• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.6
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• pp.462-470
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• 2016

The locking load of a conventional manhole depends on the weight of its cover. Locking-type manhole structures with a special locking mechanism were recently developed to prevent accidents such as stolen cover, away cover from a frame. The weight of the manhole structure can be reduced under structural safety because the locking force of a locking-type manhole is greater than the weight of the cover. A light-weight manhole cover is developed in this study by using a finite element stress analysis and the design of experiments. Static stress analysis and fracture experiments are also conducted to analyze the states of the initial product. The optimum light-weight manhole cover considering manufacturing molds is developed and tested. Consequently, the weight was found to reduce by 16%. In addition, the fracture load increased by 38%.

• Journal of Welding and Joining
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• v.32 no.2
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• pp.54-62
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• 2014

Manhole cover, which is usually made of grey cast iron and consists of frame and cover, should have enough strength to support the heavy traffic load. The manhole cover made of cast iron has heavy weight to handle manually and is vulnerable to impact force with its brittle characteristics. Moreover, its production process of casting has been regulated in terms of environmental pollution. In this study, steel manhole cover is proposed to substitute the cast cover with a series of structural analyses to confirm its strength to support the test load for manhole cover. The cover of the proposed steel manhole cover is made of thin circular pate and stiffeners below the plate. Rectangular columns and hollow circular plate were selected for the shape of the stiffener. In order to give enough strength for the cover to behave within elastic range in the loading, strengthening structures of the cover were varied with increasing the number and the size of the stiffeners. The results of the analyses revealed that when both the hollow circular stiffener and cross stiffeners were additionally applied at the same time to the steel cover with longitudinal stiffeners, the maximum stress level in the cover could be reduced to that level presented in the cast cover.

• Archives of design research
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• v.19 no.3 s.65
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• pp.167-182
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• 2006

From 1998 Seoul city is being rebuilt for 'the city which people want to go around on foot'. Many streets only for cars have been transformed for pedestrians. In addition to that streets are built not only just to pass by, but also enjoy themselves, so 8 Streets in Seoul have been redecorated as 'Streets of History and Culture'. These Streets are chosen because they have their own unique history or culture, so they are remodeled with lightings, exhibition pavilions or sign postings etc except manhole covers. Even these 8 streets have manhole covers; they are not particular, just same as like other streets. For most streets manhole cover is an essential component of them, but it is mostly omitted to be designed in particular. For the most time some of the standard manhole covers are installed in a street. Taking a look at manholes in Minneapolis city, they inform visitors what the landmark, landscape, symbol, representative flower or tree of the city is. Sometimes they are designed by famous artists and become art which all pedestrian can enjoy. If manhole covers in 'the streets of history and culture' are designed to represent its history or culture, visitors will get information about there easily and enjoy their design. To foster manhole cover designs, the government office should co-work with professional designers or design societies and encourage people to spend a certain amount of the construction cost to design manhole covers. At school designing manhole cover can be handled in an art class and besides can have a class in the field, streets to observe manhole cover designs. Getting more concern of manhole cover design, competitions and exhibitions are able to be held.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.10
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• pp.5095-5111
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• 2019

A multi-rotor Unmanned Aerial Vehicle (UAV) system is developed to solve the manhole cover detection problem for the infrastructure maintenance in the suburbs of big city. The visible light sensor is employed to collect the ground image data and a series of image processing and machine learning methods are used to detect the manhole cover. First, the image enhancement technique is employed to improve the imaging effect of visible light camera. An imaging environment perception method is used to increase the computation robustness: the blind Image Quality Evaluation Metrics (IQEMs) are used to percept the imaging environment and select the images which have a high imaging definition for the following computation. Because of its excellent processing effect the adaptive Multiple Scale Retinex (MSR) is used to enhance the imaging quality. Second, the Single Shot multi-box Detector (SSD) method is utilized to identify the manhole cover for its stable processing effect. Third, the spatial coordinate of manhole cover is also estimated from the ground image. The practical applications have verified the outdoor environment adaptability of proposed algorithm and the target detection correctness of proposed system. The detection accuracy can reach 99% and the positioning accuracy is about 0.7 meters.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.581-586
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• 2018

Cast iron manhole lids cause environmental pollution during the manufacturing process, and the work environment is very poor. In addition, if the height of the manhole cover does not match the height of the road surface, it causes considerable inconvenience and safety problems. This study proposes a height - adjustable steel manhole cover that can replace cast iron manhole covers and easily match the road surface with the upper surface of the manhole cover. Structural analysis was performed to grasp the design variable of the structure of the manhole cover, satisfying the required quality performance. To fabricate a manhole cover that satisfies the required load capacity, the optimal design for the U-shaped reinforcement structure was made. The cylindrical shape of the height adjustment part and the low frame were formed by bending the steel sheet into a circular shape and then welding. Reinforcing bars were also made by bending a steel plate. The height adjustment groove was machined by a CNC milling machine. Four prototypes were fabricated and a load bearing test was carried out, and new manhole cover was made reflecting results of the test. In the load bearing test, there was no breakage of the welded part, and deformation occurred mainly at the contact area between the groove and gusset plate. Deformation of 1 to 2.7mm occurred due to a load of 450kN. On the other hand, after removing the load, there was almost no residual deformation, and the load bearing evaluation was judged to be satisfactory because the manhole cover could be disassembled and reassembled.

