• Title/Summary/Keyword: Diffusion Direction

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A New Image Enhancement Algorithm Based on Bidirectional Diffusion

  • Wang, Zhonghua;Huang, Xiaoming;Huang, Faliang
    • Journal of Information Processing Systems
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    • v.16 no.1
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    • pp.49-60
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    • 2020
  • To solve the edge ringing or block effect caused by the partial differential diffusion in image enhancement domain, a new image enhancement algorithm based on bidirectional diffusion, which smooths the flat region or isolated noise region and sharpens the edge region in different types of defect images on aviation composites, is presented. Taking the image pixel's neighborhood intensity and spatial characteristics as the attribute descriptor, the presented bidirectional diffusion model adaptively chooses different diffusion criteria in different defect image regions, which are elaborated are as follows. The forward diffusion is adopted to denoise along the pixel's gradient direction and edge direction in the pixel's smoothing area while the backward diffusion is used to sharpen along the pixel's gradient direction and the forward diffusion is used to smooth along the pixel's edge direction in the pixel's edge region. The comparison experiments were implemented in the delamination, inclusion, channel, shrinkage, blowhole and crack defect images, and the comparison results indicate that our algorithm not only preserves the image feature better but also improves the image contrast more obviously.

Thermal Environment Analysis by the Diffusion Direction with Ceiling Type Air Conditioner of the Classroom (학교 교실의 천장형 에어컨 토출각도에 따른 온열환경 해석)

  • AHN, Chul-Lin;KIM, Dong-Gyue;KUM, Jong-Soo;PARK, Hee-Ouk;CHUNG, Yong-Hyun
    • Journal of Fisheries and Marine Sciences Education
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    • v.17 no.2
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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.

Determination of Diffusion Coefficients of Boron from Borate Rods in Wood Using Boltzmann's Transformation

  • Ra, Jong-Bum
    • Journal of the Korean Wood Science and Technology
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    • v.31 no.3
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    • pp.24-29
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    • 2003
  • This research was performed to investigate the diffusivity of borate rods in radiata pine (Pinus radiata D. Don) conditioned to 40 percent moisture content (MC). The deepest penetration of boron were observed in the longitudinal direction, followed by the radial and the tangential directions. The boron loading on the wood face adjacent to the borate rod tended to increase with diffusion time in all directions. To mathematically quantify boron diffusion, the diffusion coefficient of boron was determined using Boltzmann's transformation by assuming that it was a function of concentration only. The values of the longitudinal diffusion coefficients were between 1.3×10-8 cm2/sec and 9.2×10-8 cm2/sec. The radial diffusion coefficients were between 1.4×10-8 cm2/sec and 9.5×10-8 cm2/sec, and the tangential diffusion coefficients were between 5.2×10-9 cm2/sec and 1.3×10-8 cm2/sec. The differences of diffusion coefficients between the longitudinal direction and the radial direction were slight, although their concentration profiles were markedly different. This indicates that the amount of boron loading on the wood face adjacent the borate rod is one of the most important factor for boron penetration in wood with low MC.

The Diffusion of Boron from Borate Rod through Pinus densiflora and Pinus koraiensis (소나무와 잣나무에서 붕산염 막대로부터 붕소의 확산)

  • Oh, Choong-Sup;Kim, Jae-Jin;Kim, Gyu-Hyeok
    • Journal of Conservation Science
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    • v.7 no.2
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    • pp.60-67
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    • 1998
  • The effects of moisture content (MC) and diffusion period on the diffusion of boron from borate rod through Pinus densiflora and P. koraiensis were investigated as a preliminary research of integrated remedial treatment for heritage wooden structures using borate rod. After equilibrating MCs of samples (15, 25, and 40%), borate rod (1,000 mg) was inserted into the sample, and stored for diffusion of boron at room temperatures ($23^{\circ}C$) for 2, 4, 8, and 12 weeks. Wafers were serially cut at constant intervals from rod treatment point and the boron penetration through longitudinal and transverse direction was measured by staining with boron indicator. For boron diffusion, MC above fiber saturation point was needed, and the diffusion rates increased with time. The fastest rates of diffusion were observed in longitudinal direction, followed by the radial and then the tangential direction. The rates of diffusion in all directions were the fastest in P. koraiensis. In P. densiflora, the diffusion rates through heartwood was faster than that in sapwood in longitudinal direction and vice versa in transverse direction. Based on the best result of this study, optimal space between rod insertion points could be recommended as follows; approximately 120 mm for P. koraiensis and heartwood of P. densiflora, 60 mm for sapwood of P. densiflora in longitudinal direction, and approximately 30 mm for all species tested in transverse direction. However, the effect of rod size and long-term exposure for diffusion on boron movement should be fully investigated for the accurate evaluation of optimal space between rod holes.

