• 제목/요약/키워드: diffusion

검색결과 11,202건 처리시간 0.036초

The Quantitative Diffusion-Tensor Anisotropy of Human Brain Using Fast STEAM DTI

  • 박현정;황문정;김용선;이상권;장용민
    • 대한자기공명의과학회:학술대회논문집
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    • 대한자기공명의과학회 2001년도 제6차 학술대회 초록집
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    • pp.138-138
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    • 2001
  • Purpose: To obtain quantitative diffusion-tensor anisotropy information of human cerebral structu using turbo STEAM diffusion-tensor imaging. Method: Quantitative diffusion anisotropy MR images were obtained in 7 healthy adults using turbo STEAM sequence and a combination of tetrahedral and orthogonal diffusi gradients. Both relative anisotropy(RA) and fractional anisotropy(FA) values were measured various brain regions. The anisotropy index was then compared with the reported valu resulting from EPI-based diffusion tensor imaging.

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The Diffusion Tensor Imaging of Muscle Preliminary Results

  • 황문정;박현정;장용민;강덕식
    • 대한자기공명의과학회:학술대회논문집
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    • 대한자기공명의과학회 2001년도 제6차 학술대회 초록집
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    • pp.167-167
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    • 2001
  • Purpose: To obtain normative human skeletal muscle data and evaluate quantitative diffusion-ten anisotropy information using diffusion-tensor imaging technique. Method: Quantitative extremity muscle diffusion tensor MR images were obtained in 5 healt adults by using turbo STEAM sequence and a combination of tetrahedral and orthogon diffusion gradients. Relative anisotropy(RA) and fractional anisotropy(FA) values we measured in soleus and gastrocnemius muscle in addition to mean ADC value.

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콘크리트 내 이산화탄소 확산계수 예측에 관한 연구 (Diffusivity of Carbon Dioxide in Concrete)

  • 오병환;정상화;이명규
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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    • pp.669-674
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    • 2003
  • The purpose of this study is to identify the diffusion coefficients of carbon dioxide for various concrete mixtures. The test results indicate that the diffusion coefficient increases with the increase of water-cement ratio. The diffusion coefficient decreases with the increase of relative humidity at the same water-cement ratio. The diffusion of carbon dioxide reached the steady-state within about five hours after exposure. It was found that the diffusion coefficient of cement paste is larger then that of concrete or mortar. The quantitative values of diffusivity of carbon dioxide in this study will allow more realistic assessment of carbonation depth in concrete structures.

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ON THE MARTINGALE PROBLEM AND SYMMETRIC DIFFUSION IN POPULATION GENETICS

  • Choi, Won;Joung, Yoo-Jung
    • Journal of applied mathematics & informatics
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    • 제28권3_4호
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    • pp.1003-1008
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    • 2010
  • In allelic model $X\;=\;(x_1,\;x_2,\;\cdots,\;x_d)$, $$M_f(t)\;=\;f(p(t))\;-\;\int_0^t\;Lf(p(t))ds$$ is a P-martingale for diffusion operator L under the certain conditions. In this note, we define $T_tf\;=\;E_{p_0}^{p^*}\;[f((P(t))]$ for $t\;{\geq}\;0$ for using a new diffusion operator $L^*$ and we show the diffusion relations between $T_t$ and diffusion operator $L^*$.

적응성 유한체적법을 적용한 다차원 확산공정 모델링

  • 이준하;이흥주;변기량
    • 한국반도체및디스플레이장비학회:학술대회논문집
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    • 한국반도체및디스플레이장비학회 2004년도 춘계학술대회 발표 논문집
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    • pp.55-58
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    • 2004
  • This paper presents a 3-dimensional diffusion simulation with adaptive solution strategy. The developed diffusion simulator VLSIDIF-3 was designed to re-refine areas where difference of doping concentration between any of two nodes of each element is greater than tolerance and redo diffusion process until error is tolerable. Numerical experiment in low doping diffusion problem showed that this adaptive solution strategy is very efficient in both memory and time, and expected this scheme would be more powerful in complex diffusion model.

