• Advances in nano research
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• v.15 no.4
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• pp.339-353
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• 2023

This work aims to present a solution for the buckling behavior of perforated nano/microbeams with deformable boundary conditions using nonlocal strain gradient theory (NLSGT). For the first time, a solution that can provide buckling loads based on the non-local and strain gradient effects of perforated nanostructures on an elastic foundation, while taking into account both deformable and rigid boundary conditions. Stokes' transformation and Fourier series are used to realize this aim and determine the buckling loads under various boundary conditions. We employ the NLSGT to account for size-dependent effects and utilize the Winkler model to formulate the elastic foundation. The buckling behavior of the perforated nano/microbeams restrained with lateral springs at both ends is studied for various parameters such as the number of holes, the length and filling ratio of the perforated beam, the internal length, the nonlocal parameter and the dimensionless foundation parameter. Our results indicate that the number of holes and filling ratio significantly affect the buckling response of perforated nano/microbeams. Increasing the filling ratio increases buckling loads, while increasing the number of holes decreases buckling loads. The effects of the non-local and internal length parameters on the buckling behavior of the perforated nano/microbeams are also discussed. These material length parameters have opposite effects on the variation of buckling loads. This study presents an effective eigenvalue solution based on Stokes' transformation and Fourier series of the restrained nano/microbeams under the effects of elastic medium, perforation parameters, deformable boundaries and nonlocal strain gradient elasticity for the first time.

• Journal of ILASS-Korea
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• v.19 no.4
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• pp.174-181
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• 2014

This study investigates the effects of nanoparticle size and temperature on the thermal conductivity enhancement of water-based alumina ($Al_2O_3$) nanofluids, using the centrifuging method and relative centrifugal forces of differing magnitude to produce nanofluids of three different particles without involving any dispersants or surfactants. We determined the coupling dependency in thermal conductivity enhancement relative to nanoparticle size and temperature of the alumina nanofluids and also experimentally showed that the effect of temperature on thermal conductivity is strongly dependent on nanoparticle size. Also, our experimental data presented that the effective medium theory models such as the Maxwell model and Hasselman and Johnson model are not sufficient to explain the thermal conductivity of nanofluids since they cannot account for the temperature- and size-dependent nature of water-based alumina nanofluids.

• Computers and Concrete
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• v.21 no.4
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• pp.431-440
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• 2018

Fluid velocity analysis on the instability of pipes reinforced by silica nanoparticles ($SiO_2$) is presented in this paper. Mori-Tanaka model is used for obtaining the effective materials properties of the nanocomposite structure considering agglomeration effects. The well known Navier-Stokes equation is used for obtaining the applied force of fluid to pipe. Based on the Reddy higher-order shear deformation theory, the motion equations are derived based on energy method and Hamilton's principal. The frequency and critical fluid velocity of structure are calculated using differential quadrature method (DQM) so that the effects of different parameters such as volume fractions of SiO2 nanoparticles, SiO2 nanoparticles agglomeration, boundary conditions and geometrical parameters of pipes are considered on the nonlinear vibration and instability of the pipe. Results indicate that increasing the volume fractions of SiO2 nanoparticles, the frequency and critical fluid velocity of the structure are increased. Furthermore, considering SiO2 nanoparticles agglomeration, decreases the frequency and critical fluid velocity of the pipe.

• Journal of Information Science Theory and Practice
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• v.1 no.2
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• pp.69-83
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• 2013

This paper aims to determine the preference and use of electronic information and resources by blind/visually impaired users in the leading National Capital Region (NCR) libraries of India. Survey methodology has been used as the basic research tool for data collection with the help of questionnaires. The 125 in total users surveyed in all the five libraries were selected randomly on the basis of willingness of the users with experience of working in digital environments to participate in the survey. The survey results were tabulated and analyzed with descriptive statistics methods using Excel software and 'Stata version 11'. The findings reveal that ICT have a positive impact in the lives of people with disabilities as it helps them to work independently and increases the level of confidence among them. The Internet is the most preferred medium of access to information among the majority of blind/visually impaired users. The 'Complexity of content available on the net' is found as the major challenge faced during Internet use by blind users of NCR libraries. 'Audio books on CDs/DVDs and DAISY books' are the most preferred electronic resources among the majority of blind/visually impaired users. This study will help the library professionals and organizations/institutions serving people with disabilities to develop effective library services for blind/visually impaired users in the digital environment on the basis of findings on information usage behavior in the study.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.3
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• pp.449-459
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• 1999

