Development of a valve and optimization of a tube for self-inflating tire

Worldwide, the tire market requires safe and eco-friendly tires. In this study, a self-inflating tire (SIT) was studied and manufactured. Self-inflating tire refers to a technique for maintaining appropriate tire pressure. An internal regulator senses when tire inflation pressure has dropped below the set air pressure. The tire boosts air through the valve when rolling and compressed air enters into the tire. This procedure keeps the tire air pressure at an appropriate level and increases tire safety. In this study, a regulator was used as a negative-pressure system. A check valve was selected the minute flow check valve depending on the shape of the configured system. In addition, the material of the tube was developed with excellent physical properties and resistances (elastic rebound, working temperature, etc.) owing to its complete compression and restoration. A tube performance tester was developed and a computer aided engineering (CAE) model was modeled for comparison with the test results. Using the tester and model, it was possible to optimize the shape of the tube and regulator. Finally, the reliability of the study was verified through the prototype test. The developed equipment and systems can be used for the manufacture of high-performance and safe tires.     

Objective evaluation of the sound quality of the warning sound of electric vehicles with a consideration of the masking effect: Annoyance and detectability

This study developed a method to evaluate the sound quality of the warning sound masked by background noise considering the masking effect. The warning sound of an electric vehicle is required by law for the safety of pedestrians. Therefore, the warning sound becomes an additional noise pollution source if it is designed as an annoyance. On the other hand, if the sound is designed with a low sound pressure level, pedestrians will not recognize the approach of vehicle due to background noise. To avoid nose pollution and permit the detectability of an approaching vehicle, a method for evaluating the annoyance and detectability of an electric vehicle is required. In this paper, the whine index evaluating the whine sound masked by the background was developed and used as a sound metric. This metric was employed for the development of an annoyance index and detectability index for electric vehicles.     

Impact of electric vehicles on existing car usage: A mixed multiple discrete–continuous extreme value model approach

This study investigates how the introduction of electric vehicles may influence the usage of existing cars. A survey of 250 households in South Korea is used to analyze a future automobile market that includes electric vehicles taking into account the heterogeneity of consumer preferences and usage patterns. Based on consumer preferences, the future market share of various vehicles is estimated and the impact of promoting the usage of electric vehicles by government subsidization and tax incentives is analyzed.     

Assessment of an engine cylinder head-block joint using finite element analysis

An engine cylinder head-block joint is a gasketed, bolted joint. Assessment of sealing performance and fatigue durability of the joint during engine development relies entirely on the engine dynamometer test because the rig test cannot mimic the engine run condition and finite element analysis employs gasket and bolt models that are too simple to provide the stress data for fatigue assessment. This paper introduces finite element-based assessment of the gasket and the bolt and a model that improves the analysis accuracy without increasing computation time. Experimental data for the deformation of joint members under thermo-mehanical load are presented to demonstrate the accuracy of the model.     

Special provisions for left turns at signalized intersections to increase capacity and safety

Heavy left-turns at intersections are not only difficult to accommodate but also often cause traffic accidents. Such problem can be reduced by adopting an exclusive left-turn signal phase, but in this case the cycle length needs to be extended and the overall intersection capacity reduced. This problem is particularly important in such countries as Korea where unprotected left turns are rarely used. Innovative intersection designs and operational methods for avoiding these problems are presented and their effects of increasing capacity and reducing vehicle delay are analyzed. They rule out the requirement for exclusive left-turn phase while accommodating a large volume of left-turns quite safely.     

Development of a hydraulic limited slip differential system using a pressure generator

The limited slip differential (LSD) is a device that enables the driving force to be transmitted from one slipping wheel to the other by temporarily restraining the differential function when unwanted slipping occurs on muddy or icy roads. Many types of LSD have been developed, such as mechanical lock, disk clutch, viscous coupling, torsen and multiple clutch. This study designed a new type of hydraulic LSD using a pressure generator base on a trochoid gear pump and evaluated the performance of the new design.