• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.2
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• pp.311-324
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• 2017

Energy loss at manholes under surcharged flow is considered as one of the major causes of inundation in urban area. Therefore, it is necessary to analyze the flow characteristics to reduce the energy loss in the surcharged four-way combining manhole. In this study, hydraulic experimental apparatus was constructed considering the results of the present survey. Square manholes and pipe diameters were reduced to 1/5 by applying sewer facility standards. Numerical simulations were carried out with the Fluent 6.3 model to derive the invert condition which can reduce the energy loss in the surcharged four-way combining square manhole. The hydraulic experiments were carried out according to the various conditions of the lateral flow rate($Q_{lat}/Q_{out}$), discharge of outflow pipe (2.0, 3.0, 4.0, 4.8 l/sec), and invert shape (rectangle and square open conduit type). The crossed invert was not found to improve the drainage capacity of the surcharged four-way rectangular combining manhole. However, the improved rectangle open conduit type invert and square open conduit type invert were analyzed to improve the drainage capacity by reducing the head loss coefficients by about 8% and 28%, respectively. Therefore, in order to increase the drainage capacity of urban facilities, it is possible to install and use the improved invert proposed in this study.

• Investigative Magnetic Resonance Imaging
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• v.3 no.2
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• pp.188-195
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• 1999

The fMRI signals are composed of many various signals. It is very difficult to find the accurate parameter for the model of fMRI signal containing only neural activity, though we may estimating the signal patterns by the modeling of several signal components. Besides the nose by the physiologic motion, the motion of object and noise of MR instruments make it more difficult to analyze signals of fMRI. Therefore, it is not easy to select an accurate reference data that can accurately reflect neural activity, and the method of an analysis of various signal patterns containing the information of neural activity is an issue of the post-processing methods for fMRI. In the present study, fMRI data was analyzed with the Independent Component Analysis(ICA) method that doesn't need a priori-knowledge or reference data. ICA can be more effective over the analytic method using cross-correlation analysis and can separate the signal patterns of the signals with delayed response or motion related components. The Principal component Analysis (PCA) threshold, wavelet spatial filtering and analysis of a part of whole images can be used for the reduction of the freedom of data before ICA analysis, and these preceding analyses may be useful for a more effective analysis. As a result, ICA method will be effective for the degree of freedom of the data.

• The Journal of Engineering Geology
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• v.29 no.4
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• pp.439-449
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• 2019

To prevent the drying-out of streams and to make effective use of stream water and groundwater, it is necessary to evaluate the impact of groundwater pumping on nearby streams. To this end, stream depletion due to groundwater pumping should be investigated in terms of various hydraulic characteristics of the aquifer and stream. This study used the Baalousha analytical solution, which accounts for stream-stage variation over time, to analyze stream depletion due to groundwater pumping for cases where the stream level decreases exponentially and recovers after the decrease. For conditions such as an aquifer transmissivity of 10~100 ㎡ d^-1, storage coefficient 0.05~0.3, streambed hydraulic conductance 0.1~1.0 m d^-1, stream-well distance 100~500 m, and stage recession coefficient 0.1~1.0 d^-1, the contribution of stream water (the dimensionless ratio of stream water reduction rate to groundwater pumping rate) was analyzed in cases where stream level change was considered. Considering the effect of stream-stage recession, the contribution of stream water is greatly reduced and is less affected by the stream-depletion factor, which is a function of the stream-to-well distance and hydraulic diffusivity. However, there is no significant difference in stream depletion under constant- and variable-stage recovery after recession. These results indicate that stream level control can distribute the relative impacts on stream water and aquifer storage during groundwater pumping

• Ecology and Resilient Infrastructure
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• v.3 no.3
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• pp.207-211
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• 2016

