• Journal of Institute of Control, Robotics and Systems
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• v.22 no.8
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• pp.633-642
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• 2016

It is important for advanced active safety systems and autonomous driving cars to get the accurate estimates of the nearby vehicles in order to increase their safety and performance. This paper proposes a sensor fusion method for radar and vision sensors to accurately estimate the state of the preceding vehicles. In particular, we performed a study on compensating for the lateral state error on automotive radar sensors by using a vision sensor. The proposed method is based on the Interactive Multiple Model(IMM) algorithm, which stochastically integrates the multiple Kalman Filters with the multiple models depending on lateral-compensation mode and radar-single sensor mode. In addition, a Probabilistic Data Association Filter(PDAF) is utilized as a data association method to improve the reliability of the estimates under a cluttered radar environment. A two-step correction method is used in the Kalman filter, which efficiently associates both the radar and vision measurements into single state estimates. Finally, the proposed method is validated through off-line simulations using measurements obtained from a field test in an actual road environment.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.3
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• pp.383-391
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• 2006

In Korea, the major source of serious air pollution is motor vehicles. Air pollution from vehicles has been annually increased. Then the government will try to control the vehicle emission by applying the effective emission management policy for the manufactured and in-used car. It is necessary to correctly calculate the emission factor for successful propulsion of the vehicle emission control policy. In this study, correlation analysis of exhaust emissions from vehicles between CVS-75 mode and Korea mode was conducted. A total of 25 light-duty buses were tested on the chassis dynamometer system in order to measure CO, HC, NOx PM and fuel efficiency (F.E.). For the test modes, 10 different Korea modes and CVS-75 mode were used. As the result of correlation analysis between those modes, most of the correlation coefficients were higher than 0.90. On the basis of high correlation between those modes, correction factors by driving conditions were estimated. Through the results of this study, we obtained essential basic data to correct difference from those modes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.193-198
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• 2004

In order to keep the market competitiveness, it is desirable for automotive manufacturer to meet the customer's various aspects of requirements. The overall NVH (Noise, Vibration, and Harshness) performance has been an important measure when evaluating overall vehicle performance, product quality, and enhancing customers' loyalty to the product. The noise and vibration, while the engine is idling, has been brought particular attention to the drivers and passengers, because they encounter the operation conditions quite frequently without other masking noise sources: wind noise, road noise, and even powertrain radiated noise at higher speed driving. The specific noise, defined as 'CHIT' noise, has been identified as a potential customer issue, from the Pickup Truck with newly developed V8 powertrain. This paper describes the definition of the noise, identifying the potential sources, and noise radiation mechanisms, based on series of powertrain and vehicle test and verification processes. Then, based on the root-cause identified, the design change has been proposed and validated with several vehicles in order to have a complete satisfaction of the customer.

• Journal of Auto-vehicle Safety Association
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• v.14 no.3
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• pp.60-64
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• 2022

In the automotive industry, the development of automobiles to meet safety requirements is becoming increasingly complex. This is because quality evaluation agencies in each country are continually strengthening new safety standards for vehicles. Among these various requirements, collision safety must be satisfied by controlling airbags, seat belts, etc., and can be defined as post-crash safety. Apart from this safety system, the Advanced Driver Assistance Systems (ADAS) use advanced detection sensors, GPS, communication, and video equipment to detect the hazard and notify driver before the collision. However, research to improve passenger safety in case of an accident by using the sensor of active safety represented by ADAS in the existing passive safety is limited to the level that utilizes the sudden braking level of the FCA (Forward Collision-avoidance Assist) system. Therefore, this study aims to develop logic that can improve passenger protection in case of an accident by using ADAS information and driving information secured before a collision. The proposed logic was constructed based on LSTM deep learning techniques and trained using crash test data.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.3
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• pp.153-159
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• 2007

Nano-Particles are influenced on the environmental protection and human health. The relationships between transient vehicle operation and nano-particle emissions are not well-known, especially for diesel passenger vehicles with DPF. In this study, a diesel passenger vehicle was measured on condition of DPF regeneration and no regeneration on a chassis dynamometer test bench. The particulate matter (PM) emission from this vehicle was measured by its number, size and mass measurement. The mass of the total PM was evaluated with the standard gravimetric measurement method while the total number and size concentrations were measured on a NEDC driving cycle using Condensation Particle Counter (CPC) and EEPS. Total number concentration by CPC was $1.5{\times}10^{1l}N/km$, which was 20% of result by EEPS. This means about 80% of total particle emission is consist of volatile and small-sized particles(<22nm). During regeneration, particle emission was $6.2{\times}10^{12}N/km$, was emitted 400 times compared with the emission before regeneration. As for the particle size of $22{\sim}100nm$ was emitted mainly, showing peak value of near 40nm in size. This means regeneration decreased the mean size of particles. Regarding regeneration, PM showed no change while the particle number showed about 6 times difference between before and after regeneration. It seems that the regeneration influences on particle number emissions are related to DPF-fill state and filtration efficiency.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.10
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• pp.2195-2202
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• 2011

