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In recent years, the automotive industry has been making efforts to develop vehicles that satisfy customers’ emotions rather than malfunctions by improving the durability of vehicles. The durability and reliability of vehicles sold in the U.S. can be determined through the VDS (Vehicle Dependability Study) published by JD Power. The VDS is index which is the number of complaints per 100 units released by J.D. POWER in every year. It investigates customers who have used it for 3 years after purchasing a new car and consists of 177 specific problems grouped into 8 categories such as PT, ACEN, FCD, Exterior. The VDS-4 has been strengthened since the introduction of the new evaluation system VDS-5 in 2015. In order to improve the VDS index, it is important to gather various customer complaints such as internet data, warranty data, Enprecis data and clarify the problem and cause. Enprecis data is survey of customer complaints by on-line in terms of VDS.

A need to develop a cooling method with high cooling performance like jet impingement is increased as high power of an inverter is required. Jet Impingement on the dimpled plate would increase thermal performance than that of flat plate. Many previous researchers have dealt with the multi jet impingement on flat plate and some results of the study on dimpled plate evaluate the effect on heat transfer coefficients on several limited cases, making it difficult to apply them to inverter designs. Therefore, in this paper, heat transfer performance, pressure drop, and robustness at micro-scale of jet impingement on the dimpled plate were investigated in detail and the correlations of each performance were proposed. Finally, the optimal design was presented. The cooling performance was influenced by the jet array and the effect of depth and width of the dimples.

Lithium-ion battery has advantages of high energy density and cost effectiveness than other types of batteries. However due to the low mechanical stability, their performance is strongly influenced by environmental conditions. Especially, external pressure on a cell surface is a crucial factor because an appropriate force can improve battery cycle life, but excessive force may cause structural failure. In addition, battery pack is composed of various components so that uncertainties in dimension and material properties of each component can cause a wide variance in initial pressure. Therefore, it is important to optimize structural design of battery pack to ensure initial pressure in an effective range. In this paper, target stiffness of module structure was determined based on cell level cycle life test, then structural design has been optimized for weight reduction. Cell cycling tests were performed under different stiffness conditions and analyzed with regression model.

The body stiffness plays a key role in vehicle performance, such as noise and vibration, ride and handling, durability and so on. In particular, a body D-pillar ring structure is the most sensitive affecting the body stiffness on vehicle with tail gate. Therefore, since D-pillar body ring structure for high stiffness and lightweight is required, an optimized design methodology that simultaneously satisfies the requirements was studied. It focused on a methodology that body engineering designers can optimize design parameters easily and quickly by themselves in the preceding stages of vehicle’s styling distribution and design conceptual planning. First, it is important to establish the body stiffness design strategy by predicting the body stiffness with the vehicle’s styling at early design stage. The methodology to predict body stiffness with the styling and body dimension specification parameters was introduced.

Dashcam, which is considered essential parts of vehicles in Korea, are installed in most vehicles for proofs of accidents or threatened driving of other vehicles, and insurance premiums. Also global market is growing continuously. Aftermarket dashcams have been developed with many improvements such as higher resolution camera and a LCD, however still have technical limitations in usability and durability. The First limitation is that the dashcam which mounted on windshield can be separated and injure at an accident due to a collision impact, and the device obstructs the driver's vision. In addition, the connection of the power supply may cause a vehicle damages such as a fire due to a worker's mistake or a product defect. Secondly, in order to replay the recorded video, it is not easy to remove the SD card and check it on the computer. Moreover, since the LCD is so small, it is difficult to search and replay the wanted video from the list in many files.

This paper presents the research related to the self-driving system that has been actively carried out recently. Previous studies have been limited to ensure the path following performance in linear and steady state-alike handling region with small lateral acceleration. However, in the high speed driving, the vehicle cornering response is extended to nonlinear region where tire grips are saturated. This requires a technology to create the driving path for minimum time maneuvering while grasping the tire grip limits of the vehicle in real time. The entire controller consists of three stages-hierarchy: The target motion is determined in the supervisor phase, and the target force to follow the target behavior is calculated in the upper stage controller. Finally, the lower stage controller calculates the actuator phase control input corresponding to the target force.

Body-in-white plays a key role in protecting passengers in the event of collision between vehicles, and also endures external forces during cornering in a vehicle. Stiffness of body-in-white is the basic characteristic of a car body, and it is closely related to the full-vehicle-level performance such as body durability, ride and handling, etc. There have been many attempts to correlate body stiffness to full-vehicle-level performance, and studying the relationship between torsional body stiffness and durability has been the popular topic among others. In general, it is believed to be true that bodies with high torsional stiffness exhibit good durability performance, and in many cases this assumption seems to be verified. However, not all cases are true to this assumption. In this paper, relationship between torsional body stiffness and body durability has been closely studied.

