• Journal of Ecology and Environment
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• v.38 no.3
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• pp.343-352
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• 2015

The landscape setting of a habitat strongly influences the distribution, abundance, and species composition of waterfowl. Thus, habitat assessment is very important to understand the habitat characteristics that sustain waterfowl assemblages. In this study, we hypothesized that the excessive use of artificial materials when new wetlands are constructed negatively influences wintering waterfowl. To test this hypothesis, we measured environmental factors, assessed habitat, and investigated waterfowl at 13 artificial wetlands in the Nakdong River Basin. There were greater numbers of waterfowl species and individuals in artificial wetlands with high habitat assessment scores. In contrast, environmental factors did not affect waterfowl distribution. In particular, features of natural habitats, such as macrophytes and sandbars, and the surrounding land-use patterns were important factors for sustaining waterfowl assemblages in each created wetland. Our results show that promoting naturalness in wetlands and surrounding areas would increase the species diversity and abundance of waterfowl. Further, complex habitats, such as wetlands and some terrestrial habitats, support both aquatic and terrestrial species because mixed habitats feature a larger array of food sources than more limited habitats do.

• Progress in Superconductivity and Cryogenics
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• v.20 no.1
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• pp.1-10
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• 2018

The improvement of critical current properties of $REBa_2Cu_3O_{7-x}$ (REBCO) coated conductors by introducing artificial pinning centers (APCs) is examined with respect to the field-angle anisotropy, high-field performance and relaxation property with time. Nano-rods along the c-axis introduced by PLD method and isotropic nano-particles introduced by TFA-MOD method are treated. The theoretical analysis is also shown to understand the effect of APCs quantitatively. The effects of superconducting layer thickness that influences the high-field performance and relaxation property are also discussed. It is shown that the upper critical field, which is another important factor to determine the high-field property, can be improved by introduction of APCs through electron scattering at interfaces with the superconducting matrix. The optimum critical current property can be obtained by properly designing the morphology and number density of APCs and the superconducting layer thickness.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.7
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• pp.36-43
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• 2003

In this paper, the warm forging process sequence has been determined to manufacture the warm forged product for the precision bevel gear used as the differential gear unit of a commercial automobile. The preform shape of bevel gear influences the dimensional accuracy and stiffness of final product. So, the design parameters related preform shape such as aspect ratio and chamfer length having an influence the formability of forged product are analyzed. Then the optimal conditions of design parameters have been selected by artificial neural network (ANN). Finally, to verify the optimal preform shape, the experiments of the warm forging of the bevel gear have been executed. The proposed method can give more systematic and economically feasible means for designing preform shape in metal forming process.

• Structural Engineering and Mechanics
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• v.51 no.2
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• pp.299-313
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• 2014

In the first part of this paper, the influences of some of crack parameters on natural frequencies of a cracked cantilever Functionally Graded Beam (FGB) are studied. A cantilever beam is modeled using Finite Element Method (FEM) and its natural frequencies are obtained for different conditions of cracks. Then effect of variation of depth and location of cracks on natural frequencies of FGB with single and multiple cracks are investigated. In the second part, two Multi-Layer Feed Forward (MLFF) Artificial Neural Networks (ANNs) are designed for prediction of FGB's Cracks' location and depth. Particle Swarm Optimization (PSO) and Back-Error Propagation (BEP) algorithms are applied for training ANNs. The accuracy of two training methods' results are investigated.

• KSTLE International Journal
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• v.10 no.1_2
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• pp.43-47
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• 2009

Influences of carbonaceous ingredient as a solid lubricant in automotive friction materials on friction properties were studied. Three types of carbonaceous ingredients such as natural graphite, artificial graphite, and cokes were mixed using a constrained mixture design. A 1/5 scale brake dynamometer was used to obtain tribological properties. Results showed that cokes substantially increased the friction coefficient, and natural graphite effectively reduced stick-slip phenomena. This significant difference was attributed to the formation of the friction film on the brake pad which was shown to be strongly dependent on the graphite types. The different crystal structures of the carbonaceous solid lubricants played a significant role in the formation of friction film at the interface.

