• Journal of the Korean Recycled Construction Resources Institute
• /
• v.8 no.4
• /
• pp.387-394
• /
• 2020

In this research, a physical property test of CLSM, which can safely and effectively utilize a great number of industrial byproducts and waste types, was used to review the applicability of GBFS, FNS, and FGB, as well as their field applicabilities as cavity fillers, and the following conclusions have been reached. first, For CLSM utilizing GBFS, FNS, and FGB, it was revealed that a proper mixing of over 30% of GBFS and FNS or within 5% of FGB is effective in improving the fluidity for field application. second, It was revealed that GF15B5 can suppress bleeding at a similar level as the base, whereas GF30B5 can do so at about 0.17% compared to the base. It was also verified that GF15, GF30, and GF45 can suppress bleeding at about 0.2%, 0.26%, and 0.3%, respectively, compared to the base. third, Both GF15B5 and GF30B5 exceeded 0.4MPa in 7day strength tests to satisfy the field application and, also, the rates of increase of their initial strengths were found to be 323% and 233% higher than the base, respectively. Meanwhile, the 7day strength test of GF, which utilizes GBFS and FNS, also reached over 0.2MPa for field application, and it was revealed that GF15, GF30, and GF45 show 160%, 237%, and 185% higher strength increase rates, respectively, compared to the base.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.10 no.1
• /
• pp.23-29
• /
• 2022

This study was conducted to confirm the applicability of recycled aggregates as aggregates for structural concrete as a way to respond to the shortage of natural aggregates. The two-stage mixing approach developed by Tam et al. is known to be a method that can improve the mechanical performance of recycled aggregate concrete without the installation of new additional facilities. In this work, modified version of two stage mixing approach, which was used in our earlier work, was introduced to prepare mortar specimens with recycled fine aggregate, and the compressive strength and fire resistance were compared to mortar mixed with normal mixing approach. According to the experimental results from mortar with recycled fine aggregate, the use of two-stage mixing approach was found to be more effective than normal mixing approach for compressive strength development. In addition, the residual strengths of the mortar with two-stage mixing approach was higher than mortar made of normal mixing approach after exposure to 600 and 900 ℃. It is possible to manufacture high-performance cement composites with recycled fine aggregates through the active use of the two-stage mixing approach.

• Korean Chemical Engineering Research
• /
• v.61 no.3
• /
• pp.407-411
• /
• 2023

The urease is covalently immobilized on the surface of the magnetic particles to catalyze the conversion of urea to bicarbonate anion. The conversion was confirmed qualitatively using high-pressure liquid chromatography and UV/Vis spectrometry, and analyzed quantitatively with cyclic voltammetry. The amount of conversion with respect to time was measured and analyzed by the reaction rate equation to calculate a reaction rate constant of 0.0474 min-1. In the 1 to 3 cycles, a conversion percentage of over 90% was found, and it was possible to reuse the urease 8 times up to the percentage of 50%. It was also observed that the stability evaluated for storage for 30 days was maintained. As a result of this study, it can be seen that the urease covalently immobilized on the scaffold can be used for urea removal for the purpose of producing ultrapure water.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.1 no.1
• /
• pp.11-23
• /
• 2003

