• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.1D
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• pp.133-139
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• 2011

We built subway stops in order to meet demand. To do so, a standardized method is used to predict the demand. However, in some subway stops there are only few people moving around sparsely, but in some other stops there are too many people crammed in a crowd. The gap between forecasting and actual uses varies from 10% to more than 1,000%. This study is aimed to find out where this discrepancy between predicted vs. actual demand for urban rail transit comes from. Specifically, 40 subway stops in Seoul Metropolitan Area, which were opened last 10 years, are examined. This study suggests that, for better forecasting, we need to consider stops' locational characteristics as well as weekday commute-oriented exogenous factors. Locational characteristics includes; whether a stops is a terminal and/or weekend tourism node. There seems no "one size fits all" solution for transit demand forecasting; locational characteristics need to be reflected.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.6
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• pp.786-798
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• 2001

This paper describes the phenomena of wake-induced transition of the boundary layers on a NACA0012 airfoil using measured phase-averaged data. Especially, the phase-averaged wall shear stresses are reasonably evaluated using the principle of Computational Preston Tube Method. Due to the passing wake, the turbulent patch is generated in the laminar boundary layer on the airfoil and the boundary layer becomes temporarily transitional. The patches propagate downstream with less speed than free-stream velocity and merge with each other at further down stream station, and the boundary layer becomes more transitional. The generation of turbulent patch at the leading edge of the airfoil mainly depends on velocity defects and turbulent intensity profiles of passing wakes. However, the growth and merging of turbulent patches depend on local streamwise pressure gradients as well as characteristics of turbulent patches. In this transition process, the present experimental data show very similar features to the previous numerical and experimental studies. It is confirmed that the two phase-averaged mean velocity dips appear in the outer region of transitional boundary layer for each passing cycle. Relatively high values of the phase-averaged turbulent fluctuations in the outer region indicate the possibility that breakdown occurs in the outer layer not near the wall.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.5
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• pp.487-495
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• 2014

In this study, in order to suggest the design method for supports in the room-and-pillar underground structure, the case study was carried out. In the case study, shape of rock pillar and room was mainly considered. From the analysis, a displacement at the roof, the maximum principle stress and plastic state were examined. To optimize variables in the case study, cases from the Seoul metro station were analyzed, then a target depth of the underground structure and ground conditions were determined. And the height of rock pillar and room were chosen from the assumed purpose of underground space, i.e. living/office and warehouse. Total cases of analysis was 180 cases including 3 types of ground condition, 5 types of rock pillar and 6 types of roof span. It is expected that results from analysis can be used to determine the installation of support in room-and-pillar underground structure with stability, utilization efficiency of underground space and applicability of vehicles.

• Journal of the Korea Society of Computer and Information
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• v.19 no.12
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• pp.187-196
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• 2014

In this paper, Minimize driving energy for operation within a defined distance yeokgan fixed time-resolved and determine the nature of the train is traveling, and to model mathematically. Urban rail car cruise in general by the PID controller is used instead of automatically tracking a target value while traveling in energy consumption to be minimized by using optimal control model railroad charyangreul was designed under real operating conditions the same. The actual track conditions apply to the minimum value or a separate listing of cars around the track facility without a driving energy of the automatic operation and to reduce the driving energy. Therefore, actual route chosen straight line 8 / gradient segment / curve for the measured data analysis, such as sections within the city-minute drive each section and presented how the trains to save energy, depending on the pattern of the train station in the region.

• Korean journal of applied entomology
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• v.10 no.1
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• pp.7-12
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• 1971

1. The number of Rhizoctonia solani, Pythium debaryanum, Fusarium and Trichoderma was detected by the modification of Boosails special plating method when ginseng seed bed was drenched with Captan, Difolatan, Zineb, Maneb and PCNB at weekly intervals. Pythium debaryanum Hesse was described for the first time on Panax ginseng in Korea. 2. The number of Rhizoctonia solani and Pythium debaryanum was decreased gradually as the geason Progressed, whereas that of Fusarium and rrichcderma was increased. 3, The number of Rhixoctonia solani was greatly reduced by PCNB, and soils treated with other fungicides generally showed less Rhizoctonie solani than in the control. The number of Pythium debaryanum was significantly reduced by Zineb, Maneb, followed by Captan and Difolatan. None of the fungicids reduced the number of Fusarium colonies in the fourth week. Effects of the chemicals on Trichoderma were not statistically significant. 4. More fresh weight of the seedling roots was obtained using Difolatan, Maneb and PCNB. Phytotoxicity was noted with Maneb, Zineb and Captan after the third treatment.

