• Wind and Structures
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• v.8 no.6
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• pp.427-442
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• 2005

Numerical and wind tunnel simulations of pollutant dispersion around rectangular obstacles with five aspect ratios have been conducted in order to identify the effects of flow patterns induced by buildings on plume dispersion in the near wake of buildings. An emission from a low source located upwind of obstacles was used in this simulation. The local flow patterns and concentrations around a cubical obstacle were initially investigated using three RANS turbulence models, (the standard $k-{\varepsilon}$, Shear Stress Transport (SST), Reynolds-Stress RSM turbulence model) and also using Large-eddy simulation (LES). The computed concentrations were compared with those measured in the wind tunnel. Among the three turbulence models, the SST model offered the best performance and thus was used in further investigations. The results show, for normal aspect ratios of width to height, that concentrations in the near wake are appreciably affected because of plume capture by the horseshoe vortex and convection by the vertical vortex pairs. These effects are less important for high aspect ratios. Vertical vortex pairs present a strong ability to exchange mass vertically and acts efficiently to reduce ground-level concentrations in the near wake.

• Smart Structures and Systems
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• v.12 no.1
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• pp.1-22
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• 2013

Magnetic nanoparticle based bioseparation in microfluidics is a multiphysics phenomenon that involves interplay of various parameters. The ability to understand the dynamics of these parameters is a prerequisite for designing and developing more efficient magnetic cell/bio-particle separation systems. Therefore, in this work proof-of-concept experiments are combined with advanced numerical simulation to design and optimize the capturing process of magnetic nanoparticles responsible for efficient microfluidic bioseparation. A low cost generic microfluidic platform was developed using a novel micromolding method that can be done without a clean room techniques and at much lower cost and time. Parametric analysis using both experiments and theoretical predictions were performed. It was found that flow rate and magnetic field strength greatly influence the transport of magnetic nanoparticles in the microchannel and control the capturing efficiency. The results from mathematical model agree very well with experiments. The model further demonstrated that a 12% increase in capturing efficiency can be achieved by introducing of iron-grooved bar in the microfluidic setup that resulted in increase in magnetic field gradient. The numerical simulations were helpful in testing and optimizing key design parameters. Overall, this work demonstrated that a simple low cost experimental proof-of-concept setup can be synchronized with advanced numerical simulation not only to enhance the functional performance of magneto-fluidic capturing systems but also to efficiently design and develop microfluidic bioseparation systems for biomedical applications.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.12
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• pp.904-908
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• 2013

When an abnormal condition occurs due to a fault current at a consumer location where electricity is supplied through a high-capacity and high-$T_c$ superconducting(HTS) cable, the HTS cable would be damaged if there is no appropriate measure to protect it. Therefore, appropriate measures are needed to protect HTS cables. The fault-current-limiting HTS cable that was suggested in this study performs an ideal transport current function in normal operations and plays a role in limiting a fault current in abnormal operation (i.e., when a fault current is applied). It has a structure that facilitated its self-current-limiting ability through device change and reconfiguration in the existing HTS cable without extra switching equipment. To complete this structure, it is essential to investigate about the selection of the superconducting wire. Therefore, in this paper, HTS wire using two types of different stabilization layer is compared and examined the stability and current limiting properties under the existence of a fault current.

• BMB Reports
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• v.48 no.3
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• pp.139-146
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• 2015

Adaptive brain function and synaptic plasticity rely on dynamic regulation of local proteome. One way for the neuron to introduce new proteins to the axon terminal is to transport those from the cell body, which had long been thought as the only source of axonal proteins. Another way, which is the topic of this review, is synthesizing proteins on site by local mRNA translation. Recent evidence indicates that the axon stores a reservoir of translationally silent mRNAs and regulates their expression solely by translational control. Different stimuli to axons, such as guidance cues, growth factors, and nerve injury, promote translation of selective mRNAs, a process required for the axon's ability to respond to these cues. One of the critical questions in the field of axonal protein synthesis is how mRNA-specific local translation is regulated by extracellular cues. Here, we review current experimental techniques that can be used to answer this question. Furthermore, we discuss how new technologies can help us understand what biological processes are regulated by axonal protein synthesis in vivo.

• Journal of Soil and Groundwater Environment
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• v.18 no.7
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• pp.25-31
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• 2013

Hydrogen peroxide takes much of the cost for Fenton reaction applied for treatment of organic contaminants. Therefore, the effective use of hydrogen peroxide makes the technology more cost effective. The effective use of hydrogen peroxide is especially needed in the soil and groundwater remediation where complete mixing is not possible and it takes a long time for reactive species to transport to the fixed target compounds. Stabilization ability for hydrogen peroxide of malonic acid was evaluated in Fenton and Fenton-like reactions in this study. Malonic acid contributes on the stabilization of hydrogen peroxide by weak interaction between iron and the stabilizer and inhibiting the catalytic role of iron. The stabilization effect increased as the solution pH decrease below the $pK_{a1}$. The stabilization effect increased as the concentration of malonic acid increased and the effect was maximized at the malonic acid concentration of about ten times higher than the iron concentration. The model organic contaminant was successfully oxidized in the presence of the stabilizer but the degradation rate was slower than the system without the stabilizer. The stabilization effect was also proved in a Fenton-like reaction where magnetite and hematite were used instead of soluble iron species.

