• Journal of Digital Contents Society
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• v.18 no.2
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• pp.383-392
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• 2017

This paper introduces a real-time 3D model generation system that can process in real time from multi-view image acquisition to image-based 3D model generation. This system describes how to collect, transmit, and manage the HD images input from 18 cameras and explain the background separation and smooth 3D volume model generation process. This paper proposes a new distributed data transmission and reception method for real-time processing of HD images input from 18 cameras. In addition, we describe a codebook-based background separating algorithm and a modified marching cube algorithm using perspective difference interpolation to generate smooth 3D models from multi-view images. The system is currently being built with a throughput rate of 30 frames per second.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.4
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• pp.9-17
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• 2012

In this paper, we show the memory effect of the high-power amplifiers for wied-band signals, present a compensation method for the nonlinearity combined with memory effect, and analyze its performance. For the modeling and the compensation of the nonlinear high-power amplifier with memory effect, we investigate the Volterra series model, the Wiener model, and the Hammerstein model. As a compensator scheme, we propose a digital feedforward technique. Compared to analog feed-forward scheme, the proposed scheme has better stability and adaptability to the environmental changes. It has a simpler structure than the conventional digital nonlinear compensation schemes. The result of computer simulations using ADS of the Agilent shows that spectral re-growth is suppressed by more than 20 dB, which amounts to at least 10 dB back-off. Considering the compensation performance, implementation complexity, and convergence rate, we could conclude the Wiener model is most suitable for the proposed scheme.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.5
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• pp.16-23
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• 2011

Muzzle flash based on gunnery is the target that has huge energy. So, gunnery target in a long range over xx km is distinguishable in the IR(infrared) images, on the other hand, is not distinguishable in the CCD images. In this paper, we propose the classification method of gunnery targets in a infrared images and in a long range. The energy from gunnery have an effect on varous pixel values in infrared images as a property of infrared image sensor, distance, and atmosphere, etc. For this reason, it is difficult to classify gunnery targets using pixel values in infrared images. In proposed method, we take the profile of pixel values using high performance infrared sensor, and classify gunnery targets using modeling GMM and shape of profile. we experiment on the proposed method with infrared images in the ground and aviation. In experimental result, the proposed method provides about 93% classification rate.

• Journal of the Korean Magnetics Society
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• v.8 no.4
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• pp.231-240
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• 1998

We investigated that the fabrication and reproducing signal characteristics of tri-layered magnetoresistance (MR) element for the high density magnetic thin film heads and sensors. Magnetoresistance curve of tri-layered MR element predicted by computer modeling was saturated above external field of -15 Oe~+22 Oe, and it was shifted to linearized region as large as 4 Oe. In the case of fabricated real device, magnetoresistance curve was saturated above external field of $\pm$15 Oe, and it was shifted to linearized region as large as 4 Oe. As shown in real device, MR response curve was in good agreement with the simulation results. As a result of experimental data of reproducing output signal in real device, it retained normal sinusoidal waveforms in 1~4 Oe external magnetic field. In this magnetic field region, the fabricated heads with tri-layered MR element can be operated with good reproduced characteristics. This will be beneficial to the use of efficient processes of manufacturing elements and the vacuum deposition techniques which control thin film properties.

• Journal of Radiation Protection and Research
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• v.28 no.1
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• pp.1-8
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• 2003

The periodic safety review of operational nuclear power plants requires that the plants should keep a well organized environmental monitoring program. The past records of environment monitoring data were analyzed. and the tritium concentrations of the samples in the surface and ground water around Kori site were measured. It was shown that the tritium concentrations around the Kori site were slightly higher than that of natural background. The change of background tritium concentration was estimated through a numerical modeling. Two different versions of 7 compartments model - the world and the northern hemisphere - defined in NCRP-62 were modeled for the global tritium cycling. The numerical solution of the model was obtained using a computer program, AMBER. The four cases of tritium source-terms into the atmosphere were considered. The results showed that the tritium concentration in the surface soil water was higher than that in sea water or surface stream water. Also, it was shown that the tritium produced by the interaction between cosmic rays and the gases were the major source of tritium, and the tritium produced by nuclear weapon test decreased considerably.

