• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2206-2208
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• 1998

The modular Lateral Information Propagation Networks(LIPN) has been designed. The LIPN has shown to be useful for interpolation of information[3]. The problem is the fact that only the small number of nodes can be implemented in a IC chip with the circuit VLSI technology. The proposed modular architecture is for enlarging the neural network through inter module connections. For such inter module connections, the host(computer or logic) mediates the exchange of information among modules. Also border nodes in each module have capacitors for temporarily retaining the information from outer modules. The LIPN with $4{\times}4$ modules has been designed and simulation of interpolation with the designed LIPN has been done.

• Korean Journal of Agricultural Science
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• v.23 no.2
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• pp.233-241
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• 1996

The mechanical properties of biological materials depend on numerous factors. The majority of these relationships are still unknown today, especially with regard to their quantitative characteristics. The reason is that biological materials constitute biomechanical systems of very complex construction, whose behavior cannot be characterized by simple physical constants, as for example can that of engineering materials. The objectives of this investigation were to determine the compression creep and recovery properties of rice stalks at various levels of applied load The compression creep and recovery behavior of the rice stalk could be predicted precisely by rheological model which approached closely to the measured values. But the coefficients of the Burgers recovery model were different from those of the creep model. The Steady state creep behavior occurred at the higher level of force and the logarithmic creep behavior occurred at the lower level of force. The mechanical model being expected the creep behavior in relation with the level of applied load, which was well explained that the rice stalk might be visco-elastic material.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.4
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• pp.297-304
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• 1996

The purpose of this study is to observe the applicability of parabolic mild-slope equations allowing relatively large angles of wave propagation based on the use of a Pade approximant or minimax approximation and also the applicability of the models with nonlinearity of diffracted waves in the shadow zone behind coastal structures. To accomplish these objectives, numerical solutions are obtained from the above parabolic models and are compared with the results from Watanabe and Maruyama's(1984) hydraulic model test on the wave field with an impermeable detached breakwater. From this study, it is found that computed wave heights increase for the nonlinear results in comparison to the linear results due to the increased diffraction effect across the geometric shadow boundary. The model with a larger aperture with respect to the principal direction was found to spread laterally to a much greater degree where spreading angle (diffraction effect) is relatively large. which causes a distortion in the overall results due to the error accumulated by the approximation of wave length.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.10
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• pp.973-978
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• 2010

In this paper, we studied the shimmy phenomena of an aircraft nose landing gear considering free-play. Shimmy is a self-excited vibration in lateral and torsional directions of a landing gear during either the take-off or landing. This phenomena is caused by a couple of conditions such as low torsional stiffness of the strut, friction and free-play in the gear, wheel imbalance, or worn parts, and it may make an aircraft unstable. Free-play non-linearity is linearized by the described function for a stability analysis in a frequency domain, and time marching is performed using the fourth-order Runge-Kutta method. We performed the numerical simulation of the nose landing gear shimmy and investigated its linear and nonlinear characteristics. From the numerical results, we found limit-cycle-oscillations at the speed under linear shimmy speed for the case considering free-play and it can be concluded that the shimmy stability can be decreased by free-play.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.565-572
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• 1994

Consolidation behavior on soft clay was investigated by using one- and two-dimensional analysis based on original and modified one dimensional consolidation theory. For the analytical model, the embankment was simulated by applying single- or multi-surcharge loading to the surface of soft clay. Based on the results obtained, it was found that the predicted settlement by one dimensional consolidation theory was most of the time higher than the observed one at the mid- and especially lateral-zone of embankment. When compared with two dimensional analysis, the result of modified one dimensional consolidation analysis showed almost similar trend to the observed one. There fore even in case where proper selection of soil parameters, one dimensional consolidation theory like as modified one dimensional consolidation theory could be suggested due to its convenience.

