• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.2
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• pp.153-160
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• 2015

Hybrid Electric Vehicles(HEVs) have seriously come into prevalence recently as car manufacturers and consumers have become more aware of the environmental and economic problems of conventional vehicles. For the alternative power-train and battery cooling systems in HEVs, an effective thermal management system is required, and many automakers are interested in using Brushless DC(BLDC) motors for cooling fans for the overall traction unit's performance and energy saving capability. This paper presents the development status of BLDC motors as major parts of the power-train, i.e. the engine cooling and battery cooling fans of HEVs. A design that uses BLDC motors for the power-train and each battery cooling fan, is successfully implemented through using electro-magnetic analysis, and prototype BLDC motors are examined. As experimental results, the BLDC motors achieved an efficiency of 85% as engine cooling fans and 72% as a battery thermal management fan motor. The electric cogging noise is significantly reduced by changing the skew of the slot pitch angle and optimizing the magnetic shape.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.8
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• pp.3567-3588
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• 2018

In the Internet of Things (IoT) concept, devices communicate autonomously with applications in the Internet. A significant aspect of IoT that makes it stand apart from present-day networked devices and applications is a) the very large number of devices, produced by diverse makers and used by an even more diverse group of users; b) the applications residing and functioning in what were very private sanctums of life e.g. the car, home, and the people themselves. Since these diverse devices require high-level security, an operational model for an IoT system is required, which has built-in security. We have proposed the societal model as a simple operational model. The basic concept of the model is borrowed from human society - there will be infants, the weak and the handicapped who need to be protected by guardians. This natural security mechanism works very well for IoT networks which seem to have inherently weak security mechanisms. In this paper, we discuss the requirements of the societal model and examine its feasibility by doing a proof-of-concept implementation.

• 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.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.6 no.1
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• pp.64-69
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• 2006

Due to the inherent nonlinear nature of Electro-rheological (ER) fluid dampers, one of the challenging aspects for utilizing these devices to achieve high system performance is the development of accurate models and control algorithms that can take advantage of their unique characteristics. In this paper, the nonlinear damping force model is made to identify the properties of the ER damper using higher order spectrum. The higher order spectral analysis is used to investigate the nonlinear frequency coupling phenomena with the damping force signal according to the sinusoidal excitation of the damper. Also, this paper presents an inverse model of the ER damper, i.e., the model can predict the required voltage so that the ER damper can produce the desired force for the requirement of vibration control of vehicle suspension systems. The inverse model is constructed by using a multi-layer perceptron neural network. A quarter-car suspension model is considered in this paper for analysis and simulation. Simulation results show that the proposed inverse model of ER damper can obtain control voltage of ER damper for required damping force.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2218-2224
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• 2016

Opportunistic routing is designed for an environment where there is no stable end-to-end routing path between source node and destination node, and messages are forwarded via intermittent contacts between nodes and routed using a store-carry-forward mechanism. In this paper, we consider PRoPHET(Probabilistic Routing Protocol using History of Encounters and Transitivity) protocol as a base opportunistic routing protocol and propose an efficient context-aware opportunistic routing protocol by using the context information of delivery predictability and node type, e.g., pedestrian, car, and tram. In the proposed protocol, the node types of sending node and receiving node are checked. Then, if either sending node or receiving node is tram, messages are forwarded by comparing the delivery predictability of receiving node with predefined delivery predictability thresholds depending on the combination of sending node and receiving node types. Otherwise, messages are forwarded if the delivery predictability of receiving node is higher than that of sending node, as defined in PRoPHET protocol. Finally, we analyze the performance of the proposed protocol from the aspect of delivery ratio, overhead ratio, and delivery latency. Simulation results show that the proposed protocol has better delivery ratio, overhead ratio, and delivery latency than PRoPHET protocol in most of the considered simulation environments.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.356-361
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• 2005