• Journal of Korea Technology Innovation Society
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• v.1 no.1
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• pp.96-105
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• 1998

Electronic cash affects central bank in many areas, in particular regarding the issuance of money, supervision of cashless payments, supervision of the banking system and monetary policy. The effects of electronic cash on central bank policies, the security and integrity of the payment system, and naturally also on single sector such as company engaged in the transport of money and valuables, depend mainly on the extent to which the new payment methods can replace cash. The possible development of electronic cash merits special attention from central banks for at least three reasons. First, central banks are concerned that the introduction of the new payment instrument should have no adverse effect on public confidence in the payment system and payment media. Second, although the substitution of electronic cash for other forms of money should not theoretically hamper central bank's ability to control the money supply, it might, however, have practial implications, at least in the long run, which need to be carefully examined. Third, because electronic cash may be used for payments of very small value, they have the potential, more than any other cashless instrument, to take over the role of notes and coins in the economy and, therefore, have implications for central bank's activities and revenues.

• Journal of Pharmaceutical Investigation
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• v.23 no.3
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• pp.19-30
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• 1993

The influence of emulsion type of tegafur, an oral anticancer agent, on lymphatic transport was studied in rats. The water-in-oil-type of emulsion and the oil-in-water-type emulsion of tegafur each in 50 mg, calculated in terms of tegafur, were prepared by adding tegafur aqueous solution to sesame oil containing hydrogenated castor oil following ultrasonic treatment, and then the prepared emulsions and aqueous solution as a comparative formulation were administered orally to rats (50 mg/5 ml/kg). The concentration levels of tegafur in plasma of femoral artery and lymph from thoracic duct cannula were measured simultaneously along a time course after administration and the pharmacokinetic parameters were investigated. At the same time, we examined the above described factors of 5-FU which is known as an active metabolite of tegafur. In comparison with tegafur solution, AUC and mean residence time of plasma tegafur were significantly increased in w/o-emulsion but significantly decreased in o/w-emulsion. Lymph flow rates were similar in both solution and w/o-emulsion but half in o/w-emulsion. Ratios between area under the lymph and plasma concentration time curves were always less than 1 reflecting the passive lymphatic delivery after oral administration of the prepared tegafur emulsions, but those to the 5-FU in the case of w/o-emulsion were more than 1. These results suggested that lymphatic delivery of tegafur by w/o-emulsion was more effective than that by o/w-emulsion due to its differences of formation ability of chylomicrons.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.1
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• pp.1-11
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• 1999

Hyrdogenated amorphous silicon thin film transistors are used as a pixel switching device of TFT-LCDs and very active research works on a-Si:H TFTs are in progress. Further development of the technology based on a-Si:H TFTs depends on the increased understanding of the device physics and the ability to accurately simulate the characteristics of them. A two-dimensional device simulator based on the realistic and flexible physical models can guide the device designs and their optimizations. A non-uniform finite-difference TFT Simulation Program, TFT2DS has been developed to solve the electronic transport equations for a-Si:H TFTs. In TFT2DS, many of the simplifying assumptions are removed. The developed simulator was used to calculate the transfer and output characteristics of a-Si:H TFTs. The measured data were compared with the simulated ones for verifying the validity of TFT2DS. Also the transient behaviors of a-Si:H TFTs were calculated even if the values of the related parameters are not accurately specified.

• Journal of Environmental Impact Assessment
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• v.18 no.6
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• pp.347-357
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• 2009

This study conducted a vulnerability assessment on Korea's physical infrastructure to provide base data for developing strategies to strengthen Korea's ability to adapt to climate change. The assessment was conducted by surveying professionals in the field of infrastructure and climate change science. A vulnerability assessment was carried out for seven climate change events: average temperature increases, sea level rise, typhoons and storm surges, floods and heavy rain, drought, severe cold, and heat waves. The survey asked respondents questions with respect to the consequences of each climate change event, the urgency of adaptation to climate change, and the scale of investment for adaptation to each climate change event. Thereafter, management priorities for infrastructure were devised and implications for policy development were suggested. The results showed that respondents expected the possibility of "typhoons and storm surges" and "floods and heavy rain" to be the most high. Respondents indicated that infrastructure related to water, transportation, and the built environment were more vulnerable to climate change. The most vulnerable facilities included river related facilities such as dams and riverbanks in the "water" category and seaports and roads in the "transport and communication" category. The results found were consistent with the history of natural disasters in Korea.

• The Korean Journal of Nuclear Medicine
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• v.20 no.1
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• pp.33-37
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• 1986

It is well known that $^{99m}Tc-sulfur$ colloid or phytate hepatic scintigraphy is highly sensitive but not specific. Both $^{99m}Tc-DISIDA$ and bilirubin have been shown to share the same anionic transport pathway in the liver. Hepatocellular carcinoma(HCC) retains the ability to produce bile but has marked limitation to excreting it resulting in accumulation of bile within the tumor cells. Based upon such a fact, $^{99m}Tc-DISIDA$ hepatobiliary scintigraphy is used for the diagnosis of HCC. The present communication deals with our experience of DISIDA scintigraphic exploration of 9 cases of HCC in a retrospective way. We have made an observation on intensity of positive radio nuclide accumulation in the cold area of HCC as it is demonstrated by phytate scintigraphy. In addition we have semi quantitatively analyzed time-activity pattern and the following results were obtained. (1) All of 9 cases showed an increased uptake of $^{99m}Tc-DISIDA$ in delayed scintigrams. Of these 5 cases showed accumulation less than, 3 equal to, 1 more than the surrounding liver tissue. (2) The mean of the first appearing time of $^{99m}Tc-DISIDA$ activity in tumoral region was 2 hours and 20 minutes. (3) DISIDA scintigraphy provides us with positive informations of diagnostic value.