• Journal of Korean Society of Transportation
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• v.36 no.1
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• pp.38-50
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• 2018

Emerging automated driving environments will lead to a mixed traffic flow depending on the interaction between automated vehicles (AVs) and manually driven vehicles (MVs) because the market penetration rate (MPR) of AVs will gradually increase over time. Understanding the characteristics of mixed traffic conditions, and developing a method to control both AV and MV maneuverings smoothly is a backbone of the traffic management in the era of automated driving. To facilitate smooth vehicle interactions, the maneuvering of AVs should be properly determined by various traffic and road conditions, which motivates this study. This study investigated whether the aggressiveness of AV maneuvering, defined as automated driving aggressiveness (ADA), affect the performance of mixed traffic flow. VISSIM microscopic simulation experiments were conducted to derive proper ADAs for satisfying both the traffic safety and the operational efficiency. Traffic conflict rates and average travel speeds were used as indicators for the performance of safety and operations. While conducting simulations, level of service(LOS) and market penetration rate(MPR) of AVs were also taken into considerations. Results implies that an effective guideline to manage the ADA under various traffic and road conditions needs to be developed from the perspective of traffic operations to optimize traffic performances.

• Journal of Korean Society of Transportation
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• v.30 no.2
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• pp.67-78
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• 2012

The current traffic regulations in Korea stipulate that traffic should keep to the right according to the Road Traffic Act; thus, customarily, the 'seat-on-the-left' system has been maintained. However, an increased number of 'seat-on-the-right' vehicles are being imported via a variety of routes from foreign countries, especially from Japan. According to the data from July 2004, 1,343 cargo vehicles and 593 passenger vehicles (for diplomats, etc.) were currently being driven on domestic road. As these 'seat-on-the-right' vehicles are not compatible with the domestic transportation system of driving on the right side of the road, there is a high risk of accidents. Experiments show that such system-driver mismatch causes longer operation time for directional signals, higher error frequency in yielding due to additional mental adjustments for 'seat-on-the-right' vehicle drivers. These are, therefore, influential factors which can lead to possible accidents. Furthermore, when the experiments test the visual range during overtaking maneuvers, the visual range of the drivers in the 'seat-on-the-left' vehicle was 2.95 meters as opposed to 1.7 meters for the drivers in the 'seat-on-the-right' vehicle. (In the experiment, the drivers were instructed to look at the paper cup 10 meters away from the back of drivers' seat.) The results demonstrate that it is necessary to have additional safety measures be implemented for the 'seat-on-the-right' vehicles.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.5
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• pp.50-58
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• 2014

The PRT(Personal Rapid Transit) system is highly interested to meet a need for demand-responsive transport service and increasing demands of traffic in Korea recently. And it is being spotlighted as an eco-friendly transportation system. For these reasons, researches on the PRT system are actively undergoing in Korea. In this study, we evaluated the static structural and fatigue strengths based on ASCE-APM standards and ERRI B 12/RP 17 by means of FE simulation. We also evaluate the running stability by multi-body dynamic analyses and the rollover safety by a theoretical static stability factor according to the road modeling scenarios for the PRT system. From the results of this study, we confirmed the durability and running stability of the Korean PRT under development.

• Tunnel and Underground Space
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• v.18 no.6
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• pp.393-407
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• 2008

To protection of fire accident and to minimize danger of spreading the disaster. in railway tunnel, MCT (the Ministry of Construction and Transportation) published "Rules about the Safety Standard of Railroad (2005.10.27)" and "The Detailed Safety Standard of Railroad (2006.9.22)". QRA(Quantitative Risk Analysis) results are applied to establish the fire protection facilities in railway tunnel so that institute the reasonable application about the fire safety facilities However, it is difficult to perform the fire safety design due to lack of the detailed standards about event scenario, fire intensity, incidence rate of accidents etc. Therefore, This paper introduces the practical method about detailed standards of QRA.