A study on the electrolytic dissolution of SUS-304 and Inconel-600 specimen was carried out in neutral salt electrolyte to evaluate the applicability of electrochemical decontamination process for recycle or self disposal with authorization of large amount of metallic wastes contaminated with uranium compounds generated by dismantling a retired uranium conversion plant in Korea. Although the best electrolytic dissolution performance for the specimens was observed in a Na2s04 electrolyte, a NaNO$_3$ neutral salt electrolyte, in which about 30% for SUS-304 and the same for Inconel-600 in the weight loss was shown in comparison with that in a Na$_2$SO$_4$ solution, was selected as an electrolyte for the electrochemical decontamination of metallic wastes with the consideration on the surface of system components contacted with nitric acid and the compatibility with lagoon wastes generated during the facility operation. The effects of current density, electrolytic dissolution time, and concentration of NaNO$_3$ on the electrolytic dissolution of the specimens were investigated. On the basis of the results obtained through the basic inactive experiments, electrochemical decontamination tests using the specimens contaminated with uranium compounds such as UO$_2$, AUC (ammonium uranyl carbonate) and ADU (ammonium diuranate) taken from an uranium conversion facility were performed in 1M NaNO$_3$ solution with the current density or In mA/$\textrm{cm}^2$. it was verified that the electrochemical decontamination of the metallic wastes contaminated uranium compounds was quite successful in a NaNO$_3$ neutral salt electrolyte by reducing $\alpha$ and $\beta$ radioactivities below the level of self disposal within 10 minutes regardless of the type of contaminants and the degree of contamination.

• Journal of Korean Home Economics Education Association
• /
• v.18 no.3 s.41
• /
• pp.1-22
• /
• 2006

The purpose of this study is that I should look for a desirous directions about home economics by studying the requirements and perception of the high school parents who have finished the course of home economics. It was about 600 parents whom I have searched Seoul-Pusan, Ganwon. Ghynggi province, Choongcheong-Gyungsang province, Cheonla and Jeju province of 600, I chose only 560 as apparently suitable research. The questions include 61 requirements about home economics and one which we never fail to keep among the contents, whenever possible and one about the perception of home economics aims 11 about the perception of home economics courses and management. The collections were analyzed frequency, percent, mean. standard deviation t-test by using SAS program. The followings is the summary result of studying of it. 1. All the boys and girls learning together about the Idea of healthy lives and desirous human formulation and knowledge together are higher. 2. Among the teaching purposes of home economics, the item of the scientific principle and knowledge for improvements of home life shows 15.7% below average value. 3. The recognition degree about the quality of home economics is highly related with the real life, and about the system. we recognize lacking in periods and contents of home economics field and about guiding content, accomplishment and application qualities are higher regardless of sex. 4. The important term which we should emphasize in the subject of home economics is family part. 5. Among the needs of home economic requirement in freshman, in the middle unit, their growth and development are higher than anything else, representing 4.11, and by contrast the basic principle and actuality is 3.70, which is lowest among them. 6. In the case of second grade requirement of home economics content for parents in the middle unit young man and consuming life is 4.09 highest. 7. In the case of 3rd grade requirement of economics contents in the middle unit the choice of coming direction and job ethics is highest 4.16, and preparing meals and evaluation is lowest 3.50.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.1
• /
• pp.75-84
• /
• 2005

The aim of this study is to evaluate the leaching characteristics of lead, copper, cadmium, and mercury from steel making slag by seawater. To demonstrate the leaching characteristics of heavy metals from steel making slag by seawater, it was carried to various leaching tests such as regular leaching tests, liquid/sold(LS) leaching test and pH static test. From the leachability of $Pb^{+2},\;Cu^{+2},\;and\;Cd^{+2}$ from steel making slag in pH static test, it is distinguished between distilled water and seawater. With distilled water, it is very low between pH 7-8 and pH 11-12. On the other hands, with the seawater, its leaching is higher than that of distilled water. In particular, concentration of $Hg^{+2}$ leached from slag by seawater is lower than that of distilled water. Meanwhile, we found that the heavy metals from steel making slag would be dissolved and precipitated using geochemcial equilibrium program such as visual minteq. Lead and copper leached from steel making slag with seawater were dissolved nearly in the range of pH 11-12, but in the range of pH 7-10 those were precipitated about 90%. And cadmium leached from steel making slag with seawater were dissolved completely. On pH static test with distilled water, lead leached from steel making slag seemed to be similar to pH static test with seawater. However, copper and cadmium leached from steel making slag were dissolved. In general, the species of lead leached from steel making slag were formed mainly of $PbCl^+,\;PbSO_4$, the species of copper were formed mainly of $CuSO_4,\;CuCO_3$, the species of cadmium were formed mainly of $CdCl^+,\;CdSO_4$ due to being sorbed with the anions($Cl^-,\;CO_3^{-2},\;SO_4^{-2}$) of the seawater. Both pH static test with seawater and distilled water, it is not in the case of the mercury. Most of mercury leached from steel making slag was precipitated(SI=0). Because the decreasing of $Hg^{+2}$ concentrations depends ferociously on the variation of chloride($Cl^-$) existed in the seawater. $Hg^{+2}$ leached from steel making slag could be sorbed strongly with chloride($Cl^-$) compared of carbonate($CO_3^{-2}$) and sulfate($SO_4^{-2}$) in the seawater. On the basis of that result, we found that the species of mercury was formed of calomel($Hg_2Cl_2$) as one of finite solid. Due to forming a calomel($Hg_2Cl_2$) in the seawater, the stability of mercury species by steel making slag should be higher than those of lead, copper, and cadmium species. Regarding the results stated above, we postulated that the steel making slag could be recycled to sea aggregates due to being distinguishing leachability of heavy metals($Pb^{+2},\;Cu^{+2},\;Cd^{+2},\;and\;Hg^{+2}$) between leaching tests by distilled water and seawater.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.28 no.4
• /
• pp.323-330
• /
• 2008

