• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.626-631
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• 2019

The policy-making and technological development for the supply expansion of eco-friendly automobiles has been continuing, but the internal combustion engines still accounts for about 95%. Also, in order to meet the stricter emission regulations of internal combustion engines based on fossil fuels, the proportion of after-treatments for vehicles and (ocean going) vessels is gradually increasing. This study is a basic study for the post-Euro-VI exhaust response of CNG buses, and it is to investigate the basic characteristics according to Pd substitution transition metal effect, catalyst volume effect and space velocity. A catalysts was prepared and tested using a model gas reactor. The NGOC catalyst with 3Pd exhibited the highest catalytic activity with 22% at $300^{\circ}C$, 48% at $350^{\circ}C$ and about 75% at $500^{\circ}C$. 3Co NGOC containing 3wt% of transition metal was excellent in oxidation ability, and it was small in size of 2nm, and the degree of catalyst dispersion was improved and de-NO/CO conversion was high. The volume of the NGOC-LNT-SCR catalyst system was optimal in the combination of 1.5+0.5+0.5 with a total score of 165, considering $de-CH_4/NOx$ performance and catalyst cost. For SV $14,000h^{-1}$, the $CH_4$ reduction performance was the highest at about 20%, while the SV $56,000h^{-1}$ was the lowest at about 5%. If the space velocity is small, the flow velocity decreases and the time remaining in the catalyst volume become long, so that the harmful gas was reduced.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.708-715
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• 2017

Recently, in order to meet the stricter emission regulations, the proportion of after-treatments for vehicles and vessels has been increasing gradually. The objective of this study is to investigate the improvement of $CH_4$ reduction ability of natural gas oxidation catalyst (NGOC), which reduces toxic gases emitted from CNG buses. Thirteen NGOCs were prepared, and the conversion performance of noxious gases according to the type of supports, the loading amount of noble metal, and surfactant and aging were determined. Support Zeolite supported on No. 3 $NGOC(1Pt-1Pd-3MgO-3CeO_2/(46TiO_2+23Al_2O_3+23Zeolite)$ is an anionic alkali metal/earth metal component that improved the oxidation reactivity between CO and NO and noble metal dispersion, and thus enhanced the $CH_4$ reduction ability. As the loading amount of Pd, a noble metal with a high selectivity to $CH_4$, was increased, the number of reaction sites was increased and the ability to reduce $CH_4$ was improved. No. 11 $NGOC(1Pt-1Pd-3MgO-3CeO_2/(Z20+Al80)$(pH=8.5), to which nitrate surfactant had been added, exhibited well dispersed catalyst particles with no agglomeration and improved the $CH_4$ reduction ability by 5-15%. The $NGOC(2Pt-2Pd-3Cr-3MgO/90Al_2O_3)$(48h aging), which was mildly thermal aged for 48h, increased the $CH_4$ reduction ability to about 10% or less as compared with No. 12 NGOC(Fresh).

• Journal of ILASS-Korea
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• v.17 no.3
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• pp.152-157
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• 2012

This investigation decribes the effect of the combustion and emission characteristics of HCNG engine according to the high purity hydrogen contents. The HCNG fuel was made by the mixture with a high purity hydrogen ($H_2$) and a natural gas. The test vehicle was applied to the bi-fuel (Gasoline and CNG) system and this system was modified from the fuel supply and fuel tank. In addition, the three premixed HCNG fuels with mixed rate of 10, 20 and 30% of hydrogen were used to maintain the safety. In order to analyze the combustion characteristics of HCNG and CNG, the fuel was injected in the combustor with constant volume. The exhaust emission from light duty vehicle with bi-fuel system was analyzed by a chassis dynamometer and emission analyzer. From these results, the reduction rate of NOx emission increased in the HCNG fuel and emission amount of THC and CO shows a similar level with CNG fuel. This study can be utilized the basic data for the development of a new business plans related with HCNG engines.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.5
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• pp.58-65
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• 2004

A cylindrical constant volume combustion chamber was used to investigate the combustion characteristics of stratified methane-air mixture under several initial charge conditions in the author's previous reports. The results showed that the improvement of thermal efficiency and reduction of heat loss was realized simultaneously by using 2-stage injection method. This paper deals with the reason why the stratified combustion has showed better combustion rate through the measurement and analysis of chemiluminescence of C $H^{*}$ and $C_{2}$$^{*}$ radicals. An optic fiber bundle is used to measure the local emission of C $H^{*}$ and $C_{2}$$^{*}$ radicals to map the relationship between the excess air ratio and local radical intensity ratio in the combustion vessel at 5 mm apart form the geometric center. The results show that there exist a relationship between the intensity ratio and the air-fuel ratio. It is revealed that the improvement of combustion rate in a lean-stratified mixture is realized through the 2-stage injection method. method.

• Journal of the Korean Institute of Gas
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• v.17 no.5
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• pp.1-7
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• 2013

In this study, simulation work of HCNG refueling system was performed. The hydrogen was produced from steam reforming process by natural gas. The conversion of natural gas is increased as SCR is increased. but it was no significant difference more than 3 of SCR and fuel throughput is increased as GHSV is increased. Both conversion and fuel throughput levels was optimized when the $1700h^{-1}$ of GHSV. CNG was compressed from low pressure natural gas. For the mixing of $H_2$ and CNG is mixed with the high pressure conditions such as 400bar of $H_2$ and 250bar of natural gas. Single-stage compression was required more power than multi stage. So, multi stage compression was suggested for high pressure compression. We calculated the intermediate pressure to minimize total required power of compressors. The intermediate pressure for $H_2$ and natural gas were derived at 61 and 65 bar, respectively.