• YAKHAK HOEJI
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• v.21 no.4
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• pp.200-210
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• 1977

This investigation was undertaken from February 1976 to September 1976. The detergents in municipal sewages from the Chung Kae Stream, Ahn Yang Stream, and Bong Won Stream were determined at 1.5ppm, 0.93ppm, and 3.36ppm in average respectively. The concentrations of detergents determined in the Han river were 0.013ppm of Kwang Na Ru, 0.11ppm of Duk Do, 0.370ppm of Bo Kwang Dong, and 0.285ppm of Ka Yang Dong basin respectively. And the potable waters of Sung Book Ku and Sung Dong Ku from Ku Eu water pumping station located up-stream of the Han river were less polluted at 0.045ppm and 0.037ppm in average. Young Deung Po Ku and Su Dae Moon Ku had been relatively polluted at 0.181ppm and 0.133ppm. The coagulant, alum [$Al_{2}(SO_{4})_{3}$] could eliminated the small amount of detergent by coagulation. The eliminated rates were about 13% by 5ppm and 22.7% by 20ppm of aluminum sulfate in sewage contained 10ppm of turbidity. The sand and the charcoal adsorbed some detergent as the following Langmuir's equations: For the charcoal, m/x=0.029.$\times$1/Ce-11.43 For the charcoal, m/x=2.705log1/Ce-5.46 Where m: amount of snad and active carbon used(g) x: amount of detergent adsorbed from liquid(g) Ce:concentration in the liquid at equilibrium(miles) The adsorption effect of sand would be neglected. In the low concentration of detergent solution, one gram of active carbon adsorbed 0.263g of detergent. It was determined that one gram of chlorine reduced 5.5g pf DBS om keeping up 0.2ppm of residual chlorine by disinfection process with chlorine compound.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1541-1550
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• 2007

A subway is one of many public transportation means that contributes toward our society including seoul and offering of its service and expression of various information are in need due to users high demand. And there are various class of users. For that reason an optical communication network in the general contorl center and station buildings was installed. Considering the importance of safe operation of subway, optical communication exists to enhance customer satisfaction. Safe operation is essential as its level of reliance accounts for about 95%. this paper will look for ways to promote mutual information interchange and operation know-how with systems of the same kind and sharing a capable of effective operation of systems in place. Optical communication network in the metropolis railroad accepts various kinds of control networks and data networks for train operation. As occasion demands, this paper presents effective application scheme and specialized organization about an optical communication operating system.

• Journal of Korea Water Resources Association
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• v.48 no.1
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• pp.37-44
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• 2015

A Bayesian nonstationary probability rainfall estimation model using the Grid method is developed. A hierarchical Bayesian framework is consisted with prior and hyper-prior distributions associated with parameters of the Gumbel distribution which is selected for rainfall extreme data. In this study, the Grid method is adopted instead of the Matropolis Hastings algorithm for random number generation since it has advantage that it can provide a thorough sampling of parameter space. This method is good for situations where the best-fit parameter values are not easily inferred a priori, and where there is a high probability of false minima. The developed model was applied to estimated target year probability rainfall using hourly rainfall data of Seoul station from 1973 to 2012. Results demonstrated that the target year estimate using nonstationary assumption is about 5~8% larger than the estimate using stationary assumption.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.10a
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• pp.27-27
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• 2003

Lake Texoma is located on the border of southern Oklahoma and northern Texas. It has 93,000 surface acres, and is a focus of the recreation, and farming industries in the region. There are potential stressors around the Lake Texoma watershed that may cause adverse ecological effects in the lake. System assimilative capacity (SAC) is the ability of abiotic and biotic processes to atteuniate the stressors. SAC Exceeded indicates potential of occuring adverse eco-effects. A number of representative chemical release sites and stressor sources in the surrounding watershed were characterized, and several impact sites having stressors sources, such as being near agriculture, landfills, housing areas, oil production fields and heavy use recreational activity, were selected for surface water, sediment, and groundwater monitoring. A paired reference site, having similar physical characteristics as its impact site, was also chosen based on its proximity to the impact site. Lake water samples were collected at locations identified as marina entrance, gasoline filling station, and boat dock at five marinas selected on Lake Texoma from September 1999 to December 2001. Paired water and sediment samples were also collected. Groundwater samples were collected at about 70 producing monitoring wells. Water quality parameters measured were inorganics (nitrate, nitrite, orthophosphate, ammonia, sulfate, and chloride), dissolved methane, total organic carbon (TOC) (or DOC), volatile organic compounds (VOCs) such as methyl tert-butyl ether (MTBE) and BTEX, and a suite of metals. Biotic communities were evaluated at impact and reference sites. Five basic components were measured; two terrestirial components (plants and bird comminitires) and three aquatic components (benthic inverbrates, litteral-zone fishes, ecosystem attribures). Potential impacts to these comminites were evaluated.

• Korean Journal of Remote Sensing
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• v.27 no.4
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• pp.411-420
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• 2011

In this study, a digital elevation model (DEM) in tidal flat of Suncheon Bay, one of the most ecological preserved area in the world, was generated from digital aerial stereo-images. The focal lengths for the aerial stereo-images were adjusted using ground control points (GCPs) in order to improve the accuracy of camera parameters. We proposed matching sizes suitable for generating DEM in tidal flat and a method for eliminating excessive position errors using intersection-distance($P_R$) threshold value. The accuracies of the DEM generated from the proposed method as well as the commercial S/W were compared with the elevation profiles measured by Total Station in the filed. As the results, the DEM generated by the proposed method showed better result (maximum deviation is a -21 centimeters) with detailed topography than DEM by the commercial S/W in the region. These results suggest that the DEM of tidal flat, which hardly obtained with the traditional methods, can be generated from digital aerial images by applying the proposed method in this study. We believe that the generated DEM in tidal flat can be an essential data for monitoring the sediment erosion and deposit of the tidal flat.