• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.30 no.2
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• pp.30-39
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• 1998

Effect of cationic starches and anionic colloidal silica on retention and drainage characteristics of Compozil system was investigated. Depending upon the degree of substitution and molecular weight of cationic starches and morphological characteristics of anionic colloidal silica, retention and drainage properties of Compozil system were significantly influenced. When cationic starch addition level increased above a certain limit retention and stock freeness were decreased. To elucidate this an electrostatic coagulation mechanism occurring between unadsorbed starch molecules and anionic colloidal silica was proposed. Unstructured colloidal silica showed greater improvement in retention than structured colloidal silica. Cationic corn starches with different degree of substitution and molecular weights were prepared and their effect as a constituent of Compozil system was also evaluated. By controlling the molecular weight and degree of substitution of cationic corn starch it was possible to achieve significant improvement in fines retention. Cationic corn starch with higher degree of substitution maintained its retention efficiency even when the stock conductivity was increased. Turbidity measurement technique was found to be a simple and useful method to measure the retention characteristics.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.417-424
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• 2005

Observed field behaviors are frequently different from the behaviors predicted in the design state due to several uncertainties involved in soil properties, numerical modelling, and error of measuring system even though a sophisticated numerical analysis technique is applied to solve the consolidation behavior of drainage-installed soft deposits. In this study, genetic algorithms are applied to back-analyze the soil properties using the observed behavior of soft clay deposit composed of multi layers that shows complex consolidation characteristics. Utilizing the program, one might be able to appropriately predict the subsequent consolidation behavior from the measured data in an early stage of consolidation of multi layered soft deposits. Example analyses for drainage-installed multi-layered soft deposits are performed to examine the applicability of proposed back-analysis method.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1369-1376
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• 2005

In case of the drainage type tunnel, the residual water pressure is likely to act on the tunnel lining due to the decrease of water-passing capacity of the filter material. Therefore, this study discussions a method to predict the lining load with the consideration of water passing capacity of the filter material through the literature review and numerical analysis. It is expected from the results of case studies that the design load acting on the concrete lining in the drainage type tunnel could be assumed to be about 50% of the hydrostatic water pressure in steady-state ground-water condition.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.1
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• pp.10-16
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• 1999

Air froth flotation was applied to OCC recycling process as a new pulp fractionation method and the effects of strength and drainage properties of testliner were also investigated. Fines including inks, stickies, and inorganic substances in OCC stock furnish were efficiently separated by the flotation. After the flotation, selective enzymatic treatment on the flotation reject was separately preformed, and then, the refined long fiber(flotation accept) portion was combined again with the fines(flotation reject) fraction for papermaking. This combination process was found to be effective in improving strength and drainage properties of testliner based on 100% OCC.

• Journal of Environmental Science International
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• v.9 no.3
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• pp.193-199
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• 2000

This study is carried out the analysis of the runoff characteristics for the design of the interior drainage systems by SWMM in urbanization basin. The basin analyzed in this study is Bumuh-chun basin which is located in Susung-gu of Taegu city. Huff method is used for rainfall distribution analysis. The optimal rainfall duration in Bumuh-chun basin is analyzed as about 90 minutes decided from comparison of arrival time and critical duration. Flood flow variation pattern is proposed through the comparison of the results of peak flow and peak time analyzed by SWMM about pre-urbanization and post-urbanization of Bumuh-chun basin. It is known that the variation of arrival time caused by the rapid increase of pavement rate in the upper area shows about 20∼25 minutes faster than pre- urbanization. Therefore, the management of surface water for design of water supply and drainage, and channel alteration has to considered the variation of geological factors according to urbanization.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.11a
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• pp.119-123
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• 2007

Recently, the green roofs market is active, but most constructors use former waterproofing method. So there are a lot of problems in the sub-organization of the green roofs system. I studied to use the block panel for the sub-organization of the green roofs system and I tested about the effectiveness of waterproofing, root barrier, drainage, and insulation. I have not found any problems about waterproofing, root barrier, drainage, and insulation in the results. The sub-organization of the green roofs system using the block panel is effective for waterproofing, root barrier, drainage, and insulation. We can apply it to the dried and unified execution technology.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.601-612
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• 2005

