• Journal of Conservation Science
• /
• v.7 no.2
• /
• pp.60-67
• /
• 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.

• Journal of Sensor Science and Technology
• /
• v.4 no.4
• /
• pp.70-74
• /
• 1995

We have observed anisotropic anodisation process for porous silicon formation. The starting material was (100) silicon $n/n^{+}/n$ wafer structured by $n^{+}$-diffusion on n-type substrate and by subsequent n-epitaxial growth. After the top n-silicon epitaxial layer was etched to open the porous silicon layer(PSL) anodisation window, anodisation takes place only to $n^{+}$-buried layer. The process of porous silicon formation on (100) sample was anisotropic, which was evident from that the shapes of the reacted porous silicon layer was all squarelike regardless of the shapes of reaction windows. The experimental results show that the PSL anodisation process does not depend on chemical reaction but does on electrical conduction property, which is hole mobility depending on the crystal direction.

• Journal of the Korean Magnetics Society
• /
• v.3 no.4
• /
• pp.298-304
• /
• 1993

The effects of the substrate temperature and the Pd underlayer on the structure and the magnetic properties of Pd/Co multilayer films prepared by the thermal evaporation were studied. As the substrate temperature increases up to $150^{\circ}C$, the crystallinity of sublayers, (111) texture and the interface sharpness of Pd/Co multilayers were improved due to the enhanced mobility of adatoms. As results of that, the perpendicular and surface anisotropy energies were increased but the coercivity was decreased because the pinning sites of domain wall decreased due to the grain growth. The grain size of the multilayers increased with Pd underlyer thickness. Thermal degradation was enhanced at above $200^{\circ}C$ due to interdiffusion at the Pd/Co interface. The intensity of the main diffraction peak rapidly decayed in the initial stage of aging and then decreased slowly. The rapid change of the intensity in the initial stage was speculated to be due to the structural relaxation phenomena and the later stage change was due to the interdiffusion. The activation energy for the interdiffusion in Pd4/Co1 multilayers was 14.9 KCal/mole.K.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.21 no.1
• /
• pp.45-50
• /
• 1984

V-groove N+P solar cell is fabricated by thermal diffusion in silicon wafer with (100) crystal structure. To form the V-grooves in (100) silicon surface, a mixture of etylen-diamine, water, pyrocathecol is used as the etchant of anisotropic etching. Under light intensity of 100mW/$\textrm{cm}^2$, the efficiency of the V-groove solar cell is 2.5-3.5% greater than the conventional N+P solar cell and 0.4-0.6% greater than the texturized one.

• Korean Journal of Materials Research
• /
• v.11 no.7
• /
• pp.609-614
• /
• 2001

This study was carried out to obtain a basic data on the production of the Nd-Fe-B system rare earth anisotropic bonded magnet by R-D & HDDR process. The reduction reaction of Nd$_2$O$_3$by metallic Ca and the diffusion reaction of Nd into Fe-B alloy powder were investigated for the production the Nd-Fe-B alloy powder. We concluded that a proper quantity of metallic Ca was about 1.3 times of theoretical equivalent from the yields of Nd and B after the R-D reaction at 100$0^{\circ}C$ for 1h. In the XRD analysis the diffusion reaction of Nd into the center of Fe-B alloy powder for the completed homogenization was required through about 45min at 110$0^{\circ}C$ for the R-D reaction, and also the maximum efficiency on the yield of Nd was obtained with such a condition. Residual Ca and oxygen contents of the final powder sample after washing were detected in 0.17wt% and 0.42wt% by ICP and oxygen analyzer, respectively.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.4
• /
• pp.347-355
• /
• 2014

Thermal problems that are directly related to the lifetime of an electronic device are becoming increasingly important owing to the miniaturization of electronic devices. To solve thermal problems, it is essential to study thermal stability through thermal diffusion and insulation. A honeycomb sandwich plate has anisotropic thermal conductivity. To analyze the thermal deformation and temperature distribution of a system that employs a honeycomb sandwich plate, the thermal and elastic properties need to be determined. In this study, the thermal and elastic properties of a honeycomb sandwich plate, such as thermal conductivity, coefficient of thermal expansion, elastic modulus, Poisson's ratio, and shear modulus, are predicted. The properties of a honeycomb sandwich plate vary according to the hexagon size, thickness, and material properties.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.5 no.2
• /
• pp.157-165
• /
• 2009

Existing methods for image segmentation using diffusion can't preserve contour information, or noises with high gradients become more salient as the umber of times of the diffusion increases, resulting in over-segmentation when applied to watershed. This thesis proposes a method for image segmentation by applying morphology operation together with robust anisotropic diffusion. For an input image, transformed into LUV color space, closing by reconstruction and anisotropic diffusion are applied to obtain a simplified image which preserves contour information with noises removed. With gradients computed from this simplifed images, watershed algorithm is applied. Experiments show that color images are segmented very effectively without over-segmentation.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.8 no.5
• /
• pp.462-468
• /
• 1984

The variation of thermal diffusivity with respect to rolling reduction is experimentally determined by flash technique. Copper alloy is used as an experimental and specimens are cut from the slab produced by rolling process with different percent reduction in thickness along the rolling direction and with 30.deg. 60.deg. and 90.deg. angle to the rolling direction. It is found that thermal diffusivity is slightly decreased as rolling reduction increased, and it has tendency that thermal diffusivity is increased slightly as its angle approached to 90.deg. at same rolling reduction.

• Journal of Biomedical Engineering Research
• /
• v.15 no.4
• /
• pp.401-406
• /
• 1994

A magnetic resonance neurography technique for exclusive imaging of nerve networks is proposed. In the proposed technique, the anisotropy of diffusion coefficients of the molecules inside nerve cells was utilized to effectively suppress the magnetic resonance signal radiating from ones other than nerve tissues. Two images were obtained with diffusionweighting magnetic field gradients applied in the parallel and perpendicular directions with respect to the nerve orientation. One image was then subtract- ted from the other to form the neurogram. Experimentally obtained neurograms of the squld are presented.

• Economic and Environmental Geology
• /
• v.40 no.6
• /
• pp.761-769
• /
• 2007

We made 712 thermal property measurements on igneous, metamorphic and sedimentary rock samples from Gyeonggi-do, Gangwon-do and Chungchung-do, Korea. The average thermal conductivities of igneous, metamorphic and sedimentary rocks are 3.58W/m-K, 4.16W/m-K and 4.53W/m-K, respectively. Thermal conductivity of granite and gneiss are 2.13-5.87W/m-K and 2.26-6.67W/m-K, with average values of 3.57W/m-K and 3.945W/m-K, respectively. The average of thermal diffusivities are $1.43mm^2/sec\;and\;1.55mm^2/sec$, respectively; the average of specific heat values are 0.914J/gK, 0.912J/gK for granite and gneiss samples, respectively. The thermal conductivity of a rock type generally have a wide range because it depends on various factors such as dominant mineral phase, micro-structure, anisotropy, and so on.