• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.2
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• pp.133-156
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• 2013

Natural analogue studies play an important role in the safety case which requires multiple lines of evidence including the safety assessment for the geological disposal of radioactive wastes. In this study, foreign status of natural analogue studies was investigated by summarizing natural analogue results according to the research topics related with repository materials and radionuclide migration and retardation. Main results, issues, and applicability of the foreign natural analogue studies were also analyzed. The results of domestic natural analogue studies were classified into studies using uranium ore bodies, rocks, groundwaters, and archeological artifacts, respectively, and their main results were summarized. There are massive materials for natural analogue studies which have been carried out during last several decades but they have not been actively applied to the safety assessment and safety case development for the radioactive waster disposal. Thus, in this study, applicable methods of natural analogues were summarized and a methodology for improving their applicability was examined. Natural analogue study is apparently necessary to improve and illustrate the reliability of safety assessment for a radioactive waste repository. Therefore, it is necessary to develop a methodology and construct a natural analogue information database for the application of the results from natural analogue studies to safety case development.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 2005.04a
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• pp.63-64
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• 2005

• Journal of Aerospace System Engineering
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• v.10 no.3
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• pp.59-62
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• 2016

In this study, an investigation was performed on the mechanical properties of the natural-fiber-composite structure. The specimen was manufactured using the Vacuum Assisted Resin Transfer Molding (VARTM) method. The flax-fiber materials were adopted for the natural fiber composite, and vinyl-ester resin was also adopted. After a manufactured specimen was obtained, a mechanical test was carried out. The mechanical properties of the experiment results were compared with those of the natural-composite data cited from a number of other references.

• Journal of Korean Society on Water Environment
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• v.32 no.6
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• pp.546-551
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• 2016

In this study, capping with recycled aggregate and natural zeolite in marine sediment was performed to investigate its inhibitory effect on pollutants released from sediment to seawater. An experiment was performed by capping with amendments for 60 days, and concentrations of organic matter (COD), nitrate, phosphate and metallic elements (Ni, Zn, Cu, Pb, Cd, As, and Cr) were measured. Two capping materials effectively suppressed pollutant release. Recycled aggregate showed better effectiveness for organic pollutant, nitrate and phosphate release. Meanwhile, natural zeolite was effective for metallic elements. As a result, recycled aggregate and natural zeolite can be considered as cost-effective/inexpensive capping material candidates. Also, the capping material can be selected according to the target pollutant.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1998.11a
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• pp.183-183
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• 1998

Telomerase synthesizes telomeric DNA repeats onto chromosome ends de novo. Telomerase activation and telomere shortening in human somatic cells have been implicated in cell tumorigenesis and immortalization. In order to find the potential inhibitors against telomerase activitiy which can be used as potential anticancer agents, we screened about 100 kinds of natural products after partition into n-hexane, ethyl acetate and aqueous layers from methanol extracts. The inhibitory effects of these materials against telomerase enzyme activity were tested in 293T cell culture using telomeric repeat amplification protocol(TRAP). The incorporation of $\^$32/P-dGTP into amplified DNA was measured by adsorption to Whatman DE81 paper instead of using TRAP assay for screening the extracts of natural products. Strong effective compounds were not found in this study but DE81 filter spotting method may be a useful model for the screening. Some of the compounds which showed somewhat inhibitory effects had cytotoxic effects also.

• The Korean Journal of Food And Nutrition
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• v.32 no.1
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• pp.41-49
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• 2019

Carotene, xanthophyll, carotenoid anthocyan, phycopyrine, chlorophyll, and monascus pigments are used as natural coloring agents since they are more stable to human body than synthetic coloring agents. Among them, monascus pigments are a natural red pigment produced by the Monascus purpureus. For the development of edible paint using natural pigment, Monascus purpureus strain was cultured at a temperature of $35^{\circ}C$ for 15 days on a PDYA plate and liquid medium to produce a red pigment. In addition, a large amount of the red pigment was extracted from Hongkuk Koji in parallel with water extraction and ultrasonic wave extraction. At this time, the yield of ultrasonic extract was 2~4 times higher. Thus, Monascus purpureus strains, etc. were prepared by freeze-drying powder. In conclusion, natural paints made with red pigments have enabled the development of been edible paints that can be used as eco-friendly materials with good viscosity, enhanced spread ability and coloration.