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Burke-Schumann analysis of silica formation by hydrolysis in an external chemical vapor deposition process (외부 화학증착 공정에서의 가수분해반응으로 인한 실리카 생성에 대한 버크-슈만 해석)

  • Song, Chang-Geol;Hwang, Jeong-Ho
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.20 no.5
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    • pp.1671-1678
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    • 1996
  • In external chemical vapor deposition processes including VAD and OVD the distribution of flame-synthesized silica particles is determined by heat and mass transfer limitations to particle formation. Combustion gas flow velocities are such that the particle diffusion time scale is longer than that of gas flow convection in the zone of particle formation. The consequence of these effects is that the particles formed tend to remain along straight smooth flow stream lines. Silica particles are formed due to oxidation and hydrolysis. In the hydrolysis, the particles are formed in diffuse bands and particle formation thus requires the diffusion of SiCl$\_$4/ toward CH$\_$4//O$\_$2/ combustion zone to react with H$\_$2/O diffusing away from these same zones on the torch face. The conversion kinetics of hydrolysis is fast compared to diffusion and the rate of conversion is thus diffusion-limited. In the language of combustion, the hydrolysis occurs as a Burke-Schumann process. In selected conditions, reaction zone shape and temperature distributions predicted by the Burke-Schumann analysis are introduced and compared with experimental data available. The calculated centerline temperatures inside the reaction zone agree well with the data, but the calculated values outside the reaction zone are a little higher than the data since the analysis does not consider diffusion in the axial direction and mixing of the combustion products with ambient air. The temperatures along the radial direction agree with the data near the centerline, but gradually diverge from the data as the distance is away from the centerline. This is caused by the convection in the radial direction, which is not considered in the analysis. Spatial distribution of silica particles are affected by convection and diffusion, resulting in a Gaussian form in the radial direction.

Characteristics of Proton-Diffused $LiNbO_3$ Optical Waveguides with Self-Aligned $SiO_2$-Cladding (자기정렬된 $SiO_2$ 클래딩 구조를 갖는 양자확산 $LiNbO_3$ 광도파로의 특성)

  • Son, Yung-Sung;Lee, Hyung-Jae;Shin, Sang-Yung
    • Proceedings of the KIEE Conference
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    • 1989.07a
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    • pp.655-658
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    • 1989
  • The characteristics of proton-diffused $LiNbO_3$ optical waveguides with self-aligned $SiO_2$-cladding are reported. When the proton diffusion occurs, the $SiO_2$-cladding limits the lateral diffusion of protons by out-diffusion of protons in unclad region. Proton indiffusion in depth direction is promoted by inhibition of out-diffusion in clad region. Consequently, the mode profile in depth direction can be nealy symmetric. The extent of the proton exchange was observed by measuring the infrared absorption peak at about $3500cm^{-1}$. It is confirmed that proton diffusion with $SiO_2$-cladding has structural excellency.

