• Nuclear Engineering and Technology
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• v.56 no.9
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• pp.3545-3552
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• 2024

Polymers have become widely used substrate materials for shielding neutron rays because of their high hydrogen content and easy processing procedures. Rare-earth materials are also being gradually adopted as neutron absorbers because of their considerable thermal neutron absorption cross-sections. This paper utilizes the FLUKA Monte Carlo simulation program to compare the shielding effects of various polymers and rare-earth oxides on neutron rays across different energy ranges. The study investigates the superior shielding materials for neutron radiation in each energy range. Subsequently, a series of materials are simulated by combining the preferred shielding materials for neutron rays in each energy range, exploring the influence of material composition and composite structure on the effectiveness of neutron ray shielding. It is revealed that the preferred material for shielding neutron rays changes for different energy ranges. For low-energy neutron rays, rare-earth oxides such as Sm₂O₃ and Gd₂O₃ demonstrate the most effective shielding, whereas for high-energy neutron rays, polyethylene (PE) provides the best shielding performance. Materials with different compositions show varying preferred structures when dealing with a ²⁵²Cf neutron source. However, in mitigating the secondary gamma rays generated during the neutron shielding process, stacked-type materials exhibit the most effective shielding performance.

• KIEAE Journal
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• v.12 no.5
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• pp.71-76
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• 2012

As reviewed of developments of Korean earth architecture, earth-made buildings have been dwindled gradually since "the new community movement" and earth have been recognized as materials which are not so good to human health and in result, earth-related techniques have been also forgotten. However, recently the earth architecture has been more attracting back many attentions thanks to the people who are interested in health and wellbeing and the earth related techniques or skills got keenly required. The present study has investigated and reproduced earth finishing materials which are based on natural materials as basic stuffs to use them as the finishing materials of the modern earth architecture. For the test, the finishing materials have been divided roughly into sorts of pastes and oils. In case of applying finishing materials onto earth surfaces, the moisture permeability test was conducted to measure a water-absorbing speed, and at the case of using finishing materials for interior works moisture adsorption/desorption test was performed to verify the indoor humidity regulation ability, and further a test to check whether to be stained when contacted with the finishing materials, was conducted. If there is not any stain it might be recognized to be high quality of moisture adsorption/desorption and so seaweed pastes or starches might be used for paste finishing materials and for natural oils, beans are desirable in practical ways. As low-quantity of moisture adsorption materials, linseed oil is most desirable and also beaned water over75% are thought to be useful.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.149-156
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• 2002

Field measurements were carried out in this study to investigate the behavior of cut and cover tunnel such as the distribution and the magnitude of the earth pressure during back fill process of the ground material. Three kinds of measuring instruments, such as the earth pressure load cell, the concrete strain gauge and the reinforcing bar meter of embedded type in concrete structure were installed and measured. Earth pressure load cells, installed after construction of the tunnel lining, measure the outside forces acting on the tunnel lining with radial directions. Three load cells were installed at the crown, the right and the left shoulder of the tunnel, respectively. Three sets of reinforcing bar meter were installed in the double reinforcements of the tunnel lining and their locations were the same with the position of the earth pressure load cells. Concrete strain gauge was installed only one site of the upper compressive part at the tunnel crown. Based on the measuring results in the field, the deformation and the earth pressure acting on the tunnel lining were investigated with the back fill process of the ground material. Considerations on the validity of the measuring results were paid. For the analysis of measurements, after dividing back fill process into three steps, various factors which affect on the behavior of tunnel lining were investigated at each step.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.581-584
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• 2002

A new method for the preparation of lanthanide ions activated strontium aluminates phosphor by combustion method has been proposed. Combustion method consist of the redox reactions between the respective metal nitrates and urea in a preheated funace at $500^{\circ}C$. The luminescence behavior of the phosphor was studied and compared with corresponding phosphor prepared by conventional method. Effect of $Mg^{2+}$ ion concentration in strontium aluminate phosphor was investigated and the maximum luminescence of about $100cd/m^2$ was obtained. This method gave better brightness and small size to the phosphor than made by conventional method.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.10
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• pp.887-894
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• 2000

