• Transactions of the Korean Society of Automotive Engineers
• /
• v.10 no.5
• /
• pp.168-173
• /
• 2002

The durability test, along with the crashworthiness test, requires the most time and expense in the vehicle development process. The durability design using CAE tools reduces the time required for both the durability test and actual vehicle production. Existing dynamic stress analyses designed fir the analysis of vehicle fatigue mainly calculate the dynamic stress history and fatigue after performing dynamic analysis and stress analysis with relevant software applications and then superpositioning the dynamic load history and stress influence coefficient at each joint. This approach is a complex process, taking into account the flexibility of the parts. It is, however, incapable of giving accurate consideration to the contacts between components, the non-linearity of materials, and tire-road surface interactions. This approach also requires that the analysts have an expertise in software applications of various kinds or an expert in each area must perform the analysis. This requires as a great deal of manpower and time. In order to complement the existing approaches for dynamic stress analysis, this study aims at the following: (1) to suggest the simple and accurate analysis technique which is capable of producing all the possible necessary results; (2) to reduce dramatically the time and manpower needed to construct a model designed to analyze dynamics, quasi-static stress, and fatigue; and (3) to enable an accurate analysis of fatigue by improving the accuracy of dynamic stress. we verify the presented analysis method through durability evaluation of the knuckle of passenger car.

• IE interfaces
• /
• v.24 no.1
• /
• pp.78-86
• /
• 2011

To mitigate space restriction and to raise productivity, some shipbuilding companies use floating-docks on the sea instead of dry-docks on the land. In that case, a floating-crane that can lift very heavy objects (up to 3,600 tons) is used to handle the blocks which are the basic units in shipbuilding processes, and so, very large blocks (these are called the mega-blocks) can be used to build a ship. But, because these mega-blocks can be made only in the area near the floating-dock and beside the sea, the space is very important resource for the process. Therefore, our problem is to make an efficient spatial schedule for the mega-block assembly yard. First of all, we formulate this situation into a mathematical model and find optimal solution for a small problem using a commercial optimization software. But, the software could not give optimal solutions for practical sized problems in a reasonable time, and so we propose a GA-based heuristic algorithm. Through a numerical experiment, finally, we show that the spatial scheduling algorithm can provide a very good performance.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.18 no.3
• /
• pp.133-139
• /
• 2023

This paper proposes a two-stage Water Shield Automation System (WSAS) to predict the possibility of river overflow and vehicle flooding due to sudden rainfall. The WSAS uses a two-stage Deep Neural Network (DNN) model. First, a river overflow prediction module is designed with LSTM to decide whether the river is flooded by predicting the river's water level rise. Second, a vehicle flooding prediction module predicts flooding of underground parking lots by detecting flooded tires with YOLOv5 from CCTV images. Finally, the WSAS automatically installs the water barrier whenever the river overflow and vehicle flooding events happen in the underground parking lots. The only constraint to implementing is that collecting training data for flooded vehicle tires is challenging. This paper exploits the Image C&S data augmentation technique to synthesize flooded tire images. Experimental results validate the superiority of WSAS by showing that the river overflow prediction module can reduce RMSE by three times compared with the previous method, and the vehicle flooding detection module can increase mAP by 20% compared with the naive detection method, respectively.

• International Journal of Advanced Culture Technology
• /
• v.11 no.2
• /
• pp.330-344
• /
• 2023

This research report cuts across management sciences (market strategy entry mode development) and innovative technology (Electric Vehicle (EV)) alongside measures to submerge global warming. The development of a successful entry mode for the electric Vehicle into the African continent is the main objective of the study. The study focuses on an analysis of how electric car manufacturers can enter the African market in other to achieve global sustainability and social responsibility. The methodology is based on identifying the factors that affect the choice of an entry mode into international markets by multinational companies desiring to leverage their revenue through a foreign market. It also offered a quantitative approach that can support the economic and sustainability entry mode model for EVs and a qualitative approach of Porter's five forces analysis as an entry mode coaching tool for EVs. These proxies are used in quite a wide range of multivariate statistical methods (trend analysis, ratio, and probability, comparative t-test technique, auto-regression, and ordinary least square technique). The result acknowledges joint venture and setting of the plant (physical presents) as the optimal entry mode in African EV market. It requires the EV manufacturers a tire-free emission innovation technology in order to optimize the global sustainability initiative.