This study focuses on the categorization of the phenomenon of vegetative recruitment on riparian channels, so called, the phenomenon from "white river" to "green river", and proposes for the corresponding research direction. According to the literature review and research outputs obtained from the authors' previous research performed in Korea within a limited scope, the necessary and sufficient conditions for the recruitment and retrogression of riparian vegetation may be the mechanical disturbance (riverbed tractive stress), soil moisture (groundwater level, topography, composition of riverbed material, precipitation etc.), period of submergence, extreme weather, and nutrient inflow. In this study, two categories, one for the reduction in spring flood due to the change in spring precipitation pattern in unregulated rivers and the other for the increase in nutrient inflow into streams, both of which were partially proved, have been added in the categorization of the vegetative recruitment and retrogression on the riparian channels. In order to scientifically investigate further the phenomenon of the riparian vegetative recruitment and retrogression and develop the working riparian vegetative models, it is necessary to conduct a systematic nationwide survey on the "white to green" rivers, establishment of the categorization of the vegetation recruitment and retrogression based on the proof of those hypotheses and detailed categorization, development of the working mathematical models for the dynamic riparian vegetative recruitment and retrogression, and adaptive management for the river changes.

• Korean Journal of Food Science and Technology
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• v.49 no.2
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• pp.192-202
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• 2017

In this study, factors involved in lipid and energy metabolism following treatment with ethanolic extract of the Polygonatum sibiricum rhizome (ID1216) were evaluated in high-fat diet-induced obese mice. ID1216-treated mice showed a significant reduction in weight gain compared to non-treated mice. ID1216 treatment increased the protein levels of AMP-dependent protein kinase, sirtuin1, peroxisome proliferator-activated receptor ${\gamma}$ coactivator 1-${\alpha}$ ($PGC1{\alpha}$), peroxisome proliferator-activated receptor ${\alpha}$ ($PPAR{\alpha}$) and uncoupling proteins in the adipose tissue, liver and muscle compared to vehicle treatment. Analysis of downstream signals of the sirtuin1 $PGC1{\alpha}$-$PPAR{\alpha}$ pathway showed that ID1216 regulates the expression of ${\beta}$-oxidation related genes such as acyl-CoA oxidase, carnitine palmitoyltransferase1, acyl-CoA dehydrogenase and adipocyte protein 2. In addition, ID1216 increased the expression of adipose triglyceride lipase. These results suggest that ID1216 has anti-obesity effects by regulating the genes involved thermogenesis, ${\beta}$-oxidation and lipolysis in a diet-induced obesity model.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.5
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• pp.355-361
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• 2020

Among these satellites, low - orbit small satellites with military characteristics require multi - target observation, and demand for high-resolution photographs and images is increasing. Fast maneuverability is the most important factor for high-resolution images and multi - target observations. However, in the case of a small satellites, it is possible to perform the attitude maneuver if it has high speed, but the residual vibration occurs when the attitude maneuver is completed and the next attitude maneuver is completed. In this study, to verify the vibration characteristics of the plate generated after attitude maneuver, an experimental fixture for simulating the attitude maneuver was fabricated and tested. In addition, Eddy Current Damper (ECD) using Eddy Current Brake system (ECB) is proposed as a passive damping method using permanent magnet to reduce vibration. A mathematical model was established to apply ECD and it was experimentally implemented according to the magnetic flux density and the air gap of the permanent magnet. One plate of four solar panels (plate) was specified, the residual vibration reduction performance after the test was verified experimentally.

• The Korean Journal of Food And Nutrition
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• v.25 no.4
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• pp.787-792
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• 2012

The objective of this study was to investigate the proper concentration of D-xylose which is expected to reduce the GI (Glycemic index) value of sucrose in the human body. When subjects took a sucrose mixture containing 5% and 10% D-xylose, the blood glucose levels were lowered by approximately 27.5% and 25.9%, respectively, compared to those of sucrose. The GI values of sucrose mixtures containing 5% and 10% D-xylose were 49.3 and 50.4, respectively. The reduction in GI value was not dependent on the D-xylose concentration, as the GI value of sucrose mixture containing 5% D-xylose (XyloSugar) was similar to that of sucrose mixture containing 10% D-xylose (XyloSugar10). D-xylose is not only more expensive but also less sweet than sucrose. So, low concentration of D-xylose has the advantage in the price and taste. It was determined that the proper concentration of D-xylose expected to reduce GI value of sucrose was 5% (w/w).

