• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.06a
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• pp.211-212
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• 2018

본 논문에서는 프레넬 변환의 다양한 파라미터를 조절하여 홀로그램에 적용한 뒤 비디오 코딩을 이용한 압축을 수행하고 이에 대한 효율을 분석하였다. 공간상의 재생되는 객체의 실제 위치와 프레넬 변환에서의 전파된 거리의 관계, 참조된 파의 파장, 홀로그램 디스플레이 장치의 화소의 크기에 대한 분석을 수행하였다. 프레넬 변환 파라미터 중 참조파의 파장에 대한 영향은 미비하지만 변환 거리 및 화소의 크기에는 압축 효율에 큰 영향을 미치는 것을 확인하였다.

• Economic and Environmental Geology
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• v.44 no.3
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• pp.229-238
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• 2011

S-wave, which provides lithology and pore fluid information, plays a key role in estimating gas-hydrate saturation. In general, P- and S-wave velocities increase in the presence of gas-hydrate and the P-wave velocity decreases in the presence of free gas under the gas-hydrate layer. Whereas there are very small changes, even slightly increases, in the S-wave velocity in the free gas layer because S-wave is not affected by the pore fluid when propagating in the free gas layer. To verify those velocity properties of the BSR (bottom-simulating reflector) depth in the gas-hydrate prospect area in the Ulleung Basin, P- and S-wave velocity profiles were derived from multi-component ocean-bottom seismic data which were acquired by Korea Institute of Geoscience and Mineral Resources (KIGAM) in May 2009. OBS (ocean-bottom seismometer) hydrophone component data were modeled and inverted first through the traveltime inversion method to derive P-wave velocity and depth model of survey area. 2-D multichannel stacked data were incorporated as an initial model. Two horizontal geophone component data, then, were polarization filtered and rotated to make radial component section. Traveltimes of main S-wave events were picked and used for forward modeling incorporating Poisson's ratio. This modeling provides S-wave profiles and Poisson's ratio profiles at every OBS site. The results shows that P-wave velocities in most OBS sites decrease beneath the BSR, whereas S-wave velocities slightly increase. Consequently, Poisson's ratio decreased strongly beneath the BSR indicating the presence of a free gas layer under the BSR.

• Journal of the Korean Society for Marine Environment & Energy
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• v.7 no.4
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• pp.207-215
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• 2004

Recently, securing a vast land in the land region becomes more difficult and efforts to seek its alternation in the sea area have been increased. As a consequence, the coastal region has been faced to extensive beach erosion problems. In planning offshore structures such as artificial islands, it is necessary to forecast the influence of the structure construction exerting on the beach erosion of the adjacent coast. In the present study, the sediment movement pattern behind offshore structure was examined through a series of three dimensional movable bed experiments, so as to develop the numerical model which forecasts morphological change including beach erosions. The experimental results reveal that the sediment movement patterns of the beach line side and the depth region are separated at a certain boundary line. In details, at the beach side including swash zone the sediment movement becomes dominant, which is governed by a relation between depth contours and incident wave directions, while at the depth region the bed load and suspended load due to the orbit motion of waves are carried by nearshore currents, and both movements are clearly separated at a specified boundary that is related to partial standing wave from the beach. It is expected that these results can be effectively used for verification of a numerical model on morphological change of the coast.

• Sleep Medicine and Psychophysiology
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• v.17 no.2
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• pp.91-99
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• 2010

Objectives: Deficit schizophrenia (DS) constitutes a disease separate from non-deficit schizophrenia (NDS). The aim of the current study was to compare the quantitative EEG and low resolution electromagnetic tomography (LORETA) imaging between DS and NDS. Methods: This study was performed by 32 channels EEG for 42 schizophrenia patients who we categorized into DS and NDS using proxy instrument deficit syndrome (PDS). We performed the absolute power spectral analyses for delta, theta, alpha, low beta and high beta activities. We compared power spectrum between two groups using Independent t-test. Partial correlation test was performed with clinical parameters. Standardized LORETA (sLORETA) was used for comparison of cortical activity, and statistical nonparametric mapping (SnPM) was applied for the statistical analysis. Results: DS showed significantly increased delta and theta absolute power in fontal and parietal region compared with NDS (p<0.05). Power spectrum showed significant correlation with 'anergia' and 'hostility/suspiciousness' subscale of brief psychiatric rating scale (BPRS)(p<0.05). sLORETA found out the source region (anterior cingulate cortex/limbic part) that delta activity was significantly increased in DS (p=0.042). Conclusions: DS showed different cortical activity compared with NDS. Our results may suggest QEEG and LORETA could be the marker in differentiating between DS and NDS.

