• Journal of Korean Society for Atmospheric Environment
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• v.2 no.1
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• pp.11-21
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• 1986

The study was performed to investigate the effects of gaseous imission of sulfur dioxide and hydrogen fluoride on the growth of rice plant under stressed field conditions. The plants were cultivated in normal paddy fields where are 88 industrial plants operating with 285 smoke stacks emitting pollutants. There has been a number of reported studies (1, 3, 11, 19, 20) which deal with rice plant damages by air pollution under a simulated exposure experimental condition. Furthermore, these experiments were conducted to examine effects of a single pollutant on the plant. Furthermore, these experiments were conducted to examine effects of a single pollutant on the plant. In korea, however, there is no study reported in literature with respect to the in-situ dose-response relationship between rice pant reduction in yields and air pollution. This study is specifically dealt with multiple effects of sulfur dioxde and hydrogen fluoride on various plant growth indicators such as leaf damage, culm height, weight of grain, panicles per hill, spikelets per panicle and percent fertility.It appears that there is a good correlation between ambient concentrations of sulfur oxides and sulfur contents found in leaves with an average correlation coefficient of 0.868 within a 1% significance level. It is interesting to note that a better multiple correlation was found between percent leaf damage and sulfur and fluoride contentd found in leaf with a significance of 1% level. The yearly correlation coefficient ranges from 0.963 to 0.987 with an average being 0.971. It is, therefore, believed that a percent leaf damage may serve as a single indicator of pollutional damages to rice plant cultivating in fields. Regarding other factors to the diminution of rice plant growth in polluted atmosphere, it appears that a significant correlation to culm length and dry weight of grain with a 1% significance level whereas T/R ratio has a good correlation with lead damage within 5% significance level. An evaluation of data observed has demonstrated that both panicles per hill and percent fertility are significantly affected by air pollutants. As expected, hydrogen fluoride has more effects than sulfur oxide. It is, however, interesting to note that spikelets per panicles has slightly been affected while no indication of effects on 1000-grain-weight has been observed. This may lead to a conclusion that a reduction in yield of rice under polluted field conditions may have more been caused by the diminution of panicles per hill and percent fertility rather than by the diminution of spikelets per panicle and grain weight.

• Journal of Animal Science and Technology
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• v.60 no.11
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• pp.27.1-27.8
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• 2018

Background: Enteric methane ($CH_4$) accounts for about 70% of total $CH_4$ emissions from the ruminant animals. Researchers are exploring ways to mitigate enteric $CH_4$ emissions from ruminants. Recently, nano zinc oxide (nZnO) has shown potential in reducing $CH_4$ and hydrogen sulfide ($H_2S$) production from the liquid manure under anaerobic storage conditions. Four different levels of nZnO and two types of feed were mixed with rumen fluid to investigate the efficacy of nZnO in mitigating gaseous production. Methods: All experiments with four replicates were conducted in batches in 250 mL glass bottles paired with the ANKOM$^{RF}$ wireless gas production monitoring system. Gas production was monitored continuously for 72 h at a constant temperature of $39{\pm}1^{\circ}C$ in a water bath. Headspace gas samples were collected using gas-tight syringes from the Tedlar bags connected to the glass bottles and analyzed for greenhouse gases ($CH_4$ and carbon dioxide-$CO_2$) and $H_2S$ concentrations. $CH_4$ and $CO_2$ gas concentrations were analyzed using an SRI-8610 Gas Chromatograph and $H_2S$ concentrations were measured using a Jerome 631X meter. At the same time, substrate (i.e. mixed rumen fluid+ NP treatment+ feed composite) samples were collected from the glass bottles at the beginning and at the end of an experiment for bacterial counts, and volatile fatty acids (VFAs) analysis. Results: Compared to the control treatment the $H_2S$ and GHGs concentration reduction after 72 h of the tested nZnO levels varied between 4.89 to 53.65%. Additionally, 0.47 to 22.21% microbial population reduction was observed from the applied nZnO treatments. Application of nZnO at a rate of $1000{\mu}g\;g^{-1}$ have exhibited the highest amount of concentration reductions for all three gases and microbial population. Conclusion: Results suggest that both 500 and $1000{\mu}g\;g^{-1}$ nZnO application levels have the potential to reduce GHG and $H_2S$ concentrations.

• Clean Technology
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• v.27 no.2
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• pp.139-145
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• 2021

The purpose of this study is to recover valuable metals from spent batteries using a dry process. We focused on the effect of the smelting temperature on the composition of recovered solid and liquid products and collected gaseous products. After removal of the cover, the spent battery was left in NaCl solution and discharged. Then, the spent battery was made into a powder form through a crushing process. The smelting of the spent battery was performed in a tubular electric furnace in an oxygen atmosphere. For spent lithium-ion batteries, the recovery yield of the solid product was 80.1 wt% at a reaction temperature of 850 ℃, and the final product had 27.2 wt% of cobalt as well as other metals such as lithium, copper, and aluminum. Spent nickel-hydrogen batteries had a recovery yield of 99.2 wt% at a reaction temperature of 850 ℃ with about 37.6 wt% of nickel and other metals including iron. For spent nickel-cadmium batteries, the yield decreased to 65.4 wt% because of evaporation with increasing temperature. At 1050 ℃, the recovered metals were nickel (41 wt%) and cadmium (12.9 wt%). Benzene and toluene, which were not detected with the other secondary waste batteries, were detected in the gaseous product. The results of this study can be used as basic data for future research on the dry recycling process of spent secondary batteries.

