• Title, Summary, Keyword: Concentration Correction Factor

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Fatigue Strength Improvement and Fatigue Characteristics by TIG-Dressing on Weld Bead Toes (용접지단부 TIG처리에 의한 피로강도향상 및 피로특성)

  • Jung, Young Hwa;Kim, Ik Gyeom;Nam, Wang Hyone;Chang, Dong Huy
    • Journal of Industrial Technology
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    • v.20 no.A
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    • pp.169-178
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    • 2000
  • The 4-point bending tests have been performed In order to estimate the effect of TIG-dressing on fatigue strength and fatigue characteristics quantitatively for non load-carrying fillet welded joints subjected to pure bending. As a result of fatigue tests, fatigue strengths of as-welded specimens have satisfied the grade of fatigue strength prescribed in specifications of korea, AASHTO and JSSC. Fatigue strength at 2 million cycles of TIG-dressing specimens have increased compared with as-welded specimens. As the result of beachmark tests, fatigue cracks occurred at several points, where the radius of curvature and flank angle in the weld bead toes were low, and grew as semi-elliptical cracks, then approached to fracture. As a result of finite element analysis, stress concentration factor in weld bead toes has closely related to the flank angle and radius of curvature, and between these, the radius of curvature has more largely affected in stress concentration factor than flank angle. As a result of fracture mechanics approaches, the crack correction factor of test specimens has largely affected on stress gradient correction factor in case a/t is below 0.4. From the relations between stress intensity factor range estimated from FEM analysis and fatigue crack growth rate, fatigue life has been correctly calculated.

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The Effect of Column Height on Sludge-Water Interface Height Change Model (슬러지계면층높이변화모델에서 컬럼높이에 대한 영향)

  • Park, Suk Gyun;Kang, Seon-Hong
    • Journal of Korean Society of Water and Wastewater
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    • v.20 no.2
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    • pp.265-272
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    • 2006
  • While sludge settles down in a column, sludge settling characteristic is influenced by effect parameters, interparticle force, wall effect etc. As the height of a column changes, the settling velocity of sludge-water interface changes, too. At lower sludge concentration, particular effect was not observed by the difference of column height, however it was observed that settleability of sludge was greatly influenced by column height when sludge settling was poor or sludge concentration was high. It is therefore required to consider the effect of column height when the power model for sludge interface settling is established. In the tests, there was hardly any $SVI_{ts}$(SVI after "t" minutes) difference in each column after 10min at $1.5kg/m^3$ of sludge concentration. When sludge concentration was at $2.5kg/m^3$, $SVI_{ts}$ tended to be constant after 20min. At $3.5kg/m^3$, $SVI_{ts}$ increased to 30minuets. The purpose of this work is to establish the correction factor that is able to compensate the errors derived from each different height of column.

Fatigue Crack Growth Characteristics by the Cover Plate Shapes in the Steel Plate Girder (강판항(鋼板桁) 덮개판 형상에 따른 피로균열성장특성)

  • Jung, Young-Hwa;Kim, Ik-Gyeom;Jung, Jin-Suck;Lee, Hyung-Koon
    • Journal of Industrial Technology
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    • v.19
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    • pp.269-278
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    • 1999
  • When a variety of repeated loads are given, most steel structures failed in much lower level of loads than static failure loads. In addition, bridge always includes the internal defects or discontinuities. from these, fatigue cracks initiates and can lead to sudden failure. Thus, in this study, tensile specimens by the cover plate shapes were used as the test specimens. The fatigue test was performed by constant amplitude fatigue loading and beach mark. From the results of this study, each specimen's fatigue section was observed. in addition, stress intensity factor at crack tip was calculated by using the Green's function which applied to discontinuous section where causing stress concentration. Therefore, the fatigue life of structural detail was investigated by adopting the theories of fracture mechanics. each specimen's crack shape is a semi-elliptical surface crack or center crack sheet, stress gradient correction factor, Fg is the most subjective of all stress intensity correction factors and fatigue life should be predicted by previous proposed function and finite element analysis.

