• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.1
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• pp.186-192
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• 2007

In general, pulsation damper is installed in fuel rail for conventional MPI engine to decrease undesirable noise in vehicle cabin room. However, pulsation damper is so expensive that there are prevailing studies to reduce fuel pressure pulsations with integrated damping effect. This paper is one of basic studies for development of fuel rail to abate pulsations with self-damping effect. Primarily, the pressure pulsation characteristics was investigated with aspect ratio of cross section, wall thickness, and materials of fuel rail. A high aspect ratio or thin wall was found to absorb the pressure pulsations effectively. But volume effects on the fuel pressure pulsation reductions were not especially significant than cross section effects because volume increment rate is larger than pressure pulsation reduction rate. The fuel rail made of aluminum is effective for reduction of pressure pulsation than that of low-carbon steel. Pressure change period increases on the basis of same lengths of supply line and fuel rail as the volume is enlarged and/or the thickness of wall is thinned.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.4
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• pp.444-453
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• 2015

In the previous study, several problems were observed in a NG conversion vehicle, which were fail of air-fuel ratio closed loop control, aggravated fuel economy, increased harmful emission and declined roadability. It was provisionally supposed that the mismatch of injection system with the engine caused these performance deterioration. In this context, the characteristics of fuel injection system of commercial conversion kit for NG were investigated experimentally varying the engine speed, fuel rail pressure and volume. The results are as follows; The injection quantity decreases as the engine speed increases due to the extremely small rail volume of the presenting system and flow rate of No. 2 injector are always lower than that of the other ones regardless of the speed under the dynamic operation condition. Furthermore the existing system does not meet the required fuel quantity for the normal engine operation over 3000 RPM. On the other hands, the large rail volume systems ease and/or eliminate the difference of injection quantity between the injectors according to the speed variation, however, these systems decrease injection flow rate and still cannot supply sufficient fuel. Finally, suitable combination of the higher rail pressure and the larger rail volume might be a solution about these problems.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1409-1415
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• 2010

A linear induction motor have advantages for reducing mechanical frictions and noises because it has thrust force by induced torque instead of friction force between rail and wheels. An it has additional advantage for reducing volume of bogie frame for light rail transit. The small volume causes the cost of construction down. Recently, researches of linear induction motor for thrust force of the light rail transit have been actively studied. For the rail transit, vehicle is running as follow accelerating and constant speed, finally decelerating speed passing local stops between stations. The light rail transit have only these three patterns of operating. Thus, design of that has different design specifications from others. In this paper, the linear induction motor for the light rail transit was designed considering the goal speed, accelerating time, and accelerating distance for approaching the goal speed. The designed motor was proved that it could meet the requirement of accelerating performance by2-dimensional finite element method and mechanical dynamics equation.

• Journal of the Korean Society for Railway
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• v.11 no.6
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• pp.550-561
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• 2008

The purpose of this paper is to propose a new transit assignment model for intercity rail networks. The characteristics of intercity rail are different from that of public transit in urban area. Line selection probability on route section is introduced to include the characteristics of intercity rail into transit assignment model. Network expansion is more simplified by a assumption line selection probability is externally given. The generalized cost is used to decide the volume of each transit line in most of existing transit assignment models. But, many variables have influence on the volume of each line such as time schedule of transit lines, inter-station distance, passengers' income, seasonal variation of demand and regional characteristics. The influence of these variables can be considered to decide the volume of each line by introducing line selection probability on route section. The tests on a small scale network show that the model proposed in this paper is superior to existing models for predicting intercity rail demand. Proposed model is suitable to consider the complicated fare structure of intercity rail and to draw inter-station demand directly as a result of assignment procedure.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.283-289
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• 2004

Rail defects(Corrugation, shelling, etc) are occurred by the Rail with wheel contact stress. Rail grinding is maintaining of optimal rail profile to use special rail grinding machine to remove rail defect. The benefits of rail grinding enforcement, improve track safety, improve track steering and rail life, improve ride comfort and reduce noise, etc. Actually when rail grinding plan apply to field track, we should consider a lot of function before determination, such as grinding method, grinding pass number, removing metal volume, etc. because each track has various characteristics. Therefore it is important that the determination of rail grinding strategy for optimum and economic before enforcement.

