• Journal of Welding and Joining
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• v.19 no.3
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• pp.325-333
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• 2001

The effect of base metal grain size on isothermal solidification behavior of Ni-base superalloy, CMSX-2 during transient liquid phase (TLP) bonding was investigated employing MBF-80 insert metal. TLP-bonding of single crystal. coarse-grained and fine-grained CMSX-2 was carried out at 1373∼1548k for various holding time in vacuum. The eutectic width diminished linearly with the square root of holding time during isothermal solidification process for single crystal, coarse-grained and fine-grained base metals. The completion time for isothermal solidification decreased in the order ; single crystal, coarse-grained and fine-grained base metals. The difference of isothermal solidification rates produced when bonding the different base metals could be explained quantitatively by the effect of base metal grain boundaries on the apparent average diffusion coefficient of boron in CMSX-2.

• Bulletin of the Korean Chemical Society
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• v.15 no.12
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• pp.1080-1084
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• 1994

Asymmetric inducing effects of substituents attached at nitrogen, the 5-position and boron in oxazaborolidine rings on asymmetric borane reduction of ketones were investigated. Thus, the effect of N-substituents examined with the oxazaborolidines prepared from (lR,2S)-N-alkyl norephedrine derivatives showed the remarkable decrease of enantioselectivities of the product alcohols by the variation of the steric size of alkyl groups on nitrogen from Me${\leftrightarro}$n-Bu(${\simeq}$Bn)${\leftrightarro}$ neopentyl${\leftrightarro}$i-Pr, such as 83${\%}$ ee with 5b, 22${\%}$ ee with 5c, 23${\%}$ ee with 5f, 16${\%}$ ee with 5e, and 3${\%}$ ee with 5d for the reduction of acetophenone. The presence of diphenyl groups at the 5-position enhanced the enantioselectivities dramatically. The effect of B-alkyl substituents in the oxazaborolidines derived from (lR,2S)-ephedrine showed that the enantioselectivities of product alcohols decreased gradually when the substituents were changed from hydrogen to steric bulky groups such as methyl, n-butyl, thexyl and phenyl.

• Journal of The Korean Society of Grassland and Forage Science
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• v.23 no.2
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• pp.81-90
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• 2003

This pot experiment was conducted to find out the effects of boron application(B$_{0}$; 0.0, B$_1$; 0.2, $B_2$;2.0, $B_3$;6.0, $B_3$;6.0, $B_4$;15.0me B/pot) on the forage performance in the pure and mixed swards of orchardgrass and white clover. This 1st part was concerned with the changes in the growth, flowers and flower buds, and roots/nodules of forages. The results obtained are summarized as follows: 1. At the $B_3$ and $B_4$ treatments, the B toxicity was more seriously in white clover than in orchardgrass in the first half of cutting orders, and reduced in the latter half. In white clover, it was more worsened in a mixture than in a pure culture. It was somewhat reduced at the best growth stage of each forage. 2. In orchardgrass, the B toxicity($B_3$,$ B_4$) showed the chlorosis on leaf tips, shallow leaf, little tillers, and weak stems. Whereas it showed the chlorosis/necrosis on old leaf edge, little and weak stolons in white clover. 3. Comparing with the B deficiency($B_{0}$ , $B_1$) and toxicity($B_3$, $B_4$), the optimum B application($B_2$) influenced markedly good growth of shoot, root, nodule, and flower (flower number, blooming period, early full flower) in white clover. 4. Comparing with orchardgrass, white clover was greatly influenced by the boron application. However, this responses of white clover to boron were reduced in a grass-clover mixture with additional fertilization. It was recognized that the good forage performance in a grass-clover mixture could be regulated by the adequate applications of boron and additional fertilizers.s.

• Journal of the Korean institute of surface engineering
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• v.28 no.2
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• pp.110-118
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• 1995

The effect of reductants (Ti, Si, Al, Mn, Fe) addition into molten Borax has been studied on oxidation resistance and the growth of boronized layer formed during electro-boronizing on the substrate such as carbon steel and STS 430. Experiments have been carried out at the current density of 0.5 A/$\cm^2$ and in temperature range of 600~$1000^{\circ}C$ for 1~5 hours. The penetrated depth of the boron increased with addition of reductants (Ti, Si, Al) and decreased with addition of Mn and Fe. But excessive addition of reductants inhibited the boronizing due to an increase in viscosity of electrolyte. Oxidation resistance of the boronized carbon steel was improved but that of the boronized STS 430 decreased.

• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.886-890
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• 2014

The properties of magnetic material of Nd-Fe-B are highly affected by various factors such as particle size, magnetic anisotropy, phase purity and crystal structure. Incorporation of excess neodymium was carried out in various percentages so that it will adjust the proportion of neodymium in the host crystal after reduction treatment and finally help to improve magnetic property of a material. The interdiffusion of Nd-Fe and boron was studied for various compositions and their effect on magnetic property was understood with theoretical concepts. The factors such as amount of hard and soft phase in the reduction treated product is also responsible for the possible exchange coupling between hard and soft phase magnets for better magnetic properties.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.3
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• pp.181-187
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• 1998

The ionization energy and degree of ionization for p-type $Si_{1-x}Ge_x$ with boron doping are calculated taking into account the screening and broadening effects. The drift and Hall mobilities are then calculated using the relaxation time approximation and compared with the previously reported measurement data for relaxed and strained $Si_{1-x}Ge_x$ alloys to estimate the alloy scattering potential. From a fit, the alloy scattering potential is found to be 0.5 eV. The in-plane drift mobility for p-type strained $Si_{1-x}Ge_x$ grown on (001) Si substrate is approximately 1+$10x^2$ times higher than that for bulk Si in the high doping range.

• Journal of the Korean institute of surface engineering
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• v.32 no.2
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• pp.172-181
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• 1999

The effect of the DMAB concentration, temperature, deposition time, and stabilizer concentration on the precipitation reaction of the electroless nickel plating using dimethylamine borane (DMAB) as reducing agent was investigated to by the weight gain and electrochemical method. The deposition rate was dependent with DMAB concentration. The polarization resistance of the precipitation reaction was reduced with DMAB concentration. The precipitation reaction rate of Ni-B deposits was controlled by the oxidation rate of DMAB as the source of electron. The boron content of the deposit was constant at about 5.5wt%, even when DMAB concentration in the solution was increased. The effect of temperature and stabilizer ($Pb(NO_3)_2$) concentration on deposition rate was shown to have co-dependent behaviors.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1138-1139
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• 2006

The present study has shown that the effect of boron and phosphorus in Ni-Cr-Si-X alloy to interfacial reactions and bonding strength of diamond-steel substrate, and the influence of various construction parameters on the formation of the topography of the tool. And these factors are required to making a good brazed tool. The microstructures and phase change of the brazed region were analyzed into SEM, EDS. According to the electron probe microanalysis, while brazing, the chromium present in the brazing alloy segregated preferentially to the surface of the diamond to form a chromium rich reaction product, which was readily wetted by the alloy.

• Korean Journal of Soil Science and Fertilizer
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• v.4 no.2
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• pp.143-147
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• 1971

Field experiments were carried out to determine the effect of B on rape with application of lime and compost in sandy upland soil and in clayey paddy soil. The plant samples from each treatment at flowering stage were analyzed to interpret the yield response. The effect of B was very significant in both soils, but more marked in sandy upland soil. The application of 20kg/ha borax appears to increase upto the possible level that can be achieved by B application. Application of 40kg/ha borax did not give any further additional response. In acidic paddy soil (pH 5.4), the effect of B was fully exhibited only with liming. Liming neither intensified the B deficiency nor reduced the B content in the plant tissue, but rather promoted the growth of rape plant. There was highly significant negative correlation between Ca/B ratio and seed yield ($r=-0.74^{**}$), but it was very difficult to draw a line between normal and deficient Ca/B ratio. It is very interesting that boron application significantly increased the Ca uptake in no lime treatment. Application of compost was generally inffective and did not affect the B supply to the plant. However, it appears to increase K uptake slightly and give a little favorable effect on growth of plant.

• Radiation Oncology Journal
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• v.19 no.1
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• pp.66-73
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• 2001

Purpose : For the research of Boron Neutron Capture Therapy (BNCT), fast neutrons generated from the MC-50 cyclotron with maximum energy of 34.4 MeV in Korea Cancer Center Hospital were moderated by 70 cm paraffin and then the dose characteristics were investigated. Using these results, we hope to establish the protocol about dose measurement of epi-thermal neutron, to make a basis of dose characteristic of epi-thermal neutron emitted from nuclear reactor, and to find feasibility about accelerator-based BNCT. Method and Materials : For measuring the absorbed dose and dose distribution of fast neutron beams, we used Unidos 10005 (PTW, Germany) electrometer and IC-17 (Far West, USA), IC-18, ElC-1 ion chambers manufactured by A-150 plastic and used IC-l7M ion chamber manufactured by magnesium for gamma dose. There chambers were flushed with tissue equivalent gas and argon gas and then the flow rate was S co per minute. Using Monte Carlo N-Particle (MCNP) code, transport program in mixed field with neutron, photon, electron, two dimensional dose and energy fluence distribution was calculated and there results were compared with measured results. Results : The absorbed dose of fast neutron beams was $6.47\times10^{-3}$ cGy per 1 MU at the 4 cm depth of the water phantom, which is assumed to be effective depth for BNCT. The magnitude of gamma contamination intermingled with fast neutron beams was $65.2{\pm}0.9\%$ at the same depth. In the dose distribution according to the depth of water, the neutron dose decreased linearly and the gamma dose decreased exponentially as the depth was deepened. The factor expressed energy level, $D_{20}/D_{10}$, of the total dose was 0.718. Conclusion : Through the direct measurement using the two ion chambers, which is made different wall materials, and computer calculation of isodose distribution using MCNP simulation method, we have found the dose characteristics of low fluence fast neutron beams. If the power supply and the target material, which generate high voltage and current, will be developed and gamma contamination was reduced by lead or bismuth, we think, it may be possible to accelerator-based BNCT.