• Membrane Journal
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• v.32 no.5
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• pp.292-303
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• 2022

An eco-friendly energy conversion device without the emission of pollutants has gained much attention due to the rapid use of fossil fuels inducing carbon dioxide emissions ever since the first industrial revolution in the 18th century. Polymer electrolyte membrane fuel cells (PEMFCs) that can produce water during the reaction without the emission of carbon dioxide are promising devices for automotive and residential applications. As a key component of PEMFCs, polymer electrolyte membranes (PEMs) need to have high proton conductivity and physicochemical stability during the operation. Currently, perfluorinated sulfonic acid-based PEMs (PFSA-PEMs) have been commercialized and utilized in PEMFC systems. Although the PFSA-PEMs are found to meet these criteria, there is an ongoing need to improve these further, to be useful in practical PEMFC operation. In addition, the well-known drawbacks of PFSA-PEMs including low glass transition temperature and high gas crossover need to be improved. Therefore, this review focused on recent trends in the development of high-performance PFSA-PEMs in three different ways. First, control of the side chain of PFSA copolymers can effectively improve the proton conductivity and thermal stability by increasing the ion exchange capacity and polymer crystallinity. Second, the development of composite-type PFSA-PEMs is an effective way to improve proton conductivity and physical stability by incorporating organic/inorganic additives. Finally, the incorporation of porous substrates is also a promising way to develop a thin pore-filling membrane showing low membrane resistance and outstanding durability.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.1061-1070
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• 2023

Over the last few years, lead-free inorganic metal perovskites have gained impressive ground in empowering satellites in space exploration owing to their material stability and performance evolution under extreme space environments. The present work has examined the versatility of eight such perovskites as space radiation shielding materials by computing their photon, charged particles and neutron interaction parameters. Photon interaction parameters were calculated for a wide energy range using PAGEX software. The ranges of heavy charged particles (H, He, C, N, O, Ne, Mg, Si and Fe ions) in these perovskites were estimated using SRIM software in the energy range 1 keV-10 GeV, and that of electrons was computed using ESTAR NIST software in the energy range 0.01 MeV-1 GeV. Further, the macroscopic fast neutron removal cross-sections were also calculated to estimate the neutron shielding efficiencies. The examined shielding parameters of the perovskites varied depending on the radiation type and energy. Among the selected perovskites, Cs₂TiI₆ and Ba₂AgIO₆ displayed superior photon attenuation properties. A 3.5 cm thick Ba₂AgIO₆-based shield could reduce the incident radiation intensity to half its initial value, a thickness even lesser than that of Pb-glass. Besides, CsSnBr₃ and La_0.8Ca_0.2Ni_0.5Ti_0.5O₃ displayed the highest and lowest range values, respectively, for all heavy charged particles. Ba₂AgIO₆ showed electron stopping power (on par with Kovar) better than that of other examined materials. Interestingly, La_0.8Ca_0.2Ni_0.5Ti_0.5O₃ demonstrated neutron removal cross-section values greater than that of standard neutron shielding materials - aluminium and polyethylene. On the whole, the present study not only demonstrates the employment prospects of eco-friendly perovskites for shielding space radiations but also suggests future prospects for research in this direction.

• Journal of the Korean Society of Radiology
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• v.11 no.5
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• pp.297-302
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• 2017

Recently, building materials and air purification filters with eco-friendly charcoal are actively studying to reduce the concentration of radon gas in indoor air. In this study, radon reduction performance was assessed by designing and producing new panel-type activated carbon filter that can be handled more efficiently than conventional charcoal filters, which can reduce radon gas. For the fabrication of our panel-type activated carbon filter, first the pressed molding product after mixing activated carbon powder and polyurethane. Then, through diamond cutting, the activated carbon filter of 2 mm, 4 mm and 6 mm thickness were fabricated. To investigate the physical characteristics of the fabricated activated carbon filter, a surface area and flexural strength measurement was performed. In addition, to evaluate the reduction performance of radon gas in indoor, the radon concentration of before and after the filter passes from a constant amount of air flow using three acrylic chambers was measured, respectively. As a result, the surface area of the fabricated activated carbon was approximately $1,008m^2/g$ showing similar value to conventional products. Also, the flexural load was found to have three times higher value than the gypsum board with 435 N. Finally, the radon reduction efficiency from indoor gas improved as the thickness of the activated carbon increases, resulting in an excellent radon removal rate of more than 90 % in the 6 mm thick filter. From the experimental results, the panel-type activated carbon is considered to be available as an eco-friendly building material to reduce radon gas in an enclosed indoor environment.