In this paper, we have studied the effect of earth (Gd, Er) on the various properties (microstructure, shrinkage, initial permeability, permeability as a function of frequency, etc) of Ba-ferrite. The permeabilities were analyzed by Impedance Analyzer(100KHz~40MHz) and Network Analyzer(30KHz~3㎓). As the result of XRD, all of the Ba-ferrite doped with rat earth was found to be Y-hexagonal phase. The resonance frequencies at the maximum imaginary value of complex permeability were observed near 2㎓. The complex permeabilities of the Ba-ferrite doped with Gd$_2$O$_3$at 3wt% and doped with Er$_2$O$_3$at 3wt% and 5wt% as a function of frequency showed the highest value at sintered temperature at 95$0^{\circ}C$/3h.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.878-881
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• 2001

In this paper, we analyzed the characteristics of insulating material with ELB(earth leakage circuit breaker) through tracking experiment and the study was carried out three different types of samples. The tracking is breakdown phenomenon of material surface that is generated on the organic insulating material. The test method applied IEC publication 587. The result of the sample breakdown by tracking was carbonized and resistance of between the electrodes is approximately 300$\Omega$. In the result of DSC analysis, the caloric peak was detected before 100$^{\circ}C$ in product of tracking. It appeared weight loss of 10.87% at 537$^{\circ}C$ on TGA. IR spectrum analysis showed carbon-hydrogen(C-H)bond on molecular structure that is the sample of tracking.

• Journal of the Korean Ceramic Society
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• v.46 no.2
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• pp.181-188
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• 2009

The electrical property and microstructure in $BaTiO_3$ ceramics doped rare-earth ions with intermediate ionic size ($Dy^{3+},Ho^{3+},Y^{3+}$) were investigated. Microstructures have been characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Incorporation of rare-earth ions to $BaTiO_3$ ceramics depended on their ionic radius sensitively. Compared to Ho and Y ions, Dy ions provide $BaTiO_3$ ceramics with the high rate of densification and well-developed shell formation, due to their high solubility in the $BaTiO_3$ lattice, but the microstructure of Dy doped $BaTiO_3$ ceramics is unstable at high temperature, because Dy ions could not play a role of grain growth inhibition, leading to diffuse into $BaTiO_3$ lattice continuously after completion of densification during sintering. Comparing electrical property and microstructure, it is shown that the reliability of capacitor improved by high shell ratio.

• 한국석유지질학회:학술대회논문집
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• autumn
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• pp.71-71
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• 2000

• Proceedings of the Korean Geotechical Society Conference
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• 2001.10a
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• pp.301-313
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• 2001

Reinforced earth is a composite construction material in which the strength of engineering fill is enhanced by the addition of strong tensile reinforcement in variable types. The basic mechanism of reinforced earth involves the generation of frictional forces and bearing resistances between the soil and the reinforcement. The primitive structure of reinforced earth in Korean peninsula were found as the earth wall built around the old fort In about 3rd century Modern reinforced earth was introduced to Korea early 1980, and spreaded tremendously through the nation. Among them, not a few reinforced earth walls which were built ignored over all stabilities have been collapsed. In this paper basic concepts, economic benefits, design considerations and future applicable trends of reinforced earth are reviewed in simple manners.

• Journal of the Korean Society of Earth Science Education
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• v.1 no.1
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• pp.111-118
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• 2008

This study is aimed at analyzing earth conception the nine pre service teachers who are majoring in earth science education and classifying a special feature from the ontological categories. Open ended questionnaires and semi structured interviews which meant to contribute to identifying ontological categories of concepts involving study area were designed. Pre service teachers' ontological category about earth conception most showed to dynamic and proto process. In the results show that many pre service teachers recognize simply the conception to a material, a condition and a conversion of the state changing. Most of the pre service teachers show their intermediate understanding level about the earth inner construction according to the analyzed results of the drawing tasks and interviews. The main alternative conceptions show them through a definition of the plate, a wording definition between lithosphere and asthenosphere, a feature of the plate boundary, a heat convection in the earth inner, the earth inner heat source, the earth inner structure, a physical feature of the mantle.