• Journal of the Korean Society for Railway
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• v.9 no.4 s.35
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• pp.441-448
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• 2006

Following the recent privatization of the UK railway system there has been an increase in the volume of rail freight. It. Influential factors include the problem of road congestion, and policies towards increasing grants. With a focus on grants (government subsidies), this paper examines changes in rail freight, and the tasks facing the UK railway. I attempt to explain recent trends in rail freight grants and changes that have positively influenced the rail freight. In particular, I demonstrate the trends in rail freight and scheme which link the government and industry. Moreover, I explain the grants scheme and method of calculation, concisely. Finally I reveal the characteristics of UK rail grants scheme. In this paper, I argue that grants have played an important role of in the development of freight and that rail freight is more environment friendly than road transport. This paper have a many important aspects. Namely, an account of the introduction of the grant scheme of UK. Also, I explore the method of calculation of these grants. It will give some lessons for Korea rail. In conclusion, I note some suggestions and those problems which impede the freight transport. In future, the problems of some of these problems should be addressed, For example, the lack of infrastructure and development of an adequate train time schedule in case of rail freight have to be improved.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.2297-2302
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• 2010

The status and effectiveness of Bi-modal Tram is analyzed through the comparison of the transport effectiveness and operation cost between the public transportation systems (bus, light rail transit) considering the vehicle and operation characteristic of new transit system Bi-modal Tram. The standard operation schedule is established in consideration of the vehicle specification and operation characteristic of main public transportation modes, and then the annual average operation cost is estimated depending on the volume, speed, analysis length for respective public transportation mode. Through analyzing the operation cost and distribution characteristic of public transportation modes depending on the transport volume and travel speed, the operational efficiency suitable for the city is derived. It is concluded that the operational efficiency of Bi-modal Tram is superior to that of the bus and light rail transit on the aspect of travel volume and operation speed.

• Journal of ILASS-Korea
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• v.15 no.1
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• pp.8-16
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• 2010

This paper present the diesel spray characteristics at different injection system parameters in a HSDI diesel engine. The spray characteristics was calculated by the coupled simulation of fuel injection system model and three-dimensional KIVA-3V code with TAB spray model. The relevant injection parameters are accumulator volume, control chamber initial volume, control orifice diameter, needle valve diameter and nozzle chamber initial volume, etc. Parametric investigation with respect to twelve relevant injection parameters showed that there was a significant advantage in varying control chamber initial volume, control chamber orifice diameter, and nozzle chamber orifice diameter with respect to effect the SMD and fuel injection speed. Consequently, in order to design the fuel injection system for spray characteristics, it seems reasonable to suppose to be optimized the fuel injection system.

• Proceedings of the KSR Conference
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• 2001.05a
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• pp.88-96
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• 2001

Rail crossings are major accident-prone areas. Higher traffic volume, frequent rail operation, increased train speed all contribute to increased accident rate and severity In Korea efforts are being made to upgrade currently at-grade rail crossings to grade crossings. There is, however, no quantified analysis measures to analyse the impact of rail grade crossing, thus make it difficult to prioritize different projects under the budget constraints. Projects are selected based on the negotiation between Korea National Railway(KNR) and local governments. To shed light on the development effort for Korean procedure, GradeDec 2000 program of Federal Railroad Adminstration(FRA) was applied for Korean context. Case study involving three rail crossing was ca]lied out, and results are analyzed. Research efforts which need further attention are identified, research direction is analyzed considering local procedure, and issues in the application of the procedures are discussed in detail.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.465-471
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• 2011

In order to make an feasibility analysis of such as rail and road transportation infrastructure, it is common to perform economic analysis. one of the most important thing is how to estimate the operation cost of freight rail because that is required during the analysis time period and sometimes that takes more cost than the construction cost. Therefore, this study is to perform the verification of freight rail operation cost which is applied to the economic analysis of railway investment analysis. for this, it is compared truck operation cost variation with freight rail operation cost, when freight volume is converted from road to railway. In conclusion the cost variation of railway part is bigger than road part so it is necessary to improve the operation cost of freight rail estimation process.