• Title/Summary/Keyword: Wear model

검색결과 561건 처리시간 0.026초

Technology to reduce water ingress for TBM cutterhead intervention

  • Ham, Soo-Kwon;kim, Beom-Ju;Lee, Seok-Won
    • Geomechanics and Engineering
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    • 제29권3호
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    • pp.321-329
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    • 2022
  • Tunnel site where high water pressure is applied, such as subsea tunnel, generally selects the shield TBM (Tunnel Boring Machine) to maintain the tunnel excavation face. The shield TBM has cutters installed, and the cutters wear out during the process of excavation, so it should be checked and replaced regularly. This is called CHI (Cutterhead Intervention). The conventional CHI under high water pressure is very disadvantageous in terms of safety and economics because humans perform work in response to high water pressure and huge water inflow in the chamber. To overcome this disadvantage, this study proposes a new method to dramatically reduce water pressure and water ingress by injecting an appropriate grout solution into the front of the tunnel face through the shield TBM chamber, called New Face Grouting Method (NFGM). The tunnel model tests were performed to determine the characteristics, injection volume, and curing time of grout solution to be applied to the NFGM. Model test apparatus was composed of a pressure soil tank, a model shield TBM, a grout tank, and an air compressor to measure the amount of water inflow into the chamber. The model tests were conducted by changing the injection amount of the grout solution, the curing time after the grout injection, and the water/cement ratio of grout solution. From an economic point of view, the results showed that the injection volume of 1.0 L, curing time of 6 hours, and water/cement ratio of the grout solution between 1.5 and 2.0 are the most economical. It can be concluded that this study has presented a method to economically perform the CHI under the high water pressure.

$Cu-TiB_2$ 나노 금속복합재의 물성치에 대한 연구 (Study on material properties of $Cu-TiB_2$ nanocomposite)

  • 김지순;장명규;염영진
    • Composites Research
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    • 제19권2호
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    • pp.28-34
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    • 2006
  • 고온자전합성법과 스파크 플라즈마 소결법으로 여러 가지 $TiB_2$ 함유량을 갖는 $Cu-TiB_2$ 금속복합재료를 제조하였다. 점용접 전극과 미끄럼 접촉재로 사용하기 위해 인장특성, 경도, 마모저항 등의 물성치를 조사하였다. 강화재의 형상, 크기, 부피분율 등에 의해 복합재료의 특성이 달라지므로 유효물성치를 예측하기 위한 모델링이 필수적이다. 유한요소해석결과 유효탄성 계수가 실험치와 일치하는 것을 확인하였고 Eshelby 모델, Mori-Tanaka의 평균장 이론이 결합된 Eshelby 모델, 혼합법칙 등으로 복합재료의 탄성계수를 예측한 결과 Mori-Tanaka의 평균장 이론이 결합된 Eshelby 모델이 실험치를 사장 잘 묘사하는 것으로 나타났다.

가변축 사용여부에 따른 연료소모량 비교 연구 (A Comparative Study on Fuel Consumption Depending on The Use of Lift Axle)

  • 오주삼;어효경
    • 한국도로학회논문집
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    • 제13권3호
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    • pp.185-193
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    • 2011
  • 가변축은 대형화물자동차에 주로 장착되는 보조차축으로써, 물류비용 절감과 도로포장면 파손방지, 유류비 등의 차량운행비용 절감을 목적으로 도입되었다. 그러나 유류비절감 측면에 대한 가변축의 사용효과가 실증적 실험을 통해 입증되지 않았을 뿐만 아니라, 일부 운전자들의 막연한 기대심리로 인한 잘못된 가변축 활용사례가 발생되고 있다. 본 연구에서는 가변축 사용 여부에 따른 연료소모량 변화를 확인하고자 실제 도로주행 실험을 수행하였으며, 실험결과를 바탕으로 연료소모원단위 모형을 개발 및 적용하여 가변축 사용여부별 연료소모량을 비교하였다. 그 결과, 가변축을 사용하지 않을 시에 연료소모량 감소가 예상되었으며, 수치상으로 공차주행 시 -0.83%, 만차주행 시 -2.15%를 나타내었다. 공차주행 시 절감율은 제도의 효과를 정량적으로 나타내는 수치로써, 금액으로 환산 시 약 300억 원에 달한다.

셔터 글래스 방식 3D 영상에서의 PDP-TV 화질 보상 (Picture Quality Compensation for PDP-TV in Shutter-Glass type 3D Image)

  • 최석권;이인수;김광태
    • 전자공학회논문지
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    • 제51권2호
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    • pp.133-140
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    • 2014
  • 최근 3D 디스플레이에 대한 개발이 활발히 이루어지고 있고, 그 중 셔터 글래스나 편광 글래스 이용한 3D 영상 기술이 주류를 이루고 있다. 그 중에서 셔터 글래스 방식의 경우 3D 안경의 영향으로 3D 시청 시 인지하는 휘도, 컬러 선명도(colorfulness) 그리고 선예도(sharpness)가 현저히 줄어들게 된다. 본 논문에서는 3D 시청 시 인지하는 채도를 CIECAM02 model을 이용하여 3D안경으로 인한 화질의 열화 정도를 평가하고 분석하였다. 이러한 과정을 통하여 셔터 글래스 방식의 3D PDP-TV를 3D 모드에서 시청시, 컬러 선명도와 선예도에 대한 손실에 대하여 결과를 도출하고, 이 결과를 토대로 3D 모드에서의 최적화된 화질 구현을 위한 컬러 선명도와 선예도를 보상하는 방안을 제안하고 실험을 진행하였다.

