• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2009.04a
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• pp.358-364
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• 2009

본 연구에서는 우리나라 주요 침엽수종인 소나무(Pinus densiflora)와 활엽수종인 굴참나무(Quercus variabilis)의 낙엽에 대해 FTIR(Fourier Transform Infrared) 분광계를 이용하여 배출 연소가스 종류 및 농도를 측정하였다. 실험결과 소나무와 굴참나무 낙엽에서 Carbon monoxide, Carbon dioxide, Acetic acid, Butyl acetate, Ethylene, Methane, Methanol, Nitrogen dioxide, Ammonia, Hydrogen Fluoride, Sulfur dioxide, Hydrogen bromide 등 13개 연소가스가 검출되었고 굴참나무 낙엽에서는 Nitrogen monoxide가 추가로 검출되었다. 방출된 연소가스의 전체 농도는 소나무 낙엽이 굴참나무 낙엽에 비해 4.5배 많이 검출되었다. 특히, 시간가중평균가스농도(TWA : Time-weighted average, ppm) 기준을 초과하는 연소가스는 Carbon monoxide, Carbon dioxide, Butyl acetate가 검출되었고 단시간노출기준(STEL : Short Term Exposure Limit, ppm) 기준을 초과하는 연소가스는 Carbon monoxide, Carbon dioxide로 소나무 및 굴참나무 모두에서 나타났다. 이에 산불에서의 낙엽층 지표화 연소시 전체 가스 방출량의 99% 이상을 차지하고 있는 Carbon monoxide, Carbon dioxide의 건강 위험성이 높은 것으로 나타났다. 하지만, 검출된 다른 건강 위험성 가스의 경우에도 연소물질의 양이 증가할수록 연소가스의 농도가 높아져 건강안정성에 해가 있을 것으로 판단되며 또한 검출된 연소가스 중 나무의 주요구성 원소가 아닌 Bromide, Fluoride 화합물에 대해서는 토양으로부터의 오염 또는 분석과정에서의 노이즈로 인한 검출 등에 대한 보다 면밀한 검토가 필요할 것으로 판단된다.

• Elastomers and Composites
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• v.54 no.3
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• pp.209-219
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• 2019

It is important to analyze crosslink densities of rubber articles because the physical properties are dependent on the crosslink densities. In this paper, analytical techniques for the measurement of crosslink densities of rubber vulcanizates are described. The most widely used method to measure the crosslink density is a swelling method combined with the Flory-Rehner equation. Application of the interaction parameter (${\chi}$) of rubber and swelling solvent is critical because the crosslink density is absolutely dependent on the ${\chi}$ value. Methods for obtaining ${\chi}$ employ not only solubility parameters of the polymer and swelling solvent but also inverse gas chromatography (IGC). The solubilities of rubbers can be obtained using micro differential scanning calorimetry (${\mu}DSC$), intrinsic viscosity measurement, and UV-visible spectroscopy. Nuclear magnetic resonance (NMR) spectroscopy has been also used for the measurement of the crosslink density using the $T_2$ relaxation time, which is determined by spin-spin relaxation in solid-state NMR. For sulfur-cured rubber vulcanizates, crosslink densities according to the crosslink types of mono-, di-, and polysulfides are measured by treating the rubber samples with a chemical probe composed of thiol and amine compounds. Measurement methods of physical crosslinking by filler, crystallization, and ionic bonding have also been introduced.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.3
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• pp.256-261
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• 2019

The use of military lithium batteries in this field accelerates the generation of internal pressure because the active materials, lithium and the electrolyte, react to form sulfur dioxide gas. This also reduces the amount of electrolyte. In this condition, batteries can 'vent' or 'explode' especially when completely discharged. Such venting and explosion can be regarded as a safety accident, as toxic gases and shrapnel are ejected from the batteries which can harm the user. A DTaQ was carried out in 2017 as a quality problem solution project to solve this safety issue. A protection circuit was thereby developed, which included a micro controller unit (MCU) which can stop battery usage when in an over-discharging state by sensing its low-voltage condition. In 2018, this concept was expanded to lithium batteries for the remote controlled ammunition system. This paper reports results of the improved performance.

