• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.2
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• pp.127-133
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• 2013

In this paper, the study for the manufacture of the integrated composite wing is performed. The wing has a pivoting structure and high aspect ratio to increase lift drag ratio. The wing is designed with carbon fiber composite because the wing needs to be light and have sufficient strength and stiffness to satisfy structural design requirements. The number of structural members is decreased by part integration to reduce manufacturing cost and the wing is manufactured with the integrated molding process by an autoclave. The material properties are identified by the coupon tests and the structural strength and stiffness are verified through the component tests.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.6
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• pp.579-589
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• 2004

The radar signals are generally very sensitive to relative orientations between radar and target. Thus, the performance of a target recognition system significantly deteriorates as the region of aspect angles becomes broader. To address this difficulty, in this paper, we propose a method based on the multi-aspect information in order to improve the classification capability ever for a wide angular region. First, range profiles are used to extract feature vectors based on the central moments and principal component analysis(PCA). Then, a classifier with the use of multi-aspect information is applied to them, yielding an additional improvement of target recognition capability. There are two different strategies among the classifiers that can fuse the information from multi-aspect radar signals: independent methodology and dependent methodology. In this study, the performances of the two strategies are compared within the frame work of target recognition. The radar cross section(RCS) data of six aircraft models measured at compact range of Pohang University of Science and Technology are used to demonstrate and compare the performances of the two strategies.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.3
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• pp.177-184
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• 2000

The effect of the buyancy and thermocapillarity for differnent aspect ratio of flow field on melt motion and mass transfer has been numerically investigated in magnetic Czochralski crystal growth of silicon. During the process of crystal growth, the melt depth of crucible reduces so the aspect ratio of flow field also reduces. Therefore the shape of magnetic field of the flow field changes and the flow pattern also changes significantly. Together with the melt flow which forms the Marangoni convection (or thermocapillary flow) that comes from the inside the flow field, a flow circulation is observed near the corner close both to the crucible wall and the free surface. Due to this circulation, buoyancy effect has been turned out to be local rather than global. As the aspect ratio decreases, the radial component of the magnetic field prevails compared with the axial component in the flow field. Under the influence of this magnetic field, the melt flow and the temperature distribution in a meridional plane tend to depend on the radial position. As the aspect ratio decreases, the temperature gradient near the edge of the crystal decreases yielding smaller thermocapillarity, and the oxygen concentration near the crystal and the oxygen incorporation rate also decrease.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.6
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• pp.281-289
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• 2004

The temperature hump is found to be most efficient in suppressing parasitic nucleation. With the temperature humps, there are found to be observed in undersaturations along the transport path for convective-diffusive processes ranging from $D_{AB}$ = 0.0584 $\textrm{cm}^2$/s to 0.584 $\textrm{cm}^2$/s, axial positions from 0 to 7.5 cm. With decreasing Ar = 5 to 3.5, the temperature difference is increased because of the imposed nonlinear temperature profile but the rate is decreased. For 2 $\leq$ Ar $\leq$ 3.5, the rate is increased with the aspect ratio as well as the temperature difference. Such an occurrence of a critical aspect ratio is likely to be due to the effect of sidewall and much small temperature difference. The rate is decreased exponentially with the aspect ratio for 2 $\leq$ Ar $\leq$ 10. Also, the rate is exponentially decreased with partial pressure of component B, P for 1 $\leq$ P $\leq$ 100 Torr.$ B/ $\leq$ 100 Torr.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.17 no.6
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• pp.231-237
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• 2007

For an aspect ratio (transport length-to-width) of 5, Pr=3.34, Le=0.078, Pe=4.16, Cv=1.01, $P_B=50$ Torr, only thermally buoyancy-driven convection ($Gr=4.83{\times}10^5$) is considered in this study in spite of the disparity in the molecular weights of the component A ($Hg_2Cl_2$) and B which would cause thermally and/or solutally buoyancy-driven convection. The crystal growth rate and the maximum velocity vector magnitude are decreased exponentially for $3{\le}Ar{\le}5$, for (1) adiabatic walls and (2) the linear temperature profile, with a fixed source temperature. This is related to the finding that the effects of side walls tend to stabilize convection in the growth reactor. The rate for the linear temperature profiles walls is slightly greater than for the adiabatic walls far varied temperature differences and aspect ratios. With the imposed thermal profile, a fixed source region, both the rate and the maximum velocity vector magnitude increase linearly with increasing the temperature difference for $10{\le}{\Delta}T{\le}50K$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.4
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• pp.149-156
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• 2006

