• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.5 no.4
• /
• pp.1-9
• /
• 2002

This study is carried out to make the environmentally affinitive porous planting block for revegetation and to make a effective program for greening plans. The summary is shown below. 1. In order to get stronger intensity and distribute proper porosity in the block for planting, the cements mixed with fine soil were used and the finer in soil grains gives the stronger in intensity of the cements. Use of the furnace slag cements instead of the portland cements showed relatively stronger in intensity of the block. The intensity of the block became stronger when the mixed ratio of the cements to soil is 5 : 1, but the pore space ratio was lower. The percolate pH of the portland cements after one month of treatment was 13.1 but the percolate pH of the furnace slag cements was shown lower. To mold proper porous planting blocks, the proper combination of additives such as the dehydrating agent, elastic agent and adhesives into the mixture of cements and soil gives better effectives. 2. After molding the porous planting blocks, it gave a better result when the grains of the filler made of peat moss, upland soil and compound fertilizer were smaller than 2 mm in size. Shaking of the filling materials also gave the better result, but it took more time and cost much more. Therefore, it was better when the filling materials were mixed with water first then flew down for stuffing. 3. It was necessary to cover with soil after seeding or planting on the porous planting blocks. The proper thickness of the soil to help root development and keep moisture is about 3~5 cm. 4. The plants for planting on the porous planting block were required stronger in the growth condition of their roots and their environmental adaptability. The average germination percentage and rate of Platycodon grandiflorum on the porous planting block were 88.8% and 85% accordingly and their rate is very uniform. The germination rates of Dianthus superbus var. longicalycinus and Taraxacum officinale were more than 50%. These grass species, Chelidonium majus var. asiaticum, Lysimachia mauritiana and Scabiosa mansenensis were the suggested biennial grasses in the planting area where exchanging of the seedling or nursery plants was not necessary because their germination rates were 59.3, 45.6 and 40.3% accordingly. Viola kapsanensis, Chrysanthemum sp., Taraxacum sp. and Iris ensata var. spontanea are the grass species that could be used by seeding for greening. However, the germination rate of Solidago virga-aurea var. asiatica, Aster scaber and Lythrum anceps were lower than 10%. The coverage ratio of Ixeris stolonifera is more than 80% after 60 days seeding and the root length of most of species are more than 10 cm except Iris ensata var. spontanea and Platycodon grandiflorum because their root developed thicker than other species.

• Resources Recycling
• /
• v.5 no.3
• /
• pp.65-72
• /
• 1996

Colloidal calcium wrbonate(diametcr 0.02-0 09 m~wja s developed to maintain the mamenl of pnriide formatio~>w ~lhoutsurlace trealment. The control factors of particle size and optimum condiliuna for compound fam*tition has not bccn studiedyet. This shldy war aimed at developing a method fur compounding colloidal calcium carbonfcte to cnl~hol cubic calciumcarbonate, and then compounding the b-o types oI precipitated calcium wrbonatc under optimum wndilrans Calc~umhydroxide was calcinated at 1, lWC far two hours, md then hydrated for 30 minutes at t i i O rprn and ambiznt temperahlle.Two-liter suspension was subjected to the contact with carbon dioxide at l5"C, 600 ipxn and C0= injection in the rate of 1 Umin Two types of dcium carbonate(cuhic calcium carbonatc(0 24.9 pm) md collnidd calcium mhnnate (0.02-0 09 pm))were compounded by "wing the concentrations of calcium oxide and ihe suspension were compounded. It was found that theoptimum concentrations of each suspensions were 5 wt % and 2.5 \I*.% respectively. ' h c key control factor af thc parlicle slzcdislribution was the concenkation al the suspension. The size of compounded particles was measured by a Zcla S k r 'fieaverage particle size of the cubic calcium carbonate aas 223.4 nm(0.223 pm), and that of thc colloidal a~lciumc arbonate was93.6 nm (0.093 km). Ihe particle sizc was evenly cantlolled on a stdblc basis in an H, O reaction system.asis in an H, O reaction system.

• Resources Recycling
• /
• v.5 no.3
• /
• pp.56-64
• /
• 1996

C,H,OH system is widely used for producing synthetic beverages and pharmaceuticals. Calcium hydroxide suspension was used to callhol the morphology of calcium carbonate, and the charactenstics of the formahan and crystsllizatian of calcium cilrbonate by adding ethylenc glycol were determined A reaclor was made with attaching a ceramic bubble plate, and lhe eleclrical conductivity was continously monitored during the rcaction with CO, gas. A part of the suspension was separated and powdered at the transition point. XRD and electron microscopic observation showed that the intermedmte and final products were vilterite, ;~r;lganite and calcite. In this study, the volumc of the ethylene glycol added to CH,OH was fixed a1 10 vol\ulcornerh. The valumc of the suspension was 500 ml, and the changes oi characteristics were shdied along with variims cnntents(l0-50 g) of calcium hydroxide. Except m the case of 10 g of calcium hydroxide at the crystallization stagc, all of products showed gelation. Tne marc the calcium hydroxide the shorter the formation time. Alsa. the farmalion of spherical valcrile ivas obsemcd when 30 g Ca(OH), was added. Tne vaterite(a compound material) can bc synthesised under alnbienl pressure and lempcmhre m a C,H,OH system by morphology control. Even though the vateritc was meta-stable phasc and could bc changed to calcitc easily, the stable and spherical vateritc was observed by using G5 glass fillers and vacuum dricrs.

