• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.50-50
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• 2011

The aluminum nitride films were prepared by RF magnetron sputtering using an AlN ceramic target. The crystallinity, grain size, Al-N bonding and thermal conductivity were investigated in dependence on the plasma power densities (4.93, 7.40, 9.87 W/$cm^2$) during sputtering. High thermal conductivity is important properties of A1N passivation layer for functioning properly in thermal inkjet printhead. The crytallinity, grain size, Al-N bonding formation and chemical composition were observed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS), respectively. The AlN thin film was changed from amorphous to crystalline as the power density was increased, and the largest grain size appeared at medium power density. The near stoichiometry Al-N bonding ratio was acquired at medium power density. So, we know that the AlN thin film had better thermal conductivity with crystalline phase and near stoichometry Al-N bonding ratio at 7.40 W/$cm^2$ power density.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2008년도 High Temperature Superconductivity Vol.XVIII
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• pp.39-39
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• 2008

• Journal of the Korean Wood Science and Technology
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• 제26권1호
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• pp.87-96
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• 1998

The bending performances were evaluated at the radiata pine plywood through veneer compositions encompassing veneer quality, ply-numbers and overlays of the high density- or medium density-phenol resin impregnated sheets (hereafter abbreviated as resin sheets) on the raw plywood. In addition, a prediction on the bending MOE of veneers and plywoods was carried out by the nondestructive testing with stresswave timer. The summarized results were as follows: I. Bending strength and bending MOE of resin sheets-overlaid plywoods in parallel surface grain direction through 5 and 7ply were increased by 13 to 45% and 17 to 34%, respectively. Resin sheets-overlay occurred an increasing effect of the strength efficiency i.e. strength perpendicular-to-grain direction versus that parallel-to-grain direction, showing the phenomenon that the plywood strength becomes greater at the perpendicular-to-grain direction of 7ply than at that of 5ply. Displacement at bending failure had a greater trend at 7ply than at 5ply, and was decreased by resin sheets-overlay. 2. After the nondestructive bending MOEs were measured for individual veneers, these veneers were rearranged in plywood-manufacture. In these plywoods, including resin sheets-overlay, the actual MOE was predictable with feasibility of $R^2$=0.53, and also the nondestructively-evaluated MOE was lower by 20% in raw plywood, and higher 20% in LVL than actual bending MOEs.

• Progress in Superconductivity
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• 제9권2호
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• pp.173-176
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• 2008

[ $MgB_2$ ] films grown by hybrid physical chemical vapor deposition under appropriate growth conditions commonly exhibit columnar grain structure. The grain boundaries between adjacent columnar grains have been reported to be good flux pinning centers. In this work, we measured the angular dependence of critical current density ($J_c$) and observed the enhanced flux pinning when an external magnetic field was aligned parallel to the columnar direction. This $J_c$ was almost comparable to the $J_c$ for intrinsic pinning case up to 1 T at low temperatures, indicating that grain boundary pinning is very effective. At high fields, however, $J_c$ decreased rapidly resulting from the fact that the density of flux pinning centers provided by grain boundaries was outnumbered by the flux density.

• Nuclear Engineering and Technology
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• 제29권3호
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• pp.196-200
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• 1997

The variation of sintered density and fain size in ex-AUC, ex-ADU and granulated ex-ADU UO$_2$ pellets in which 0.1~1.0wt% Nb$_2$O$_{5}$ were doped were examined. Pellets were sintered in an atmosphere of H$_2$ at 1$700^{\circ}C$ for 4h. All the specimens tested shooed more than 94% T.D.(Theoretical Density). Sintered density decreased with increasing the amount of Nb$_2$O$_{5}$. Powder types had little influence on the sintered density. Pore size distribution was shifted to the larger ones as Nb$_2$O$_{5}$ was added. The increase of total pore volume and grain growth due to the addition of Nb$_2$O$_{5}$ were thought to be the cause of the sintered density decrease. The largest grain size was seen in the 1. 0wt% Nb$_2$O$_{5}$ doped ex-AUC UO$_2$ pellets. Their average size was 13.9 ${\mu}{\textrm}{m}$.m}$.

• Corrosion Science and Technology
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• 제9권6호
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• pp.300-309
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• 2010

The influences of sensitization on localized corrosion resistance of 304 stainless steel, were investigated, using micro-dropletcell techniques. Micro-droplet cell allows one to align the micro-electrode to the desired spot of the working electrode and measure directly local current with the potentiodynamic polarization, linear polarization and a.c. impedance. Micro-electrochemical tests were carried out inside of the grain and on grain boundaries separately. It was found that sensitization decreased the pitting potential, increasing corrosion current density around grain boundaries. Galvanic current density was also measured between grain and grain boundaries.

