• Transactions of Materials Processing
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• v.29 no.4
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• pp.211-217
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• 2020

This paper presents a study on the hydrogen embrittlement of Ti-6Al-4V alloys with different microstructures depending on annealing treatment. They were electrochemically charged with hydrogen and subjected to tensile tests to investigate hydrogen embrittlement behavior. Tensile test results showed that the elongation of Ti-6Al-4V alloy specimens was remarkably decreased with increasing the volume fraction of β phase after hydrogen charging. This is because the β phase with a relatively low diffusivity tends to easily form a hydride at grain boundaries during electrochemical hydrogen charging. After hydrogen charging of the Ti-6Al-4V alloy specimen, it found that silver particles were decorated mostly at the grain boundary, and coarser silver particles were usually formed in the specimen annealed at 950 ℃. Therefore, the specimen having higher β phase fraction shows a poor hydrogen embrittlement resistance because the β phase promotes the formation of coarse hydride during electrochemical hydrogen charging, which leads to a large decrease in ductility.

• Korean Journal of Materials Research
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• v.18 no.4
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• pp.211-217
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• 2008

A $ZrO_2$ coating solution containing $ZrO_2$ photo-catalysis, which is transparent in visible light, was prepared by the hydrolysis of alkoxide, and thin films on the $SiO_2$ glass substrate were formed in a dipcoating method. These thin films were heat-treated at temperatures ranging from $250^{\circ}C-800^{\circ}C$ and their characteristics were subjected to thermal analysis, XRD, spectrometry, SEM, EDS, contact angle measurement, and AFM. Tetragonal $ZrO_2$ phase was found in the thin film heat treated at $450^{\circ}C$, and anatase $TiO_2$ phase was detected in the thin film heat-treated at $600^{\circ}C$ and above. The thickness of the films was approximately 300 nm, and the roughness was 0.66 nm. Thus, the film properties are excellent. The films are super hydrophilic with a contact angle of $4.0^{\circ}$; moreover, they have self-cleaning effect due to the photo catalytic property of anatase $TiO_2$.

• Environmental Engineering Research
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• v.17 no.4
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• pp.211-216
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• 2012

Quantification of the airborne microorganisms (bacteria and fungi) at a swine wastewater treatment plant was performed. Microbial samples were collected at three different phases of the treatment process over a 1-yr period. Cultivation methods based on the viable counts of mesophilic heterotrophic bacteria and fungi were performed. The concentrations of airborne bacteria ranged up to about $5{\times}10^3$ colony-forming unit (CFU)/$m^3$, and those of airborne fungi ranged up to about $9{\times}10^2CFU/m^3$. The primary treatment (e.g., screen, grit removal, and primary sedimentation) was found to be the major source of airborne microorganisms at the site studied, and higher levels of airborne bacteria and fungi were observed in summer. High levels of the respirable bioaerosol (0.65 to $4.7{\mu}m$ in size) were detected in the aeration phase. Among the environmental factors studied, temperature was strongly associated with fungal aerosol generation (with a Spearman correlation coefficient of 0.90 and p-value <0.01). Occupational biorisks are discussed based on the observed field data.

• Structural Engineering and Mechanics
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• v.18 no.2
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• pp.211-229
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• 2004

The main purpose of this paper is the numerical analysis of the non-linear seismic response of a RC building mock-up. The mock-up is subjected to different synthetic horizontal seismic excitations. The numerical approach is based on a 3D-model involving multilayered shell elements. These elements are composed of several single-layer membranes with various eccentricities. Bending effects are included through these eccentricities. Basic equations are first written for a single membrane element with its own eccentricity and then generalised to the multilayered shell element by superposition. The multilayered shell is considered as a classical shell element : all information about non-linear constitutive relations are investigated at the local scale of each layer, whereas balance and kinematics are checked afterwards at global scale. The non-linear dynamic response of the building is computed with Newmark algorithm. The numerical dynamic results (blind simulations) are considered in the linear and non linear cases and compared with experimental results from shaking table tests. Multilayered shell elements are found to be a promising tool for predictive computations of RC structures behaviour under 3D seismic loadings. This study was part of the CAMUS International Benchmark.

