• EDISON SW 활용 경진대회 논문집
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• 제4회(2015년)
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• pp.151-155
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• 2015

The molecular interactions between the nucleic acid bases and water molecules are important in organism. Despite Adenine-Thymine Hoogsteen base pair and Guanine-Cytosine Watson-Crick base pair have been demonstrated to be most stable in a gas phase, the effect of water on the stability of these base pairs remains elusive. Here we report the structural and thermodynamic characteristics on possible Adenine-Thymine and Guanine-Cytosine base pairs in a gas phase as well as in an aqueous phase by using quantum mechanical method and statistical mechanical calculations. First, we optimized the direct base-pair interaction energies of four Adenine-Thymine base pairs (Hoogsteen base pair, reverse Hoogsteen base pair, Watson-Crick base pair, and reverse Watson-Crick base pair) and three Guanine-Cytosine base pairs (GC1 base pair, GC2 base pair, and Watson Crick base pair) in a gas phase at the $B3LYP/6-31+G^{**}$ level. Then, the effect of solvent was quantified by the electronic reorganization energy and the solvation free energy by statistical mechanical calculations. Thereby, we discuss the effect of water on the stability of Adenine-Thymine and Guanine-Cytosine base pairs, and argue why Adenine-Thymine Watson-Crick base pair and Guanine-Cytosine Watson-Crick base pair are most stable in an aqueous environment.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 춘계학술대회
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• pp.611-613
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• 2021

최근, 고전컴퓨터(Classic Computer)의 한계를 뛰어넘는 양자컴퓨터(Quantum Computer)에 대한 연구개발이 다양한 분야에서 활발하게 이루어지고 있다. 고전컴퓨터의 전기적인 신호처리와는 다르게 양자역학적인 원리를 사용한 양자컴퓨터는 양자 중첩(Quantum Superposition), 양자 얽힘(Quantum Entanglement)과 같은 다양한 양자역학의 현상/특성을 활용하여 연산을 수행하기 때문에 고전컴퓨터의 연산에 비해 아주 복잡한 연산과정을 거치게 된다. 또한, 큐비트의 종류, 배치, 연결성 등 실제 양자컴퓨터를 구동시키기 위해 구성되는 많은 요소들에 의한 각각의 영향이 양자컴퓨터의 연산 결과와 연산 과정에서 많은 영향을 끼치기 때문에 각각의 요소를 효율적이고 정확하게 활용하기 위해 실제 양자컴퓨터의 구동 이전에 데이터를 시각화하여 오류검증/최적화/신뢰성검증을 할 필요가 있다. 하지만 양자컴퓨터 내부에 구성된 다양한 요소들의 데이터를 전부 시각화 할 경우 직관적으로 원하는 데이터를 파악하는 것이 어렵기 때문에 선별적으로 데이터를 시각화 할 필요가 있다. 본 논문에서는 양자컴퓨터를 구성하는 다양한 요소들의 데이터를 시각화 하여 직관적으로 데이터를 관측하고 활용할 수 있도록 복잡하게 구성되는 양자컴퓨터 내부 회로 구성요소들을 계층적으로 시각화 하는 방법을 제안한다.

• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
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• pp.122-123
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• 2000

Fock-state is a highly non-classical radiation-field state. So if one can generate a Fock-state it is possible to study many interesting quantum-mechanical aspects. But in spite of its attraction, it is very difficult to generate a Fock-state experimentally although there have been many theoretical and experimental efforts to do it. Recently Chough et. al.$^{(1)}$ proposed a feasible scheme to achieve quasi number states. The key is to exploit the multi-photon resonances occurring in a driven Jaynes-Cummings system, so it is important to understand the processes at multi-photon resonances. In the present work we study the dynamics of multi-photon resonances in the driven Jaynes-Cummings system. (omitted)

• JSTS:Journal of Semiconductor Technology and Science
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• 제6권1호
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• pp.1-9
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• 2006

We introduce our in-house program, NANOCAD, for the modeling and simulation of carrier transport in nanoscale MOSFET devices including quantum-mechanical effects, which implements two kinds of modeling approaches: the top-down approach based on the macroscopic quantum correction model and the bottom-up approach based on the microscopic non-equilibrium Green’s function formalism. We briefly review these two approaches and show their applications to the nanoscale bulk MOSFET device and silicon nanowire transistor, respectively.

