• Journal of Powder Materials
• /
• v.22 no.4
• /
• pp.278-282
• /
• 2015

The GaN-powder scrap generated in the manufacturing process of LED contains significant amounts of gallium. This waste can be an important resource for gallium through recycling of scraps. In the present study, the influence of annealing temperatures on the structural properties of GaN powder was investigated when the waste was recycled through the mechanochemical oxidation process. The annealing temperature varied from $200^{\circ}C$ to $1100^{\circ}C$ and the changes in crystal structure and microstructure were studied. The annealed powder was characterized using various analytical tools such as TGA, XRD, SEM, and XRF. The results indicate that GaN structure was fully changed to $Ga_2O_3$ structure when annealed above $900^{\circ}C$ for 2 h. And, as the annealing temperature increased, crystallinity and particle size were enhanced. The increase in particle size of gallium oxide was possibly promoted by powder-sintering which merged particles to larger than 50 nm.

• Fashion & Textile Research Journal
• /
• v.10 no.6
• /
• pp.1045-1050
• /
• 2008

Developing of high technology, productivity of the fiber product has being rapidly increased and also various kinds of advanced treatment process lead consumer's needs to more high functional, clean and healthy goods. Moreover, increasing in the concern of eco-friendly material and processing, it has been getting popular that the dyeing method like as using natural dyes is more eco-friendly and natural-friendly treatment process. The method, used in this study, adhesion by binding with micro-capsulized natural material to fabric has low change in quality by external influence and high ability in spray effect by broken capsule which comes to pressure and friction when it dressed. Also it has wide application from natural fiber to synthetic fiber. The purpose of this study is development of multi-functional synthetic material with micro-capsulized Scutellaria baicalensis on PET. Moreover, it was driven by comparison of colormetric properties and fastness between regular dip-dyeing method and binding with micro-capsulized material method. Dye ability was arranged mostly low exhaustion but the PET treated by micro-capsule was more or less better than the dip-dyeing PET. Through the SEM(Scanning Electron Microscope) of PET treated by micro-capsule, it has good residence of capsules even after 5 or 10 times washing. Wash and light fastness was arranged some different grade by each condition but mostly high achievement and the micro-capsulized PET was more improved than regular dip-dyed PET.

• Korean Journal of Materials Research
• /
• v.27 no.9
• /
• pp.459-465
• /
• 2017

Nano-sized Zinc selenide (ZnSe) powder was successfully synthesized using Zn and Se precursors in a hydrothermal process. Temperature for the synthesis was varied from $95^{\circ}C$ to $180^{\circ}C$ to evaluate its influence on the microstructural properties of the synthetic particles. ZnSe powder thus fabricated was characterized using various analytical tools such as SEM, XRD, TEM and UV-Vis methods. Two types of ZnSe particles, that is, the precipitated particle and the colloidal particles, were identified in the analysis. The precipitated particles were around 100 nm in average size, whereas the average size of the colloidal particles was around 20 nm. The precipitated particles made at $150^{\circ}C$ and $180^{\circ}C$ were found to be a single phase of ZnSe; however, an inhomogeneous phase was obtained at the lower synthesis temperature of $95^{\circ}C$, suggesting that the temperature for the synthesis should be over $100^{\circ}C$. The precipitated particles were inactive in the UV-Vis absorption investigation, whereas the colloidal particles showed that absorptions occurred at 380 nm in the UV-Vis spectrum.

• Korean Journal of Environment and Ecology
• /
• v.20 no.1
• /
• pp.1-8
• /
• 2006

The objective of this study was to monitor the regenerated process of natural vegetation on the rear-slope of Jangheung multi-purpose dam using the recycling eco-revegetation technique. The monitoring plots were established in May 2004 and the plots were monitored in May 2004 and October 2005. Flora, plant community structures, naturally introduced plants, death rates were monitored. The change of flora after wood chip mulching decreased in family and species, but the influence of vine tree was extended. The urbanization index declined. Naturally introduced species and death ratios at the monitoring plot had a tendency to a higher increase in the deciduous broad-leaved forest.

• Corrosion Science and Technology
• /
• v.20 no.1
• /
• pp.15-21
• /
• 2021

Through a simple filtration process, followed by carbonization within a reductive environment, coffee waste grounds can be transformed into a non-porous hard carbon for use in multiple contexts. This resulting coffee-waste carbon has been evaluated as an eco-friendly and cost-effective replacement for conventional graphite. When compared with different types of carbon, our study found that the coffee-waste carbon fell into the category of hard carbon, as verified from the galvanostatic charge/discharge profiles. The coffee-waste carbon showed a superior rate capability when compared to that of graphite, while compromising smaller capacity at low C rates. During electrochemical reactions, it was also found that the coffee-waste carbon is well exposed to electrolytes, and its disordered characteristic is advantageous for ionic transport which leads to the low tortuosity of Li ions. Finally, the high irreversible capacity (low initial Coulombic efficiency) of the coffee-waste carbon, which if also often observed in amorphous carbon, can be adequately resolved through a solution-based prelithiation process, thereby proving that the coffee-waste carbon material is quite suitable for commercial use as an anode material for quickly-chargeable electrodes.