This study was carried out to evaluate the effect of application of cattle manure and chemical fertilizer on dry matter productivity and nutritive values of rye and hairy vetch according to two different sowing methods such as single or mixed-sowed cultivation. Dry matter and TDN yields for rye single culture, and rye and hairy vetch mixed culture were 7.2 and 4.0 ton/ha, and 8.0 and 4.4 ton/ha, respectively. They were significantly (p<0.05) higher than that (4.5 and 2.7 ton/ha) of hairy vetch single culture. Moreover, plots produced by mixed-sowing cultivation had a higher crude protein (CP) as 7.7% than that of only rye plot, and higher TDN and RFV as 55.8 and 79.4%, respectively. Within rye alone plots, completely cattle slurry application produced significantly higher annual DM and TDN yields (7.4 and 4.1 ton/ha) than those of P+K fertilization (7.2 and 3.9 ton/ha) as a chemical fertilizer and non-fertilizer (5.5 and 3.1 ton/ha). Cattle slurry application plot revealed 75.52 and 78.97% of N+P+K fertilization plot for annual DM and TDN, respectively. Within mixed-sowing cultivation with rye and hairy vetch, completely cattle slurry application produced 7.6 ton/ha DM and 4.5 ton/ha TDN, showing 79.50 and 86.77% of N+P+K fertilization plot, respectively. Furthermore, the CP content for cattle slurry plots was 8.5%, which was significantly (p<0.05) higher than those of other plots, and it was also highest in TDN (58.3%) and RFV (86). Overall, rye mixed-sowing with hairy vetch rather than rye alone sowing reduced DM yields, but leaded to enhancement of feed value and nutritive yields. And also, it would be expected that cattle slurry application in comparison with chemical fertilizers might result in reutilization of resources, improved forage quality and, extended harvest period by preventing feed value from rapidly deteriorating.

• Journal of Radiation Protection and Research
• /
• v.40 no.2
• /
• pp.79-86
• /
• 2015

$^3He$ gas has been used for neutron monitors as the neutron converter owing to its advantages such as high sensitivity, good ${\gamma}$-discrimination capability, and long-term stability. However, $^3He$ is becoming more difficult to obtain in last few years due to a global shortage of $^3He$ gas. Accordingly, the cost of a neutron monitor using $^3He$ gas as a neutron converter is becoming more expensive. Demand on a neutron monitor using an alternative neutron conversion material is widely increased. $^{10}B$ has many advantages among various $^3He$ alternative materials, as a neutron converter. In order to develop a neutron converter using $^{10}B$ (actually $B_4C$), we calculated the optimal thickness of a neutron converter with a Monte Carlo simulation using MCNP6. In addition, a neutron converter was fabricated by the Ar sputtering method and the neutron signal detection efficiencies were measured with respect to various thicknesses of fabricated a neutron converter. Also, we developed a 2-dimensional multi-wire proportional chamber (MWPC) for neutron beam profile monitoring using the fabricated a neutron converter, and performed experiments for neutron response of the neutron monitor at the 30 MW research reactor HANARO at the Korea Atomic Energy Research Institute. The 2-dimensional MWPC with boron ($B_4C$) neutron converter was proved to be useful for neutron beam monitoring, and can be applied to other types of neutron imaging.

