• Title/Summary/Keyword: growth time

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A Study on Transition From Cycle-dependent to Time-dependent Crack Growth in SUS304 Stainless Steel (SUS304강의 사이클의존형에서 시간의존형균열성장으로의 천이에 관한 연구)

  • 주원식;조석수
    • Journal of Welding and Joining
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    • v.14 no.1
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    • pp.38-46
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    • 1996
  • High temperature low cycle fatigue crack growth behavior is investigated over a range of two temperatures and various frequencies in SUS 304 stainless steel. It is found that low frequency and temperature can enhance time-dependent crack growth. With high temperature, low frequency and long crack length, ${\Delta}J_c/{\Delta}J_ f$, the ratio of creep J integral range to fatigue J integral range is increased and time-dependent crack growth is accelerated. Interaction between ${\Delta}J_f$ and ${\Delta}J_c$ is occured at high frequency and low temparature and ${\Delta}J_c$, creep J integral range is fracture mechanical parameter on transition from cycle-dependent to time dependent crack growth in creep temperature region.

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A Clinical Evaluation of the Tumor Volume Doubling Time in Primary Bronchogenic Carcinoma (폐암환자에서 본 Tumor Doubling Time 의 임상적 의의)

  • 홍기우;이홍균
    • Journal of Chest Surgery
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    • v.6 no.1
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    • pp.15-22
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    • 1973
  • The definition of cancer, its diagnosis and its prognosis all depend upon description of growth. To the layman a synonym for cancer is a "growth". There are no quantitative terms for the description of growth or growth rate in clinical use. There has been no attempt to assign values that would define "rapidly" or "slowly" growing. Estimates of growth potentiality are implied in the descriptive phrases "poorly differentiated" or "well differentiated", "highly malignant" or "low grade malignancy". and in systems of grading. These qualifying terms represent a personal impression, clinically useful in prognosis, but relative in nature. They do not lend themselves to uniform application or precise measurement for purpose of comparison. Growth is related to size and time. The volume of tumor depends upon the duration of the period of growth and the rate of growth. If the interval and change in volume are known. the average growth rate can be determined. If the growth rate is determined, and assumed to be constant., the duration of a given tumor and the time of inception can be estimated. The commonest concept of the origin of cancer is that as a result of a mutation involving a single cell, succeeding divisions of cells establish a colony with the characteristics recognizable as cancer. If the growth rate of the hypothetical tumor were constant it could be described in terms of "tumor volume doubling time". In the department of thoracic surgery of St. Mary hospital in Catholic Medical College, a clinical evaluation for the growth rate, degree of malignancy, resectability and prognosis was done on a total 24 cases of primary bronchogenic carcinoma which contour was significant on the chest X-ray film as possible estimating the tumor volume doubling time. The following results were obtained: 1. In the cases of 6.0cm or more in diameter of minor size at operation the resectability rate was lower and in the cases of 60 days or more in the tumor or volume doubling time the resectability rate was higher. 2. If differentiation of cancer cells was lower graded in tissue pathology, the tumor volume was shorter and the resectability rate was lower. 3. The tumor volume doubling time of the primary bronchogenic carcinoma occured more over 60 years of age was slightly shorter than under 60 years of age. 4. The tumor size at operation was more important to evaluate the survival time and prognosis than the tumor volume doubling time because the tumor growth was not always constant, we presume.mor volume doubling time because the tumor growth was not always constant, we presume.

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Comparison of long-term forecasting performance of export growth rate using time series analysis models and machine learning analysis (시계열 분석 모형 및 머신 러닝 분석을 이용한 수출 증가율 장기예측 성능 비교)

  • Seong-Hwi Nam
    • Korea Trade Review
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    • v.46 no.6
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    • pp.191-209
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    • 2021
  • In this paper, various time series analysis models and machine learning models are presented for long-term prediction of export growth rate, and the prediction performance is compared and reviewed by RMSE and MAE. Export growth rate is one of the major economic indicators to evaluate the economic status. And It is also used to predict economic forecast. The export growth rate may have a negative (-) value as well as a positive (+) value. Therefore, Instead of using the ReLU function, which is often used for time series prediction of deep learning models, the PReLU function, which can have a negative (-) value as an output value, was used as the activation function of deep learning models. The time series prediction performance of each model for three types of data was compared and reviewed. The forecast data of long-term prediction of export growth rate was deduced by three forecast methods such as a fixed forecast method, a recursive forecast method and a rolling forecast method. As a result of the forecast, the traditional time series analysis model, ARDL, showed excellent performance, but as the time period of learning data increases, the performance of machine learning models including LSTM was relatively improved.

