• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.9
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• pp.817-823
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• 2017

In the past, research has been conducted on the development of an adaptive cruise control algorithm considering fuel efficiency, and an adaptive cruise control system considering fuel efficiency have been developed. However, research on optimizing vehicle and adaptive cruise control parameters in order to maximize performances is insufficient. In this study, the design optimization of vehicle and control parameters considering fuel efficiency, trackability, ride comfort and safe distance is performed. This paper proposes performance measures of vehicle behavior and develops an adaptive cruise control system. In addition, based on the screening of vehicle parameters that significantly influence performances, kriging surrogate models are constructed through a sequential design of experiment, and kriging surrogate model-based design optimization is performed to maximize fuel efficiency and satisfy target performances.

• IEMEK Journal of Embedded Systems and Applications
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• v.15 no.5
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• pp.215-225
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• 2020

Light detection and ranging (LiDAR) sensors detect the distance of the surrounding environment and objects. Conventional LiDAR sensors require a certain amount of a power because they detect objects by transmitting lasers at a regular interval depending on a constant resolution. The constant power consumption from operating multiple LiDAR sensors is detrimental to autonomous and electric vehicles using battery power. In this paper, we propose two algorithms that improve the inefficient power consumption during the constant operation of LiDAR sensors. LiDAR sensors with algorithms efficiently reduce the power consumption in two ways: (a) controlling the resolution to vary the laser transmission period (T_P) of a laser diode (LD) depending on the vehicle's speed and (b) reducing the static power consumption using a sleep mode depending on the surrounding environment. A proposed LiDAR sensor with a resolution control algorithm reduces the power consumption of the LD by 6.92% to 32.43% depending on the vehicle's speed, compared to the maximum number of laser transmissions (N_x·max). The sleep mode with a surrounding environment-sensing algorithm reduces the power consumption by 61.09%. The proposed LiDAR sensor has a risk factor for 4-cycles that does not detect objects in the sleep mode, but we consider it to be negligible because it immediately switches to an active mode when a change in surrounding conditions occurs. The proposed LiDAR sensor was tested on a commercial processor chip with the algorithm controlling the resolution according to the vehicle's speed and the surrounding environment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.3
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• pp.379-385
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• 2013

The tires, suspension type, and steering system can all cause pulling during braking. Among these, a drag link steering system and leaf-type suspension system are significant causes of vehicle pulling. In this study, the pulling problem is analyzed using the vehicle analysis program "ADAMS/CAR." The drag link and leaf spring behavior is analyzed to find the key reason for pulling. After this, the optimization program "Visual DOC" is used with "ADAMS/CAR" to find a steering link connection point to reduce pulling. After conducting this simulation, K&C (kinematic & compliance) test simulation with a modified connection point is conducted to determine whether the vehicle performance improves. Through a full braking simulation, it is verified that the pulling distance is reduced at braking.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.4
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• pp.31-39
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• 2010

Although driving patterns strongly influence greenhouse gas and air pollutant emission rate from light duty vehicles, emission measurements have been mainly based on chassis dynamometer testing with one standard driving pattern. And there has been limited work on quantifying the independent effect of driving parameters on emission rate because of multidimensional nature of real-world driving pattern. The objective of this study is to obtain the quantitative effect of relative positive acceleration (RPA) on vehicle emission rate. RPA has been used to define the occurrence of acceleration demanding large amounts of power in certain driving distance and shown to be a significant affecting parameter for real-world emission rate. 40 driving patterns have been developed with fixed driving parameters to investigate independent effect of RPA. For the same values of average vehicle speed and power, the trend in carbon dioxide emission rate and fuel consumption with respect to RPA is very clear. Emission rate of nitrogen oxide and particulate matter also increase with respect to RPA, but the trend is less clear. Carbon dioxide emission from diesel vehicle appear to be more affected by high accelerations compared to that from gasoline vehicle because of high intake air restriction during acceleration caused by turbocharger and intercooler. The results have implications for the possible reduction of environmental effects through better traffic planning and management, driver education and car design.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.3
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• pp.53-60
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• 2020

Evaluating the operational efficiency of electric vehicle charging stations (EVCSs) is important to understand charging network evolution and the charging behavior of electric vehicle users. However, aggregation of efficiency performance metrics poses a significant challenge to practitioners and researchers. In general, the operational efficiency of EVCSs can be measured as a complicated function of various factors with multiple criteria. Such a complex aspect of managing EVCSs becomes one of the challenging issues to measure their operational efficiency. Considering the difficulty in the efficiency measurement, this paper suggests a way to measure the operational efficiency of EVCSs based on data envelopment analysis (DEA). The DEA model is formulated as constant returns of output-oriented model with five types of inputs, four of them are the numbers of floating population and nearby charging stations, distance of nearby charging stations and traffic volume as desirable inputs and the other is the traffic speed in congestion as undesirable one. Meanwhile, the output is given by the charging frequency of EVCSs in a day. Using real-world data obtained from reliable sources, we suggest operational efficiencies of EVCSs in Seoul and discuss implications on the development of electric vehicle charging network. The result of efficiency measurement shows that most of EVCSs in Seoul are inefficient, while some districts (Nowon-gu, Dongdaemun-gu, Dongjak-gu, Songpa-gu, Guro-gu) have relatively more efficient EVCSs than the others.