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Spin-On source에 의한 실리콘내의 불순물 확산 (Diffusion of Impurities Into Silicon by Spin-on Sources)

  • 김충기;정태원
    • 전기의세계
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    • 제27권6호
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    • pp.69-75
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    • 1978
  • Diffusion processes of boron, phosphorus, and arsenic into silicon have been investigated using a new diffusion source called "spin-on source". Diffusion coefficients of these impurities have been calculated from the experimental results and are compared with the published values. Reasonable agreements have been found between the calculated and the published values. From this study, it is concluded that the spin-on source can be used as the diffusion source for integrated circuit fabricaticon.ricaticon.

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ON THE REPRESENTATION OF PROBABILITY VECTOR WITH SPECIAL DIFFUSION OPERATOR USING THE MUTATION AND GENE CONVERSION RATE

  • Choi, Won
    • Korean Journal of Mathematics
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    • 제27권1호
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    • pp.1-8
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    • 2019
  • We will deal with an n locus model in which mutation and gene conversion are taken into consideration. Also random partitions of the number n determined by chromosomes with n loci should be investigated. The diffusion process describes the time evolution of distributions of the random partitions. In this paper, we find the probability of distribution of the diffusion process with special diffusion operator $L_1$ and we show that the average probability of genes at different loci on one chromosome can be described by the rate of gene frequency of mutation and gene conversion.

Midjourney와 Stable Diffusion을 이용한 AI 생성 이미지의 차이 비교 (Comparison of the Differences in AI-Generated Images Using Midjourney and Stable Diffusion)

  • 부이두엉화이린;이강희
    • 한국컴퓨터정보학회:학술대회논문집
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    • 한국컴퓨터정보학회 2023년도 제68차 하계학술대회논문집 31권2호
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    • pp.563-564
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    • 2023
  • Midjourney and Stable Diffusion are two popular AI-generated image programs nowadays. With AI's outstanding image-generation capabilities, everyone can create artistic paintings in just a few minutes. Therefore, "Comparison of differences between AI-generated images using Midjourney and Stable Diffusion" will help see each program's advantages and assist the users in identifying the tool suitable for their needs.

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시간의존성 염화물 확산계수와 압축강도 상관성에 대한 실험적 연구 (Experimental Study on the Relationship between Time-Dependent Chloride Diffusion Coefficient and Compressive Strength)

  • 이승훈;권성준
    • 콘크리트학회논문집
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    • 제24권6호
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    • pp.715-726
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    • 2012
  • 콘크리트의 대표적 물성치인 강도 및 염화물 확산계수는 재령에 따라 변화하며, 염화물 침투 해석시 이러한 영향들이 고려되고 있다. 이 연구는 다양한 혼화재료 (고로슬래그 미분말, 플라이애쉬, 실리카 퓸)을 포함하는 고성능콘크리트의 촉진염화물 확산계수, 겉보기 염화물 확산계수, 강도 특성을 재령에 따라 실험적으로 도출하고 그 상관성을 분석하는데 목적이 있다. 이를 위해 30개의 배합을 가지는 고성능 콘크리트가 제작되었고, 재령 28일, 91일, 180일, 270일에 대한 촉진확산계수를 실험적으로 도출하였으며, 또한 동일배합에 대하여 침지 6개월 이후의 겉보기 확산계수가 도출되었다. 재령에 대한 강도 특성을 평가하기 위해, 재령 7일, 28일, 91일, 180일에 대한 강도시험이 수행되었다. 시간 의존적인 촉진확산계수의 변화가 겉보기 확산계수 및 강도와 비교되었으며, 각각의 상관관계가 재령에 대하여 분석되었다. 이 연구를 통하여 겉보기 확산계수와 촉진확산계수는 재령에 큰 영향을 받지 않으면서 선형적인 상관성이 도출되었다. 또한 강도와 촉진확산계수 그리고 강도와 겉보기 확산계수에서도 재령에 큰 영향을 받지 않는 선형적인 관계가 도출되었다.