• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.780-785
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• 2005

Vibration has been severly increased at the branch pipe of main steam header since the commercial operation of a nuclear power plant. Intense broad band disturbance flow at the discontinuous region such as elbow, valve or heather generates the acoustical pulsation which is propagated through the piping system. The pulsation becomes the source of low frequency vibration at piping system. If it coincide with natural frequency of the pipe system, excessive vibration is made. High level vibration due to the pressure pulsation related to high dynamic stress, and ultimately, to failure probability affects fatally the reliability and confidence of plant piping system. This paper discusses vibration effect for the branch pipe system due to acoustical pulsations by broad band disturbance flow at the large main steam header in 7nn nuclear power plant. The exciting sources and response or the piping system are investigated by using on site measurements and analytical approaches. It is identified that excessive vibration is caused by acoustical pulsations of 1.3Hz, 4.4Hz and 6.6Hz transferred from main steam header, which are coincided with fundamental natural frequencies of the piping structure. The energy absorbing restraints with additional stiffness were installed to reduce excessive vibration.

• Nuclear Engineering and Technology
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• v.53 no.3
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• pp.1004-1012
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• 2021

High density polyethylene (HDPE) pipe has many advantages over metallic pipe, and has been used in non-safety related application for years in some nuclear power plants (NPPs). Recently, HDPE pipe was introduced into safety related applications. The main difference between safety-related and non-safety-related pipes in NPPs is the design method of extra loadings such as gravity, temperature, and earthquake. In this paper, the mechanical behavior of HDPE pipe under various loads in pipe gallery was studied by finite element analysis (FEA). Stress concentrations were found at the fusion regions on inner surface of mitered elbows of HDPE pipe system. The effects of various factors were analyzed, and the influence of various loads on the damage of HDPE pipe system were evaluated. The results of this paper provide a reference for the design of nuclear safety-related Class 3 HDPE pipe. In addition, as the HDPE pipes analyzed in this paper were suspended in pipe gallery, it can also serve as a supplementary reference for current ASME standard on Class 3 HDPE pipe, which only covers the application for buried pipe application.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.897-902
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• 2001

This paper describes the evaluation of noise influence for residental and boundary areas in 75MW thermal power plant. It includes the measurements of noise level around the boundary area of the plant, identification of noise propagating path, and discussion on the measures. Noise assessments are carried out based on the ISO 3744, ISO 9613-1 and ISO 9613-2 to predict the noise distribution of specific locations from the noise sources such as power transformers, flash vent-pipe, I.D.fan, and stack. It is identified the vent-pipe of flash tank in thermal power plant as the root cause of the environmental noise during the plant commissioning process.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.19 no.2
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• pp.146-154
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• 2023

In nuclear power plants, ultrasonic test for pipe wall thickness measurement is used during periodic inspections to prevent pipe rupture due to pipe wall thinning. However, when measuring pipe wall thickness using ultrasonic test, a significant amount of measurement error occurs due to the on-site conditions of the nuclear power plant. If the maximum pipe wall thinning rate is decided by the measured pipe wall thickness containing a significant error, the pipe wall thinning rate data have significant uncertainty and systematic overestimation. This study proposes preprocessing of pipe wall thinning measurement data using support vector machine regression algorithm. By using support vector machine, pipe wall thinning measurement data can be smoothened and accordingly uncertainty and systematic overestimation of the estimated pipe wall thinning rate data can be reduced.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.1
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• pp.37-44
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• 2012

This paper describes energy loss in a pipe line of refuse collecting system. Analysis of energy loss in a pipe line is the decisive factor in a design of refuse collecting system. Using the results of energy loss analysis, we can determine the power of turbo-blower. The flow characteristics of the pipe line with refuse bags were analyzed by three-dimensional CFD. The refuse bag is modeled by using the shape obtained from profile measurement. Friction factors were calculated with changing the refuse bag size, mixing ratio and Reynolds number. And drag coefficients were calculated using the CFD results. From the results we can calculate energy loss in a pipe line of refuse collecting system and predict the capacity of turbo-blower.

