• Journal of the Korea Institute of Military Science and Technology
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• v.3 no.1
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• pp.155-163
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• 2000

A general characterization procedure based on the extraction of a 2n-port admittance matrix corresponding to n uniform coupled lines on the multi-layered substrate using the Finite-Difference Time-Domain (FDTD) technique is presented. The frequency-dependent normal mode parameters are obtained from the 2n-port admittance matrix, which in turn provides the frequency-dependent distributed inductance and capacitance matrices. To illustrate the technique, several practical coupled line structures on multi-layered substrate, including a three-line structure, have been simulated. It is shown that the FDTD based time domain characterization procedure is an excellent broadband simulation tool for the design of multiconductor coupled lines on multilayered PCBs as well as thick or thin hybrid structures.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.117-120
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• 2000

When analyzing the scatting problem of multi-layered structures using closed-form Green's function, one of the main difficulties is that the numerical integrations for the evaluation of diagonal matrix elements converge slowly and are not so stable. Accordingly, even when the integration for the singularity of type e$\^$-jkr//${\gamma}$/, corresponding to the source dipole itself, is performed using such a mathod, this difficulty persists in the integration corresponding to the finite number of complex images. In order to resolve this difficulty, a new technique based upon the Gaussian quadrature in polar coordinates for the evaluation of the two-dimensional generalized exponential integral is presented. Stability of the algorithm and convergence is discussed. Performance is demonstrated for the example of a microstrip patch antenna.

• Journal of the Korean Geophysical Society
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• v.9 no.1
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• pp.63-71
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• 2006

When surveying the cultural heritages especially in the case of stone structures, preserving their originalstate is of primary importance. For the effective assessment of survey results of stone structure, thedynamic characteristics of that system should be considered. Dynamic characteristics of stone masonry structures depend on several factors such as coefficients of friction, contact conditions, and number of layers of bonding stones. These factors can be estimated by using the dynamic analysis results. This paper describes a method for natural frequency determination of traditional stone arch bridge subjected to compressive force. For this purpose, multi-layered granite brick models of for arch bridge were made and fundamental frequencies corresponding increasing axial forces were measured.

• Journal of the Korean Society for Advanced Composite Structures
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• v.3 no.4
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• pp.17-26
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• 2012

This study presents a governing equations of bending behavior of anisotropic sandwich plates with multi-layered laminated composite faces. Based on zig-zag models for through thickness deformations, the shear deformation of composite faces is included. All edges of plate are assumed to be simply supported. Results of the bending analysis under lateral loads are presented for the influence of various lay up sequences of antisymmetric angle-ply laminated faces. The accuracy of the approach is ascertained by comparing solutions from the sandwich plates theory with composite faces to the laminated plates theory. Since the present analysis considers the bending stiffness of the core and also the transverse shear deformations of the laminated faces, the proposed method showed higher than that calculated according to the general laminated plates theory. The information presented might be useful to design sandwich plates structure with polymer matrix composite faces.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.189.1-189.1
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• 2013

Titanium dioxide (TiO2) is a wide bandgap semiconductor possessing photochemical stability and thus widely used for photocatalysis. However, enhancing photocatalytic efficiency is still a challenging issue. In general, the efficiency is affected by physio-chemical properties such as crystalline phase, crystallinity, exposed crystal facets, crystallite size, porosity, and surface/bulk defects. Here we propose an alternative approach to enhance the efficiency by studying interfaces between thin TiO2 layers to be stacked; that is, the interfacial phenomena influencing on the formation of porous structures, controlling crystallite sizes and crystallinity. To do so, multi-layered TiO2 thin films were fabricated by using a sol-gel method. Specifically, a single TiO2 thin layer with a thickness range of 20~40 nm was deposited on a silicon wafer and annealed at $600^{\circ}C$. The processing step was repeated up to 6 times. The resulting structures were characterized by conventional electron microscopes, and followed by carrying out photocatalytic performances. The multi-layered TiO2 thin films with enhancing photocatalytic efficiency can be readily applied for bio- and gas sensing devices.