• The Journal of Information Systems
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• v.29 no.2
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• pp.131-147
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• 2020

Purpose The purpose of this study is to develop intelligent vehicle parking distribution system based on LoRa network at the circumstance of traffic congestion during cultural festival in a local city. This paper proposes a parking dispatch and distribution system using a Q-learning algorithm to rapidly disperse traffics that increases suddenly because of in-bound traffics from the outside of a city in the real-time base as well as to increase parking probability in a parking lot which is widely located in a city. Design/methodology/approach The system get information on realtime-base from the sensor network of IoT (LoRa network). It will contribute to solve the sudden increase in traffic and parking bottlenecks during local cultural festival. We applied the simulation system with Queuing model to the Yudeung Festival in Jinju, Korea. We proposed a Q-learning algorithm that could change the learning policy by setting the acceptability value of each parking lot as a threshold from the Jinju highway IC (Interchange) to the 7 parking lots. LoRa Network platform supports to browse parking resource information to each vehicle in realtime. The system updates Q-table periodically using Q-learning algorithm as soon as get information from parking lots. The Queuing Theory with Poisson arrival distribution is used to get probability distribution function. The Dijkstra algorithm is used to find the shortest distance. Findings This paper suggest a simulation test to verify the efficiency of Q-learning algorithm at the circumstance of high traffic jam in a city during local festival. As a result of the simulation, the proposed algorithm performed well even when each parking lot was somewhat saturated. When an intelligent learning system such as an O-learning algorithm is applied, it is possible to more effectively distribute the vehicle to a lot with a high parking probability when the vehicle inflow from the outside rapidly increases at a specific time, such as a local city cultural festival.

• Journal of the Korea Furniture Society
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• v.23 no.4
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• pp.467-478
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• 2012

Interurban railway is expanded by transportation that population can be centralism and cope efficiently in traffic jam by augmentation of vehicles in the city. Railroad chair departs in space of an existent simple rest and products that can raise human body standard and size by powerful engineering vicinity, quality of the material, psychological satisfaction etc. of users are developed steadily. Specially, study of space that can use various materials efficiently with bodily size government official because various of man and woman old and the young etc.. are using in occasion of the train is urgently required. Specially, railroad chair is a product that material and standard, structure, human body engineering, a finish etc. is studied variously. In the case of advanced nation, in case of design a chair operating time of railroad, is placed as all standards orderly and harmonious because is considered exercise dynamics etc.. and designs. The other side, in the case of our country, study expert of chair is short real and is depending on technological data of overseas railway vehicle. Chair for railroad must consider removal of short-range, long distance. That have to be consider to a lot of uncomfortable such as psychological satisfaction of user because the domestic Motor Companies are defining in fair development study and many researchers but the railroad chair company are not accumulated professional manpower and technological know-how. Railway vehicle can recognize that overseas visitors as well as native is important element as space that space is exposed internationally by product that Public personality which used cultural value is strong. Therefore, wish to plan valid spec relationship presentation of various design and specification, function etc.. and contribute to railroad chair development design process lists and analyzes van instances of railway vehicle chair of inside and outside of the country through this study.

• Journal of the Korean Society of Safety
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• v.24 no.4
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• pp.28-33
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• 2009

This study examined the mounting status of cigar lighter receptacles for vehicles and analyzed the tracking phenomenon that occurs when foreign material entered a cigar lighter receptacle to obtain data for the analysis of accident investigation. Regardless of the vehicle's output, cigar lighter receptacles are mounted in a vehicle horizontally, vertically, or at tilting or inclined angle. The tilting type cigar lighter receptacle is much easier to use but current leakage resulting from foreign materials (coffee, beverages, water, etc.) falling into the cigar lighter receptacle may cause a fire to start. This study used a vehicle battery (DC 12V) as a power supply for the tracking test and configured its circuit in the same way as that of an electrical device in a vehicle. The tracking phenomenon that occurred in the standby mode of the vehicle exhibited a fine flame and an irregular occurrence of smoke. While this tracking phenomenon was occurring, the leakage current and the reaching distance of the flame were measured to be approximately 930mA and $20{\sim}50cm$, respectively. It is thought that the resultant flame may ignite toluene, dust, cigarettes, etc. It was observed that as the tracking progressed, the internal metal socket melted and a hole was created, the surface of which was also severely carbonized. In addition, the electrical resistance of the carbonized conductive path was measured to be approximately $30{\Omega}$. It is thought that this much resistance may cause local heating when leakage current flows and could ignite any nearby flammable material.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.4
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• pp.12-17
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• 2018

A natural cavitation-type high-speed underwater vehicle with solid rocket motor is tested, and its speed and running distance are measured. The outputs from pressure sensors on the surface of the vehicle reveal a pressure-time history reflecting the development of supercavitation. Underwater cameras installed on the wall of the test pool record the entire process from the onset of supercavitation to its full development. CNU-SuperCT, based on two-dimensional inviscid theoretical analysis, is used to simulate test results. Considering CNU-SuperCT does not include the control fins of the vehicle, simulation results agree with test results very well. Additionally, pictures from underwater cameras support the test results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.7
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• pp.962-970
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• 2021

The cause of the majority of vehicle accidents is a safety issue due to the driver's inattention, such as drowsy driving. A forward collision warning system (FCWS) can significantly reduce the number and severity of accidents by detecting the risk of collision with vehicles in front and providing an advanced warning signal to the driver. This paper describes a low power embedded system based FCWS for safety. The algorithm computes time to collision (TTC) through detection, tracking, distance calculation for the vehicle ahead and current vehicle speed information with a single camera. Additionally, in order to operate in real time even in a low-performance embedded system, an optimization technique in the program with high and low levels will be introduced. The system has been tested through the driving video of the vehicle in the embedded system. As a result of using the optimization technique, the execution time was about 170 times faster than that when using the previous non-optimized process.