• Korean Journal of Food Science and Technology
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• v.22 no.4
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• pp.445-450
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• 1990

Changes in weight, volume and density of petiole tissue of Chinese cabbage during salting and blanching were investigated. Rapid changes in mass and volume occurred within 4 hours during salting in 5% salt solution and the changes were nearly completed after 8h. After salting, the reduction of mass and volume ranged between $22{\sim}27%\;and\;22{\sim}35%$, respectively. Average density of the sample was found to be 0.88g/ml, and increased to 1.020g/ml after salting. Air content of the sample ranged from 0.093 to 0.120ml/ml cabbage, and about 70% of the initial content was expelled from the tissue by salting. The changes of physical properties of the cabbage during steam blanching were similar to those during salting, but their relative values were smaller. A linearization model for physical changes during salting and blanching was proposed.

• Korean Journal of Biological Psychiatry
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• v.10 no.2
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• pp.168-176
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• 2003

Objectives:We investigated the characteristics of P300 generators in obsessive-compulsive disorder(OCD) patients by using voxel-based statistical parametric mapping of current density images. Methods:P300 generators, produced by a rare target tone of 1500Hz under a frequent non-target tone of 1,000Hz, were measured in 15 right-handed OCD patients and 15 controls. Low Resolution Electromagnetic Tomography(LORETA), using a realistic head model of the boundary element method based on individual MRI, was applied to the 128-channel EEG. Statistical parametric mapping(SPM) was applied for the statistical analysis. Results:We found that both groups had the mean current density of P300 in the parietal, temporal and prefrontal lobe. There was a trend for decreased current density in the prefrontal area in OCD patients. The statistical comparison showed current density increase in the supraparietal area, a statistically significant longer P300 latency and a trend for reduced P300 amplitude in OCD patients. Conclusion:It suggests that P300 source of both groups exists in multiple brain regions at the same time. And both groups had no statistically significant differences in the current density of P300 except for increased current density in the supraparietal area in OCD patients. But, considering the statistically significant longer P300 latency, a trend for reduced P300 amplitude and relative mean current density reduction in the prefrontal area in OCD patients, this study suggests that the frontal lobe may have a reduced normal inhibitory process in OCD patients.

• Tunnel and Underground Space
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• v.26 no.2
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• pp.59-67
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• 2016

In this paper, we perform a numerical analysis to evaluate the potential of fault reactivation during gas production from hydrate bearing sediments and the moment magnitude of induced seismicity. For the numerical analysis, sequential coupling of TOUGH+Hydrate and FLAC3D was used and the change in effective stress and consequent geomechanical deformation including fault reactivation was simulated by assuming that Mohr-Coulomb shear resistance criterion is valid. From the test production simulation of 30 days, we showed that pore pressure reduction as well as effective stress change hardly induces the fault reactivation in the vicinity of a production well. We also investigated the influence of stress state conditions to a fault reactivation, and showed that normal fault stress regime, where vertical stress is relatively greater than horizontal, may have the largest potential for the reactivation. We tested one simulation that earthquake can be induced during gas production and calculated the moment magnitude of the seismicity. Our calculation presented that all the magnitudes from the calculation were negative values, which indicates that induced earthquakes can be grouped into micro-seismic and as small as hardly perceived by human beings. However, it should be noted that the current simulation was carried out using the highly simplified geometric model and assumptions such that the further simulations for a scheduled test production and commercial scale production considering complex geometric conditions may produce different results.