• 제목/요약/키워드: residual variation

검색결과 491건 처리시간 0.026초

잔류공기조건에 따른 관 내 유동의 압력변화에 관한 실험적 연구 (An Experimental Study of Pressure Variation in Pipe Flow according to Residual Air Condition)

  • 박재곤;이경수;고주석;류시완
    • 한국안전학회지
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    • 제37권4호
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    • pp.113-119
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    • 2022
  • Sudden intrusion of a large amount of surface water into a flood defensive tunnel or pipeline system can compress the residual air. The compressed air may explode along with water through the inlet or air vent, resulting in hydraulic capacity degradation or safety hazards. This study aims to investigate the behavior of compressed air body in pipelines according to the residual air condition with a series of laboratory experiments measuring pressure variation. It has been found that flow characteristics and residual air conditions have a dominant influence on the magnitude and periodicity of the pressure variation. A proper measure to effectively control the residual air is required for securing the design capacity of flood defensive pipeline systems, since the peak pressure is predominantly affected by residual air conditions.

Genetics of Residual Feed Intake in Cattle and Pigs: A Review

  • Hoque, M.A.;Suzuki, K.
    • Asian-Australasian Journal of Animal Sciences
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    • 제22권5호
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    • pp.747-755
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    • 2009
  • The feed resource for animals is a major cost determinant for profitability in livestock production enterprises, and thus any effort at improving the efficiency of feed use will help to reduce feed cost. Feed conversion ratio, expressed as feed inputs per unit output, is a traditional measure of efficiency that has significant phenotypic and genetic correlations with feed intake and growth traits. The use of ratio traits for genetic selection may cause problems associated with prediction of change in the component traits in future generations. Residual feed intake, a linear index, is a trait derived from the difference between actual feed intake and that predicted on the basis of the requirements for maintenance of body weight and production. Considerable genetic variation exists in residual feed intake for cattle and pigs, which should respond to selection. Phenotypic independence of phenotypic residual feed intake with body weight and weight gain can be obligatory. Genetic residual feed intake is genetically independent of its component traits (body weight and weight gain). Genetic correlations of residual feed intake with daily feed intake and feed conversion efficiency have been strong and positive in both cattle and pigs. Residual feed intake is favorably genetically correlated with eye muscle area and carcass weight in cattle and with eye muscle area and backfat in pigs. Selection to reduce residual feed intake (excessive intake of feed) will improve the efficiency of feed and most of the economically important carcass traits in cattle and pigs. Therefore, residual feed intake can be used to replace traditional feed conversion ratio as a selection criterion of feed efficiency in breeding programs. However, further studies are required on the variation of residual feed intake during different developmental stage of production.

잔류응력에 의한 피로균열면 형상변화 및 수명예측 (Fatigue Crack shape Variations by a Residual Stress and Fatigue Life Predition)

  • 강용구;서창민;박원종
    • 한국해양공학회지
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    • 제7권2호
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    • pp.68-78
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    • 1993
  • Fatigue crack shape variation by a residual stress during crack growth and life predition are studied. An analytical method is presented to predict the influence of a residual stress due to heattreatment on crack shape variations. Computer simulation results using this me thod are graphically shown that crack growth rate to surface direction are decreased due to compressive residual stress exisiting in surface area. These results are commpared with experimental results. The fatigue life is also predicted by computer simulation of crack aspect ratio variation which is based on the surface crack length increment per unit cycle calculated from a-N diagram. Predited life is about 12 percent lower than experimental life.

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광도만에 있어서 물질수송과정의 수치예측

  • 이인철;류청로
    • 한국해양공학회:학술대회논문집
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    • 한국해양공학회 2000년도 추계학술대회 논문집
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    • pp.159-164
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    • 2000
  • In order to clarify the seasonal variation of residual current and material transportation process in Hiroshima Bay, JAPAN, the real-time simulation of residual current and particle tracking by using Euler-Lagrange model were carried out. The calculated tidal current and water temperature and salinity showed good agreement with the observed ones. The residual currents showed the southward flow pattern at the upper layer, and the northward flow pattern at the lower layer. The flow structure of residual current in Hiroshima Bay is an estuarine circulation affected by density flow and wind driven current. The residual current plays an improtant role of material transportation in th bay.

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한국수영만에서 잔차류장의 운동 .위치에너지의 계절변화 (Seasonal Variation of Kinetic and Potential Energy of Residual Flow Field in Suyoung Bay, Korea)

  • 김동선;유철웅
    • 한국환경과학회지
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    • 제6권4호
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    • pp.313-322
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    • 1997
  • 한국수영만에서 잔차류장의 운동 위치에너지의 계절변화를 연구하기 위하여 우리는 에너지의 수지를 계산하고 조석에너지와 비교했다. 위치에너지는 겨울과 봄철에 크며, 밀도성층이 형성된 여름과 초가을에 작게 나타났다. 잔차류의 운동에너지는 계절적인 변화를 보이고 있으며, 단위면 적당 잔차류의 평균 운동에너지는 6.4$\times$$10^{-4}ergs s^{-1}cm^{-}2$이다. 수영 만에서 잔차류장의 계절변동은 조석잔차류의 운동에너지가 밀도류나 취송류의 운동에너지보다 큰 11월을 제외하고는 밀도류가 지배하고 있다. 잔차류의 주성분인 조석잔차류, 취송류 및 밀도류의 운동에너지의 평균백분율은 잔차류의 운동에너지에 대하여 각각 29.1%, 3.4%, 67.5% 이다. 단위면적당 잔차류의 운동에너지, 위치에너지 및 조석에너지의 비는 각각 1.0 : 6.7$\times$$10^3$ : 8.2$\times$$10^4$ 이다.

