• Nuclear Engineering and Technology
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• v.51 no.8
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• pp.1964-1969
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• 2019

The safety and efficiency of nuclear reactors largely depend on the monitoring and control of nuclear radiation. Due to the unique nuclear-physical characteristics, Hf is one of the most promising materials for the manufacturing of the control rods and the emitters of neutron detectors. It is proposed to use the Compton neutron detector with the emitter made of Hf in the In-core Instrumentation System (ICIS) for monitoring the neutron field. The main advantages of such a detector in comparison the conventional β-emission sensors are the possibility of reaching of a higher cumulative radiation dose and the absence of signal delays. The response time of the detection is extremely important when a nuclear reactor is operating near its critical operational parameters. Taking Hf as an example, the general principles for calculating the chains of materials transformation under neutron irradiation are reported. The influence of ^179m1Hf on the Hf composition changing dynamics and the process of transmutants' (Ta, W) generation were determined. The effect of these processes on the absorbing properties of Hf, which inevitably predetermine the lifetime of the detector and its ability to generate a signal, is estimated.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.335-342
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• 2022

In this study, self-healing hybrid capsules were prepared by mixing self-healing solid capsules and self-healing microcapsules using inorganic materials as core materials. Self-healing hybrid capsules were mixed with 3 % according to the composition ratio of 3:7, 5:5, and 7:3 based on the mass of the cement to prepare a self-healing cement composite material. The healing properties of crack self-healing hybrid capsules were evaluated through hydrostatic water permeability test and surface crack monitoring. It was found that the self-healing hybrid capsules prepared by mixing the composition ratio of the self-healing solid capsules and the self-healing microcapsules at 7:3 has a great effect on improving the crack self-healing performance.

• Korean Journal of Mineralogy and Petrology
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• v.34 no.4
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• pp.241-253
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• 2021

Manganese nodules have been found in the shallow water depth of the Arctic Ocean as well as in the abyssal plains of the Pacific and Indian Oceans, but detailed study for them were rarely investigated. Manganese nodules, collected from the East Siberian Sea through the Arctic Expedition using Araon ice braking vessel, have a high potential for Mn mineral resources because they have high Mn content with high Mn/Fe ratio. This study investigated the external form, size and weight, internal texture for the non-spherical manganese nodule, which has about 7 % of total nodule from the East Siberian Sea. This study also researched the relative Mn-oxide mineral composition using the peak area ratio of X-ray diffraction pattern and their chemical composition. All data obtained from non-spherical nodules were compared with the spherical ones. Ellipsoidal, platy and irregular types are common among 5 groups of non-spherical manganese nodule based on the external form, and major axis and weight have positive relationship. All non-spherical manganese nodules have core mainly composed of mud sediments. The average Mn oxide mineral contents in nodules are birnessite, buserite and todorokite in descending order. Although mineral composition does not show any correlation with the external form, kind of core or internal structure, todorokite and buserite contents tend to increase and birnessite content decrease from the surface to the core in the nodule. Non-spherical manganese nodules have higher Mn content and Mn/Fe ratio than those from the shallow water depth of the Arctic Sea and even in the deep-sea of the Pacific and Indian Ocean. Although non-spherical nodule is larger and heavier, and has lower Mn content and Mn/Fe ratio than spherical nodule, there are not any differences in mineral composition and internal structure between them. Almost all manganese nodules collected from the East Siberian Sea are attributed to diagenetic process, because they are higher than 5 in Mn/Fe ratio.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.1
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• pp.221-243
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• 1997

The objective of this study was to characterize the mechanical properties of $Y_{2}O_{3}$-containing glass infiltrated ceramic core material, which was made by pressureless powder packing method. A pure alumina powder with a grain size of about $4{\mu}m$ was packed without pressure is silicon mold to form a bar shaped sample, and applied PVA solution as a binder. Samples were sinterd at $1350^{\circ}C$ for 1 hour. After cooling, $Y_{2}O_{3}$-containing glass($SiO_{2},\;Y_{2}O_{3},\;B_{2}O_{3},\;Al_{2}O_{3}$, ect) was infiltrated to the sinterd samples at $1300^{\circ}C$ for 2 hours and cooled. Six different proportions $Y_{2}O_{3}$ of were used to know the effect of the mismatch of the thermal expansion coefficient between alumina powder and glass. The samples were ground to $3{\times}3{\times}30$ mm size and polished with $1{\mu}m$ diamond paste. Flexural strength, fracture toughness, hardness and other physical properties were obtained, and the fractured surface was examined with SEM and EPMA. Ten samples of each group were tested and compared with In-Ceram(tm) core materials of same size made in dental laboratory. The results were as follows : 1. The flexural strengths of group 1 and 3 were significantly not different with that of In-Ceram, but other experimental groups were lower than In-Ceram. 2. The shrinkage rate of samples was 0.42% after first firing, and 0.45% after glass infiltration. Total shrinkage rate was 0.87%. 3. After first firing, porosity rate of experimental groups was 50%, compared with 22.25% of In-Ceram. After glass infiltration, porosity rate of experimental groups was 2%, and 1% in In-Ceram. 4. There was no statistical difference in hardness between two materials tested, but in fracture toughness, group 2 and 3 were higher than In-Ceram. 5. The thermal expansion coefficients of experimental groups were varied to $4.51-5.35{\times}10^{-6}/^{\circ}C$ according to glass composition, also the flexural strengths of samples were varied. 6. In a view of SEM, many microparticles about $0.5{\mu}m$ diameter and $4{\mu}m$ diameter were observed in In-Ceram. But in experimental group, the size of most particles was about $4{\mu}m$, and a little microparticles was observed. The results obtained in this study showed that the mismatch of the thermal expansion coefficients between alumina powder and infiltrated glass affect the flexural strength of alumin/glass composite. The $Y_{2}O_{3}$-containing glass infiltrated ceramic core made by powder packing method will takes less time and cost with sufficient flexural strength similar to all ceramic crown made with slip casting technique.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.5
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• pp.288-302
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• 2017