To meet the indoor air quality guideline of newly manufactured vehicles in Korea, China, and other countries, low formaldehyde grade POM (Polyoxymethylene) is used for interior parts essentially. In this paper, formaldehyde scavengers from of 2 commercial low formaldehyde grade POM pellets were identified by LC-MS (Liquid chromatograph-Mass spectrometer) as sebacic dihydrazide and dodecanedioic dihydrazide respectively. The reaction products between formaldehyde and formaldehyde scavengers were also detected, which were converted from hydrazide to hydrazone. So, this kind of additive would be gradually consumed by repetitive molding process or exposure to heat according to formaldehyde emission increase. We are expecting to apply this analytical method and result for quality control and benchmark of low formaldehyde grade POM.

Recently, the design of automotive headlamps has become diversified and complicated according to customer needs. Hence, structural complexity of the headlamps has also increased. Complex structure of the headlamps inevitably causes a disturbance in air circulation. For this reason, inadvertent micro-sized water droplets, called fogging, are condensed on the inner surface of headlamp lens due to temperature difference between the inner and outer lens surfaces. To circumvent fogging inside of the headlamp lens, an anti-fogging coating is indispensable. Conventionally, diverse surfactants have been adopted as substantial material for the anti-fogging coating. However, the usage of the surfactants causes undesirable side effect such as water mark arising from vapor condensation, which is an important issue that must be fully resolved. In this study, we developed an innovative anti-fogging coating material without using conventional surfactant.

48V mild hybrid engine is one of major eco-friendly technology for global CO2 reduction policy. The 48V mild hybrid engine enables to operate torque boost, recuperation and ISG status by MHSG(Mild Hybrid Starter and Generator). The FEAD(Front End Auxiliary Drive) system is a very important role to transfer MHSG power to crankshaft at the mild hybrid engine. The conventional FEAD configuration is relatively simple because it transfers power from crankshaft to auxiliary drive components in one direction. But the FEAD configuration of 48V mild hybrid engine is not simple due to bidirectional power transmission between crankshaft and MHSG. For instance, in case of torque boost mode, the tight side of auxiliary belt is entry span of MHSG. On the contrary, the tight side of auxiliary belt is exit span of MHSG at recuperation mode.

Road friction estimation algorithms had been studied for many years because it is very important factor for safety control and fuel efficiency of vehicle. But traditional solutions are hard to adapt in automotive industry because their performance is not sufficient enough and expensive to implement. Therefore, this paper proposes a road friction estimation algorithm based on a trained artificial neural-network which is low cost and robust. The suggested method doesn’t need expensive additional sensors such as optical or lidar sensor, also it shows better performance in real car environment compared to other algorithms based on vehicle dynamics. In this paper, we would describe this algorithm in detail and analyze the test results evaluated in real road conditions.

In case of cooling module rotated by belt, many sources (vehicle’s vibration, belt’s tension and thrust force by rotated fan) are acting on it. Because it is not easy to analyze them individually, there were no rig test modes for pre-validation while developing a new vehicle. In this study, we correlated the strain gauges signal to belt’s tension and fan’s thrust force, and measured acceleration of a vehicle and cooling module by driving a vehicle on the several test roads. In that case of measured acceleration data, we could analyze it by using PDF and construct the representative rig test modes considering vibrational fatigue characteristics by using the FDS. These modes can be utilized while developing a new vehicle without measuring anymore. Also, we could understand each load’s characteristics. It is confirmed that the factors affecting the fatigue were not only the vehicle’s vibration but also the belt’s installation tension.

This paper presents the direct liquid-cooled power module with the circular pin fin which is the inverter parallel cooling system for high output EV/FCEV. The direct cooling system of a conventional inverter is designed to supply coolant along the direction in which the heating element such as Si-chip is disposed and discharge coolant to the opposite side. In case of the inverter, the higher the output is, the larger temperature difference between inlet and outlet becomes due to the heat exchange of the heat generation element, so that temperature difference depends on the position of Si-chip. Since lifetime is judged on the basis of maximum temperature of Si-chip, the inverter itself must be replaced or discarded due to durability of the inverter even though Si-chip can drive further. The simple way to solve this problem is to increase cooling flow rate, but this leads to excessive increase in pressure loss due to circular pin fin.