For an aspect ratio (transport length-to-width) of 5, Pr = 2.89, Le = 0.018, Pe = 2.29, Cv = 1.11, $P_B$=40 Torr, solutally buoyancy-driven convection $(Gr_s=3.03{\times}10^5)$ due to the disparity in the molecular weights of the component A $(Hg_2Cl_2)$ and B (He) is stronger than thermally buoyancy-driven convection $(Cr_t=1.66{\times}10^4)$. The crystal growth rate is decreased exponentially for $2.5\;{\leq}\;Ar\;{\leq}\;5$, with (1) the linear temperature profile and a fixed temperature difference, (2) the imposed thermal profile, a fixed crystal region and varied temperature difference. This is related to the finding that the effects of side walls tend to stabilize convection in the growth reactor. But, with the imposed thermal profile, a fixed source region and varied temperature difference, the rate is increased far $2\;{\leq}\;Ar\;{\leq}\;3$, and remains nearly unchanged for $3\;{\leq}\;Ar\;{\leq}\;5$.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1236-1239
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• 2002

When we see an object, we usually can say what it is easily even for the case where the object isn't shown in the frontal view. However, it is difficult to believe that all views of every object we have ever seen are fully memorized in our brain. Possibly, when an object is shown, we have some typical views of the object in our brain through our past experience and reconstruct the view to recognize what the presented object is. Non-negative Matrix Factorization (NMF) is one of the methods to extract the basis images from sample data set. The prominent feature of this method is that the reconstructed image is obtained by only additions of the basis images with suitable positive weights. So NMF can be seen more biologically plausible method than any other feature extraction methods such as Vector Quantization (VQ) and principal Component Analysis (PCA). In this paper, we adopt NMF to extract the aspect features from the set of images, which consists of various views of a given object. Some experiments are shown how much well NMF can extract the aspect features than any other methods such as VQ and PCA.

• Journal of the Korea Society of Computer and Information
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• v.21 no.3
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• pp.39-45
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• 2016

In this paper, we propose a log management service model for efficient developments of android applications. The proposed model consists of two major parts which are the log collector and the log manager service. The log collector can capture the log information of a target application without modifications, because the collector is composed by aspect-oriented programming. The collected logs are transformed to chunk of data, and the chunk of data is sent to the log management service. The log management service is an android service component and an independent application in another process. So, the log management service can reduce the workload of logging in the target application. Through a case study, we show that the proposed log management service model can reduce the log processing time compared to other models without modifications of a target application.

• Journal of the Korea Society of Computer and Information
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• v.21 no.10
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• pp.69-76
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• 2016

In this paper, we propose a real-time remote logging model for development of android applications using LBS(Location based Service). The model has two major parts: Mobile Log Management Service and Remote Log Server. Mobile Log Management Service consists of the log collector and the remote log manager. The log collector is an aspect of AOP which can collect logs from the target application without modifications of source codes. The remote log manager has a background service component so that it can receive logs whenever the log collector captures logs from the target application. Remote Log Server communicates with Mobile Log Management Service by socket interface. Therefore, Remote Log Server can show logs in real-time. To validate the efficiency of the proposed model, we show a case study, and compare the model with other models.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.896-905
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• 2006

Several soil parameters such as particle characteristics, geological element, drainage and loading conditions are influenced on the shear strength of soil. The characteristics of soil particles are important factor to the shear strength of soil. However, this component is not well considered in the determination of soil strength in Korea. The particle shape of sand was analyzed by utilizing SEM(Scanning Electron Micrograph) and compared its results in terms of aspect ratio, angularity and roughness. Based on the determined soil parameters, the ultimate bearing capacity of sandy ground was estimated by using Terzaghi bearing capacity equation.