• Journal of Ocean Engineering and Technology
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• v.13 no.3 s.33
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• pp.92-99
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• 1999

High temperature and pressure materials in power plant are degraded by creep damage, if they are exposed to constant loads for long times, which occurs in load bearing structures of pressurized components operationg at elevated temperatures. Many conventional measurement techniques such as replica method, electric resistance method, and hardness test method for measuring creep damgage have been used. So far, the replica method is mainly used for the inspection of high temperature and pressure components. This technique is, however, restricted to applications at the surface of the testpieces and cannot be used to material inside. In this paper, ultrasonic evaluation for the detection of creep damage in the form of cavaties on grain boundaries or intergranular microcracks were carried out. And the absolute measuring method of quantitative ultrasonic velocity technique for Cr-Mo material degradation was analyzed. As a result of ultrasonic tests for crept for specimens, we founded that the sound velocity was decreased as increase of creep life fraction(${phi}c$) and also, confirmed that hardness was decreased as increase of creep life fraction(${phi}c$).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.12
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• pp.982-987
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• 2011

In this study, $Ge_8Se_{(2+x)}Te_{(6-x)}$ thin film amorphous-to-crystalline phase-change rate was evaluated in using a nano-pulse scanner. The focused laser beam with a diameter <10 ${\mu}m$ was illuminated in the power (P) and pulse duration (t) ranges of 1-31 mW and 10-460 ns, respectively, with subsequent detection of the responsive signals reflected from the film surface. We also evaluated the material characteristics, such as optical absorption and energy gap, crystalline phases, and sheet resistance of as-deposited and annealed films. The result of experiments showed that the thermal stability of the Ge-Se-Te film is largely improved by adding Se.

• Structural Engineering and Mechanics
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• v.60 no.3
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• pp.405-412
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• 2016

Bone is a living material with a complex hierarchical structure that gives it remarkable mechanical properties. Bone constantly undergoes mechanical. Its quality and resistance to fracture is constantly changing over time through the process of bone remodeling. Numerical modeling allows the study of the bone mechanical behavior and the prediction of different trauma caused by accidents without expose humans to real tests. The aim of this work is the modeling of the femur fracture under static solicitation to create a numerical model to simulate this element fracture. This modeling will contribute to improve the design of the indoor environment to be better safe for the passengers' transportation means. Results show that vertical loading leads to the femur neck fracture and horizontal loading leads to the fracture of the femur diaphysis. The isotropic consideration of the bone leads to bone fracture by crack propagation but the orthotropic consideration leads to the fragmentation of the bone.

• Korean Journal of Veterinary Service
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• v.30 no.4
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• pp.505-510
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• 2007

This study was conducted to detect ${\beta}$-lactam antibiotic-resistant genes in the 400 E coli isolates from porcine fecal samples in Korea by a DNA chip. The DNA chip contains the specific probe DNAs of the ${\beta}$-lactam antibiotic-resistant genes that had been labeled with a mixture of primer set designed to amplify specific genes (PSE, OXA, FOX, MEN, CMY, TEM, SHV, OXY and AmpC) using a multiplex polymerase chain reaction (PCR). Of 400 isolates 339 contained at least one ${\beta}$-lactamases gene. Resistance to ${\beta}$-lactamases was mediated mainly by AmpC (n = 339, 100%), and followed by TEM (n = 200, 59.0%), CMY (n = 101, 29.8%), PSE (n = 30, 8.9%) and both OXA and SHV genes (n = 20, 5.9%), while the FOX, MEN and OXY genes were not detected. The other sixty-one did not contain any ${\beta}$-lactamase genes even though they were resistant to antimicrobial drugs. In conclusion, the DNA chip system can be used as a rapid and reliable method for detecting of ${\beta}$-lactamases genes, which will help veterinarians select the antibiotics for monitoring and treating of animal diseases.

• Journal of Sensor Science and Technology
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• v.29 no.2
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• pp.112-117
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• 2020

Xylene is a hazardous volatile organic compound that should be precisely measured to monitor indoor air quality. However, the selective and sensitive detection of ppm-level xylene using oxide-semiconductor gas sensors remains a challenge. In this study, pure and Cr-doped Co₃O₄ nanoparticles (NPs) were prepared using flame spray pyrolysis, and their gas-sensing characteristics to 5-ppm xylene at 250 ℃ were investigated. The 4 at% Cr-doped Co₃O₄ NPs exhibited a high gas response to 5-ppm xylene (resistance ratio to gas and air = 39.1) and negligible cross-responses to other representative and ubiquitous indoor pollutants such as ethanol, benzene, formaldehyde, carbon monoxide, and ammonia. In this paper, the enhancement of the gas response and selectivity of Co₃O₄ NPs to xylene by Cr doping was discussed in relation to the catalytic promotion of the gas-sensing reaction. This sensor can be used to monitor indoor xylene.