A Class of Discrete Time Coverage Growth Functions for Software Reliability Engineering

  • Park, Joong-Yang;Lee, Gye-Min;Park, Jae-Heung
    • Communications for Statistical Applications and Methods
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    • v.14 no.3
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    • pp.497-506
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    • 2007
  • Coverage-based NHPP SRGMs have been introduced in order to incorporate the coverage growth behavior into the NHPP SRGMs. The coverage growth function representing the coverage growth behavior during testing is thus an essential factor of the coverage-based NHPP SRGMs. This paper proposes a class of discrete time coverage growth functions and illustrates its application to real data sets.

Growth and Physiology of Thiobacillus novellus under Autotrophic and Heterotrophic Conditions (자가영양과 타가영양 조건하에서 Thiobacillus novellus의 생리 및 성장)

  • 박인국
    • Korean Journal of Microbiology
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    • v.29 no.4
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    • pp.263-266
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    • 1991
  • The growth of T. novellus in auto trophic and geterotrophic media was studied to determine the time required for cells to enter stationary phase and relative percentage of ribosomal proteins. When T. novellus was grown autotrophically, growth proceeded at a slow rate characteristic of autotrophs and did not enter log phase until the end of the first day. Logarithmic growth proceeded for 3-4 days at which time the cells entered the stationary phase. In particular, logarithmic growth was accompanied by decreasing pH of culture media and in the stationary phase the pH levelled off at 6.0, a decrease of 1.6 pH value compared to original pH of media. The pH decrease was greatest during log phase when cells oxidized thiosulfate to $H_{2}$$SO_{4}$. The doubling time was about 26h. In heterotrophic media growth proceeded at a much faster rate and cells entered stationary phase 20-22h after inoculation. The doubling time was 3h. The protein content of the ribosomes in T. novellus grown heterotrophically was 4.2% greater than those from the organism grown autotrophically.

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CREEP-FATIGUE CRACK GROWTH AND CREEP RUPTURE BEHAVIOR IN TYPE 316 STAINLESS STEELS- EFFECT OF HOLD TIME AND AGING TREATMENT

  • Mi, J.W.;Won, S.J.;Kim, M.J.;Lim, B.S.
    • International Journal of Automotive Technology
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    • v.1 no.2
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    • pp.71-77
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    • 2000
  • High temperature materials in service are subjected to mechanical damage due to operating load and metallurgical damage due to operating temperature. Therefore, when designing or assessing life of high temperature components, both factors must be considered. In this paper, the effect of tensile hold time on high temperature fatigue crack growth and long term prior thermal aging heat treatment on creep rupture behavior were investigated using STS 316L and STS 316 austenitic stainless steels, which are widely used for high temperature components like in automotive exhaust and piping systems. In high temperature fatigue crack growth tests using STS 316L, as tensile hold time increased, crack growth rate decreased in relatively short tensile hold time region. In long term aged specimens, cavity type microcracks have been observed at the interface of grain boundary and coarsened carbide.

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The Effect of Loading Waveform on the High Temperature Fatigue Crack Propagation in P92 and STS 316L Steel (P92와 STS 316L강의 고온 피로 균열 성장에 미치는 하중 파형의 영향)

  • 김수영;임병수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.4
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    • pp.136-140
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    • 2002
  • High temperature fatigue crack growth behavior of P92 and STS 316L steel were investigated under four load conditions using CT type specimens. Loading and unloading times for the low wave forms were combinations of 1 sec. and 50 sec., which were two symmetric wave forms and two unsymmetric wave forms. Their behaviors are characterized using ΔK parameter. In STS 316L, Crack growth rate generally increases as frequency decreases. However, sensitivity of the loading rate to crack growth rate was fecund to be far greater than that of the unloading time. It is because as loading time increases, creep occurs at crack tip causing the crack growth rate to increase. However creep does not occur at the crack tip even if the unloading time is increased. In P92 steel, crack growth rate showed same behavior as in STS 316L. But the increase in loading or unloading time made almost no difference in crack growth rate, suggesting that no significant creep occurs in P92 steel even though loading time increases. After conducting high temperature tensile tests and comparing high temperature fatigue crack growth rates under various wave forms, it was proved that P92 steel has not only good high temperature properties but also improved, better high temperature fatigue properties than STS 316L.

