• Resources Recycling
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• v.5 no.3
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• pp.44-49
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• 1996

One of the most serious problems in utilizing the fly-ash produced from damcstic coal-firing power plants is lhc unburned-carbon mntained m the fly-ash In this shldy, the effects of fruther and collector an the yield,recuvery,unburnedcarbon rejectiou peiccntage,and process efficiency of product (cleaned fly-ash) wcrc examined when convzntional froth flotation was applied to rejcct the unburned-carbon included in the fly-ash of bituminous coal Alsa,the ash analysis for both thc raw and the clcaned fly-ash was conducted to review the change in thc major elements of fly-ash. Experimental results shawcd lhat tlle rcjectlon oI the unburned-cubon of thc raw fly-ash sample is available upto 92.4% using fiath flotalian and that the putity ol the pmdud(c1eancd fly-ash) attains up to 99.4%.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.10
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• pp.645-653
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• 2008

Spiral-jacketed thermal storage tanks can greatly simplify solar heating systems while maintaining the thermal performance at a similar level as conventional systems with an external heat exchanger. Proper design of the spiral-jacket flow path is essential to make the most of solar energy, and thus to maximize the thermal performance. In the present work, computational fluid dynamics (CFD) analysis was carried out for a spiral-jacketed storage tank installed in a solar heating demonstration system. The results of the CFD analysis showed a good agreement with experimentally determined thermal performance indices such as the acquired heat, collector efficiency, and mixed temperature in the storage tank. This verified CFD modelling approach can be a useful design tool in optimizing the shape of spiral-jacket flow path and the flow rate of circulating fluid for better performance.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.15 no.1
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• pp.87-96
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• 1986

An experiment on the devices that enchance the stratification of storage tanks in a solar heat ins system has been carried out. The benefits of thermal stratification in sensible heat storage are to increase the system performance such as the collector efficiency or the fraction of the total load supplied by solar energy. Using the diffuser and the distributor as the stratification enchancement device, the expeliments were perfomed in the different condition of diameter and material of the distributor. As a result of experiments, there exists the diameter of distributor in which the stratification is made maximum under certain design and operation condition. Also it was identified that the kind of distributor material influenced the degree of stratification. Comparing the experimental result to the computational results calculated under the same conditions, the node number N(stratification index) was determined. The results of computer simulation that was performed about the actual solar heating system in Seoul for 24 hours show the relative advantage of stratified over well-mixed storage and the significant improvements in system performance.

• Journal of Electrochemical Science and Technology
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• v.14 no.4
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• pp.369-376
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• 2023

The quick-charging performance of SiO electrodes is evaluated with a focus on solid electrolyte interphase (SEI)-reinforcing effects. The study reveals that the incorporation of fluoroethylene carbonate (FEC) into the SiO electrode significantly reduced the electrode fatigue, which is from the the viscoelastic properties of the FEC-derived SEI film. The impact of FEC is attributed to its ability to minimize the mechanical failure of the electrode caused by additional electrolyte decomposition. This beneficial outcome arises from volumetric stain-tolerant characteristics of the FEC-derived SEI film, which limited exposure of the bare SiO surface during 0.5 C-rate cycling. Notably, FEC greatly improves Li deposition during quick-charge cycles following aging at 0.5 C-rate cycling due to its ability to maintain a strong electrical connection between active materials and the current collector, even after extended cycling. Given these findings, we assert that mitigating SEI layer deterioration, which compromises the electrode structure, is vital. Hence, enhancing the interfacial attributes of the SiO electrode becomes crucial for maintaining kinetic efficiency of battery system.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.5
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• pp.531-540
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• 2008

The main advantage of dissolved air flotation (DAF) in water treatment process is the small dimension compared with conventional gravity sedimentation and it can be basically reduced by the separation zone performed with the short solid-liquid separation time. Fine bubbles make such a short time possible to carry out solid from liquid separation as a collector on the course of water treatment. Therefore, the dimension of separation zone in DAF process is practically determined by the rise velocity of the bubble-floc agglomerates, which is a floc attached with several bubbles. To improve flotation velocity and particle removal efficiency in DAF process, many researchers have tried to attach bubbles as much as possible to flocs. Therefore, the maximum number of attached bubble on a floc and the rise velocity of bubble-floc agglomerates considered as the most important factor to design the separation zone of flotation tank in DAF process was simulated based on the population balance theory. According to the simulation results of this study, the size and volume concentration of bubble influenced on the possible number of attached bubble on a floc. The agglomerates attached with smaller bubble was more sensitive to hydraulic loading rate in the separation zone of DAF process. For the design of a high rate DAF process applied over surface loading 40 m/hr. it is required a precise further study on the variation of bubble property and behavior including in terms of bubble size distribution.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.157.1-157.1
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• 2016

