• Resources Recycling
• /
• v.29 no.6
• /
• pp.41-47
• /
• 2020

This study was carried out to utilize the coal bottom ash generated in a circulating fluidized bed combustion boiler as a treatment agent for heavy metal ions, and experiments were conducted to remove heavy metal ions from the acid mine drainage. The batch experiments were conducted to investigate the influence of dosage of ash, initial concentration of solution on the removal capacity of heavy metal ions (Cu, Cd, Cr, Pb). The results of the experiment showed that the total removal capacity of heavy metals was 30.8 mg/L and 46.4 mg/g, respectively, under the condition that the concentration of coal ash was added as 15 g/L of heavy materials and 10 g/L of light materials. After that, a long-term column experiment was performed to determine the maximum removal capacity of heavy metal ions (Cu, Cd, Cr, Pb, As), and the removal capacity for each metal component was investigated. After approximately 60 days of operation, the maximum removal capacity of heavy metals was 23.6 mg/g at pH 9.25.

• The Journal of the Convergence on Culture Technology
• /
• v.10 no.6
• /
• pp.613-618
• /
• 2024

This study aimed to derive the optimal mixing ratio that secures the required performance of the road body(unconfined compressive strength: 0.44 MPa based on 28 days of curing) by applying soil stabilizer utilizing recycled resources and the in-situ soil that cannot be applied to the road body. To this end, the unconfined compressive strength was measured for three mixing ratios of soil stabilizer (80 kg, 100 kg, and 120 kg per 1m³) at 3, 7, 14, and 28 days of curing. As a result of measuring the unconfined compressive strength by curing day and mixing ratio, it was confirmed that the unconfined compressive strength increased as the mixing ratio of soil stabilizer utilizing recycled resources increased. It was confirmed that more than 100 kg of soil stabilizer utilizing recycled resources per 1m³ should be mixed to satisfy the required performance of the road body.

• The Journal of the Convergence on Culture Technology
• /
• v.10 no.6
• /
• pp.591-596
• /
• 2024

In this study, a gel time test in laboratory test and a homogel compressive strength test for each curing day were conducted to compare low cement injection materials utilizing recycled resources as replacement materials for OPC and SC used in the SGR method. In the case of the gel time test, OPC and SC showed results that satisfied the quick setting and final setting conditions presented in the standard mixing ratio. In the case of low cement injection material utilizing recycled resources, the gel time under quick setting conditions was not satisfied. As a result of conducting a gel time test of low cement injection material using recycled resources under quick setting conditions using a modified mixing ratio, the average time was found to be 8.8 sec, confirming that it satisfies the quick setting conditions. In addition, as a result of measuring the homogel compressive strength with a mixing ratio that satisfies the gel time conditions, the compressive strength was found to be 1.12-1.88 MPa as of the 28th day.

• Korean Chemical Engineering Research
• /
• v.44 no.5
• /
• pp.489-497
• /
• 2006

The economical efficiency of conversion of the PC (pulverized coal) firing boiler to the CFB (circulating fluidized bed) boiler which used Koran anthracite as fuel was evaluated. The economic feasibility study was also carried out with regard to maintenance of the existing PC boiler. The sensitivity of economical efficiency with variation of the electric power and coal industry and the policy of government was analyzed and compared. As a results of the evaluation, the economical efficiency of maintenance of the existing PC boiler was higher than that of conversion to the CFB boiler because of the special policy of the government for Korean anthracite. However, the conversion to the CFB boiler was more economically attractive from a point of view of effective use of energy resources and future electric power industry. Additionally, the fund support for electric power industry using Korean anthracite would be effective as changing the policy of the government.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.22 no.4
• /
• pp.60-67
• /
• 2018

As the lack of specific aggregation intensifies, the development of alternative resources is urgent. Construction waste is increasing every year, but recycled aggregate is used as a low value added material. Various studies are currently underway at the national level. In this paper, the mechanical performance of the concrete according to the concrete mixing method and the replacement amount of the circulating coarse aggregate was compared and evaluated. Concrete mixing method was normal mixing approach(NMA) method, two-stage mixing approach1 (TSMA1) method, two-stage mixing approach2 (TSMA2) method. Fresh concrete was tested for air content, slump test, and unit volume weight. Compressive strength and flexural strength were tested in hardened concrete. According to the TSMA method, the mechanical performance difference of concrete is shown, and the strength is decreased according to the circulating coarse aggregate replacement amount.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.34 no.4 s.117
• /
• pp.105-115
• /
• 2006