• Journal of Korean Society of Environmental Engineers
• /
• v.38 no.11
• /
• pp.603-610
• /
• 2016

This work studies the synthesis of birnessite (${\delta}-MnO_2$), a catalyst of oxidative-coupling reactions, from the powder of spent alkaline manganese batteries (SABP, <8 mesh) and evaluate its reactivity for 1-naphthol (1-NP) removals. Manganese oxides using commercial reagents ($MnSO_4$, $MnCl_2$) and the acid birnessite (A-Bir) by McKenzie method were also synthesized, and their crystallinity and reactivity for 1-NP were compared with one another. 96% Mn and 98% Zn were extracted from SABP by acid leaching at the condition of solid/liquid (S/L) ratio 1:10 in $1.0M\;H_2SO_4+10.5%\;H_2O_2$ at $60^{\circ}C$. From the acid leaching solution, 69% (at pH 8) and 94.3% (pH>13) of Mn were separated by hydroxide precipitation. Optimal OH/Mn mixing ratio (mol/mol) for the manganese oxide (MO) synthesis by alkaline (NaOH) hydrothermal techniques was 6.0. Under this condition, the best 1-NP removal efficiency was observed and XRD analysis confirmed that the MOs are corresponding to birnessite. Kinetic constants (k, at pH 6) for the 1-NP removals of the birnessites obtained from Mn recovered at pH 8 (${Mn^{2+}}_{(aq)}$) and pH>13 ($Mn(OH)_{2(s)}$) are 0.112 and $0.106min^{-1}$, respectively, which are similar to that from $MnSO_4$ reagent ($0.117min^{-1}$). The results indicated that the birnessite prepared from the SABP as a raw material could be used as an oxidative-coupling catalyst for removals of trace phenolic compounds in soil and water, and propose the recycle scheme of SAB for the birnessite synthesis.

• Korean Journal of Soil Science and Fertilizer
• /
• v.45 no.2
• /
• pp.248-252
• /
• 2012

To evaluate the possibility of water plant wastes in composting for agricultural recycling, Phragmites communis (PHRCO), Typha orientalis (TYHOR) and Zizania latifolia (ZIZLA) were used as a compost materials. In composting basin, cumulative oxygen consumptions of the compost used by water plant wastes were rapidly increased at the early stage and slightly decreased in around 15 days. Cumulative oxygen consumptions under different water plant wastes were higher in the order of TYHOR > ZIZLA > PHRCO. Temperature changes during composting process were rapidly increased at the early stage and then slowly decreased to $30{\sim}40^{\circ}C$. The maximum temperatures were higher in the order of ZIZLA ($72.2^{\circ}C$ at 11 days after starting composting) > TYHOR ($70.2^{\circ}C$ at 10 days after starting composting) > PHRCO ($66.5^{\circ}C$ at 7 days after starting composting). Oxygen consumptions at maximum temperature were higher in the order of TYHOR ($12,485mg\;O_2\;kg^{-1}$) > ZIZLA ($12,400mg\;O_2\;kg^{-1}$) > PHRCO ($9,340mg\;O_2\;kg^{-1}$). Organic matter contents, moisture contents and OM/N rates in the compost ranged 39.5~44.8%, 29.6~35.6% and 27.9~32.9, respectively. Considering that water plant waste can supply some of the nutrient requirements of crops and is a valuable fertilizer.