환경친화적인 극성기유와 첨가제(TCP)의 상호작용모델로부터 해석된 Polyalkylene glycol 및 Polyolester Base Oil의 윤활작용 (Lubricating Performance of Polyalkylene Glycol and Polyolester Base Oils analyzed from the Model of Interaction between Environmentally adapted Polar base oils and Additive (TCP))

  • 한두희
    • Tribology and Lubricants
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    • 제17권2호
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    • pp.146-152
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    • 2001
  • Environmentally adapted synthetic base oils of polyalkylene glycols (PAGs) and polyol esters (POEs) show a high polarity because of their functional groups containing oxygen atom. The lubricating performance of these polar base oils was investigated by using a four-ball tribometer under boundary lubrication condition. Four polyalkylene glycols and five polyol ester base oils were used as sample base oils of high polarity. A mineral oil (MO) and alkylnaphthalene (AN) were used as low polarity base oils. Tricrecylphosphate (TCP) was added to all the base oils, in the range of 10 mmol/L-2000 mmol/L, as an antiwear additive. All the TCP-for-mutated base oils showed optimum concentration characteristics for minimizing wear. The order of optimum concentration of all the base oils was in a good accordance with the order of relative stability of TCP in base oils. The interaction model on solvation between additive and different polar base oils can expect the stability order of TCP. Thus, the model on solvation can explain well the order of optimum concentration of all the base oils, by using the effect of polarity (dielectric constant, $\varepsilon$) and molecular size (molecular weight, MW) of them on stability of TCP in polar base oils. Finally, a good correlation of the optimum concentration for all the base oils was obtained when it was arranged as a function of C∝(M $W_{Base Oil}$/M $W_{TCP}$)$^{-2}$.71/.($\varepsilon$$_{Base Oil}$)$^{3.38}$ by these two parameters.s..

FLUID-STRUCTURE INTERACTION IN A U-TUBE WITH SURFACE ROUGHNESS AND PRESSURE DROP

  • Gim, Gyun-Ho;Chang, Se-Myoung;Lee, Sinyoung;Jang, Gangwon
    • Nuclear Engineering and Technology
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    • 제46권5호
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    • pp.633-640
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    • 2014
  • In this research, the surface roughness affecting the pressure drop in a pipe used as the steam generator of a PWR was studied. Based on the CFD (Computational Fluid Dynamics) technique using a commercial code named ANSYS-FLUENT, a straight pipe was modeled to obtain the Darcy frictional coefficient, changed with a range of various surface roughness ratios as well as Reynolds numbers. The result is validated by the comparison with a Moody chart to set the appropriate size of grids at the wall for the correct consideration of surface roughness. The pressure drop in a full-scale U-shaped pipe is measured with the same code, correlated with the surface roughness ratio. In the next stage, we studied a reduced scale model of a U-shaped heat pipe with experiment and analysis of the investigation into fluid-structure interaction (FSI). The material of the pipe was cut from the real heat pipe of a material named Inconel 690 alloy, now used in steam generators. The accelerations at the fixed stations on the outer surface of the pipe model are measured in the series of time history, and Fourier transformed to the frequency domain. The natural frequency of three leading modes were traced from the FFT data, and compared with the result of a numerical analysis for unsteady, incompressible flow. The corresponding mode shapes and maximum displacement are obtained numerically from the FSI simulation with the coupling of the commercial codes, ANSYS-FLUENT and TRANSIENT_STRUCTURAL. The primary frequencies for the model system consist of three parts: structural vibration, BPF(blade pass frequency) of pump, and fluid-structure interaction.

청소년의 종가 생활문화 현장학습프로그램 개발을 위한 종가 복식문화 사례 연구 -전남 함평 종가를 대상으로- (A Case Study on the Costume Culture of the Head Family for Adolescent′s Spot Experience Studying)

  • 서리나;유명의
    • 복식문화연구
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    • 제11권5호
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    • pp.753-766
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    • 2003
  • The purpose of this study was to examine the cases of the family head's costume culture and to apply them to field experience education of adolescent's home economics subject. To examine the family head's costume culture, women in the family head in the Hampyeong area, Jeollanam-do were selected and interviewed. The focus of examining the family head's costume culture was on the life story of the family head, the reason to wear or possess such costume, and a motive of making. The findings of the head family's costume culture suggests that the head family of the Mos of Hampyeong had unique shroud making and custom. Also it was found that the eldest daughters-in-law of the Lees of Hampyeong have horizontally exchanged the information of the family head's costume with village women of the same family. They have initiated their costume culture directly through their daughters and it had the great influence on after-ages. The learning program for youth to experience the head family's costume culture consisted of four subjects:(l)Educating the family head's traditional living culture including etiquette training, (2)head family village walk, (3)experiencing the family head's clothes life including natural dyeing and sewing, and (4)a field trip of Hampyeong Local Life Culture Museum. For a model experience of the family head's costume life culture, three families with middle and high schoolers participated in 8- hour experience learning program. To examine the effect of learning program to experience the family head's costume culture, youth and their parents who participated in the program were asked open-ended questions, which included the content validity of experience learning, impressive experience, model experience level(difficulty), and expected effect after a model experience. As a result, their responses were found positive.

