• 한국터널지하공간학회 논문집
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• 제19권1호
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• pp.57-70
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• 2017

본 연구에서는 광산이나 오일샌드 등의 분야에서 적용되고 있는 슬러리 파이프 마모량 측정 방법과 슬러리 파이프의 마모량 예측에 관련된 이론식들을 문헌연구를 통해 살펴보고, 실제 싱가포르 슬러리 쉴드 TBM 현장에서 주기적으로 측정한 직선부 슬러리 파이프의 두께 측정 자료로부터 평균 일일 마모율과 굴착거리당 마모율을 산정하였다. Bukit Timah Granite의 풍화등급에 따른 마모율을 구하였는데, 풍화토에 가까운 G (V) 등급 지반 및 G (III)/G (V)의 복합지반에서의 마모율이 G(I)~G (IV)의 암반 등급지반에 비해서 1.5배 높게 나타났다. 슬러리 파이프 마모율은 슬러리 운송속도에 비례하여 증가하는 경향을 보였다. 향후 지반특성 별 파이프 마모율과 합리적인 관리두께 선정을 통하여 보다 최적화된 슬러리 파이프의 교체 및 회전 주기를 산정할 수 있을 것으로 판단된다.

• 동력기계공학회지
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• 제5권3호
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• pp.73-79
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• 2001

The purpose of this investigation is experimentally to clarify the machinability and tool wear of STS 304 steel pipe material for piping. In order to determine the effects of cutting parameters and tool wear on thrust, torque, AE RMS, drilling is conducted on CNC milling machine. In this experiment, it is measured that thrust, torque, tool wear length, tool wear area and AE RMS during drilling using Hss tool. It has been found that a) During the drilling, the thrust and the torque of the STS 304 pipe are received more the effect of the feed than the spindle speed and the thrust increase with the increase of feed, b) The value of the AE RMS is been larger the effect of the cutting speed than the feed rate, and the value of the AE RMS increase with the increase of spindle speed, c) It has been found that the suitable feed in feed condition of 0.03, 0.05, 0.1, 0.15mm/rev is below 0.05mm/rev, d) The value of the AE RMS was shown a characteristic of the jump value during it was a sudden inrcrease of the tool wear. The increased character of the AE RMS value can be known an effective factor of the tool wear detection, and e) It can be quantitatively evaluated the condition of the tool according to calculate a area of the drill wear image which is obtained by a vision system.

• 청정기술
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• 제15권1호
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• pp.16-22
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• 2009

본 연구에서는 화력발전소에서 마모 및 주기적인 파손으로 문제가 발생하는 저회 운반용 주철관을 대체하기 위하여 내마모 성능이 우수한 FRP관을 개발하였다. 불포화 폴리에스테르, 비닐에스테르, 에폭시, 페놀 등4종의 수지와 탄화규소 내마모재를 사용하여 시편을 제작하고ASTM D4060 마모시험 및 분사식 마모시험을 수행하였다. ASTM D4060 마모시험에서는 최적의 수지 종류와 내마모재 크기, 내마모재와 수지의 혼합비율을 찾고 내마모성을 극대 화하였다. FRP와 주철을 비교한 시험에서는 FRP 시편이 주철 시편에 비하여 작은 마모량을 보여 주철관의 FRP 파이프로의 대체 가능성을 보여 주었다. 현장시험을 위하여 시제품 파이프를 제작한 후 기존 회처리라인에 적용한 결과 FRP관이 내마모성에서 기존의 주철관보다 우수함을 보여주었다.

• Nuclear Engineering and Technology
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• 제31권4호
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• pp.375-384
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• 1999

The credibility of CHECWORKS FAC model analysis was evaluated for plant application in a model plant chosen for demonstration. The operation condition at each pipe component was defined before the wear rate analysis by plant data base, water chemistry analysis, and network flow analysis. The predicted wear was compared with the measured wear for 57 sample components selected from 43 susceptible line groups analysed. The inspected 57 locations represent components of highest predicted wear in each line group. Both absolute value and relative ranking comparisons indicated reasonable correlations between the predicted and the measured values. Four components showed much higher measured wear rates than the predicted ones in the feed water train from main feed water pump discharge to steam generator, probably due to high hydrazine concentration operation the effect of which had not been incorporated into the CHECWORKS model. The measured wear was higher than the predicted one consistently for components with least susceptibility to FAC. It is believed that the conservatism maintained during UT data analysis dominated the measurement accuracy. A great deal of enhancement is anticipated over the current plant pipe management program when a comprehensive plant pipe management program is implemented based on the model analysis.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.33-36
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• 2007

The majority of fly ash pipes in thermal power stations use steel pipes. This makes frequent replacement inevitable due to severe abrasion near the hot and curved section of pipes. Recently, there have been efforts to prevent this abrasion with lining techniques using ceramic or basalt on the inner wall of the pipe. This study uses composite and anti-wear material to maximize the anti-abrasion effects on the hot section of the pipe. The thickness of the abrasion layer was determined by the abrasion ratio of material found through the experiment; the thickness of the reinforcement layer was determined by micromechanics. Experiments were conducted on epoxy resins to test for heat and abrasion. Anti-abrasion test using particle impingement was intended to recreate realistic conditions when abrasion occurs within the hot section of an actual pipe. This study analyzes the abrasion ratio obtained from both the specimen experiment and from on-site measurement and provides evidence that a combination of composites and anti-wear agent can be used to create a fly ash pipe that is lower in costs and higher in quality than what is used currently.