• Journal of the Korean Institute of Gas
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• v.18 no.6
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• pp.1-6
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• 2014

This study is based on a investigation regarding the evaporation rate of a volatile liquid(methanol, tetrahydrofuran, xylene) according to changes of the temperature and wind. The weight of a volatile liquid was standardized to 24 g and the mixture was formed with the same weight ratio. In order to discover about the effect of the wind velocity, small fan was installed at 10 cm above the entrance and 30 cm away in the direction of the cylinder. The effect of the wind velocity was tested at 0 m/s, 1.63 m/s, 2.03 m/s respectively and the effect of the temperature on the volatile liquid was experimented at the temperature of $21^{\circ}C$, $32^{\circ}C$, $52^{\circ}C$ in the constant temperature water base. As a result, in case of Xylene, the evaporation rate of the tetrahydrofuran and methanol showed 1.4 mg/min, 19.8 mg/min and 10.2 mg/min respectively. Also, the effect of the evaporation rate on the temperature of the volatile liquid and on the velocity of wind was shown to be very sensitive. At the same time, the evaporation rate of the mixture showed large difference compared to that of the single volatile liquid.

• Journal of Biomedical Engineering Research
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• v.10 no.3
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• pp.253-260
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• 1989

The time domain methods of estimating the attenuation coefficient are generally based on the analysis of statisical properties of the reflected echoes form an attenuating medium. Hence, it is often required to have a large number of data samples in order to obtain a statistically stable estimation result. In the attenuation estimation problem, this means that many different speckle patterns are required in the spatial resolution volume of an attenLlation image. In this paper, by using the fact that the speckle pattern Is sensitive to the point spread function of the ultrasound beam, we suggest a method to generate the statiscally uncorrelated or slightly correlated data samples in a given region by rotating a linear transducer and carrying out lateral scans for all rotating angles. This technique is applied to the entropy method for attenuation estimation proposed recently by the authors where the performance is verified by experiments using a tissue equivalent phantom.

• Journal of Korea Water Resources Association
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• v.41 no.4
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• pp.395-404
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• 2008

It is important to understand the complex, various migration features of the alluvial channels for river engineering. In this study, the morphological changes and migration features of alluvial channels were investigated by analyzing the aerial photographs of active channels between 1972 and 2004 in Hapyeong Intake Station, Nakdong river. The lower channels were migrated from left bank to right bank and showed the features of braided channel in 2004. The instability of lower channels was increased due to the increased channel slope and width. The sinuosity of lower channels was decreased with time. As time increased, the increasing rate of lower channel and lateral migration rate were decreased. As a result of meso-scale regime analysis by using bankfull discharge, multiple row bars were developed, and suspended sediment load was governed in the flow as a sand bed channel.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.7
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• pp.605-611
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• 2011

Shimmy is a self-excited vibration in lateral and torsional directions of a landing gear during either the take-off or landing. It is caused by a couple of conditions such as a low torsional stiffness of the strut, a free-play in the landing gear, a wheel imbalance, or worn parts, and it may make the aircraft unstable. This study was performed for an analysis of the shimmy stability on a small aircraft. A nose landing gear was modeled as a linear system and characterized by state-equations which were used to analyze the stability both in the frequency and time-domain for predicting whether the shimmy occurs and investigating a good design range of the important parameters. The root-locus method and the 4th Runge-Kutta method were used for each analysis. Because the present system has a simple mechanism using a friction to reinforce the stability, the friction, a non-linear factor, was linearized by a describing function and considered in the analysis and observed the result of the instability reduction.

• Journal of Korean Tunnelling and Underground Space Association
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• v.8 no.1
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• pp.13-20
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• 2006

This study proposes a new concept of a tunnel central drainage system by using a drain board to make a breakthrough on difficulties in the installation of conventional drainage system and draw-down of its drain capacity especially in long tunnels. A fundamental study has been performed for evaluation of the drain capacity of the planar drainage system adopted in this study. In fact, the system proposed makes possible to omit the side, transverse as well as central drainage pipes required in the conventional system, even if its drain capacity and any guideline for design are not available to date. In this circumstance, it is carried out to investigate the correlation between drain capacities and, shapes and posit ions of the columns of the drain board in terms of a variety of water inflows through hydrological model tests. It is shown from the tests that a drain capacity is highly influenced by the shape and the distance between the columns of a drain board in flowing direction, and a round rectangular shape of the columns leads to the highest capacity of drainage. And also, the shorter distance between the columns in flowing direction, the higher drain capacity would be achieved.