• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.319-324
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• 2001

An anatomical head and a multi-layered spherical head with a half-wave handset antenna have been analysed and compared using the Finite-Difference Time-Domain (FDTD) and the Eigenfuntion Expansion Method (EEM), respectively. The analysis shows that results from a simple spherical head with a half-wave antenna can be used to predict the main antenna radiation patters as well as estimates of the peak SAR in a handset user's head. Various representative design data are presented using a six-layered spherical head with a half-wave antenna at 900 MHz

• Proceedings of KOSOMES biannual meeting
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• 2017.04a
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• pp.264-264
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• 2017

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.2
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• pp.106-121
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• 2020

In order to make harbor outskirt facilities robust using the reliability-based design, probabilistic models of wave heights at varying stage of shoaling process optimized for Korean sea waves are prerequisite. In this rationale, we numerically simulate the nonlinear shoaling process of random waves over the beach with a sandbar at its foreshore. In doing so, comprehensive numerical models made of spatially filtered Navier-Stokes Eq., LES [Large Eddy Simulation], dynamic Smagorinsky turbulence closure were used. Considering the characteristics of swells observed at the east coast of Korean Peninsula, random waves were simulated using JONSWAP wave spectrum of various peak enhancement coefficients and random phase method. The coefficients of probabilistic models proposed in this study are estimated from the results of frequency analysis of wave crests and its associated trough detected by Wave by Wave Analysis of the time series of numerically simulated free surface displacements based on the threshold crossing method. Numerical results show that Modified Glukhovskiy wave height distribution, the most referred probabilistic models at finite water depth in the literature, over-predicts the occurring probability of relatively large and small wave heights, and under predicts the occurrence rate of waves of moderate heights. On the other hand, probabilistic models developed in this study show vary encouraging agreements. In addition, the discrepancy of the Modified Glukhovskiy distribution from the measured one are most visible over the surf zone, and as a result, the Modified Glukhovskiy distribution should be applied with caution for the reliability-based design of harbor outskirt facilities deployed near the surf-zone.

• Korean Institute of Interior Design Journal
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• v.25 no.2
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• pp.59-69
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• 2016

This study aimed to understand the importance of applying finishing materials into interior space, and to add meaning to the creation of functional space, associated interior finishing materials with brain science. To achieve this purpose, brainwave(EEG) experiment was conducted. The brainwave appearing when sensing the surface of interior finishing materials with hands was measured. The locations of the electrode were FP1, FP2, F3, F4, C3, C4, P3, P4, O1, O2, F7, F8, T3, T4, T5, T6, CZ, FZ, and PZ and in addition to these, AFZ was added. Eight(8) kinds of finishing materials: metallic material, film paper, lumbar, stone, glass, silk wallpaper, fabric, and paint were used to measure '${\alpha}$-wave against ${\beta}$ wave.' As a result, it was found that the most activated finishing material in term of relaxation was film paper, followed by metallic, glass, paint, fabric, stone, lumbar, and silk wallpaper. To explain in light of this, (1) '${\alpha}$-wave against ${\beta}$ wave' was the most activated at ch1-FP1 and ch2-FP2, and at ch17-AFZ and ch19-FZ, which indicated that metopic-prefrontal lobe showed the highest activation in relaxation. Film paper, among the finishing materials, showed the highest increase in relaxation. (2) In general, '${\alpha}$-wave against ${\beta}$ wave' relaxation was inhibited at ch13-T3 and ch14-T4, and at ch15-T5 and ch16-T6 and the arousal in the temporal lobe was prominent. Silk wallpaper, among the finishing materials, showed the highest arounsal effect. As a result of measuring the superficial touch on the silk wallpaper, which was regarded as the most rough material among the eight finishing materials, the arousal effect of ${\alpha}$-wave against ${\beta}$-wave, among the brainwave characteristics, was found to be the highest. (3) to judge from the scope of this experiment regarding the tactile sensation over the finishing materials, it is considered that the brainwave reaction sometimes appeared contrastive depending on whether the surface was smooth or rough and there also appeared a difference in relaxation and arousal reaction of the brainwave depending on whether the surface was hot or cold, but the sensation on the surface texture was often evaluated differently depending on who you were. For this reason, this study has some limitations.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.5
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• pp.203-216
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• 2021

