp.415-422
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• 2021

Silicene, a 2D allotrope of silicon, is predicted to be a potential material for future transistor that might be compatible with present silicon fabrication technology. Similar to graphene, silicene exhibits the honeycomb lattice structure. Consequently, silicene is a semimetallic material, preventing its application as a field-effect transistor. Therefore, this work proposes the uniform doping bandgap engineering technique to obtain the n-type silicene nanosheet. By applying nearest neighbour tight-binding approach and parabolic band assumption, the analytical modelling equations for band structure, density of states, electrons and holes concentrations, intrinsic electrons velocity, and ideal ballistic current transport characteristics are computed. All simulations are done by using MATLAB. The results show that a bandgap of 0.66 eV has been induced in uniformly doped silicene with phosphorus (PSi₃NW) in the zigzag direction. Moreover, the relationships between intrinsic velocity to different temperatures and carrier concentration are further studied in this paper. The results show that the ballistic carrier velocity of PSi₃NW is independent on temperature within the degenerate regime. In addition, an ideal room temperature subthreshold swing of 60 mV/dec is extracted from ballistic current-voltage transfer characteristics. In conclusion, the PSi₃NW is a potential nanomaterial for future electronics applications, particularly in the digital switching applications.

• 공업화학
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• 제22권2호
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• pp.185-189
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• 2011

본 연구에서는 화학적 공침법을 적용하여 가스상 이산화탄소 분해를 위한 나노크기의 M-페라이트(M=Co, Ni, Cu, Zn)를 제조하였다. 열중량 분석 결과, 시험제조한 모든 시료의 최고 무게 감소율은 $350^{\circ}C$ 미만에서 발생하였다. 소성온도가 증가할수록 결정형은 우수하여 표면촉매활성화를 기대할 수 있지만, 입자결정의 크기가 크고, 비표면적이 낮은 페라이트가 합성됨을 알 수 있었다. FT-IR 분석으로부터 $375{\sim}406cm^{-1}$의 범위에서 octahedral site에 착화물이 존재함을 확인 할 수 있었으며, 이는 페라이트 내 스피넬 구조가 형성되어 있음을 보여주는 것이라고 믿는다. 본 연구로부터 얻은 이산화탄소 분해반응을 위한 금속페라이트의 최적 열처리 온도는 $500^{\circ}C$인 것으로 나타났다.

• Advances in nano research
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• 제13권3호
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• pp.259-267
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• 2022

Two-dimensional (2D) transition metal carbides/nitrides or "MXenes" belong to a diverse-class of layered compounds, which offer composition- and electric-field-tunable electrical and physical properties. Although the majority of the MXenes, including Ti₃C₂T_x, are metallic, they typically show semiconductor-like behaviour in their percolated thin-film structure; this is also the most common structure used for fundamental studies and prototype device development of MXene. Magnetoconductance studies of thin-film MXenes are central to understanding their electronic transport properties and charge carrier dynamics, and also to evaluate their potential for spin-tronics and magnetoelectronics. Since MXenes are produced through solution processing, it is desirable to develop deposition strategies such as inkjet-printing to enable scale-up production with intricate structures/networks. Here, we systematically investigate the extrinsic negative magnetoconductance of inkjetprinted Ti₃C₂T_x MXene thin-films and report a crossover from weak anti-localization (WAL) to weak localization (WL) near 2.5K. The crossover from WAL to WL is consistent with strong, extrinsic, spin-orbit coupling, a key property for active control of spin currents in spin-orbitronic devices. From WAL/WL magnetoconductance analysis, we estimate that the printed MXene thin-film has a spin orbit coupling field of up to 0.84 T at 1.9 K. Our results and analyses offer a deeper understanding into microscopic charge carrier transport in Ti₃C₂T_x, revealing promising properties for printed, flexible, electronic and spinorbitronic device applications.

• Advances in nano research
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• 제13권2호
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• pp.187-197
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• 2022

The synthesis of organic and hybrid organic-inorganic perovskites directly from solution improves the cost- and energy-efficiency of processing. To date, numerous research efforts have been devoted to investigating the influence of the various solvent parameters for the synthesis of lead halide perovskites, focused on the effects of different single solvents on the efficiency of the resulting perovskites. In this work, we investigated the effect of solvent blends for the first time on the structure and phase of perovskites produced via the Lewis base vapor diffusion method to develop a new synthetic approach for water-stable CsPbBr₃ particles with nanometer-sized dimensions. Solvent blends prepared with DMF and water-miscible solvents with different Gutmann's donor numbers (D_N) affect the Pb ions differently, resulting in a variety of lead bromide species with various colors. The use of a DMF/isopropanol solvent mixture was found to induce the formation of the Ruddlesden-Popper perovskite based on lead bromide. This perovskite undergoes a blue color shift in the solvated state owing to the separation of nanoplatelets. In contrast, the replacement of isopropanol with DMSO, which has a high DN, induces the formation of spherical CsPbBr₃ perovskite nanoparticles that exhibit green emission. Finally, the integration of acetone in the solvent system leads to the formation of lead bromide complexes with a yellow-orange color and the perovskite CsPbBr₃.