Hyundai's new engine is developed which optimize the cooling efficiency for knocking improvement and friction reduction. The cooling concepts for this purpose are 1) equalizing the temperature among cylinders by flow optimization, 2) cooling the required area intensively, 3) adopting ‘active flow control’ and 4) enlarging fuel economy at high speed range. In order to realize the cooling concept, 1) cross-flow, 2) compact water jacket & exhaust cooling, 3) flow control valve and 4) cylinder head with integrated exhaust manifold are considered. Improvement of knocking and friction reduction by increased cooling water temperature makes fuel efficiency possible. On the other hand, in order to strengthen the cooling around the combustion chamber and to reduce the deviation among the combustion chamber of cylinders, it is required to design the head water jacket shape accordingly.

The tire is the vital element in vehicle dynamics, as its contact patch transmits all forces and moments to the ground (accelerating, braking, cornering, rolling).Over the recent decades tire development for passenger cars has been continuously improved and optimized in order to achieve a good overall vehicle performance in R&H that is in balance with all other tire performances (Wear, Durability, NVH, RR, Miles). This general development process has to be suitable for various vehicle types from regular passenger cars over eco-friendly hybrid or electric vehicles to high performance sport cars. The balance between Ride and Handling performance is further adjusted to local customer preferences that are usually distinguished by markets (US, EU, Asia). The tire development process, which is embedded in the overall vehicle development, is usually realized in a mutual collaboration between OEM and tire supplier.

The performance and marketability of eco-friendly vehicles highly depend on their high-voltage battery system. Lithium-ion pouch cells have advantages of high energy density and cost-effectiveness than other types of batteries. However, due to their low mechanical stability, their characteristics are strongly influenced by external conditions. Especially, external pressure on pouch cell is a crucial factor for the performance, life cycle, and structural safety of battery pack. Therefore, optimizing pressure level has been a critical consideration in designing battery pack structures for lithium-ion pouch cell. In this work, we developed an optimized structure of the battery module and pack to apply appropriate pressure on pouch cells. They also include a standardization strategy to meet the varied demand in capacity and power for automotive application.

Recently, upon customer’s needs for noise-free brake, carmakers are increasingly widely installing damping kits in their braking systems. However, an installation of the damping kits may excessively increase softness in the brake system, by loosening stroke feeling of a brake pedal and increasing compressibility after durability. To find a solution to alleviate this problem, we first conducted experiments to measure compressibility of shims by varying parameters such as adhesive shims (e.g., bonding spec., steel and rubber thickness), piston’s shapes (e.g., different contact areas to the shims), and the numbers of durability. Next, we installed a brake feeling measurement system extended from a brake pedal to caliper. We then compared experimental parameters with brake feeling in a vehicle. Finally, we obtained an optimized level of brake feeling by utilizing the Design for Six Sigma (DFSS).

Charge boosting strategy plays an essential role in improving the power density of diesel engines while meeting stringent emissions regulations. In downsized two-stage turbocharged engines, turbocharger matching is critical to achieve desired boost pressure while maintaining sufficiently fast transient response. A numerical simulation model is developed to evaluate the effect of two-stage turbocharger configurations on the perceived vehicle acceleration. The simulation model developed in GT-SUITE consists of engine, drivetrain, and vehicle dynamics sub-models. A model-based turbocharger control logic is developed in MATLAB using an analytical compressor model and a mean-value engine model. The components of the two-stage turbocharging system evaluated in this study include a variable geometry turbine in the high-pressure stage, a compressor bypass valve in the low-pressure stage and an electrically assisted turbocharger in the low-pressure stage.

This study provides a tire puncture sealant including NR latex and acrylic emersion, which has a reduced viscosity at -40°C, and is also excellent storage stability at -40°C to 70°C, initial sealing performance. Also, this study provides device for sealing inflatable objects. 'One- Piece Tire Repair Kit' can reduce weight and operation steps.

In this research, the influence of tire force and moment (F&M) characteristics on vehicle on-center steering performance was analyzed and then how to improve vehicle on-center performance was studied through controlling tire structure design parameter, tread pattern shape and tread grip characteristics. First, the relationship between vehicle on-center steering performance and tire F&M characteristics was identified by comparing vehicle steering measurements and tire F&M measurements. It was found that key factor of tire related with on-center performance is aligning torque at lower slip angles. As the aligning torque at slip angle 1° increases, on-center feel is improved. Second, the influence of tire design parameters on tire aligning torque was studied through F&M finite element (FE) analysis and measurement. It was found that the aligning torque at lower slip angle increases as stiffness of the tread and sidewall decreases.