• 소음진동
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• 제7권4호
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• pp.631-636
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• 1997

A method to estimate the radiatio power to the surrounding formation due to axial vibration of the pipe in a fluid-filled borehole has been developed, by using the propagation modes of stress wave in an infinitely-long and uniform drilling borehole surrounded by a radially-infinite homogeneous formation. Also, the equivalent damping coefficient for the axial vibration of the pipe has been derived. As an example, results for a real drilling borehole has been presented. The analysis of the elastic motion of the infinite formation which has cylidrical cavity is simplified with the geometric axisymmetry and the low-frequency assumption so that the analytic solution is obtained.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.127-131
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• 2000

The paper presents both theoretical and experimental study for dynamic instabilities of a vertical cantilevered pipe with two attached lumped masses conveying fluid. The two attached lumped masses can be considered as valves or some mechanical parts in real pipe system. Eigenvalue behaviors depending on the flow velocity are investigated for the change of positions and magnitudes of an attached lumped mass and a tip mass. In order to verify appropriaty of numerical solutions, experiments were accomplished. Theoretical predictions have a good agreement with experimental ones.

• 한국정밀공학회지
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• 제22권6호
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• pp.83-89
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• 2005

Most domestic fossil power plants have exceeded 100,000 hours of operation with the severe operating condition. Among the critical components of fossil power plant, high temperature steam pipe systems have had a many problems and damage from unstable displacement behavior because of frequent start up and shut down. In order to prevent the serious damage and failure of the critical pipe system in fossil power plants, 3-dimensional displacement measurement system was developed for the on-line monitoring. Displacement measurement system was developed with a use of a LVDT type sensor and two rotary encoder type sensors. This system was installed and operated on the real power plant successfully.

• 한국소음진동공학회논문집
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• 제11권6호
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• pp.208-215
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• 2001

The paper presents both theoretical and experimental study fur dynamic instabilities of a vortical cantilevered pipe with two attached lumped masses conveying fluid. The two attached lumped masses can be considered as valves or some mechanical paras in real pipe systems. Eigenvalue behaviors depending on the flow velocity are investigated for the change of Positions and magnitudes of an attached lumped mass and a tip mass. In order to verify appropriate of numerical solutions, experiments were accomplished. Theoretical predictions have a good agreement with experimental ones.

• 상하수도학회지
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• 제37권6호
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• pp.347-361
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• 2023

Water utilities are making various efforts to reduce water losses from water networks, and an essential part of them is to recognize the moment when a pipe burst occurs during operation quickly. Several physics-based methods and data-driven analysis are applied using real-time flow and pressure data measured through a SCADA system or smart meters, and methodologies based on machining learning are currently widely studied. Water utilities should apply various approaches together to increase pipe burst detection. The most intuitive and explainable water balance method and its procedure were presented in this study, and the applicability and detection performance were evaluated by applying this approach to water supply pipelines. Based on these results, water utilities can establish a mass balance-based pipe burst detection system, give a guideline for installing new flow meters, and set the detection parameters with expected performance. The performance of the water balance analysis method is affected by the water network operation conditions, the characteristics of the installed flow meter, and event data, so there is a limit to the general use of the results in all sites. Therefore, water utilities should accumulate experience by applying the water balance method in more fields.

• 한국정보통신학회논문지
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• 제20권5호
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• pp.923-930
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• 2016

상 하수도, 해양플랜트 등 다양한 배관이 산업현장에 이용되고 있으며, 이러한 배관의 유지보수 작업은 필수적이다. 특히 산업현장에서 배관 유지보수 작업은 전문 인력이 배관 내 투입되어 작업이 진행되거나, 인력 투입이 불가능한 경우 와이어에 연결된 스크래퍼를 배관에 삽입하는 방식을 이용한다. 그러나 이 방식은 교통체증, 막대한 예산의 투입 등의 문제를 야기한다. 이런 문제점을 해결하기 위한 배관 청소 로봇의 연구, 개발이 진행되고 있다. 현재 배관청소 로봇은 작업 및 운용 상태를 실시간으로 확인할 수 없는 문제점이 있다. 본 논문에서는 배관 청소로봇의 운용, 배관 내부 및 청소 상태를 확인할 수 있도록 카메라로부터 촬영된 영상을 수집하며, 수집된 데이터는 RS-485 통신을 이용하여 모니터링 시스템에 전송하여 사용자가 실시간으로 상태를 확인할 수 있게 구성하였다.