• Journal of Life Science
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• v.18 no.10
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• pp.1420-1425
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• 2008

This study was conducted to investigate the fermentation characteristics of cheonggukjang prepared with soybean germinated under light condition. The moisture content and pH of cheonggukjang made with soybean germinated under light condition (CGL) were higher than that of cheonggukjang made with non-germinated soybean (CNG). The color of CGL was darker than that of CNG and cheonggukjang made with soybean germinated under dark condition (CGD). The number of live bacteria in the CGL ($10.7{\pm}0.3\;\log\;CFU/g$) and CGD ($10.7{\pm}0.4\;\log\;CFU/g$) was higher than that of CNG ($9.7{\pm}0.4\;\log\;CFU/g$). The levels of isoflavone in CGL, CGD and CNG were 2,038.0, 1,993.6 and 1,747.0 ug/g, respectively. There were no significant differences in the appearance, aroma, taste and overall acceptability of the cheonggukjang made with different germination conditions. Therefore, it was expected that the cheonggukjang prepared with soybean germinated under light condition could be practically used as a new fermented food.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.2
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• pp.84-91
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• 2006

A heavy duty hydrogen-natural gas fueled engine can obtain stable operation at ultra lean conditions and reduce emissions extremely. Reduction of $CO_2$ in its engine is one of the most benefit. In this study, rate of hydrogen addition($R_{dH2}$) and compression ratio($\varepsilon$) were investigated including performance of this engine. As results, it was found that phenomenon of pressure oscillation when increasing $R_{dH2}$ and $\varepsilon$, it means occurring knock. It consider that pressure oscillation was increased due to fast burning speed of hydrogen. Even if same compression ratio, pressure oscillation was remarkable increased according to increasing $R_{dH2}$. Therefore, limit compression ratio of knock occurring was reduced by increasing $R_{dH2}$.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.569-572
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• 2007

천연가스의 주요 구성성분은 메탄, 에탄, 프로판으로 99%이상 차지하고 있으며 천연가스 하이드레이트(NGH)는 압축천연가스(CNG)에 비해 체적당 질량이 크고 액화천연가스(LNG) 보다 상대적으로 유리한 온도 및 압력조건으로 인해 천연가스의 경제적인 저장 및 수송 수단으로 주목 받고 있다. $CH_4$ - $C_2H_6$, $CH_4$ - $C_3H_8$ 혼합가스 하이드레이트의 제조시 반응시간에 따른 하이드레이트의 거동을 관찰하였으며 생성조건의 변화에 따른 하이드레이트의 생성속도를 비교하였다. 하이드레이트의 생성이 진행될 때 기상에서의 $C_2H_6$, $C_3H_8$의 몰 비는 감소함을 보여주었고 이러한 변화는 $CH_4$ - $C_3H_8$가 $CH_4$ - $C_2H_6$보다 더욱 빠르게 진행되었다. 또한 생성된 하이드레이트의 해리과정이 진행될 때 역시 서로 다른 해리속도에 의해 조성의 변화를 관찰 할 수 있었다.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.6
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• pp.649-656
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• 2017

At present, hydrogen is emerging as a future energy source based on environment-friendly aspect, creation of new industry, and enhancement of domestic energy security. In accordance with it, the world's leading automobile companies are focusing on the development and commercialization of hydrogen electric vehicle technology, and each country is strengthening its hydrogen fueling station deployment strategy for its own country. Furthermore, the supply of hydrogen fueling stations is actively promoting under national support. More than 500 hydrogen fueling stations are being constructed, operated and planned around the world. The introduction of hydrogen energy is also progressing in Korea, by announcing road-map to supply hydrogen electric vehicles and hydrogen fueling stations by year. However, there is insufficient discussion on the capacity of hydrogen fueling station in Korea. Therefore, this study suggests the optimum capacity of hydrogen fuelling station for domestic hydrogen economy.

• International Journal of Automotive Technology
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• v.4 no.1
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• pp.9-19
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• 2003

Exhaust emissions were characterized for a fleet of 10 alternative-fuel vehicles (AFVx) including 5 compressed natural gas (CNG) vehicles. 3 liquefied petroleum gas (LPG) vehicles and 2 85% methanol/15% California Phase 2 gasoline (M85) vehicles. In addition to the standard regulated emissions and detailed speciation of organic gas compounds, Fourier Transform Infrared Spectroscopy (FTIR) was used to measure ammonia (NH$_3$) and nitrous oxide ($N_2$O) emissions. NH$_3$, emissions averaged 0.124 g/mi for the vehicle fleet with a range from <0.004 to 0.540 g/mi. $N_2$O emissions averaged 0.022 g/mi over the vehicle fleet with range from <0.002 to 0.077 g/mi. Modal emissions showed that both NH$_3$, and $N_2$O emissions began during catalyst light-off and continued as the catalyst reached its operating temperature. $N_2$O emissions primarily were formed during the initial stages of catalyst light-off. Detailed speciation measurements showed that the principal component of the fuel was also the primary organic gas species found in the exhaust. In particular, methane, propane and methanol composed on average 93%, 79%, and 75% of the organic gas emissions, respectively, for the CNG, LPG. and M85 vehicles.