The scattering problems from electromagnetic absorbers can be greatly simplified using the transmission line approximations (TLA) and effective medium theory. This method has been widely used for the absorber design because of its very simple calculation and intuitional approach, while numerical analysis needs the tremendous computation requirements, This paper examined the accuracy and limitations originated by the intrinsic approximation limits of TLA by comparison with FEM results for various absorber design examples. It was found that the TLA result is valid when λ $\geq$ 2p, where λ is the wavelength of the interested upper frequency and p is the distance between two periodic cone arrays. Therefore, the electromagnetic absorbers having high material properties and big base-area commonly do not meet this condition, and the electromagnetic scattering from those absorbers must be evaluated by the numerical analysis in those cases.

• Korean Journal of Optics and Photonics
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• v.1 no.1
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• pp.73-86
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• 1990

The technique of Spectroscopic Ellipsometry (SE) has been examined with emphasis on its inherent sensitivity to the existence of thin films or surface equivalents. A brief review of related theories like the Fresnel reflection coefficients, the effect of a multilayer upon reflectivities, together with the validity of the effective medium theory and the modelling procedure, is followed by a short description of the experimental setup of a rotating polarizer type SE as well as the necessful expressions which lead to tan and cos. Out of its numerous, successful applications, a few are exampled to convince a reader that SE can be applied to a variety of research fields related to surface, interface and thin films. Specifically, those are adsorption and/or desorption on metals or semiconductors, oxidation process, formation of passivation layers on an electrode, thickness determination, interface between semiconductor and its oxide, semiconductor heterojunctions, surface microroughness, void distribution of dielectric, optical thin films, depth profile of multilayered samples, in-situ or in-vitro characterization of a solid surface immersed in electrolyte during electrochemical, chemical, or biological treatments, and so on. It is expected that the potential capability of SE will be widely utilized in a very near future, taking advantage of its sensitivity to thin films or surface equivalents, and its nondestructive, nonperturbing characteristics.

• Journal of Distribution Science
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• v.13 no.3
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• pp.61-67
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• 2015

Purpose - Exports have long been regarded as significant drivers of sustainable competitive advantage and growth among small and medium enterprises (SMEs). The export activities of SMEs are particularly important in the context of export-oriented economies such as Korea. Although many studies have examined the determinants of exports, it is difficult to find empirical studies about the determinants of the export performance of regional SMEs. This study investigates the determinants of export performance in the regional SME context based on an integrated approach that combines the environment factor of industrial organization theory, competitive strategy theory, and the competences of the resource-based view. Research design, data, and methodology - To empirically analyze the determinants of export performance in the regional SMEs, data were collected from firms in the Daegu metropolitan area. Data were collected directly through questionnaire surveys; in addition, secondary financial data were also taken from the KIS-VALUE database. Out of the 175 responses that were received, 143 were considered to be worth examining. After testing the reliability and validity of the variables through multiple items such as environmental turbulence and competitive strategy, hypotheses were verified by using five multi-regression models. These models were: a control model with organizational size and age, an environmental model with technology and market turbulence, a competency model with R&D and foreign distribution channels, a strategy model with product and market differentiation, and an integrated model including all of these variables. Results - First, as a control variable, the organization size has significant positive effects on export performance. Second, technology turbulence based on industrial organization theory has significant positive effects on export performance, but market turbulence does not affect export performance. Third, the foreign market distribution competency of the resource-based view has strong positive effects on export performance, but the R&D competency does not affect export performance. Fourth, the product differentiation strategy from competitive strategy theory positively impacts export performance, but market differentiation does not affect export performance. Finally, in the integrated model, only the foreign distribution competency of the resource-based view has a significant effect on export performance. Conclusions - The empirical results of this study verified the usefulness of the rationales behind the three theories to explain the export performance of the regional SMEs, especially the importance of the foreign market distribution competency from the resource-based view. With regard to practical considerations, this study's implications suggest that the use of technological environmental changes by industries is better than the use of market changes. Further, the use of the product differentiation strategy is more effective than the use of the market-driving strategy, and the distribution channel competency plays a stronger role than the technology-oriented competency with regard to the export performance position of regional SMEs. Future studies should examine relational perspectives, such as trust among channel partners. Therefore, the configuration approach is more useful in enhancing pragmatism by comparing high- and low-export companies.

