• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2002.11a
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• pp.163-168
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• 2002

본 논문에서는 워터마크의 기본적인 요구사항인 비가시성(invisibility)을 유지하면서 강인함(robustness)을 최대로 하기 위해 워터마크를 삽입할 때 인간시각 특성(Human Visual System, HVS)을 이용한다. 특히, 주파수 마스킹(frequency masking), 공간 마스킹(spatial masking), 그리고 움직임 마스킹(motion masking)을 결합한 전역마스킹(global masking) 기법을 제안한다. 주파수 마스킹은 프레임을 DCT 변환한 후 주파수 민감도 표(frequency sensitivity table)를 이용해 위치 정보를 구한다. 공간 마스킹은 밝기(luminance) 및 윤곽선(edge) 정보를 이용해서 구하며. 움직임 마스킹은 이웃하는 프레임간의 움직임 변화를 이용하여 프레임간의 상관성을 고려한다. 본 논문에서는 키(key) 값에 의해 발생된 랜덤시퀀스와 로고의 배타적 논리합(exclusive OR)에 의해 결합된 워터마크를 전역 마스킹 결과에 따라 압축되지 않은 비디오 프레임에 직접 적용했으며, 실험을 통해 MPEG 부호화 및 재부호화 공격에 대해서 제안한 방법이 강인함을 확인했다.

• Journal of Energy Engineering
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• v.9 no.1
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• pp.37-40
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• 2000

An inverse problem is solved to determine the space-dependent thermal conductivity in one-dimensinoal time-dependent heat conduction medium with the data imposed and measured at the two end-points. The thermal conductivity is approximated as a linear combination of known functions with unknown coefficients and the unknowns are obtained by the governing and sensitivity equations using modified Newton-Raphson method. The estimated results are compared with exact thermal conductivities and it shows good agreements. This approach is expected to be used to estimate spatial composition of heat conduction medium.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.3
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• pp.587-599
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• 1996

In general fractal imge compression, each range block is approximated by a contractive transform of the matching domain block under the mean squared error criterion. In this paper, a distortion measure reflecting the properties of human visual system is defined and applied to a fractal image compression. the perceptual distortion measure is obtained by multiplying the mean square error and the noise sensitivity modeled by using the background brightness and spatial masking. In order to compare the performance of the mean squared error and perceptual distortion measure, a simulation is carried out by using the 512*512 Lena and papper gray image. Compared to the results, 6%-10% compression ratio improvements under improvements under the same image quality are achieved in the perceptual distortion measure.

• Fire Science and Engineering
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• v.3 no.2
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• pp.11-19
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• 1989

In this study, the independent variables are the floor plan configulation. The dependent variables are the occupant's egress behavior, especially spatial movement pattern, and life - safety performance of building. Fire events were simulated on single story of office building. Simulation run for allowable secaping thime(180 seconds) arbitrarily selected, and involved 48 occupants. The major findings Pre as follows. 1) Computer simulation model suggested in this study can be used as the Preoccupancy evaluation method of the life-safety performance for architectural design based on prediction of occupants' egress behavior in the levels of validity and sensitivity, 2) Sucess or failure in occupants' escape is determined by decreasing walking speed caused by jamming at exits or over crowded corridor, and increasing route length caused by running about in confusion at each subdivision and corridor. 3) In floor plan configuration which safe areas located at the extreme ends of the corridor, cellular floor planning have to be avoided preventing jamming and running about in confusion at overcrowded corridor.

• ETRI Journal
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• v.27 no.4
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• pp.377-384
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• 2005

We investigate near-infrared light (NIR) propagation in a model of an adult head using an extensive Monte Carlo (MC) simulation. The adult head model is a four-layered slab which consists of a surface layer, a cerebrospinal fluid layer, a gray-matter layer, and a white-matter layer. We study the effects of a refractive index mismatch on the model, calculating the intensity of detected light, mean flight time, and partial mean flight time of each layer for various refractive indices of the cerebrospinal fluid layer as functions of source-detector spacing. The Monte Carlo simulation shows that the refractive index mismatch presents very rich results including rapidly decaying intensity of detected light and a peak and cross-over in the partial mean flight time with source-detector spacing. We also investigate spatial sensitivity profiles at various source-detector spacings, discussing the index mismatch effect on the model.

