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An Analysis on Aspects of Concepts and Models of Fraction Appeared in Korea Elementary Mathematics Textbook (한국의 초등수학 교과서에 나타나는 분수의 개념과 모델의 양상 분석)

  • Kang, Heung Kyu
    • Journal of Elementary Mathematics Education in Korea
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    • v.17 no.3
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    • pp.431-455
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    • 2013
  • In this thesis, I classified various meanings of fraction into two categories, i.e concept(rate, operator, division) and model(whole-part, measurement, allotment), and surveyed appearances which is shown in Korea elementary mathematics textbook. Based on this results, I derived several implications on learning-teaching of fraction in elementary education. Firstly, we have to pursuit a unified formation of fraction concept through a complementary advantage of various concepts and models Secondly, by clarifying the time which concepts and models of fraction are imported, we have to overcome a ambiguity or tacit usage of that. Thirdly, the present Korea's textbook need to be improved in usage of measurement model. It must be defined more explicitly and must be used in explanation of multiplication and division algorithm of fraction.

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Comparison of Linear-Quadratic Model, Incomplete-Repair Model and Marchese Model in Fractionated Carbon Beam Irradiation (탄소 빔 분할조사 시 Linear-Quadratic모델, Incomplete-Repair모델, Marchese 모델 결과 비교)

  • Choi, Eunae
    • Journal of the Korean Society of Radiology
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    • v.9 no.6
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    • pp.417-420
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    • 2015
  • We obtained Surviving Fraction (SF) after irradiation carbon beam to compare the applicability of the Linear-Quadratic model, Incomplete Repair model, Marchese model. Mathematica software(ver 9.0) used to calcurate parameters and compared result. LQ model could not explain the entire response of fractionated carbon beam irradiation. It becomes necessary to construct models that extend the LQ model of conventional radiotherapy for the carbon beam therapy. By combining both Potentially Lethal Damage Repair (PLDR) and Sublethal Damage Repair (SLDR) a new LQ model can develop that aptly modeled the cellular response to fractionated irradiation.

Numerical Modeling on Microsegregation with Tip-undercooling in Weld Metal of Binary Alloys (과냉을 고려한 2원계합금 용접용융부의 미시편적 거동에 대한 수치해석 모델링)

  • 박종민;박준민;이창희
    • Journal of Welding and Joining
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    • v.17 no.4
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    • pp.60-68
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    • 1999
  • The previously developed two dimensional model was modified in order to predict more accurately the degree of microsegregation and eutectic fraction on in weld metal whose solidification rate is very fast. The model employed the same assumptions with previous model but considered of a tip undercooling. The previously predicted microsegregation and eutectic fraction has the discrepancies between simulated and examined results in the weld metal solidification. The experiments for the weld metal solidification of 2024 A1 and Fe-Ni alloy were carried out in order to examine the reasonability and feasibility of this modified model. The concentration profile of the solute and eutectic fraction predicted by the simulation agreed well with those found from experimental works. According to the results, it was believed that the dendrite tip undercooling considered in the modified model be reasonable for predicting the degree of microsegregation more accurately in weld metla solidification. In the GTA welds, degree of dendrite-tip undercooling increases with increasing solidification rage(welding speed). This serves to increase the concentration of dendrite core and thus result in reducing the degree of segregation. And solid state diffusion(back diffusion) during solidification is very low in the weld metal solidification so that little additional homogenization of solute occurs during solidification. With consideration of tip undercooling this modified model can predict exactly degree of microsegregation and eutectic fraction from slow solidification(casting) to fast solidification(welding).

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The Role of the Ethylacetate Fraction from Hydnocarpi Semen in Acute Inflammation In Vitro Model

  • Lee, Geum Seon;Shim, Hong;Lee, Ki-Man;Kim, Seung Hyun;Yim, Dongsool;Cheong, Jae Hoon;Kang, Tae Jin
    • IMMUNE NETWORK
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    • v.12 no.6
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    • pp.291-295
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    • 2012
  • We previously reported that Hydnocarpi Semen (HS) has a wound healing effect on diabetic foot ulcer lesion in mice. In this study, ethylacetate (EtOAc) fraction from HS extract were evaluated for their wound healing activity by using in vitro acute inflammation model. GC and GC/MS analysis shows that the main constituents in EtOAc fraction are chaulmoogric acid, hydnocarpic acid, and gorlic acid. EtOAc fraction activated macrophages to increase the production of TNF-${\alpha}$. The fraction also increased the production of TGF-${\beta}$ and VEGF, which induced fibroblast activation and angiogenesis. These results suggest that the mechanism that the fraction helps to enhance healing of skin wound is possibly associated with the production of TNF-${\alpha}$, as well as secretion of VEGF, TGF-${\beta}$ and HS may have a new bioactive material for the treatment of skin wound.

GENERATION OF FOREST FRACTION MAP WITH MODIS IMAGES USING ENDMEMBER EXTRACTED FROM HIGH RESOLUTION IMAGE

  • Kim, Tae-Geun;Lee, Kyu-Sung
    • Proceedings of the KSRS Conference
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    • pp.468-470
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    • 2007
  • This paper is to present an approach for generating coarse resolution (MODIS data) fraction images of forested region in Korea peninsula using forest type area fraction derived from high resolution data (ASTER data) in regional forest area. A 15-m spatial resolution multi-spectral ASTER image was acquired under clear sky conditions on September 22, 2003 over the forested area near Seoul, Korea and was used to select each end-member that represent a pure reflectance of component of forest such as different forest, bare soil and water. The area fraction of selected each end-member and a 500-m spatial resolution MODIS reflectance product covering study area was applied to a linear mixture inversion model for calculating the fraction image of forest component across the South Korea. We found that the area fraction values of each end-member observed from high resolution image data could be used to separate forest cover in low resolution image data.