Earth brush for electrical multiple units(EMUs) is a device through which the current of the EMU load's consumed power fed from the DC 1,500V overhead line (or from the AC 25.000V catenary) flows via axle to the rail(ground) and which prevents the electric corrosion of the axle bearings by preventing the current flow to the axle bearings caused by electric potential from the magnetic field when the bearings rotate together with the earthing function when a thunderbolt falls or a surge comes. The earth brush wear rates among cars, however, shows quite differences when the earth brushes after being separated from the holders are measured with vernier callipers every 6 months of maintenance period. Main causes of the earth brush wear are divided as mechanical, electric arc and electrical one, and the factors can be running speed, current, harmonics, connection state. spring tension, earth brush material, lubricant and so on. but only the earth brushes of the motor(M1) car show the highest wear rate and moreover maintenance difficulty occurs because of the wear rate differences among e earth brushes in one holder. The reason for these preponderant wear comes from the design concept of making preponderant current flow to some particular earth brushes and moreover the heat generated by the harmonics when the inverter starts to operate accelerate the wear. By defining these causes through experiments. I hope that the found results would be helpful for the future EMU design, safety, economy and maintenance.

• Journal of Auto-vehicle Safety Association
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• v.12 no.1
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• pp.26-32
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• 2020

The luxury car market has been steadily growing for the last 10 years and it might keep expanding in the future. Furthermore, it is expected to be a very competitive market because luxury cars are considred to reflect the technology level of motor companies. For this reason, it is very important for motor companies to improve performances of luxury vehicles. However, it takes years for the companies to increase the technology level for the high performances. In this paper, we aim to analyze the technologies for high quality brake perfomances through investigation of two luxury vehicle models and develop a new high performance brake system. First, we found out a variety of effective factors for the high performances. Second, we conducted the brake performance analysis to figure out the relationship between brake effort and brake feeling. Finally, we develped the new brake system using carbon ceramic composite materials to satisfy the high quality brake performances.

• International Journal of Automotive Technology
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• v.7 no.1
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• pp.51-59
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• 2006

The high potential for injury involved in rollover accidents warrants the development of a system to protect passengers against such events. To effectively implement such a protection system, it is first necessary to determine rollover criteria (i.e., real time states which indicate the occurrence of rollover events). In this paper, several rollover criteria have been developed based on simplified physical models. Such accidents are first classified into two types, untripped and tripped, according to the main cause that initiates the rollover. Characteristics of these rollover situations are identified by applying appropriate principles of dynamics to corresponding simplified physical models. Two main rollover criteria, Rotational Kinetic Energy (RKE) and Initial Kinetic Energy (IKE), are then introduced based on these characteristics. ADAMS/View simulations have been performed to verify the feasibility of the introduced rollover criteria. ADAMS/Car simulations have also been conducted to get more realistic rollover data with a complete vehicle model. Results of these experiments reveal that our established criteria prove useful for predicting whether actual rollover occurs or not.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.6
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• pp.29-37
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• 1994

Active noise control of random noise which propatate in the vehicle cabin as a form of spherical wave is the target of this study. In the previous study, the adaptive algorithm for adaptive controller is presented for the application in active noise control system. And for the preliminary study of adaptive active noise control in vehicle cabin as a real system, a computer simulation is performed on the effectiveness of the adaptive algorithm in the amplitude of the pressure fluctuation. This work studies the implementation of multi-channel feedforward adaptive algorithm for the reduction of the noise inside a vehicle cabin using a number of secondary sources derived by adaptive filtering of reference noise source. Multi-channel adaptive feedforward algorithm are verified in numerical simulation and semi-experimental justification of developed system is made on a domestic passenger car. In the results of semi-experimental study, the noise of specific region in the interior of automobile are reduced for the appreciabe sound pressure level in the operating engine rpm and finally this study suggests the capabilities of the real time active noise control in 3 dimensional acoustic fields.

• Journal of Information Technology Services
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• v.14 no.4
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• pp.269-281
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• 2015

The objective of this study is offering new on line business model for automotive market. In order for the research aim, we conduct direct in-depth interviews with CEO, including analysis of business patterns on eight automotive firms in Gwangju city. As a result, we suggest new business model so called, Online to offline (o2o) that combines advantages in both off-line and on-line business. Techniques that o2o automotive companies may employ include in-store pick up of items purchased online, allowing customers. Purchasing the automotive is not only a car but also services including insurance, warrant services. o2o business model suggested shows the operating of the goods and service sale. When it comes to characteristics of automotive conventional sale patterns, utilization of the online-to-offline commerce has not eliminated the advantages that e-commerce companies have. That model can enhance the new values for customers as well as new market creation. Also, this new business model (o2o) can contribute the emerging industry business model installed based in particular, emergence of Iot (Internet of thing) in terms of sharing knowledge and information between enterprise and customers.