Analyzing various wave interactions with oscillating wave surge converters (OWSC) is essential because they must be operated efficiently under a wide range of wave conditions and designed to extract optimal wave energy. In the conceptual design and development stage of OWSC, numerical analysis can be a good alternative as a design tool. This study performed a numerical analysis on the behavioral characteristics of the inverted triangle flap against the incident waves using open source CFD to examine the essential behavioral attributes of OWSC. Specifically, the behavioral characteristics of the structure were studied by calculating the free water surface displacement and the flap rotation angle near the inverted triangular flap according to the change of the period under the regular wave conditions. By comparing and examining the numerical analysis results with the hydraulic model experiments, the validity of the analysis performed and the applicability in analyzing the wave-structure interactions related to OWSC was verified. The numerical analysis result confirmed that the hydrodynamic behavior characteristic due to the interactions of the wave and the inverted triangle flap was well reproduced.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.4
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• pp.274-279
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• 2015

Wave data acquired over eleven years near Sokcho Harbor located in the central area of the east coast were analyzed using spectral method and wave-by-wave analysis method and its major wave characteristics were examined. Significant wave heights were found to be high in winter and low in summer, and peak periods were also found to be long in winter and short in summer. The maximum significant wave height observed was 8.95 m caused by the East Sea twister. The distributional pattern of the significant wave heights and peak periods were both fitted better by Kernel distribution function than by Generalized Gamma distribution function and Generalized Extreme Value distribution function. The wave data were compiled to subdivide the wave height into intervals for each month, and the cumulative occurrence rates of wave heights were calculated to be utilized for the design and construction works in nearby construction works.

• Journal of Ocean Engineering and Technology
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• v.35 no.1
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• pp.82-90
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• 2021

Owing to the advantages of assuring the best views and seawater exchange, submerged breakwaters have been widely installed along the eastern coast of Korea in recent years. It significantly contributes to promoting the advancement of shorelines by partially inhibiting incident wave energy. Observations were carried out by a pressure-type wave gauge in the Bongpo Beach to evaluate the coefficients of wave transmission via a submerged breakwater, and the results obtained were compared with those of existing conventional equations on the transmission coefficient derived from hydraulic experiments. After reviewing the existing equations, we proposed a transmission coefficient equation in terms of an error function. Although it exhibited robust relationships with the crest height and breaking coefficient, deviations from the observed data were evident and considered to be triggered by the difference in the incident wave climate. Therefore, in this study, we conducted a numerical experiment to verify the influence of wave period on the coefficients of wave transmission, in which we adopted a parabolic-type mild-slope equation model. Consequently, the deviation from calculated results appears to practically cover all deviation range in the observed data. The wave period and direction of the incident wave increased, the transmission coefficient decreased, and the wave direction was determined to demonstrate a relatively significant influence on the transmission coefficient. It was inferred that this numerical study is expected to be used practically in evaluating the design achievement of the submerged breakwater, which is adopted as a countermeasure to coastal beach erosion.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.223-225
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• 2008

In this study. we propose a wide bandwidth surface acoustic wave (SAW) motor by design of Inter Digital Transducer (IDT). SAW motor has several benefits compared with preexisted actuator. But it has narrow bandwidth, which causes the lower performance. To widen the bandwidth, the change of IDT structure was proposed, which is slanted IDT and since function apodization. The frequency responses were compared original uniform IDT and changed IDT. And the time responses were compared original uniform IDT and changed IDT. As a result, the feasibility of wide bandwidth SAW motor was certified.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.6
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• pp.1141-1147
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• 2012

Electromagnetic analysis to design unclonable PUFs with frequency-dependant materials with Debye dispersion was considered. To simulate FDTD calculations consider that 1-D problem of pulsed plane wave traveling in free space normally incident on air-silicon material interface on dielectric substrate. The pulse traveling wave at a vacuum-medium interface was reflected, and transmitted wave was dissipated. As a result, 1-D PUF modeling with Debye dispersion on dielectric substrate structure can be applied and FDTD calculation for PUF modeling is a good approximation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.1 no.1
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• pp.95-106
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• 1995

The small-waterplane-area-twin-hull(SWATH) ship has been recognized as a promising high performance ship because of her superior seakeeping characteristics and large deck area for various operations compared to the conventional monohull ship. significant advances in analytical technics for the prediction of the ship motions, wave loads and structural responses, structural fatigue and its prediction, and hull vibration for ship motions, wave loads and structural responses, structural fatigue and its prediction, and hull vibration for SWATH ship have been much developed during the last twenty years. Based on these developments in technology an integrated computational procedures for prediction wave loads and structural responses can be used to get a accurate results. But the major problem of SWATH ship's structural design is the accurate prediction of structural responses by the maximum critical loads likely to be experienced during the life of SWATH. To get a easier and safer computational procedures and the analytical approach for determining the accurate structural responses, a case study has been presented through the project experienced.