Long-run Equilibrium Relationship Between Financial Intermediation and Economic Growth: Empirical Evidence from Philippines

  • MONSURA, Melcah Pascua;VILLARUZ, Roselyn Mostoles
    • The Journal of Asian Finance, Economics and Business
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    • v.8 no.5
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    • pp.21-27
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    • 2021
  • The financial sector is one of the most important building blocks of the economy. When this sector efficiently implemented a well-crafted program on banking and financial system to translate financial activities to income-generating activity, economic growth will be realized. Hence, this study analyzed the effect of financial intermediation on economic growth and the existence of cointegrating relationship using time-series data from 1986 to 2015. The influence of financial intermediation in terms of bank credit to bank deposit ratio, private credit, and stock market capitalization and time trend to economic growth was estimated using ordinary least squares (OLS) multiple regression. The results showed that all the financial intermediation indicators and time trend exert significant effect on Gross Domestic Product (GDP) per capita. The positive sign of the time trend indicates that there is an upward trend in GDP per capita averaging approximately 0.06 percent annually. Furthermore, the cointegration test using the Johansen procedure revealed that there is a presence of long-term equilibrium relationship between financial intermediation and time trend and economic growth, and rules out spurious regression results. This study established the idea that financial intermediation in the Philippines has a significant and vital role in stimulating growth in the economy.

As ZnO2 Thin Film Manufacturing Time Increases, the Thin Film Particle Growth Plane and a Study on the Direction of Particle Growth (ZnO2 박막 제조 시간의 증가에 따라 박막 입자 성장면과 입자 성장 방향에 관한 연구)

  • Jung, Jin
    • Journal of Integrative Natural Science
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    • v.14 no.1
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    • pp.1-5
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    • 2021
  • A zinc oxide thin film was made by varying the deposition time on the silicon(110) substrate by using a radio frequency sputtering time of 60 minutes, 120 minutes and 180 minutes. As a result of analyzing the grain growth surface of the ZnO2 thin film using an X-ray diffraction apparatus, the directions of the main growth plane (002) and (103) planes of the thin film were significantly affected by the deposition time. As a result of observing the particle growth of the ZnO2 thin film through an electron scanning microscope, it was observed that in the initial stage of deposition of the ZnO2 thin film, an incubation time was required during which growth was stagnant, and then particle growth occurred again after a certain period of time. As a result of chemical analysis of the ZnO2 thin film, the increase in the deposition time did not change with the amount of oxygen in the ZnO2 thin film, but a change in the composition of Zn was observed, indicating that the deposition time of the thin film had an effect on the Zn component in the thin film.

Growth of Time-Dependent Strain in Reinforced Cement Concrete and Pre-stressed Concrete Flexural Members

  • Debbarma, Swarup Rn.;Saha, Showmen
    • International Journal of Concrete Structures and Materials
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    • v.6 no.2
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    • pp.79-85
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    • 2012
  • This paper presents the differences in growth of time-dependent strain values in reinforced cement concrete (RCC) and pre-stressed concrete (PSC) flexural members through experiment. It was observed that at any particular age, the time-dependent strain values were less in RCC beams than in PSC beams of identical size and grade of concrete. Variables considered in the study were percentage area of reinforcement, span of members for RCC beams and eccentricity of applied pre-stress force for PSC beams. In RCC beams the time-dependent strain values increases with reduction in percentage area of reinforcement and in PSC beams eccentricity directly influences the growth of time-dependent strain. With increase in age, a non-uniform strain develops across the depth of beams which influence the growth of concave curvature in RCC beams and convex curvature in PSC beams. The experimentally obtained strain values were compared with predicted strain values of similar size and grade of plane concrete (PC) beam using ACI 318 Model Code and found more than RCC beams but less than PSC beams.