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On-film formation of bi nanowires with extraordinary electron mobility.
Shim, Wooyoung,Ham, Jinhee,Lee, Kyoung-Il,Jeung, Won Young,Johnson, Mark,Lee, Wooyoung American Chemical Society 2009 NANO LETTERS Vol.9 No.1
<P>A novel stress-induced method to grow semimetallic Bi nanowires along with an analysis of their transport properties is presented. Single crystalline Bi nanowires were found to grow on as-sputtered films after thermal annealing at 260-270 degrees C. This was facilitated by relaxation of stress between the film and the thermally oxidized Si substrate that originated from a mismatch of the thermal expansion. The diameter-tunable Bi nanowires can be produced by controlling the mean grain size of the film, which is dependent upon the thickness of the film. Four-terminal devices based on individual Bi nanowires were found to exhibit very large transverse and longitudinal ordinary magnetoresistance, indicating high-quality, single crystalline Bi nanowires. Unusual transport properties, including a mobility value of 76900 cm(2)/(V s) and a mean free path of 1.35 mum in a 120 nm Bi nanowire, were observed at room temperature.</P>
Structure-dependent growth control in nanowire synthesis via on-film formation of nanowires
Shim, Wooyoung,Ham, Jinhee,Noh, Jin-Seo,Lee, Wooyoung Springer 2011 Nanoscale research letters Vol.6 No.1
<P>On-film formation of nanowires, termed OFF-ON, is a novel synthetic approach that produces high-quality, single-crystalline nanowires of interest. This versatile method utilizes stress-induced atomic mass flow along grain boundaries in the polycrystalline film to form nanowires. Consequently, controlling the magnitude of the stress induced in the films and the microstructure of the films is important in OFF-ON. In this study, we investigated various experimental growth parameters such as deposition rate, deposition area, and substrate structure which modulate the microstructure and the magnitude of stress in the films, and thus significantly affect the nanowire density. We found that Bi nanowire growth is favored in thermodynamically unstable films that facilitate atomic mass flow during annealing. A large film area and a large thermal expansion coefficient mismatch between the film and the substrate were found to be critical for inducing large compressive stress in a film, which promotes Bi nanowire growth. The OFF-ON method can be routinely used to grow nanowires from a variety of materials by tuning the material-dependent growth parameters.</P>
Analytical Study of the Vibration Attenuation with respect to Trackbed Systems
WooYoung Jung,SeongHyeok Lee,JinWook Lee,MinHo Kwon,BuSeog Ju 한국철도학회 2014 International Journal of Railway Vol.7 No.2
The vibration-attenuation was quantitatively compared by 3-Dimensional finite element analysis using ABAQUS, with respect to the change of the type of trackbed systems. Most common trackbed materials, including ballast and concrete were applied to the track structure, and the train-speed was set as 300km/h as Korea Train eXpress (KTX). The result of current study revealed that the ballast showed the most effective material for the vibration attenuation.
Triple-a supply chain management for automobile industry
Wooyoung Jeong,Minyoung Park,Jung Ung Min 인하대학교 정석물류통상연구원 2009 JOURNAL OF INTERNATIONAL LOGISTICS AND TRADE Vol.7 No.1
This paper presents a case study of Renault Samsung Motors (RSM) that recently encounters dynamic changes unveiling various opportunities and challenges due to increasing complexity of the supply network with growing sales volume, diversifying models, and intensifying global competition. Such competitive environment puts constant pressure on the logistics operations to reduce supply costs and lead time, but the RSM has not been paying much attention to aligning interests of supply chain partners. In 2007, RSM"s effort to build partnership with new 3PLs turned abortive due to their unexpected default on the contract throwing RSM into confusion and disruptions. In this study, the problem was investigated by examining route planning process and incentive scheme of 3PL, and an optimization model was constructed to evaluate the performance of existing 3PL operation. The results indicate that transportation cost can be reduced by relocating consolidation centers, utilizing regional terminal and redesigning routing sequence. However, the research found that the key to successful implementation of the optimized solutions is in designing effective incentive system that induces partners to participate in continuous improvement initiatives.
Wooyoung PARK,Ji-Sook HAHN 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.10
Methane has emerged a promising alternative carbon source to produce valuable chemicals. To produce lactic acid from methane, we developed lactate-tolerant methanotroph strain by adaptive evolution of Methylomonas sp. DH-1. The evolved strain survived up to 10 g/L lactate, whereas wild type could not grow even in the presence of 1 g/L of lactate. Whole genome sequencing of the evolved strain revealed a point mutation in the alaRS gene encoding alanyl tRNA synthetase. Introduction of the alaRS mutation into the wild-type strain led to an increase in lactate tolerance, suggesting this point mutation is responsible for the lactate tolerance. AlaRS catalyzes the charging of Ala to tRNAAla, but the enzyme can also mischarge Ser or Gly, which is subsequently removed by an editing activity of AlaRS. A defect in editing activity was shown to be detrimental in bacteria and humans even with very small amount of mutant proteins with Ala to Ser mutation. We identified that the identified point mutation in the catalytic domain of alaRS could reduce Ser mischarging while increasing Ala-charging activity. These results suggest that increased fidelity of alaRS activity may lead to specific changes in proteome, which in turn may increase lactate tolerance of Methylomonas sp. DH-1
Fraud Detection of FinTech by Adaptive Fraud detection algorithm
Wooyoung Moon,Soo Dong Kim 한국정보기술학회 2017 Proceedings of The International Workshop on Futur Vol.2017 No.7
With the increasing the number of FinTech services, fraud-related costs include transactions refused costs are also increasing rapidly. In Fintech domain, the fraud are analyzed through a number of fraud management systems, algorithms, and methods that have been developed and improved for card fraud detection and mobile detection. The increasing trend for real-time payments and the diversity of fast-growing services requires an improvement in the existing use of the algorithm. This paper shows an adaptive detection approach that work alongside FinTech services.