• International Journal of Highway Engineering
• /
• v.17 no.6
• /
• pp.11-18
• /
• 2015

PURPOSES : The purpose of this thesis is to evaluate the effectiveness of an active noise cancellation (ANC) system in reducing the traffic noise level against frequencies from the predictive model developed by previous research. The predictive model is based on ISO 9613-2 standards using the Noble close proximity (NCPX) method and the pass-by method. This means that the use of these standards is a powerful tool for analyzing the traffic noise level because of the strengths of these methods. Traffic noise analysis was performed based on digital signal processing (DSP) for detecting traffic noise with the pass-by method at the test site. METHODS : There are several analysis methods, which are generally divided into three different types, available to evaluate traffic noise predictive models. The first method uses the classification standard of 12 vehicle types. The second method is based on a standard of four vehicle types. The third method is founded on 5 types of vehicles, which are different from the types used by the second method. This means that the second method not only consolidates 12 vehicle types into only four types, but also that the results of the noise analysis of the total traffic volume are reflected in a comparison analysis of the three types of methods. The constant percent bandwidth (CPB) analysis was used to identify the properties of different frequencies in the frequency analysis. A-weighting was applied to the DSP and to the transformation process from analog to digital signal. The root mean squared error (RMSE) was applied to compare and evaluate the predictive model results of the three analysis methods. RESULTS : The result derived from the third method, based on the classification standard of 5 vehicle types, shows the smallest values of RMSE and max and min error. However, it does not have the reduction properties of a predictive model. To evaluate the predictive model of an ANC system, a reduction analysis of the total sound pressure level (TSPL), dB(A), was conducted. As a result, the analysis based on the third method has the smallest value of RMSE and max error. The effect of traffic noise reduction was the greatest value of the types of analysis in this research. CONCLUSIONS : From the results of the error analysis, the application method for categorizing vehicle types related to the 12-vehicle classification based on previous research is appropriate to the ANC system. However, the performance of a predictive model on an ANC system is up to a value of traffic noise reduction. By the same token, the most appropriate method that influences the maximum reduction effect is found in the third method of traffic analysis. This method has a value of traffic noise reduction of 31.28 dB(A). In conclusion, research for detecting the friction noise between a tire and the road surface for the 12 vehicle types needs to be conducted to authentically demonstrate an ANC system in the Republic of Korea.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2004.05a
• /
• pp.408-413
• /
• 2004

High speed planning boats also have been required more and more the rational strength analysis and evaluation for the optimal structural design in respect of the structural lightness according to the high speed trend. Even though the suggestion of the simple type equation for the equivalent dynamic pressure is reasonable to design the scantling of ship structure conveniently, many research activities for more reasonable improvement of the simple design pressure, have been continued to suggest the more accurate equivalent static description of tire structural response such as the deflection and stress of hull structure. In this research, we focus on the aluminum bottom stiffened plate structure in which structural scantling is mainly depend on the local loads such as dynamic or impact pressure without other load effects and structural response for the simple dynamic equivalent pressure was investigated through the structural analysis. In order to investigate the structural response of the bottom stiffened plate structure subjected to the dynamic equivalent design pressure, linear and nonlinear structural analysis of the bottom stiffened plate structure of 4.3 ton aluminum planning boat was performed based on the equivalent static applied loads which were derived from the KR regulation and representative one among various dynamic equivalent pressure equations. From above analysis results, we found that the response such as deflection and stress of plate member was similar with the response results of one plate member model with fixed boundary, which was published previous paper and in case of KR design loading, all response of stiffened plate structure were within elastic limit. Through the nonlinear analysis, nearly elastic behavior including the slight geometrical nonlinear response was dominant but plastic local zone was appeared at $85\%$ limit load. Therefore, we can say that through tire linear and nonlinear analysis, this stiffened plate member has no structural strength problem based on the yield criteria in case within $60\%$ limit load except the other strength point of view such as the fatigue and buckling problem.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.4D
• /
• pp.491-497
• /
• 2009

