• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.2
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• pp.3-8
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• 2007

Nonlinear property and contact matter are analyzed about the pipe applied with internal pressure through this study. The weakest part and its safety can be examined. Maximum equivalent stress is shown at the contact surface between bolt and nut. The value of contact stress with the pressure of 12MPa is increased 1.4 times as large as that with no pressure. The maximum contact pressure is shown at the clamp corner of the external surface on pipe. The value of contact pressure with the pressure of 12MPa is increased 1.4 times as large as that with no pressure. The radial deformation with no pressure is also increased greatly at the middle part of internal surface on pipe. But this maximum deformation on pipe with the pressure of 12MPa is shown at the part far away the support of pipe. This value is increased 5.7 times as large as that value with no pressure. As contact status, the sticking occurs most at the external surface of pipe. It also tends to occur at the contact surface between bolt and nut. At the external surface of pipe, the sticking in case of the pressure of 12MPa occurs more than that in case of no pressure.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.1050-1059
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• 2010

The GFRP(Glass-Fiber Reinforced Plastic) Pipe is designed to behave safely against the external forces and to secure stability of deformation and settlements in pipe, Since it is laid under the ground. In this syudy, the evaluation for stability was carried out by performing the preliminary numerical analysis to decide the sclae effect in case of indoor model test. As a result of, strain of laying pipes is preponderantly reviewed. Numerical analysis is conducted to evaluate on the field application through the comparison concerning relations between deformation and differential settlement in the GFRP and hume pipes.

• Journal of the Korean GEO-environmental Society
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• v.12 no.9
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• pp.27-33
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• 2011

In the case of the existing method of underground pipe construction, the difficulty of the bedding compaction of pipe causes reducing the compaction efficiency and the stability of the underground facilities and conclusively damaging the structures. One of the methods to solve these problem is using the flowable fills as a backfill material. Therefore, in this study, numerical analysis of the underground pipe was performed in order to evaluate the behavior of pipe according to backfill mixtures. To estimate the deformation characteristic of the underground pipe, the displacement of the main part of the pipe, ground settlement and vertical earth pressures were measured in different backfill mixtures and maintaining the other conditions constantly. As a result of numerical analysis, using the flowable fills as the backfill material is better than using sand in reducing the ground settlement, the pipe deformation and the vertical earth pressure aspect.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.8
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• pp.1295-1302
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• 2003

In order to evaluate a failure behavior of pipe with notch-type wall thinning, the present study performed full-scale pipe tests using the 102mm, Schedule 80 pipe specimen simulated notch- and circular-type thinning defects. The pipe tests were conducted under the conditions of both monotonic and cyclic bending moment at a constant internal pressure of 10 MPa. From the results. of experiment the failure mode, load carrying capacity, deformation ability, and fatigue life of a notch-type wall thinned pipe were investigated, and they were compared with those of a circular-type wall thinned pipe. The failure mode of notched pipe was similar to that of circular-type thinned pipe under the monotonic bending load. Under the cyclic bending load, however, the mode was clearly distinguished with variation in the shape of wall thinning. The load carrying capacity of a pipe containing notch-type wall thinning was about the same or slightly lower than that of a pipe containing circular-type wall thinning when the thinning area was subjected to tensile stress, whereas it was higher than that of a pipe containing circular-type thinning defect when the thinning area was subjected to compressive stress. On the other hand, the deformation ability and fatigue life of a notch-type wall thinned pipe was lower than those of a circular-type wall thinned pipe.

• Nuclear Engineering and Technology
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• v.50 no.1
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• pp.190-202
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• 2018

Maintaining the integrity of the major equipment in nuclear power plants is critical to the safety of the structures. In particular, the soundness of the piping is a critical matter that is directly linked to the safety of nuclear power plants. Currently, the limit state of the piping design standard is plastic collapse, and the actual pipe failure is leakage due to a penetration crack. Actual pipe failure, however, cannot be applied to the analysis of seismic fragility because it is difficult to quantify. This paper proposes methods of measuring the failure strain and deformation angle, which are necessary for evaluating the quantitative failure criteria of the steel pipe elbow using an image measurement system. Furthermore, the failure strain and deformation angle, which cannot be measured using the conventional sensors, were efficiently measured using the proposed methods.