• 한국압력기기공학회 논문집
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• 제17권2호
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• pp.145-156
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• 2021

Ultrasonic Nanocrystal Surface Modification (UNSM) is a peening technology that generates elastic-plastic deformation on the material surface to which a static load of a air compressor and a dynamic load of ultrasonic vibration energy are applied by striking the material surface with a strike pin. In the UNSM-treated material, the structure of the surface layer is modified into a nano-crystal structure and compressive residual stress occurs. When UNSM is applied to welds in a reactor coolant system where PWSCC can occur, it has the effect of relieving tensile residual stress in the weld and thus suppressing crack initiation and propagation. In order to quantitatively evaluate the compressive residual stress generated by UNSM, many finite element studies have been conducted. In existing studies, single-path UNSM or UNSM in a limited area has been simulated due to excessive computing time and analysis convergence problems. However, it is difficult to accurately calculate the compressive residual stress generated by the actual UNSM under these limited conditions. Therefore, in this study, a minimum finite element peening analysis area that can reliably calculate the compressive residual stress is proposed. To confirm the validity of the proposed analysis area, the compressive residual stress obtained from the experiment are compared with finite element analysis results.

• 예술인문사회 융합 멀티미디어 논문지
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• 제7권3호
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• pp.291-300
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• 2017

양자점 셀룰라 오토마타(QCA: quantum-dot cellular automata)는 셀룰라 오토마타와 유사하게 고안된 컴퓨팅 모델이며, 빠른 연산속도와 적은 전력손실로 차세대의 각광받는 기술도 떠오르고 있다. QCA는 최근 실험 결과와 함께 다양한 연구가 진행되고 있으며 나노 단위 소재로서 디바이스 밀도 및 상호 연결 문제를 해결할 수 있는 트랜지스터의 패러다임 중 하나이다. XOR(exclusive or) 게이트는 논리의 둘 중 하나가 참일 때 결과가 참이 되도록 작동하는 게이트이다. 제안하는 XOR 게이트는 5개의 층으로 구성되어 있다. 첫 번째 층은 OR 게이트, 세 번째 층과 다섯 번째 층은 AND 게이트로 구성되어 있고 중간에 두 번째 층과 네 번째 층은 통로로 구성하여 설계한다. 반가산기는 XOR 게이트와 AND 게이트로 이루어져 있다. 제안한 반가산기는 제안하는 XOR 게이트에서 셀 두 개를 추가하여 설계한다. 제안한 반가산기는 기존의 반가산기에 비해 보다 적은 수의 셀, 전체 면적, 그리고 클럭으로 구성한다.

• Advances in nano research
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• 제14권5호
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• pp.435-442
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• 2023

Sports activities, including playing tennis, are popular with many people. As this industry has become more professionalized, investors and those involved in sports are sure to pay attention to any tool that improves athletes' performance Tennis requires perfect coordination between hands, eyes, and the whole body. Consequently, to perform long-term sports, athletes must have enough muscle strength, flexibility, and endurance. Tennis rackets with new frames were manufactured because tennis players' performance depends on their rackets. These rackets are distinguished by their lighter weight. Composite rackets are available in many types, most of which are made from the latest composite materials. During physical exercise with a tennis racket, nanocomposite materials have a significant effect on reducing injuries. Materials as strong as graphite and thermoplastic can be used to produce these composites that include both fiber and filament. Polyamide is a thermoplastic typically used in composites as a matrix. In today's manufacturing process, materials are made more flexible, structurally more vital, and lighter. This paper discusses the production, testing, and structural analysis of a new polyamide/Multi-walled carbon nanotube nanocomposite. This polyamide can be a suitable substitute for other composite materials in the tennis racket frame. By compression polymerization, polyamide was synthesized. The functionalization of Multi-walled carbon nanotube (MWCNT) was achieved using sulfuric acid and nitric acid, followed by ultrasonic preparation of nanocomposite materials with weight percentages of 5, 10, and 15. Fourier transform infrared (FTIR) and Nuclear magnetic resonance (NMR) confirmed a synthesized nanocomposite structure. Nanocomposites were tested for thermal resistance using the simultaneous thermal analysis (DTA-TG) method. scanning electron microscopy (SEM) analysis was used to determine pores' size, structure, and surface area. An X-ray diffraction analysis (XRD) analysis was used to determine their amorphous nature.