• Korean Journal of Food Science and Technology
• /
• v.34 no.3
• /
• pp.480-486
• /
• 2002

Six strains of intestinal pathogenic bacteria were inoculated into kimchi at the preparation time, and the influence of kimchi fermentation on the growth of these pathogenic bacteria was investigated. The population of coliform bacteria in the kimchi raw materials, and its changes in the kimchi sample during fermentation were also determined. Among the raw materials, highest populations of coliform bacteria were detected in ginger and green onion, followed by Chinese cabbage, red pepper, and garlic. Populations of pathogenic bacteria (inoculated strains) and coliform bacteria in kimchi decreased as pH decreased with fermentation. Coliform bacteria disappeared at pH 3.9 in Chinese cabbage kimchi samples. Clostridium perfringens ATCC 13124, Listeria monocytogenes ATCC 19111, Salmonella typhimurium KCTC 1625, Staphylococcus aureus KCTC 1621, Vibrio parahamolyticus ATCC 27519, and Escherichia coli O157 H:7 ATCC 43894 were not detected at pH values less than 4.1, 3.7, 3.8, 3.8, 3.7, and 3.7 in Chinese cabbage kimchi, and at pH values less than 4.5, 4.0, 4.2, 4.2, 4.2 and 4.1 in mustard leaf kimchi, respectively. The juice of mustard leaf and allyl isothiocyanate exhibited high antimicrobial activities on the pathogenic bacteria, whereas the lowest on lactic acid bacteria. These results indicated that fermentation is useful to improve the safety of kimchi, and the antimicrobial effect of mustard leaf kimchi is mainly due to the major pungent compound of mustard leaf, allyl isothiocyanate.

• Korean journal of applied entomology
• /
• v.60 no.3
• /
• pp.315-322
• /
• 2021

This study investigated the acaricidal and repellent activities of various plant extracts and Cnidium officinale-derived materials against Haemaphysalis longicornis. Among the 24 methanolic plant extracts, C. officinale showed the highest acaricidal activity (93.3%) against H. longicornis. Platycodon grandiflorus, Phytolacca americana, Magnolia denudata, Houttuynia cordata, C. officinale, and Pueraria montana showed significant differences in their repellent activity. Consequently, the activity of solvent-fractionated materials and the derived material of the C. officinale, was investigated and a 90% acaricidal effect was observed three days after hexane fraction treatment, indicating that the repellent response was statistically significant. Butylidenephthalide, which is a C. officinale-derived compound, showed 90% acaricidal activity seven days after treatment. Additionally, all H. longicornis moved to the untreated area in the t-tube olfactometer experiment, confirming the repellent activity of butylidenephthalide. Therefore, the results of this study suggest the use of C. officinale crude extract and butylidenephthalide as potent acaricidals and repellents against H. longicornis, respectively.

• Journal of Life Science
• /
• v.29 no.1
• /
• pp.90-96
• /
• 2019

The objective of this study was to evaluate the potential of Diospyros malabarica stem extract, a natural materials, in oral health material. With this aim in mind, thin layer chromatography (TLC), TLC-bioautography, high-performance liquid chromatography (HPLC), electrospray ionization-mass spectrometry (ESI-MS), scanning electron microscopy (SEM), and real-time qPCR were performed. The antibacterial activity of D. malabarica stem extract against Streptococcus mutans KCTC3065 was confirmed in an n-hexane fraction with low polarity. The molecular weight of the antibacterial compound was estimated to be 188 by ESI-MS analysis. The inhibitory effects of the extract on biofilm formation and gene expression related to biofilm formation of S. mutans were determined by SEM and real-time PCR analysis. The extract inhibited the formation of S. mutans biofilms at D. malabarica stem extract concentrations of 1 mg/ml, as shown by SEM. The real-time PCR analysis showed that the expression of the gtfC gene, which is associated with biofilm formation, was significantly decreased in a dose-dependent manner. Based on the above results, it can be concluded that D. malabarica stem extracts, a natural materials, can be used in oral health products to suppress the formation of biofilms by inhibiting tooth adhesion of S. mutans, a causative agent of dental caries.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.36 no.5
• /
• pp.454-462
• /
• 2023

