• Journal of Korea Water Resources Association
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• v.43 no.8
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• pp.747-755
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• 2010

Distributed Models have relative weak points due to the amount of computer memory and calculation time required for calculating water flow using a numerical analysis based on kinematic wave theory when compared to the conceptual models used so far. Typically, the distributed models have been mainly applied to small basins. It was necessary to decrease the resolution of the grid to make it applicable for large scale watersheds, and because it would take up too much time to calculate using a higher resolution. That has been one of the more difficult factors in applying the model for actual work. In this paper, MPI (Message Passing Interface) technique was applied to solve the problem of calculation time as it is one of the demerits of the distributed model for performing physical and complicated numerical calculations for large scale watersheds. The comparison studies were performed a single domain and a divided small domain in Yongdam Dam watershed in case of typoon 'Ewiniar' at 2006. They were compared to analyze the application effects of parallelization technique. As a result, a maximum of 10 times the amount of calculation time was saved but keeping the level of quality for discharge by using parallelization code rather than a single processor.

• Journal of Korean Society of Transportation
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• v.22 no.6
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• pp.77-88
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• 2004

This study aims at developing the model that is able to detect the compression wave, which is included as a similar situation in incidents, that causes false applicable to the similar character such as incidents in the incident detection model for expressways. In this study, it has been checked whether the number of false alarms is decreased or not by modularizing this model for being able to applicable to other models such as DES and DELOS, etc. which do not perform the compression wave test based on the compression wave test process of APID model which has been being used in the expressway traffic management system currently. The evaluation in this study focuses on the sensitivity of the model and the results analysis is performed classified by each polling cycle. And how well these models are working is evaluated by each polling cycle. In addition to this, the detection rate, the false alarm rate and the average detection time in both the existing models and the model in this study are calcuated. As a result of appling the model in this study, it is found that the false alarm rate is improved through the reasonable decrease in the number of false alarm frequencies and there are not remarkable changes concerning the detection rate and the average detection time. To sum up, it is expected that a good number of improvement effects will be occurred when this model is applied to the actual expressway traffic management system.

• Journal of Life Science
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• v.23 no.2
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• pp.311-318
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• 2013

Schisandra chinensis containing a variety of pharmacologically active lignans has been traditionally used in oriental medicine. In this study, anti-inflammatory compounds were screened from the hexane extracts of S. chinensis by activity-guided fractionation. First, we investigated the regulatory effects on the expression of E-selectin, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) with 38 fractions from the hexane extracts of S. chinensis in human umbilical vein endothelial cells (HUVECs). As a result, SCKH1 among the 38 fractions from the hexane extract of S. chinensis was selected for further analysis based on its unique regulatory effect on cell adhesion molecules, especially on VCAM-1, in LPS-stimulated HUVECs. The subsequent activity-guided fractionation of SCKH1 resulted in the purification of SCKH1PAIBPB, which was found to suppress the expression of VCAM-1, MCP-1, IL-6 and IL-8 in HUVECs stimulated with LPS, and to inhibit the adhesive capacity between HUVECs and monocytes. Taken together, our data indicate that SCKH1PAIBPB can be proposed as an effective anti-inflammatory compound that may have a potential therapeutic use for the prevention and treatment of various inflammatory diseases as well as ischemic vascular diseases.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.4_1
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• pp.363-371
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• 2014

Most space-borne optical scanning systems adopt linear arrayconfigurations. The well-knownthree different types of space-borne sensors arealong-track line scanner, across-track linescanner, and three line scanner. To acquire accurate location information of an object on the ground withthose sensors, the exterior and interior orientation parameters are critical factors for both of space-borne and airborne missions. Since the imaging geometry of sensors mightchange time to time due to thermal influence, vibration, and wind, it is very important to analyze the Interior Orientation Parameters (IOP) effects on the ground. The experiments based on synthetic datasets arecarried out while the focal length biases are changing. Also, both high and low altitudes of the imagingsensor were applied. In case with the along-track line scanner, the focal length bias caused errors along the scanline direction. In the other case with the across-track one, the focal length bias caused errors alongthe scan line and vertical directions. Lastly, vertical errors were observed in the case ofthree-line scanner. Those results from this study will be able to provide the guideline for developing new linearsensors, so as for improving the accuracy of laboratory or in-flight sensor calibrations.

• Korean Journal of Food Science and Technology
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• v.46 no.3
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• pp.347-351
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• 2014

We studied the green synthesis and antibacterial activity of chitosan-silver (Ag) nanocomposite films for application in food packaging. Green synthesis of Ag nanoparticles (AgNPs) was achieved by a chemical reaction involving a mixture of chitosan-silver nitrate ($AgNO_3$) in an autoclave at 0.1 MPa, $121^{\circ}C$, for 15-120 s. The formation of AgNPs in chitosan was confirmed by both UV-Visible spectrophotometry and transmission electron microscopy (TEM) and the effects of chitosan-$AgNO_3$ concentration and reaction time on the synthesis of AgNPs in chitosan were examined. The resulting chitosan-Ag composite films were characterized by various analytical techniques and their antibacterial activity was evaluated based on the formation of halo zones around films, indicating inhibition of the growth of Escherichia coli. A fourier-transform infrared (FTIR) spectroscopy analysis showed that free amino groups in chitosan acted as effective reductants and AgNP stabilizers. The composite films exhibited enhanced antibacterial activity with increasing Ag content on the surface of as-prepared composite films.