• International Journal of Highway Engineering
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• v.5 no.2 s.16
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• pp.25-35
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• 2003

During construction of circular lifeline pipe, the non-proper compaction along the pipe and the decrease of compaction efficiency are the main problems to induce the failure of underground pipe. The use of CLSM(controlled low strength materials) is one of the applications to overcome those problems. In this research, the numerical analysis by PENTAGON FEM program was carried out for 20 cases with the couple of combinations on bedding materials, backfill materials, and pipes. From the FEM analysis, the use of CLSM as backfill materials reduced the settlement of ground surface and the deformation of pipe employed. In case of the vertical deformation on the pipe, common soil backfill for flexible pipes showed 2 times for rigid pipes, but CLSM backfill case did less deformation than the soil backfill for rigid pipes. CLSM backfills for rigid pipes showed the similar results. Judging from the FEM analysis, the use of CLSM increases the structure capacity of the underground pipes.

• International Journal of Concrete Structures and Materials
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• v.18 no.3E
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• pp.161-164
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• 2006

Cellulose fiber reinforced cement(CFRC) pipe has been gradually introduced in the pipe market as a replacement of previously popular asbestos cement pipes. Since CFRC pipe is still relatively unknown in the pipe market, there are great concerns for the design and application in practice related to the time-dependent behavior of CFRC under long-term sustained loading. This paper presents an experimental investigation of the time-dependent behavior of cellulose fiber reinforced cement(CFRC) pipe. A total of six CFRC pipes were tested under various loading levels, and their vertical deformation was recorded to understand the characteristics of the time-dependent behavior. Based on the test results, a factor of safety(FS) of 1.82 is proposed, and a regression factor(R) of 1.88 is estimated for the application of CFRC pipes in practice.

• Transactions of Materials Processing
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• v.28 no.4
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• pp.175-182
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• 2019

In this study, compression process is performed on the seamless E235 pipe using the newly developed compression technology for seamless pipe. Experimental analysis on the heterogeneity of microstructures and mechanical properties of the deformed seamless pipe is conducted. As a result, the correlation between microstructures and mechanical properties are determined. The spatial distribution of effective stress and effective strain developed in the seamless pipe deformed through compression is analyzed using the finite element method (FEM) based on different inner pressure conditions. From the results of the FEM, the impact of the inner pressure on effective stress and effective strain of the seamless pipe deformed through compression can be understood theoretically.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1012-1017
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• 2010

Sewer Pipes are not being managed for twenty years after laying. So, The life span of sewer pipes is on the decrease. For solve the life span decrease of sewer pipes, correct checking of questions and measure preparation are necessary through investigation in sewer pipes. This research investigated on the state of sewer pipes in the housing and industrial sites through CCTV(closed-circuit television) and device of digitalized strain investigation. And, a result is as follows. A results of PE, PVC, GRP, CSP investigations were found of pipe-transformation state by earth pressure and external load.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.273-279
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• 1999

In this paper the stress and strain behaivor in near homogeneous isotropic matrix of metal like steel was studied roll forming of thin steel sheet for cylindrical pipe. Analytical results reveals a body which is on the area of square thickness along and perpendicular to the width of thin steel sheet is in the state of plane strain during roll forming. As a result construction of analytical method for calculating deformation load and stably deformed length along the width of strained steel sheet was established. Also loads applied during roll forming were analyzed using two typical thin steel sheet 12.3m thick steel sheet with 42.5kg /mm2 yield strength of pipe and 5.3mm thick steel sheet with 32.5kg/mm2 yield strength of pipe. Through this analysis applicability of the analytical method for deformation load during roll forming of cylindrical thin steel pipe was evaluated with a study of necessary production technology for roll forming and design technology for roll forming machine.