• Journal of Advanced Navigation Technology
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• v.20 no.4
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• pp.352-360
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• 2016

In this paper, a novel multiple multicast feed-back scheme for improving multimedia multicast and broadcast system based on IEEE 802.11. The proposed scheme improves multicast PPDU delivery ratio of next generation wireless LAN by utilizing multicast feed-back information. By using the proposed scheme, regardless of its size of multicast group, an AP STA could collect transmission failure information by receiving simultaneous NAK frame. The proposed scheme shows large performance enhancement in broadcast or multicast system of Intelligent Transport System and Passenger Entertainment Service. According to the analysis results, the proposed scheme could enhance wireless LAN multicast and broadcast performance significantly.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.3889-3894
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• 2012

The platform of railroad station for domestic passenger train has been operated at two categories like the platforms if low level(500mm, mainline) and high level(1,135mm, metropolitan subway line). To operate both metropolitan subway line and mainline railroad safely, it is essential to develop the doorstep equipment of railway vehicle regardless of low and high level platforms. On the other hand, the domestic test standard at durability and reliability of doorstep equipment has not been existed until now. This study aims at the development on doorstep equipment of telescopic sliding type for low and high level platforms. Durability analysis with VPD(Virtual Product Development) techniques are performed and the durability standard & qualification life through the rig test during no failure test time is examined in accordance with reliability qualification test.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.4
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• pp.223-230
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• 2011

According to EMEP/EEA Emission Inventory Guidebook, the emissions produced by vehicle in cold start phase should be calculated differently compared to hot start phase. In this study, considering this driving cycle, more appropriate procedures for estimating Environmental Benefits was suggested. Using Tier 3 standard, all links within the impact area were included in estimating emissions. Traffic volume and travel distance were analyzed using EMME/3 software. For application of the procedures in this study, the case study was carried out with real transportation project. As a result, the Environment-Benefits increased by 30%. If the methodology suggested in this study is applied to feasibility study it will help to activate the investment of the environment-friendly modes like railway in the future.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.491-497
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• 2005

Brake system is indispensible functional part to the transportation machines such as railroad cars, and all of industrial machines. It is mechanical element to stop the movement or slow the speed, transforming kinetic energy of motion object into thermal energy through solid friction. According that recently the railroad cars have become high-speed, the technique in braking domain to secure the overall braking effort is making rapid progress. In particular, material development and manufacturing process are so important to secure friction performance, which is the core in braking performance of mechanical brake units. Wear of brake disk could mainly result in the diminishment of its life span due to thermal cracking, so the endurance against high temperature is required. On the other hand, in this case, the problem is that the side wear of pad, relative material is slightly increased because of enlargement of plastic deformation. It is necessary, therefore, to develop a disk material that will be used in the Tilting System mechanical brake units. The purpose of this paper is to make a study prior to developing brake disk of Tilting Train travelling at 200km/h and to propose the component of brake disk. Accordingly, I will conduct sufficient researches on technical documents of brake disk, that are basic documentations, analyze an impact on components, and further, considering braking degree of train, study for the basic proposal on brake disk's component of the train travelling at 200km/h, which has relatively minor influence of heat stress and maintains the friction. In this respect, I would like to investigate friction characteristics between disk and relative friction material via Test on some possible test segments, analyze and propose friction performance, temperature impact and so forth coming from the contact with pad, relative material to demonstrate the friction characteristics.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1964-1969
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• 2010

Recently, as construction market scale is getting bigger and transportation industry is developing, the underground structure construction such as subway, tunnel (excavation box) or shield tunnel structure is becoming more diverse, and its demand is gradually increasing. However, for the concrete structures constructed underground, the water leakage is occurred due to the expansion joint and construction joint, or movement, uneven settlement, excessive load and vibration during application causing cracks. Many waterproofing method and materials are used in jobsites, but areas such as underground railroad and subway that has movement and vibration at all times, the ability of waterproofing layer is declined causing repetitive water leakage due to crack, erosion and separation, which is a vicious cycle. Therefore, this study evaluates the responsiveness to a movement for adhesive/flexible waterproofing material that can cope with the vibration and the movement of the structure. Also to recommend a waterproofing technology that can cope with structure movement through examples of actual jobsite applications such as subway and tunnel where there are constant movement and vibration.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.6
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• pp.723-730
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• 2013

The speed-limit regulation on a turnout is the main factor inhibiting the speed-up of conventional lines. The specified speed for a train moving through a turnout system is lower than that for a train traveling over the general track. This is done to ensure the running safety of a railway vehicle moving through a turnout. In this study, the shape change example of the guard rail component of a turnout in the Daegu Metropolitan Transit Corporation (DTRO) system was studied. A theoretical examination of the geometrical interaction formula according to wheel/rail shape at the turnout was conducted. Running safety analysis by changing the length of the guard rail on the F10/F12 turnout using the developed analysis techniques (by VI-Rail) was achieved, and the effect on railway safety was examined accordingly.