• Journal of the Korean Society for Heat Treatment
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• v.3 no.4
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• pp.23-40
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• 1990

This study has been carried out to investigate into some effects of Mn content with varying amounts and austenite grain size on hardenability in boron-added Fe-C-Cr-Mo alloy systems. (1) Austenite grains have been found to hardly grow in the temperature range of $900^{\circ}C$ to $950^{\circ}C$, whereas they grow rapidly in the temperature range of $975^{\circ}C$ to $1100^{\circ}C$. (2) Austenite grain growth is considerably small with increasing holding time at a given austenitizing temperature and is, in particular, hardly found to occur at a temperature of $900^{\circ}C$. (3) The hardenability improves ramarkably as Mn content is increased at three different austenitizing temperatures $900^{\circ}C$, $1000^{\circ}C$ and $1100^{\circ}C$. (4) The maximum hardenability is obtained from steels A, B and C austenitized at the $900^{\circ}C$, although Mn content is varied in each specimen.

• Journal of Biomedical Engineering Research
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• v.6 no.1
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• pp.37-46
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• 1985

Development of a dental Ni-Cr alloy system for porcelain veneering crown and bridge was studied in this research. The principles of alloy design were a) It should not contain toxic beryllium. b) It should have low melting Point. c) It should be easily ground and polished. d) It should possess an adequate strength to resist the deformational force In the mouth. e) It should be bondable Ivith porcelain by chemically. After investigating the effect of minor elements such as boron and rare earth metals on the mechanical properties of the Ni-Cr alloy system, the compromised ideal composition for dental use was determined. The composition was l9.6%, Cr, 5.6% Mo, 3.4% Si, 1, 0% Fe, 0.01% Ti, 0.5-1.0% B, 0.2-0.6% misch metal, balance Ni. To compare the performance of experimental alloy with commercially available alloys, the properties such as strength, melting point, and bond strength were measured. The results Ivere as follows: a) Boron increases the strength of the alloy but reduces the elongation. b) Misch metal increases the strength when the boron content is low, but does not increase the strength when boron content is high. And it reduces the elongation drastically, c) Mechanical strength of the experimental alloy was not superior to commercially available Be containing alloy, but handling performance such as castability, ease of granting and polishing, and cuttability were superior to the Be containing alloy.

• Coupled systems mechanics
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• v.2 no.3
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• pp.271-288
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• 2013

In the present study an elastic-plastic strain analysis is carried out for fibrous composites by using numerical modeling. Application of homogeneous transversely-isotropic model was chosen based on problem solution of a square plate with a circular hole under uniaxial tension. The results obtained in this study correspond to the solution of fiber model trial problem, as well as to analytical solution. Further, numerical algorithm and software has been developed, based on simplified theory of small elastic strains for transversely-isotropic bodies, and FEM. The influence of holes and cracks on stress state of complicated configuration transversely-isotropic bodies has been studied. Strain curves and plasticity zones that are formed in vicinity of the concentrators has been provided. Numerical values of effective mechanical parameters calculated for unidirectional composites at different ratios of fiber volume content and matrix. Content volume proportions of fibers and matrix defined for fibrous composite material that enables to behave as elastic-plastic body or as a brittle material. The influences of the fibrous structure on stress concentration in vicinity of holes on boron/aluminum D16, used as an example.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.1
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• pp.25-32
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• 2020

Generally, high-temperature, high-pressure, high-priced sintering equipment is used for diamond sintering, and conductivity is a problem for improving the surface modification of the sintered body. In this study, to improve the efficiency of diamond sintering, we identified a new process and material that can be sintered at low temperature, and attempted to develop a composite thin film that can be discharged by doping boron gas to improve the surface modification of the sintered body. Sintered bodies were sintered by mixing Si and two diamonds in different particle sizes based on CIP molding and HIP molding. In CVD deposition, CVD was performed using WC-Co cemented carbide using CH₄ and H₂ gas, and the specimen was made conductive using boron gas. According to the experimental results of the sintered body, as the Si content is increased, the Vickers hardness decreases drastically, and the values of tensile strength, Young's modulus and fracture toughness greatly increase. Conductive CVD deposited diamond was boron deposited and discharged. As the amount of boron added increased, the strength of diamond peaks decreased and crystallinity improved. In addition, considering the release processability, tool life and adhesion of the deposition surface according to the amount of boron added, the appropriate amount of boron can be confirmed. Therefore, by solving the method of low temperature sintering and conductivity problem, the possibility of solving the existing sintering and deposition problem is presented.

• Analytical Science and Technology
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• v.17 no.1
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• pp.8-15
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• 2004

The detection efficiencies of the several solid track detectors were investigated for the determination of boron content in aqueous solution by using the alpha muti-Radioisotope(RI) source. Polycarbonate (Lexan and CR-39) and cellulose nitrate (CN-85 and LR-115) were selected as materials for alpha track detection of boron. Alpha muti-RI source, uranium metal particles and boron standard solution were used for alpha emission. In this study, four solid track detectors(CN-85, LR-115, Lexan and CR-39) were characterized under various etching conditions as well as neutron irradiation conditions. As a result, the CN-85 was turned out to be best to provide good efficiency among the four detectors. The selected solid track detector was utilized for the determination of trace amount of boron in aqueous sample and its results were discussed in the text.