• Asia pacific journal of information systems
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• v.23 no.2
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• pp.41-66
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• 2013

IS outsourcing has an important meaning to the Korean SME's (Small and Medium Enterprises) which want to use the IS Services. The objective of this research is to manage IT risks occurred during IS outsourcing project process. This study tries to identify these risks using real option methodology. In order to perform this objective, this study set up the research model which is composed of two main concepts. The first one is the risk factors occurred during IS outsourcing project process: User's Risks, Supplier's Risks and Transaction's Risks. All of these risks are based on Transaction Cost Theory. The second one is the intention to get (or buy) Real Options to manage the risks. In the research model, two types of real option are included: option to abandon (put option) and option to defer (call option). This study uses questionnaires and statistics methodology (PLS) to analyze the hypotheses proposed in the research model. Compared with prior studies, this study is different in two ways. First, this study restricts the range of IT risks. Prior researches of IT Risk management in MIS area cover various range of IT risks, but this study focuses on the Korean SME's IT outsourcing risks on the basis of Transaction Cost Theory. This study tests the relationship between the risks and real option types. Second, this study tries to test the moderating effect of user's risks and supplier's risks on the relationship between transaction's risks and real option types. In IT outsourcing research area, almost studies focus on the direct relationships between IT risks and outsourcing success. But in reality, the co-relationship among IT risks may occur. There are some findings according to the research analysis. First, risks related with user's risks have strong causal relationships with the intention to get option to abandon (put) and option to defer. But risks related with supplier's risks have causal relationships only with option to abandon (put). Second, user's risks and supplier's risks have no moderating effect on the relationship between transaction's risks and real option types. According to the research results, this research have some important and interesting implications on the IS outsourcing business area. First, this study identifies the effective types of real option to minimize the risks occurred during the IT outsourcing projects. So IS outsourcing service users can manage (or minimize) effectively the risks, which occurred during outsourcing projects, using real options. Second, real option gives benefits to suppliers and users at the same time (i.e., win-win strategies between IS outsourcing service providers and users). Vendors (:IS outsourcing service providers) can offer users the real options which can minimize the occurrence of risks in time. "IN TIME" means that before the IS outsourcing project starts, vendors can offer users the opportunity to buy real options in appropriate prices to manage the possibility of the risks of IS outsourcing project. And users also have chance to minimize the IT outsourcing risks occurred during the project process using real options.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.3
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• pp.277-286
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• 2000

Switch-based network is suitable for the environment of demanding high performance network. Traditional shared-medium Local Area Networks(LANs) do not provide sufficient throughput and latency. Specially, communication performance is more important with multimedia application. In these environments, switch-based network results in high performance. A kind of switch-based network provides higher bandwidth and low latency. Thus high-speed switch is essential to build switch-based LANs. An effective switch design is the most important factor of the switch-based network performance, and is required for the multicast message processing. In the previous cut-through switching technique, switch element reconfiguration has the capability of multicasting and deadlock-free. However, it has problems of low throughput as well as large scale of switch. Therfore, effective multicating can be implemented by using divided hardware unicast and multicast. The objective of this thesis is to suggest switch configuration with these features.

• The Research Journal of the Costume Culture
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• v.19 no.4
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• pp.751-765
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• 2011

The purpose of this study is to apply the Trencadis images in Antony Gaudi's work to a design motive and thus provide a new concept for a knitwear design by combining double-knitted fabrics with patchwork applique, taping, stitching and quilting. This study examines the bibliographic text and precedent research related to Antony Gaudi and his works, and analyzes the historical background and formative and stylistic characteristics of Trencadis as it appeared in Gaudi's architectural works. Also this study also examines the characteristics of knitwear and knitting theory while exploring the formative elements and the combined techniques used in modern knitwear design through fashion magazines, medium images, and online sources. The results are as follows: First, Gaudi's work that applies a Trencadis technique has the characteristic of being creative, organic, and environmentally friendly. And in addition, its colorfulness inspires modern fashion design. Second, computerized knitting has been practiced in various ways and the fabrics knitted by both double-knitting jacquard and computerized knitting machines provide a new direction the creation of knitwear. A computerized knitting machine is especially effective for pictorial expression, and is suitable for showing the natural curve of the human body due to its sophistication. Third, as a result of applying a combined technique to the knitting of various fabrics, a combined or fusion design, which is a recent megatrend, is very effective for the design of knitwear while increasing its aesthetic value. Moreover, utilizing techniques that combine patchwork applique, taping, stitching and quilting will create higher value in knitwear. Lastly, with a project of applying combined techniques in the creation of knitwear, designers can become much more creative while taking their imagination much further.