• Journal of Animal Science and Technology
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• v.46 no.2
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• pp.283-294
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• 2004

Air quality in the livestock waste compost pilot plant at the Colligate Livestock Station was assessed to quantity the emissions of aerial contaminants and evaluate the degree of correlation between them for different operation strategies; with the ventilation types and agitation of compost pile, in this study. The parameters analyzed to reflect the level of air quality in the livestock waste compost pilot plant were the gaseous contaminants; ammonia, hydrogen sulfide, and odor concentration, the particulate contaminants; inhalable dust and respirable dust, and the biological contaminants; total airborne bacteria and fungi. The mean concentrations of ammonia, hydrogen sulfide, and odor concentration in the compost pilot plant without agitation were 2.45ppm, 19.96ppb, and 15.8 when it was naturally ventilated, and 7.61ppm, 31.36ppb, and 30.2 when mechanically ventilated. Those with agitation were 5.50ppm, 14.69ppb, and 46.4 when naturally ventilated, and 30.12ppm, 39.91ppb, and 205.5 when mechanically ventilated. The mean concentrations of inhalable and respirable dust in the compost pilot plant without agitation were 368.6${\mu}g$/$m^3$ and 96.0${\mu}g$/$m^3$ with natural ventilation, and 283.9${\mu}g$/$m^3$ and 119.5${\mu}g$/$m^3$ with mechanical ventilation. They were also observed with agitation to 208.7${\mu}g$/$m^3$ and 139.8${\mu}g$/$m^3$ with natural ventilation, and 209.2${\mu}g$/$m^3$ and 131.7${\mu}g$/$m^3$ with mechanical ventilation. Averaged concentrations of total airborne bacteria and fungi in the compost pilot plant without agitation were observed to 28,673cfu/$m^3$ and 22,507cfu/$m^3$ with natural ventilation, and 7,462cfu/$m^3$ and 3,228cfu/$m^3$ with mechanical ventilation. They were also observed with agitation to 19,592cfu/$m^3$ and 26,376cfu/$m^3$ with the natural ventilation, and 18,645cfu/$m^3$ and 24,581cfu/$m^3$ with the mechanical ventilation. It showed that the emission rates of gaseous pollutants, such as ammonia, hydrogen sulfide, and odor concentration, in the compost pilot plant operated with the mechanical ventilation and with the agitation of compost pile were higher than those with the natural ventilation and without the agitation. While the concentrations of inhalable dust and total airborne bacteria in the compost pilot plant with the natural ventilation and with the agitation, the concentrations of respirable dust and total airborne fungi in the compost pilot plant with the mechanical ventilation and agitation were higher than those with the natural ventilation and without the agitation of compost pile. It was statistically proved that indoor temperature and relative humidity affected the release of particulates and biological pollutants, and ammonia and hydrogen sulfide were believed primary malodorous compounds emitted from the compost pilot plant.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.107-107
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• 2010

Hydrogen is an alternative fuel for the future energy which can reduce pollutants and greenhouse gases. Synthesis gas have played an important role of synthesizing the valuable chemical compound, for example methanol, DME and GTL chemicals. Renewable biomass feedstocks can be potentially used for fuels and chemical production. Current thermal processing techniques such as fast pyrolysis, slow pyrolysis, and gasification tend to generate products with a large slate of compounds. Lignocellulose feedstocks such as forest residues are promising for the production of bio-oil and synthesis gas. Pyrolysis and gasification was investigated using thermogravimetric analyzer (TGA) and bubbling fluidized bed gasification reactor to utilize forest woody biomass. Most of the materials decomposed between $320^{\circ}C$ and $380^{\circ}C$ at heating rates of $5{\sim}20^{\circ}C/min$ in thermogravimetric analysis. Bubbling fluidized bed reactor were use to study gasification characteristics, and the effects of reaction temperature, residence time and feedstocks on gas yields and selectivities were investigated. With increasing temperature from $750^{\circ}C$ to $850^{\circ}C$, the yield of char decreased, whereas the yield of gas increased. The gaseous products consisted of mostly CO, CO2, H2 and a small fraction of C1-C4 hydrocarbons.

