Dongyang Mirae University

Seoul, South Korea

Dongyang Mirae University

Seoul, South Korea
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Shin S.-S.,Dongyang Mirae University
Transactions of the Korean Institute of Electrical Engineers | Year: 2015

A Chebyshev filter is well known for having a sharp skirt characteristic and equi-ripple. On the other hand, a Butterworth filter has a smooth skirt characteristic and maximally flat ripple. This paper analyzes the skirt characteristics of the filters with the cascade connection. The paper deals with the Chebyshev BPF, Cascading Chebyshev BPF, Butterworth BPF, Cascading Butterworth∗ Chebyshev BPF. First of all, the paper designs the prototype analog LPF in order to analyze skirt characteristics of the BPFs. Then the paper does the frequency transformation into the BPFs and tests the BPFs with cascading them. As a result, the skirt characteristics of the Chebyshev BPF was the sharpest and those of the Cascading Chebyshev BPF, Butterworth BPF," Cascading Butterworth∗ Chebyshev BPF was superior in order. The validity of the paper was confirmed through minute measurements of test results. Copyright © The Korean Institute of Electrical Engineers.

Kim Y.J.,Sogang University | Lee J.M.,Dongyang Mirae University | Koo C.,Kyung Hee University | Nam K.,Management Information Systems
International Journal of Information Management | Year: 2013

Recent studies on IT outsourcing have examined the effect of contract specification and relationship strength on IT outsourcing performance in a separate manner. Previous studies, however, ignored the importance of the governance effectiveness that bonds contractual control and relationship strength together to deliver expected outcomes in IT outsourcing exchange. In this paper, we propose a model of IT outsourcing management where governance effectiveness mediates the effect of both contractual control and relationship strength on IT outsourcing performance. We collected data from 143 client companies of IT outsourcing and analyzed it using the PLS method. Our findings show that both contract specification and relationship strength significantly influence governance effectiveness, although contract specification carries the more effect on governance effectiveness than relationship strength does. The governance effectiveness in turn mediates the effect of contract specification and relationship strength on three sub-dimensions of outsourcing performance: cost efficiency, performance improvement, and overall satisfaction. The results and implications are further discussed. © 2013 Elsevier Ltd. All rights reserved.

Chee G.-J.,Dongyang Mirae University | Chee G.-J.,Japan Agency for Marine - Earth Science and Technology
Sensors and Actuators, B: Chemical | Year: 2016

Trichloroethylene (TCE) is one of common pollutants in soil and groundwater. TCE has a recalcitrant pollutant that is uneasy to degrade by microorganisms. A novel microbial biosensor based on Pseudomonas sp. strain ASA86 was developed for the TCE detection. A chloride ion electrode was employed as a transducer to detect the released chloride ions from TCE degraded by the bacteria, which was immobilized on a porous cellulose nitrate membrane. The performance of the biosensor was evaluated at different TCE concentrations, with different concentrations of the immobilized bacteria, pH levels, temperatures, and with different interferents. There was a linear relationship between biosensor response and TCE concentration ranging up to 4 mg/L, and the response could be detected up to 0.05 mg/L TCE concentration. The biosensor response showed good reproducibility (relative standard deviation of 6.1%) at 0.5 mg/L TCE concentration. The detection time was about 5 min under the optimum conditions of the biosensor. The optimal response was obtained at pH 8.0 and 30 °C. Compounds that have molecular structures similar to that of TCE did not significantly affect the response of the biosensor. The biosensor response remained stable over five days. This TCE biosensor shows enough sensitivity for environmental monitoring. © 2016 Elsevier B.V.

Yim K.B.,Dongyang Mirae University | Yim J.,NASA
International Journal of Precision Engineering and Manufacturing | Year: 2012

The dynamic behavior of a flexible shaft with a disk subjected to axial forces has been studied by employing the transfer matrix approach. The conventional transfer matrix was modified to include the applied axial force, and then integrated into a computer program to investigate the effect of the load force on the stability and the natural frequencies of overhung rotor systems. Two overhung rotor systems are considered. One is the cantilevered rotor and the other is the overhung rotor with an intermediate support. The gyroscopic effect of the rotor strongly influences the dynamic behavior of the shaft-disk system under axial forces not only by increasing the critical force for the stability but also by changing the instability type from divergence to flutter. © KSPE and Springer 2012.

Cho S.,Dongyang Mirae University | Lee J.Y.,Samsung
Electronic Materials Letters | Year: 2010

Thermal management issues with IC packages have been growing as electronic systems have become smaller with a higher functionality. Since the high junction temperature of IC packages induces the low performance and malfunction of electronic systems, the thermal dissipation capability of electronics is important for stable electrical performance and electro-mechanical reliability. However, the conventional cooling methods that depend on air flow path and heat sink structure is not sufficient to meet the growing thermal requirements of IC packages. Since there is limit on conventional design, such as optimization air flow path and heat sink structure, to dissipate more heat through an exhaust fan system. The main purpose of the present research is to reduce the junction temperature of the IC package by using a Printed Circuit Board (PCB) coated with new Photo-imageable Solder Resist (PSR) that has high thermal conductivity. The thermal conductivity of the newly developed PSR is about five times as high as that of the conventional PSR for PCB(0.23~0.25W/m·K). The PCB was prepared by the EIA/JEDEC standard, JESD51-7. Experimental and finite element analyses were performed to investigate the effect of SR on thermal dissipation capability. The experimental and FE results show that the high thermal conductivity of PSR can reduce the steady-status regulator surface temperature by about 3~8K as an air flow conditions around PCB. Also, the high thermal conductivity of SR is more effective under a low air heat transfer coefficient condition. Therefore, it is believed that an improved heat transfer with a PSR of high thermal conductivity should provide stable electrical performance for the IC package.

