• Korean Journal of Materials Research
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• v.31 no.1
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• pp.54-59
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• 2021

In this work, narrow-band green-emitting CsPbBr3 particles are embedded in commercialized glass composites by a facile dry process. By optimizing the method through sintering in glass frit (GF) composites including CsBr and PbBr2, used as precursors, the encapsulation of CsPbBr3 particles made them waterproof with green fluorescence. To improve the fluorescent properties by reducing aggregation of CsPbBr3, fumed silica (FS) is additionally used to help particles avoid bulking up in the glass matrix. The CsPbBr3 perovskite/glass composites are characterized using scanning electron microscopy (SEM) images and energy-dispersive X-ray spectroscopy (EDS) maps, which support the existence of CsPbBr3 particles in the glass matrix. The photoluminescence (PL) properties demonstrate that the emission spectrum peak, full width at half maximum (FWHM), and photoluminescence quantum yield (PLQY) values are 519 nm, 17 nm, and 17.7 %. We also confirm the water-resistant properties. To enhance water/moisture stability, the composite sample is put directly into water, with its PLQY monitored periodically under UV light.

• Journal of Animal Science and Technology
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• v.55 no.5
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• pp.483-488
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• 2013

To develop a sustainable composting method for livestock mortality, a natural aeration-composting process was designed and the influences of bulking materials on the mortality composting process were studied. Bulking materials (e.g., compost, swine manure, sawdust, and rice husks), easily supplied at the scene of an animal mortality outbreak, were tested in this research. A lab-scale composting system (W34 ${\times}$ L60 ${\times}$ H26 cm) was made using 100 mm styrofoam, and natural aeration was achieved through pipes installed on the bottom of the system. Four treatments were designed (compost, compost + swine feces, sawdust, and rice husks treatment groups) and all experiments were done in triplicates. During composting for 40 days, no leachate was observed in compost and sawdust treatment groups, whereas 18 and 8.2 ml leachate/kg-mortality was emitted from the compost + feces and rice husks treatment groups, respectively. Dimethyl disulfide (DMDS) emission during the composting was very low in all treatment groups, possibly due to the bio-filtering function of the compost cover layer on the pile. The mortality degradability in compost, compost + feces, sawdust, and rice husks groups was 25.3, 25.8, 13.5, and 14.5%, respectively, showing significantly higher levels in compost and compost + feces groups (p<0.05). Also, only the compost + feces group produced enough heat (over $55^{\circ}C$) and lasted for 7 days, indicating that bio-security cannot be guaranteed without feces supplementation.

• Journal of Bio-Environment Control
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• v.2 no.1
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• pp.16-26
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• 1993

A sundry system is one of popular systems for composting livestock manure, of which main honest is to utilize unlimited, clean, and free solar radiation. A sundry system with a composter of two horizontal screw-type concrete ducts at different height, was constructed and operated for three days for each test in May, 1993, to evaluate its composting performance. Four treatments of the mixture ratio of swine manure and saw dust (manure : sawdust= 1 : 1.25, 1 : 1, 1 : 0.7, 1 : 0.5) were implemented to evaluate the effect of the mixture ratio on degradation of the composting materials of a sundry system with a screw-type composter. Maximum temperature of the composting materials was over 5$0^{\circ}C$ at D1 or D2 (one or two days after operation starts) for each test. Mean C/N ratio and water contents of the materials were reduced by more than 15 and 20％, respectively. Microbial density of each test showed a typical variation with the lapse of the composting time. Mesophilic microorganism seemed to play more important role on degradation of the materials than thermophilic. A sundry system with a screw-type composter can be considered as a feasible system on basis of maturity data. The conclusion was completely reverse from that of Choi et at., although both adopted a sundry system. A further study is recommended to pursue the cause of better performance of the screw-type composter, whether it was due to affirmative weather or more efficient composter.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.5
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• pp.753-758
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• 2016

Moisture content influences physiological characteristics of microbes and physical structure of solid matrices during composting of animal manure. If moisture content is maintained at a proper level, aerobic microorganisms show more active oxygen consumption during composting due to increased microbial activity. In this study, optimum moisture levels for composting of two bedding materials (sawdust, rice hull) and two different mixtures of bedding and beef manure (BS, Beef cattle manure+sawdust; BR, Beef cattle manure+rice hull) were determined based on oxygen uptake rate measured by a pressure sensor method. A broad range of oxygen uptake rates (0.3 to 33.3 mg $O_2/g$ VS d) were monitored as a function of moisture level and composting feedstock type. The maximum oxygen consumption of each material was observed near the saturated condition, which ranged from 75% to 98% of water holding capacity. The optimum moisture content of BS and BR were 70% and 57% on a wet basis, respectively. Although BS's optimum moisture content was near saturated state, its free air space kept a favorable level (above 30%) for aerobic composting due to the sawdust's coarse particle size and bulking effect.