• Transactions on Electrical and Electronic Materials
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• 제5권5호
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• pp.173-179
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• 2004

The influence of heavily Si impurity doping in the GaN barrier of InGaN/GaN multi-quantum well structures of blue light emitting diodes were investigated by growing samples in metal-organic chemical vapor deposition. The delta-doped sample was compared to the sample with the undoped barrier. The delta-doped sample shows the tunneling behavior and forms the energy level of 0.32 eV for tunneling and the photoemission of the 450-nm band. The photo-luminescence shows the blue-shifted broad band of the radiative transition due to the inclusion of Si delta-doped layer indicating that the delta doping effect acts to form the higher energy level than that of quantum well. The dislocation may provide the carrier tunneling channel and plays as a source of acceptor. During the tunneling of hot carrier, there was no light emission.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 제5회 영호남 학술대회 논문집
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• pp.121-125
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• 2003

Time-resolved photoluminescence from InGaN/GaN multi-quantum well structures was investigated for two different shapes of square- and trapezoidal wells grown by metal-organic chemical vapor deposition. To compare to the conventional square well structure with a radiative recombination lifetime of 0.170 nsec, the large value of lifetime of 0.540 nsec from trapezoidal well were found at room temperature. This value is similar to the value for GaN host material indicating no confinement effect of quantum well. Furthermore, the high resolution transmission electron microscopy image provides the In clustering effect in the trapezoidal well structure.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1376-1381
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• 2004

Understanding the thermal conductivity and heat transfer processes in superlattice structures is critical for the development of thermoelectric materials and optoelectronic devices based on quantum structures. $Chen^{(1)}$ developed ballistic diffusive equation(BDE) for alternatives of the Boltzmann equation that can be applied to the complex geometrical situation. In this study, a simulation code based on BDE is developed and applied to the 1-dimensional transient heat conduction across a thin film and transient 2-dimensional heat conduction across the film with heater. The obtained results are compared to the results of the $Chen^{(1)}$ and Yang and $Chen^{(1)}$. Finally, steady 2-dimensional heat conduction in the quantum dot superlattice are solved to obtain the equivalent thermal conductivity of the lattice and also compared with the experimental data from $Borca-Tasciuc^{(2)}$.

• 한국초전도ㆍ저온공학회논문지
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• 제25권1호
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• pp.1-5
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• 2023

The study of two-dimensional electron systems with extraordinarily low levels of disorder was, for a long time, the exclusive privilege of the epitaxial thin film research community. However, the successful isolation of graphene by mechanical exfoliation has truly disrupted this field. Furthermore, the assembly of heterostructures consisting of several layers of different 2D materials in arbitrary order by exploiting van der Waals forces has been a game-changer in the field of low-dimensional physics. This technique can be generalized to the large class of strictly 2D materials and offers unprecedented parameters to play with in order to tune electronic and other properties. It has led to a paradigm shift in the field of 2D condensed matter physics with bright prospects. In this review article, we discuss three device fabrication techniques towards high mobility devices: suspended structures, dry transfer, and pick-up transfer methods. We also address state-of-the-art device structures, which are fabricated by the van der Waals pick-up transfer method. Finally, we briefly introduce correlated ground states in the fractional quantum Hall regime.

• 대한전자공학회논문지SD
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• 제41권6호
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• pp.1-7
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• 2004

본 논문에서는 2차원 양자 역학적 모델링 및 시뮬레이션(quantum mechanical modeling and simulation)으로써, 자기정렬 이중게이츠 구조(self-aligned double-gate structure)인 FinFET에 관하여 결합된 푸아송-슈뢰딩거 방정식(coupled Poisson and Schrodinger equations)를 셀프-컨시스턴트(self-consistent)한 방법으로 해석하는 수치적 모델을 제안한다. 시뮬레이션은 게이트 길이(Lg)를 10에서 80nm까지, 실리콘 핀 두께($T_{fin}$)를 10에서 40nm까지 변화시켜가며 시행되었다. 시뮬레이션의 검증을 위한 전류-전압 특성을 실험 결과값과 비교하였으며, 문턱 전압 이하 기울기(subthreshold swing), 문턱 전압 롤-오프(thresholdvoltage roll-off), 그리고 드레인 유기 장벽 감소(drain induced barrier lowering, DIBL)과 같은 파라미터를 추출함으로써 단채널 효과를 줄이기 위한 소자 최적화를 시행하였다. 또한, 고전적 방법과 양자 역학적 방법의 시뮬레이션 결과를 비교함으로써,양자 역학적 해석의 필요성을 확인하였다. 본 연구를 통해서, FinFET과 같은 구조가 단채널 효과를 줄이는데 이상적이며, 나노-스케일 소자 구조를 해석함에 있어 양자 역학적 시뮬레이션이 필수적임을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제24권6호
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• pp.824-828
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• 2003

Our previous quantum mechanical calculations using polyalanine model systems showed that the monodipolemacrodipoleinteractions selectively stabilize α-helices and make it possible for α-helices to be formed inhydrophobic environment where the solvent effect is not available. The monodipole-macrodipole interactionsin α-helices were studied molecular mechanically using various point-charge systems available. The resultsshow that all the point-charge systems used in the calculations produce the monodipole-macrodipoleinteractions up to about 60% compared to the results of the quantum mechanical calculations. The results ofmolecular mechanical calculations are explained and discussed compared to the results of the quantummechanical calculations.