• Journal of Korea Society of Digital Industry and Information Management
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• v.13 no.2
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• pp.53-61
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• 2017

How to manage manhole is to estimate the part without observation and maintain the sewer. To get the information about current flow rate, visiting and measuring specific manhole is positively necessary. Also, there are some problems that accurate measurement of flow rate is difficult and obtaining the information about real-time whole flow rate is impossible. This thesis will easily grasp the accurate location and type of manhole to solve the problems, and provide the manhole system conveying information through direct radio communication with a manhole cover to renewal information of manhole properly. Besides, it intends to save the information about management of waterworks, maintenance of facilities, data for flow rate, and structure of manhole. Using these, it is supposed to offer how to handle manhole. Thus, this thesis delivers the information to manhole and into central servers directly without wire and provides the system and management method for effective maintenance of manhole.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.648-654
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• 2018

In order to maintain manholes installed on the road, the manhole should be easy to open and close. Manhole covers under harsh conditions require that they can be lifted when attempting to open the manhole because the frame and cover are stuck and difficult to open and close. In this study, the design of a lifting mechanism was carried out to improve and integrate the locking type manhole. The mechanism of the locking manhole is that when the bolt located at the center is turned, the hub connected with the bolt descends, and the hook connected to the hub is rotated. The end of the hook is hooked to the manhole frame. The auxiliary device was installed on the hook so that the manhole cover can be lifted. The structure was designed to endure about 300kg of lifting force based on 70% of the yield stress of the hook to perform lifting function. The shape design was performed through the structural analysis using the finite element method. First, the basic design was performed with the simplified 2-dimensional model and the attachment position and shape were designed through the 3-dimensional model. In order to find out the structural problems of the designed shape, the scale downed model was fabricated through 3D printing and confirmed that the lifting function worked. Finally, it was confirmed that both the locking and the average lifting of about 6.1 mm can be done by applying the lifting mechanism through the machining and applying it to the existing locking manhole.

• Journal of the Korean Society of Industry Convergence
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• v.7 no.1
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• pp.63-68
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• 2004

There are a lot of manholes such as for water supply, sewage, telecommunication cable, traffic sign, electricity supply, and rainwater, etc. Conventional manholes installed on a road are impossible to adjust height, so that they should be entirely excavated to reinstall or repair. This entire excavation of a manhole causes too much time-consuming work, waste of resources, and obstruction of traffic. In this study, in order to solve the above mentioned problems, a cover, outer and inner parts of a manhole are integrated by gear-shaped parts located between outer and inner parts of a manhole. Mechanical design is performed to determine dimension of gear-shaped parts by Taguchi orthogonal array table. Cast molds for a gear-shaped manhole are also manufactured.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.710-715
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• 2004

There are a lot of manholes such as for water supply, sewage, telecommunication cable, traffic sign, electricity supply, and rainwater, etc. Conventional manholes installed on a road are impossible to adjust height, so that they should be entirely excavated to reinstall or repair. This entire excavation of a manhole causes too much time-consuming work, waste of resources, and obstruction of traffic. In this study, in order to solve the above mentioned problems, a cover, outer and inner parts of a manhole are integrated by gear-shaped parts located between outer and inner parts of a manhole. Mechanical design is performed to determine dimension of gear-shaped parts by Taguchi orthogonal array table. Cast molds for a gear-shaped manhole are also manufactured.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.6
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• pp.619-625
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• 2008

Urban sewer systems are designed to operate in open-channel flow regime and energy loss at square manholes is usually not significant. However, the energy loss at surcharged manholes is considered as one of the major causes of inundation in urban area. Therefore, it is necessary to analyze the head loss associated with manholes, especially in surcharged flow. Hydraulic experimental apparatus which can change the manhole inner profile(CASE I, II, III, and IV) and the invert types(CASE A, B, C) were installed for this study. The experimental discharge was $16{\ell}/sec$. As the ratio of b/D(manhole width/inflow pipe diameter) increases, head loss coefficient increases due to strong horizontal swirl motion. The head loss coefficients for CASE I, II, III, and IV were 0.46, 0.38, 0.28 and 0.37, respectively. Side covers increase considerably drainage capacity at surcharged square manhole when the ratio of d/D(side cover diameter/inflow pipe diameter) was 1.0. The head loss coefficients for CASE A, B, and C were 0.45, 0.37, and 0.30, respectively. Accordingly, U-invert is the most effective for energy loss reduction at surcharged square manhole. This head loss coefficients could be available to evaluate the urban sewer system with surcharged flow.