• Title/Summary/Keyword: Initial growth rate

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Effect of Specimen Thickness to Corrosion Fatigue Crack Propagation Behavior of Structure Rolled Steel (일반구조용 압연강재의 부식피로균열전파거동에 미치는 시험편 두께의 영향)

  • 조약래
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.28 no.3
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    • pp.286-294
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    • 1992
  • In this paper, the corrosion fatigue crack propagation behavior of structure rolled steel (SWS 41C) was investigated by changing the thickness, and this experiment was done by the three point bending corrosion fatigue tester. The main results obtained are as follows: 1) As the thickness of specimen becomes thicker, the corrosion sensitivity to initial stage crack becomes some sensitive, and that the fatigue life becomes more sensitive. 2) The crack growth rate to initial stage crack (da/dN) was retarded as the thickness of specimen becomes thicker. But after initial stage crack, as the thickness of specimen is more thicker, da/dN is more rapid. 3) As the corrosion fatigue crack length grows, the accelerative factor of thick specimen (t=12mm) is more higher than that of thin specimen (t=6mm). 4) As the corrosion fatigue crack length grows, the corroson potential of both thick specimen and thin specimen becomes more less noble potential, however thick specimen (t=12mm) tends to more less noble potential than that of thin specimen(t=6mm).

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Permeation Characteristics of Wastewater Containing Si Fine Particles through Ultrafiltration

  • Park, Ho-Sang;Park, Young-Tae;Lee, Seok-Ki
    • Korean Membrane Journal
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    • v.5 no.1
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    • pp.31-35
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    • 2003
  • The permeation characteristics of the wastewater containing Si fine particles were examined by ultrafiltration using the polyolefin tubular membrane module. Flux with time was due to the growth of Si cake deposited on the membrane surface and the pore plugging by fine particles. The rate of flux decline in the initial stage increased with the trans-membrane pressure. The pore blocking resistance was the dominant resistance at the initial period of filtration and the cake resistance began to dominate with the initial pore blocking resistance. The larger pores compared with the fine particles, the more the membrane pores could be blocked by the fine particles. Before and after treatment, the distribution of particle size was shifted toward to the left. Then, the average size of fine particles in the permeate was 20 nm.

Seedling Emergence and Initial Growth between Water and Dry Seeding in Forage Millet (사료용 피의 건답과 무논 파종 시 입모 및 초기생육특성)

  • Ahn, Seok-Hyeon;Chung, Nam-Jin
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.59 no.1
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    • pp.83-88
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    • 2014
  • This research was carried out to determine the characteristics of germination in relation to temperature, and seedling emergence and growth affected by soil moisture in forage millet. The seeds of forage millet could germinate at more than $15^{\circ}C$ at the rate of 0, 90.5, 97.3 and 96.8% respectively 10 days after seeding at 10, 15, 20 and $25^{\circ}C$. The result showed that the temperature needs to be $15^{\circ}C$ or more for the seeds to germinate. The effects of seeding depth on the growth characteristics and emergence of millet seed were investigated in waters and direct seeding methods by thoroughly mixing the seed and soil. In water treatment, the emergence rates were 3.7% at $15^{\circ}C$, 7.6% at $20^{\circ}C$, 6.3% at $25^{\circ}C$, while direct seeding treatment showed the emergence rates of 65.6, 75 and 71% at 15, 20 and $25^{\circ}C$, respectively. At 15, 20, and $25^{\circ}C$, seeds in water seeding could germinate at 0.5, 1.8, 1.5 cm of soil depth, while in direct seeding, they could germinate at the depth of 9.5, 10.0, 9.9 cm. When the initial growth characteristics of the seeds were investigated, there was positive correlation between seeding depth and mesocotyl length in both water and direct seed methods. Growth and development in terms of leaf age, root length, coleoptiles and mesocotyl length, and plant height were found maximum at 0.5 cm soil depth for water seeding, and 3-5 cm soil depth for direct seeding. Results showed that there were close relationship among temperature, soil depth and moisture acquiring methods, and the combination of these factors greatly affected the initial growth characteristics and development of millet seeds. It can be concluded that, to get good seedling stand and germination of millet seed, millet should grown in field condition at the depth of 0.5 cm or less for water seeding, and 3-5 cm for direct seeding method.

The Growth-Curve Analysis of Tobacco in Various Cultivation Types (잎담배의 재배방법에 따른 생장 분석에 대하여)

  • 김윤동;김용암
    • Journal of the Korean Society of Tobacco Science
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    • v.2 no.2
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    • pp.44-50
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    • 1980
  • The growth of flue-cured tobacco was analyzed with the mathematical treatment. The results are summarized as followings: 1. The growth curve was fitted to the quadratic polynomial equation in improved-mulching cultivation, blot to the Gompertz equation in the other cultivations. 2. The initial point of the maximum growth phase for dry weight was about 50 days after transplanting in improved-mulching cultivation, but about 40 days in the other cultivations, and the maximum growth period was for 25 days in all cultivations. 3. The growth rate of the maximum growth period in dry weight decreased in the order of improved-mulching cultivation, mulching cultivation, and non-mulching cultivation. 4. A relative growth amount in the maximum growth period was higher in later sowing. 5. The length of maximum growth was 5 days shorter in leaf area than in dry weight. The maximum growth phase was 7 days earlier in leaf area than in dry weight.

