• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.145-146
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• 2001

1999년도 전국의 대기오염물질 배출량은 371만톤으로 이 중 자동차 배출가스가 약42%를 차지하고 있다. 특히 서울등의 대도시의 경우 자동차공해 비중이 약80%를 넘어서기도 하여, 시민 건강에 대한 우려의 목소리가 높다. 자동차 배출 오염물질은 휘발유, 가스연료를 사용할 경우에는 일산화탄소(CO), 탄화수소(HC), 질소산화물(NOx) 및 미량의 황산화물이 주로 발생되며, 경유를 사용하는 경우에는 추가적인 PM이 배출된다. (중략)

• Journal of Aerospace System Engineering
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• v.3 no.2
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• pp.20-23
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• 2009

The structural analysis of liquid rocket engine was performed in the case of sinusoidal vibration load to verify structural safety. The finite element model is composed with main liquid rocket engine components, combustion chamber, turbopump, gas-generator, pyro-starter, main pipes, main valve, heat-exchanger, gimbal-mount and brackets. Natural vibration mode analysis and structural analysis for sinusoidal vibration load were performed. The natural mode frequency of liquid rocket engine is twice than that of launch vehicle. In the case of stress result of sinusoidal vibration load, the part of maximum stress has 1.4 margin, so the engine structure is safe for sinusoidal vibration load.

• Journal of the Korean Institute of Gas
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• v.13 no.2
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• pp.41-48
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• 2009

I collected the cases of CNG vehicle accidents which had happened for 30 years and analyzed the causes of the accidents according to each type of cylinders. There are about six accidents including three cylinder explosion accidents due to bad heat treatment, one composite damage, one CNG vehicle fire, and one fuel piping accident owing to the poor maintenance. When looking into the cylinder types involved in the accidents and the causes, 29% of the cylinder accidents are Type I and 24% Type IV, 16% Type II, and 14% Type III. 37% of the accidents are caused by the defects of the raw materials and the errors of a manufacturing process, 16% by the stress corrosion cracking as a result of the repetitive use, 15% by the cylinder's explosion on account of the malfunction of PRD(Pressure Relief Device) and the overpressure. The remainders of the causes are fire and unknown causes. Therefore, cylinder manufacturers have to strengthen quality management of raw materials and manufacturing process and painting regardless of each type of cylinder. Also bus operators need to make an effort to keep safety condition through every day check.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.4
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• pp.349-354
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• 2010

Fuel cells have attracted enormous interest as new power sources because the cells can be used to solve the problem of environmental pollution as well as the natural-resource exhaustion problem. In this study, hydrogen-gas flow in microchannels of different shapes was numerically analyzed to improve the efficiency of a microfuel cell. Flow characteristics in six microchannels of different shapes but under identical boundary conditions were simulated. The analysis result shows that the flow characteristics such as velocity, uniformity, and flow rate, greatly depend upon the channel shape. This implies that the efficiency of microfuel cell can be expected to be increased by adopting the optimal configuration of channel shape for hydrogen-gas flow. The experimental results show that power density of a PEMFC with a microflow channel is higher than that of a PEMFC without a microflow channel; however, a durable catalyst is required in MEA.

• New & Renewable Energy
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• v.7 no.3
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• pp.17-28
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• 2011

Biogas production and utilization are an emerging alternative energy technology. Biogas is produced from the biological breakdown of organic matter through anaerobic digestion. Biogas can be utilized for various energy sectors such as space heating, electricity generation and vehicle fuel. Especially, to be utilized as vehicle fuel, raw biogas needs to be upgraded that is mainly the removal of carbon dioxide to increase the methane content up to more than 95 ~ 97 vol% in some cases, similar to the composition of fossil-based natural gas. Usage of Biogas as a fuel of vehicles have an effect of reducing $CO_2$ emission compared to fossil fuels. Biomethane which is produced by upgrading of biogas is regarded as a good alternative energy and usage of clean energy is encouraged to deal with air pollution and waste management as well as production of clean energy. Recently, biogas projects for vehicle fuel are newly being launched and Korea government have also announced a plan for investment to develop biogas as a transport fuel. In this study, it is aimed to examine the potential feasibility of biomethane as a transport fuel. As a results, the status of biomethane, quality standard, quality characteristics, and upgrading technology of biogas were investigated to evaluate of biogas as a vehicle fuel of transportation.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3335-3340
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• 2007

