• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.226-226
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• 2010

Boron Nitride (BN) doped GeSbTe films were grown by the ion beam sputtering deposition (IBSD). The in-situ sheet resistance data and the x-ray diffraction patterns showed the crystallization is suppressed due to the BN incorporation. The phase change speed in BN doped GeSbTe films were investigated using the static tester equipped with nanosecond pulsed laser. The phase change speed for BN doped GST films become faster than the corresponding values for an undoped GST film. The Johnson-Mehl-Avrami(JMA) plot and Avrami coefficient for laser crystallization showed that the change in growth mode during the laser crystallization is a most important factor for the phase change speed in the BN doped GST films. The JMA results and the atomic force microscopy (AFM) images indicate that the origin of the change in the crystalline growth mode is due to an increase in the number of initial nucleation sites which is produced by the incorporated BN. In addition, the retension properties for the laser writing/erasing are remarkably improved in BN doped GeSbTe films owing to the stability of the incorporated BN.

• Ceramist
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• v.22 no.1
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• pp.36-55
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• 2019

Atomically thin two-dimensional (2D) nanomaterials, including transition metal dichalcogenides (TMDs), graphene, boron nitride, and black phosphorus, have opened up new opportunities for the next generation optoelectronics owing to their unique properties such as high absorbance coefficient, high carrier mobility, tunable band gap, strong light-matter interaction, and flexibility. In this review, photodetectors based on 2D nanomaterials are classified with respect to critical element technology (e.g., active channel, contact, interface, and passivation). We discuss key ideas for improving the performance of the 2D photodetectors. In addition, figure-of-merits (responsivity, detectivity, response speed, and wavelength spectrum range) are compared to evaluate the performance of diverse 2D photodetectors. In order to achieve highly reliable 2D photodetectors, in-depth studies on material synthesis, device structure, and integration process are still essential. We hope that this review article is able to render the inspiration for the breakthrough of the 2D photodetector research field.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3239-3242
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• 2013

An improved rapid method for determination of the fatty acid composition using modified methylation procedure was compared with the AOAC reference procedure based on the methylation of fatty acid with the addition of BF3 catalyst before and while heating. The new method is useful for research and routine quality control and has a number of advantages over the reference procedure which are more rapid, simple and also reliable. Applicability of the modified methylation method was confirmed with three vegetable oil samples (palm oil, coconut oil and olive oil). Based on the validation method results, we obtained that a quite linear calibration curve of fatty acids was performed with $R^2$ in range of 0.9972-0.9994. The sensitivity of gas chromatography instrument was able to analyze the fatty acids up to a few ppm, the precision and accuracy were good enough with the %RSD between 1.5%-19.5% and the recovery of linolenic acid was 99.1% in the range of 80.0%-113.3%.

• Journal of Powder Materials
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• v.23 no.6
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• pp.447-452
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• 2016

Neodymium-iron-boron (Nd-Fe-B) sintered magnets have excellent magnetic properties such as the remanence, coercive force, and the maximum energy product compared to other hard magnetic materials. The coercive force of Nd-Fe-B sintered magnets is improved by the addition of heavy rare earth elements such as dysprosium and terbium instead of neodymium. Then, the magnetocrystalline anisotropy of Nd-Fe-B sintered magnets increases. However, additional elements have increased the production cost of Nd-Fe-B sintered magnets. Hence, a study on the control of the microstructure of Nd-Fe-B magnets is being conducted. As the coercive force of magnets improves, the grain size of the $Nd_2Fe_{14}B$ grain is close to 300 nm because they are nucleation-type magnets. In this study, fine particles of Nd-Fe-B are prepared with various grinding energies in the pulverization process used for preparing sintered magnets, and the microstructure and magnetic properties of the magnets are investigated.

• Proceedings of the Korean Society of Food Science and Nutrition Conference
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• 2001.12a
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• pp.126-133
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• 2001

As dietary intakes levels of Calcium decrease below those recommended by health authorities the incidence of Osteoporosis is set to continue to rise. To address this issue it is becoming necessary to fortify regularly consumed foods such as cereals, biscuits etc. with ingredients such as AquaCal. AquaCal is a natural, organic source of calcium that is produced from calcified seaweed, Phymatolithon and Lithothamnion and can be utilised for Calcium and magnesium supplementation in a broad range of foods and beverages. AquaCal presents a great potential over other calcium sources because of its porous structure and it composition associating key minerals as calcium, magnesium and boron in addition to being neutral in taste in applications. Once consumed the efficacy of AquaCal must then be verified therefore a bioavailability a comparative feeding study to assess effects of AquaCal on bone density was carried out. There was no significant difference in bioavailability based on calcium absorption between AquaCal and Limestone however the weights of the femurs of the animals fed AquaCal did significantly increase over the group fed Limestone. As a natural and organic mineral AquaCal has many different fields of application.