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A study on the growth morphology of AlN crystals grown by a sublimation process (승화법으로 성장된 AlN 결정의 성장 양상에 관한 연구)

  • Kang, Seung-Min
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.19 no.5
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    • pp.242-245
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    • 2009
  • AlN crystals were grown by a sublimation process without seed crystals and the growth morphology of them was characterized. The grown AlN crystals were a polycrystalline phase, which had a diameter of $60\sim200\;{\mu}m$ and were grown with a growth rate of $0.2\sim0.5\;{\mu}n/hr$. It was observed that the as-grown crystals had a hexagonal crystal structure and revealed that these crystals were grown with a morphology of columnar morphology in the initial stage of the growth before they were enlarged in a way of a lateral growth behavior in the final stage. On the surface, a lot of pinholes were observed on the surface of crystals grown. The evolution of a growth morphology was characterized by optical and scanning electron microscopic observation.

Linear Stability Analysis in a Gas Turbine Combustor Using Thermoacoustic Models (열음향 해석 모델을 통한 가스터빈 연소기에서의 선형 안정성 분석)

  • Kim, Daesik
    • Journal of the Korean Society of Combustion
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    • v.17 no.2
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    • pp.17-23
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    • 2012
  • In this study, thermoacoustic analysis model was developed in order to predict both eigenfrequencies and initial growth rate of combustion instabilities for lean premixed gas turbine combustors. As a first step, a model combustor and nozzle were selected and analytical linear equations for thermoacoustic waves were derived for a given combustion system. Then, methods showing how the equations can be used for analysis of the combustion instability were suggested. It was found that the prediction results showed a good agreement with the measurements. However, there were some limitation in growth rate predictions, which were related with over-simplification of flame structure, acoustic boundary conditions, and temperature distribution in the combustor.

Proposal for various Social Field Participation of Korean Young Dentist (변화하는 사회와 치과의사의 공공기관 참여 제한)

  • Chang, Young-Il
    • The Journal of the Korean dental association
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    • v.49 no.1
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    • pp.7-14
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    • 2011
  • The purpose of this study is to discuss the economic outlook of dentistry in relation to pessimistic economic perspectives of Korea and to present subsequent solutions. The expectation of the future economic growth rate of Korea is gloom with not only a love rate of increase in population due to an aging society and a low birthrate, but also with a declined number of productive populations. Moreover, the future of dentistry in Korea is obscure. Even with a dwindling population growth, an average of 750 new dentists graduate from dental school every year. The 30-35% of the new graduates practice in public hospitals; and 65~70% of them open up their own private practices, However, unlike in the past, the occurrence of dental practice bankruptcy has been increasing with a competitive environment, excessive initial investment, knowledgeable patients, and etc. Therefore, it is essential to re-evaluate the number of new graduates. Also, it is necessary to supply a greater number of public hospitals with newly licensed dentists, who have various clinic experience, participate in research and development, and experience appropriate hospital management skills.

A Study on the Feature of Using Media for Education through Longitudinal Data Analysis (종단자료 분석을 통한 청소년 미디어 교육 활용 특성 분석 연구)

  • Heo, Gyun
    • Journal of Internet Computing and Services
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    • v.21 no.4
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    • pp.77-85
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    • 2020
  • The purpose of this study is to explore the changing trajectory of using educational media through longitudinal data analysis. We categorize the feature of using educational media as usage for learning, usage for information, and usage for the game. We explore the longitudinal changing patterns of usage for learning, usage for information, and usage for the game by LGM(Longitudinal Growth Modeling). We also find the gender difference between these longitudinal changing trajectories. We used 3,499 samples of KYPS middle school second-grade panel data. We found these results: (a) Both usage for learning and information are statically significant variability in initial level and rate of change. Both of the changing trajectories have increased. (b) Girls have a higher rate of the change both in the usage of learning and information than boys over time. (c) There is a statistically significant individual variability in initial levels and rate of change in the usage of the game over time. (d) Boys have a higher rate of initial value than girls in the usage of games, but there is no significant difference in the rate of changing trajectories.

Structure of Oxide Film Prepared by Two-step Anodization of Aluminum

  • Ko, Eunseong;Ryu, Jaemin;Kang, Jinwook;Tak, Yongsug
    • Corrosion Science and Technology
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    • v.5 no.4
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    • pp.137-140
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    • 2006
  • The effect of pre-existing barrier-type film on porous aluminum oxide film formation during anodization was investigated to control the uniform film growth rate. Initial potential fluctuations during anodization indicated that the breakdown of barrier-film is preceded before the porous formation and the induction time for the porous film growth increases with the increases of pre-existing film thickness. The porous film growth mechanism is lot affected by the presence of barrier film on aluminum surface. In parallel, uniform growth of barrier film underneath the porous structure was attained by two-step anodization processes.

Crack Growth Behavior of Tensile Overload for Small Load Amplitude at High-Low Block Stress Ratio (고-저블럭 응력비에서 하중진폭이 작은 인장과대 하중의 균열성장 거동)

  • 김엽래
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1997.10a
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    • pp.120-126
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    • 1997
  • This paper examines the crack growth behavior of 7075-T651 aluminum alloy under high-low block loading condition. The cantilever beam type specimen with a chevron notch is used in this study. The crack growth and closure are investgated by compliance method. The applied initial stress ratios are R=-0.5, R=0.0 and R=0.25 Crack length($\alpha$), effective stress intensity factor range(ΔKeff), ratio of effective stress intensity factor range(U) and crack growth rate(d$\alpha$/dN) etc. are inspected fracture mechanics estimate.

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