• Archives of Craniofacial Surgery
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• v.21 no.3
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• pp.143-155
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• 2020

Surgical anatomy for Asian rhinoplasty Part I reviewed layered anatomy with neurovascular system of the nose. Part II discusses upper two-thirds of nose which consists of nasal bony and cartilaginous structures. Nasal physiology is mentioned briefly since there are several key structures that are important in nasal function. Following Part III will cover lower one-third of nose including in-depth anatomic structures which are important for advanced Asian rhinoplasty.

• 한국초전도학회:학술대회논문집
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• v.15
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• pp.31-31
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• 2005

• Journal of the Ergonomics Society of Korea
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• v.36 no.5
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• pp.437-446
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• 2017

Objective: This study aims to draw an efficient UI design by comparing the usability of App drawer and single-layered home screens, which are smartphone home screens. Background: Because smartphone home screen is frequently used including the installation, deletion, and editing of APPs, it should be designed with easily controllable information structure. There is a need to seek a user-friendly UI by comparing the usability of App drawer and single-layered home screens, of which methods to search Apps are different. There is also a need to examine an efficient UI and the factors to improve from the user perspective. Method: This study targeted 30 Android OS and iOS users to evaluate the App drawer and single-layered home screens, of which UI structures are different. Each participant was instructed to carry out an App searching task and App deleting task, and the execution time and the number of errors were measured. After the tasks were completed, they evaluated satisfaction through a questionnaire survey. Results: In the App searching task with low task level, there was no difference in execution level between the App drawer and single-layered home screens. However, the single-layered home screen showed higher efficiency and accuracy in the App deleting task with high task level. As for the group difference according to use experience, there was no difference in satisfaction among Android OS users, but iOS user satisfaction with single-layered home screen with which they were familiar was higher. Conclusion: As for home screen usability, the single-layered home screen UI structure can be advantageous, as task level is higher. Repulsion was higher, when users, who had used easier UI, used complex UI in comparison with user satisfaction, when users familiar with complex UI used easier UI. A UI indicating the current status with clear label marking through a task flow chart-based analysis, and a UI in which a user can immediately recognize by exposing hidden functions to the first depth were revealed as things to improve. Application: The results of this study are expected to be used as reference data in designing smartphone home screens. Especially, when iOS users use Android OS, the results are presumed to contribute to the reduction of predicted barriers.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.3
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• pp.16-22
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• 2013

A general characterization procedure based on the extraction of a 2n-port admittance matrix corresponding to n uniform coupled lines on the multi-layered substrate using the Finite-Difference Time-Domain (FDTD) technique is presented. In this paper, the frequency-dependent normal mode parameters are obtained from the 2n-port admittance matrix to analyze multi-layered asymmetric coupled line structure, which in turn provides the frequency-dependent propagation constant, effective dielectric constant, and line-mode characteristic impedances. To illustrate the technique, several practical coupled line structures on multi-layered substrate have been simulated. Especially, embedded conductor structures have been simulated. Comparisons with Spectral Domain Method are given, and their results agree well. It is shown that the FDTD based time domain characterization procedure is an excellent broadband simulation tool for the design of multiconductor coupled lines on multilayered PCBs as well as thick or thin hybrid structures.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2256-2262
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• 2011

In this study, sound transmission loss (STL) is investigated on the multi-layered windows used in the KTX-sancheon and next generation HEMU-400x high speed train. Using TLOSS, which is developed as a special purpose STL analysis program, STLs of the multi-layered glass windows are analytically investigated and compared with the mass law result. Window specimens for the two train models are manufactured and intensity transmission losses are measured based on ASTM E2249-02. The problems in aspect of sound insulation are diagnosed on the two window models. The aim of this study is to provide useful data for the improvement of the interior noise in the high speed train.