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Stress concentration factors for finite orthotropic graphite/E laminates with a circular hole (圓孔 이 있는 有限 直交異方性 Graphite / E Laminate 의 應力集中係數)

  • 홍창선
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.4 no.3
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    • pp.113-118
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    • 1980
  • Stresses were calculated for finite-width orthotropic laminates with a circular hole and remote uniaxial loading using a two-dimensional finite-element analysis with both uniform stress and uniform displacement boundary conditions. Five different laminates were analyzed: quasi-isotropic [0.deg./.+-.45.deg./90.deg.].$\_$s/, 0.deg., 90.deg., [0.deg./90.deg.]$\_$s/, and [.+-.45.deg.]$\_$s/, Computed results are presented for selected combinations of hole diameter-sheet-width ratio d/w and length-to width ratio L/w. For small L/w values, the stress-concentration factors K$\_$tn/ were significantly different for the uniform stress and uniform displacement boundary conditions. Typically, for the uniform stress conditions, the K$\_$tn/ values were much larger than for the infinite-strip reference conditions; however, for the uniform displacement conditon, they were only slighty smaller than for this reference. The results for long strips are also presented as width-correction factor. For d/w.leg.33, these width-correction factors are nearly equal for all five laminates.

Atmospheric correction algorithms for satellite ocean color data: performance comparison of "OCTS-type" and "CZCS-type" algorithms

  • Fukushima, Hajime;Mitomi, Yasushi;Otake, Takashi;Toratani, Mitshiro
    • Proceedings of the KSRS Conference
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    • pp.307-312
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    • 1998
  • The paper first describes the atmospheric correction algorithm for the Ocean Color and Temperature Scanner (OCTS) visible band data used at Earth Observation Center (EOC) of National Space Development Agency of Japan (NASDA). It uses 10 candidate aerosol models including "Asian dust model" introduced in consideration of the unique feature of aerosols over the east Asian waters. Based on the observations at 670 and 865 nm bands where the reflectance of the water body can be discarded, the algorithm selects a pair of aerosol models that accounts best for the observed spectral reflectances to synthesize the aerosol reflectance in other bands. The paper also evaluates the performance of the algorithm by comparing the satellite estimates of water-leaving radiance and chlorophyll-a concentration with selected buoy-and ship-measured data. In comparison with the old CZCS-type atmospheric correction algorithm where the aerosol reflectance is as-sumed to be spectrally independent, the OCTS algorithm records factor 2-3 less error in estimating the normalized water-leaving radiances. In terms of chlorophyll-a concentration estimation, however, the accuracy stays vey similar compared to that of the CZCS-type algorithm. This is considered to be due to the nature of in-water algorithm which relies on spectral ratio of water-leaving radiances.

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Atmospheric correction algorithms for satellite ocean color data: performance comparison of "CTS-type" and "CZCS-type" algorithms (위성해색자료의 대기보정 알고리즘 : OCTS-type과 CZCS-type 알고리즘의 성능비교)

  • Hajime Fukushima;Yasushi Mitomi;Takashi Otake;Mitsuhiro Toratani
    • Korean Journal of Remote Sensing
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    • v.14 no.3
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    • pp.262-276
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    • 1998
  • The paper first describes the atmospheric correction algorithm for the Ocean Color and Temperature Scanner (OCTS) visible band data used at Earth Observation Center (EOC) of National Space Development Agenrr of japan (NASDA). It uses 10 candidate aerosol models including "Asian dust model" introduced in consideration of the unique feature of aerosols over the east Asian waters. Based on the observations at 670 and 865 nm bands where the reflectance of the water body can be discarded, the algorithm selects a pair of aerosol models that accounts best for the observed spectral reflectances to synthesize the aerosol reflectance in other bands. The paper also evaluates the performance of the algorithm by comparing the satellite estimates of water-leaving radiance and chlorophyll-a concentration with selected buoy- and ship-measured data. In comparison with the old CZCS-type atmospheric correction algorithm where the aerosol reflectance is assumed to be spectrally independent, the OCTS algorithm records factor 2-3 less error in estimating the normalized water-leaving radiances. In terms of chlorophyll-a concentration estimation, however, the accuracy stays very similar compared to that of the CZCS-type algorithm. This is considered to be due to the nature of in-water algorithm which relies on spectral ratio of water-leaving radiances.

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An Effect of TIG Dressing on Fatigue Characteristics of Non Load-Carrying Fillet Welded Joints (TIG처리에 따른 하중비전달형 필렛용접부의 피로특성)

