• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.4
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• pp.16-23
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• 2015

The industrialization and urbanization forced to increase the density of pipelines such as water supply, sewers, and gas pipelines. The materials used for the existing pipe lines are mostly composed of concretes and steels, but it is true that the development for more durable and efficient materials has been continued performed to produce long lasting pipe lines. Recently, underground pipes serve in diverse applications such as sewer lines, drain lines, water mains, gas lines, telephone and electrical conduits, culverts, oil lines, etc. In this paper, we present the result of investigation pertaining to the structural behavior of unplasticized polyvinyl chloride (PVC-U) flexible pipes buried underground. In the investigation of structural behavior such as a ring deflection, pipe stiffness, 4-point bending test, experimental and analytical studies are conducted. In addition, pipe stiffness is determined by the parallel plate loading tests and the finite element analysis. The difference between test and analysis is about 8% although there are significant variations in the mechanical properties of the pipe material. In addition, it was found by the 4-point bending test there is no problem in the connection between the pipes by coupler.

• Magazine of the Korea Institute for Structural Maintenance and Inspection
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• v.19 no.2
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• pp.39-43
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• 2015

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.433-436
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• 1999

The spiral provides the column with the ability to absorb considerable deformation prior to failure. Although this toughness is the principal gain that is achieved by the use of spiral reinforced columns, the its serviceability is limited by the fault of lap splices. The mechanical connection for the spiral bar placement is development in the study. The study contains for the experiment of the mechanical connection.

• Structural Engineering and Mechanics
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• v.86 no.6
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• pp.739-750
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• 2023

This study examines the two-level behavior of the toggle brace damper within a steel frame having a yielding pipe damper and rotational friction damper. The proposed system has two kinds of fuse for energy dissipation in two stages. In this mechanism, rotational friction damper rather than hinged connection is used in toggle brace system, connected to a pipe damper with a limited gap. In order to create a gap, bolted connection with the slotted hole is used, such that first a specific movement of the rotational friction damper solely is engaged but with an increase in movement, the yielding damper is also involved. The performance of the system is such that at the beginning of loading the rotational friction damper, as the first fuse, absorbs energy and with increasing the input load and further movement of the frame, yielding damper as the second fuse, along with rotational friction damper would dissipate the input energy. The models created by ABAQUS are subjected to cyclic and seismic loading. Considering the results obtained, the flexibility of the hybrid two-level system is more comparable to the conventional toggle brace damper. Moreover, this system sustains longer lateral displacements. The energy dissipation of these two systems is modeled in multi-story frames in SAP2000 software and their performance is analyzed using time-history analysis. According to the results, permanent relocations of the roof in the two-level system, in comparison with toggle brace damper system in 2, 5, and 8-story building frames, in average, decrease by 15, 55, and 37% respectively. This amount in a 5-story building frame under the earthquakes with one-third scale decreases by 64%.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.279-280
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• 2023

Due to the deterioration of infrastructure, the importance of maintenance is continuously increasing. Therefore, an integrated maintenance method for various facilities is required. In this study, a maintenance priority determination method for integrated maintenance of roads and pipe network facilities was developed. It is possible to analyze attribute information by using GIS data of roads and pipe networks, and shape information can be used. This information is derived as quantitative figures for determining maintenance priorities. In the future, it is expected that facility maintenance can be further advanced in connection with maintenance method and quantity information for each facility.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.5
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• pp.435-443
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• 2018

Most of aged water supply pipes have been replaced by the open cut method. However, this method has some limitations because water pipes, in many cases, are buried together with other underground facilities or are buried in the middle of high-traffic roads or in narrow alleyways where boring machines cannot be used. This research developed a pipe bursting device for small diameter pipes that enables pipe replacement without excavating the ground, by the busting of existing buried pipes followed by the traction and insertion of new pipes. As a results of examining the field applicability of the developed device, PE pipes and PVC pipes required the tractive force of 413.65~665.69 kgf and 457.43~791.35 kgf respectively, plus an additional 30 % tractive force per elbow. The proper number of bursting head was demonstrated that the connection of more than 2 heads could secure a stable bending radius of 15D. The developed device can be improved through field experiments involving various pipe types and pipe diameters, as well as presence/absence of elbow, so as to be utilized regardless of diverse variables according to the conditions of the soils surrounding existing pipes.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.6
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• pp.144-150
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• 2018