• Journal of the Korean Magnetic Resonance Society
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• v.10 no.2
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• pp.197-202
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• 2006

[ $^{11}B$ ] nuclear magnetic resonance (NMR) measurements were performed on the single crystals of $TbB_4$ to investigate local electronic structure and 4f spin dynamics. $^{11}B$ NMR spectrum, Knight shift, spin-lattice and spin-spin relaxation rates were measured down to 4K at 8T. $^{11}B$ NMR shift and linewidth are huge and strongly temperature dependent due to the 4f moments. In addition, both are proportional to magnetic susceptibility, indicating that the hyperfine field at the boron site originates from the 4f spins of Tb. Below $T_N$, the single broad resonance peak of $^{11}B$ NMR splits into several peaks reflecting the local magnetic fields due to antiferromagnetic spin arrangements. The longitudinal and the transverse relaxation rates, $1/T_1\;and\;1/T_2$, independent of temperature above $T_N$, decreases tremendously confirming huge suppression of spin fluctuation below $T_N$.

• 연구논문집
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• s.24
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• pp.161-174
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• 1994

The Ni-Al intermetallic compound that has the greatest potential to be commercialized shows the high ductility at room temperature with the addition of boron, but has extremely low ductility at high temperature and oxidation environment. On this research work, the changes of microstructure and compressive fracture properties were studied in ($NiAl+Ni_3Al$) two-phase alloys. The precipitation behavior of $Ni_3Al$ after solution treatment at $1300^\circC$ for 14hrs and aging treatment at $800^{\circ}C$ for 14hrs was varied with Al content in ($NiAl+Ni_3Al$) two-phase alloys. These microstructure could be modified dramatically by suitable heat treatments. Martensite or martensite plus $Ni_3Al$ microstructure was obtained upon oil quenching from $1300^\circC$. Aging of Martensite at $800^\circC$ resulted in the $Ni_3Al$ plus NiAl phase. The compressive fracture strength and compressive fracture strain were improved by the $Ni_3Al$ plus NiAl phase mixtures at room temperature and $1100^\circC$. Microcracks are observed mostly in the region of NiAl and the interface of $NiAl-Ni_3Al$ phase after compressive test at room temperature. In the case of high temperature compressive test, microcracks are formed in the region of $Ni_3Al$ phase.

• Nuclear Engineering and Technology
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• v.53 no.10
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• pp.3133-3150
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• 2021

This work deals with the validation of a high-fidelity multiphysics system coupling the Serpent 2 Monte Carlo neutron transport code with SUBCHANFLOW, a subchannel thermalhydraulics code, and TRANSURANUS, a fuel-performance analysis code. The results for a full-core pin-by-pin burnup calculation for the ninth operating cycle of the Temelín II VVER-1000 plant, which starts from a fresh core, are presented and assessed using experimental data. A good agreement is found comparing the critical boron concentration and a set of pin-level neutron flux profiles against measurements. In addition, the calculated axial and radial power distributions match closely the values reported by the core monitoring system. To demonstrate the modeling capabilities of the three-code coupling, pin-level neutronic, thermalhydraulic and thermomechanic results are shown as well. These studies are encompassed in the final phase of the EU Horizon 2020 McSAFE project, during which the Serpent-SUBCHANFLOW-TRANSURANUS system was developed.

• Journal of Information Processing Systems
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• v.18 no.5
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• pp.688-700
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• 2022

A composite bionic soft gripper integrated with electromagnets and magneto-active elastomers is designed by combining the structure of the human hand and the snake's behavior of enhancing friction by actively adjusting the scales. A silicon-based polymer containing magnetized hard magnetic particles is proposed as a soft finger, and it can be reversibly bent by adjusting the magnetic field. Experiments show that the length, width, and height of rectangular soft fingers and the volume ratio of neodymium-iron-boron have different effects on bending angle. The flexible fingers with 20 vol% are the most efficient, which can bend to 90° when the magnetic field is 22 mT. The flexible gripper with four fingers can pick up 10.51 g of objects at the magnetic field of 105 mT. In addition, this composite bionic soft gripper has excellent magnetron performance, and it can change surface like snakes and operate like human hands. This research may help develop soft devices for magnetic field control and try to provide new solutions for soft grasping.

• Journal of the Korean Physical Society
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• v.81
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• pp.942-947
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• 2022

We report the electrical transport properties of a dual-gate graphene device placed on a CaF₂ substrate. A hexagonal boron nitride top-gate dielectric was introduced to confirm the electrical characteristics of the CaF₂/graphene transistor because it is difficult to inject sufficient carriers through the CaF₂ substrate owing to its thickness of 500 ㎛, and the typical ambipolar behavior of graphene with a slight n-doping effect was clearly observed. In addition, we used a polymethyl methacrylate (PMMA) film as a top-gate dielectric for large-scale graphene devices grown via chemical vapor deposition, which was transferred onto a CaF₂ substrate. We controlled the high gate leakage current caused by the breakdown of the polymer due to non-uniformity by applying the film-transfer process rather than the direct coating method on the graphene device. Furthermore, the transport properties of large-area graphene in contact with CaF₂ are discussed with respect to the effect of top-contacted PMMA.