• 한국세라믹학회지
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• 제39권11호
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• pp.1083-1089
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• 2002

알루미나 세라믹스에 MgO와 $TiO_2$를 각각 단독으로 첨가했을 때의 치밀화와 소결 거동을 수축률-소결 밀도 관계를 통해 비교 조사하였다. MgO가 첨가되었을 때는 소결 전과정을 통해 입성장은 억제되고 치밀화는 촉진되었으나, $TiO_2$가 첨가되었을 때는 입성장은 촉진된 반면 치밀화는 떨어졌다. 또한 입자 크기, 밀도, 수축률등을 통해 수축률-소결 밀도 관계를 구하여 최대 수축률을 나타내는 밀도값(Density of Maximum Shrinkage Rate:${\rho}$J.S.R)을 조사해 보았다. 이때 최대 수축률을 나타내는 밀도값보다 낮은 밀도를 보이는 영역에서는 치밀화가 입성장보다 우세하게 진행되었으며 최대 수축률을 나타내는 밀도값보다 높은 밀도의 영역에서는 입성장이 보다 우세하게 진행되는 것으로 추정하였다. 이때 최대 수축률을 나타내는 밀도값은 $TiO_2$가 첨가된 알루미나 < 순수 알루미나 < MgO가 첨가된 알루미나의 순서로 높은 값을 보였다.

• 한국작물학회지
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• 제67권3호
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• pp.155-163
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• 2022

The tillering potential of panicle number type (PNT) rice greatly varies with planting density. Moreover, grain filling and ripening differ depending on the panicle position, which may further affect rice grain quality. The present study evaluated the grain quality of PNT rice sparsely planted to reduce production costs. The physicochemical characteristics of starch from the grains of PNT type rice 'Ilpum' planted at different densities (37, 50, 60, and 80 plants/3.3 m²) and at different positions of panicles (upper or lower on the culm) were determined. Overall, as the planting density decreased, the number of panicles increased but the starch content decreased, which further reduced the 1,000-grain weight. In particular, at the lowest density (37 plants/3.3 m²), protein content increased but particle size, enthalpy, and relative crystallinity decreased. The effects were more pronounced at lower than at upper panicle positions. These findings indicate that tillering potential differs with planting density, ultimately affecting the palatability of rice grains. Based on these findings, we propose restricting rice transplantation to a planting density of ≤37 plants/3.3 m² to achieve the best quality of grains at lower costs and with less labor.

• Journal of the Korean Wood Science and Technology
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• 제47권1호
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• pp.40-50
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• 2019

The aim of this study was to investigate the effects of density, temperature, size, and grain direction on measurement of moisture contents (MC) of wood materials non-destructively. The MC of different sizes of solid wood, glulam, and CLT from larch (larix kaempferi, $560kg/m^3$) and pine (pinus koraiensis, $430kg/m^3$) were measured using the dielectric type and resistance type meters. The specimens were conditioned in the environmental chamber to be equilibrium moisture content (EMC) of 12 % and 19 %. When density setting in dielectric type meter was increased from $400kg/m^3$ to $600kg/m^3$, the MCs of specimen (S-L-100-E) were decreased from 13.4 % to 11.3 %. However, when wood group (WG) setting in resistance type meter was changed from WG1 to WG4, the measured MCs were increased from 9.2 % to 12.3 %. When temperature setting in resistance type meters was changed from 0 to $35^{\circ}C$, the MC was decreased from 17.0 % to 13.0 %. The MCs measured by dielectric type meter for larger specimens (S-L-100-E_11.3 %, G-L-240-E_11.7 % and C-L-120-E_12.8 %) were higher than those of small size specimens (S-L-30-E_8.7 %, G-L-150-E_10.3 %, and C-L-90-E_9.7 %). The MCs measured by resistance type meter for larger specimens (G-L-240-E_11.6 % and C-L-120-E_13.3 %) were also higher than those of small size specimens (G-L-150-E_10.4 %, and C-L-90-E_11.8 %). The resistance type meter was not affected by the grain direction but the dielectric type meter were affected by the grain direction. The MC measured by resistance type meter for G-L-120-E perpendicular to grain direction was 11.5 % and the measured MC parallel to grain direction was 11.3 %. The MC measured by dielectric type meter parallel to grain direction (12.1 %) was higher than that measured perpendicular to grain direction (10.7 %).

• 한국재료학회지
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• 제30권2호
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• pp.57-60
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• 2020

Titanium aluminides have attracted special interest as light-weight/high-temperature materials for structural applications. The major problem limiting practical use of these compounds is their poor ductility and formability. The powder metallurgy processing route has been an attractive alternative for such materials. A mixture of Ti and Al elemental powders was fabricated to a mechanical alloying process. The processed powder was hot pressed in a vacuum, and a fully densified compact with ultra-fine grain structure consisting of Ti₃Al intermetallic compound was obtained. During the compressive deformation of the compact at 1173 K, typical dynamic recrystallization (DR), which introduces a certain extent of grain refinement, was observed. The compact had high density and consisted of an ultra-fine equiaxial grain structure. Average grain diameter was 1.5 ㎛. Typical TEM micrographs depicting the internal structure of the specimen deformed to 0.09 true strain are provided, in which it can be seen that many small recrystallized grains having no apparent dislocation structure are generated at grain boundaries where well-developed dislocations with high density are observed in the neighboring grains. The compact showed a large m-value such as 0.44 at 1173 K. Moreover, the grain structure remained equiaxed during deformation at this temperature. Therefore, the compressive deformation of the compact was presumed to progress by superplastic flow, primarily controlled by DR.