Recently, navigation system is used to inform users of vehicle location and driving direction, moving distance and so on. This navigation uses GPS sensor for current location determination. The GPS sensor will determinate current coordinates by using triangulation algorithm. This characteristic bring about that the GPS signal is not available in the shadow region such as tunnel and urban canyon. Moreover, Even though the signal is available, inherent positional error rate of the GPS often results in the dislocation of vehicle. To solve, these problems, a new positioning system is proposed in the paper. The System utilizes geomagnetic sensors of smartphone, speed information of CAN of vehicle though bluetooth and WiFi APs for GPS shadow area. The experimental test shadows that the proposed system using multiple data is able to determine the position of vehicle in GPS shadow areas.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.1
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• pp.26-32
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• 2022

This paper proposes a power system that includes a 120k W fuel cell DC-DC converter (FDC) and 30 kW bidirectional DC-DC converter (BHDC) for a 150 kW fuel-cell vehicle. With a high DC link voltage of 800 V, the efficiency and power density of the power electronic components are improved. Through the modular design of FDC and BHDC, electric components are shared, resulting in reduced mass production costs. The switching frequency of 30 kHz of full SiC devices and optimal design of coupled inductor reduce the volume, achieving a power density of 8.3 kW/L. Furthermore, a synergetic operation strategy using variable limiter control of FDC and BHDC was proposed to efficiently operate the fuel cell vehicle considering the fuel cell stack efficiency according to the load. Finally, the performance of the prototype was verified by Highway Fuel Economy Driving Schedule testing, EMI test, and the linked operation between FDC and BHDC. The full load efficiencies of the FDC and BHDC prototypes are 98.47% and 98.74%, respectively.

• Journal of Sensor Science and Technology
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• v.31 no.6
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• pp.411-417
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• 2022

In this paper, we propose a sensor with a C-shaped load cell to detect force change when a person sitting on the chair in an electrical transport-convenience vehicle is pushing ground by both heels. The load cell built in the vehicle is mechanically deformed by the vertical force owing to the human weight and the horizontal force by ground-pushing feet. The deformation rate of the load cell and its distribution are simulated using finite element analysis. In the simulation, the applied loads are preset in the range of 10 kg - 100 kg with a step size of 10 kg, and the ground-pushing force by feet is increased to 40 N with a step size of 5 N with respect to each applied load level. The resistance change of the load cell was observed to be linear in simulation as well as in measurement. the maximum difference between simulation and measurement was 0.89 % when the strain gauge constant was 2.243. The constant has a large influence on the difference. The proposed sensor was fabricated by connecting an instrument amplifier and a microcontroller to a load cell and used to detect the force by ground-pushing feet. To detect foot driving, the reference signal was set to 130% of the load, and the duration of the sensor output signal exceeding the reference signal was set to 0.6 s. In a test of a vehicle built with the proposed sensor, the footpushing force by the worker could be successfully detected even when the worker was working.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.432-439
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• 2020

Brake judder has been identified in some operating military units of Korean Light Tactical Vehicles(KLTV) with In-board brake systems to improve braking performance. Severe vibration generated while driving the vehicle may reduce the KLTV's driving stability and further lead to accidents. For the prevention of this, this study analyzes the root cause through the failure analysis on the vehicles with the brake judder identified. Furthermore, the improvement factor was derived by identifying a vibration transmission path by analyzing the vibration transmission mechanism. The study analysis confirmed that the vibration of the frame during braking in the tactical vehicle is a cold judder phenomenon, which is caused by an increase in disk thickness variation due to rust and foreign substances under excessive brake disc's run-out. In addition, it was confirmed that such vibration can be reduced by improving the mounting structure. So, an improvement method for each factor was suggested and its effectiveness was verified by comparison test. Finally, it is expected that the improvement plans derived through this study can be used in the development of a next military vehicle.

• 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.