• Explosives and Blasting
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• v.36 no.3
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• pp.1-9
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• 2018

This study was conducted to evaluate the influences of the angle of artificial joints, the distance between the artificial joints and the blast hole, and the number of artificial joints on the pressure wave propagation, crack propagation, and blast wave velocity. The evaluation was conducted numerically by use of the Euler-Lagrange solver supported by the AUTODYN, which is a dynamic FEM program. As a result, it was found that the blast wave velocity was decreased most rapidly as either the distance between the artificial joint and the blast hole was decreased or the angle of the artificial joint was increased. In contrast to the case of no artificial joint, the amount of attenuation of the blast wave velocity was considerably large when an artificial joint was present. However, the effect of the number of artificial joint on the attenuation of the blast wave velocity was negligible under the given condition.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.1
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• pp.168-176
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• 2010

Stability and durability of the artificial reefs (ARs) for wildstock enhancement have been a key issue. We surveyed the side scan sonar (SSS), multi beam echo sounder (MBES) and scuba diving surveys confirmed that the ARs stability was age and type-dependent. A case of the stability of 8,438 ARs (60 group ARs) installed at 4 sites (Yangyang, Gangeung, Donghae and Samcheok) along the Gangwon coast of the East Sea (Sea of Japan). And a confirmation amount to 85.4% ARs remained safe, the rest 14.6% being influenced by a physical parameter of the waters. The representative influences by their circumstances were of breakage (6.3%). capsizing (8.3%). A group of a ARs to 61.7% ARs remained safe, the rest 38.3% being influenced by a physical parameter of the waters. The representative influences by their circumstances were of buried.

• Resources Recycling
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• v.16 no.1 s.75
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• pp.68-72
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• 2007

The influences of reduction time, potential difference and ionic concentration flow rate have been investigated on the electrolytic recovery of silver from artificial photographic wastewater in continuous flow reactor system. As the initial concentration of silver ion and applied potential were increased, the amount of silver recovered was observed to be raised. Also, the electrolytically recovered material from artificial wastewater was proved to be pure silver based on the qualitative analyses by EPMA and XRD.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.12
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• pp.565-572
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• 2017

Traditional method for time series analysis, autoregressive integrated moving average (ARIMA) allows to mine significant patterns from the past observations using autocorrelation and to forecast future sequences. However, Korean baseball games do not have regular intervals to analyze relationship among the past attendance observations. To address this issue, we propose artificial neural network (ANN) based attendance prediction model using various measures including performance, team characteristics and social influences. We optimized ANNs using grid search to construct optimal model for regression problem. The evaluation shows that the optimal and ensemble model outperform the baseline model, linear regression model.

• Korean Institute of Interior Design Journal
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• no.19
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• pp.45-52
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• 1999

This study is on Buckminster Fuller, who is generally known as a structure engineering architect, and his influences. Fuller's radical and utopian ideas and designs were regarded as 'paper architecture'. But considering today's high cost of energy and the limited natural resources, Fuller's Dymaxion theory must be re-evaluated. Fuller's influences on the contemporary architecture are summarized as follows. 1) His idea of controlling the environment through the use of technology influenced today's 'High-Tech' architects. Architecture is no-longer designed purely by its formal character, but becomes a tool of investigating environmental significance of modern technology. 2) Through systemizing mechanical equipment, Dymaxion House prototype, and aggregation of high-tech mechanical equipments, influenced Archigram & Metabolist's capsule idea. It is expressed as a plug-in module equipment of 'High-Tech' architecture which has flexible interior with mechanical exterior image. 3) Megastructure. The Manhattan dome project gave an influence to many engineer/architects who tried to achieve an ideal artificial environment. This is in connection to 1960's utopian projects. Today's megastructures show new possibilities in urbanism and architecture. Fuller's comprehensive idea of humans living in harmony in the universe shows possibilities not only in structural engineering, but in solving various problems that confront today's architecture.