• Environmental Engineering Research
• /
• v.11 no.4
• /
• pp.232-240
• /
• 2006

Polychlorinated naphthalenes (PCNs) formed along with dibenzo-p-dioxin and dibenzofuran products in the slow combustion of dichlorophenols (DCPs) at $600^{\circ}C$ were identified. Each DCP reactant produced a unique set of PCN products. Major PCN congeners observed in the experiments were consistent with products predicted from a mechanism involving an intermediate formed by ortho-ortho carbon coupling of phenoxy radicals; polychlorinated dibenzofurans (PCDFs) are formed from the same interemediate. Tautomerization of the intermediate and $H_2O$ elimination produces PCDFs; alternatively, CO elimination to form dihydrofulvalene and fusion produces naphthalenes. Only trace amounts of tetrachloronaphthalene congeners were formed, suggesting that the preferred PCN formation pathways from chlorinated phenols involve loss of chlorine. 3,4-DCP produced the largest yields of PCDF and PCN products with two or more chlorine substituents. 2,6-DCP did not produce tri- or tetra-chlorinated PCDF or PCN congeners. It did produce 1,8-DCN, however, which could not be explained.

• Journal of Korean Elementary Science Education
• /
• v.27 no.3
• /
• pp.244-251
• /
• 2008

One of the problems with testing for the presence of $CO_2$ is that the results are not visible. In order to over-come this weak point, a new testing method was developed with BTB indicator equipment, that made the gas visible. After that, the experiment was performed and tested the effects of the new visible equipment. The visible equipment could be adapted to regular class use successfully. Also, it was effective in that it reduced waste of gas, minimized danger potential through use of $CO_2$ canisters and candle-sticks, and also increased knowledge about indicators. The new experimental method and equipment affected the students' interest. It is possible that the students' positive participation was due to their interest in the new apparatus and application of the visual senses. The new system was tested fer its effects on teaching content and helping to produce sustained memory of the content. There were no significant differences between the groups in terms of content learning on initial content memory. However, when students in both groups were tested 4 months later, the visual experiment group sustained memory performance, while the other group showed a significant decrease. Generally, boys score higher than girls in terms of interest and participation in experimental activities. In this case, however, there were no difference between groups. It may have been due to introduction of new equipment and different methods from the textbooks. So, this could increase participation in science using various experiments.

• Journal of Environmental Science International
• /
• v.8 no.1
• /
• pp.75-81
• /
• 1999

In recent years increasing production and disposal of wastewater have caused an accelerated eutrophication of receiving waters. Therefore, in order to alleviate the detrimental impact of wastewater discharge, there is an increasing demand for removing the main nutrients, nitrogen and phosphorus, as well as the organic content of the waste water prior to disposal. This is effectively achieved by extended conventional treatment technology. However, the working expenses and energy requirements of such advanced treatment systems are rather high. So in a sparsely populated rural community is required development of wastewater treatment system combined with the regional characteristics. In this study, the systems are planted with Reeds and Amaryllis In A.C and estimated purification potential of system. The results obtained are as follows. BOD removal rate is 20% in the early stage, the last removal rate is 35% in A.C process and is 65% in Amaryllis+A.C process and is 50% in Reed+A.C process. T-N removal rate by Amaryllis is average 2.6g/$m^3$ㆍd, T-N removal rate by Reed is average 1.76g/$m^3$ㆍd. T-P removal rate by Amaryllis is average 0.27g/$m^3$ㆍd, T-P removal rate by Reed is average 0.25g/$m^3$ㆍd. BOD removal rate constant with retention time is 1.4494(1/d), T-N removal rate constant is 0.5428(1/d), T-P removal rate constant is 0.5287(1/d).

• Proceedings of the KSME Conference
• /
• 2008.11b
• /
• pp.2940-2945
• /
• 2008

The scale of 2.4 MW MCFC was taken to construct a high-efficiency and economical power generation system without CO2 emission into the atmosphere for utilizing its exhaust gas. The conventional steam turbine power generation system (STGS) was evaluated and the net generated power (NGP) was estimated to be only 133 kW and the STGS is not economically feasible. A CO2-caputuring repowering system was proposed, where low temperature steam (LTS) produced at HRSG by using exhaust gas from MCFC is utilized as a main working fluid of a gas turbine, and the temperature of LTS was raised by combusting fuel in a combustor by using pure oxygen, not the air. It has been shown that NGP of the proposed system is 264 kW, and CO2 reduction amount is 608 t-CO2/y, compared to 306 t-CO2/y of STGS. The CO2 reduction cost was estimated to be negligible small, even when the costs of oxygen production and CO2 liquefaction facilities etc. were taken into account.

