• Journal of the Korean Geotechnical Society
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• v.22 no.5
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• pp.59-67
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• 2006

The centrifuge and 1-g shaking table tests were performed simultaneously to compare the dynamic behaviors of loose sands of the same geotechnical properties. The prototype soils were 10 m thick liquefiable loose sands. The geometric scaling factors were 20 for 1-g and 40 for centrifuge tests. The excess pore pressure, surface settlement, and acceleration in the soil were measured at the same locations in the 1-g and centrifuge tests. The total excess pore pressure from development to dissipation was measured. In the centrifuge test, viscous fluid was used as the pore water to eliminate the time scaling difference between dynamic time and dissipation time. In the 1-g tests, the steady state concept was applied to determine the unit weight of the model soil, and two different time scaling factors were applied for the dynamic time and the dissipation time. It is concluded that the 1-g tests can simulate the excess pore pressure of the prototype soil if the permeability of the model soil is small enough to prevent dissipation of excess pore pressure during shaking and the dissipation time scaling factor is properly determined.

• Journal of Korean Society of Transportation
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• v.29 no.5
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• pp.121-138
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• 2011

More affordable and available cutting-edge technologies (e.g., wireless vehicle communication) are regarded as a possible alternative to the fixed infrastructure-based traffic information system requiring the expensive infrastructure investments and mostly implemented in the uninterrupted freeway network with limited spatial system expansion. This paper develops an advanced decentralized traveler information System (ATIS) using vehicle-to-vehicle (V2V) communication system whose performance (drivers' travel time savings) are enhanced by three complementary functions (autonomous automatic incident detection algorithm, reliable sample size function, and driver behavior model) and evaluates it in the typical $6{\times}6$ urban grid network with non-recurrent traffic state (traffic incident) with the varying key parameters (traffic flow, communication radio range, and penetration ratio), employing the off-the-shelf microscopic simulation model (VISSIM) under the ideal vehicle communication environment. Simulation outputs indicate that as the three key parameters are increased more participating vehicles are involved for traffic data propagation in the less communication groups at the faster data dissemination speed. Also, participating vehicles saved their travel time by dynamically updating the up-to-date traffic states and searching for the new route. Focusing on the travel time difference of (instant) re-routing vehicles, lower traffic flow cases saved more time than higher traffic flow ones. This is because a relatively small number of vehicles in 300vph case re-route during the most system-efficient time period (the early time of the traffic incident) but more vehicles in 514vph case re-route during less system-efficient time period, even after the incident is resolved. Also, normally re-routings on the network-entering links saved more travel time than any other places inside the network except the case where the direct effect of traffic incident triggers vehicle re-routings during the effective incident time period and the location and direction of the incident link determines the spatial distribution of re-routing vehicles.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.3
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• pp.143-156
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• 2015

In order to understand the dynamic characteristics of water column environments in the Western Pacific seamount area (approximately $150.2^{\circ}E$, $20^{\circ}N$), we investigated the water mass and the behavior of water column parameters such as dissolved oxygen, inorganic nutrients (N, P), and chlorophyll-a. Physico-chemical properties of water column were obtained by CTD system at the nine stations which were selected along the east-west and south-north direction around the seamount (OSM14-2) in October 2014. From the temperature-salinity diagram, the main water masses were separated into North Pacific Tropical Water and Thermocline Water in the surface layer, North Pacific Intermediate Water in the intermediate layer, and North Pacific Deep Water in the bottom layer, respectively. Oxygen minimum zone (OMZ, mean $O_2$ $73.26{\mu}M$), known as dysoxic condition ($O_2<90{\mu}M$), was distributed in the depth range of 700~1,200 m throughout the study area. Inorganic nutrients typified by nitrite + nitrate and phosphate showed the lowest concentration in the surface mixed layer and then gradually increased downward with representing the maximum concentration in the OMZ, with lower N:P ratio (13.7), indicating that the nitrogen is regarded as limiting factor for primary production. Vertical distribution of water column parameters along the east-west and south-north station line around the seamount showed the effect of bottom water inflowing at around 500 m deep in the western and southern region, and concentrations of water column parameters in the bottom layer (below 2,500 m deep) of the western and southern region were differently distributed comparing to those of the other side regions (eastern and northern). The value of Excess N calculated from Redfield ratio (N:P=16:1) represented the negative value throughout the study area, which indicated the nitrogen sink dominant environments, and relative higher value of Excess N observed in the bottom layer of western and southern region. These observations suggest that the topographic features of a seamount influence the circulation of bottom current and its effects play a significant role in determining the behavior of water column environmental parameters.