• Journal of Information Display
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• v.2 no.3
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• pp.32-38
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• 2001

The most important parameter for TV application of LCD is a fast switching time for the display of moving image. To achieve faster switching time, the novel LC single materials with large dielectric anisotropies ($16{\sim}20$), high clearing temperatures ($195.5{\sim}237.4^{\circ}C$), broad nematic ranges (up to 169.9 $^{\circ}C$) and high birefringence ($0.254{\sim}0.2200$) were developed. KUR-series LC mixtures blended these single materials having significantly higher clearing temperatures and dielectric anisotropy values compared with conventional LC mixture. Especially, their clearing temperatures are $10{\sim}30^{\circ}C$ higher than their host mixture. These LC mixtures showing about lOms of high-speed switching time in Tv/Monitor of TFT LCD, is short enough to be addressed in a single time frame of 60Hz (16.7 ms). The threshold voltage $V_{th}$ was low enough to operate at a driving voltage of 5 V. The VHR values were found to be high enough for TFT-LCD in wide temperature range. Our novel LC mixtures are suitable materials for the inclusion in to LC mixtures for TV application of TN-LCD

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.4
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• pp.106-112
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• 2013

Compression ratio is an important factor affecting engine performance and emission characteristics since thermal efficiency of spark ignition engine can be theoretically improved by increasing compression ratio. In order to evaluate the effect of compression ratio change in HCNG engine, natural gas engine was employed using HCNG30 (CNG 70 vol%, hydrogen 30 vol%). Combustion and emission characteristics of CNG and HCNG fuel was analyzed with respect to the change of compression ratio at each operating condition. The results showed that thermal efficiency improved and $CH_4$, $CO_2$ emission decreased with the increase in compression ratio while $NO_x$ emissions were decreased at a certain excess air ratio condition. Higher thermal efficiency and further reduction of exhaust emissions can be achieved by the increase of compression ratio and the retard of spark timing.

• Korean Journal of Materials Research
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• v.9 no.4
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• pp.409-413
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• 1999

Recently, the polymeric insulators have been accepted in several countries for the outdoor high voltage applications. In comparison with the conventional porcelain, polymeric insulators offer various advantages such as light weight, superior vandal resistance and better contamination performance. The outdoor polymeric insulating materials such as silicone rubber, ethylene propylene diene monomer(EPDM), ethylene vinyl acetate(EVA) and epoxy are aged such as silicone rubber, ethylene propylene diene monomer(EPDM), ethylene vinyl acetate(EVA) and epoxy are aged under the various natural environment with the long-term performance in outdoor. In this paper, the effects of UV-under the various natural environment with the long-term performance in outdoor. In this paper, the effects of UV-ray on the surface of silicone rubber were investigated by using the weather-Ometer. The accelerated aging stresses were simulated by UV radiation, high temperature and humidity as well as water spray. These aging characteristics were examined through contact angle measurements, tracking resistance test, FT-IR and SEM/EDS analysis. The experimental results showed that tracking resistance decreases with increase in the UV-ray irradiation period. But the surface of silicone rubber kept hydrophobicity. It is found that the inorganic filler such as)$ Al(OH_3$ improves tracking resistance and the $Tio_2$is very effective in preventing degradation of silicone rubber surface from UV-ray.

• Advanced Composite Materials
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• v.16 no.4
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• pp.315-334
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• 2007

In the present study, chopped henequen natural fibers without and with surface modification by electron beam (E-beam) treatment were incorporated into a polypropylene matrix. Prior to composite fabrication, a bundle of raw henequen fibers were treated at various E-beam intensities from 10 kGy to 500 kGy. The effect of E-beam intensity on the interfacial, mechanical and thermal properties of randomly oriented henequen/polypropylene composites with the fiber contents of 40 vol% was investigated focusing on the interfacial shear strength, flexural and tensile properties, dynamic mechanical properties, thermal stability, and fracture behavior. Each characteristic of the material strongly depended on the E-beam intensity irradiated, showing an increasing or decreasing effect. The present study demonstrates that henequen fiber surfaces can be modified successfully with an appropriate dosage of electron beam and use of a low E-beam intensity of 10 kGy results in the improvement of the interfacial properties, flexural properties, tensile properties, dynamic mechanical properties and thermal stability of henequen/polypropylene composites.