• The Plant Pathology Journal
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• v.30 no.4
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• pp.407-415
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• 2014

Viral diseases have been a major limiting factor threating sustainable potato (Solanum tuberosum L.) production in Pakistan. Surveys were conducted to serologically quantify the incidence of RNA viruses infecting potato; Potato virus X (PVX), Potato virus Y (PVY), Potato virus S (PVS), Potato virus A (PVA), Potato virus M (PVM) and Potato leaf roll virus (PLRV) in two major potato cultivars (Desiree and Cardinal). The results suggest the prevalence of multiple viruses in all surveyed areas with PVY, PVS and PVX dominantly widespread with infection levels of up to 50% in some regions. Co-infections were detected with the highest incidence (15.5%) for PVX and PVS. Additionally the data showed a positive correlation between co-infecting viruses with significant increase in absorbance value (virus titre) for at least one of the virus in an infected plant and suggested a synergistic interaction. To test this hypothesis, glasshouse grown potato plants were challenged with multiple viruses and analyzed for systemic infections and symptomology studies. The results obtained conclude that multiple viral infections dramatically increase disease epidemics as compared to single infection and an effective resistance strategy in targeting multiple RNA viruses is required to save potato crop.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.585-587
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• 1999

The rotorbody and rotor winding of generator are isolated by an insulator and the output characteristic of the generator is maintained in the best states. Only when an insulation resistance between them is over a certain extent. The aim of this research is to develop the simulator for rotor earth fault detection circuits. It is composed of the power resource which is to control the virtual field voltage, stepping motor which is to give virtual ground. It is possible to inspect with the device and program developed in this study in the same as real operating condition and evaluate the integrity of generator rotor through the function of data acquisition and graphic output. If these technologies will be applied to the inspection, prevent a damage of the generator and contribute to improve maintenance reliance.

• 한국가스학회:학술대회논문집
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• 2001.10a
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• pp.58-68
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• 2001

Microbiologically influenced corrosion (MIC) of carbon steel gas pipeline in soil environments was investigated at field and laboratory MIC is very severe corrosion and it is not easy to distinguish this corrosion from Inorganic corrosion because of its localized, pitting-type character Therefore, it is important to provide proper assessment techniques for the prediction, detection, monitoring and mitigation of MIC. It is possible to predict the MIC risk, i.e., the activity of sulfate-reducing bacteria (SRB) through the analysis of soil environments. Chemical, microbiological and surface analysis of corrosion products and metal attacked could reveal the possibility of the occurrence of MIC. Various electrochemical and surface analysis techniques could be used for the study of MIC. Among these techniques, thin-film electrical resistance (ER) type sensors are promising to obtain localized corrosion rate of MIC induced by SRB. It is also important to study the effect of cathodic protection (CP) on the MIC In case of coated pipeline, the relationship between coating disbondment and the activity of SRB beneath the disbanded coating is also important.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.4
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• pp.285-292
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• 2017

Antibiotics have been used for treating human and animal disease and enhancing growth of cattle, swine, and poultries. However, overused antibiotics can be released into the environment and produce antibiotic resistance genes (ARGs) in the environment. Main objective of this research was to monitor residual of antibiotics in solid matrix such as manure, wastewater sludge, soil and sediment. Total of six antibiotics, Chlortetracycline (CTC), Oxytetracycline (OTC), Tetracycline (TC), Sulfamethazine (SMT), Sulfamethoxazole (SMX), Sulfathiazole (STZ), used for both human and animal was monitored. Result showed that the detection frequency of 6 antibiotics was ordered SMT (100%) > TC = CTC (75%) > OTC (38%) > STZ (13%) > SMZ (0%) and the highest concentration ($309.83{\mu}g\;kg^{-1}$, SMT) was observed in manure. Comparing residual concentration of antibiotics (TC, CTC, and OTC) in soil and sediment, higher concentration was observed in sediment indicating that dissolved forms of antibiotics are released into river and sorbed into sediment particle. In conclusion, monitoring for residual of antibiotics in the environment is necessary and more research should be conducted to verify the source of antibiotic release.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.2
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• pp.153-162
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• 2014

We show that carbon nanotube sensors with gold particles on the single-walled carbon nanotube (SWNT) network operate as Schottky barrier transistors, in which transistor action occurs primarily by varying the resistance of Au-SWNT junction rather than the channel conductance modulation. Transistor characteristics are calculated for the statistically simplified geometries, and the sensing mechanisms are analyzed by comparing the simulation results of the MOSFET model and Schottky junction model with the experimental data. We demonstrated that the semiconductor MOSFET effect cannot explain the experimental phenomena such as the very low limit of detection (LOD) and the logarithmic dependence of sensitivity to the DNA concentration. By building an asymmetric concentric-electrode model which consists of serially-connected segments of CNTFETs and Schottky diodes, we found that for a proper explanation of the experimental data, the work function shifts should be ~ 0.1 eV for 100 pM DNA concentration and ~ 0.4 eV for $100{\mu}M$.