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Butt 용접판재에서의 피로균열성장거동에 미치는 잔류응력의 영향에 관한 연구 (A Study on the Influence Residual Stresses on Fatigue Crack Growth Behaviors in the Butt Welded Plate)

  • 차용훈;정종안;채경수;김하식
    • 한국안전학회지
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    • 제8권2호
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    • pp.64-71
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    • 1993
  • In this study, the purpose is to investigate the influence of initial residual stresses on the fatigue crack growth behaviors after the distribution of initial residual stresses Is measured when the crack is growing from the compressive residual stresses field to the tensile residual stress field. Also, the Influence of the variation of residual stress distribution on the fatigue crack growth behaviors at the crack tip is studied when the initial crack li applied on base metal, weld metal and HAZ respectively.

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Detection and Control of Variation Source for a Production Unit

  • Xu, Jichao;Akpolat, Hasan
    • International Journal of Quality Innovation
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    • 제4권1호
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    • pp.148-159
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    • 2003
  • Variation is the archenemy of quality. To reduce or control the variation in a complex production unit, firstly we need to identify the location of the root cause of the variation. This paper discusses the detection of variability and the techniques used for reduction of variation for a production unit consisting of many processes. In the first part of this paper, the background of variability detection in production systems is introduced which is then followed by a weighted network corresponding to correlation matrix of all processes. Based on the network and clustering criterion of maximum spanning tree, a classification of all processes is derived. Furthermore, the variation of each process in a class is determined by residual analysis. In the last part, the use of methods of robust design for the processes with a larger variability is discussed.

컴플라이언스법에 의한 다층 맞대기 이음의 잔류응력 추정 (Residual Stress Prediction in Multi-layer Butt Weld Using Crack Compliance Method)

  • 김유일;이장현
    • Journal of Welding and Joining
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    • 제30권6호
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    • pp.74-79
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    • 2012
  • It depends on the joint configuration, dimensions and constraints of the joint whether the residual stress at the root of single-sided butt weld is tensile or not. Therefore, recommendation is generally made that high R ratio should be used in the fatigue test of welded joint in order to prevent excessively long life caused by compressive residual stress. In this research, the residual stress profile in butt weld joint was obtained through compliance method, using successive extension of a slot and measurement of the variation of strain during the slot extension. The residual stress profile was firstly assumed to be the linear summation of Legendre polynomials up to 9th order excluding 0th and 1st order. Strain variation on the surface was measured while the slot was being extended by cutting to find out the 8 unknown coefficients of each polynomial term. The cut was made by the electric discharge machine. It was concluded that the residual stress near the surface is positive valued, however, it turned into the negative value as soon as it passed through 2 or 3 mm of the depth.

잔류응력 완화에 미치는 상변태의 수치적 모델링 (N.M.for the Effect of P.T. on Resicual Stress Relaxation)

  • 장경복;손금렬;강성수
    • Journal of Welding and Joining
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    • 제17권6호
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    • pp.84-89
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    • 1999
  • Most of ferrous b.c.c weld materials may experience martensitic transformation during rapid cooling after welding. It is well known that volume expansion due to the phase transformation could influence on the relaxation of welding residual stress. To apply this effect practically, it is a prerequisite to establish a numerical model which is able to estimate the effect of phase transformation on residual stress relaxation quantitatively. For this purpose, the analysis is carried out in two regions. i.e., heating and cooling, because the variation of material properties following a phase transformation in cooling is different in comparison with the case in heating, even at the same temperature. The variation of material properties following phase transformation is considered by the adjustment of specific heat and thermal expansion coefficient, and the distribution of residual stress in analysis is compared with that of experiment by previous study. consequently, in this study, simplified numerical procedures considering phase transformation, which based on a commercial finite element package was established through comparing with the experimental data of residual stress distribution by other researcher. To consider the phase transformation effect on residual stress relaxation, the transition of mechanical and thermal property such as thermal expansion coefficient and specific heat capacity was found by try and error method in this analysis.

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대구 지역의 계절 변화에 따른 급수관내 잔류염소 농도 거동 (The Seasonal Variation of Free Chlorine Residuals by Water Supply Distance in Daegu)

  • 이태관
    • 상하수도학회지
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    • 제19권3호
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    • pp.363-369
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    • 2005
  • This paper presents the integrated technique of water quality analysis and Geographic Information System(GIS) for assessing the variation of free chlorine residuals by water temperature and supply distance in Sangri water supply system in Daegu. GIS was utilized for mapping projectmap, extraction of a pipeline route, and supply distance. Free chlorine residual is analyzed every month for appraising the seasonal variation. As a result, free chlorine residuals are affected both water temperature and water supply distance, and it becomes worse as water temperature and water supply distance is increased. To maintain 0.4mg/l of free chlorine residual, initial dose concentration should be over 1.85mg/l in summer.