• Journal of Korea Water Resources Association
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• v.32 no.5
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• pp.565-577
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• 1999

The geometric patterns of a stream network in a drainage basin can be viewed as a "fractal" with fractal dimensions. Fractals provide a mathematical framework for treatment of irregular, ostensively complex shapes that show similar patterns or geometric characteristics over a range of scale. GIUH (Geomorphological Instantaneous Unit Hydrograph) is based on the hydrologic response of surface runoff in a catchment basin. This model incorporates geomorphologic parameters of a basin using Horton's order ratios. For an ordered drainage system, the fractal dimensions can be derived from Horton's laws of stream numbers, stream lengths and stream areas. In this paper, a fractal approach, which is leading to representation of a 2-parameter Gamma distribution type GIUH, has been carried out to incorporate the self similarity of the channel networks based on the high correlations between the Horton's order ratios. The shape and scale parameter of the GIUH-Nash model of IUH in terms of Horton's order ratios of a catchment proposed by Rosso(l984J are simplified by applying the fractal dimension of main stream length and channel network of a river basin. basin.

• Journal of Korea Water Resources Association
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• v.44 no.2
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• pp.145-156
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• 2011

Two dimensional numerical model of high-order accuracy is developed to analyze complex flow including transition flow, discontinuous flow, and wave propagation to dry bed emerging at natural river flow. The bed slope term of two dimensional shallow water equation consisting of integral conservation law is treated efficiently by applying quasi-steady wave propagation scheme. In order to apply Finite Volume Method using Fractional Step Method, MUSCL scheme is applied based on HLL Riemann solver, which is second-order accurate in time and space. The TVD method is applied to prevent numerical oscillations in the second-order accurate scheme. The developed model is verified by comparing observed data of two dimenstional levee breach experiment and dam breach experiment containing structure at lower section of channel. Also effect of the source term is verified by applying to dam breach experiment considering the adverse slope channel.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.17 no.1
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• pp.47-54
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• 2005

A method has been developed, which can be handled easily and economically for inputting depth data of complex bathymetry and enourmous tidal flats such as Mokpo coastal zone. The method is applied to Chungkye Bay, and some hydrodynamic features related with tidal flat are analyzed. Tidal amplification by construction of the sea-dike and sea-walls had been detected not only near Mokpo Harbor but also at Chungkye Bay which is connected with Mokpo Harbor by a narrow channel. This brings about the increase of tidal flat area, which makes the ebb dominance at Chungkye Bay more seriously. This pronounced ebb dominance with the increase of tidal discharge at the channel between Chungkye Bay and Mokpo Harbor, which results in deepened ebb dominance near Mokpo Harbor as well.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1B
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• pp.114-124
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• 2002

In this paper, we proposed the image-based 3D ray tracing indoor propagation model using a patch scattering model for fading analysis of indoor propagation environments. An image-based 3D ray tracing technique is mainly used, which allows the rapid generation of the complex channel impulse response for any given location and polarization of transmitter and receiver. Due to the site specific nature of indoor environment, we took into account the location and the electrical properties of individual walls and objects such as windows, doors and plaster board in our propagation model. Besides, the 3D radiation beam-patterns and polarizations of arbitrary antennas were considered, and using patch scattering model we can consider the change of the polarization due to the scattering from the various indoor objects, like desks, chairs and etc. the are almost impossible to be modeled with the basic image-based ray tracing method. The model will predict the impulse response, the rms delay spread, the fading characteristics of the channel and performances of the polarization diversity schemes.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.7
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• pp.46-56
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• 2002

In this paper, we describe a hardware-software co-verification methodology and environment in developing a mobile station modem chip for cdma2000 1x which is one of the 3rd generation mobile communication standards. By constructing an efficient co-verification environment for a register-transfer-level hardware model and a physical-layer software model combining a channel link simulator and a versatile test-bench, we can drastically reduce both time and cost for developing a complex three-million-gate class system integrated circuit.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.9
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• pp.901-905
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• 2012

We present an electroporation and viability monitoring chip for lung cancer cells in a single channel with multiple electric field zones. Previous electroporation chips utilized multiple microchannels or electrodes to form multiple electric fields, thus resulting in complex structures. However, the present chip can generate multiple electric fields in a single stepwise microchannel between a pair of electrodes, thus achieving the analysis of both cell electroporation and viability with a simple structure. We demonstrate that the electric field of 0.4 kV/cm results in a maximum percentage of $51.4{\pm}3.0%$ and $26.6{\pm}0.7%$ of viable and electroporated human lung cancer cells, H23 and A549, respectively. The present chip has potential for use in integrated cell chips for transfection studies.

