• Journal of the Korean Society of Environmental Restoration Technology
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• v.21 no.1
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• pp.83-94
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• 2018

This study presents an integrated evaluation method to assess the level of achievement of quantitative expansion goals and qualitative improvement goals based on the Aichi Biodiversity Target 11 for quantitatively expanding and qualitatively improving national protected areas. The quantitative evaluation indicators for national protected areas are the percentage of terrestrial and inland water areas protected and the percentage of marine and coastal areas protected. The quantitative evaluation indicators for national protected areas are selected as 6 indicators: 1) ecologically important areas, 2) ecological representativeness, 3) management effectiveness, 4) connectivity, 5) social equity and 6) integration. Ecologically important areas are an indicator which evaluates how many areas of particular importance for biodiversity and ecosystem services are included in national protected areas. Ecological representativeness is to assess how well national protected areas represent the ecosystem. Management effectiveness is an indicator which evaluates how effectively national protected areas are conserved and managed, and connectivity is an indicator to assess how well national protected areas are connected. Social equity is evaluating how equitably national protected areas are managed and the integration is assessing how much national protected areas are integrated into the wilder landscape and seascape. This study is significant in that it provides a perspective of qualitative improvement as well as quantitative expansion of national protected areas for biodiversity conservation through accurately understanding Aichi Biodiversity Target 11.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.2
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• pp.43-53
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• 1993

There exist two difficulties in the nonlinear wave-body problems. First is the abrupt behavior near the intersection point between the body and the free surface, and second is the far field treatment. In this paper, the far field treatment is considered. The main idea is the Taylor series expansion of free-surface geometry and the application of F.F.T. algorithm. The numerical step is as follows. The velocity potential is expressed by the Green's theorem. and the solution is obtained by iteration method. In the iteration stage, the expressions by the Green's theorem are transformed to the convolution forts with the expansion of free surface by the wave slope. Here F.F.T. is applied, so the computing time can be of O(Nlog N) where N is the number of unknowns. The numerical analysis is carried out and the results are compared with other results in linear floating body problem and nonlinear moving pressure patch problem, and good agreements are obtained. Finally nonlinear floating body radiation problem is carried out with computing time of O(Nlog N).

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.7-13
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• 2015

Generally, watermarking can be used copyright for contents such as audios, videos, images, and texts. With the development of Internet, many malicious attackers illegally copy relational databases synchronized applications Therefore, it is needed for the protection of databases copyright, because databases involve various sensitive information such as personal information, information industry, and secret national intelligence. Thus, the protection of relational databases is a major research field in the databases research topics. In this paper, we will review previous researches related the protection of relational databases and propose new method for relational data. Especially, we propose watermarking scheme for databases using reversible method in this paper. As an experimental result, the proposed scheme is very strong to malicious attacks. In addition, we proved our proposed scheme is to apply real application.

• Journal of the Korean Ceramic Society
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• v.36 no.1
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• pp.61-68
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• 1999

To analyze several defects and residual stress in sintering of layer structure materials, multiayer materials with TZP/SUS and ZT/SUS, and bilayer materials with porcelain/alumina and porcelain/Y-TZP were fabricated by sintering method. Multilayer materials prepared by pressureless sintering show the sintering defect such as warping, splitting, cracking originated from the difference of sintering shrinkage between each layer, which could be controlled by the adjustment of number and thickness in interlayer. In tape casting, a certain pressure given during sintering relaxed the sintering defects, specially warping. The residual stress in bilayer was examined with Vickers indentation method. A small tensile stress in porcelain/alumina and a large compressive stress in porcelain/Y-TZP were generated on the porcelain interface due to the thermal expansion mismatch, which affected the strength of bilayer materials. As a consequence, the sintering defects of multilayer materials and the residual stresses of bilayer materials were dominantly influenced on material design and starting material constants.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.3 no.2
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• pp.176-184
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• 1993

The glasses, which the $\beta$-spodumene as the principal crystalline phase could be precipitated, were melted by adding >, $P_2O_5, TiO_2, ZrO_2 in the Li_2O-Al_2O_3-SiO_2$ system. In order to achieve the glass-ceramic body of near-theoritical density by sintering method, the optimum condition of heat treatment, the effect of glass powder size and the properties were investigated by DTA, XRD, bulk density, thermal expansion and SEM. Addition of $P_20_5$ imProved the tendency of sintering and the sample with 9wt% $P_20_5$ content was the most dense OOdy by sintering method. The optimum condition of heat treatmemt was sintered for densitification at $740^{\circ}C$ and crystallized at $950^{\circ}C$. In the optimum condition, the relative density was above 90% and the thermal expansion was negative about $-1{\times}10^{-7}/^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.9
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• pp.795-800
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• 2008

