• Journal of Energy Engineering
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• v.23 no.3
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• pp.116-124
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• 2014

In the plants operated under high temperature condition, piping system load analysis is often performed to prevent accidents caused by thermal deformation and also to locate inspection prioritity points of the piping system. In this study, piping system stress analysis was performed for a pipe system between the reactors in a process plant. The piping system includes typically installed hangers and expansion joints. In order to evaluate the effects of structural components such as hangers and expansion joints, the case for the expansion joint or the hanger under abnormal operation is considered. By comparison anlaysis results of piping system during normal operation and abnormal operation, the role of each pipe components are studied.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.1
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• pp.19-24
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• 2021

This paper presents a method to generate three-dimensional AR/VR models using the information in Isogen data files (IDFs). An IDF is an output file produced by ISOGEN that contains piping isometric drawings. A piping isometric drawing is used for pipeline installation in the shipyard; therefore, the drawing describes assembly information with symbolic features, not with detailed geometric features. An IDF specifies relationships between piping routes and components with three-dimensional points and tag information as well as the bill of the materials of a pipeline. The key idea of this paper is that AR/VR models can be generated with the piping route points data and piping components tag information in real time, without any conversion of standard data exchange file formats, such as STP, IGES, and SAT. This paper describes IDF data structure and suggests the geometry generation process with IDF data and parametric functions.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.12 no.1
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• pp.141-148
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• 2016

This paper presents an overview of worldwide electric power development and National $700^{\circ}C$ Hyper Supercritical coal-fired power generation(HSC) focus on materials and manufacturing process. To Increase the efficiency of electric power generation, It is necessary to increase steam temperature and pressure. In that case, New material and manufacturing process shall be developed for boiler and turbine component in high temperature and pressure operating condition. Therefore, Much Efforts in worldwide are progressing to develop materials and manufacturing technology and to build and operate an HSC.

• Journal of the Korean Institute of Gas
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• v.16 no.1
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• pp.22-25
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• 2012

Welding and/or fusion in polyethylene(PE) system made on site is focused on the control of the welding or fusion process to follow proper procedure. The process control is important, but it is not sufficient for the long term reliability of a pipe system. To achieve the rate of failure close to zero, Non Destructive Testing(NDT) is necessary in addition to joining process control. For electrofusion joints several non-destructive testing methods are available. The ultrasonic phased array technique is possible to detect various defects including wire deviations and regions with lack of fusion. In this studies, testing was carried to detect the defect after electrofusion joining of polyethylene piping is utilized by the ultrasonic phased array technique. From testing data, ultrasonic phased array technique is recommended as a reliable non-destructive testing method.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.60-70
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• 2020

The outfitting design of ships and offshore structures is mainly undertaken in a restricted space. Pipes occupying a large portion of outfitting design are normally manufactured outside the shipyard. This complicated manufacturing process results in frequent delivery delays. Inevitable design modifications and material changes have also resulted in inefficient pipe installation works. In this study, an algorithm is proposed to systematically determine the pipe installation sequence. An accurate and fast algorithm to identify the geometric relationship of piping materials is presented. To improve the calculation efficiency, the interference is gradually examined from simplified to complicated shapes. It is demonstrated that the calculation efficiency is significantly improved with successive geometric operations such as back-face culling and use of bounding boxes. After the final installation sequence is determined, the entire installation process is visualized in a virtual reality environment so that the process can be rendered and understood for a full-scale model.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.10 no.1
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• pp.1-6
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• 2014

PID(Proportional, Integral, Derivative) controller is one of the most used process controllers in nuclear power plants. The optimized parameter setting of process controller contributes to the stable operation and efficiency in the operating nuclear power plants. PID parameter setting is tuned when new process control system is established or process control system is changed. It is a burdensome work for I&C(Instrument and Control) engineers to tune the PID controller because it requires a lot of experience and knowledge. When the plant is in operation, inadequate PID parameter setting can be the cause of the unstable process of the plant. Therefore the results of PID parameter setting should be compared, simulated, verified and finally optimized. The practical PID tuning methods used in process controller are tuning operation calculation(Ziegler-Nicholes, Minimum TIAE, Lambda, IMC), exclusive tuning program based on computer and Matlab application. This paper introduces the various tuning methods and suggests an optimized PID tuning process in the operating nuclear power plants.