• 한국터널지하공간학회 논문집
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• 제26권3호
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• pp.243-254
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• 2024

현재 국내 지역의 산업 발달로 인해 주요 도심은 물론 주변 도시 지역에도 건축물이 포화 상태이다. 이에 따라 사람들의 관심은 지하공간으로 쏠리게 되었고, 특히 도시개발에 있어서 터널은 광범위하게 활용되고 있다. 이에 따라 터널 및 터널굴착공법에 대한 연구가 활발히 진행되고 있다. 그러나 이수식 쉴드 TBM 사용 시 슬러지 배출관의 마모 및 파손 문제에 대한 연구는 부족한 실정이다. 따라서 본 논문에서는 기존 슬러지 배출관에 사용된 L자형 곡관을 T자형 곡관으로 변형하여 슬러지를 이동시켰다. 그 결과, L자형 곡관에 비하여 T자형 곡관이 슬러지 배출 시 곡관에 미치는 영향이 감소하는 것을 확인할 수 있었다. 이러한 결과를 바탕으로 이수식 쉴드 TBM 장비 사용 시 T자형 곡관을 사용하면 슬러지 배출관의 마모를 최소화할 수 있을 것으로 기대된다. 이는 결국 터널 공사 시 곡관 교체나 추가 용접에 따른 비용을 절감하는 등 경제적 이익으로 이어질 것으로 기대된다.

• 대한전기학회논문지:시스템및제어부문D
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• 제55권3호
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• pp.131-137
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• 2006

The secondary system of nuclear power plants consists of sophisticated piping systems operating in very aggressive erosion and corrosion environments, which make a piping system vulnerable to the wear and degradation due to the several chemical components and high flow rate (~10 m/sec) of the coolant. To monitor the wear and degradation on a pipe, the vibration signals are measured from the pipe with an accelerometer For analyzing the vibration signal the time-frequency analysis (TFA) is used, which is known to be effective for the analysis of time-varying or transient signals. To reduce the inteferences (cross-terms) due to the bilinear structure of the time-frequency distribution, an adaptive cone-kernel distribution (ACKD) is proposed. The cone length of ACKD to determine the characteristics of distribution is optimally selected through an adaptive algorithm using the normalized Shannon's entropy And the ACKD's are compared with the results of other analyses based on the Fourier Transform (FT) and other TFA's. The ACKD shows a better signature for the wear/degradation within a pipe and provides the additional information in relation to the time that any analysis based on the conventional FT can not provide.

• Corrosion Science and Technology
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• 제11권4호
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• pp.129-134
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• 2012

UT(Ultrasonic Test), one of the non-destructive tests, is the most common thickness measurement method for evaluating the wear rate in NPPs(Nuclear Power Plants). UT is used widely because it is easy and safe for use. However some amount of error inevitably occurs in attempting to measure the thickness. The error, that could make the thickness data thicker or thinner, may affect estimation of wear rate in pipes. NPPs are composed of a lot of pipes and components. Some of them are tested to check the current status during RFO(Re-Fueling Outage). Reliability analysis of UT is essential for evaluating pipe wear rate and establishing the long-term management plan in NPPs. This paper reviewed the cause of error occurrence and presented the UT data reliability analysis method. Also, this paper shows the application result of reliability analysis to the UT data acquired in NPPs.

• Corrosion Science and Technology
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• 제14권1호
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• pp.1-11
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• 2015

Local wall thinning and integrity degradation caused by several mechanisms, such as flow accelerated corrosion (FAC), cavitation, flashing and/or liquid drop impingements, are a main concern in carbon steel piping systems of nuclear power plant in terms of safety and operability. Thinned pipe management program (TPMP) had been developed and optimized to reduce the possibility of unplanned shutdown and/or power reduction due to pipe failure caused by wall thinning in the secondary side piping system. This program also consists of several technical elements such as prediction of wear rate for each component, prioritization of components for inspection, thickness measurement, calculation of actual wear and wear rate for each component. Decision making is associated with replacement or continuous service for thinned pipe components. Establishment of long-term strategy based on diagnosis of plant condition regarding overall wall thinning is also essential part of the program. Prediction models of wall thinning caused by FAC had been established for 24 operating nuclear plants. Long term strategies to manage the thinned pipe component were prepared and applied to each unit, which was reflecting plant specific design, operation, and inspection history, so that the structural integrity of piping system can be maintained. An alternative integrity assessment criterion and a computer program for thinned piping items were developed for the first time in the world, which was directly applicable to the secondary piping system of nuclear power plant. The thinned pipe management program is applied to all domestic nuclear power plants as a standard procedure form so that it contributes to preventing an accident caused by FAC.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 추계학술대회 논문집
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• pp.493-497
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• 2002

In the part industry, pipe has required high accuracy in surface roughness and size. Especially, when producing the high frequency welding pipe, cutting process is very important as the finishing process that remove the hot welding bead. The objective of this paper is to investigate the hot machining high frequency welded pipe by simulation and experimental tests. To test the cutting process as hot machining, all cutting environment is reproduced in turning with heating system, and the test is accomplished by comparing with room temperature machining and hot machining in consideration of cutting force, tool wear and cutting temperature.