• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1533-1538
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• 2008

The development of new material systems like Carbon Fiber Reinforced Polymer (CFRP) places ever higher demands on the techniques for non-destructive material characterisation. Image-producing eddy current methods also need to satisfy these demands. Eddy-current imaging of FRP is based on the anisotropic electrical properties of the material investigated. Significant differences in conductivity between carbon fibres, polymer matrix and integrated functional components can be found. The availability of high-resolution sensors enables access to the local distribution of the electromagnetic properties. The static and dynamic procedures for isolating influential characteristics, already in use in eddy-current technology, can now be supplemented by topographical images. The precondition for a successful implementation of the eddy-current procedure is a deeper understanding of the image-generating process which allows correct interpretation of the images obtained.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.9
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• pp.2854-2865
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• 1996

The concept of variable-geometry truss structure(VGTS) is introduced as a class of actively controlled adaptive structure. VGTS can purposefully vary its geometric configurations by changing the lengths of some members of the structure. General kinematics and inverse kinematics of a statically determinate VGTS(variable geometry truss structure) are studied. The solution technique is based on the Jacobian matrix obtained via joint equilibrium equations. Pseudoinverse control method is applied to resolve the redundancy of a large VGTS. two types of actuator layout of octahedral type VGTS, VG truss and Stewart platform, are compared. Introducing the concept of performance index, Stewart platform based layout was found to has less consumption energy and manipulation time. A functional VGTS model with 3 octahedral modules is designed and manufactured for the labaratory demonstration. Six vertically located length-variable members are used to create general 6 d.o.f. motions.

• 전기의세계
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• v.29 no.4
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• pp.247-255
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• 1980

In this study, an application of Finite Element Method which, in principle, based on variational calculus has been presented for the two-dimensional analysis of magnetic flux distribution in the shell type core of single phase transformer. The necessary stationarity condition of energy functional and boundary conditions were determined under the assumptions that the electromagnetic field considered is stationary and that the effect of eddy current is negligible. In the process of application the domain of magnetic field was divided into triangle subsectional elements and then the matrix equations were constructed for the respective triangular element and for those of all after the manipulation of minimization process to the vector potential of magnetic field at the each vertex of the element. Furthermore the numerical computation for the equations was guided by the Gaussian Elimination Methods. As the results obtained, it is found that the aspect of magnetic flux distribution inside the core as well as the leakage flux profile at the vicinity of the inner leg of the core is not much different from the well-known distribution profile of magnetic flux, however, the procedure shows to possess the merit of the uniquely deterministic nature for the flux distribution at the desired points.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.304-307
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• 2015

Carbon nanotubes (CNTs) have been widely accepted and used as the enhancer for polymer nano-composites due to their remarkable mechanical properties. Understandably, the CNT fiber-polymer matrix interface plays a major role in determining the properties of the CNT-polymer nano-composites. Here, using the LCAODFT Lab tool available on the EDISON Nano-Physics site, we performed first-principles density-functional theory calculations to determine the atomic configurations and binding energies of the CNTs in contact with polymers. For the polymer matrixes, we chose poly(acrylonitrile) (PAN), which is one of the most well-known polymer matrixes for the carbon nanofiber nanocomposites. Different chiralities and diameters of pristine CNTs were considered, and several PAN-CNT configurations were prepared based on the atomistic positions and directions of cyano group in PAN. The most favorable configuration of PAN was obtained when the PAN bound parallel to the surface of CNT. Our finding indicates the binding configurations are determined by the direction of the cyano group dominantly rather than the atomistic position of PAN, or the symmetry of CNTs. The result of increasing the length of CNT diameter suggests that PAN is inclinable to align evenly on the surface of relatively large size of CNT with the configuration parallel to the surface. These results obtained in this study will provide the starting point for the design of improved PAN-CNT composites for the next-generation ultra-strong and ultra-light carbon nanofibers.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.3-10
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• 2001

The box system that is composed only of reinforced concrete walls and slabs are adopted on many high-rise apartment buildings recently constructed in Korea. And the framed structure with shear wall core that can effectively resist horizontal forces is frequently adopted for the structural system for high-rise building structures. In these structures, a shear wall may have one or more openings for functional reasons. It is necessary to use subdivided finite elements for accurate analysis of the shear wall with openings. But it would take tremendous amount of computational time and memory if the entire building structure is subdivided into a finer mesh . An efficient analysis method that can be used regardless of the number, size and location of openings is proposed in this study, The analysis method uses super element, substructure, matrix condensation technique and fictitious beam technique. Three-dimensional analyses of the box system and the framed structure with shear wall core having various types of openings were performed to verify the efficiency of the proposed method. It was confirmed that the proposed method have outstanding accuracy with drastically reduced time and computer memory from the analyses of example structures.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.264-270
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• 1998