Accurate measurement of benthic nutrient fluxes (BNF) is a prerequisite for evaluating the effect of sediments on nutrient cycle in the surface water. The intact sediment cores were collected in July 2015 at the midstream of Nakdong River. We identified pre-incubation time (6, 12, 24 hr), dissolved oxygen concentration (90, 70, 50% saturation), diffusive boundary layer thickness (0, 0.6-0.8, 1.2-1.4 mm), and incubation temperature (10, 17, 20, $25^{\circ}C$) as the most important control factors, and measured the BNF fluctuation with the variation of these factors using the laboratory sediment core incubation method. Since the chemical composition, redox condition, hydrodynamic regimes and microbial activities at the sediment-water interface were changed as a result of the alteration of control factors, sediment core incubation should be conducted under as close to the natural conditions of study site as possible, in order to produce the results similar to actual values. Relative percentage differences between two replicates were below 20% in most control factors, which showed satisfactory precision for strict compliance with the experimental conditions and procedures. In the further studies, we will compare the results of core incubation with those of in situ measurements to confirm the accuracy of the sediment core incubation method.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.6
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• pp.34-42
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• 2000

Recently, there is a growing need to develope small-size RF chip inductors operating to GHz to realize high-performance, micro-fabricated wireless communication products. For the development of high-performance RF chip inductors, however, the ferrite-based chip inductors can not be used above 300MHz due to the limitation of the permeability of this material. In this work, small-size, high-performance RF chip inductors utilizing amorphous $Al_2O_3$ core material were investigated. Copper (Cu) with 40${\mu}m$ diameter was used as the coils and the chip inductor size fabricated in this work is $2.1mm{\times}1.5mm{\times}1.0mm$. The external current source was applied after bonding Cu coil leads to gold pads electro-plated on the bottom edges of a core material. The composition of core materials was measured using a EDX. High frequency characteristics of the inductance (L), quality factor (Q), and impedance (Z) of developed inductors were measured using an RF Impedance/Material Analyzer (HP4291B with HP16193A test fixture). The developed inductors have the self-resonant frequency (SRF) of 1 to 3.5 GHz and exhibit L of 22 to 150 nH. The L of the inductors decreases with increasing the SRF. The Z of the inductors has the maximum value at the SRF and the inductors have the quality factor of 70 to 97 in the frequency range of 500 MHz to 1.5 GHz.

• Cartoon and Animation Studies
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• s.46
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• pp.1-22
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• 2017

The practical learning requires the new paradigm in its content of education and environment along with the rapid development of information communication technology and the expansion of digital content industry. Especially, the animation education, core area of digital content industry, has attempted to improve the content and method of education by focusing on creativity, convergence and practical education. However, education environment in the previous form of computer laboratory has not been reflected the characteristics of animation education. In the light of this, this research would suggests the effective education environment implemented animation job competency and the characteristics of animation production. Firstly, the problem of previous educational environment will be explored through looking at computer rooms of domestic Universities. The characteristics of animation production consisted of Pre-production, Main-production, Post-production and elements of animation job competency will be reviewed by focusing on three phases of production, Pre-production, Main-production and Post-production, and six particular jobs, concept art, modeling & texturing, animating, lighting, VFX and compositing. Secondly, 6 types of space adapted from space syntax, possibly explored the embedded meaning of the structure of space and environment, will be reviewed by focusing on integration, separation and interaction. Thirdly, based on the characteristics of animation production, the element of animation job competency, 6 types of space, analytical tools about animation project education will be deducted, and the case study regarding animation studio, Walt Disney studio, will be processed by focusing on its production environment and spatial composition by focusing on Pre-production, Main-production, Post-production. Fifthly, the effective spatial composition for animation project education will be explored based on the interpretation of literature reviews and case study. In regard to this, the research addresses the spatial composition reflected the characteristics of practical learning and job competency in animation education, which differs from the previous form of standardized education spaces.

