• Transactions of the KSME C: Technology and Education
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• v.3 no.4
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• pp.257-264
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• 2015

To maintain sustainability of nuclear energy as an important energy source, both safety problem and Spent Nuclear Fuels(SNFs) problem should be solved. In case of Gen-IV reactors such as fast reactor, SNFs can be used as fuels by using fast neutrons. It can be a suitable treatment method of high-level waste in near future. Liquid metals such as Sodium or Lead-Bismuth Eutectic (LBE) can be possibly used as a coolant to use fast neutrons. In this paper, it was described that natural circulation parameter studies, design analyses, material selections and a completion of facilities. To develop a natural circulation facility, thermal hydraulic analyses were performed. Installation technique of liquid metal natural circulation were secured.

• Journal of the Korean Society of Marine Environment & Safety
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• v.7 no.1
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• pp.7-14
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• 2001

The amount of petroleum consumption has been Increased according to the industrialization and It leads to the increase of the possibility of marine oil pollution. In Korea, some countermeasures including oil skimmer, gelling agent and herding agent of oil have been used for the remediation of the pollution. However, most of them have lets of shortcomings in the application under in-situ condition, because they are sensitive to the situation such as geographical feature, the wind and the tide. In reported literature, the natural powdered oil absorbent which is made of peat moss is an effective mean to clean spilled oil from lake or coast. However, the peat moss is a natural resource which is only Produced from a specific cold weather are like Canada. This indicates that the alternative materials which is readily obtained from everywhere are needed for powdered oil absorbent. Therefore. in the study, same natural materials including pine leaves and straw are tested as the alternative materials for the absorbent. The raw materials were dried and treated by heat at various temperature during several Periods and then. shattered by a grain cracking machine. The oil sorption capacity of the prepared materials was compared according to the methods of heat treatment and their sizes. The proportion of hydrogen cyanide to combustion of the absorbents was measured to confirm their final disposal methods. The biodegradability test of the absorbents was carried our to evaluate possibility of a side pollution in the coast. In was found that the heat treatment of pine leaves enhanced the capacity of oil sorption and decreased the water sorption. The maximum oil sorption was observed for the material treated at 18$0^{\circ}C$for 60 min. The amount of hydrogen cyanide from the combustion were 0.09ml/g, 0.07ml/g for pine leaves and straw respectively meaning that the final disposal by combustion might be feasible. The amount or organic carbon extracted from pine leaves during 7 days was up to 0.015g organic carbon from one gram of pine leaves. but the degradation was as fast as for glucose. It is concluded that the pine leaves can be served as a good raw material for the powdered oil absorbent like peat moss.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.6
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• pp.551-560
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• 2011

In this paper, a cooling system that includes a heat spreader and a natural convective heat sink is proposed for the cooling of a concentrating photovoltaic (CPV) module. The heat spreader and the natural convective heat sink are designed on the basis of previous analytical investigations. In order to evaluate the proposed cooling system, we conducted experimental investigations varying the heat rate and the inclined angle of the cooling system. From the experimental results, it is found that the proposed cooling system satisfies the design constraints for good operation of the CPV module. Finally, a correlation is suggested for estimating the effects of the heat rate and the inclined angle on the thermal performance of the natural convective heat sink is suggested.

• Composites Research
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• v.33 no.4
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• pp.213-219
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• 2020

Recently, global facing environmental issues have been raised caused by plastic waste. Hence, increasing the demand for interest in environmentally friendly materials. In this row, research on engineering composite materials also replacing the synthetic reinforcement by introducing natural fibers. However, focus on the strength and interfacial adhesion between matrix and reinforcement is very essential in natural fiber composite, which is insufficient in the literature. There are number of approaches for improving the mechanical strength of the composites, one of the common methods is to reinforce additive nanoparticles. The present investigation, bio-additives were synthesized utilizing bio-waste, cheap, bio-degradable sea-weed powder that could replace expensive nanomaterials and reinforced into the CFRP composite through Hand lay-up followed by a vacuum process. Mechanical properties were evaluated and analyzed through microanalysis. The results concluded that synthesized additives are effective for improving mechanical properties such as tensile, flexural, impact, and shear strength. Overall, the results confirmed that the fabricated composites have potential applications in the field of engineering applications.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.12
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• pp.149-156
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• 2019

Recently, skyscraper building and apartment fires, which were rapidly spread out from a low floor to a rooftop, have become a frequent occurrence in mass media. This fire problems have a fatal disadvantage that the exterior wall finish of the building emits toxic gas in case of fire by using dry bit method or organic insulating material. Therefore, in order to remedy these problems, many exterior wall finishing construction methods have been proposed, but the current trend is to use existing construction methods due to problems such as economy, weight, and durability. On the other hand, in countries such as Germany and Japan, ceramic sidings are used as exterior finishing material for buildings, which is environmentally friendly, excellent natural beauty, long life, easy maintenance and high-quality exterior materials. However, those ceramic sidings have still the problems such as manufacturing cost and weight problem because of boosting the sintering temperature up to 1,350℃ or more. Also, conventional CRC, MgO, FRP sidings which are composed of pulp, glass fiber and organic materials, have been reports of deformation due to ultraviolet rays, discoloration, corrosion and scattering, surface rupture, lifting and peeling. Therefore, in this study as an alternative to solve this problem, halosite nano kaolin produced in Sancheong in Korea and frit flux were used to satisfy the required properties as ceramic siding using low temperature sintering (below 1,000℃) and lightweight materials such as pearlite. This study aims to design the optimal formulation and process of materials and to study the characteristics of nano-coated ceramic siding material development and to present relevant basic data. The findings show that ceramic siding for nanocoated building materials is excellent as a natural ceramic siding building material. The fire resistance of natural minerals and nano particle refining technology satisfy the bending strength of 80kgf / cm2, the volume ratio of 2.0 and the absorption rate of less than 10.0%.