• Proceedings of the Botanical Society of Korea Conference
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• 1987.07a
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• pp.117-132
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• 1987

Plants are inherited spatial and temporal coordination systems in their growth and differentiation processes which are precisely governed by the two interlocked control systems; autogenous and environmental. Looking into the overall course of plant development from molecular to organismal level, it can be comparable to a concerto for plant hormones, environmental stimuli and plant genomic orchestra conducted by an unidentified virtuoso. Some of the recent significant attempts to puzzle out the mystery of the life processes of plant development are briefly reviewed. The revolutionary advances in understanding the mystic processes are contemporarily achieved by the application of various molecular techniques. The characterization of plant genomes is now attained through recombinant DNA approaches, and the sensitive detection of specific gene products during the plant development is perimitted by the immunochemical procedures. However, along with the recognition of underlying molecular events such as developmental changes in gene expression and hormone-receptor interrelation associated with tissue sensitivity to hormones, more emphasis should be placed upon the physiological approaches of organismal level for the understanding the correlative systems of the developmental processes of plants as intact eukaryotic organisms.

• Proceeding of KASS Symposium
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• 2006.05a
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• pp.110-117
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• 2006

This study presents an effective stiffness-based optimal technique to consider floor rigid diaphragm action and a technique to evaluate the structural behavior characteristics and efficiency for tall shear wall outrigger system subject to horizontal loads. To this end, isoparametric plane stress element with rotational stiffness is used for shear wall element and stiffness gradient is calculated. Also, the approximation concept to solve effectively the large scaled problems, member grouping technique and resizing technique are considered. To verify the effectiveness and usefulness of this technique, the efficient evaluation method for three types of 50 story model with core and outrigger system is presented.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.69.1-69.1
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• 2012

We present a comprehensive study of star-forming regions and young star clusters in M33. We use GALEX far-UV and near-UV imaging to detect these young stellar populations tracing recent star formation across the disk of M33. The GALEX imaging, combining deep sensitivity and entire coverage of the galaxy, provides a complete view of the recent star formation in M33 and its variation with environment throughout the galaxy. We discuss variation of various properties (e.g., age, mass, spatial distribution) of star-forming regions and young star clusters in M33 which allow to provide constraints of recent star formation history of this galaxy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.4
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• pp.848-854
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• 1996

Many image display devices allow only a limited number of colors to be simultaneously displayed. in disphaying of natural color image using color palette, it is necessary to construct an optimal color palette and the optimal mapping of each pixed of the original image to a color from the palette. In this paper, we proposed the clustering algorithm using local region block centered one color cluster in the prequantized 3-D histogram. Cluster pairs which have the least distortion error are merged by considering distortion measure. The clustering process is continued until to obtain the desired number of colors. The same as the clustering process, original color value. The proposed algorithm incroporated with a spatial activity weighting value which is reflected sensitivity of HVS quantization errors in smoothing region. This method produces high quality display images and considerably reduces computation time.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.241-242
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• 2019

This technology is a water leak repair technology using composite materials of concrete structures that block leakage of structures by injecting rapid microcement into the face of underground concrete to block water and injecting flexible glycidylacrylate. Rapid micro cement system repair materials are mixed with fine fibers to improve the flexural sensitivity of the material and to form a layer that blocks stabilized water at the back of the structure by allowing rapid and tight spatial filling during injection with high cohesion The glycidylacrylate repair material can control the expansion rate, and the external stress also has the characteristic that the form of the material is not destroyed or separated, which can also be applied to vibrating induced structures that produce repetitive fatigue loads, and has an effective durability in saline, alkali, acid (chloric acid, sulfuric acid, nitric acid).