• Journal of Food Hygiene and Safety
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• v.29 no.1
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• pp.6-15
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• 2014

This study was performed to acquire the information on the foodborne pathogen risk management programs in a couple of developed countries by the expert meeting and searching the information on the web. The backgrounds, strategies and effects related to microbial hazards of the foodborne pathogen reduction programs in fresh produce (US), Escherichia coli O157:H7 in ground beef (US), Salmonella in chicken, pork and eggs (Denmark), and Vibrio parahaemolyticus in seafood (Japan) were investigated for case study. A comparison among the pathogen reduction programs was conducted to find advantages and disadvantages and implications of the policies to bring out implications of the programs. A model for foodborne pathogen reduction program was developed based on both the CODEX risk management scheme and the case studies as follows; 1) preliminary risk management activities, 2) planing a foodborne pathogen reduction program, 3) option identification and selection, 4) implementation (conducting the each stake-holders role and applying the intervention methods), 5) monitoring activities, 6) interim review, 7) continuation or amendment of implementation method by the interim review before achieving the goal, and 8) final review and additional cost-benefit analysis if necessary. This proposed model according to the role of the stake-holders can be used to conduct microbial risk management programs in Korea in the near future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.3
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• pp.670-676
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• 2009

Bankruptcy of firms in Korea can cause distress of financial institutions because these institutions have disterssed bond. Accordingly, social and economical spill-over effects by these results are very big. Even after the difficult times of IMF crisis had ended, bankruptcy of information-based small-medium companies and venture firms listed on the KOSDAQ has been continued. In this context, this study developed and adopted failure prediction models for which discriminant analysis was used. Samples of this study was 81 firms respectively for both failed and non-failed firms listed on the KOSDAQ between the year of 2000 and 2007. The results of this study are as follows. First, the accuracy of classification of the model by years was $74.5%{\sim}76.5%$, and the accuracy of classification of the mean model was $69.6%{\sim}80.4%$. Among the models, the mean model of -one year, -two years, and -three years was highest in accuracy of classification (80.4%). Second, accuracy of prediction of final model adopted on validation samples showed 85% before one year of bankruptcy. The results of this study may be significant in that the results may be used as early warning system for bankruptcy prediction of KOSDAQ firms.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.1-11
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• 2016

The effect of the migration of nanoparticles near the wall of a channel on the convective heat transfer in a laminar flow of $SiO_2$ nanoparticle suspensions (nanofluids) under constant wall heat flux boundary conditions was numerically and experimentally investigated in this study. The dynamic thermal conductivity of the aqueous $SiO_2$ nanofluids was measured using T-type thermocouples attached to the outer surface of a stainless steel circular tube (with a length of 1 m and diameter of 1.75 mm). The nanofluids used in this study were synthesized by dispersing $SiO_2$ spherical nanoparticles with a diameter of 24 nm in de-ionized water (DIW). The enhancement of the thermal conductivity of the nanofluids (e.g., an increase of up to 7.9 %) was demonstrated by comparing the temperature profiles in the flow of the nanofluids with that in the flow of the basefluids (i.e., DIW). However, this trend was not demonstrated in the computational analysis, because the numerical models were based on continuum assumptions and flow features involving nanoparticles in a stable colloidal solution. Thus, to explore the non-continuum effects, such as the modification of the morphology caused by nanoparticle-wall interactions on the heat exchanging surfaces (e.g., the isolated and dispersed precipitation of the nanoparticles), additional experiments were performed using DIW right after the measurements using the nanofluids.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.1
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• pp.195-202
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• 2004

The shell due to the effect of initial normal pressures on the shell surface was based on the assumption that the directions of the pressures are always normal to the undeformed shell surface, and that the change in the surface area of the shell is negligible. But the fact that the pressure are always normal to the deforming surface leads "follower force". The follower effect in the analysis can significantly alter the solution for natural frequency and buckling load as compared to the case when the direction of the pressures are assumed to be normal to the uniform shell surface. The expression for the part of strain energy contribution from normal pressure due to the effect of follower force was derived and added to the element stiffness matrix of axisymmetric shell. In the case of increasing external pressure, the natural frequencies decrease until one of them reaches zero. Theoretically the smallest applied load that reduces the frequency of any mode to zero, will have same magnitude as that of the buckling load. In order to determine the bucking load of the shell a few sets of frequencies are computed and the results considering the follower effects are well with the exact solution while the case without that are quite different. But in case of hemispherical dome, there are little difference in buckling pressure between with and without the effect of follower force.

• Journal of dental hygiene science
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• v.16 no.2
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• pp.118-126
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• 2016

This study collected opinions about the design and management of toothbrushing facilities from schoolteachers and the people in charge of public centers, through a focus group interview (FGI), for the development of guidelines. Four moderators conducted eight FGIs of 32 subjects in charge of toothbrushing facilities across all the regions. The qualitative data was analyzed by constant comparative analysis. The findings indicated that more students utilized the facility and brushed their teeth after the installation of toothbrushing facilities. To enhance students' accessibility and safety, guidelines for design and management guidelinesfor toothbrushing facilities need to be developed; the location, sink height and depth, drain size, etc. should be comprehensively considered in the development of the guidelines. This study can help to improve students' satisfaction by enhancing the accessibility, safety, and functionality of toothbrushing facilities, and by providing fundamental data for toothbrushing facilities' development. Finally, this study can maximize the effects of management of toothbrushing facilities management on the improvement of students' oral health and behaviors.