• Journal of the Korean Society of Safety
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• v.10 no.2
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• pp.3-9
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• 1995

Several piping material test methods have been developed as a result of advances in elastic-plastic fracture mechanics. It's known that, crack propagation of the materials strongly governed by the $J_{Ic}$ value. But the value is still difficult to be obtained because of it's complicate and troble-some determination process. In this paper, to prove the validity of the developed test procedure a series of tests were peformed at various temperatures and for different material directions. directions.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.11 no.1
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• pp.69-73
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• 2015

The study investigated effects of residual stresses and Charpy impact energy on brittle fractures of the butt weld between the valve and the piping, and of the valve body in nuclear power plants via a linear elastic fracture mechanics approach in the ASME B&PV Code, Sec.XI and finite element analysis. Weld residual stress in a butt weld between close check valve and piping, and residual stress in the valve due to casting process were assumed to be proportional to yield strength of base metal. Operating stresses in the butt weld and the valve body were calculated using approximate engineering formulae and finite element analysis, respectively. Applied stress intensity factors were calculated by assuming postulated cracks with specific sizes and then by substituting the residual stresses and the operating stresses into engineering formulae presented in the ASME B&PV Code, Sec.III. Plane strain fracture toughness was derived by using a correlation between Charpy V-notch impact energy and fracture toughness. Structural integrity of the weld and the body against brittle fracture was assessed by using the applied stress intensity factors, plane strain fracture toughness and the linear elastic fracture mechanics approach. As a result, it was identified that the structural integrity was maintained with decreasing the residual stress levels and increasing the Charpy V-notch impact energy.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.3
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• pp.381-389
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• 2001

The objective of this paper is to evaluate the fracture resistance characteristics of SA508 Cl.1a to SA508 Cl.3 welds manufactured for the reactor coolant loop piping system of nuclear power plants. The effect of the crack plane orientation to the welding process orientation and the preheat temperature on the fracture resistance characteristics were discussed. Results of the fracture resistance test showed that the effect of the crack plane orientation to the welding process orientation of the fracture toughness is significant, while that of preheat temperature on the fracture toughness is negligible. The micro Vickers hardness test, the metallographic observation and the fractography analysis were conducted to analyse the crack jump phenomenon on the L-R crack plane orientation in the multi-pass welding zone. As these results, it is shown that the crack jump phenomenon was produced because of the inhomogeneity between welding beads and the crack plane orientation must be considered for the safety of the welding zone in the piping system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1990.10a
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• pp.113-124
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• 1990

Tap lines are small branch piping generally less than two inches in diameter. They typically branch off of header piping having a much larger diameter. An example of a common tap line is a 3/4 inch size high point vent or low point drain. Most tap lines have at least one valve near the header tap connection to provide isolation. Two valves are often required for double isolation. A light water reactor(LWR) nuclear power plant will have several hundred tap lines. These lines come in many sizes and shapes and serve numerous functions. A single process piping valve may have three different tap lines associated with it (figure 1). Table 1 delineates the different categories of tap lines. Vibration failures of tap lines are a common occurrence in all industrial plants including nuclear and fossil power plants. These types of failures constitute a significant percentage of all piping related failures. An unscheduled plant shutdown or outage resulting from the failure of a tap line decreases plant reliability and may have a detrimental effect on plant safety. Most tap line vibration failures can be avoided through the use of appropriate routing and support techniques. Standardized designs can be developed for use in a myriad of applications. These designs will not only minimize failures but will also reduce the necessary analysis and installation efforts.