Flash lamp annealing (FLA) of metal nanoparticle (NP) ink has provided powerful strategies to fabricate high-performance electrodes on a flexible substrate because of its rapid processing capability (in milliseconds), low-temperature process, and compatibility with to roll-to-roll process. However, metal NPs [e.g., gold (Au), silver (Ag), copper (Cu), etc.] have limitations such as difficulty in synthesizing fine metal NPs (diameter less than 10 nm), high price, and degradation during ink storage and FLA processing. In this regard, organometallic ink has been proposed as a material that can replace metal NPs due to their low-cost (usually 1/100 times cheaper than metal nano inks), low-temperature processability, and high material stability. Despite these advantages, the fabrication of flexible electrodes through FLA treatment of organometallic compounds has not been extensively researched. In this paper, we experimentally guide how to determine the optimal conditions for forming electrodes on flexible substrates by considering material parameters, and flashlight processing parameters (energy density, pulse duration, etc) to minimize the difficulties that may arise during the FLA of organometallic ink.

• Journal of the Society of Disaster Information
• /
• v.19 no.3
• /
• pp.532-544
• /
• 2023

Purpose: To identify and evaluate the risk of chemical fire causative substances by using thermal analysis methods (DSC, TGA) for the hazards and physical property changes that occur when newly used biofuels are mixed with existing fuels It is to use it for identification and evaluation of the cause of fire by securing data related to the method and the hazards of the material according to it. Method: The research method used in this experiment is the differential scanning calorimeter (DSC: Difference in heat flux) through quantitative information on the caloric change from the location, shape, number, and area of peaks. flux) was measured, and the weight change caused by decomposition heat at a specific temperature was continuously measured by performing thermogravimetric analyzer (TGA: Thermo- gravimetric Analyzer). Result: First, in the heat flux graph, the boiling point of the material and the intrinsic characteristic value of the material or the energy required for decomposition can be checked. Second, as the content of biodiesel increased, many peaks were identified. Third, it was confirmed through analysis that substances with low expected boiling points were contained. Conclusion: It was shown that the physical risk of the material can be evaluated by using the risk of biodiesel, which is currently used as a new energy source, through various physical and chemical analysis techniques (DSC + TGA).In addition, it is expected that the comparison of differences between test methods and the accumulation and utilization of know-how on experiments in this study will be helpful in future studies on physical properties of hazardous materials and risk assessment of materials.

• Korean Journal of Materials Research
• /
• v.34 no.4
• /
• pp.208-214
• /
• 2024

To fabricate intermetallic nanoparticles with high oxygen reduction reaction activity, a high-temperature heat treatment of 700 to 1,000 ℃ is required. This heat treatment provides energy sufficient to induce an atomic rearrangement inside the alloy nanoparticles, increasing the mobility of particles, making them structurally unstable and causing a sintering phenomenon where they agglomerate together naturally. These problems cannot be avoided using a typical heat treatment process that only controls the gas atmosphere and temperature. In this study, as a strategy to overcome the limitations of the existing heat treatment process for the fabrication of intermetallic nanoparticles, we propose an interesting approach, to design a catalyst material structure for heat treatment rather than the process itself. In particular, we introduce a technology that first creates an intermetallic compound structure through a primary high-temperature heat treatment using random alloy particles coated with a carbon shell, and then establishes catalytic active sites by etching the carbon shell using a secondary heat treatment process. By using a carbon shell as a template, nanoparticles with an intermetallic structure can be kept very small while effectively controlling the catalytically active area, thereby creating an optimal alloy catalyst structure for fuel cells.

• Resources Recycling
• /
• v.33 no.3
• /
• pp.21-29
• /
• 2024

Globally, the demand for electric vehicles (EVs) is surging due to carbon-neutral strategies aimed at decarbonization. Consequently, the demand for lithium-ion batteries, which are essential components of EVs, is also rising, leading to an increase in the generation of spent batteries. This has prompted research into the recycling of spent batteries to recover valuable metals. In this study, we aimed to selectively leach and recover lithium from the cathode material of spent LFP batteries. To enhance the reaction surface area and reactivity, the binder in the cathode material powder was removed, and the material was subjected to heat treatment in both atmospheric and nitrogen environments across various temperature ranges. This was followed by a mechanochemical process for aqueous leaching. Initially, after heat treatment, the powder was converted into a soluble lithium compound using sodium persulfate (Na₂S₂O₈) in a mechanochemical reaction. Subsequently, aqueous leaching was performed using distilled water. This study confirmed the changes in the characteristics of the cathode material powder due to heat treatment. The final heat treatment in a nitrogen atmosphere resulted in a lithium leaching efficiency of approximately 100% across all temperature ranges.