• Journal of the Optical Society of Korea
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• v.19 no.6
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• pp.560-565
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• 2015

We report efficient direct coupling of THz dipole antenna pulses onto air spaced two-wire transmission lines and Teflon covered two-wire lines. The air spaced two-wire lines show TEM mode propagation with very small group velocity dispersion (GVD) and relatively low attenuation. The Teflon covered two-wire lines showed comparatively much higher attenuation and GVD. However, the Teflon covered two-wire lines show a very good guiding property when the lines are curved. Although the lines are circled only 5.0 cm in diameter, there is no additional attenuation compared to straight the lines.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.4 s.346
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• pp.31-37
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• 2006

Strongly motivated by the need for significant reduction in the optics-to-antenna interface circuitry used in a Photonically controlled array, it has proposed the design development of a novel 'true photonic antenna' consisted of optical fiber and micro-strip antenna. To clarify the design capability of the geometry, modal transmission-line theory including the discontinuity property between circular i,nd planar guiding structures is defined, md the optical power coupling of a slot-coupled microstrip antenna directly fed from an optical fiber using photoconductive effect is evaluated numerically. The numerical results reveal that the maximum power transfer between the two different guiding structures occurs at a new point in which the guiding powers of two rigorous modes are equally partitioned.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.5
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• pp.516-521
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• 2015

This study is about a hydrogen mitigation system in a containment building like an offshore or a nuclear plant. A hydrogen explosion is possibly happened after condensation of steam if hydrogen releases with steam in a containment buildings. Passive autocatalytic recombiner is the one of the measures, but the performance of this equipment is not sure because the distribution of hydrogen is very irregular and is not predicted correctly. This study proposes a new approach for improving the hydrogen removing performance with hydrogen-guiding property. The steam is simulated and analysed. The results show that the shallow air containment reduced over 55% of the released hydrogen and the deep air containment type reduces over 80% of released hydrogen.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.4
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• pp.27-33
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• 2003

Circular Distributed-feedback (DFB) guiding structures can be incorporated in most of the semiconductor laser devices because of the frequency-selective property applicable as an optical filter in optical communications. In this paper, we present a novel and simple modal transmission-line theory (MTLT) using Floquet-Babinet's principle to analyze the optical filtering characteristics of Bragg gratings with cylindrical profile. The numerical results reveal that this method offers a simple and convenient algorithm to analyze the filtering characteristics of circular DFB configurations as well as is extended conveniently to evaluate the guiding problems of circular multi-layered periodic structures.

• Informatization Policy
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• v.24 no.4
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• pp.44-67
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• 2017

Commercial properties are gaining importance in the national economy, drawing more and more interests from agencies and individuals. Therefore, objective and accurate investment information needs to be supplied in order to support rational decision making and market transparency. To contribute to guiding the Korean commercial property market to become as transparent and competitive as the markets of developed countries, this study aims to seek for ways to establish a Korean commercial property information framework. As part of the activities to achieve the goal, the Korean commercial property market information was first evaluated in terms of data collection, production and operation. Then, US NCREIF, which is operated by the private sector, and Singapore's URA, managed by the public sector, were considered as the examples of well-managed foreign commercial property market information frameworks. Efficient management of the system requires establishing a monitoring scheme, and users' accessibility and information availability will be enhanced through phased expansion of the information.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.5
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• pp.537-543
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• 2010

This paper presents a slot-shaped defected ground structure(DGS) which has multi-band rejection property. The proposed structure, in which the spiral slot-shaped defects with different size are aligned in the transverse direction to the guiding direction of the coplanar waveguide(CPW), provides multiple resonance frequencies. Compared with the simulated results, the band rejection characteristic is in good agreement with the measurement. Also, an equivalent circuit model of the proposed structure is presented, where the DGS on the ground plane is modeled as LC-resonators. This resonators are inductively coupled to the signal line through mutual inductance. From the equivalent circuit model, multi-band rejection property was derived.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.12
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• pp.3277-3285
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• 1996