• Journal of Korean Elementary Science Education
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• v.26 no.4
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• pp.359-371
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• 2007

The purpose of this study was to investigate elementary school students' conceptions of gas and analyse the type of alternative conceptions of gas which students constructed. To appreciate the conceptions formed by elementary school students on this topic, 173 sixth grade students from an elementary school located in Suwon participated in this study. Additionally, their conceptions and their alternative conceptions of gas represented by the questionnaires were analyzed. The questionnaires consisted of 11 questions related to the conception of gas. To analyze the types of alternative conceptions which presented themselves, constructed prototypes were generated by interviewing the students themselves. From our results, we suggest that sixth grade elementary school students have various conceptions of gas and tend to think that gas is weighty, and that gaseous volume decreases by pressure. However, their conceptions of gas melting in water were very low, as only about 16% of students were aware of this scientific conception. Students who did not understand precisely the conception of the nature of oxygen, carbon dioxide and hydrogen were over 20%. The results of the interviews showed that the construction of alternative conceptions of gas was affected by various and complex causes.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.27.1-27.1
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• 2011

The recent extensive research of one-dimensional (1D) nanostructures such as nanowires (NWs) and nanotubes (NTs) has been the driving force to fabricate new kinds of nanoscale devices in electronics, optics and bioengineering. We attempt to produce silicon oxide nanowires (SiOxNWs) in a simple way without complicate deposition process, gaseous Si containing precursors, or starting material of $SiO_2$. Nickel (Ni) nanoparticles (NPs) were applied on Si wafer and thermally treated in a furnace. The temperature in the furnace was kept in the ranges between 900 and $1,100^{\circ}C$ and a mixture of nitrogen ($N_2$) and hydrogen ($H_2$) flowed through the furnace. The SiOxNWs had widths ranging from 100 to 200 nm with length extending up to ~10 ${\mu}m$ and their structure was amorphous. Ni NPs were acted as catalysts. Since there were no other Si materials introduced into the furnace, the Si wafer was the only Si sources for the growth of SiOxNWs. When the Si wafer with deposition of Ni NPs was heated, the liquid Ni-Si alloy droplets were formed. The droplets as the nucleation sites induce an initiation of the growth of SiOxNWs and absorb oxygen easily. As the droplets became supersaturated, the SiOxNWs were grown, by the reaction between Si and O and continuously dissolving Si and O onto NPs. Photoluminescence (PL) showed that blue emission spectrum was centered at the wavelength of 450 nm (2.76 eV). The details of growth mechanism of SiOxNWs and the effect of Ni NPs on the formation of SiOxNWs will be presented.

• Journal of Sensor Science and Technology
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• v.23 no.5
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• pp.342-348
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• 2014

This paper introduced a novel multi-gas sensor detector with simple signal processing algorithm. This device was evaluated by investigating the characteristics of combustible materials using fire-generated smell and smoke. Plural sensors including TGS821, TGS2442, and TGS260X were equipped to detect carbon monoxide, hydrogen gas, and gaseous air contaminants which exist in cigarette smoke, respectively. Signal processing algorithm based on the difference of response times in fire-generated gases was implemented with early and accurately fire detection from multiple gas sensing signals. All fire experiments were performed in a virtual fire chamber. The cigarette, cotton fiber, hair, polyester fiber, nylon fiber, paper, and bread were used as a combustible material. This analyzing software and sensor controlling algorithm were embedded into 8-bit micro-controller. Also the detected multiple gas sensor signals were simultaneously transferred to the personnel computer. The results showed that the air pollution detecting sensor could be used as an efficient sensor for a fire detector which showed high sensitivity in volatile organic compounds. The proposed detecting algorithm may give more information to us compared to the conventional method for determining a threshold value. A fire detecting device with a multi-sensor is likely to be a practical and commercial technology, which can be used for domestic and office environment as well as has a comparatively low cost and high efficiency compared to the conventional device.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.4
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• pp.1-10
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• 2006

In this paper, a calculation method of the thermodynamic parameters of cryogenic propellant is proposed when a cryogenic propellant tank is pressurized by gaseous helium(GHe) bubbling. Temperature of cryogenic propellant and mass of dissolved GHe into propellant were analyzed at the various operation of pressurization of tile liquid oxygen(LOX) and hydrogen($LH_2$) tank using helium bubbling. It was evaluated how the GHe bubbling influences to the thermodynamic parameters of LOX and $LH_2$ with results of the analysis. With the proposed calculation method, It will be able to confirm the feasibility of GHe bubbling as a pressurization system of cryogenic propellant tank and to optimize the pressurization system using GHe bubbling.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.3
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• pp.1-7
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• 2018

A combustion test for a supersonic combustor was conducted using a direct-connected type supersonic combustor test facility. The facility was verified for the capability of simulating required flow conditions. The test condition was maintained at Mach 2.0, $915^{\circ}C$ and 496 kPa for 15 s. Using gaseous hydrogen as the fuel, the combustor model was also tested for its ignition and flame holding capability at the fuel equivalence ratio of 0.12. Combustion efficiency was 71%, and the supersonic flow regime was obtained at this test condition.