  • Jung, Young Hwa;Kyung, Kab Soo;Hong, Sung Wook;Kim, Ik Gyeom;Nam, Wang Hyone
    • Journal of Korean Society of Steel Construction
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    • v.12 no.5
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    • pp.617-628
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    • 2000
  • In this study, the 4-point bending test has been performed in order to estimate the effect of TIG-dressing on fatigue strength and fatigue characteristics quantitatively for non load-carrying fillet welded joints subjected to pure bending. As a result of fatigue tests, fatigue strength of as-welded specimens has been satisfied the grade of fatigue strength prescribed in specifications of domestics and AASHTO & JSSC, and fatigue strength at $2{\times}106cycles$ of TIG-dressing specimens has been increased compared with as-welded specimens. As the result of beachmark tests, fatigue cracks have been occurred at several points, where the radius of curvature and flank angle in the weld bead toes are low, and grown as semi-elliptical cracks, then approached to fracture. As a result of finite element analysis, stress concentration factor in weld bead toes has been closely related to the flank angel and radius of curvature, and between these, the radius of curvature has more largely affected in stress concentration factor than flank angle. As a result of fracture mechanics approaches, the crack correction factor of test specimens has been largely affected on stress gradient correction factor in case a/t is below 0.4. From the relations between stress intensity factor range estimated from FEM analysis and fatigue crack growth rate, fatigue life has been correctly calculated.

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Determination of Neutron Absorption Fraction Factor in Manganese Sulfate Bath System (황산망간 용액조 장치의 중성자 흡수분율 보정인자 결정)

  • Lee, Kyung-Ju;Park, Kil-Oung;Hwang, Sun-Tae;Lee, Kun-Jai
    • Nuclear Engineering and Technology
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    • v.21 no.1
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    • pp.12-17
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    • 1989
  • The correction factor of neutron fraction absorbed by $^{55}$ Mn in the MnSO$_4$ bath was determined for the absolute measurement of neutron emission rate by using the solution circulation-type manganese sulfate bath system. For the determination of this correction factor, I/f, the atomic number desnsity and the effective neutron capture cross section data of Mn, S and impurity elements in the MnSO$_4$ solution were determined. For the atomic number density determination, the MnSO$_4$ solution concentration was determined by using the volumetric EDTA titration and gravimetric method. The impurity contents were analyzed by using the ICP method. For the calculation of effective neutron capture cross sections, a FORTRAN computer program EASCAL was developed in this study. in which Westcott's parameters and Axton's empirical relations are used.

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Comparative Experiment to Determine the Activation Factor of Lead dioxide by Kinds in Measuring the Concentration of Sulfur oxides in the Atmosphere by $PbO_2$ Cylinder Method (사용시약별로 본 이산화연법에 의한 대기중 황산화물의 비교측정및 자동측정 성적과의 비교)

  • 최덕일
    • Journal of Environmental Health Sciences
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    • v.2 no.1
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    • pp.29-31
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    • 1975
  • This experiment Was carried out under two points of view, from May 1st to the end of 1973. One was the comparative determination of the activation factor of Lead dioxide by kinds in measuring of Sulfur oxides concentration by $PbO_2$ cylinder method, and the other was the comparison that result with the record of auto analyzer. Five measuring sites were selected out of Seoul City. Three kinds of Lead dioxide made in Japan (B,C and D) were compared with Standard $PbO_2$ (A for use in Determination of Sulphur in the atmosphere, purity 99% up) made in British Institution, and monthly measuring was conducted at every sampling site. The recording by auto analyzer (Beckman Model 906-A $SO_2$ Analyzer) was conducted once or twice a month for 24 hours at each sampling site during the same period. And some significant results were obtained. 1. In comparative experiments to determine the activation degree of three kinds of Lead dioxide (B,C and D), the obtained correction factor of B reagent was 1.09, 1.16 in C and 1.30 in D against Standard $PbO_2$ (A). Therefore, it should be in need of standardization or clear statement about the reagents for use, in determination sulfur oxides by $PbO_2$ cylinder method. 2. Generally, the concentration of Sulfur dioxide by wilkins' convertion method from $SO_3$ showed about 20-30% higher than those by Auto analyzer.

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Extraction of Exact Layer Thickness of Ultra-thin Gate Dielectrics in Nanoscaled CMOS under Strong Inversion

  • Dey, Munmun;Chattopadhyay, Sanatan
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.10 no.2
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    • pp.100-106
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    • 2010
  • The impact of surface quantization on device parameters of a Si metal oxide semiconductor (MOS) capacitor has been analyzed in the present work. Variation of conduction band bending, position of discrete energy states, variation of surface potential, and the variation of inversion carrier concentration at charge centroid have been analyzed for different gate voltages, substrate doping concentrations and oxide thicknesses. Oxide thickness calculated from the experimental C-V data of a MOS capacitor is different from the actual oxide thickness, since such data include the effect of surface quantization. A correction factor has been developed considering the effect of charge centroid in presence of surface quantization at strong inversion and it has been observed that the correction due to surface quantization is crucial for highly doped substrate with thinner gate oxide.