• Journal of Microbiology and Biotechnology
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• 제21권2호
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• pp.115-123
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• 2011

To investigate the effects of pipe materials on biofilm accumulation and water quality, an annular reactor with the sample coupons of four pipe materials (steel, copper, stainless steel, and polyvinyl chloride) was operated under hydraulic conditions similar to a real plumbing system for 15 months. The bacterial concentrations were substantially increased in the steel and copper reactors with progression of corrosion, whereas those in stainless steel (STS) and polyvinyl chloride (PVC) reactors were affected mainly by water temperature. The heterotrophic plate count (HPC) of biofilms was about 100 times higher on steel pipe than other pipes throughout the experiment, with the STS pipe showing the lowest bacterial number at the end of the operation. Analysis of the 16S rDNA sequences of 176 cultivated isolates revealed that 66.5% was Proteobacteria and the others included unclassified bacteria, Actinobacteria, and Bacilli. Regardless of the pipe materials, Sphingomonas was the predominant species in all biofilms. PCR-DGGE analysis showed that steel pipe exhibited the highest bacterial diversity among the metallic pipes, and the DGGE profile of biofilm on PVC showed three additional bands not detected from the profiles of the metallic materials. Environmental scanning electron microscopy showed that corrosion level and biofilm accumulation were the least in the STS coupon. These results suggest that the STS pipe is the best material for plumbing systems in terms of the microbiological aspects of water quality.

• 대한기계학회논문집A
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• 제36권10호
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• pp.1227-1234
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• 2012

본 연구에서는 감육결함이 가공된 실배관 곡관 시편을 대상으로 10 MPa의 내압과 반복 굽힘하중 조건에서 피로 시험을 수행하였다. 시험에는 감육결함이 곡관의 외호부와 내호부에 존재하는 경우를 고려하였으며, 반복 하중으로는 완전 역방향의 변위제어 형태로 작용되는 In-plane 상의 굽힘하중이 고려되었다. 실험 결과, 감육결함이 곡관의 외호부에 존재하는 경우에는 결함부가 아닌 곡관의 측면에서 축방향 균열이 생성되었다. 또한, ASME Sec.III의 설계 피로곡선에서 예측된 건전 곡관의 피로수명보다 긴 피로수명을 보였으며, 피로수명이 결함 길이에 크게 영향을 받지 않았다. 반면, 결함이 내호부에 존재하는 곡관은 내호부에서 원주방향 균열이 발생하였으며, 피로수명은 ASME Sec.III의 설계 피로곡선에서 예측한 건전 곡관의 피로수명보다 짧은 값을 보였다. 또한, 내호부 감육 곡관의 피로수명은 결함 길이가 감소함에 따라 뚜렷이 감소하였다.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제3권10호
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• pp.329-336
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• 2014

플랜트 공사 현장에서 파이프 스풀은 플랜트 설비의 가장 중요한 요소이다. 현재 플랜트 공사장에서 파이프 스풀 관리는 수기 작성을 통해 적재 위치 및 작업 내역을 관리하고 있다. 그러나 현재 현장에서는 작업자의 임의적인 파이프 스풀의 이동과 제작 또는 설치해야 할 파이프 스풀을 찾지 못했을 경우 비슷한 파이프 스풀을 가지고 와 다시 제작하는 현상이 발생하고 있다. 이에 파이프 스풀의 위치를 정확하게 알 수 없기 때문에 파이프 스풀을 찾기 위한 인건비와 시간이 소요되며, 분실에 대한 관리가 되지 않는 상황이다. 이에 파이프 스풀에 UHF RFID 태그를 부착하고 차량에 UHF RFID 리더 및 안테나를 장착하여 파이프 스풀의 위치를 찾을 수 있는 시스템을 제안한다. 제안된 시스템을 활용하여 현장 테스트를 진행한 결과 98% 이상의 위치 정보 인식이 가능했으며, 손실된 2%의 미 인식 태그는 작업자에 의한 보정을 통해 100%의 관리가 가능함을 확인할 수 있었다. 향후 제안된 시스템 도입으로 인건비와 분실 파이프에 대한 관리가 원활하게 이루어질 뿐만 아니라 특정 공간에 적재되어있는 물품관리에도 활용될 것으로 전망한다.

• 설비공학논문집
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• 제19권8호
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• pp.599-606
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• 2007

An experimental study was performed to measure a ice concentration of ice slurry flowing in a pipe in a real time. In the present paper, we suggested a measuring method by a refractive index and compared it to other methods by a freezing point and a density. To measure the refractive index of the solution, ice particles in the ice slurry should be completely removed and a hydro-cyclone was introduced instead of a mesh. The measuring method through the refractive index coincided with the density method using the real-time solution density within ${\pm}5%$ error range, having the error range less than the other two methods. In the other hand, the measuring method through the density has a good resolution, but the result using the initial density of the solution was different more than 10% error from that using the real-time density. And it has an error range 1.5 times greater than the method through the refractive index.