• The Journal of the Petrological Society of Korea
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• v.21 no.3
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• pp.309-333
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• 2012

Basalt having lots of feldspar phenocryst occurred at the northern and southern slope of the Mt. Halla, Jejudo. Among them, the Sioreum trachybasalt in southern slope consists of abundant phenocrysts of plagioclase in aphanitic groundmass. And the number of plagioclase grains are about 20 per $10cm^2$, and based on 667 grains the sizes are 13~0.7 mm (average 4.23 mm) in length and 8.6~0.5 mm (average 2.3 mm) in width. In according to modal analyses, Sioreum basaltic rock consists mainly of plagioclase (16~28%), olivine, clinopyroxene (1.5~6%) and opaque minerals (~0.1%) of magnetite and ilmenite as phenocryst and microphenocryst and groundmass (60~82%). The compositions of plagioclase, olivine and clinopyroxene are bytownite~andesine, chrysolite~hyalosiderite, augite respectively. Plagioclase phenocrysts show different type of zoning, namely, normal, reversal, patchy, oscillatory type. The An contents of zoned plagioclase mainly increase from core to rim. Those of oscillatory type from core to rim show variations of increase following decrease or decrease following increase, being more enriched in rim or almost same to core. Under the microscope, some plagioclase phenocrysts are especially melted in core part or marginal part, or found as only the remnant remain which resulted from reaction with melt. Some clinopyroxene are also corroded in margin part or found as irregular shape resulted from melting. The characteristics of petrography and compositional variation from core to rim of plagioclase and clinopyroxene, indicate that they are disequilibrium with melt and has been undergone geological environmental changes in magma batch during crystallization including magma mixing with replenishment of more mafic and high temperature melt.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.spc1
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• pp.29-32
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• 2005

This experiment aimed to estimate the effect of imperfect rice on rice palatability. Rice cultivar, Ilpumbyeo, was cultivated by direct-seeding on flooded paddy surface with 11 kg/10a nitrogen application. Palatability of harvested rice was measured by NIR spectroscope. Brown rice was divided according to their appearance namely, perfect, discolored, green-kerneled, and immature opaque with a composition ratio of $75.7\%,\;11.0\%,\;8.0\%,\;and\;5.3\%$ respectively. When the perfect brown rice was milled, the grain were composed of head, cracked, and white core & belly, at $64.7\%,\;25.3\%\;and\;10.0\%$ respectively. The milled rice of discolored brown rice had similar composition with the perfect rice. The milled green-kerneled vice, on the other hand, had $36\%$ head rice and $64\%$ white core & belly rice. The immature opaque brown rice, when milled, had $25.3\%$ white core & belly and $74.7\%$ damage & opaque rice. With the respect to grain quality, the viscosity of white core at belly rice and damaged & opaque rice was lower than that of head rice. In contrast, their protein content was a little higher than that of head rice. The palatability value of pure imperfect rice was much lower than head rice. The palatability value of damaged & opaque rice was the lowest among the imperfect rices. When mixed with head rice, the damaged & opaque rice impacted on the deterioration of vice palatability. Mixing $1\%$ each of white core at belly rice and damaged h opaque rice decreased the palatability value by $5\%$ as compared with the head rice.

• Ocean and Polar Research
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• v.36 no.1
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• pp.13-24
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• 2014

We established the first complete ice core processing method and analytical procedures for fundamental proxies, using a 40.2 m long ice core drilled on the Mt. Tsambagarav glacier in the Mongolian Altai mountains in July 2008. The whole core was first divided into two sub ice core sections and the measurements of the visual stratigraphy and electrical conductivity were performed on the surface of these sub core sections. A continuous sequence of samples was then prepared for chemical analyses (stable isotope ratios of oxygen ($^{18}O/^{16}O$) and hydrogen ($^2H/^1H$), soluble ions and trace elements). A total of 29 insoluble dust layers were identified from the measurement of visual stratigraphy. The electrical conductivity measurement (ECM) shows 11 peaks with the current more than 0.8 ${\mu}A$ Comparing the profiles of $SO_4{^{2-}}$ and $Cl^-$ concentrations to correlate with known volcanic eruptions, the first two ECM peaks appear to be linked to the eruptions (January and June 2007) of Kliuchevskoi volcano on the Kamchatka Peninsula of Russia, which supports the reliability of our ECM data. Finally, the composition of stable isotopes (${\delta}^{18}O$ and ${\delta}D$) shows a well-defined seasonal variation, suggesting that various chemical proxies may have been well preserved in the successive ice layers of Tsambagarav ice core. Our ice core processing method and analytical procedures for fundamental proxies are expected to be used for paleoclimate and paleoenvironmental studies from polar and alpine ice cores.