• Korean Journal of Materials Research
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• v.34 no.5
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• pp.223-234
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• 2024

This review explores the potential of pillared bentonite materials as solid acid catalysts for synthesizing diethyl ether, a promising renewable energy source. Diethyl ether offers numerous environmental benefits over fossil fuels, such as lower emissions of nitrogen oxides (NO_x) and carbon oxides (CO_x) gases and enhanced fuel properties, like high volatility and low flash point. Generally, the synthesis of diethyl ether employs homogeneous acid catalysts, which pose environmental impacts and operational challenges. This review discusses bentonite, a naturally occurring alumina silicate, as a heterogeneous acid catalyst due to its significant cation exchange capacity, porosity, and ability to undergo modifications such as pillarization. Pillarization involves intercalating polyhydroxy cations into the bentonite structure, enhancing surface area, acidity, and thermal stability. Despite the potential advantages, challenges remain in optimizing the yield and selectivity of diethyl ether production using pillared bentonite. The review highlights the need for further research using various metal oxides in the pillarization process to enhance surface properties and acidity characteristics, thereby improving the catalytic performance of bentonite for the synthesis of diethyl ether. This development could lead to more efficient, environmentally friendly synthesis processes, aligning with sustainable energy goals.

• Journal of the Korean Society of Clothing and Textiles
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• v.32 no.5
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• pp.741-752
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• 2008

The purposes of this study are to review the status of dress material in the contemporary fashion design by examining the intertextuality of many materials other than textiles used in the contemporary fashion and to show that the development of new fashion materials is a factor for designing competitiveness. The results of this study are summarized as follows: First, foods and natural objects are used as fashion materials to reveal natural beauty, and at the same time new formative elements are expressed in combinations of life and fashion. Second, common paper and luxurious jewelry are presented as a formative element symbolic of an aspect of the contemporary society or embodied in elaborate handicraft techniques. Those materials boost the luxuriousness of costume and create a strong futuristic image according to how they are expressed. Third, plastics available for a variety of objects in different shapes and colors offer such formative features that could be shaped with textiles, as high-end technology is introduced to fashion. Fourth, metallic materials have added freedom to design formality due to their qualities of convergence and displacement and by the introduction of brand-new technology, suggesting a new future for the fashion industry. Fifth, using a variety of anti-fashion materials including semiconductor chips, mirrors, vinyl, wires, and rubber makes a change in the existing points of view regarding the formality of things and helps create a special aesthetic effect in a visual respect to develop a strong intertextuality of materials.

• Journal of Food Hygiene and Safety
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• v.27 no.3
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• pp.257-263
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• 2012

Cosmetics using natural materials which was purchased in retail stores, distributed in Gyeonggi province(32 samples) and online through internet(24 samples) were analyzed by pesticide residues and target preservatives for assessing the safety of it. Natural or organic certifications was identified in 22 samples among 56 samples and most of them were Ecocert. Pesticide residues was detected in 3 samples among 56 samples and each compound and concentration was permethrin(0.6 mg/kg), tricyclazole(11.7 mg/kg) and malathion(0.05 mg/kg). All of it was purchased through internet. Target preservatives was detected in 13 samples among 56 samples and one of them was over the maximum allowed concentration and the rest of them were within the maximum allowed concentration of the respective preservatives. The compound which was over the maximum allowed concentration was benzoic acid and compounds which were within the maximum allowed concentration were sorbic acid, benzoic acid and methylparaben. They were all identified substances in products and the number of detected preservatives in retail stores were higher than online samples purchased through internet. As a result of this study, The method of analyzing pesticide residues and limit in cosmetics using natural materials should be set up as soon as possible and the monitoring about preservatives in cosmetics using natural materials should be conducted on continuously.

• Journal of the Korean Applied Science and Technology
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• v.38 no.1
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• pp.107-117
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• 2021

The purpose of this study is to provide basic data for the development of UV protection products using natural materials. The research method is investigation and analyzation of the current status of the domestic and foreign industries, natural material research trends, and patent status of skin care-related sunscreen. As the result of the study, the U.S. market for sunscreen is the largest one, accounting for about 21% of the world, and the Chinese market is rapidly growing. The top four major types of functional cosmetics in Korea are complex functional products, followed by wrinkle improvement, sunscreen and whitening, and both the global and domestic markets continue to grow continuously. Over the past decade, research trends in natural sunscreen materials have shown that Scutellaria baicalensis, Humulus lupulus L., licorice, Finger root, Green tea, lespedeza cuneata extracts are effective, and in addition, they are also effective in photo-aging, antioxidant, anti-inflammatory, antibacterial, whitening, and wrinkle improvement. The patent registration status is on the rise and the ingredients were secured from plants and seaweeds. As the conclusion of this research, It is expected that natural UV protection material will be able to be used as multi-functional cosmetics material by developing safe and proven natural materials in line with future global trends.

• Proceedings of the Korean Society of Crop Science Conference
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• 2002.05a
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• pp.28-37
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• 2002