The government have been tightening EM regulation gradually but the effect is not good because of rapid increase of vehicles. And medium & heavy duty diesel vehicles, even though the number is small, exhaust very large pollutants(about over 50%). Especially it is more severe about old trucks and buses. Accordingly, CNG vehicle and the retrofit of diesel to CNG must be an alternative in order to protect the atmospheric environment and improve the air quality in the metropolitan area. The main object of this study is to secure the retrofit technology of diesel to CNG vehicle and the management system of CNG engine. we passed the government emission certification test. In addition to this, the mass production for retrofit is also studied. Results of emission and durability test for certification are as follows; there was no problem during 30,000km vehicle durability test and good emission levels satisfying the regulation.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.174.1-174.1
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• 2011

Biogas production and utilisation is an emerging alternative energy technology. Biogas is produced from the biological breakdown of organic matter through anaerobic digestion. Biogas can be utilized for various energy services such as heating, electricity generation and vehicle fuel. Especially, to be utilized as vehicle fuel, raw biogas needs to be upgraded, that is, mainly the removal of carbon dioxide to increase the methane content, up to more than 95% in some cases, similar to the composition of fossil-based natural gas. Biogas fuelled vehicles can reduce $CO_2$ emission by between 75% and 200% compared with fossil fuels. Biomethane development is largely driven by national initiative and predominately by concerns for national air pollution and waste management. Recently, biogas projects for vehicle fuels by some companies are ongoing and Korea government also announced investment to develop biogas as a transport fuel. Therefore, the aim of this study is to examine the feasibility of biomethane as a transport fuel in Korea. In this study, we investigated quality characteristics, quality standard and upgrading technology to use vehicle fuel of transport sector in Korea.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.3
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• pp.201-209
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• 2016

Supercavitation is a technology that reduces frictional resistance of an underwater vehicle by surrounding it with bubbles. Supercavity is divided into natural supercavity and ventilated supercavity which is formed by artificially supplying gas. Planing forces are present when a section of the underwater vehicle goes outside of the cavitation region in the supercavity condition. Planing often leads to an unstable flight because it acts vertically on the body suddenly. In this paper, a relationship between the ventilation rate and the cavitation number is determined. Based on the relationship, desired cavitation number which can avoid to planing is determined and then ventilation controller is designed. The performance of the ventilation controller is verified with a depth change controller using the cavitator. Simulation results show that the ventilation controller can minimize the planing force and moment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.10
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• pp.855-862
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• 2017

Due to the weight reduction and miniaturization of satellites, there is a growing interest in low-cost launch vehicles, which are cheaper to launch than larger launch vehicles. One of the most cost-effective ways to reduce the cost of launch vehicles is the reuse of vehicles. Most companies that are developing low cost launch vehicles are also adopting a vehicles reuse approach. Along with this reuse purpose, the demand for environmentally friendly space launch vehicles has increased, so the choice of fuel used for low cost launch vehicles has also become very important. Methane and hydrogen-enriched compressed natural gas (HCNG), which makes more energy-efficient by adding hydrogen to methane, are considered to be the most suitable when considering other factors such as energy density among the fuels that are eco-friendly and capable of reusing the launch vehicles. This study investigated the trends of low-cost launch vehicle and rocket fuel in the world as a reference for setting up domestic space development after the development of Korea Space Launch Vehicle-II.

• Elastomers and Composites
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• v.55 no.4
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• pp.257-262
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• 2020

Vehicle wiper blades are typically treated with chlorine to lower their friction coefficient with the windshield surface. In this study, a chlorinated, natural rubber (NR) vehicle wiper blade was characterized using a pyrolytic technique. Unchlorinated and chlorinated wiper blades were pyrolyzed and the pyrolysis products were analyzed using gas chromatography/mass spectrometry (GC/MS). Besides isoprene and dipentene, the other principal pyrolysis products such as 1,5,8-p-menthatriene (MTT) and p,α-dimethylstyrene (DMS) were observed. The MTT and DMS ratios did not vary for the chlorinated nor unchlorinated samples when the entire rubber lip of the wiper blade was pyrolyzed. However, when only the lip surface of the wiper blade rubber was pyrolyzed (via scratching with a knife) the relative ratios of the chlorinated sample were much greater than those of the unchlorinated sample. As MTT is produced from the conjugated backbone of chlorinated NR that forms through HCl elimination during initial pyrolysis, and DMS is generated by the dehydrogenation of MTT, these two products could be used as markers for detecting chlorinated NR.