• Nuclear Engineering and Technology
• /
• v.47 no.6
• /
• pp.647-661
• /
• 2015

The supercritical $CO_2$ (S-$CO_2$) Brayton cycle has recently been gaining a lot of attention for application to next generation nuclear reactors. The advantages of the S-$CO_2$ cycle are high efficiency in the mild turbine inlet temperature region and a small physical footprint with a simple layout, compact turbomachinery, and heat exchangers. Several heat sources including nuclear, fossil fuel, waste heat, and renewable heat sources such as solar thermal or fuel cells are potential application areas of the S-$CO_2$ cycle. In this paper, the current development progress of the S-$CO_2$ cycle is introduced. Moreover, a quick comparison of various S-$CO_2$ layouts is presented in terms of cycle performance.

• Journal of Hydrogen and New Energy
• /
• v.27 no.2
• /
• pp.135-143
• /
• 2016

Biogas is a renewable fuel from anaerobic digestion of organic matters such as sewage sludge, manure and food waste. Raw biogas consists mainly of methane, carbon dioxide, hydrogen sulfide, and water. Biogas may also contain other impurities such as siloxanes, halogenated hydrocarbons, aromatic hydrocarbons. Efficient power technologies such as fuel cell demand ultra-low concentration of containments in the biogas feed, imposing stringent requirements on fuel purification technology. Biogas is upgraded from pressure swing adsorption after biogas purification process which consists of water, $H_2S$ and siloxane removal. A polymer electrolyte membrane fuel cell power plant is designed to operate on reformate produced from upgraded biogas by steam reformer.

• Journal of the Korean Society of Safety
• /
• v.8 no.1
• /
• pp.29-34
• /
• 1993

Two major hazardous gases. SOx and NOx. are emissioned from fossile fuels. SOx has been removed when oil is refined but NOx hasn't. So NOx is very serious problem in air pollution now There are several technologies to remove NOx. e.g. cooling method. scrubbers method. combustion method, polymer membrane method and adsorbent methods. Polymer membrane and adsorbent methods have good economic merit in removal systems of low content hazard gases. Traditional absorbents are porous silicas, aluminas. active carbon and zeolites. But these absorbents act only physisorption which has less removal performance than chemisorption. In this study. polymeric absorbent which has chemisorption as well as physisorption was analyzed about chemical structure and experimented about optimum operation conditions. The results showed that the chemical structure of the polymeric absorbent was expected as polystyrene having -N-CH$_2$COOH absorbent was revealed about 310$m^2$/g. The molar ratio of absored NO to charged NO in absorption experiments was shown 60% of the polymeric absorbent and 45% of zeolite absorbent at 3$0^{\circ}C$.

• Journal of Energy Engineering
• /
• v.25 no.2
• /
• pp.65-78
• /
• 2016

Initial studies of the photocatalyst has been developed from the field relating to the conversion and storage of solar energy. Recently, the study of the various organic decomposition compound and the water purification and waste water treatment by ultraviolet irradiation in the presence of light or a photocatalyst are being actively investigated. In addition, the oxidized material-carbon nanotubes, graphene-nanocomposites have been studied. Such a complex is suitable as a material constituting the solar cells and photolysis nanoelectronics, including the flexible element due to thermal and chemical stability.

• Korean Journal of Food Science and Technology
• /
• v.9 no.1
• /
• pp.1-9
• /
• 1977

A bacterium strain (K-173-10) which was isolated from waste soil of Korea brewing factory, could be grown on acetate as the sole carbon source and accumulated a considerable amount of L-glutamic acid in the medium. This strain was identified as the new species Brevibacterium ammoniagenes. This study was concerned not only with the culture condition for the production of L-glutamic acid and the cell growth, but also with the effects on concentration of various kind of organic substances, growth factors and penicillin. The results obtained were summarized as follow; 1. It was found that the concentrations of acetate and ammonium ions affected the growth of the bacterium as well as its L-glutamate accumulation. The optimum conditions of the composition of grown media for the growth of the bacterium and its glutamic acid production was found to be 40 g/l of total acetate, $100\;{\mu}g/l$ thiamine, $0.5\;{\mu}g/l$ biotin and $1{\sim}2g/l$ corn steep liquor as the growth factors. 2. Organic acid such as succinic acid, malic acid and ${\alpha}-ketoglutaric$ acid inhibited the cell growth as well as its L-glutamic acid production. 3. The penicillin (20 units/ml) stimulated the production of glutamic acid at appropriate incubation period. 4. It was found that this strain could grow in the presence of urea and ammonium acetate but not in other nitrogen sources.

• Journal of Life Science
• /
• v.12 no.3
• /
• pp.288-293
• /
• 2002

A reactive dye-degrading bacterium was isolated from textile waste water and it was identified as Stenotrophomonas maltophilia based on its biochemical characteristics. The effects of additional carbon and nitrogen sources were investigated for the development of an optimal medium for biodegradation of Remazol Black B by 5. maltophilia. The optimal pH and temperature were determined to be 6.5 and 3$0^{\circ}C$, respectively. Remazol Black B with the initial concentration of 50 ppm could be degraded up to 86% within 28 h.