This research broadens the prime concern of nuclear power plant operations from safe performance to both economic and safe performance. First emergency diesel generator is identified as one of main contributors for the lost plant availability through the review of plants forced outage records. The framework of an integrated architecture for performing modern on-line condition for operational availability improvement is configured in this work. For the development of the comprehensive sensor networks for complex target systems, an integrated methodology incorporating a structural hierarchy, a functional hierarchy, and a fault-system matrix is formulated. The second part of our research is development of intelligent diagnosis and maintenance advisory system, which employs Bayesian Belief networks (BBNs) as a high level reasoning tool incorporating inherent uncertainty use in probabilistic inference. Our prototype diagnosis algorithms are represented explicitly through topological symbols and links between them in a causal direction. As new evidence from sensor network development is entered into the model especially, our advisory of system provides operational advice concerning both availability and safety, so that the operator is able to determine the likely modes, diagnose the system state, locate root causes, and take the most advantageous action. Thereby, this advice improves operational availability

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.654-654
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• 2013

One of the most important yet unresolved problems in molecular electronics is the controversy over the number and nature of multiple conductance peaks in single-molecule junctions. Currently, there are three competing explanations of this observation: (1) manifestation of different molecule-electrode contact geometries, (2) formation of gauche defects within the molecular core, (3) involvement of different electrode surface orientations [1]. However, the exact origin of multiple conductance peaks is not yet fully understood, which indicates our incomplete understanding of the scientifically as well as techno-logically important organic-metal contacts. To theoretically resolve this problem, we previously applied a multiscale computational approach that combines force fields molecular dynamics (FF MD), density functional theory (DFT), and matrix Green's function (MGF) calculations [2] to a thermally fluctuating haxanedithiol (C6DT) molecule stretched between flat Au(111) electrodes, but could observe only a single conductance peak [3]. In this presentation, using DFT geometry optimizations and MGF calculations, we consider molecular junctions with more realistic molecule-metal contact conformations and Au(111) electrode surface directions. We also conduct DFT-based molecular dynamics for the highly stretched junction models to confirm our conclusion. We conclude that the S-Au coordination number should be the more dominant factor than the electrode surface orientation.

• The Journal of Korean Society for Radiation Therapy
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• v.7 no.1
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• pp.92-96
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• 1995

All patients who will Undergo irraidiation of the oral cavity cancer will need dental before and during Radiotherapy. The extent of the region and the presence of numerous critical normal tissues(mucosa, gingiva, teeth and the alveolar ridge, alveolar bony structure, etc) in the oral cavity area, injury to which could result in serious functional impairment. Therefore I evaluate the Usefulness of custom-made intraoral shielding device before and during Radiotherapy in oral cavity cancer. Materials and Methods(1) : Manufacture process of Custom-made intraoral shielding device Containing Cerroband. A. Acquisition of impression B. Matrix Constitution C. Separation by Separator D. Sprincle on method E. Trimming F. Spacing G. Fill with Cerroband Materials and Methods (2) A. Preannealing B. TLD Set up C. Annealing D. TLD Reading = Results = Therefore dosimetric characteristics in oral cavity by TLD Compared to isodose curve dose distribution Ipsilateral oral mucosa, Contralateral oral mucosa, alveolar ridge, tongue, dose was reduced by intraoral shielding device containning Cerroband technique Compard to isodose plan = Conclusions = The custom-made intra-oral shielding device containing Cerroband was useful in reducing the Contralateral oral mucosa dose and Volume irradiated.

• International Journal of Oral Biology
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• v.42 no.4
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• pp.191-196
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• 2017

Transglutaminase2 (TGM2) is a multi-functional calcium dependent enzyme that affects angiogenesis, apoptosis, differentiation, attachment, and changes in the extracellular matrix. However, its function in periodontal tissue has not yet been studied. The aim of this study was to investigate the association of the TGM2 expression and the modulation of inflammatory mediators in inflamed periodontal ligament (PDL) cells induced by pro-inflammatory cytokines such as Interleukin-$1{\beta}$ and the Tumor necrosis $factor-{\alpha}$. The expression of TGM2 was increased in the inflamed periodontal tissue and PDL cells. Over-expressed TGM2 in the PDL cells increased expression of MMP1, MMP3, IL-6, CXCL8, and PTGS2. Conversely, inhibition of TGM2 activity using LDN27219, a TGM2 inhibitor, resulted in decreased expression of MMP1, MMP3, IL-6, and CXCL8. The mRNA expression was confirmed by RT-PCR and quantified by qRT-PCR. Protein levels were also confirmed by immunofluoroscence staining. These results suggest that TGM2 plays an important role in the regulation of inflammatory mediators which exacerbate tissue damage in inflamed periodontal tissue.

• Child Health Nursing Research
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• v.13 no.4
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• pp.444-453
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• 2007

Purpose: The purpose of this study was to develope a tool to assess mothers' behavior related to healt promotion if their preschool children had disabillties. Method: The research design was a methodological study. This tool was developed in 4 stages: first, a content matrix as a conceptual framework was developed using Gordon's 11 functional health promotion patterns and 5 categories (Lee, Jung & An, 1996); second,40 preliminary items were selected through references and interviews with 9 mothers of children with disabilities; third, 2 items were discarded after content validity was done by 3 experts; fourth, reliability and validity were tested with a sample of 243 mothers of children with disabilities who were of preschool age. Results: The final tool consisted of 19 items and Cronbach's alpha coefficient for internal consistency was .82. Five factors were extracted by factor analysis and they explained 55.58% of the total variance. Conclusions: This tool was identified to have a high degree of reliability and validity. So it can be utilized to assess mothers' behavior in providing health promotion for their children who have disabilities.