Nunoura T.,Institute of Biogeosciences | Takaki Y.,Institute of Biogeosciences | Kakuta J.,Institute of Biogeosciences | Nishi S.,Institute of Biogeosciences | And 9 more authors.
Nucleic Acids Research | Year: 2011

The domain Archaea has historically been divided into two phyla, the Crenarchaeota and Euryarchaeota. Although regarded as members of the Crenarchaeota based on small subunit rRNA phylogeny, environmental genomics and efforts for cultivation have recently revealed two novel phyla/divisions in the Archaea; the 'Thaumarchaeota' and 'Korarchaeota'. Here, we show the genome sequence of Candidatus 'Caldiarchaeum subterraneum' that represents an uncultivated crenarchaeotic group. A composite genome was reconstructed from a metagenomic library previously prepared from a microbial mat at a geothermal water stream of a sub-surface gold mine. The genome was found to be clearly distinct from those of the known phyla/divisions, Crenarchaeota (hyperthermophiles), Euryarchaeota, Thaumarchaeota and Korarchaeota. The unique traits suggest that this crenarchaeotic group can be considered as a novel archaeal phylum/division. Moreover, C. subterraneum harbors an ubiquitin-like protein modifier system consisting of Ub, E1, E2 and small Zn RING finger family protein with structural motifs specific to eukaryotic system proteins, a system clearly distinct from the prokaryote-type system recently identified in Haloferax and Mycobacterium. The presence of such a eukaryote-type system is unprecedented in prokaryotes, and indicates that a prototype of the eukaryotic protein modifier system is present in the Archaea. © 2010 The Author(s).

Chee G.-J.,Dongyang Mirae University | Chee G.-J.,Japan Agency for Marine - Earth Science and Technology
Talanta | Year: 2011

Trichloroethylene (TCE) is a toxic, recalcitrant groundwater pollutant. TCE-degrading microorganisms were isolated from various environments. The aerobic bacteria isolated from toluene- and tryptophan-containing media were Pseudomonas sp. strain ASA86 and Burkholderia sp. strain TAM17, respectively; these are necessary for inducing TCE biodegradation in a selective medium. The half-degradation time of TCE to a concentration of 1 mg/L was 18 h for strain ASA86 and 7 days for strain TAM17. While identifying toluene/TCE degradation genes, we found that in strain ASA86, the gene was the same as the todC1 gene product encoding toluene dioxygenase identified in Pseudomonas putida F1, and that in strain TAM17, the gene was similar to the tecA1 gene product encoding chlorobenzene dioxygenase identified in Burkholderia sp. PS12. A novel TCE biosensor was developed using strain ASA86 as the inducer of toluene under aerobic conditions. The TCE biosensor exhibited a linear relationship below 3 ppm TCE. Detection limit of the biosensor was 0.05 ppm TCE. The response time of the biosensor was less than 10 min. The biosensor response displayed a constant level during a 2 day period. The TCE biosensor displayed sufficient sensitivity for monitoring TCE in environmental systems. © 2011 Elsevier B.V. All rights reserved.

Lee Y.H.,Dongyang Mirae University
Journal of Ship Research | Year: 2012

Induction heating is more efficient for plate bending because of its easy operation and control of working parameters compared with heating by a torch. In this study, a more efficient method was proposed for the prediction of plate bending. The conventional analysis method using the axis symmetric coil model could not handle the varying temperature during the heating and forming process for curved plates with a convex, a concave, or a twisted curvature. The proposed method using some discrete divisions and steps in this study could overcome these difficulties and show more accurate, reasonable results of temperatures and deflections in flat or curved plates. This method is composed of multidisciplinary analyses such as an electro-magnetic analysis, a heat transfer analysis, and a deformation analysis based on inherent strain method and elastic deformation analysis.

Chee G.-J.,Dongyang Mirae University | Chee G.-J.,Japan Agency for Marine - Earth Science and Technology
Talanta | Year: 2013

Five microorganisms were used to construct a biosensor for the evaluation of low biochemical oxygen demand (BOD) in rivers. Characterization and comparison of BOD biosensors were performed using two standard solutions: glucose and glutamic acid (GGA) and artificial wastewater (AWW). Pseudomonas putida SG10 demonstrated the best response when using AWW. Trichosporon cutaneum IFO10466, however, had an extremely poor response. When evaluating the biosensor response to each component of AWW, all of the microorganisms except T. cutaneum displayed the highest response to tannic acid. In a comparison of the two standard solutions for all the microorganisms, the biosensor responses of GGA were approximately three times higher than those of AWW were. In the BOD determination of environmental samples, the biosensor BOD values evaluated using AWW were slightly lower or equivalent to BOD5 values, whereas the biosensor BOD values evaluated using GGA were considerably lower. These results suggest that GGA is suitable for the detection of high BOD in industrial wastewaters and factory effluents, while AWW is suitable for the detection of low BOD in rivers. © 2013 Elsevier B.V.

Shin M.S.,Dongyang Mirae University
Transactions of the Korean Society of Mechanical Engineers, B | Year: 2015

In this study, we present a grid refinement model in the lattice Boltzmann method (LBM) for two-dimensional incompressible fluid flow. That is, the model combines the desirable features of the lattice Boltzmann method and stream function-vorticity formulations. In order to obtain an accurate result, very fine grid (or lattice) is required near the solid boundary. Therefore, the grid refinement model is used in the lattice Boltzmann method for stream function-vorticity formulation. This approach is more efficient in that it can obtain the same accurate solution as that in single-block approach even if few lattices are used for computation. In order to validate the grid refinement approach for the stream function-vorticity formulation, the numerical simulations of lid-driven cavity flows were performed and good results were obtained. ©2015 The Korean Society of Mechanical Engineers.

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