• The Journal of the Acoustical Society of Korea
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• v.20 no.1
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• pp.13-20
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• 2001

Adaptive digital filters with long impulse response such as acoustic echo canceller and active noise controller suffer from slow convergence and computational burden. Subband techniques and multirate signal processing have been recently developed to improve the problem of computational complexity and slow convergence in conventional adaptive filter. Any FIR transfer function can be realized as a serial connection of interpolators followed by subfilters with a sparse impulse response. In this case, each interpolator which is related to the column vector of Hadamard matrix has band-pass magnitude response characteristics shifted uniformly. Subband technique using Hadamard transform and decimation of subband signal to reduce sampling rate are adapted to system modeling and acoustic noise cancellation In this paper, delayless subband structure with nonuniform bandwidth has been proposed to improve the performance of the convergence speed without aliasing due to decimation, where input signal is split into subband one using tree-structured filter bank, and the subband signal is decimated by a decimator to reduce the sampling rate in each channel, then subfilter with sparse impulse response is transformed to full band adaptive filter coefficient using Hadamard transform. It is shown by computer simulations that the proposed method can be adapted to general adaptive filtering.

• 한국지구물리탐사학회:학술대회논문집
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• 1999.08a
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• pp.37-47
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• 1999

Among the geophysical exploration methods, electromagnetic (EM) survey must have the broadest range of instrumental systems and remarkable range of applications. There is a plethora of available techniques and instruments, and the depth of investigation and resolution are highly dependent on the particular systems used according to their operating frequency and source-receiver configuration. This diversity of EM systems, however, provides a wide range of instruments or methodologies to choose in order to select the most appropriate tool for the task in hand. This rather than being a disadvantage, would be a major strength of EM methods. Modern EM equipments are remarkably portable, considering their sophistication. Coupled with major advances in recent computer technology, accurate modeling and interpretation techniques are on the way of continuous development and upgrade which, in turn, make the EM methods to become much more heavily used, especially for engineering and environmental applications. We aim to provide a brief theoretical principles, survey techniques and case histories of some selected EM methods that can be applied to geotechnical and environmental problems in Korea.

• Journal of Service Research and Studies
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• v.4 no.1
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• pp.49-59
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• 2014

Context-aware computing is an emerging paradigm to achieve ubiquitous computing environments by enabling computer systems to understand their situational contexts. A context-aware system uses context to provide relevant information and services to the user depending on the user's task. In this paper, we propose an ontology-based context-aware modeling methodology that transmits low-level contexts acquired by directly accessing various sensors in the physical environments to high-level contexts. With these high-level contexts, context-aware application can provides proactive and intelligent services using ECA (Event-Condition-Action) rules. We implemented a home robot service in smart office environment.

• Korean Journal of Materials Research
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• v.11 no.3
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• pp.207-214
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• 2001

Silica glass is a core material for optical fiber in optical telecommunications, but its centrosymmetry eliminates the second order nonlinearity. But it is experimentally well known that the space charge polarization induces the Second Harmonic Generation (SHG) when a strong DC voltage is applied to silica glass for a long period of time with metal blocking electrodes. In this report, the results of a theoretical calculation of the nonlinear optical property caused by the space charge polarization, and a model of a numerical analysis to predict the small chance in nonlinear optical property as functions of time and space are provided. Assuming that amorphous silica is a solid state electrolyte and sodium ion is the only mobile charge carrier, 'Finite Difference Method' was employed for modeling of numerical analysis. The distributions of the concentration of sodium ion and electric field as functions of a normalized length of the specimen and a normalized applied voltage were simulated.

• Korean Journal of Construction Engineering and Management
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• v.10 no.6
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• pp.88-98
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• 2009

Construction industries have increasingly utilized Building information Modeling (BIM) technologies. Interoperability - the capability for BIM data to run from one computer application to another in the life cycle of a project has become one of the principal research areas. Enhancing interoperability inevitably requires information structures that are standardized throughout the construction industries. As a candidate of the data exchange standard, Industry Foundation Classes (IFC) has been developed and several researches recently performed to measure its richness of digital data exchange. But doubts have been brought up whether IFC meets a sufficient level of interoperability since the research result revealed a number of cases of information misrepresentation and loss. This research presents the lessons learned from the interoperability tests of three widely used 3D design applications including Graphisoft's Archicad, Autodesk's Revit, and Bentley's Bentley Architecture. One building's architectural and structural design data were modeled with the three tools and exchanged through IFC respectively for interoperability test.