• The KIPS Transactions:PartD
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• v.15D no.2
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• pp.223-234
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• 2008

Recently the web service area provides the efficient integrated environment of the internal and external of corporation and enterprise that wants the introduction of it is increasing. Also the web service develops and the new business model appears, the domestic enterprise environment and e-business environment are changing caused by web service. The web service which provides the similar function increases, most the method which searches the suitable service in demand of the user is more considered seriously. When it needs to choose one among the similar web services, service consumer generally needs quality information of web service. The problem, however, is that the advertised QoS information of a web service is not always trustworthy. A service provider may publish inaccurate QoS information to attract more customers, or the published QoS information may be out of date. Allowing current customers to rate the QoS they receive from a web service, and making these ratings public, can provide new customers with valuable information on how to rank services. This paper suggests the agent-based quality broker architecture which helps to find a service providing the optimum quality that the consumer needs in a position of service consumer. It is able to solve problem which modify quality requirements of the consumer from providing the architecture it selects a web service to consumer dynamically. Namely, the consumer is able to search the service which provides the optimal quality criteria through UDDI browser which is connected in quality broker server. To quality criteria value decision of each service the user intervention is excluded the maximum. In the existing selection architecture, the objective evaluation was difficult in subjective class of service selecting of the consumer. But the proposal architecture is able to secure an objectivity with the quality criteria value decision where the agent monitors binding information in consumer location. Namely, it solves QoS information of service which provider does not provide with QoS information sharing which is caused by with feedback of consumer side agents.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.11 no.1
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• pp.12-20
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• 2008

Purpose: Chronic pulmonary disease may be caused by aspiration of gastric contents secondary to gastroesophageal reflux. At present, there is no gold standard for documenting pulmonary aspiration. The purpose of this study was to investigate the usefulness of radionuclide scintigraphy in the detection of gastroesophageal reflux and pulmonary aspiration. Methods: Thirty-five patients with suspected aspiration pneumonia, and five normal control subjects, were included in the study. All subjects underwent gastroesophageal reflux scintigraphy after the ingestion of a $^{99m}Tc$-tin colloid mixture. Dynamic images to detect gastroesophageal reflux were obtained for 1 hour. Additional static images of the chest, to detect lung aspiration, were obtained at 6 and 24 hours after oral ingestion of the tin colloid. In addition to visual analysis, pulmonary aspiration was quantitated by counting the number of pixels labeled with radioactive isotope in the region of interest (ROI) of both lung fields. Aspiration index (AI) was obtained by subtracting the pixel counts of the background from the pixel counts of the ROI. Results: Among 35 patients with suspected aspiration pneumonia, 23 proved to have gastroesophageal reflux by scintigraphy. One patient showed definite pulmonary accumulation of activity by visual analysis of the 6-hour image. Thirty of 35 (85.7%) patients showed higher AI beyond the upper limit of AI in the healthy controls. When we compared the reflux group with the non-reflux group, there was a significantly higher AI at 6 hours in the reflux group (p<0.05). Conclusion: The results suggest that radionuclide scintigraphy is useful in detecting small pulmonary aspiration in patients with suspected aspiration pneumonia secondary to reflux.

• Economic and Environmental Geology
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• v.54 no.6
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• pp.709-716
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• 2021

In this study, an adsorbent prepared by natural drying of iron hydroxide-based sludge collected from settling basin at a mine drainage treatment facility located in Gangneung, Gangwon-do was used to remove fluoride in an artificial fluoride solution and mine drainage, and the adsorption characteristics of the adsorbent were investigated. As a result of analyzing the chemical composition, mineralogical properties, and specific surface area of the adsorbent used in the experiment, iron oxide (Fe₂O₃) occupies 79.2 wt.% as the main constituent, and a peak related to calcite (CaCO₃) in the crystal structure analysis was analyzed. It was also identified that an irregular surface and a specific surface area of 216.78 m²·g^-1. In the indoor batch-type experiment, the effect of changes in reaction time, pH, initial fluoride concentration and temperature on the change in adsorption amount was analyzed. The adsorption of fluoride showed an adsorption amount of 3.85 mg·g^-1 16 hours after the start of the reaction, and the increase rate of the adsorption amount gradually decreased. Also, as the pH increased, the amount of fluoride adsorption decreased, and in particular, the amount of fluoride adsorption decreased rapidly around pH 5.5, the point of zero charge at which the surface charge of the adsorbent changes. Meanwhile, the results of the isotherm adsorption experiment were applied to the Langmuir and Freundlich isotherm adsorption models to infer the fluoride adsorption mechanism of the used adsorbent. To understand the thermodynamic properties of the adsorbent using the Van't Hoff equation, thermodynamic constants 𝚫H° and 𝚫G° were calculated using the adsorption amount information obtained by increasing the temperature from 25℃ to 65℃ to determine the adsorption characteristics of the adsorbent. Finally, the adsorbent was applied to the mine drainage having a fluoride concentration of about 12.8 mg·L^-1, and the fluoride removal rate was about 50%.