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Bond Strength of Steel honeycomb Structure (철강 하니콤구조의 접합강도)

  • Song, Keun;Hong, Young Hwan
    • Journal of the Korean Society for Heat Treatment
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    • v.16 no.4
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    • pp.197-204
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    • 2003
  • Honeycomb structure has been fabricated by brazing method using 0.1 wt%C and 1.0wt%C carbon steel core and STS304 stainless steel face sheet. Core shear strength ratio in W and L directions was 1:1.03 in 7 mm cell size, whereas 1:1.45 in 4 mm cell size. Flexural strength on face sheet was 166.4 MPa (0.1 wt%C, W direction), 171.1 MPa (0.1 wt%C, L direction), and 120.2 MPa (1.0 wt%C, W direction) in 7 mm cell size. And in 4mm cell size specimen, it was 169.2 MPa (0.1 wt%C, W direction), 224.2 MPa (0.1 wt%C, L direction). This means that flexural strength of 0.1 wt%C core material was higher than that of 1.0wt%C core material, which was contrary to expectation. SEM and EDS analysis represented that grain boundary diffusion had occurred in0.1 wt%C core, but no grain boundary diffusion in 1.0 wt%C core. And corrugated surface of 0.1 wt%C core was flat, whereas that of 1.0 wt%C core was not flat. As a result, contact area between two 1.0 wt%C cores was much less than that of 0.1 wt% cores, It is thought to be main reason for lower flexural strength of 1.0 wt%C core.

MEDICAL IMAGE ANALYSIS USING HIGH ANGULAR RESOLUTION DIFFUSION IMAGING OF SIXTH ORDER TENSOR

  • K.S. DEEPAK;S.T. AVEESH
    • Journal of applied mathematics & informatics
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    • v.41 no.3
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    • pp.603-613
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    • 2023
  • In this paper, the concept of geodesic centered tractography is explored for diffusion tensor imaging (DTI). In DTI, where geodesics has been tracked and the inverse of the fourth-order diffusion tensor is inured to determine the diversity. Specifically, we investigated geodesic tractography technique for High Angular Resolution Diffusion Imaging (HARDI). Riemannian geometry can be extended to a direction-dependent metric using Finsler geometry. Euler Lagrange geodesic calculations have been derived by Finsler geometry, which is expressed as HARDI in sixth order tensor.

Computer Simulation on the Thermal Environment by the Diffusion temperature and Diffusion Angle of Ceiling Type Air Conditioner in Classroom (교실에서의 천장형 냉난방기의 취출온도 및 취출각도에 따른 열환경 시뮬레이션)

  • Park, Hyo-Soon;Park, Seung-Ik;Lee, Sang-Hyeok;Lee, Kam-Gyu
    • The Journal of Sustainable Design and Educational Environment Research
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    • v.4 no.4
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    • pp.1-18
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    • 2004
  • Research has been carried out to study thermal environment in a classroom under three kinds of air diffusion temperature and six kinds of air diffusion direction for ceiling type air conditioner. The velocity and temperature distributions of air in the room calculated by 3-dimensional numerical method(PHOENICS), This present study was also conducted to calculate the Air Diffusion Performance Index(ADPI) for cooling conditions and Predicted Percentage of Dissatisfied(PPD) for heating conditions. This analysis shows that the optimum angle of ceiling type air conditioner's diffusion is $15{\sim}30^{\circ}$ for cooling mode and about $15{\sim}45^{\circ}$ for heating mode in these calculating conditions. And also analysis has been carried out to evaluate thermal comfort of vertical and horizontal cross section of classroom.

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Carbon and Cobalt Diffusion in Liquid Phase Sintering of WC-Co with Gradient Composition

  • Park, Dong-Kyu;Kim, Ki-Won;Jung, Woo-Hyun
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.635-636
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    • 2006
  • In this study, the diffusion behaviors of C and Co in liquid phase sintering of WC-Co system were investigated whether these two components diffused in the same direction in case of having opposite gradient each other with not being $\eta$ phase. The green compacts with controlled compositions in not being of $\eta$ phase and gradient composition which one is WC-5Co-1.2%C, the other is WC-XCo-0.2%C (where X = 5, 10, 15, 20, 25) were sintered at $1350^{\circ}C$ and $1400^{\circ}C$ and then the diffusion behaviors of C and Co were investigated by analyses of compositional change, also determined for microstructure and microhardness. Also, same testing was carried out on the specimens with dual layers sintered in upright and reverse positions to evaluate the effect of gravity on the diffusion in liquid Co. From the results of this study, we can find the fact that the direction of diffusion for C and Co in WC-Co system during liquid phase sintering was different and the effect of gravity for the liquid was insignificant. Also other physical properties were changed on the diffusion of elements.

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