• Bulletin of the Korean Chemical Society
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• v.24 no.6
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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.

• Composites Research
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• v.37 no.3
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• pp.170-178
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• 2024

This study proposes a hybrid composite where a thin copper film (Cu film) is embedded in carbon fiber reinforced plastic (CFRP), and quantum annealing is applied to derive the combination of Cu film placement that maximizes the through-thickness thermal conductivity. The correlation between each ply of CFRP and the Cu film is analyzed through finite element analysis, and based on the results, a combination optimization problem is formulated. A formalization process is conducted to embed the defined problem into quantum annealing, resulting in the formulation of objective functions and constraints regarding the quantity of Cu films that can be inserted into each ply of CFRP. The formulated equations are programmed using Ocean SDK (Software Development Kit) and Leap to be embedded into D-Wave quantum annealer. Through the quantum annealing process, the optimal arrangement of Cu films that satisfies the maximum through-thickness thermal conductivity is determined. The resulting arrangements exhibit simpler patterns as the quantity of insertable Cu films decreases, while more intricate arrangements are observed as the quantity increases. The optimal combinations generated according to the quantity of Cu film placement illustrate the inherent thermal conductivity pathways in the thickness direction, indicating that the transverse placement freedom of the Cu film can significantly affect the results of through-thickness thermal conductivity.

• 한국초전도학회:학술대회논문집
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• 2007.07a
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• pp.12-12
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• 2007

• Bulletin of the Korean Chemical Society
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• v.16 no.9
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• pp.801-803
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• 1995

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.8
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• pp.17-24
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• 2004

Quantum effects in the poly-gate are analyzed in two dimensions using the density-gradient method, and their impact on the short-channel effect of double-gate MOSFETs is investigated. The 2-D effects of quantum mechanical depletion at the gate to sidewall oxide is identified as the cause of large charge-dipole formation at the corner of the gate. The bias dependence of the charge dipole shows that the magnitude of the dipole peak-value increases in the subthreshold region and there is a large difference in carrier and potential distribution compared to the classical solution. Using evanescent-nude analysis, it is found that the quantum effect in the poly-gate substantially increases the short-channel effect and it is more significant than the quantum effect in the Si film. The penetration of potential contours into the poly-gate due to the dipole formation at the drain side of the gate corner is identified as the reason for the substantial increase in short-channel effects.

• Journal of the Korean Ceramic Society
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• v.53 no.3
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• pp.317-324
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• 2016

Continued miniaturization and increasingly exact requirements for thin film deposition in the semiconductor industry is driving the search for new effective, efficient, selective precursors and processes. The requirements of defect-free, conformal films, and precise thickness control have focused attention on atomic layer deposition (ALD). ALD precursors so far have been developed through a trial-and-error experimental approach, leveraging the expertise and tribal knowledge of individual research groups. Precursors can show significant variation in performance, depending on specific choice of co-reactant, deposition stage, and processing conditions. The chemical design space for reactive thin film precursors is enormous and there is urgent need for the development of computational approaches to help identify new ligand-metal architectures and functional co-reactants that deliver the required surface activity for next-generation thin-film deposition processes. In this paper we discuss quantum mechanical simulation (e.g. density functional theory, DFT) applied to ALD precursor reactivity and state-of-the-art automated screening approaches to assist experimental efforts leading toward optimized precursors for next-generation ALD processes.

• Korean Journal of Materials Research
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• v.12 no.4
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• pp.296-303
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• 2002

For potential application to quantum mechanical devices, nano-composite thin films, consisting of GaAs quantum dots dispersed in SiO$_2$ glass matrix, were fabricated and studied in terms of structural, chemical, and optical properties. In order to form crystalline GaAs quantum dots at room temperature, uniformly dispersed in $SiO_2$matrix, the composite films were made to consist of alternating layers of GaAs and $SiO_2$in the manner of a superlattice using RF magnetron sputter deposition. Among different film samples, nominal thickness of an individual GaAs layer was varied with a total GaAs volume fraction fixed. From images of High Resolution Transmission Electron Microscopy (HRTEM), the formation of GaAs quantum dots on SiO$_2$was shown to depend on GaAs nominal thickness. GaAs deposits were crystalline and GaAs compound-like chemically according to HRTEM and XPS analysis, respectively. From measurement of optical absorbance using a spectrophotometer, absorption edges were determined and compared among composite films of varying GaAs nominal thicknesses. A progressively larger shift of absorption edge was noticed toward a blue wavelength with decreasing GaAs nominal thickness, i.e. quantum dots size. Band gaps of the composite films were also determined from Tauc plots as well as from PL measurements, displaying a linear decrease with increasing GaAs nominal thickness.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1796-1801
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• 2001

For micro-machines, very few design methodologies based on optimization hale been developed so far. To overcome the difficulties of design optimization of micro-machines, the search method for multi-dimensional design window (DW)s is proposed. The proposed method is defined as areas of satisfactory design solutions in a design parameter space, using both continuous evolutionary algorithms (CEA) and the modified K-means clustering algorithm . To demonstrate practical performance of the proposed method, it was applied to an optimal shape design of micro electrostatic actuator of optical memory. The shape design problem has 5 design parameters and 5 objective functions, and finally shows 4 specific design shapes and design characters based on the proposed DWs.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.343-356
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• 2022

As a part of round robin analysis to develop a finite element elastic-plastic seismic analysis procedure for nuclear safety class 1 components, a series of parametric analyses was carried out on the simulated pressurizer surge line system model to investigate sensitivity of the analysis results to finite element analysis variables. The analysis on the surge line system model considered dynamic effect due to the seismic load corresponding to PGA 0.6 g and elastic-plastic material behavior based on the Chaboche combined hardening model. From the parametric analysis results, it was found that strains such as accumulated equivalent plastic strain and equivalent plastic strain are more sensitive to the analysis variables than von Mises effect stress. The parametric analysis results also identified that finite element density and ovalization option in the elbow elements have more significant effect on the analysis results than the other variables.

• Progress in Medical Physics
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• v.21 no.3
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• pp.261-273
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• 2010

For the use of Indirect-conversion CMOS (complementary metal-oxide-semiconductor) detectors for digital x-ray radiography and their better designs, we have theoretically evaluated the spatial-frequency-dependent detective quantum efficiency (DQE) using the cascaded linear-systems transfer theory. In order to validate the developed model, the DQE was experimentally determined by the measured modulation-transfer function (MTF) and noise-power spectrum, and the estimated incident x-ray fluence under the mammography beam quality of W/Al. From the comparison between the theoretical and experimental DQEs, the overall tendencies were well agreed. Based on the developed model, we have investigated the DQEs values with respect to various design parameters of the CMOS x-ray detector such as phosphor quantum efficiency, Swank noise, photodiode quantum efficiency and the MTF of various scintillator screens. This theoretical approach is very useful tool for the understanding of the developed imaging systems as well as helpful for the better design or optimization for new development.