• Journal of Korea Water Resources Association
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• v.43 no.11
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• pp.967-976
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• 2010

AFDA (Approximate Full Distribution Approach) model of FORM (First-Order Reliability Model) which can quantitatively calculate the probability that storm sewer reach to performance limit state was developed in this study. It was defined as a failure if amount of inflow exceed the capacity of storm sewer. Manning's equation and rational equation were used to determine the capacity and inflow of reliability function. Furthermore, statistical characteristics and distribution for the random variables were analyzed as a reliability analysis. It was found that the statistical distribution for annual maximum rainfall intensity of 10 cities in Korea is matched well with Gumbel distribution. Reliability model developed in this study was applied to Y shaped storm sewer system to calculate the probability that storm sewer may exceed the performance limit state. Probability of failure according to diameter was calculated using Manning's equation. Especially, probability of failure of storm sewer in Mungyeong and Daejeon was calculated using rainfall intensity of 50-year return period. It was found that probability of failure can be significantly increased if diameter is decreased below the original diameter. Therefore, cleaning the debris in sewer pipes to maintain the original pipe diameter should be one of the best ways to reduce the probability of failure of storm sewer. In sewer system, two sewer pipes can flow into one sewer pipe. For this case, probability of system failure was calculated using multiple failure mode. Reliability model developed in this study can be applied to design, maintenance, management, and control of storm sewer system.

• Journal of Korean Society for Geospatial Information Science
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• v.6 no.2 s.12
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• pp.69-79
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• 1998

It is one of the most crutial thing to secure efficient infrastructure of social infrastructure Including rna drinking water, sewer, gas, and electricity, etc. in modern society. Among them, the sourer system need to be properly maintained so as to sustain water quality over the large watershed thereby to provide reasonable level of living environment A few municipalities and private firms have so in been using sewer management system for assessing existing sewer network and auxiliary facilities. Such existing system can only provide functions to manage the sewer pipe itself and they can not fully estimate the amount of sewage water over the pipe through 4he network analysis due to the deficiency of the system Such a limited sewer network analysis function can only analyze the whole network under the assumption of uniformity. The results from such a process can not be fully implemented in the field. Therefore, this study emphasized the development of a sewer management system which can provide practical values from network analysts considering areal peculiarities using a zoning map utilizing a GIS. The system can support analyzing scenarios due to the changes of sewer amounts from the changes of population densities and rainfall amounts not to mention of calculating sewer amount for individual sewer pipes. furthermore, the system can support the decision making for better designing sewer facilities from the expansion of metropolitan areas and constructing satellite cities. Eventually, it will contribute to enhance the effectiveness of sewer-related works and services for residents as well as supporting a decision making for minor and major trouble-shootings.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.72-77
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• 2018

In this study, cutting robot system which could cut lateral protrusion into main pipes at the connection of sewer pipes was developed. In addition, the cutting test of the robot for the lateral protrusions were performed. The test parameters included materials used in the main pipes and diameters of the pipes, and materials used in the protruded pipes. The materials type of the main pipes were concrete and PE, and the diameters of the pipes were 300 and 500 mm. The materials type used in the protruded pipes were PE and PVC, and the diameter of the pipes was 100 mm. Remaining length of each lateral protruded pipe was less than 5 mm which was an target value of cutting performance. It showd that test results were within the target value. Therefore, in the repair of sewer pipes, the lateral protruded pipes can be cut by using the robot system developed in this paper.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.6
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• pp.749-757
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• 2005

The present study analyzed actual cases of designed flow estimation method and designed flow rate of sewage pipe lines. In order to examine the effects of peak-hour demand factor estimation with given daily highest peak loading, we analyzed its effects on designed flow rate with changing the peak-hour demand factor from 2.0 to 10.0. The results of this study are as follows. When reviewing the recent designs, we found that 59.4% of pipe line with 250mm and 300mm diameter, which fall under minimum allowable pipeline did not meet the minimum velocity which is specified as 0.6m/sec in design standards. The pipe line that have minimal access population or have very low slope did not satisfy the minimum velocity. In estimating the designed sewage flow, the applied daily highest peak loading and hourly highest peaking loading were the load factor for the entire population of the planned area, and for the peak loading of the initial pipes connected to a very small population, we applied the same factor as that applied to the entire area and, as a result, the hourly highest flow was underestimated. Because, in case of the initial pipes, the method of applying the same peak loading to all subject areas is highly possible to produce underestimated design flow, when estimating the designed flow of the initial pipes connected to a small population need to adopt a rational flow factor according to the size of population. For this, it is considered to investigate and analyze raw data on daily and hourly variation of sewage flow.

