• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.12
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• pp.1329-1334
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• 2003

We prepared EM wave absorbers by using recycled Ba ferrite far GHz frequency, and investigated the effects of carbon additions and preparation temperatures on their EM wave absorption properties. We clarified that it is very important to consider carbon amounts in Ba ferrite and preparation temperature for Ba ferrite EM wave absorbers with high quality.

• Journal of Navigation and Port Research
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• v.28 no.6
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• pp.503-507
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• 2004

We prepared EM wave absorbers by using recycled Sr ferrite for GHz frequency, and investigated the effects of carbon additions and preparation temperatures on their EM wave absorption properties. A Sr ferrite EM wave absorber with the ratio of Sr ferrite: silicon rubber: carbon = 80 : 13.6: 6.4 wt% prepared at 7$0^{\circ}C$ showed -24 dB at 9.4 GHz and -23 dB at 5.5 GHz for 2 mm and 3 mm thickness, respectively.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.245-248
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• 2001

Nomura Kohsan Corp. is producing oxides, such as ZnMn$_2$O$_4$, ZnFe$_2$O$_4$, and ZnO, by burning the used dry manganese cells and by sorting out the remnant materials. It is possible to use the recycled materials of the spent dry batteries as the raw materials of deflection yoke cores. Making hish roasting temperature in the recycling system has an effect in reduction of the impurities. As a result, the loss of the cores using the recycled materials is lower. When using the recycled materials, it is required to add Mg (OH)$_2$. ZnO, and Fe$_2$O$_3$in order to rectify the composition of the MnMgZn ferrite for deflection yoke core applications. Furthermore, in order to disappear ZnMn$_2$O$_4$in the formation, it is necessary to control at higher calcining temperatures. The MnMgZn ferrite of using the recycled materials becomes Toss equivalent to the conventional material. TDK Corp. is manufacturing the deflection yoke cores from 1996 using the material recycled from the spent dry batteries.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.17-22
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• 2004

We prepared EM wave absorbers by using recycled Ba and Sr ferrites for GHz frequency, and investigated the effects of carbon additions, thickness and preparation temperatures on their EM wave absorption properties. We clarified that it is very important to consider carbon amounts in Ba and Sr ferrites and preparation temperature for Ba and Sr ferrite EM wave absorbers with high quality. In this study, the developed a EM Wave absorber satisfying over 20 dB.

• Journal of the Korean Ceramic Society
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• v.48 no.5
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• pp.454-457
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• 2011

We report the preparation of nanocrystalline cobalt ferrite, $CoFe_2O_4$, particles using recycled $Co_3O_4$ and their surface coating with silica using micro emulsion method. Firstly, the $Co_3O_4$ powders were separated from waste cemented carbide with acid-base chemical treatment. The cobalt ferrite nanoparticles with the size 10 nm are prepared by thermal decomposition method using recycled $Co_3O_4$. $SiO_2$ was coated onto the $CoFe_2O_4$ particles by the micro-emulsion method. The $SiO_2$-coated $CoFe_2O_4$ particles were studied their physical properties and characterized by X-ray diffraction (XRD), high resolution-transmission electron microscopy (TEM) analysis and CIE Lab value.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.4
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• pp.406-413
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• 2004

In this study, we investigated the reflection coefficient of absorbers fur mobile phone on average Particle size and preparation temperature of specimens. We used recycled MnZn ferrite with initial permeability of 2,500 and 10,000 as starting materials. Absorption ability increased at 1.8 ㎓ which is frequency fur mobile phones with increasing average particle size. We developed a sheet type electromagnetic wave absorber with the thickness of 1 mm which showed reflection coefficient of -3.8 ㏈ at 1.8 ㎓.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.1
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• pp.9-15
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• 2023

The cement is a typical CO₂ emission industry. Manufacturing process improvements and increased use of alternative materials are needed to reduce energy consumption and CO₂ emissions. This study confirmed the basic characteristics of cement hydration by sintering CAF at low temperature as a CO₂ adsorbent material. For the hydration product of the synthetic CAF, crystal phase analysis, porosity, and structural images were confirmed, and the compressive strength was measured. The replacement rate of SCAF was 10, 20, and 100 %, and the compressive strength tended to decrease as the replacement rate increased. In addition, when the SCAF substitution rate is 100 %, the hydration products of the early age are calcium aluminum oxide hydrate (Ca₃Al₂O₆ x H₂O) and calcium iron hydroxide (Ca₃Fe(OH)₁₂), and at substitution rates of 10 and 20 %, CAF compounds other than general cement hydrates brownmillerite was observed. As for the porosity, the pore size increased and the porosity increased with the increase of the replacement ratio. As a result of this study, CAF manufactured by low-temperature sintering seems to be difficult to use alone and general curing for utilization as a CO₂ adsorbing material.

• Nuclear Engineering and Technology
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• v.55 no.9
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• pp.3441-3449
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• 2023

We determined the radiation shielding properties for 10CaO-xPbO-(90-x) deteriorated silica gel (DSG) glass system (x = 20, 25, 30, 35, 40, and 45 mol.%). The mass attenuation coefficient (MAC) has been estimated at photon energies of 74.23, 97.12, 122, 662, 1173, and 1332 keV using a narrow beam X-ray attenuation and transmission experiment, the XCOM program, and a PHITS simulation. The obtained MAC values were applied to estimate the half value layer (HVL), mean free path (MFP), effective atomic number, and effective electron density. Results show that the MAC value of the studied glasses ranges between 0.0549 and 1.4415 cm²/g, increases with the amount of PbO, and decreases with increasing photon energy. The HVL and MFP values decrease with increasing PbO content and increase with increasing photon energy. The recycled glass, with the addition of PbO content (20-45 mol.%), exhibited excellent radiation shielding capabilities compared to standard barite and ferrite concretes and some glass systems. Moreover, the experimental radiation shielding parameters agree with the XCOM and PHITS values. This study suggests that this new waste-recycled glass is an effective and cost-saving candidate for X-ray and gamma-ray shielding applications.

• Resources Recycling
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• v.9 no.1
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• pp.63-69
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• 2000

Ferromanganese dust is an oxide substance of Mn. If imprities are removed and oxidation degree is controlled, the dust can be recycled for soft ferrite materials. The ferromanganese dust contained about 7 kinds of impurities, expecially about 9000 ppm of $SiO_2$ contents of the ferromanganese dust from 9000 ppm to under 500 ppm by fritting method. The $SiO_2$ in ferromanganese dust can be converted into water soluble compounds by alkali fritting and removed by water leaching. KOH and NaOH were used. The most effective conditions to get rid of $SiO_2$ from the dust are that the weight ratio of alkali to ferromanganese dust is 1.75 and fritting is run at $550^{\circ}C$ for 1 hour.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.443-450
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• 2021

The effects of blast furnace slag(BFS) and desulfurized gypsum(FDG) on the compressive strength of CFBA, and self-hydration of CFBA were studied. CFBA has self-hydrating and hardening properties, and it can be seen that the compressive strength of CFBA can be improved by using appropriate amounts of BFS and FDG. In addition, the self-hardening properties of CFBA are similar to the hydration reaction of 4CaO·Al₂O₃·Fe₂O₃ (C₄AF), a cement clinker mineral, and when free-CaO, CaSO₄ and CaCO₃ coexist, Compressive strength of CFBA is expressed by the formation of calcium carbo compounds and hydrates of ettringite, calcium silicate, and calcium aluminate.