• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.431-437
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• 2017

In this study, based on the RPS algorithm, the application results to an electrically controlled suspension system using previewed road information are presented. Reducing the excessive vibration induced by a disturbance transmitted to the system and secure its stability is a major issue. In particular, in the automotive industry, the demand is constantly being raised. A typical external disturbance causing vibration and instability of a vehicle is an irregular roadway surface that contacts a running vehicle tire. Therefore, obtaining such profile information is an important process. The RPS algorithm using a multi sensor system was constructed and implemented in a real car. Through experimental work using the RPS system included non-contact type optical sensors, it could robustly reconstruct the road input profiles from the intermixed data onto the vehicle's dynamic motion while traveling at an uneven roadway surface. A controller with a preview control was designed in the framework of a semi-active suspension system based on the 7 degrees of freedom full vehicle model. The control performance of the system was evaluated through simulations and the results were compared with the passive vehicle condition. These results highlight the feasibility of the presented control frame.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.10 no.2
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• pp.133-139
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• 2016

An electric wheelchair is a assistive device to maneuver on the ground. Tip-over of an electric wheelchair is increasing every year. Dynamic stability metric test item in KS P 7176 has not ensured safety of electric wheelchair on the slope. This study presents design the foldable electric wheelchair that can load in the car and analysis of tip-over measurement which is easily computed for electric wheelchair. Wheelchair frame is designed with a four-bar link mechanism for a foldable structure, and seat module, battery and power driving module can be separated. This analysis is performed during a maneuver on the ground by force-moment stability metric. Several elements, center of gravity position, rotational radius and acceleration, were evaluated how to affect stability metric. This stability metric can reduce tip-over of wheelchair and provide a clue to make of dynamic stability test item.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.8
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• pp.4068-4076
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• 2013

The wheel-rail interaction forces are influenced by the velocity of vehicle, wheel load, alignment (curve radius, cant etc). For the safety of track structure, it is required to evaluate the influences for track and influential factors. Recently, the HEMU 430-X, which was developed by Next Generation High-Speed Rail Development R&D Project, achieved 421.4km/h in a test run of Daegu.Busan section of the Gyeongbu high speed rail on March in 2013. In the case of additional speed-up test on Test-Bed Section(Gongju.Jeongeup: KP 100~128km Osong starting point), the analysis of track forces is required for outer rail by the increase of dynamic force and centrifugal force of vehicle. In this paper, the vehicle speed variation on HSL line is evaluated by TPS analysis considering the tractive effort of HEMU 430-X, tested running resistance and alignment of Honam HSR. And the track forces are evaluated by centrifugal force and impact factor on curved track.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.2
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• pp.134-139
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• 2021

Currently, the autonomous vehicle market is commercializing a level 3 autonomous vehicle, but it still requires the attention of the driver. After the level 3 autonomous driving, the most notable aspect of level 4 autonomous vehicles is vehicle stability. This is because, unlike Level 3, autonomous vehicles after level 4 must perform autonomous driving, including the driver's carelessness. Therefore, in this paper, we propose the Emergency-notification and Driver-response Confirmation System(EDCS) for an autonomousvehicle safety that notifies the driver of an emergency situation and recognizes the driver's reaction in a situation where the driver is careless. The EDCS uses the emergency situation delivery module to make the emergency situation to text and transmits it to the driver by voice, and the driver response confirmation module recognizes the driver's reaction to the emergency situation and gives the driver permission Decide whether to pass. As a result of the experiment, the HMM of the emergency delivery module learned speech at 25% faster than RNN and 42.86% faster than LSTM. The Tacotron2 of the driver's response confirmation module converted text to speech about 20ms faster than deep voice and 50ms faster than deep mind. Therefore, the emergency notification and driver response confirmation system can efficiently learn the neural network model and check the driver's response in real time.