In this study, the freezing process of L-shaped pipe exposed to the outside was investigated numerically by considering the mushy zone of freezing water. From the numerical results, it was found that the flow was outwardly directed due to the influence of the L-shaped bending part in the outside exposed part of the pipe, and the ice was formed in the shape of longitudinal corrugation on the wall surface of the pipe after the bending part. It is confirmed that this phenomenon is caused by the venturi effect due to the freezing as seen in connection with the velocity distribution in the pipe. It is found that the remelting phenomenon at the end of the freezing section occur simultaneously during the process of forming the ice in the pipe section. In regard of the factors affecting freezing, it was found that the thickness of the freezing layer is increased as the exposed pipe surface temperature is decreased, and the pipe surface temperature had a significant effect on the change of the freezing layer thickness. At the same time, it was found that the freezing layer becomes relatively thin when the water inflow rate is increased. This phenomenon was caused by reducing the exposure time of freezing water due to the vigorous flow convection of the water fluid.

• The Journal of the Korea Contents Association
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• v.22 no.3
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• pp.54-61
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• 2022

Ship is a huge system including a variety of pipe arrangements. Pipes are installed according to the design layout, however the end poistion of pipes are not well matched owing to its measurement and construction errors. In this situation, the customized pipe fitting is frequently designed to connect with both pipes, the position of which are manually measured. This paper focused that these two coordinates are measured by point cloud from RGBD sensor and the relative transformation induced by positional and orientational differences is calculated by inverse kinematics in robotics theory. Therefore, the result applies for the methodology of the pipe connection design. The pipe coordinate that is estimated by the matching and the probabilistic RANSAC method will be verified by experiments. The kinematic design parameters are computationally calculated by using the minimum degree of freedom that connects both pipe coordinates.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1167-1173
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• 2010

Forming of a silencer case was studied using a virtual tryout method. First, the appropriate blank shape was determined by cutting off the undeformed part of the rectangular blank. Then drawbeads were designed such that the formation of wrinkles on the shoulders and pipe connection can be prevented. Finally, the shape bead was designed such that fracture and formation of wrinkles around the pipe connection can be avoided. The prototype of the silencer case was manufactured in accordance with the conditions of the virtual tryout process. By comparing the formability of the prototype with the results of finite element analysis, it was found that the forming of the prototype agreed well with the results of analysis.

• Journal of the Korean Society of Safety
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• v.25 no.1
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• pp.57-61
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• 2010

Formwork is a temporary structure that supports its weight and that of fresh concrete as well as construction live loads. Scaffoling is a temporary frame used to support people and material in the construction or repair of buildings and other large structures. It is usually a modular system of metal pipes, although it can be made out of other materials. Bamboo is still used in some Asian countries like China. The purpose of a working scaffold is to provide a safe place of work with safe access suitable for the work being done. In construction site, steel pipes are usually used as scaffolds. In this study, scaffolding systems which is changed according to sleeper and joist space were measured by buckling test. Buckling load of respective scaffolding system was analyzed by structural analysis program(MIDAS). Buckling load of scaffold with/without wall connection and footboard was got by test and structural analysis. According to these results，we know that scaffolding system of case 3 is suitable. Buckling load of scaffold with wall connection is higher than without wall connection. So wall connection is important in scaffoling systems. Footboard in the scaffolding systems is not effective against promotion of buckling load. Finally, the present study results will be used to design scaffolding systems safely in the construction sites.