• Journal of Korean Home Economics Education Association
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• v.26 no.3
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• pp.91-112
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• 2014

The purpose of this study is to analyze how the elements of activating happiness education suggested by Noddings is reflected in the Home Economics part of Middle School Technology-Home Economics Textbook Volume 2 of 2009 Curriculum Revision. The introduction style of unit, sub-unit, and small chapter, the objectives, the body contents, the activity resources, the tables/diagrams/pictures, the supplementry and advancedl materials, and the wrap-up and evaluation of sub-unit and units of Home Economics part of Technology Home Economics textbook volume 2 were analyzed. Noddings suggested the elements for activating happiness education in five areas of personal life sector including 'home making', 'place and nature', 'parenting', 'chracter and spiriual experiences', and 'growth of interpersonal relationships' and two areas of public one including 'preperation for work' and 'community, democracy and voluntary activities'. The specific elements in seven sectors of activating happiness education were extracted using the content analysis. How the elements of those suggested by Noddings were reflected in the various parts of the textbook were analyzed in terms of the closeness of approaches, contents, and procedures between Noddings's and textbook. The major findings of this study were as follows: 1. The degree to which the elements of activating happiness education were reflected in the textbook differed by each unit. The elements of activating happiness education were reflected the most frequently in the unit of 'Unit of Practice of Eco-friendly Family Life' and the least frequently in the unit of 'Unit of Career and Life Planning'. 2. The Home Economics units of Technology Home Economics textbooks 1&2 reflects the factors of personal life and public life that Noddings suggested for activating happiness. However, personal life-related factors are relatively more reflected in the units than the public life-related factors. 3. Although the elements of activating happiness education were generally reflected in all the elements of a textbook, these elements were relatively more reflected in the Unit Introduction, Sub-unit Introduction, Chapter and Introduction, Objectives, body contents and tables/diagrams/pictures.

• Journal of Korean Home Economics Education Association
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• v.26 no.3
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• pp.35-52
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• 2014

This study analyzed the 12 different technology home economics textbooks I, II for middle school students and the content systems of the textbooks by 7 instructional strategies in Reigeluth's elaboration theory. The units analyzed were 'Clothing and self-expression' and 'Eco-friendly clothing life and recycling by reform'. The purpose of this study was to provide basic information for the development of textbooks and teaching materials by analyzing current textbooks. Researchers analyzed the textbooks individually using pre-developed analysis frame using Reigeluth's elaboration theory. The results of the study were as follows. The conceptual elaboration process was used in the unit of 'Clothing and self-expression' of all the textbooks used in this study, and procedural elaboration process was mostly used in the unit of 'Eco-friendly clothing life and recycling by reform'. The strategies of advance learning ability were presented mostly in the forms of 'Learning Objective', 'Thought Opening', 'Key terms' in either unit and sub unit. The strategies of summarizer were presented as 'Unit Summary', 'Cleanup' and 'Assessment'. The strategies of synthesizer were used in all the textbooks as the 'Exploration' to increase the students interest through the promotion of the learning content in a variety of activities and projects. The cognitive activator strategies were shown in all of the textbooks using mostly 'Figure,' and others such as 'Table,' 'Diagram', and 'Explanation of Terms'. The strategies of learner control were used to guide the supplement and deepen the learning by various forms. However the analogy strategies were hardly used in units of textbooks analyzed in this study. As a result, the technology home economics textbooks I, II for middle school students applied the Reigeluth's elaboration theory, except the analogy strategies. It is recommended to utilize th analogy strategies and various activities to enhance the students' understanding and participation.

• Journal of agriculture & life science
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• v.44 no.5
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• pp.1-8
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• 2010

In this study, eco-friendly hybrid composite boards were manufactured from green tea and wood fibers for application as interior materials with various functionalities of green tea and strong strength properties of wood fibers. In this relation, the effect of green tea content on the static bending strength performances of these green tea and wood fibers composite boards were investigated. Static bending strengths of hybrid composite boards were lower than those of control boards and decreased with the increase of green tea content. Also, the strength performances appeared to be somewhat different by resin type used for board manufacture. The hybrid composite boards manufactured from $E_1$ grade urea resin adhesive, which has higher molar ratio of formaldehyde to urea than that of $E_0$ grade one, were 1.08~1.53 times higher in bending modulus of elasticity (MOE) and 1.19~1.82 higher in modulus of rupture (MOR) than that manufactured from $E_0$ grade. And, the differences of MOE and MOR between hybrid composite boards manufactured from $E_0$ grade and $E_0$ grade urea resin adhesive increased with the increase of green tea content. In the case of hybrid composite boards manufactured from $E_1$ grade urea resin adhesive, the MOR was within 0.94~1.03 times the commercial medium density fiberboard. Thus, it was thought that eco-friendly hybrid composite boards with various functionalities and strong strength performances could be manufactured from green tea and wood fibers.