• Journal of Advanced Navigation Technology
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• v.27 no.1
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• pp.36-42
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• 2023

The development of autonomous vehicles are currently being actively carried out by various companies and research institutes. Expectations for commercialization in daily life as well as specific industries are also rising. Simulators for autonomous vehicles are an essential element in algorithm development and execution considering stability and cost. In this need, various simulators and platforms for simulators are emerging, but research on simulations that reflect various meteorological environmental factors in the real world is still insufficient. This paper proposes a traffic simulation for autonomous vehicles that can consider the weather environment. The weather environment that can be set is largely classified into four categories, and an improved collision prevention algorithm to apply them is presented. Simulation development was conducted through Carla's Python API, a development tool for autonomous driving, and the performance results were compared with existing collision algorithms. Through this, we tried to propose improvements for the development of advanced self-driving vehicle simulations that can reflect various weather environmental factors in real life.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.604-609
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• 2002

In development of an advanced bicycle simulator, the investigation of the interactions between bicycle and rider during cycling is paramount important because bicycle is a two-wheeled human-powered vehicle. Tn this work, the tilt stability. among various interactions, of bicycling is investigated experimentally, In the experiments, the tilt angles of the bicycle, riders body and head are measured, as the riding p;1th and the speed are varied. Subjects are asked to ride along four typical paths on rigid flat ground : the straight, C-curved, S-curved and circle paths. The results from extensive experiments with different subjects can be summarized as : 1) The tilt angles of bicycle and rider are almost out of phase during pedaling along the straight path. 2) The bicycle tilt angle is nearly proportional to the square of bicycle speed for the straight and curved paths, and to the curvature for the curved paths. The head tilt angle is the biggest and the body tilt angle is the smallest for the straight path, but the tendency is reversed for the C-curved path. During the curve maneuvering, the rider's head tends to tilt by less than 40% of the bicycle tilt angle.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.132-137
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• 2011

Many studies are being conducted to improve high speed, light weight and safety of passenger. To improve safety of rolling stock, safety of running performance is most important, and optimizing flow lubrication in driving gear is essential. This study simulates lubricant flow change in driving gear casing which is splashed by the surface of low speed gear teeth following rotational direction of driving gear unit for EMU by using CFD analysis, and based on analysis detail, non-load actual test is conducted for similar driving condition to find out suitability of analysis, selection of lubricate and stability of driving gear.

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.839-844
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• 2002

This research aims to test the running stability of the developed bogie with maximum operating speed of 350km/h, which of Korea TGV was 300km/h. The running stability test has been executed in status of a dummy car with one developed bogie and one dummy bogie on the roller rig to embody similar operation condition. The test has been done in the two rail conditions, i.e. excitation and non-excitation, respectively. Running speed has been increased by the roller step by step. In consequence, the developed bogie was proven to be able to run upto 400 Km/h without any unstable point in the non-excitation. Vibration characteristics of carbody also was within the value specified on the UIC 515.

• Journal of Advanced Navigation Technology
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• v.23 no.6
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• pp.542-547
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• 2019

Autonomous train is investigated to increase the capacity of railroad, and the reliability of wireless communication plays a critical role in terms of decreasing the inter-train distance. In this paper, we propose a transmission scheme for autonomous train communication in highly congested environment. The proposed scheme, namely distributed uplink orthogonal frequency division multiple access (OFDMA) random access (UORA), applies the triggered uplink access (TUA) and the UORA, introduced in the sixth generation WLAN standard, IEEE 802.11ax, for communication devices on vehicle and platform in a distributed manner. The simulation results show that the proposed scheme efficiently improves the packet transmission success rate in highly congested channel conditions compared to the conventional enhanced distributed channel access (EDCA) transmission scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.2
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• pp.133-141
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• 2014

Recently, various services are provided by using WAVE protocol for communication among neighboring vehicles. And in order to operate stable system, the gateway for interconnecting in and out vehicle networks is required. In this paper, we propose gateway interconnecting WAVE and CAN protocol. The proposed gateway based on OSEK OS consists of a communication layer, a message translator layer and a message management layer. In the communication layer, WAVE communication part and CAN communication part are designed to communicate with WAVE and CAN. And in the message management layer, message management layer functions to store the received messages and check errors with the message. Based on these functions, experiment was conducted to analyze performance of the gateway with two scenarios such as transmitting periodically BSM as a message structure for safety services in vehicle-to-vehicle communications and responding to road side equipments requiring in-vehicle information. As a result of test, we verify our gateway performance by analyzing measured time in test scenarios.