• Journal of Korean Society of Transportation
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• v.24 no.6 s.92
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• pp.75-85
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• 2006

Recently. large number of countires have been focused on the construction of container seaport and hub airport to enrole as the center of logistics. In particular, the East Asian nations have been enhanced their airports' facilities in order to accommodate for demand of global market environment. In Korea, Incheon International Airport (ICN) was opened in 2001 to take leading role as the Northeast Asian main hub airport. The purpose of this research is to analyze the transferring connectivity at ICN. To analyze its connectivity, this research has been applies two methodologies ; wane structure and minimum or maximun connection time analysis It has analyzed the temporal configuration as the frequency and quality of indirect connections offered by an airline by adopting a wave-system structure in the airline flight schedule. As an empirical analysis, it also calculated the minimum and maximum connection time adopting Korean Air's flight information.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.4
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• pp.313-320
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• 2001

In the presence of incident waves with different frequencies, there are second order sum and difference frequency wane exciting forces due to the nonlinearty of the incident waves. Although the magnitudes of these nonlinear forces are small, they act at sum and difference frequencies away from those of the incident waves. So, the second order sum and difference frequency wane loads occurring close to the natural frequencies of TLPs often give greater contributions to high and low frequency resonant responses. The components of the second order forces which depend on first order quantities have been evaluated using the three dimensional source distribution method. The numerical results of time domain motion analysis for the nonlinear wave exciting forces in regular waves are compared with the numerical ones of frequency domain analysis. The results of comparison confirmed the validity of the proposed approach.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.2
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• pp.341-349
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• 2002

The radar method is becoming one of the major nondestructive testing(NDT) techniques lot concrete structures. Numerical modeling of electromagnetic wane is needed to analyze radar measurement results. Finite difference-time domain(FD-TD) method can be used to simulate electromagnetic wave propagation through concrete specimens. Five concrete specimens with different thickness are modeled in 3-dimension. Radar modeling results compare measurement results to find backface of the concrete specimens and measure thickness of the concrete specimens.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.1
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• pp.39-50
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• 2007

This paper presents 3D infinite elements for the elastodynamic problem with multi-layered half-space. Five different types of infinite elements are formulated by using approximate expressions of multiple wave components for the wave function in multi-layered soil media. They are horizontal, horizontal-corner, vortical, vertical-corner and vertical-horizontal-comer infinite elements. The elements can effectively be used for simulating wane radiation problems with multiple wave components. Numerical example analyses are presented for rigid disk, square footings and embedded footing on homogeneous and layered half-space. The numerical results show the effectiveness of the proposed infinite elements.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.7 s.361
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• pp.105-111
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• 2007

In this paper, we designed and fabricated a 3-dB tandem coupler using air-bridge technology for millimeter-wane monolithic integrated circuits, operating at W-band($75{\sim}110\;GHz$) frequency. Tightly edge-coupled CPW line has low directivity due to different even-mode and odd-mode phase velocity. To overcome this disadvantage, a 3-dB tandem coupler which comprises the two-sectional weakly parallel-coupled lines with equal phase velocity was designed at W-band. The proposed coupler was fabricated using air-bridge technology to monolithically materialize the uniplanar coupler structure instead of conventional multilayer or wire bonded structure. From the measurements, the coupling coefficient of $2.9{\sim}3.6\;dB$ and the good phase difference of $91.2{\pm}2.9^{\circ}$ were obtained in broad frequency range of $75{\sim}100\;GHz$.