• Journal of Animal Science and Technology
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• v.61 no.3
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• pp.122-137
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• 2019

Methane, one of the important greenhouse gas, has a higher global warming potential than that of carbon dioxide. Agriculture, especially livestock, is considered as the biggest sector in producing anthropogenic methane. Among livestock, ruminants are the highest emitters of enteric methane. Methanogenesis, a continuous process in the rumen, carried out by archaea either with a hydrogenotrophic pathway that converts hydrogen and carbon dioxide to methane or with methylotrophic pathway, which the substrate for methanogenesis is methyl groups. For accurate estimation of methane from ruminants, three methods have been successfully used in various experiments under different environmental conditions such as respiration chamber, sulfur hexafluoride tracer technique, and the automated head-chamber or GreenFeed system. Methane production and emission from ruminants are increasing day by day with an increase of ruminants which help to meet up the nutrient demands of the increasing human population throughout the world. Several mitigation strategies have been taken separately for methane abatement from ruminant productions such as animal intervention, diet selection, dietary feed additives, probiotics, defaunation, supplementation of fats, oils, organic acids, plant secondary metabolites, etc. However, sustainable mitigation strategies are not established yet. A cumulative approach of accurate enteric methane measurement and existing mitigation strategies with more focusing on the biological reduction of methane emission by direct-fed microbials could be the sustainable methane mitigation approaches.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.7
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• pp.1-7
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• 2021

Restrictions on the emissions of nitrogen oxides, sulfur oxides, carbon dioxide, and particulate matter from marine engines are being tightened. Each of these emissions requires different reduction technologies, which are costly and require many pieces of equipment to meet the requirements. Liquefied natural gas (LNG) fuel has a great advantage in reducing harmful emissions emitted from ships. Therefore, the marine engine application of LNG fuel is significantly increasing in new ship buildings. Accordingly, this study analyzed the internal support structure, insulation type, and fuel supply piping system of a 35 m3 International Maritime Organization C type pressurized storage tank of an LNG-fueled ship. Analysis of the heat transfer characteristics revealed that A304L stainless steel has a lower heat flux than A553 nickel steel, but the effect is not significant. The heat flux of pearlite insulation is much lower than that of vacuum insulation. Moreover, the analysis results of the constraint method of the support ring showed no significant difference. A553 steel containing 9% nickel has a higher strength and lower coefficient of thermal expansion than A304L, making it a suitable material for cryogenic containers.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.4
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• pp.469-477
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• 2021

Safe storage of spent nuclear fuel in deep underground repositories necessitates an understanding of the long-term alteration of metal canisters and buffer materials. A small-scale laboratory alteration test was performed on metal (Cu or Fe) chips embedded in compacted bentonite blocks placed in anaerobic water for 1 year. Lactate, sulfate, and bacteria were separately added to the water to promote biochemical reactions in the system. The bentonite blocks immersed in the water were dismantled after 1 year, showing that their alteration was insignificant. However, the Cu chip exhibited some microscopic etch pits on its surface, wherein a slight sulfur component was detected. Overall, the Fe chip was more corroded than the Cu chip under the same conditions. The secondary phase of the Fe chip was locally found as carbonate materials, such as siderite (FeCO₃) and calcite ((Ca, Fe)CO₃). These secondary products can imply that the local carbonate occurrence on the Fe chip may be initiated and developed by an evolution (alteration) of bentonite and a diffusive provision of biogenic CO₂ gas. These laboratory scale results suggest that the actual long-term alteration of metal canisters/bentonite blocks in the engineered barrier could be possible by microbial activities.

• Clean Technology
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• v.15 no.4
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• pp.239-244
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• 2009

$Mg(OH)_2$ slurry was prepared by using natural mineral brucite mined in Liaoning province in China, and its de-$SO_x$ efficiency was compared with that of $Mg(OH)_2$ slurry prepared by thermal decomposition and hydration of magnesite. The physical and chemical characteristics of $Mg(OH)_2$ Powders prepared from brucite and magnesite were similar. However, the layered plate structure of $Mg(OH)_2$ crystal particles prepared from brucite had grown more stably. The desulfurization efficiency of $Mg(OH)_2$ slurry prepared from brucite was slightly higher than that of magnesite. Brucite may be used as a new absorbent for the desulfurization of flue gas in the future.