• Journal of the Korean GEO-environmental Society
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• v.16 no.12
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• pp.13-22
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• 2015

Developed ground cavity due to leakage of decrepit old sewer pipe causes ground surface settlement and brittle fracture of pavement. Recently, for 5 years, frequency of occurrence of ground subsidence phenomenon tends to increase rapidly and/or steadily. It is difficult to investigate ground surface settlement and/or subsidence in urban area because most ground surfaces are covered with asphalt or concrete pavement. In this research, therefore, ground surface settlement, influence zone and settlement of sewer pipe were analyzed using finite element method. Not only reinforced effect of pseudo-plastic backfill that is applied to prevent ground surface settlement or subsidence spot, was compared and analyzed using numerical analysis program, but also direct shear test was carried out to determine strength parameters of pseudo-plastic backfill.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.5
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• pp.631-639
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• 2007

This study investigated the construction and operation status of sewer pipes and water-purifier tanks near densely populated areas like large apartment complexes, in order to find out cause for offensive orders. The study results revealed that the main cause arose from the water-purifier tank and public sewer pipes near ordinary residential areas. First, in case of independent water-purifier tanks, the air is forced into the rotten part of large tanks nearby which should be operated in an anaerobic state, so that the tank changes into an aerobic state, or dirty water, which is returned during the sludge return process, falls on the top of the rotten tank, preventing scum from forming within the tank. Such problems cause incompletely purified water in the purifier tank to be discharged, which in turn results in filthy water. Second, in case of public sewer pipes, deteriorated or aging pipes, or the mixture of rain water and dirty water by mixing up combined and separated sewers system can cause foul odors in residential areas. Therefore, offensive odors in residential areas can be radically reduced through the appropriate construction and management of facilities including water-purifier tanks. As well, if more separate sewers are installed as part of an improvement project for public sewer pipes, complaints about foul smell can be minimized.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.485-489
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• 2008

To achieve the optimal sewer layout design, most developed models are designed to determine pipe diameter, slope and overall layout in order to minimize the least cost for the design rainfall. However, these models are not capable of considering the superposition effect of runoff hydrographs entering each junction. The suggested Optimal Sewer Layout Model (OSLM) is designed to control flows and distribute the node inflows while taking into consideration the superposition effect for reducing the inundation risk from the sewer pipes. The suggested model used the genetic algorithm to determine the optimal layout, which was connected to the SWMM (Storm Water Management Model) for the calculation of the hydraulic analysis. The suggested model was applied to an urban watershed of 35 ha, which is located in Seoul, Korea. By using the suggested model, several rainfall events, including the design rainfall and excessive rainfalls, were used to generate runoff hydrographs from a modified sewer layout. By the results, the peak outflows at the outlet were decreased and the overflows were also reduced.

• Journal of Korea Water Resources Association
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• v.39 no.6 s.167
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• pp.533-544
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• 2006

The deposition of solids in combined sewer systems results in a loss of flow capacity that may restrict flow and cause a local flooding and enhanced solids deposition. In order to solve these problems and proper pipe management, estimation of solid loads from sewer and surface in a drainage basin is needed but this task is very difficult and extremely expensive. In this study, generalized procedures for estimating sewer solid loads during dry weather in combined sewer systems and for estimating solid loads on surface in a drainage basin developed by the U. S. Environmental Protection Agency were applied and analyzed in Gunja drainage basin in Korea. As result, the estimated solid loads from sewer and surface are 205.8,759kg/yr and 1,321,993kg/yr respectively, and total solid loads is 1,527,752kg/yr. The estimated solid removal from street cleaning, dredging from pipe system and pumping house is 1,486,636kg/yr. Therefore, the applied methods show resonable results. More reliable estimation can be achieved if long-term measurements and adjustment of estimation equations are carried out, and this estimation methods can be used usefully for the management of combined sewer system with reduction of cost and effort.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4977-4983
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• 2015

The full depth excavation induces couple of technical and social problems like increase of construction cost and time for excavation and backfill, increase of public complains and delay of traffic, and so force. In order to overcome these problems, lots of laboratory tests were carried out for sewer pipeline of maintenance materials with trenchless methods. The testing materials are PVC strip and then the lab tests were followed by Korean Standard. We will treat the structure safety and pipe integrity of PVC profile more excellent than the profile have application to SPR. There is no side-effect to process and to satisfy the criteria of tensile strength, impact strength and softening temperature. The profile with resin adhesive showed no leakage of water at specific pressure.

• Journal of the Korean Geotechnical Society
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• v.32 no.12
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• pp.33-43
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• 2016

In order to analyze ground relaxation and cavity formation mechanism due to deteriorated sewer pipe, field test was carried out and a numerical assessments were compared with the field test results. An artificial underground cavity was intended using the ice block overlaying the buried pipe and confirmed that the cavity and relaxation of the surrounding ground were gradually formed as the ice block starts to melt down. Such mechanism was highly suspected to be involved with soil particle interlocking as a soil compaction was a typical process for the buried pipes. In exploring such mechanism numerically, commercially available DEM (Discrete Element Method) code PFC2D was used and the interlocking induced cavern behaviors were successfully simulated and compared with field test results by utilizing the clump logic imbedded in PFC code.