• 한국건설관리학회논문집
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• 제5권2호
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• pp.81-89
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• 2004

Pipe joining is one of the most critical aspects of most industrial projects, but it is regarded as one of the most inefficient processes in the construction industry. The primary objective of this paper is to explore the applicability of advanced joining technology to the use of metal pipe in the construction industry. This paper begins with a review of current practices with respect to metal joining in the construction industry. The current status of pipe joining is examined. Needs for, and benefits of, advanced joining technology are identified, and a tool for evaluating the applicability of various methods to construction is presented. Joining technologies, including mechanical joining, adhesive bonding, welding, and welding automation, are then introduced, and their applicability to the construction industry is assessed by means of this evaluation tool. It is concluded that there is significant benefits for improvement of piping process in the construction industry through the use of advanced joining technologies.

• Nuclear Engineering and Technology
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• 제54권2호
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• pp.732-740
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• 2022

A piping system stress analysis need to be re-performed for structural integrity assessment after reinforcement of a pipe with significant wall thinning. For efficient stress analysis, a one-dimensional beam element for the wall-thinned pipe with reinforcement needs to be developed. To develop the beam element, this work presents analytical equations for elastic stiffness of the wall-thinned pipe with reinforcement are analytically derived for axial tension, bending and torsion. Comparison with finite element (FE) analysis results using detailed three-dimensional solid models for wall-thinned pipe with reinforcement shows good agreement. Implementation of the proposed solutions into commercial FE programs is explained.

• 한국방재학회 논문집
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• 제8권4호
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• pp.61-66
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• 2008

상수관망의 노후화에 따른 잦은 파괴로 인해 보다 효율적인 상수관망 모니터링시스템 구축이 중요한 문제가 되었다. 상수관망의 모니터링 시스템의 하나인 "Smart-Pipe 시스템"은 영구적이며 포괄적인 자동화된 형태의 SIM 시스템으로 기존의 모니터링 시스템에 비해 많은 장점을 가지고 있다. Smart-pipe를 도입하기 위해서는 상수관 파괴를 미리 예측하여 갑작스러운 상수관 파괴를 막는 것과 같이 smart-pipe 설치를 통해 발생하는 간접적 이익의 정량화가 우선되어야 한다. 그러나 이와 관련된 연구는 국내외적으로 매우 미비한 실정이다. 본 연구에서는 smart-pipe의 개념을 기존 상수관 모니터링 시스템과 비교하였으며 smartpipe 설치에 따른 이익을 수용가불편시간으로 정량화하는 방안을 제시하였다. 제안된 방법을 고양시의 상수관망에 적용하여 적용성을 검증하였으며, smart-pipe시스템의 도입을 위한 기초자료로 활용될 수 있을 것으로 판단되었다.

• Nuclear Engineering and Technology
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• 제52권1호
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• pp.59-68
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• 2020

ECCMIX component was introduced in RELAP5/MOD3 for calculating the interfacial condensation. Compared to other existing components in RELAP5, user experience of ECCMIX component is restricted to developmental assessment applications. To evaluate the capability of the ECCMIX component, ECCS experiment was conducted which included single-phase and two-phase thermal mixing. The experiment was carried out with test sections containing a main pipe (70 mm inner diameter) and a branch pipe (21 mm inner diameter) under the atmospheric pressure. The steam mass flow in the main pipe ranged from 0 to 0.0347 kg/s, and the subcooled water mass flow in the branch pipe ranged from 0.0278 to 0.1389 kg/s. The comparison of the experimental data with the calculation results illuminated that although the ECCMIX component was more difficult to converge than Branch component, it was a more appropriate manner to simulate interfacial condensation under two-phase thermal mixing circumstance, while the two components had no differences under single-phase circumstance.

• 한국가스학회지
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• 제27권2호
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• pp.1-6
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• 2023

시공 편의성 및 경제성 측면에서 장점이 있는 PE배관은 국내 도시가스 분야에서 지하 매설용으로 많이 사용되고 있다. 이러한 PE배관은 유지·보수 공사 중 가스 흐름을 차단하기 위해 많은 현장에서 스퀴즈오프를 활용하고 있다. 스퀴즈오프란 PE배관을 압착하여 유체 흐름을 차단하는 방법을 말하며 물리적인 힘에 의해 배관의 변형이 일어나는 공사의 특성상 손상이 발생할 수 있다. 본 연구에서는 스퀴즈오프에 따른 PE배관의 손상방지를 위해 압축률에 따른 손상평가 및 기밀시험을 통해 적정한 압축의 범위와 사용 압력, 관경 등의 스퀴즈오프 작업 절차에 반영될 주요 사항들을 도출하였다. PE배관 손상평가를 위한 압축 실험은 압축률(20%~40%)과 사용압력 (2.8kPa, 25kPa, 70kPa), 관경(63mm, 90mm, 110mm)을 변화시키면서 실시하였다. 압축률에 따른 손상평가 결과, 과도한 압축에 따른 영향을 분석하기 위한 압축률인 45%(110mm), 73%(63mm)인 배관에서 파손이 발생하였다. 또한, 스퀴즈오프 작업 중 기밀시험은 Ar(아르곤)을 이용하여 진행되었으며, 실험결과 70kPa의 조건과 110mm 의 배관 조건에서 누출이 발생하였다. 본 연구 결과, 기밀유지를 위한 스퀴즈오프는 25kPa이하의 사용압력 및 90mm 배관을 초과하지 않는 범위의 배관에서 작업을 실시해야하며 PE배관의 손상방지를 위한 적정 압축률은 30%임을 확인하였다. 이와같은 내용을 도시가스용 PE배관의 스퀴즈오프 작업 절차에 반영할 예정이다.