This paper presents the results of accelerated pavement tests (APT) that simulate permanent deformation (rutting) of asphalt concrete pavements under different temperatures and loading courses. Also, finite element (FE) analysis has been conducted to predict the test results. Test section for APT is the same as one of test sections at Korea Expressway Corporation test road and is subjected to a constant moving dual tire wheel load of APT at three different temperatures: 30, 40, $50^{\circ}C$. The moving wheel is applied at different loading courses within a 75cm wide wheel path to account for traffic wandering. Also, the effect of wandering on permanent deformation development is investigated numerically with three wandering schemes. In this study, ABAQUS is adopted to model APT pavement section with plain stain elements and creep strain rate model is used to take into account viscoplastic stain of asphalt concrete mixtures, and elastic layer properties are back-calculated from FWD measurements. Plus, the effect of boundary condition and subgrade on FE permanent deformation predictions is investigated. A full FE model that accounted for subgrade provided more realistic rut depth predictions, indicating subgrade has contributed to surface rutting.

• Journal of Institute of Control, Robotics and Systems
• /
• v.19 no.1
• /
• pp.45-55
• /
• 2013

With the recent advancement of control method and battery technology, the electric vehicle have been researched to replace the conventional vehicle with electric vehicle with the view point of the environmental concerns and energy conservation. An electric vehicle which is equipped with the independent front steering system and in-wheel motors has advantage in terms of control. For example, the different torque which generated by left and right wheels directly can make yaw moment and the independent steering using outer wheel control is able to reduce the sideslip angle. Using of independent steering and driving system, the 4 wheel electric vehicle can improve a performance better than conventional vehicle. In this paper, we consider the method for improving the cornering performance of independent front steering system and in-wheel motor used electric vehicle with the compensated outer wheel angle and direct yaw moment control. Simulation results show that the method can improve the cornering performance of 4 wheel electric vehicle. We also apply the steering motor failure to steer the vehicle turned by the torque difference without steering. This paper describes an independent front steering and driving, consist of three parts; Vehicle Model, Control Algorithm for independent steering and driving and simulation. First, vehicle model is application of TruckSim software for independent front steering and 4 wheel driving. Second, control algorithm describes the reduced sideslip and direct yaw moment method in view of cornering performance. Last is simulation and verification.

• Journal of Environmental Science International
• /
• v.18 no.10
• /
• pp.1103-1114
• /
• 2009

In this study, the environmental behavior of malodor pollutants (MPs: $H_2S$, $CH_3SH$, DMS, and DMDS) was investigated around areas influenced by strong anthropogenic processes based on observations and modeling study (a CALPUFF dispersion model). The MP emission concentrations were measured from 8 industrial source regions (tire plants (S1-S3), waste water disposal plant (S4), and oil refinery (S5) in an urban center area and paper mill/incineration plant (S6) and livestock feedlots (S7-S8) in Ungsang area) in Yangsan city during a fall period in 2008 (21 October 2008). Overall, the most MPs emitted from the urban center area were found to affect the malodor pollution in their downwind areas during early morning (06:00 LST) and nighttime (18:00 and 21:00 LST), compared with those in the Ungsang area. For malodor intensity, the most MPs in the urban center area (especially S1 and S2) were found to be a significant contributor, whereas $CH_3SH$ and $H_2S$ in the Ungsnag area (especially S6) were the dominant contributor. The model study showed agreement in the spatial distributions of simulated MPs with those of the observations. The largest impact of MPs in the urban center area on the malodor pollution in its residential areas occurred at S1, S2, and S3 sites during nighttime, while that of MPs in the Ungsang area occurred at S6 and S8 sites. This may be caused mainly by the high MP emissions and in part by wind conditions (prevailing northeasterly winds with low wind speeds of 2-3 m/s).

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.42 no.12
• /
• pp.997-1003
• /
• 2014

This paper describes modeling process to obtain precise landing gear model which is necessary to design a control law for ground auto-taxi, auto take-off/landing of UAV. In this paper, landing gear side force modeling is studied to complete a landing gear model of UAV. Side force modeling is performed by calculating cornering angle including steering angle. And ground directional controller is designed by using nose wheel steering and rudder steering at the same time to control course angle error. Accuracy of landing gear side force modeling and ground directional controller is proved by comparing of auto-taxi test results with simulation results.