• Journal of Welding and Joining
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• v.32 no.2
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• pp.4-8
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• 2014

In this research, GTA overlay welding system is developed for inside of straight pipes in various diameter. It can be applied to oil, ship building and plant industry, especially pipes connected to pressure vessels, for the purpose of cost reduction by cladding inside of pipes with corrosion and heat resistant alloys such as stainless steel or Inconel. Developed system consists of GTA power source, torch, wire feeding system, automatic arc length adjusting device, CCD camera and cooling unit. Two types of pipe inside overlay welding system are developed. One is for maximum 3m pipe length with 3 inch ~ 12 inch pipe outer diameter. Another type can be applied to maximum 12m pipe length with 7 ~ 24 inch OD. Developed system successfully produced inside cladded pipe and the results are shown through cross sectional images of the pipes.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.18 no.1
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• pp.11-18
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• 2022

When wall-thinning in a pipe occurs during operation of nuclear power plant, reinforcement of the pipe needs to be performed. Accordingly, the structural response of the piping system due to introduction of the reinforcement may be re-evaluated. For elastic structural analysis of the piping system with the reinforced pipe using finite element (FE) analysis, the stiffness of the reinforced pipe is needed. In this study, the stiffness matrix of wall-thinned pipe with pad reinforcement or composite reinforcement is analytically derived. The validity of the proposed equations is checked by comparing with systematic finite element (FE) analysis results.

• Nuclear Engineering and Technology
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• v.48 no.3
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• pp.820-830
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• 2016

Pipe wall thinning by flow-accelerated corrosion and various types of erosion is a significant and costly damage phenomenon in secondary piping systems of nuclear power plants (NPPs). Most NPPs have management programs to ensure pipe integrity due to wall thinning that includes periodic measurements for pipe wall thicknesses using nondestructive evaluation techniques. Numerous measurements using ultrasonic tests (UTs; one of the nondestructive evaluation technologies) have been performed during scheduled outages in NPPs. Using the thickness measurement data, wall thinning rates of each component are determined conservatively according to several evaluation methods developed by the United States Electric Power Research Institute. However, little is known about the conservativeness or reliability of the evaluation methods because of a lack of understanding of the measurement error. In this study, quantitative models for UT thickness measurement deviations of nuclear pipes and fittings were developed as the first step for establishing an optimized thinning evaluation procedure considering measurement error. In order to understand the characteristics of UT thickness measurement errors of nuclear pipes and fittings, round robin test results, which were obtained by previous researchers under laboratory conditions, were analyzed. Then, based on a large dataset of actual plant data from four NPPs, a quantitative model for UT thickness measurement deviation is proposed for plant conditions.

• Journal of Plant Biology
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• v.20 no.2
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• pp.103-107
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• 1977

Two sample varieties of Yushin and Jinheung were used for the experiment in low-level wetty paddy field which was arranged with PVC pipe underdrainage of 6m in distance and 60cm, 90cm, and 120cm in depth and control, using sprit plot design with three replications. On the yield of brown rice, Yushin was increased by 24.8% in the 90cm plot and Jinheung by 16.7% in the 120cm plot, respectively, over the control. The ratio of matured grains of these two varieties was increased significantly by the underdrainage and the number of grains per head of Yushin was also increased in drained plots. Otherwise, the underdrainage enhanced the plant height in the early growth of rice plant and further increased the culm height and panicle length. It seemed that these results might enhance the light-receiving effciency in the latter growth of rice plant and bring about the effect fo increased yields by the underdrainage.

• Special Issue of the Society of Naval Architects of Korea
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• 2005.06a
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• pp.127-133
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• 2005

DSME has successfully developed the unified CAD system (DACOS) for the commercial ship based on its design know-how accumulated for several years. Currently, DSME is expanding the unified CAD system to plant and special ship design. In this paper, the development of pipe design, especially, isometric drawing and BOM(Bill of Material) generation will be introduced isometric drawing and BOM generation are major activities of pipe design in shipbuilding. The drawing is used for pipe construction and installation while the BOM is used for purchasing and manufacturing pipe line. These activities are time-consuming and tedious jobs done by designers because the drawing should be generated as a non-scaled symbolized drawing that can be easily understood and the BOM information should be extracted without mistake. Therefore, we implemented automatic isometric drawing and 80M generation system for pipe design. In this paper, the developed system and the used technology will as well be introduced and a design output in a plant project as an applied example will be illustrated.