• Steel and Composite Structures
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• v.27 no.2
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• pp.201-216
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• 2018

In this paper, three-dimensional (3D) elasticity theory in conjunction with nonlocal strain gradient theory (NSGT) is developed for mechanical analysis of anisotropic nanoparticles. The present model incorporates two scale coefficients to examine the mechanical characteristics much accurately. All the elastic constants are considered and assumed to be the functions of (r, ${\theta}$, ${\varphi}$), so all kind of anisotropic structures can be modeled. Moreover, all types of functionally graded spherical structures can be investigated. To justify our model, our results for the radial vibration of spherical nanoparticles are compared with experimental results available in the literature and great agreement is achieved. Next, several examples of the radial vibration and wave propagation in spherical nanoparticles including nonlocal strain gradient parameters are presented for more than 10 different anisotropic nanoparticles. From the best knowledge of authors, it is the first time that 3D elasticity theory and NSGT are used together with no approximation to derive the governing equations in the spherical coordinate. Moreover, up to now, the NSGT has not been used for spherical anisotropic nanoparticles. It is also the first time that all the 36 elastic constants as functions of (r, ${\theta}$, ${\varphi}$) are considered for anisotropic and functionally graded nanostructures including size effects. According to the lack of any common approximations in the displacement field or in elastic constant, present theory can be assumed as a benchmark for future works.

• Journal of the Korean Chemical Society
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• v.21 no.2
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• pp.75-82
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• 1977

The isotope effect of pure liquid on vapor pressure is examined, and the vapor pressure ratios of two different isotopes are calculated. Based on the Significant Structure Theory of Liquids, the effect of molecular weight and the effect of moments of inertia are dominant in ordinary/trans-$d_2$ ethylene isotopes; the effect of hindered rotational zero-point energy is dominant in trans-$d_2$/cis-$d_2$ ethylene isotopes; and the effect of intermolecular potential difference is found in $CH_3OH/CH_3OD$ isotopes. In the isotopes of $CH_4/CD_4,\;SiH_4/SiD_4\;and\;GeH_4/GeD_4$, the weight effect decrease in the order of $CH_4/CD_4 >SiH_4/SiD_4 >GeH_4/GeD_4$.

• Bulletin of the Korean Chemical Society
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• v.24 no.6
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• pp.728-730
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• 2003

Bond lengths, harmonic vibrational frequencies and dissociation energies of TlAt are calculated at ab initio molecular orbital and density functional theory using effective spin-orbit operator and relativistic effective core potentials. Spin-orbit effects estimated from density functional theory are in good agreement with those from ab initio calculations, implying that density functional theory with effective core potentials can be an efficient and reliable methods for spin-orbit interactions. The estimated $R_e$, $ω_e$ and $D_e$ values are 2.937 ${\AA}$, 120 $cm^{-1}$, 1.96 eV for TlAt. Spin-orbit effects generally cause the bond contraction in Group 13 elements and the bond elongation in the Group 17 elements, and spin-orbit effects on Re of TlAt are almost cancelled out. The spinorbit effects on $D_e$ of TlAt are roughly the sum of spin-orbit effects on $D_e$ of the corresponding element hydrides. Electron correlations and spin-orbit effects are almost additive in the TlAt molecule.

• Journal of Korea Technology Innovation Society
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• v.2 no.2
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• pp.201-218
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• 1999

The article contains an introduction of possibility of applying Multi-Attribute Utility Theory(MAUT) for priority setting of R&D projects. MAUT is compared with AHP, which is widely used recently. These two techuiques are applied to set priorities of R&D projects In a Government-funded Research Institute. Six criteria are chosen from consultation with decision makers. They are composed of 1) validity as representative projects, 2) possibility of resource mobilization, 3) spillover effect of developed technologies, 4) possibility of success, 5) scope of participation and 6) clarity of research goal. To set priorities of R&D projects, SMART(Simple MultiAttribute Rating Technique) and DVM(Difference Value Measurement) out of many MAUT methods are used to design the utility function and to determine the weights among criteria. The aggregation model is additive on the assumption the criteria are independent. AHP executes pairwise comparisons for criteria and alternatives. From the results of the case study, the results and theoretical characteristics are compared.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1669-1680
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• 2010

The phase-shifted version of the multichannel quantum-defect theory (MQDT) was reformulated by disentangling the interloper spectrum from the perturbed dense Rydberg series for a systems involving 2 closed and more than 1 open channel. The theory was applied successfully to Martins and Zimmermann's photoionization spectra of the Rydberg series Cu I $3d^9\;4s(^1D_2)\;nd^2G_{9/2}$ perturbed by the interloper, $3d^9\;4p^2\;^4F_{9/2}$, for which Cohen's 4 channel QDT had failed. The zero surface graphic of the perturbed Fano's asymmetry parameter q of the autoionization spectrum of dense Rydberg series by the interloper was determined by only two parameters for this system. It was used as a map to trace the transformation route of the 3 channel autoionization spectra to the 4 channel spectra when the channel coupling of the closed channels with a newly added open channel was turned on progressively.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.12
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• pp.1013-1020
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• 2017