• Journal of Korean Society for Quality Management
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• v.45 no.3
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• pp.503-520
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• 2017

Purpose: In the near future, it is expected that UGV(unmanned ground vehicle) will be put into battle due to IT technology and unmanned technology development. In this study, we analyze the combat effectiveness considering communication effect where complex combat information and commands are transmitted. Methods: We use ABM(agent-based modeling) and wireless channel module which provides sophisticated communication effect through geographic information and UGV performance. And UGV combat simulation using wireless channel module is used to grasp the combat effectiveness according to the number of packets, which is a unit for storing all information and commands having high complexity. Results: The result of this study is to derive the optimal number of packets which does not decrease the combat effectiveness and the number of lost tanks. The number of packet increases, the survival ratio of our tanks are decreased. Conclusion: In this study, we reveal that the communication success or failure could affect the combat effectiveness. Also, it helps develope the standard communication protocol between UGVs and could be applied to analyze the cost effectiveness analysis in UGV combat environment.

• Progress in Superconductivity
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• v.5 no.2
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• pp.98-104
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• 2004

We analyzed a noise-sensitivity profile of a specific SQUID sensor system for the localization of brain activity. The location of a neuromagnetic current source is estimated from the recording of spatially distributed SQUID sensors. According to the specific arrangement of the sensors, each site in the source space has different sensitivity, that is, the difference in the lead field vectors. Conversely, channel noises on each sensor will give a different amount of the estimation error to each of the source sites. e.g., a distant source site from the sensor system has a small lead-field vector in magnitude and low sensitivity. However, when we solve the inverse problem from the recorded sensor data, we use the inverse of the lead-field vector that is rather large, which results in an overestimated noise power on the site. Especially, the spatial sensitivity profile of a gradiometer system measuring tangential fields is much more complex than a radial magnetometer system. This is one of the causes to make the solutions of inverse problems unstable on intervening of the sensor noise. In this study, in order to improve the localization accuracy, we calculated the noise-sensitivity profile of our 40-channel planar SQUID gradiometer system, and applied it as a normalization weight factor to the source localization using synthetic aperture magnetometry.

• BMB Reports
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• v.44 no.11
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• pp.719-724
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• 2011

The $Sec61{\alpha}$ subunit is the core subunit of the protein conducting channel which is required for protein translocation in eukaryotes and prokaryotes. In this study, we cloned a $Sec61{\alpha}$ subunit from Penicillium ochrochloron ($PoSec61{\alpha}$). Sequence and 3D structural model analysis showed that $PoSec61{\alpha}$ conserved the typical characteristics of eukaryotic and prokaryotic $Sec61{\alpha}$ subunit homologues. The pore ring known as the constriction point of the channel is formed by seven hydrophobic amino acids. Two methionine residues from transmembrane ${\alpha}$-helice 7 (TM7) contribute to the pore ring formation and projected notably to the pore area and narrowed the pore compared with the superposed residues at the corresponding positions in the crystal structures or the 3D models of the $Sec61{\alpha}$ subunit homologues in archaea or other eukaryotes, respectively. Results reported herein indicate that the pore ring residues differ among $Sec61{\alpha}$ subunit homologues and two hydrophobic residues in the TM7 contribute to the pore ring formation.

• Journal of Korea Water Resources Association
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• v.41 no.6
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• pp.575-585
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• 2008

It is essential to obtain accurate and highly reliable streamflow data for water resources planning, evaluation and management as well as design of hydraulic structures. A new discharge computation method proposed in this research uses Chiu's velocity distribution and estimation of maximum velocity. This method shows acceptable channel discharges comparing these by the exiting velocity-area method. When velocity-area method is used, it is required to observe velocities at every specified point and vertical line using a velocity meter like Price-AA. If the method proposed in this research, is used, however it is not necessary to observe all point velocities needed in the velocity-area method. But this method can not be applied for the cases of very complex and strongly asymmetric channel cross-sections because Chiu's velocity distribution using entropy concept may be quite biased from that of natural rivers.