• Proceedings of the KSR Conference
• /
• 2008.06a
• /
• pp.1968-1977
• /
• 2008

A bimodal low-floor tram is designed to provide the flexibility of bus and the punctuality of trains together to the passengers. Its propulsion system is a series hybrid type using a set of CNG engine generator and Li-polymer battery. The present paper describes the specifications of the propulsion system in the bimodal tram which was drawn by a desirable driving cycle. In addition, it shows how the propulsion system of the bimodal tram can be controlled. With using a computer simulation tool of hybrid vehicles, ADVISOR, the performance of the bimodal tram was verified.

• Proceedings of the KSR Conference
• /
• 2009.05a
• /
• pp.930-939
• /
• 2009

A bimodal tram is being developed to combine the flexibility of a bus with the punctuality of a train. The propulsion system is a series hybrid type using a set of CNG engine generator and Li-polymer battery. This paper presents the experimental results of the series hybrid propulsion power unit using an active loader which can simulate powering and regenerative braking conditions of the propulsion equipments continuously. The power sharing scheme between PWM converter and a battery pack has been observed. The measurement results of DC link voltage and SOC(State Of Charge) of battery pack are presented.

• Journal of Energy Engineering
• /
• v.19 no.3
• /
• pp.171-176
• /
• 2010

Using a hydrogen blended compressed natural gas (HCNG) as a fuel for IC engines has a significant meaning in terms of achieving a reduction of automotive exhaust emissions as well as preparing for an upcoming hydrogen economy by constructing hydrogen infrastructure. In addition, a HCNG engine has higher thermal efficiency than a CNG engine, which is another advantage that makes HCNG fuel considered as a future alternative for natural gas. Therefore, in this study, idling operation of a 11 litre HCNG bus engine was investigated in terms of fuel consumption rate and emissions characteristics. The results show that fuel consumption rate was decreased more than 20% by use of HCNG and all the emissions were significantly reduced in idling condition.

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

• Journal of Korean Society of Transportation
• /
• v.32 no.2
• /
• pp.93-105
• /
• 2014

This study evaluated the relative efficiency of mobile emission reduction countermeasures through a Data Envelopment Analysis (DEA) approach and determined the priority of countermeasures based on the efficiency. Ten countermeasures currently applied for reducing greenhouse gases and air pollution materials were selected to make a scenario for evaluation. The reduction volumes of four air pollution materials(CO, HC, NOX, PM) and three greenhouse gases($CO_2$, $CH_4$, $N_2O$) for the year 2027, which is the last target year, were calculated by utilizing both a travel demand forecasting model and variable composite emission factors with respect to future travel patterns. To estimate the relative effectiveness of reduction countermeasures, this study performed a super-efficiency analysis among the Data Envelopment Analysis models. It was found that expanding the participation in self car-free day program was the most superior reduction measurement with 1.879 efficiency points, followed by expansion of exclusive bus lanes and promotion of CNG hybrid bus diffusion. The results of this study do not represent the absolute data for prioritizing reduction countermeasures for mobile greenhouse gases and air pollution materials. However, in terms of presenting the direction for establishing reduction countermeasures, this study may contribute to policy selection for mobile emission reduction measures and the establishment of systematic mid- and long-term reduction measures.

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

• Journal of Korean Society for Atmospheric Environment
• /
• v.29 no.4
• /
• pp.477-485
• /
• 2013

The major source of harmful air pollutants in Korea have been shifted as economy grows. Particulate matter(PM) and Sulfur dioxide ($SO_2$) emitted from industries and coal-fired domestic sectors were important pollutants in 1970's and later industrializing period of Korea. Then the characteristic of pollution was changed into so-called "developed country type pollution". Vehicles have been responsible for significant amount of Nitric oxide ($NO_x$) pollution and consequent Ozone formation in urban area since 1990's. Variety of control measures have been introduced to deal with the vehicle emissions in Seoul Metropolitan Area (SMA). Emission control technologies have successfully reduced pollutants from vehicles. Three-way catalyst for vehicles fueled by gasoline and liquefied petroleum gas (LPG), for example, has achieved large amount of pollutants. Compressed natural gas (CNG) urban bus have penetrated existing diesel bus market and reduces PM and $NO_x$ emissions in many Korean cities. However, diesel vehicles are still reaming as a critical emission source of urban area. Diesel vehicles gain more popularity than ever because of their better fuel efficiency and driving power. Unfortunately, it is widely known that the pollutant emissions of diesel vehicles are much larger than those of gasoline and LPG vehicles. In this note, we briefly introduce the trends of emission control strategies which are accomplished by automotive industries for about last ten years. Emission regulation, cleaner fuel, diesel particulate filter (DPF) and other measures are discussed from technical as well as legislative perspectives.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.19 no.1
• /
• pp.71-82
• /
• 2020

The existing transportation system, which is based on internal combustion engines, is rapidly being converted to electrification. Thus, eco-friendly public transportation with high transportation efficiency will continue to spread throughout the market in the near future. The purpose of this study is to compare and analyze the cognitive characteristics of passengers redgarding the technical and social factors of various public transportation means to help a successful introduction of eco-friendly public transit. Through a survey questionnaire (N=485), seven factors of seven transportation modes were evaluated and analyzed using principal component analysis. As a result, it is confirmed that potential passengers have high expectations for the eco-friendliness and city image of the eco-friendly buses. Also, it is confirmed that eco-friendly buses are superior in cleanliness and ride comfort than diesel buses. Given the study's results, this study identifies the cognitive characteristics of passengers regarding eco-friendly public transportation. We hope that these results will be used as basic information for image positioning and improved service with the use of eco-friendly transportation.

• Journal of Korean Society of Transportation
• /
• v.26 no.3
• /
• pp.145-153
• /
• 2008

This study proposes a facility location model in consideration of spatial coverage and travel cost as an effort to make objective and effective decisions of natural gas filling stations. The proposed model is developed for fixed stations and consists of two stages. The first stage employs a heuristic algorithm to find a set of locations which satisfy the spatial coverage constraints determined by the maximum travel distance between the filling stations and bus depots. In the second stage, the optimal location of filling stations is determined based on the minimum travel cost estimated by using a modified transportation problem as well as the construction and maintenance costs of the filling stations. The applicability of the model is analyzed through finding the optimal location of filling stations for the city of Anyang, a typical medium-sized city in metropolitan Seoul, based on the demand of natural gas buses. This study is expected to help promote the spread of natural gas buses by providing a starting point of a objective and reasonable methodological perspective to address the filling station location problem.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.22 no.4
• /
• pp.686-692
• /
• 2013

Today, environmental issues have become a matter of worldwide concern. In particular, automobile industries engage in considerable research and investment to develop high-efficiency and ecofriendly cars. Most ecofriendly cars use natural gas or hydrogen gas instead of fossil fuels. In this regard, low-weight and high-pressure vessels have gradually been developed to increase the driving distance of a car. However, most pressure vessels installed in cars develop many defects over time owing to shocks sustained when the car is being driven. Such defects can cause the explosion of the pressure vessel. Therefore it is important to prevent such explosions due to internal defects. The use of shearography for measuring the internal defects of objects afford many advantages. It is a non-contact and non-destructive method, and it is not limited by the object shape. In this study, the internal defect deformation and strain of an aluminum liner that is used in a CNG bus for the fuel storage tank is measured using shearography. It is important to measure the strain and deformation in order to detect defects and repair the pressure vessel. To verify the accuracy of the shearography measurement method, the measurement results of shearography, out-of-plane ESPI, and FEM are compared quantitatively.