• Journal of Environmental Health Sciences
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• v.28 no.5
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• pp.22-27
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• 2002

The composting practice has been recognized as the most popular way of controlling food waste and many attempt have been made in the field to establish more efficient and economical process. Some of the efforts are mixing cured compost with sawdust as alternative bulking agent, seeding commercially produced microorganism and/or combination of above. However, verification of such efforts is often restricted because of either the lack of engineering consideration on the limitation of composting facility scales. In this study, the effect of mixing materials in food waste composting was investigated by controlling the combination and the mixing ratio of them. When the cured compost was mixed with saw dust. the decomposition of organic material was proven to be more active by observing the compost temperature, the oxygen (O$_2$) consumption, and the cumulative carbon dioxide ($CO_2$) profile. However, the quantity of compost mix-ing seemed not to influence the reaction as long as the minimum required amount was mixed. The feeding of com-mercially produced microorganism had a tendency to prolong the thermophilic stage, which helped to increase the decomposition but it resulted in composting period. Regardless of the composting condition, bacteria and actinomycetes increased in population as the reaction approached to the end. The population of bacteria and actinomycetes were rel-atively higher than those of fungi and yeast throughout the reaction.

• Structural Engineering and Mechanics
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• v.74 no.2
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• pp.175-187
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• 2020

The theories having been developed thus far account for higher-order variation of transverse shear strain through the depth of the beam and satisfy the stress-free boundary conditions on the top and bottom surfaces of the beam. A shear correction factor, therefore, is not required. In this paper, the effect of surface on the axial buckling and free vibration of nanobeams is studied using various refined higher-order shear deformation beam theories. Furthermore, these theories have strong similarities with Euler-Bernoulli beam theory in aspects such as equations of motion, boundary conditions, and expressions of the resultant stress. The equations of motion and boundary conditions were derived from Hamilton's principle. The resultant system of ordinary differential equations was solved analytically. The effects of the nanobeam length-to-thickness ratio, thickness, and modes on the buckling and free vibration of the nanobeams were also investigated. Finally, it was found that the buckling and free vibration behavior of a nanobeam is size-dependent and that surface effects and surface energy produce significant effects by increasing the ratio of surface area to bulk at nano-scale. The results indicated that surface effects influence the buckling and free vibration performance of nanobeams and that increasing the length-to-thickness increases the buckling and free vibration in various higher-order shear deformation beam theories. This study can assist in measuring the mechanical properties of nanobeams accurately and designing nanobeam-based devices and systems.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.3
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• pp.35-43
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• 2017

This study was conducted to evaluate effects of Kimchi factory waste (KFW) as bulking agent on physicochemical properties of cow manure (CM) composting and of its application on lettuce growth. Treatments were designed as follows; CM compost [65 % CM + 35 % sawdust (SD); control], KFW 5 % (65 % CM + 30 % SD + 5 % KFW), KFW 10 % (65 % CM + 25 % SD + 10 % KFW) and KFW 15 % (65 % CM + 20 % SD + 15 % KFW). After composting for 25 days, temperature of KFW treatments was lower than that of control. As compared with control, water content of KFW 15 % treatment was low about $5^{\circ}C$, and content of organic matter (O.M.) and nitrogen (N) was higher. pH and O.M./N ratio of KFW treatments or control were unaffected. In comparison with germination index (G.I.), G.I.s of KFW treatments were more than 70 on 25 days and G.I. of control on 35 days. As applied with KFW composts in lettuce, dry weight of KFW 10 % and KFW 15 % were increased by 84 % and 67 %, respectively, than that of control. These results indicated that Kimchi factory waste was possible to use as the compost law materials in livestock manure composting and to replace some sawdust as bulking agent.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.3
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• pp.192-199
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• 1991

To manufacture a good organic fertilizer through rapid composting process, cow dung was mixed with bulking materials such as rice straws, shredded bark, wood chips, and saw dust. The mixing ratio of the cow dung and bulking material was two to one on volume basis and moisture content was adjusted to 60 to 70 percent, C/N ratio 25 to 30 and aeration forced with suction during the aerated pile fermentation. Aerated pile was established outdoors and curing pile was in vinylhouse and the experiment was conducted for 3 years from '88 to '90. After pilling, temperature in aerated pile was reached to the maximum level at 7 to 9 days and the temperatures of cow dung + shredded bark, cow dung + wood chips, and cow dung + rice straws were higher than that of cow dung, and cow dung + saw dust. Total carbon, and C/N ratio in aerated pile fermentation period were increased in the middle stage and then they were decreased with the process of days, and nutrient contents in curing pile period had the same tendency as in the aerated pile.