• 한국태양에너지학회 논문집
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• 제30권1호
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• pp.25-33
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• 2010

Use of daylight in underground space interacts with physiological need for human beings and provides relief from feeling secluded. Light pipe system can deliver natural light into the space where it is needed and can be used as primary or a secondary light source with benefits of energy, productivity and health. To use light pipe system effectively under various conditions, it is important to investigate the effectiveness of light pipe system with reliable monitoring protocol. This paper presents the results of light pipe system performance used in underground parking lot under different sky conditions. Comparisons were made between the illuminance standards of underground parking lot and the monitored data. The results indicated that adequate illuminance level was shown until 4.5m distance from the light pipe under clear sky condition. However, additional lighting device showed be used under overcast sky to meet the proper illuminance level.

• Journal of Welding and Joining
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• 제16권1호
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• pp.70-76
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• 1998

Most fossil power plants and many critical components will be approaching the end of their nominal design life. At the same time, utilities are finding it economically attractive to extend the use of these plants for several more years, Especially Main steam pipe that operated under high temperature and pressure, often under the more severe operating conditions associated with cycling duty, is most important pipe system and critical component in fossil power plant. To extend the viability of older pipe system and to improve the operation and maintenance reliability, some technologies of precise diagnosis and life management have evolved out of the necessity. The purpose of this study is to descrive the related technologies and show the example of one power plants. The purpose of this study is to descrive the related technologies and show the example of one power plants. The stress analysis was done using ANSYS FEM Code. The branch area from main steam to turbine was the high stressed zone. To evaluate the degradation of the pipe material, replica, visual check, magnetic test, hardness test were done at the welding spot. The degradation level of welding point was E/F, so the remaining life of the welded area was about 0-25%.

• 한국압력기기공학회 논문집
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• 제12권1호
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• pp.101-106
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• 2016

NSSS (Nuclear Steam Supply System) and BOP (Balance of Plant) design works for PGSFR (Prototype Gen-IV Sodium Fast Reactor) have been conducted in Korea. NSSS major components, e.g. reactor vessel, steam generator and secondary sodium main pipes, are designed according to the rule of ASME boiler and pressure vessel code division 5, in which DBA (Design by Analysis) methods are used in the stress assessments. However, there is little discussions about detail rules for BOP piping design. In this paper, the detail methodologies of BOP piping stress assessment are discussed including safety systems and non-safety system pipings. It is confirmed that KEPIC MGE(ASME B31.1) and ASME BPV code division 5 HCB-3600 can be used in stress assessments of non-safety pipes and class B pipes, respectively. However, class A pipe design according to ASME BPV code division 5 HBB-3200 has many difficulties applying to PGSFR BOP design. Finally, future development plan for class A pipe stress assessment method is proposed in this paper.

• Nuclear Engineering and Technology
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• 제53권4호
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• pp.1127-1133
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• 2021

A Spent Fuel Pool (SFP) is designed to store spent fuel assemblies in the pool. And, a SFP cooling and cleanup system cools the SFP coolant through a heat exchanger which exchanges heat with component cooling water. If the cooling system fails or interfacing pipe (e.g., suction or discharge pipe) breaks, the cooling function may be lost, probably leading to fuel damage. In order to prevent such an incident, it is required to properly cool the spent fuel assemblies in the SFP by either recovering the cooling system or injecting water into the SFP. Probabilistic safety assessment (PSA) is a good tool to assess the SFP risk when an initiating event for the SFP occurs. Since PSA has been focused on reactor-side so far, it is required to study on the framework of PSA approach for SFP and identify the key factors in terms of fuel damage frequency (FDF) through a case study. In this study, therefore, a case study of SFP-PSA on the basis of design information of APR-1400 has been conducted quantitatively, and several sensitivity analyses have been conducted to understand the impact of the key factors on FDF.

• 한국압력기기공학회 논문집
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• 제17권2호
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• pp.83-89
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• 2021

The thickness of pipe can be locally reduced during operation due to wall thinning. Due to its significance on structural integrity, many non-destructive detecting techniques and assessment methods are available. In this study, the elastic bending compliance of local wall-thinned pipe is presented in terms of the wall thinning geometry: wall thinning depth, circumferential angle and longitudinal length. Elastic finite element (FE) analysis further shows that the presented equation can be used for any wall thinning shape. The proposed solution differs from FE results by less than 6% for all cases analyzed. The bending compliance increases linearly with increasing longitudinal thinning length and non-linearly with increasing thinning angle and depth.