• Journal of agriculture & life science
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• v.53 no.5
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• pp.127-136
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• 2019

Today, as the specification of pigs increases, it is important to develop eco-friendly livestock feeds that do not add antibiotics to highly utilizable materials as feed resources, and to produce functional eco-friendly pork and processed products. The purpose of this study was to establish Rubus occidentalis (RO) byproducts containing various amounts of physiologically active substances such as anticancer, anti - inflammation and antioxidant as a raw material for pig feed. The multifaceted efficacy of the RO fermented fodder (ROFF) was confirmed by the nutrient transport factors and antioxidant activity of Berkshire pigs. ROFF was added 0.3% to the general diet and the efficacy was confirmed by feeding diets to Berkshire pigs according to each weight for 43~73 days. As a result, the total cholesterol (TC), LDL-cholesterol (LDL-C) and HDL-cholesterol (HDL-C) levels were decreased or were increased in the castrated male and female Berkshire pigs but not significantly. It was confirmed that the tendency was improved in nutrition physiology. The biochemical levels of female finishing pigs were not significant but increased. In the case of finishing pigs with possibility of pregnancy, it is expected that the nutrition supply for piglet production and will help in the production of the healthy piglet. Transferrin (TFE) levels tended to increase in female growing pig and 110-150 kg finishing pigs. Thus ROFF could minimize the negative effects of iron contents deficiency in female Berkshire pigs. Glutathione peroxidase 1 (GPx1) activity was increased in castrated male and female 110-150 kg finishing pigs. Therefore, ROFF tends to improve the antioxidant capacity. The results of this study suggest that ROFF is one of the most favorable dietary sources when considering the contents of RO in feed. In particular, ROFF could have a positive effect on nutrient transport and iron content of female rather than castrated male Berkshire pigs.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.19 no.3
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• pp.125-131
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• 2013

In order to protect agricultural products against damage by physical load, various shock absorbing materials is used. As the demands of environment protection increase, the use of plastic materials have been restricted. On the other hand, Pulp mold products have some benefits - easy manufacturing, superior shock absorbing and eco-friendly. In order to develop pulp mold tray for melon packaging as shock absorbing packaging material, we investigated physical properties and vibration transmission characters of 180, 200 and 220 g pulp mold tray for melon. As the weight of pulp increased, compression strength and shock absorbing performance increased, while vibration transmissibility decreased. Especially in case of 180g pulp mold tray, it is not suitable for melon packaging because the transmitted vibration acceleration was higher than the forced vibration acceleration. And 200g pulp mold tray is suitable for melon packaging because the vibration transmissibility was lowest in three trays. And the vibration acceleration transmitted to the melon in edge of pulp mold tray was higher than to the melon in center of pulp mold tray. As the result of the simulated transportation test, the firmness of melon packaging using pulp mold tray was higher than that of conventional packaging. Therefore, these results suggest that pulp mold tray packaging could be suitable for melon packaging.

• Clean Technology
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• v.26 no.3
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• pp.177-185
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• 2020

All coal ash, generated from coal-fired power plants, is entirely dumped onto a landfill site. As coal ash contains 80% fly ash, a clean floating process was developed in this study to recover useful components from coal ash and to use them as high value-added industrial materials. When the unburned carbon (UC) was recovered from the fly ash, soybean oil, an eco-friendly vegetable oil, was used as collector instead of a non-ionic kerosene collector to prevent the occurrence of odor from the kerosene. After the UC was separated by flotation, particulate ceramic microsphere (CM) was recovered, without generating acidic wastewater, through hydro-cyclone instead of sulfuric acid solution in order to separate ceramic microsphere (CM) and cleaned ash (CA) from the residue. By utilizing soybean oil as a collector, the recovery rate of UC turned high at 85.8% due to the increased adsorption of UC, the high viscosity of soybean oil, and the increase in floating properties caused by the linoleic acid contained in soybean oil. All of the combustible components contained in the recovered UC were carbon components, with the carbon content registering high when soybean oil was used. The recovered UC had many pores with a rough surface; thus, it could be easily ground and then used as an industrial material for its fine particles. The CM and CA recovered by the clean separation process using hydro-cyclone had a spherical shape, and the particles were clearly separated without clumping together. The average diameter (D₅₀) of the particles was 5 ㎛, so it was possible to realize the atomization of CM through a process change.

• Korean Journal of Environment and Ecology
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• v.30 no.1
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• pp.92-97
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• 2016

The purpose of this study was to improve growth and survival rate of marine microalgae and macroalga zoospores using with eco-friendly capsulation materials. The capsulation materials were chosen an alginic acid which extracted from marine brown algae combining with starch and calcium chloride. The capsulated microalgae, Nannochloropsis salina and macroalga zoospores, Ulva australis were evaluated with growth and survival rate. When the mixed ratio of alginic acid was less than 50%, capsule formation was not performed. When the ratio of 50% alginic acid and 50% starch, the microalgae was shown the highest growth and survival rate increasing up to $8.74{\times}10^5cells\;mL^{-1}$ while 100% of alginic acid was the lowest rate up to $4.92{\times}10^5cells\;mL^{-1}$. The increasing starch ratio improved to their growth and survival rate, however decreasing alginic acid make physical capsule formation weaken. By applying on a surface of artificial reef, capsulated algal zoospores were germinated 99 individuals $cm^{-2}$. This attempt will be provided to basic core technology for marine afforestation in coastal area.