In mountainous area, Two parallel tunnels have been usually recognized as a road tunnel which has benefits in aspects of cost and stability. However, Design and construction of 2-Arch road tunnel are growing recently due to environmental destruction, compensation of land and difficulty of route separation. As studies are mainly undergoing on only guaranteeing stability and developing a waterproofing-drainage system to avoid water leakage through comprehension for characteristics of 2-arch tunnel behaviors, there is a tendency to evaluate quantity of support by empirical method with a tunnel which has a complicated cross-section and lack of construction ability. In this study, therefore, we made a plan of tunnel cross-section which had shown good construction ability and developed the waterproofing-drainage system which is able to solve the water leakage problem fundamentally by analyzing precedented 2-arch tunnels and investigating their sites in and out of nation. We also determined fixed quantity of support by a large-scale model test and numerical analysis. We want to contribute to 2-arch tunnel design hereafter introducing design procedure and method applied here.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.970-979
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• 2006

Construction of underground structure requires higher standard of planning and design specifications than in surface construction. However, high construction cost and difficult working environment limit design level and construction quality. One of the most sensitive factors to be considered are infiltration and external pore-water pressures. Development of pore-water pressure may accelerate leakage and cause deterioration of the lining. In this paper, the development of pore-water pressure and its potential effect on the linings are investigated using physical model tests. A simple physical equipment model with well-defined hydraulic boundary conditions was devised. The deterioration procedure was simulated by controlling both the permeability of filters and flowrate. Development of pore-water pressure was monitored on the lining using pore pressure measurement cells. Test results identified the mechanim of pore-water pressure development on the tunnel lining which is the effect of deterioration of drainage system. The laboratory tests were simulated using coupled numerical method, and shown that the deterioration mechanism can be reproduced using coupled numerical modelling method.

• Advances in pediatric surgery
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• v.17 no.1
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• pp.51-57
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• 2011

Use of laparoscopic appendectomy (LA) for perforated appendicitis (PA) in children remains controversial because of the development of postoperative intra-abdominal abscess formation. We developed the irrigation method for the prevention of abscess formation after LA performed for PA in children with severe panperitonitis. We called it 'the shaking irrigation'. The object of this study was to analyze the efficacy of this irrigation method. All cases of PA with severe panperitonitis in children that underwent LA with massive shaking irrigation and drainage between June 2003 and December 2007 were studied retrospectively. We included only PA with panperitonitis and large amounts of purulent ascites throughout the abdomen as well as an inflamed small bowel with ileus. Thirty-four children were involved in this study. The mean patient age was eight years. The mean amount of irrigation fluid was 8.2 L (range: 4-15 L), The mean operative time was 89.5 min. The mean length of the hospital stay was 5.1 days. There were no postoperative intra-abdominal abscesses. There was no conversion to open surgery. In conclusion, Use of LA in PA with severe panperitonitis in children is safe and effective. Massive shaking irrigation and abdominal drainage appears to prevent intra-abdominal abscesses after LA for PA with panperitonitis.

• Water for future
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• v.14 no.4
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• pp.27-34
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• 1981

The design flow of the urban strom drainage systems has been assessed largely on a basis of empirical relations between rainfall and runoff, and the rational formula has been widely used for the cities in our country. In order to estimate it more accurately, the urban runoff simulation model based on the RRl method has been developed and applied to the sample basin in this study. The rainfall hyetograph of the design stromfor the design flow has been obtained by the determination of the total rainfall and the temporal distributions of that rainfall. The total rainfall has been assessed from the empirical formula of rainfall intensity and the temporal distribution of that rainfall determined on the basis of Huff's method from the historical rainfall data of the basin. The virtual inflow hydrograph to each inlet of the basin has been constructed by computing the series of discharges in each time increment, using design strom hyetograph and time-area diagram. The actual runoff hydrograph at the basin outlet has been computed from the virtual inflow hydrographs by developing a relations between discharge and storage for the watershed. The discharge data for verification of the simulated runoff hydrograph are not available in the sample basin and so the sensitivity analysis of the simulation model has not been possible. The peak discharge for the design of drainage systems has been estimated from the computed runoff hydrograph at the basin outlet and compared to thatl obtained form the rational formula.