• Journal of Integrative Natural Science
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• v.5 no.4
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• pp.211-215
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• 2012

Single-crystalline silicon nanowire arrays (SiNWAs) using electroless metal-assisted etchings of p-type silicon were successfully fabricated. Ag nanoparticle deposition on silicon wafers in HF solution acted as a localized micro-electrochemical redox reaction process in which both anodic and cathodic process took place simultaneously at the silicon surface to give SiNWAs. The growth effect of SiNWs was investigated by changing of etching times. The morphologies of SiNWAs were obtained by SEM observation. Well-aligned nanowire arrays perpendicular to the surface of the silicon substrate were produced. Optical characteristics of SiNWs were measured by FT-IR spectroscopy and indicated that the surface of SiNWs are terminated with hydrogen. The thicknesses and lengths of SiNWs are typically 150-250 nm and 2 to 5 microns, respectively.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.3
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• pp.211-216
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• 2013

A wind generator system model includes wind model, rotor dynamics, synchronous generator, power converter, distribution line and infinite bus. This paper investigates the low-Voltage Ride-Through capability of PMSG wind turbine in a variable speed. The drive train of a wind turbine on 2-mass modeling can observe the shaft torsional vibration when the low-voltage occur. To reduce the torsional vibration when the low-voltage occur, this paper designs suppression control algorithm of the torsional vibration and implements simulation. The simulation based on MATLAB/SIMULINK has validated at the transient state of the PMSG and an experiment using 3kW simulator has validated the LVRT control.

• Journal of the Earthquake Engineering Society of Korea
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• v.22 no.3
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• pp.211-217
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• 2018

The Pohang earthquake with a magnitude of 5.4 occurred on November 15, 2018. The epicenter of this earthquake located in south-east region of the Korean peninsula. Since instrumental recording for earthquake ground motions started in Korea, this earthquake caused the largest economic and life losses among past earthquakes. Korea is located in low-to moderate seismic region, so that strong motion records are very limited. Therefore, ground motions recorded during the Pohang earthquake could have valuable geological and seismological information, which are important inputs for seismic design. In this study, ground motions associated by the 2018 Pohang earthquake are generated using the point source model considering domestic geological parameters (magnitude, hypocentral distance, distance-frequency dependent decay parameter, stress drop) and site amplification calculated from ground motion data at each stations. A contour map for peak ground acceleration is constructed for ground motions generated by the Pohang earthquake using the proposed model.

• Genomics & Informatics
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• v.14 no.4
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• pp.211-215
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• 2016

The alteration of alternative splicing patterns has an effect on the quantification of functional proteins, leading to phenotype variation. The splicing quantitative trait locus (sQTL) is one of the main genetic elements affecting splicing patterns. Here, we report the results of genome-wide sQTLs across 141 strains of Arabidopsis thaliana with publicly available next generation sequencing datasets. As a result, we found 1,694 candidate sQTLs in Arabidopsis thaliana at a false discovery rate of 0.01. Furthermore, among the candidate sQTLs, we found 25 sQTLs that overlapped with the list of previously examined trait-associated single nucleotide polymorphisms (SNPs). In summary, this sQTL analysis provides new insight into genetic elements affecting alternative splicing patterns in Arabidopsis thaliana and the mechanism of previously reported trait-associated SNPs.

• Journal of Ecology and Environment
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• v.36 no.4
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• pp.211-216
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• 2013

The purpose of this study is to examine distribution and abundance of wintering raptors in Korea during 2000-2007 which is a rare data set for covering large landscape areas. Total 6,643 raptors of 16 species were recorded at 94 different points in west, south and east coasts, and rivers of inland areas all over Korea. During the study period, the most abundant raptors were black vulture (Aegypius monachus, 62.3%), common kestrel (Falco tinnunculus, 11.0%) and common buzzard (Buteo buteo, 10.0%), and these 3 birds were dominant species in inland areas and also considered as resident species except for black vulture. Also, there was a difference among 5 different habitat types. Black vultures were most found in estuaries whereas common buzzard and common kestrel could be found in coastal areas. Presumably raptors prefer reservoirs and estuaries probably due to lower human disturbance in these areas, and management efforts should be concentrated in inland areas for black vulture and coastal areas for common kestrel and common buzzard.

• Journal of Computing Science and Engineering
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• v.7 no.4
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• pp.211-219
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• 2013

Human-centered computing (HCC) as a field was defined several years ago. Since then, the Web has grown significantly, and so has its impact in society at every level, creating the grounds for a new Web science. In this paper, we examine the definitions of HCC and Web science, and discuss how they might be related. On the one hand, HCC can be viewed as a set of methodologies, and on the other hand, Web science can be viewed as a platform or repository, from which behavioral data can be drawn. We examine the relationship between the two, and summarize three different research approaches that in many ways show this intersection.