• 연구논문집
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• s.29
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• pp.141-149
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• 1999

Brazing of Fe-Cr-Al alloy was carried out at $1200^{\circ}C$ in vacuum furnace using nickel-based filler metals : BNi-5 powder(Ni-Cr-Si-Fe base alloy} and MBF-50 foil (Ni-Cr-Si-B). The effect of boron content on the stability of oxide scale on the brazed joint was investigated by means of cyclic oxidation test performed at $1050^{\circ}C$ and $1200^{\circ}C$. Apparently, the joints brazed with MBF-50 containing boron showed relatively stable oxidation rates compared to boron-free BNi-5 at both temperatures. However, it was considered that the slower weight loss of MBF-50 brazed specimen wasn’t resulted from the low oxidation rate but from the spallation of oxide layer. The oxide layer consisted of thick spinel oxide on the surface and $Al_2 O_3$ internal oxide layer along the interface between mother alloy and braze, the mother alloy was also eroded seriously by the formation of spinel oxides such as $FeCr_2 O_4$ and $NiCr_2 O_4$ on the surface, likely to be induced by the change of oxide forming mechanism due to diffusion of boron from the braze. On the contrary, the joint brazed with BNi-5 showed the good oxidation resistance during the cyclic oxidation test. It seems that the oxidation can be retarded by the formation of stable $Al_2 O_3$ layer at the surface.

• Korean Journal of Soil Science and Fertilizer
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• v.14 no.3
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• pp.137-145
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• 1981

The mutual effects of calcium, potassium and boron on the growth of the leaf lettuce and its following crop of soybean in the granite soil were observed. The results obtained were as follows : 1. The yields of leaf lettuce and soybean were greatly increased by the application of calcium. It was observed that the calcium content in soybean leaf correlated positively with the yields, the number of pods and dry weight of soybean. 2. The application of calcium was effective by itself on the plant growth, the Ca+B application was better effective, and the best effective plot was $Ca+B_1+K_1$. 3. No significant tendency was observed between the Ca/B ratio in plant tissue and its growth. 4. The application of boron increased calcium absorption in plant tissue regardless of the application of calcium. 5. The number of pods and 100 grains weight of soybean were increased by the application of boron, And a positive correlation was observed between the boron content in soybean leaf and the number of pods of soybean. 6. One basal application of calcium, potassium and boron was effective both on leaf lettuce and on its following crop of soybean.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.3
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• pp.193-198
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• 2013

In general, boron recovery of 40-90% could be achieved by Reverse Osmosis (RO) membranes in neutral pH condition. As an emerging technology, Forward Osmosis (FO) membrane has attracted growing interest in wastewater treatment and desalination. The objective of this study is to evaluate the possibility of the boron removal in radioactive liquid waste by FO. In this study, the performance of FO was investigated to remove boron in the simulated liquid waste as the factors such as pH, osmotic pressure, ionic strength of solution, etc. The pH of feed solution is a major operating parameter which strongly influences to the permeation of boron and more than 80% of boron content can be separated when conducted at pH values less than 7. The water flux is not influenced but the boron flux and permeation rate tends to decrease in the low salt concentration of 1,000 mg/L. The boron flux increases linearly, but the permeation ratio of reducing boron is nearly constant even with changes in the draw solution concentration.

• Analytical Science and Technology
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• v.18 no.1
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• pp.27-34
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• 2005

$Li_2B_4O_7$ and $Na_2B_4O_7$ were synthesized with boron isotopic standard material for the measurement of boron isotopes of positive ions (PTIMS) such as $Li_2BO_2{^+}$ (mass 56, 57) and $Na_2BO_2{^+}$ (mass 88, 89) instead of boron mass 10 and 11. The negative ions (NTIMS) such as $^{10}BO_2{^-}$ and $^{11}BO_2{^-}$(mass 42와 43) were also measured with the same boron isotopic standard material. The precision and accuracy were compared between each method, and prescan of isobaric effect was studied. Good result was obtained from NTIMS method which provided the stable and enough peak intensities with good precision and accuracy. The measurement of boron isotopes were performed in ground water sample with about 8 ng-B ($5{\mu}L$ sample solution) obtained from IAEA for international inter-comparison analysis. The standard deviation was found to be 0.03%. Boron content of this ground water was measured using the NTIMS-IDMS. The result was $1.65{\pm}0.003ug-B/mL$ which was better precision compared to the ICP-AES result.

• Analytical Science and Technology
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• v.16 no.5
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• pp.391-398
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• 2003

Basic research for the determination of boron content in biological sample has been carried out using the PGAA facility of the 24MW research reactor(HANARO). For investigation of characteristics for the measurement condition, neutron flux and its homogeneity were measured at irradiating geometry. The size of thermal neutron beam collimated from beam guide is $2{\times}2cm^2$ at the sample position. The neutron flux measured was the range of $1.0{\sim}6.5{\times}10^7n{\cdot}cm^{-2}{\cdot}s^{-1}$, and flux distribution from center within the radius of 4.5 mm and 9.0 mm was $5.77{\pm}0.71{\times}10^7n{\cdot}cm^{-2}{\cdot}s^{-1}$ and $4.68{\pm}1.64{\times}10^7n{\cdot}cm^{-2}{\cdot}s^{-1}$, respectively. Accordingly, sample size is adjusted within 10 mm for a homogeneous irradiation of high quality. Measurement system is designed to reduce the background source by Compton scattering and to improve the analytical sensitivity. To investigate the energy calibration and Compton suppression effect of gamma-ray counting system, the background conditions on both of Compton and single-mode were measured using NaCl standard. On the other hand, degree of spectral interference for sodium 472 keV peak as a matrix effect in the sample is established for an accurate boron analysis, and then boron content in three certified reference materials (NIST SRM 1570a, 1547, 1573a) was measured by using two modes and the results were compared with each other.