• Korean Journal of Materials Research
• /
• v.31 no.8
• /
• pp.445-449
• /
• 2021

Zintl compound Mg₃Sb₂ is a promising candidate for efficient thermoelectric material due to its small band gap energy and characteristic electron-crystal phonon-glass behavior. Furthermore, this compound enables fine tuning of carrier concentration via chemical doping for optimizing thermoelectric performance. In this study, nominal compositions of Mg_3.8Sb_2-xTe_x (0 ≤ x ≤ 0.03) are synthesized through controlled melting and subsequent vacuum hot pressing method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) are carried out to investigate phase development and surface morphology during the process. It should be noted that 16 at. % of excessive Mg must be added to the system to compensate for the loss of Mg during melting process. Herein, thermoelectric properties such as Seebeck coefficient, electrical conductivity, and thermal conductivity are evaluated from low to high temperature regimes. The results show that Te substitution at Sb sites effectively tunes the majority carriers from holes to electrons, resulting in a transition from p to n-type. At 873 K, a peak ZT value of 0.27 is found for the specimen Mg_3.8Sb_1.99Te_0.01, indicating an improved ZT value over the intrinsic value.

• Journal of East Asia Management
• /
• v.2 no.1
• /
• pp.63-92
• /
• 2021

Human activities have been putting a great burden on the earth, leading to many serious problems, such as lack of resources, ecological degradation and air degradation. Although many countries have recognised this circumstance and have developed some sustainable development strategies, the earth still needs research on sustainability in different views and various industries. The nursing industry has grown with the ageing of the global population in recent years, and professional nursing institutions could relieve structural deterioration caused by the ageing population in family, social, economic and cultural. Hence, exploring the key criteria of organisational sustainability in the nursing industry is of the utmost priority. This paper puts forward an evaluation framework to identify the key criteria of organisational sustainability. After connections with nursing homes A and B in China, the author adopts literature research to confirm the criteria system which is based on triple bottom line, utilises analytical network process method to design the network hierarchy analysis model and importance comparison questionnaires to collect experts' first-hand data, and uses technical software - Super Decisions to integrate data and obtain final results. The results recommend three top-ranked criteria in the entire system, eco-recruitment, eco-procurement and corporate social responsibility are discussed with some professional suggestions in the end. The limitations are also extended in the last chapter to provide future research perspectives.

• Korean Journal of Materials Research
• /
• v.32 no.6
• /
• pp.287-292
• /
• 2022

Magnesium-antimonide is a well-known zintl phase thermoelectric material with low band gap energy, earth-abundance and characteristic electron-crystal phonon-glass properties. The nominal composition Mg_3.8-xZn_xSb₂ (0.00 ≤ x ≤ 0.02) was synthesized by controlled melting and subsequent vacuum hot pressing method. To investigate phase development and surface morphology during the process, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were carried out. It should be noted that an additional 16 at. % Mg must be added to the system to compensate for Mg loss during the melting process. This study evaluated the thermoelectric properties of the material in terms of Seebeck coefficient, electrical conductivity and thermal conductivity from the low to high temperature regime. The results demonstrated that substituting Zn at Mg sites increased electrical conductivity without significantly affecting the Seebeck coefficient. The maximal dimensionless figure of merit achieved was 0.30 for x = 0.01 at 855 K which is 30% greater than the intrinsic value. Electronic flow properties were also evaluated and discussed to explain the carrier transport mechanism involved in the thermoelectric properties of this alloy system.

• Korean Journal of Materials Research
• /
• v.33 no.11
• /
• pp.482-490
• /
• 2023

The purpose of this study was to analyze microstructural changes and evaluate the mechanical properties of TWIP steel subjected to variations in heat treatment, in order to identify optimal process conditions for enhancing the performance of TWIP steel. For this purpose, a homogenization heat treatment was conducted at 1,200 ℃ for 2 h, followed by hot rolling at temperature exceeding 1,100 ℃ and cold rolling. Annealing heat treatment is achieved using a muffle furnace in the range of 600 ℃ to 1,000 ℃. The microstructure characterization was performed with an optical microscope and X-ray diffraction. Mechanical properties are evaluated using micro Vickers hardness, tensile test, and ECO index (UTS × Elongation). The specimens annealed at 900 ℃ and 1,000 ℃ experienced a significant decrease in hardness and strength due to decarburization. Consequently, the decarburization phenomenon is closely related to the heat treatment process and mechanical properties of TWIP steel, and the effect of the microstructure change during annealing heat treatment.

• Journal of the Korea Furniture Society
• /
• v.25 no.4
• /
• pp.345-352
• /
• 2014

This study was carried out to develop eco-friendly wood street lamp (EFWSL) by using wood resources stacked in the forests after tree tending operations which were mostly abandoned, but economical as renewable wood resources for developing the wood coated street lamps with the effects of cost reduction and their attractive appearances. This study has led to the development of key compact structures of street-lighting wood poles (shaft) using laminated timber. The core technique in this study is related with producing the more stable wood poles (shaft) with the hole inside than wood poles exposed under the natural environment through applicable process to protect the wood from bursting and splitting. We also comprehensively developed the method to conserve the timber durability of wood shaft and connect the wood shaft with groove, race way to be located in the groove, locking ring, current stabilizer connected to the groove and luminaire support arm, base and hand-hole which was partly used in combination with steel materials and wood. Also we increased the utilization of abandoned and stacked woods after thinning in the forests such as Pinus densiflora, Larix leptolepis, and Pinus koraiensis plantations by maximizing the value of these natural wood resources as main materials of eco-friendly street lightings with the effects of cost reduction and attractive appearances and also the expectation of advertising effects of street lightings developed in this study.