A sublimation method using the SiC seed crystal and SiC powder as the source material is commonly adopted to grow SiC bulk single crystal. However, it has proved to be difficult to achieve the high quality crystal and the process reliability because SiC single crystal should be grown at very high temperature in closed system. The present research was focused to improve SiC crystal quality grown by PVT method through using the new inner guide tube. The new inner guide tube was designed to prevent the enlargement of polycrystalline region into single crystalline region and to enlarge the diameter of SiC single crystal. The 6H-SiC crystals were grown by conventional PVT process. The seed adhered on seed holder and the high purity SiC source materials are placed on opposite side in sealed graphite crucible surrounded by graphite insulation. The SiC bulk growth was conducted around 2300 $^{\circ}C$ of growth temperature and 50 mbar in an argon atmosphere of growth pressure. The axial thermal gradient across the SiC crystal during the growth was estimated in the range of 15${\sim}$20 $^{\circ}C$/cm.

• Journal of Sensor Science and Technology
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• v.8 no.5
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• pp.407-413
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• 1999

The resonant frequency of dielectric rod resonator can be calculated very accurately by means of the concept of electric and magnetic walls from the symmetry. But in a real situation, when the supporter is placed in the cavity, asymmetry appears due to the supporter and its dielectric constant. Then we need research into the resonance characteristic of asymmetric dielectric resonator. In this paper, for the dielectric rod resonator which is placed in the asymmetric position in the conducting cavity, the equation for resonance characteristic was derived and the resonant frequency was calculated with the eigenfunction expansion method. We found that the calculated resonant frequency is very accurate when it was compared with the experimental result and that asymmetry affects the resonant frequency more in TM mode than in TE or in hybrid mode.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.7
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• pp.604-611
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• 2004

It is well known that wall impedance essentially determines how sound wave transmits from one place to another. The wall impedance is related with its dynamic properties : for example, the mass, stiffness, and damping characteristics. It is noteworthy, however, that the wall impedance is also function of spatial characteristics of two spaces that is separated by the wall. This is often referred that the wall is not locally reacting. In this paper, we have attempted to see how the acoustic characteristics of the two spaces is affected by various structure parameters such as density, applied tension, and a normalized length of the wall. Calculations are conducted for two different modally reacting boundary conditions by modal expansion method. The variation of the Helmholtz mode and the structural-dominated mode are analyzed as the structure parameters vary. The displacement distribution of the structure, pressure and active intensity of the inside and outside cavity are presented at the Helmholtz mode and the structure-dominated mode. It is shown that the frequency characteristics are governed by both structure-and fluid-dominated mode. The results exhibit that the density of the structure is the most sensitive design parameter on the frequency characteristics for the coupling system as we could imagine in the beginning. The Helmholtz mode frequency decrease as density increases. However. it increases as applied tension and an opening size increase. The bandwidth of the Helmholtz mode is mainly affected by density of the structure and its opening size.

• Composites Research
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• v.35 no.3
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• pp.188-195
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• 2022

This paper proposes a multiscale process-structural analysis methodology and applies to a battery housing part made of the short fiber-reinforced and fabric-reinforced composite layers. In particular, uncertainties of the material properties within the microscale representative volume element (RVE) were considered. The random spatial distribution of matrix properties in the microscale RVE was realized by the Karhunen-Loeve Expansion (KLE) method. Then, effective properties of the RVE reflecting on spatially varying matrix properties were obtained by the computational homogenization and mapped to a macroscale FE (finite element) model. Morever, through the hybrid process simulation, a FE (finite element) model mapping residual stress and fiber orientation from compression molding simulation is combined with one mapping fiber orientation from the draping process simulation. The proposed method is expected to rigorously evaluate the design requirements of the battery housing part and composite materials having various material configurations.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.5
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• pp.267-275
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• 2022

Using a nonconforming mesh in enrichment methods results in several numerical issues induced by discontinuities and singularities found within the solution spaces, including the computational overhead during integration. In this study, we present a novel enrichment technique based on the selective expansion technique of moment fitting (Düster and Allix, 2020). In particular, two modifications are proposed to address the inefficiency during the integration process. First, a feedforward artificial neural network is introduced to correlate the implicit functions and integration moments. Through numerical examples, it is shown that the efficiency of the method is greatly improved when compared with existing expansion techniques, whereas the solution accuracy is maintained. Additionally, the finite element and domain representation grids are separated, which in turn improves the solution accuracy even for coarse mesh conditions.