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Development of Estimation of Model for Mechanical Properties of Steel Fiber Reinforced Concrete according to Aspect Ratio and Volume Fraction of Steel Fiber (강섬유의 형상비와 혼입률에 따른 강섬유 보강 콘크리트 보의 역학적 특성 추정 모형 개발)

  • Kwak, Kae-Hwan;Hwang, Hae-Sung;Sung, Bai-Kyung;Jang, Hwa-Sup
    • Journal of The Korean Society of Agricultural Engineers
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    • v.48 no.3
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    • pp.85-94
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    • 2006
  • Practially useful method of steel fiber for construction work is presented in this study. The most important purpose of this study is to develop a model which can predict mechanical behavior of the structure according to aspect ratio and volume fraction of steel fiber. Experiments on compressive strength, elastic modulus, and splitting strength were performed with self-made cylindrical specimens of variable aspect ratios and volume fractions. The experiment showed that compressive strength was not in direct proportion to volume fraction which doesn't seem to have great influence over compressive strength. However, splitting strength showed almost direct proportion to aspect ratio and volume fraction. Improvement of optimal efficiency was confirmed when the aspect ratio was 70. Experiments on flexural strength, fracture energy, and characteristic length were carried out with self-manufactured beams with notch. As a result, increases of flexural strength, fracture energy, and characteristic length according to increase of volume fraction tend to be prominent when aspect ratio is 70. The steel fiber improves concrete to be more ductile and tough. Moreover, regression analysis was the performed and predictable model was developed after determining variables. With comparison and analysis of suggested estimated values and measured data, reliance of the model was verified.

Two Conserved Scalar Approach for the Turbulent Nonpremixed Flames (다중 혼합기 난류 비예혼합 연소시스템에 대한 수치모델링)

  • Kim, Gun-Hong;Kang, Sung-Mo;Kim, Yong-Mo;Ahn, Kook-Young
    • 한국연소학회:학술대회논문집
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    • pp.57-61
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    • 2003
  • In the combustion modeling of non-premixed flames, the mixture fraction conserved scalar approach is widely utilized because reactants are mixed at the molecular level before burning and atomic elements are conserved in chemical reactions. In the mixture fraction approach, combustion process is simplified to a mixing problem and the interaction between chemistry and turbulence could be modelled by many sophisticated combustion models including the flamelet model and CMC. However, most of the mixture fraction approach is restricted to one mixture system. In this study, the flamelet model based on the two-feed system is extended to the multiple fuel-feeding systems by the two mixture fraction conserved scalar approach.

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Viscoelastic behavior on composite beam using nonlinear creep model

  • Jung, Sung-Yeop;Kim, Nam-Il;Shin, Dong Ku
    • Steel and Composite Structures
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    • v.7 no.5
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    • pp.355-376
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    • 2007
  • The purpose of this study is to predict and investigate the time-dependent creep behavior of composite materials. For this, firstly the evaluation method for the modulus of elasticity of whole fiber and matrix is presented from the limited information on fiber volume fraction using the singular value decomposition method. Then, the effects of fiber volume fraction on modulus of elasticity of GFRP are verified. Also, as a creep model, the nonlinear curve fitting method based on the Marquardt algorithm is proposed. Using the existing Findley's power creep model and the proposed creep model, the effect of fiber volume fraction on the nonlinear creep behavior of composite materials is verified. Then, for the time-dependent analysis of a composite material subjected to uniaxial tension and simple shear loadings, a user-provided subroutine UMAT is developed to run within ABAQUS. Finally, the creep behavior of center loaded beam structure is investigated using the Hermitian beam elements with shear deformation effect and with time-dependent elastic and shear moduli.

The Prediction of Void Fraction in the Subcooled Boiling Region (서브쿨드 비등 영역에서의 기포계수 계산에 관한 연구)

  • Goon Cherl Park
    • Nuclear Engineering and Technology
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    • v.16 no.4
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    • pp.195-201
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    • 1984
  • A state-of-the-art mechanistic model has been developed to accurately predict the void fraction in the subcooled boiling region having axial nonuniform heat flux. In this study, the void-dependent drift-flux parameters of the Lahey/Ohkawa model were introduced and the mass flux-dependent condensation coefficient were determined by fitting with the experimental data. This model was tested against several experimental data sets to verify its accuracy. Finally the comparison between the predicted void fraction profiles with this model and the profile-fit model for the hot assembly of Kori-Unit 1, Cycle 1 has been performed. It is conclusive that the results show the good agreement between the measured and predicted void fractions, and the profile-fit model has been found to underestimate the void fraction in the subcooled boiling region.

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Anticancer Effect of Hydrophobic Protein Fraction from Red Ginseng by Clonogenic Assay (Clonogenic Assay에 의한 홍삼 소수성단백질 분획의 항암효과)

  • Kim, Chang-Han;Lee, Myung-Sub;Lee, Kyung-Ho
    • Journal of Ginseng Research
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    • v.19 no.1
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    • pp.27-30
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    • 1995
  • We established the model of clonogenic assay with cancer cell lines such as SW-156(kidney), SNU-5(stomach), Hep G2(liver), and WiDr(colon), and we investigated anticancer effect of hydrophobic protein fraction(N-fraction) from Korea red ginseng by using this model. The results of clonogenic assay showed that N-fraction had anticancer activity against SNU-5 above 100 $0.2\mu\textrm{g}$/ml concentration, and did not exhibit anticancer activity against cell lines such as SW-156, WiDr, and Hep G2 up to 1,000 $\mu\textrm{g}$/ml concentration. This result suggests that N-fraction has specially anti-stomach cancerous effect.

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