• Journal of the Korean Institute of Telematics and Electronics B
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• v.29B no.1
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• pp.94-101
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• 1992

The multilayer perceptron, trained by the error back-propagation learning rule, has been known as a mapping network which can represent arbitrary functions. However depending on the complexity of a function and the initial weights of the multilayer perceptron, the error back-propagation learning may fall into a local minimum or a flat area which may require a long learning time or lead to unsuccessful learning. To solve such difficulties in training the multilayer perceptron by standard error back-propagation learning rule, the paper proposes a learning method which progressively enlarges the learning domain from a small area to the entire region. The proposed method is devised from the investigation on the roles of hidden nodes and connection weights in the multilayer perceptron which approximates a function of one variable. The validity of the proposed method was illustrated through simulations for a function of one variable and a function of two variable with many extremal points.

• Journal of The Korean Astronomical Society
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• v.28 no.2
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• pp.119-137
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• 1995

The $UBVI_{KC}$ CCD photometry was performed in the central region(${\sim}20'{\times}20'$) of the extremely young open cluster IC1805. Member stars were selected in the (B-V)-(U-B) and (V-I)-(B-V) color-color planes. Applying recent stellar evolutionary models, we derived the age, age-spread, and initial mass function(IMF) of the cluster. IC1805 was found to be an extremely young($t_{age}{\sim}1.5Myr$) and has a flat IMF with the slope of ${\Gamma}=-1.0{\pm}0.2$.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.8
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• pp.891-897
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• 1992

A local iterative Image restoration method Is Introduced that processes with varying iteration numbers according to the local statistics. In general almost of the Iterative method applies Its algorithm to the whole Image without considering the local pixel informations, which Is not so effective for the processing time. Usually the edges or details have an Important role In visual effect. So in this paper we process the edges or the details many times while In the flat region we just pass over or decrease iterations. This method shows good MSE (Mean Square Error) improvement, better subjective qualify and reduced processing time.

• International Journal of Automotive Technology
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• v.6 no.5
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• pp.513-517
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• 2005

A full-bead of multi-layer-steel engine head gasket, taking charge of the dynamic sealing of combustion chamber, is susceptible to fatigue failure. The fatigue durability of full-bead was assessed with the finite element analysis results and the high-cycle multi-axial fatigue theory. The assessment aimed to reveal the effects of the forming parameters and dimensions of full-bead. The results show that the selection of embossing parameters producing less deformation of bead plate is beneficial for the improvement of durability while the flatting has marginal influence. The fatigue durability also improves with the increase in the width of full-bead and the radial length of bore-side flat region. However, the dimensional effects are limited due to the occurrence of snap-through.

• Journal of the Optical Society of Korea
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• v.9 no.4
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• pp.140-144
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• 2005

In this paper we have investigated the guiding properties of photonic crystal fibers (PCFs) with a square-lattice of air-holes in the cladding. We have shown numerical results of PCFs with various air hole sizes and hole-to-hole spacings over a wide wavelength range. The group velocity dispersion, effective area and effective refractive index of PCF have been calculated numerically. The waveguide dispersion has greatly affected the group velocity dispersion when hole-to-hole spacing is about $1{\mu}m$. The effective area is quite flat over the wide spectral range whether the hole-to-hole spacing is large or ratio of diameter to pitch is large. From the field distribution, we found that the field is tightly confined within the core region of PCF when the pitch is $3{\mu}m$ and the air-filling fraction is 0.9.

• Animal Systematics, Evolution and Diversity
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• v.25 no.3
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• pp.287-289
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• 2009

The leucosiid crabs are common species on soft sediment from the intertidal flat to shelf and slope depths. The genus Nursia Leach, 1817 is characterized by the pentagonal shape of the carapace and the presence of the buccal cavern on the pterygostomian region. As a result of the systematic study on the Korean brachyuran species, Nursia rhomboidalis (Miers, 1879) is newly recorded in Korean fauna. Korean Leucosiidae is now composed of 14 species belonging to eight genera. The description and illustrations of this species are provided.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.445-450
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• 1997

Optimal design of a piezoelectric smart structure is studied for cabin noise control. A cubic shaped acoustic cavity with a flat plate which covers one side is taken as the problem. The sensor signal is returned to the actuator through a negative gain. The acoustic cavity is modeled using the modal approach which represents the pressure fields in the cavity as a sum of mode shapes of the cavity with unknown coefficients. By using orthogonality of the mode shapes of the cavity, finite element equation for the structure with the influence of the acoustic cavity is derived. The objective function is the average pressure at a certain region, so-called silent zone, in the cavity and the design variables are the locations and sizes of the piezoelectric actuator and sensor. The optimal design is performed at several frequencies and the results show a remarkable noise reduction.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.7
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• pp.672-676
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• 2010

In a railway vehicle, corrugated steel panel is widely used for the floor structure because of its high bending stiffness and light weight. However, this panel shows lower sound insulation performance than that of the flat plate with the same weight. Especially, in a particular frequency region, transmission loss(TL) rapidly decreases and it results in the deterioration of sound insulation performance of the overall floor structure. This study identifies that the severe decrease in TL is caused from the local resonance of the periodic corrugated structure. TL decrease by local resonance is investigated by experiment and finite element analysis. Finally, design modification of the corrugation is proposed to improve TL and the effect is verified by experiment.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.163-171
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• 2003

Most of existing beam-to-column connections are reinforced symmetrically because of reverse action cause by earthquake but in the weak-earthquake region like Korea connections reinforced asymmetrically can be used. Specially, the connections between CFT(Concrete Filled Tube) column and H-shape beam can be applied by simplified lower diaphragm. The tensile capacity of Combined Cross Diaphragm for upper reinforcing was tested by simple tension test and four types for lower reinforcing; Combined Cross, None, Horizontal T-bar and Vertical Plate were tested by ANSI/AISC SSPEC 2002 loading program. Horizontal T-bar and stud bolts in vertical flat bar transmit tensile stress from bottom flange of beam to filled concrete. All test specimens were satisfied 0.01 radian of inelastic rotational requirement in ordinary moment frame of AISC seismic provision. As the results of parametric studies, simplified lower diaphragms demonstrated an outstanding strength, stiffness and plastic deformation capacity to use sufficient seismic performance in the field.

• Journal of The Korean Astronomical Society
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• v.52 no.2
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• pp.49-55
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• 2019

The New Vacuum Solar Telescope (NVST) is the largest solar telescope in China. When using CCDs for imaging, equal-thickness fringes caused by thin-film interference can occur. Such fringes reduce the quality of NVST data but cannot be removed using standard flat fielding. In this paper, a correction method based on multi-scale decomposition and adaptive partitioning is proposed. The original image is decomposed into several sub-scales by multi-scale decomposition. The region containing fringes is found and divided by an adaptive partitioning method. The interference fringes are then filtered by a frequency-domain Gaussian filter on every partitioned image. Our analysis shows that this method can effectively remove the interference fringes from a solar image while preserving useful information.