In this study, the failure prediction of composite laminates under flexural loading is investigated. A FEA(finite element analysis) using 2D strain-based interactive failure theory. A pregressive failure analysis was applied to FEA for stiffness degradation with failure mode each layer. A three-point bending test based on the ASTM D790 are performed for cross-ply $[0/90]_8$ and quasi-isotropic $[0/{\pm}45/90]_{2s}$ laminated composites. The accuracy of the applied failure theory is verified with the experimental results and other failure criteria such as maximum strain, maximum stress and Tsai-Wu theories.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.11
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• pp.4372-4394
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• 2020

The distribution of popular videos incurs a large amount of traffic at the base stations (BS) of networks. Device-to-multi-device (D2MD) communication has emerged an efficient radio access technology for offloading BS traffic in recent years. However, traditional studies have focused on synchronous user requests whereas asynchronous user requests are more common. Hence, offloading BS traffic in case of asynchronous user requests while considering their time-varying characteristics and the quality of experience (QoE) of video request users (VRUs) is a pressing problem. This paper uses social stability (SS) and video loading duration (VLD)-tolerant property to group VRUs and seed users (SUs) to offload BS traffic. We define the average amount of data transmission (AADT) to measure the network's capacity for offloading BS traffic. Based on this, we formulate a time-varying bipartite graph matching optimization problem. We decouple the problem into two subproblems which can be solved separately in terms of time and space. Then, we propose the socially aware D2MD user selection (SA-D2MD-S) algorithm based on finite horizon optimal stopping theory, and propose the SA-D2MD user matching (SA-D2MD-M) algorithm to solve the two subproblems. The results of simulations show that our algorithms outperform prevalent algorithms.

• Journal of the Korean Mathematical Society
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• v.54 no.4
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• pp.1301-1316
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• 2017

It is well known that every $x{\in}(0,1]$ can be expanded to an infinite $L{\ddot{u}}roth$ series with the form of $$x={\frac{1}{d_1(x)}}+{\cdots}+{\frac{1}{d_1(x)(d_1(x)-1){\cdots}d_{n-1}(x)(d_{n-1}(x)-1)d_n(x)}}+{{\cdots}}$$, where $d_n(x){\geq}2$ for all $n{\geq}1$. In this paper, the set of points with some restrictions on the digits in $L{\ddot{u}}roth$ series expansions are considered. Namely, the Hausdorff dimension of following the set $$F_{\phi}=\{x{\in}(0,1]\;:\;d_n(x){\geq}{\phi}(n),\;i.o.n}$$ is determined, where ${\phi}$ is an integer-valued function defined on ${\mathbb{N}}$, and ${\phi}(n){\rightarrow}{\infty}$ as $n{\rightarrow}{\infty}$.

• Korea Trade Review
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• v.47 no.2
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• pp.47-67
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• 2022

This study is to investigate the relationships between R&D collaboration and competitive advantage in Korean international venture firms from the perspective of resource-based theory, organizational learning and network theory. The R&D collaboration is divided into vertical cooperation within the value chain and horizontal cooperation beyond value chain. The first key finding from empirical analysis is that both vertical and horizontal R&D collaborations have significantly positive impacts on technology based competitive advantages. The vertical R&D collaboration has more impacts on competitive advantages than horizontal R&D collaboration. This suggests that R&D collaboration with purchasers and suppliers plays a greater role for venture organizations' competitiveness. Second, the potential knowledge based absorption capacity and mutual goodwill trust also work significantly to reinforce the positive influences of R&D collaboration to the competitive advantage. This implies that mutual trust between partners participating in collaboration and absorption capacity within venture organizations would strengthen the effectiveness of R&D cooperation. This study provides the practical implications that the performance and effectiveness of R&D collaboration may rely on the nature of cooperation partners and internal organization capability.

• Journal of Information Technology Services
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• v.17 no.3
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• pp.77-100
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• 2018

As the importance of R&D has recently become more important, the budget for national R&D projects has continued to grow. Along with, there is a growing awareness to use and manage R&D funds transparently. This study examines the relationship among attitude toward the behavior (ATT), subjective norm (SN), perceived behavioral control (PBC) and behavioral Intention (BI) deriving from TPB (Theory of planned Behavior). To empirically prove the hypothesis, the statistical analysis were conducted based on the response from the 2,021 RCMS users, using SPSS 21.0 and AMOS 21.0. The research model variable consists of ATT, SN, PBC, BI, person type, RCMS characteristics. The results of study can be summarized as follows. First, ATT, SN, PBC have the positive effect on BI. Second, According to the type of person (Director, R&D supporter), there is no difference in ATT on BI but there is a difference in SN (or PBC) on BI. Third, The type of person have moderating effects in the relationship between ATT and BI. Finally, All RCMS characteristics have moderating effects in the relationship between ATT and BI. Some RCMS characteristics have moderating effects in the relationship between PBC and BI.