In this work, we experimentally investigated the solar absorption performance of Cu-based scalable nanostructured surfaces and compared their performance with the conventional TiNOX. We fabricated Cu-based nanostructured surfaces with a controlled chemical oxidation process applicable to a large area or complex geometry. We optimized the process parameters including the chemical compounds, dipping time and process temperature. We conducted both lab-scale and outdoor experiments to characterize the conversion efficiency of each absorber surfaces with single and double glazing setup. Lab-scale experiment was conducted with $50mm{\times}50mm$ absorber sample with 1-sun condition (1kW/m2) using a solar simulator (PEC-L01) with measuring the temperature at the absorber plate, cover glass, air gap and ambient. From the lab-scale experiment, we obtained ${\sim}91^{\circ}C$ and $94^{\circ}C$ for CuO and TiNOX surfaces after 1 hr of solar illumination at single glazing, respectively. To measure the absorber performance at actual operating condition, outdoor experiment was also conducted using $110mm{\times}110mm$ absorber sample. We measured the solar flux with thermopile detector (919P-040-50). From outdoor experiment, we observed ${\sim}123^{\circ}C$ and $131^{\circ}C$ for CuO and TiNOX with 0.6 kW/m2 insolation at double glazing, respectively. We showed that the suggested nanostructured CuO solar absorber has near-equivalent collection efficiency compared with the state-of-the-art TiNOX surfaces even with much simpler manufacturing process that does not require an expensive equipment.

• Journal of the Korean Solar Energy Society
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• v.36 no.2
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• pp.41-51
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• 2016

A solar air heater was designed for supplementary domestic heating. The absorber plate had a series of protruding notches which had triangular openings on the front surface of the absorber plate to direct partial air flow to the rear surface and to enhance the convective heat transfer to the flowing air. The height of the opening as well as the opening configuration was determined by preceding numerical simulations. The experimental model had an absorber plate of 0.78-m width and 1.0-m length which was coated with black paint. The air temperature increased as much as $18^{\circ}C$ for $90-m^3/h$ flow rate when the absorber plate was inclined by $45^{\circ}$ for a clear-day solar irradiation of about $906W/m^2$. The collector efficiency ranged from 69 to 74%. Considering the simplicity of the structure and low manufacturing cost, the solar air heater might have competence as an auxiliary heating device for domestic use. On-site experimental results are presented with discussion for various solar irradiations and air flow conditions.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.57.2-57.2
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• 2011

Dye-sensitized solar cells (DSSC) have recently been developed as a cost-effective photovoltaic system due to their low-cost materials and facile processing. The production of DSSC involves chemical and thermal processes but no vacuum is involved. Therefore, DSSC can be fabricated without using expensive equipment. The use of dyes and nanocrystalline $TiO_2$ is one of the most promising approaches to realize both high performance and low cost. The efficiency of the DSSC changes consequently in the particle size, morphology, crystallization and surface state of the $TiO_2$. Nanocrystalline $TiO_2$ materials have been widely used as a photo catalyst and an electron collector in DSSC. Front electrode in DSSC are required to have an extremely high porosity and surface area such that the dyes can be sufficiently adsorbed and be electronically interconnected, resulting in the efficient generation of photocurrent within cells. In this study, DSSC were fabricated by an screen printing for the $TiO_2$ thin film. $TiO_2$ nanoparticles characterized by X-ray diffractometer (XRD) and scanning electron microscope (SEM) and scanning auger microscopy (SAM) and zeta potential and electrochemical impedance spectroscopy(EIS).In addition, DSSC module was modeled and simulated using the SILVACO TCAD software program. Improve the efficiency of DSSC, the effect of $TiO_2$ thin film thickness and $TiO_2$ nanoparticle size was investigated by SILVACO TCAD software program.

• Korean Journal of Veterinary Service
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• v.31 no.2
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• pp.229-237
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• 2008

This study was conducted to evaluate the effect of honeybee venom, purified using bee venom collector, and feeding of probiotics on the body weight gain, growth rate and hematological characteristics of pigs. A total of 120 pigs were examined and divided into 4 groups 1) Control (basal diet), 2) BV (basal diet + bee venom), 3) PB (basal diet + probiotics), 4) BVPB (basal diet + BV + PB). Average daily weight gain improved significantly in all test groups, especially BVPB (P < 0.05) compared to the controls. There was a significant difference in the feed conversion rate (P < 0.05) and efficiency (P < 0.05) between BVPB and control pigs. Weight gain and survivability was higher in the tests than the controls, but white blood cell count was not. Serum total protein, albumin and IgG concentration of BVPB were slightly higher than those of controls. These results suggest that treated honeybee venom and probiotics should be used together to effectively increase the productivity of pigs.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.481-484
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• 2008

Recently, the recycling and reusing of construction and demolition waste concrete is urgently required because waste concrete is greatly increased according to the rapid increasing of urban redevelopment project, but the problem solution for demand and supply unbalance of fine aggregate is urgently required because of the restriction of collecting sea fine aggregate. So the utilization of high quality recycled fine aggregate using construction and demolition waste concrete as new fine aggregate for construction industry is urgently. Accordingly, In this study, As recycled fine aggregate manufacturing technology with exceeding in economical efficiency, reduction efficiency of environmental load and quality improvement effect of recycled fine aggregate, it is to develop dry manufacturing system composed specific gravity separator of high-speed rotation impact type and centrifugal Force Powder Collector, etc. And it is to examine mechanism of recycled sand dry manufacturing system.