In this paper, w designed an opical power distribution device for application to an optical switching and an optical subscriber loop. We fabricated PSG thin film by LPCVD. Based on the measured index of fabricted thin film, rib-type waveguide was transformed to two-dimension by the effective index method and we simulated dispersion property to find asingle-mode condition. We found that the optimum design parameters of rib-type waveguide are:cladding layer of 3.mu.m, core layer of 3.mu.m, buffer layer of 10.mu.m, and core width of 4.mu.m. Each side of the guiding region was etched down to 4.mu.m to shape the core. We used these optimum parameters of the rib-type waveguide with branching angle of 0.5.deg. and simulted the Y-branch waveguide by the BPM simulation. Numerical loss in branching area was claculated to be 0.1581dB and equal to the total loss of the Y-branch. The loss of the fabricated Y-branch waveguide on PSG film ws 1.6dB at .lambda.=1.3.mu.m before annealing but was 1.2dB after annealing at 1000.deg. C for 10 minutes. Consequently, the loss of branching area from 3000.mu.m to 6000.mu.m in the z-direction was 0.8dB, and single-mode propagation was confirmed by measuring the near field pattern. For coupling the fabricated Y-branch waveguide with an optical fiber, we fabricated V-groove which was used as the upholder of optical fiber. An etching angle was 54.deg. and the width and depth of guiding groove was 150.mu.m, 70.mu.m, respectively. The optical fiber is inserted onto V-groove. Both the Y-branch and V-groove were connected through the index matching oil. Coupling loss after connecting Y-branch and the optical fiber on V-groove was 0.34dB and that after injecting index mateching oil was 0.14dB.

• Korean journal of communication and information
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• v.50
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• pp.143-163
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• 2010

This study explores the headlines of the metro sections posted in the major domestic news media during 1998 and 2009 and examines if the media contribute to construction of the reality. The data were systematical sampled from three main evening news programs representing each broadcasting company and the seven major nationwide newspapers (n=53,765). Results suggest the selection of news items should be influenced by the property of the regime and the trend for the time. This influence led to similarity among the news media to some extent, which are partially explained by the objectivity principle guiding the whole process of news making. Meanwhile, there was clear difference among the news media in general, and between the medium (broadcasting vs. newspaper) and within a medium, more specifically. The difference can be explained by the interaction of the property of the regime and the trend for the time and other factors including journalistic paradigm and ownership of each company.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.7
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• pp.42-49
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• 1999

In this paper, we proposed a simple measurement method to find the behaviors of the fiber-to-waveguide coupler. The polished fiber blocks and planar waveguides on silicon dioxide were fabricated independently and then optically coupled by physical pressure. Several kinds of polymer with different refractive indices were used for waveguide films. The proposed method makes it possible to measure the center wavelength, bandwidth, extinction ratio, and polarization dependence of the coupler during fabrication procedure. The wavelength sensitivity increased with refractive index of polymer. The symmetric planar waveguide structure and isotropic property of guiding materials reduced polarization dependent property. Insertion loss of the coupler was less than 0.5dB. It is expected that our measurement method is useful for developing various optical devices using evanescent coupling between polished fiber and planar waveguide such as optical modulators and filters etc.

• Journal of Sensor Science and Technology
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• v.27 no.4
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• pp.209-215
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• 2018

Recent research in animal behavior has shown that gradient information plays an important role in finding food and home. It is also important in optimization of performance because it indicates how the inputs should be adjusted for maximization/minimization of a performance index. We introduce perturbation as an additional input to obtain gradient information. Unlike the typical approach of calculating the gradient from the derivative, the proposed processing is very robust to noise since it is performed as a summation. Experimental results prove the validity of the process of spatial gradient acquisition. Quantitative indices for measuring the effect of the amplitude and the frequency are developed based on linear regression analysis. Drones are very useful for environmental monitoring and an autonomous path planning is required for unstructured environment. Guiding the drone for finding the origin of the interested physical property is done by estimating the gradient of the sensed value and generating the drone trajectories in the direction which maximizes the sensed value. Simulation results show that the proposed method can be successfully applied to identify the source of the physical quantity of interest by utilizing it for path planning of an autonomous drone in 3D environment.