• Journal of Korean Society of Transportation
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• v.22 no.4 s.75
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• pp.147-158
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• 2004

A class of SWP(Stochastic Wane Propagation) models microscopically mimics individual vehicles' stochastic behavior and traffic jam propagation with simplified car-following models based on CA(Cellular Automata) theory and macroscopically captures dynamic traffic flow relationships based on statistical physics. SWP model, a program-oriented model using both discrete time-space and integer data structure, can simulate a huge road network with high-speed computing time. However, the model has shortcomings to both the capturing of low speed within a jam microscopically and that of the density and back propagation speed of traffic congestion macroscopically because of the generation of spontaneous jam through unrealistic collision avoidance. In this paper, two additional rules are integrated into the NaSch model. The one is SMR(Stopping Maneuver Rule) to mimic vehicles' stopping process more realistically in the tail of traffic jams. the other is LAR(Low Acceleration Rule) for the explanation of low speed characteristics within traffic jams. Therefore, the CA car-following model with the two rules prevents the lockup condition within a heavily traffic density capturing both the stopping maneuver behavior in the tail of traffic jam and the low acceleration behavior within jam microscopically, and generates more various macroscopic traffic flow mechanism than NaSch model's with the explanation of propagation speed and density of traffic jam.

• Journal of the Korean Society of Radiology
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• v.14 no.7
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• pp.947-956
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• 2020

The human body becomes vulnerable to various diseases due to deterioration in structure and function as it ages. In particular, changes in brain structure weaken the immune system against diseases such as vascular and metabolic neuropsychiatric diseases. In this study, we used a magnetic resonance imaging technique that allows non-invasive observation of brain structures and measurement of how the volumes of the brain, gray matter, white matter, and subcortical regions changes with aging in women aged 65 to 85 years. As a result of our investigation, we observed a significant linear decrease in subcortical regions with age. These results suggest that the changes due to aging in the brain structure area are closely related to neuropsychiatric diseases in old age, and can provide information in understanding the vulnerability of the brain in old age.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.3
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• pp.247-253
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• 2007

Determination of crack depth in filed using the self-calibrating surface wane transmission measurement and the cutting frequency in the transmission function (TRF) is very difficult due to variations of the measurement conditions. In this study, it is proposed to use the measured full TRF as a feature for crack depth assessment. A Principal component analysis (PCA) is employed to generate a basis of the measured TRFs for various crack cases. The measured TRFs are represented by their projections onto the most significant principal components. Then artificial neural networks (NNs) using the PCA-compressed TRFs is applied to assess the crack in concrete. Experimental study is carried out for five different crack cases to investigate the effectiveness of the proposed method. Results reveal that the proposed method can be effectively used for the crack depth assessment of concrete structures.

• Polymer(Korea)
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• v.26 no.3
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• pp.353-359
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• 2002

High intensity ultrasound has been applied to a series of poly(ethylene oxide) (PEO)/water systems having different molecular weights of PEO. Major interest was focused on the effect of ultrasonic wane on the melt viscosity chemical structure and thermal properties of PEO. The expected role of ultrasound used in this study was to generate macroradicals of PEO chains by the formation and subsequent collapse of bubbles. It was found that the melt viscosity and chemical structure of PEO change significantly depending on the sonication time. For the prolonged sonication, PEO chains were significantly degraded and new end groups were formed by the interplay of various radical species. When the molecular weight of PEO was relatively higher, the crystallization rate was decreased and the intensity of the melting peak was reduced.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.1 s.118
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• pp.55-64
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• 2007

In the built-up structure consisting of a stiff beam and a flexible plate, Grice showed that the plate behaves as an energy absorber in narrow frequency bands(called plate blocking effect). This paper deals with such beam-plate coupled structures, where the plate is an energy absorber and the excited beam is an energy path. It is found that such energy dissipation can occur in the relatively broad bands, if different stiffnesses are used in the rectangular plate. It was experimentally verified by Heckl that the energies in terms of one-third octave band averages transferred to the plate(or dissipated in the plate) increase for increased plate damping. This Paper, however, shows that the energy absorption suddenly reduces at the certain narrow frequency bands where the plate damping effect upon the coupled beam is maximum. Also, in order to minimize energy transfer through the beam in terms of one-third octave band averages, it is advantageous to increase the plate damping closer to the excitation point All these results are based on the wane method.