Biotope Area Ratio ($BFF; BiotopFl{\"{a}}chenFaktor$) was developed in Berlin, Germany in 1990s and introduced to Korea in 1999. It is the ratio of the uncovered soil areas which have the natural circulating capability compared to whole development areas. This study seeks for alternative ways to increase Biotope Area Ratio of residential areas in the metropolitan areas of Korea by investigation on new housing developments. The study investigates four new towns including Seoul Eunpyung new town, Yongin Kusung district, Goyang Pungdong and Juyeopdong districts and Hwasung Dongtan district. The Biotope Area Ratio of study sites is between 23.51 % and 40.69%. This result is not relevant to land use conditions, such as the building-ta-land ratio, natural ground green area ratio. This ratio satisfies the minimum requirements of City of Seoul, except 2 sites. Considering that the study sites are relatively low density land use areas compared to Seoul's average, thus, a higher standards is necessary for new town housing complexes. Because Biotope Area Ratio includes artificial ground green area ratio, Biotope Area Ratio is possible can be increased with decreased natural ground green area ratio. And so, when Biotope Area Ratio is applied to new town development, it must go side by side with a definite natural ground green area ratio.

• Journal of Korean Society on Water Environment
• /
• v.22 no.1
• /
• pp.159-165
• /
• 2006

Numerical simulation of turbulence flow in a circulating channel was performed. The RNG $k-\varepsilon$ model and Reynolds stress model of the FLUENT was used for evaluating the flow mechanisms. The simulation results were compared with the experimental data measured by a ADV (Acoustic Doppler Velocitmeter). The distribution of chironomids was analyzed by the computational results. They distributed at the region of lower velocities and lower turbulence intensity. In the case of a hemisphere structure being located on the straight section, chironomids lived in the upstream and downstream area of the hemisphere. The secondary currents also affected the distribution of chironomids. In conclusion, the computational fluid dynamic techniques can be inexpensively applied for analysing the relationship between flow characteristics and distribution of benthic macroinvertebrates.

• Journal of Aquaculture
• /
• v.8 no.1
• /
• pp.21-29
• /
• 1995

Triploid cherry salmon (Oncorhynchus masou) were induced by the heat shocking treatment of fertilized eggs 10 minutes post fertilization at $28^{\circ}C$ for 15 minutes. Haematological and physiological characteristics of diploid and the induced triploid fish were examined just before the spawning period. Triploids had significantly lower concentrations of circulating red blood cells than that of diploids (P<0.01). However, oxygen consumption, hematocrit, hemoglobin, RBC, and mean concentration of hemoglobin within the RBC of triploids were higher than those of diploids. The concentrations of total protein, albumin and cholesterol from triploids were also higher than those from diploids.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.25 no.5
• /
• pp.369-375
• /
• 2020

Distribution energy resources have been increasing in recent years. However, output power is limited for distribution network stability. This study proposes an active distribution network that can reconfigure distribution lines by using an active phase controller. A conventional distribution network has a fixed structure, whereas an active distribution network has a variable structure. Therefore, the latter can increase the output power of distribution energy resources and decrease the overload of distribution line facilities. An active phase controller has two operation modes for minimizing circulating current during dynamic reconfiguration. In this study, voltage and current control algorithms are proposed for active phase controllers. The simulation of the proposed methods for active phase controllers is performed using PSIM software.

• Journal of Distribution Science
• /
• v.21 no.9
• /
• pp.81-91
• /
• 2023

Purpose: The article aims to assess the possibilities and contribution of countries to the creation and distribution of knowledge circulating in the scientific and technological space of the EAEU. Research design, data, and methodology: To understand the conditions and possibilities for the distribution of knowledge, the methodology of the quality of economic space used. The space is considered through density, placement, connectedness, and asymmetry. Used bibliometric analysis, balance of payments analysis, and integration indicators. Results: The study showed that low barriers, including language, created visible advantages in the mutual distribution of knowledge. However, the geo-technological space of the EAEU is polarised and has differences in the density and distribution of scientific resources. Asymmetries are shown in the distance between countries in multidirectional trends. Cooperation between countries has a different level of interaction. Conclusions: The internal resources of the geo-technological space of the EAEU are limited, and most of the needs are covered by external sources. Some mechanisms of the scientific policy of countries in scientific careers act as «demotivates» for distributing knowledge within the EAEU. Countries need to improve the quality of services and trade data to better understand technology distribution processes through bilateral channels.