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항공엔진 열화데이터 기반 잔여수명 예측력 향상을 위한 데이터 전처리 방법 연구 (A study on Data Preprocessing for Developing Remaining Useful Life Predictions based on Stochastic Degradation Models Using Air Craft Engine Data)

  • 윤연아;정진형;임준형;장태우;김용수
    • 산업경영시스템학회지
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    • 제43권2호
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    • pp.48-55
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    • 2020
  • Recently, a study of prognosis and health management (PHM) was conducted to diagnose failure and predict the life of air craft engine parts using sensor data. PHM is a framework that provides individualized solutions for managing system health. This study predicted the remaining useful life (RUL) of aeroengine using degradation data collected by sensors provided by the IEEE 2008 PHM Conference Challenge. There are 218 engine sensor data that has initial wear and production deviations. It was difficult to determine the characteristics of the engine parts since the system and domain-specific information was not provided. Each engine has a different cycle, making it difficult to use time series models. Therefore, this analysis was performed using machine learning algorithms rather than statistical time series models. The machine learning algorithms used were a random forest, gradient boost tree analysis and XG boost. A sliding window was applied to develop RUL predictions. We compared model performance before and after applying the sliding window, and proposed a data preprocessing method to develop RUL predictions. The model was evaluated by R-square scores and root mean squares error (RMSE). It was shown that the XG boost model of the random split method using the sliding window preprocessing approach has the best predictive performance.

전단변형과 시간변화 이동자기력을 고려한 레일의 강제진동모델링 (Forced Vibration Modeling of Rail Considering Shear Deformation and Moving Magnetic Load)

  • 김준수;김성종;이혁;하성규;이영현
    • 대한기계학회논문집A
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    • 제37권12호
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    • pp.1547-1557
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    • 2013
  • 시간변화 이동자기력이 작용하는 레일의 변형을 티모센코 보 이론(Timoshenko beam theory)로 가정하였으며, 보의 진동특성에 영향을 미치는 탄성체기초의 감쇠효과 및 강성을 고려하였다. 푸리에 급수와 수치해석을 이용해 강제진동모델의 동적응답과 임계속도를 구하였다. 레일의 진동모델을 유한요소 해석 및 오일러 보 이론(Euler beam theory)과 비교 검증하였다. 강제진동모델을 이용하여 레일의 영구변형을 예측하였으며, 실험결과 레일표면의 영구변형 및 마모를 확인하였다. 보의 설계변수인 레일의 형상, 재료, 탄성체 기초의 감쇠효과 및 강성이 레일의 임계속도 및 레일의 처짐, 축 방향 응력, 전단 응력에 미치는 영향에 대한 매개변수적 연구를 진행하였으며, 보의 설계방향을 얻을 수 있었다.

토크와 드래그를 고려한 시추궤도 모델링 연구 (Well Trajectory Modelling Considering Torque and Drag)

  • 김지훈;최준형;김도영;박태일;이대성
    • 한국지반환경공학회 논문집
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    • 제24권1호
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    • pp.51-60
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    • 2023
  • 수직 시추와 다르게 방향성 시추작업에서 발생하는 드릴스트링(drill string) 변형, 케이싱(casing) 마모, 키 씨팅(key seating) 등의 문제를 방지하기 위해서는 시추 궤도 내에서 발생하는 토크(torque)와 드래그(drag)가 최소화되어야 한다. 토크와 드래그의 크기는 시추 궤도 형태, 이수(mud), 드릴스트링의 종류 그리고 킥오프 지점(KOP, kick-off point)과 같은 매개변수들에 의해 결정되기 때문에 시추 궤도 설계 과정에서 고려하여 설계하여야 한다. 본 연구에서는 가장 일반적인 방향성 시추 궤도인 빌드-홀드(Build-hold) 형태의 시추 궤도에 킥오프 지점이 각기 다른 시추 궤도를 선정하였고, 분포하중 모델(analytical friction model)을 이용하여 각 구간내에서의 분포하중을 계산하여 궤도 전체에 대한 토크와 드래그를 계산하였다. 또한 매개변수에 따른 분석 값을 비교하여 분포하중이 최소로 발생하는 최적의 시추 궤도를 선정하였다. 분석결과 분포 하중을 최소화하기 위해서는 윤활성이 높은 이수를 사용, 궤도 형태에 따른 알맞은 킥오프 지점과 가능한 최소의 도그-래그를 지정하여 설계하는 것이 효과적임을 알 수 있었다. 이러한 결과는 분포하중을 최소화하기 위한 모든 방향성 시추 궤도 설계에 사용된다.