• Journal of the Korean Wood Science and Technology
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• v.2 no.3
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• pp.3-16
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• 1974

One of the disadvantages of. wood and wood products is their hydroscopicity or dimensional instability. This is responsible for the loss of green volume of lumber as seasoning degrade. Dimensional stabilization is needed to substantially reduce seasoning defects and degrades and for increasing the serviceability of wood products. Recently, considerable world-wide attention has been drawn to the so-called Wood-Plastic Composites by irradiation-and heat-catalyst-polymerization methods and many research and developmental works have been reported. Wood-Plastic Composites are the new products having the superior mechanical and physical properties and the combinated characteristics of wood and plastic. The purpose of this experiment was to obtain the basic data for the improvement of wooden materials by manufacturing WPC. The species examined were Mulpurae-Namoo (Fraxinus, rhynchophylla), Sea-Namoo (Carpinus laxiflora), Cheungcheung-Namoo (Cornus controversa), Gorosae-Namoo (Acermono), Karae-Namoo(Juglans mandshurica) and Sanbud-Namoo (Prunus sargentii), used as blocks of type A ($3{\times}3{\times}40cm$) and type B ($5{\times}5{\times}60cm$), and were conditioned to about 10~11% moisture content before impregnation in materials humidity control room. Methyl methacrylate (MMA) as monomer and benzoyl peroxide (BPO) as initiator are used. The monomer containing BPO was impregnated into wood pieces in the vacuum system. After impregnation, the treated samples were polymerized with heat-catalyst methods. The immersed weights of monomer in woods are directly proportionated to the impregnation times. Monomer impregnation properties of Cheungcheung-Namoo, Mulpurae-Namoo and Seo-Namoo are relatively good, but in Karae-Namoo, it is very difficult to impregnate the monomer MMA. Fig. 3 shows the linear relation between polymer retentions in wood and polymerization times; that is, the polymer loadings are increasing with polymerization times. Furthermore species, moisture content, specific gravity and anatomical or conductible structure of wood, bulking solvents and monomers etc have effects on both of impregnation of monomer and polymer retention. Physical properties of treated materials are shown in table 3. Increasing rates of specific gravity are ranged 3 to 24% and volume swelling 3 to 10%. ASE is 20 to 46%, AE 14 to 50% and RWA 18 to 40%. Especially, the ASE in relation to absorption of liquid water increases approximately with increase of polymer content, although the bulking effect of the polymerization of monomer may also be influential. WPCs from Mulpurae-Namoo and Cheungcheung-Namoo have high dimensional stability, while its of Karae-Namoo and Seo-Namoo are-very low. Table 4 shows the mechanical properties of WPCs from 6 species. With its specific gravity and polymer loading increase, all mechanical properties are on the increase. Increasing rate of bending strength is 10 to 40%, compression strength 25 to 70%, ;impact bending absorbed energy 4 to 74% and tensile strength 18 to 56%. Mulpurae-Namoo and Cheungcheung-Namoo with high polymer content have considerable high increasing rate of strengths. But incase of Karae-Namoo with inferior monomer impregnation it is very low. Polymer retention in cell wall is 0.32 to 0.70%. Most of the polymer is accumulated in cell lumen. Effective. of polymer retention is 58.59% for Mulpurae-Namoo, 26.27% for Seo-Namoo, 47.98% for Cheungcheung-Namoo, 25.64% for Korosae-Namoo, 9.96% for Karae-Namoo and 25.84% for Sanbud-Namoo.

• Journal of the Korea Organic Resources Recycling Association
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• v.5 no.2
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• pp.7-16
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• 1997

The food waste composting facility of 10 ton/d capacity at Nanjido has been operated successfully since July, 1996. This study was performed to investigate the characteristics of food waste quality, and variation of physicochemical characteristics of feed materials during composting. Food waste with 79% moisture content was used as a substrate. Wood chip was used as a bulking agent. Monitoring results based on VS, TOC, C/N ratio and gas composition indicated that the facility was operated normally under aerobic conditions. Conductivity values during food waste composting were increased. A highly positive correlation (r=1.00) existed between VS and TOC.