• 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.

• 한국콘텐츠학회논문지
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• 제8권11호
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• pp.1-9
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• 2008

현재 멀티미디어 기술의 발달로 인하여 영상의 전처리 및 후처리 과정을 이용한 수정 작업으로 고품질의 영상 표현 및 다양한 영상 처리가 가능하다. 영상 처리 기법 중에서 이방성 확산의 경우 영상의 스페클 노이즈 제거, 에지 검출, 영상 분할 등에 응용할 수 있는 효과적인 확산 필터링으로 활용되고 있다. 하지만 전통적인 이방성 확산은 십자형 커널을 기반으로 하고 있기 때문에 확산 필터링을 반복 적용하면 영상의 에지가 수평 및 수직 방향으로 집중되는 문제점이 있다. 본 논문에서는 기존의 십자형 커널 기반의 이방성 확산 문제점을 해결하기 위하여 기울기의 방향성에 기반한 새로운 이방성 확산 방식을 제안한다. 제안된 방식은 십자형 커널을 확장하여 대각선 방향 정보를 포함한 8방향의 정방형 커널을 기반으로 작은 기울기를 갖는 방향으로 이방성 확산을 적용한다. 제안된 방식의 실험 결과 에지가 수평 및 수직 방향으로 집중되는 문제점을 해결하면서 임펄스성 노이즈를 제거하여 고품질의 영상을 획득할 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 제5회 영호남 학술대회 논문집
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• pp.59-62
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• 2003

Our Zn diffusion into n-type $GaAs_{0.60}P_{0.40}$ used ampoule-tube method to increase IV. N-type epitaxial wafers were preferred by $H_2SO_4$-based pre-treatment. $SiO_2$ thin film was deposited by PECVD for some wafers. Diffusion times and diffusion temperatures respectability are 1, 2, 3 hr and 775, $805^{\circ}C$. LED chips were fabricated by the diffused wafers at Fab. The peak wavelength of all chips showed about 625~650 nm and red color. The highest IV is about 270 mcd at the diffusion condition of $775^{\circ}C$, 3h for the wafers which didn't deposit $SiO_2$ thin films. Also, the longer diffusion time is the higher IV for the wafers which deposit $SiO_2$ thin films.

• Nuclear Engineering and Technology
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• 제16권1호
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• pp.21-28
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• 1984

수치확산을 포함한 truncation오차의 줄임은 수치해석의 중요한 과제가 되어왔다. Stream line방법이 교차수치 확산과 비확산형의 truncation 오차를 제거하기 위하여 고안되었다. 또한, stream line방법과 유한 차분법이 합쳐진 2단계 stream line방법이 비압축성 난류유동의 지배 방정식을 풀기 위하여 고안되었다. 이 방법은 유한 차분법과 비교되었으며, 두 방법 모두 실험자료와 비교되었다. 그리고, 두 방법의 truncation 오차를 비교하기 위하여 truncation 오차 분석이 행해졌다

• Fisheries and Aquatic Sciences
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• 제7권2호
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• pp.90-95
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• 2004

An analytical model for predicting the convection-diffusion of solute dumped in a homogeneous open sea of constant water depth has been developed in a time-integral form. The model incorporates spatially uniform, uni-directional, mean and oscillatory currents for horizontal convection, the settling velocity for the vertical convection, and the anisotropic turbulent diffusion. Two transformations were introduced to reduce the convection-diffusion equation to the Fickian type diffusion equation, and then the Galerkin method was then applied via the expansion of eigenfunctions over the water column derived from the Sturm-Liouville problem. A series of calculations has been performed to demonstrate the applicability of the model.

• 한국해양공학회지
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• 제16권5호
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• pp.41-48
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• 2002

Numerical experiments are conducted using a three-dimensional baroclinic equation model and a Lagrangian method for clarifying the effect of th settling velocity on the suspended solids diffusion caused by the dredging and the reclamination works. Diffusion characteristics of the neutral particles and the weighting particles is experimented by the Lagrangian particles trajectory model, The results show that the diffusion characteristics of the suspended solids is effected by the settling velocity classified by the particles size in the density layered semi-closed bay. To estimate exactly the diffusion characteristics of the suspended solids and the contaminant with weight the three-dimensional baroclinic equation model and the three-dimensional Lagrangian particles trajectory model considering the settling velocity of the particle in the density layered semi-closed bay must be used.

• 한국결정성장학회지
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• 제14권2호
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• pp.58-62
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• 2004

The shape evolution of the interface void of copper metallization for intergrated circuits under electromigration stress is modeled. A 2-dimensional finite-difference numerical method is employed for computing time evolution of the void shape driven by surface diffusion, and the electrostatic problem is solved by boundary element method. When the diffusion coefficient is isotropic, the numerical results agree well with the known case of wedge-shape void evolution. The numerical results for the anisotropic diffusion coefficient show that the initially circular void evolves to become a fatal slitlike shape when the electron wind force is large, while the shape becomes non-fatal and circular as the electron wind force decreases. The results indicate that the open circuit failure caused by slit-like void shape is far less probable to be observed for copper metallization under a normal electromigration stress condition.

• 한국통신학회논문지
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• 제29권1C호
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• pp.50-58
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• 2004

본 논문은 수정된 이방성 확산 펄터를 이용한 영상 개선 방법을 제안하였다. 이를 위하여 최소 신뢰 스케일을 기반으로 하는 센서 잡음 추정과 스케일 스페이스 방법을 도입하였다. 이때 이방성 필터는 구해진 임계값 함수와 국부 기울기에 의해 수정되었다. 모의 실험을 통해 제안한 방법이 평탄 영역에서의 잡음을 거의 증폭시키지 않으면서도 뛰어난 에지 향상을 보임을 증명할 수 있었다.

• 수산해양교육연구
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• 제17권2호
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• pp.145-154
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• 2005

It is necessary to develop new air-conditioning method which can be satisfied individual separated space and request of occupants. The indoor thermal environment and flow field are investigated both experimentally and numerically. This study concentrated on analysis of indoor thermal environment by diffusion direction of ceiling type air conditioner of the classroom. The velocity and temperature distribution of air in the room calculated by 3-dimensional method, which include the effect of insulation of the building and outdoor state. This analysis shows that optimum diffusion direction is $30^{\circ}$ to increase thermal comfort in winter and optimum diffusion direction is $15^{\circ}$ to increase thermal comfort in summer.

• Computers and Concrete
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• 제10권3호
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• pp.219-229
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• 2012

Carbonation is a widespread degradation of concrete and may be coupled with more severe degradations. An experimental investigation was carried out to study the effect of carbonation on chloride ion diffusion of concrete. The characteristic of concrete after carbonation was measured, such as carbonation depth, strength and pore structure. Results indicated that carbonation depth has a good linear relation with square root of carbonate time, and carbonation can improve compressive strength, but lower flexural strength. Results about pore structure of concrete before and after carbonation have shown that carbonation could cause a redistribution of the pore sizes and increase the proportion of small pores. It also can decrease porosities, most probable pore size and average pore diameters. Chloride ion diffusion of concrete after carbonation was studied through natural diffusion method and steady state migration testing method respectively. It is supposed that the chloride ion concentration of carbonation region is higher than that of the sound region because of the separation of fixed salts, and chloride ion diffusion coefficient was increased due to carbonation action evidently.