• The Journal of Engineering Geology
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• v.4 no.2
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• pp.187-206
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• 1994

Through a computer model study, optimum system configuration and field parameters were determined for high-resolution marine reflection surveys. Characteristics of far-field signatures were analysed in both time and frequency domains for the six individual R/V Onnuri. The analysis shows that the cluster fired at the depth of 2m below the sea surface generates the most ideal far-field signatures among the above seismic sources. Compared with the 96-channel streamer on the R/V Onnuri, the 12-channel streamer is suitable for shallow reflection profiling due to its high resolution both in the vertical and horizontal directions despite its lower signal-to-noise ratio. Considering factors including target depth, frequency range, airgun volume, number of recording channels, and capacity of compressors, optimum values for record length, sample period, and shot interval are believed to be is, 1ms, and 3.125m or 6.25m, respectively.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.1
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• pp.105-114
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• 1993

The ciculation due to bottom density current produced by a dense inflow into a small reservoir is analysed by numerical scheme. Before the front of the density current arrives at the downstream end, the mixing in the reservoir is mainly caused by the anticlockwise vortex formed at the downstream of plunging point along the movement of bottom density current. Upon the arrival of the front of the density current at the downstream end an internal surge is created through an internal hydraulic jump. With repeated propagation of the internal surge back and forth the mixing in the reservoir is progressed and the thickness of dense layer is increased upward. The dilution of the overflow at downstream end is found to depend on inflow densimetric Froude number, reservoir length and elapsed time. The time required for the overflow to attain a specified dilution increases as reservoir length increases and Fre decreases.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.3
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• pp.599-606
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• 1988

Structures of interfacial waves in nearly-horizontal countercurrent stratified air-water flow have been measured by means of a needle contact method. Based upon a statistical analysis for the liquid film distribution, statistical properties of the waves such as mean film thickness, mean wave amplitude and rms value of the wave fluctuation have been calculated. The results show that the film distribution can be described by a Gaussian probability density function for the three-dimensional wave regime. It is also indicated that the mean film thick ness and the rms value of the wave fluctuation increase as gas and liquid flow rates are increased in countercurrent two-phase flow. The dimensionless intensity of the wave fluctuation may be regarded as a function of the Froude number and the dimensionless mean film thickness.

• Journal of the Korean Society for Nondestructive Testing
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• v.13 no.4
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• pp.18-24
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• 1994

This paper discusses experimental results obtained by the potentiality of cross-correlation function as a tool for analyzing propagation of wave in an aluminum and a woven glass fiber composite. Each propagated wave has its own characteristic time delay, and examination of the cross-correlation of input and output signal give the most proper wave velocity and significant path. Using the above distinctive features, we observed the propagation velocity for the aluminum alloy and a woven glass fiber composite more acurately and easily then the common methods. The fiber locations of this composite also determined by the basis of these results.

• Journal of Korean Medical classics
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• v.20 no.4
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• pp.65-79
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• 2007

재한의학적착자상상견적"의자의야"저개어구(在한의學的着者上常見的"의者意也"저개語句), 파의학이론적신비성(把의學理論的神秘性), 치료방법적영활성(治료方法的영活性), 의가적오성간주'의'(의家的悟性看做'意'). 환구화래설(換句話래說), 한의학적운치포괄"가이의회(한의學的운致包括"可以意회), 난우언전"적감각(難于言전"的感覺). 수연의학기자연과학우실용기술(수然의學旣自然科學又실用技술), 환미비소우의가이'의'여하구축학문적연구(환未비소于의家以'意'如何구筑學問的硏究). 여금종각개각도평가전통과학기술화문화적시후(如今종各개角度評가전統科學技술和文化的시候), 서방과학기술재지구상번성이보급이후(西方科學技술在地球上繁盛而普及以后), 유일한의학잉연유불쇠퇴적생명력(唯一한의學仍然有不衰退的生命力), 저취시양인문표시경희(저就是양人們表示倞喜). 여차동시인문안조서방과학적시각화표준(여此同시人們按照西方科學的시角和표准), 파유일지탱생명력적한의학부단지관찰(把唯一支撑生命力的한의學不단地관察), 검사(檢査), 평가(評價), 요구(要求), 개조(改造). 저양적정황하(저양的情況下), 대표착"의자의야"적한의학불유득수도료허다견책(代表着"의者意也"的한의學不由得受到了許多遣責). 대우연구한의학래설(대于硏究한의學래說), 응해소주여하이해고대의가전래적저구화(應該소注如何理解古代의家전래的구句和). 통과요육군적연구등(通과寥育群的硏究等), 논자요분석이정리(論者要分析而整理), 매시기"의자의야"적다양포함화표연형식(每時基"의者意也"的多양包含和表演形式).

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.10 no.4
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• pp.174-186
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• 1998

A Galerkin's finite element model incorporating infinite elements for modeling of radiation condition at infinity has been developed, which is based on an extended mild-slope equation. To illustrate the validity and applicability of the present model, the example analyses were carried out for a resonance problem in the rectangular harbor of Ippen and Goda (1963) and for wave transformations over circular shoals of Sharp (1968) and Chandrasekera and Cheung (1997). Comparisons with the results obtained by hydraulic experiments and hybrid element method showed that the present model gives very good results in spite of the rapidly varying topography. Numerical experiments were also performed for wave transformations over a circular concave well which may be an alternative to conventional wave barriers.