• Membrane Journal
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• v.21 no.1
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• pp.22-29
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• 2011

During the maintenance, repair and replacement process of circuit breaker, $SF_6$ reacted with input air in arc discharge, which led to the production of by-product gases (eg, $N_2$, $O_2$, $CF_4$, $SO_2$, $H_2O$, HF, $SOF_2$, $CuF_2$, $WO_3$). Among these various by-product gases, $N_2$, $O_2$, $CF_4$ is major component. Therefore, the effective separation process is necessary to recycle the $SF_6$ gas from the mixture gas containing $N_2$, $O_2$, $CF_4$. In this study, the membrane separation process was applied to recycle the $SF_6$ gas from the mixture gas containing $N_2$, $O_2$, $CF_4$. The concentration of $SF_6$ gas in gas produced from the electric power industry is over than 90 vol%. Therefore, we made the simulated gas containing $N_2$, $O_2$, $CF_4$, $SF_6$ which the concentration of $SF_6$ gas is minimum 90 vol%. From the results of membrane separation process of $SF_6$ gas from $N_2$, $O_2$, $CF_4$ $SF_6$ mixture gases, PSF membrane shown the highest recovery efficiency 92.7%, in $25^{\circ}C$ and 150 cc/min of retentate flow rate. On the other hand, PC membrane shown the highest recovery efficiency 74.8%, in $45^{\circ}C$ and 150 cc/min of retentate flow rate. Also, the highest rejection rate of $N_2$, $O_2$, $CF_4$ is 80, 74 and 58.9% seperately in the same operation condition of highest recovery efficiency. From the results, we supposed the membrane separation process as the effective $SF_6$ separation and recycle process from the mixture gas containing $N_2$, $O_2$, $CF_4$, $SF_6$.

• Journal of the Korea Institute of Building Construction
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• v.17 no.4
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• pp.313-320
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• 2017

Flue gas desulfurization gypsum(FDG) is produced when removing sulfur oxides from combustion gas generated by coal power plant. However, the recycling of FDG is still limited to the certain purposes. In order to expand the possible application of FDG, this study aims to utilize FDG as an activator for ground granulated blast furnace slag. FDG produced by dry- and wet-process were used for the experiments. Slag paste specimens were produced by mixing with deionized water and simulated pore solution, and the role of FDG as an activator for blast furnace slag was evaluated using hydration study by XRD analysis and compressive strength development. According to the results, dry-type FDG was found to work as an activator for blast furnace slag without the presence of soluble alkalis. However, wet-type FDG needs assistance by soluble alkalis in order to work as an activator for blast furnace slag. It was also found that the substitution of dry- and wet-type FDG into blast furnace slag can increase the 28 day compressive strength of slag paste. It is expected that efficient and economical recycling of FDG will be possible if quantitative analysis of strength enhancement according to substitution rate of both dry- and wet-type FDG.

• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.1015-1020
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• 2012

Lignite of low rank coal and petroleum coke of high sulfur content can be high potential energy sources for coal gasification process because of their plentiful supply. The steam gasification of lignite, anthracite, and pet coke has been carried out in both an atmospheric thermobalance reactor and a lab-scale fludized bed reactor (0.02 m i.d. ${\times}$ 0.6 m height). The effects of gasification temperature ($600{\sim}900^{\circ}C$) and partial pressure of steam (0.15~0.95 atm) on the gasification rate and on the heating value of product gas have been investigated. The modified volumetric reaction model was applied to the experimental data to describe the behavior of carbon conversion, and to evaluate kinetic parameters of char gasification. The results shows that higher temperature bring more hydrogen in the product syngas, and thus increased gas heating value. The feed rate of steam is needed to be optimized because an excess steam input would lower the gasification temperature which results in a degradation of fuel quality. The rank of calorific value of the product gas was anthracite > lignite > pet coke. Their obtained calorific value at $900^{\circ}C$ with 95% steam feed were 10.0 > 6.9 > 5.7 $MJ/m^3$. This study indicates that lignite and pet coke has a potential in fuel gas production.