• Environmental Engineering Research
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• v.25 no.3
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• pp.366-373
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• 2020

The autonomous vehicles (AVs) could make a positive or negative impact on reducing mobile emissions. This study investigated the changes of mobile emissions that could be caused by large-scale adoption of AVs. The factors of road capacity increase and speed limit increase impacts were simulated using a conceptual modeling approach that combines a hypothetical speed-emission function and a traffic demand model using a virtual transportation network. The simulation results show that road capacity increase impact is significant in decreasing mobile emissions until the market share of AVs is less than 80%. If the road capacity increases by 100%, the mobile emissions will decrease by about 30%. On the other hand, driving speed limit increase impact is significant in increasing mobile emissions, and the environmentally desirable speed limit was found at around 95 km/h. If the speed limit increases to 140 km/h, the mobile emissions will increase by about 25%. This is because some vehicles begin to bypass the congested routes at high speeds as speed limit increases. Based on the simulation results, it is clear that the vehicle platooning technology implemented at reasonable speed limit is one of the AV technologies that are encouraging from the environmental point of view.

• Structural Engineering and Mechanics
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• v.58 no.2
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• pp.199-216
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• 2016

A large number of bridges were built several decades ago, and most of which have gradually suffered serious deteriorations or damage due to the increasing traffic loads, environmental effects, and inadequate maintenance. However, very few studies were conducted to investigate the vibration behaviors of a damaged bridge under moving vehicles. In this paper, the vibration behaviors of such vehicle-bridge system are investigated in details, in which the effects of the concrete cracks and bridge surface roughness are particularly considered. Specifically, two vehicle models are introduced, i.e., a simplified four degree-of-freedoms (DOFs) vehicle model and a more complex seven DOFs vehicle model, respectively. The bridges are modeled in two types, including a single-span uniform beam and a full scale reinforced concrete high-pier bridge, respectively. The crack zone in the reinforced concrete bridge is considered by a damage function. The bridge and vehicle coupled equations are established by combining the equations of motion of both the bridge and vehicles using the displacement relationship and interaction force relationship at the contact points between the tires and bridge. The numerical simulations and verifications show that the proposed modeling method can rationally simulate the vibration behaviors of the damaged bridge under moving vehicles; the effect of cracks on the impact factors is very small and can be neglected for the bridge with none roughness, however, the effect of cracks on the impact factors is very significant and cannot be neglected for the bridge with roughness.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.129-137
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• 2017

In this paper, we propose a digital controller design methodology for an LLC resonant converter which has been widely used due to the advantages of low switching loss and high efficiency. We establish a mathematical model of an LLC resonant converter using the extended describing function concept and propose a controller design method based on the Ziegler Nichols control parameter tuning criteria. The voltage controller of an LLC resonant converter is designed based on the derived small signal model and the performance of the controller is verified by MATLAB simulations. The validity and the control performance of the designed voltage controller for the LLC resonant converter is analyzed through some simulations for the case of load variations and circuit modeling errors.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.2
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• pp.9-14
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• 2011

This Paper proposed the prediction method of fuel consumption from vehicle informations through OBD-II Interface. We assumed RPM, TPS had a relationship with fuel consumption. We got the output as fuel-consumption from a vehicle RPM, TPS as input by using polynomial equation. We had modelling as quadric function with OBD-II data and fuel consumption data supported by automotive company in real. In order to verify the effectiveness of proposed method, 5 km real road-test was performed. The results showed that the proposed method can estimate precisely the fuel consumption from vehicle multi-data.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.1
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• pp.114-119
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• 2009

The authors have investigated the NVH problems of drive system in full vehicle test. However it is difficult to define the NVH problems of driveline system. Since it is hard to measure the rotating part and it is vague that only the drive system induces the NVH problem. Vibration in a driveline is presented in this paper. In the experiment, the rear sub-frame and propeller shafts and axle were composed and mounted with rubber each other. For applying the vibration input instead of the torsional vibration effect of an engine, the shaker was taken. In particular, torsional vibration due to fluctuating forced vibration excitation across the joint between driveline and rear sub-frame was carefully examined. Accordingly, the joint response was checked from experiments and the FE-simulation using FRF (frequency response function) analysis was performed. All test results were signal processed and validated against numerical simulations. In present study, the new test bench for measuring the vibration signal and simulating the vehicle chassis system was proposed. The modal value and the mode shape of components were analyzed using the CAE model to identify the important components affecting driveline noise and vibration. It could be reached that the simplified test bench could be well established and be used for design guide and development of the vehicle chassis components.

• Journal of the Ergonomics Society of Korea
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• v.36 no.2
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• pp.87-108
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• 2017

Objective: The purpose of this study was to precede the acceptance study based on automation steps and user experience that was lacked in the past study on the core technology of autonomous vehicle, ADAS. The first objective was to construct the acceptance model of ADAS technology that is the core technology, and draw factors that affect behavioral intention through user experience-based evaluation by applying driving simulator. The second one was to see the change of factors on automation step of autonomous vehicle through the UX/UA score. Background: The number of vehicles with the introduction of ADAS is increasing, and it caused change of interaction between vehicle and driver as automation is being developed on the particular drive factor. For this reason, it is becoming important to study the technology acceptance on how driver can actively accept giving up some parts of automated drive operation and handing over the authority to vehicle. Method: We organized the study model and items through literature investigation and the scenario according to the 4 stages of automation of autonomous vehicle, and preceded acceptance assessment using driving simulator. Total 68 men and woman were participated in this experiment. Results: We drew results of Performance Expectancy (PE), Social Influence (SI), Perceived Safety (PS), Anxiety (AX), Trust (T) and Affective Satisfaction (AS) as the factors that affect Behavioral Intention (BI). Also the drawn factors shows that UX/UA score has a significant difference statistically according to the automation steps of autonomous vehicle, and UX/UA tends to move up until the stage 2 of automation, and at stage 3 it goes down to the lowest level, and it increases a little or stays steady at stage 4. Conclusion and Application: First, we presented the acceptance model of ADAS that is the core technology of autonomous vehicle, and it could be the basis of the future acceptance study of the ADAS technology as it verifies through user experience-based assessment using driving simulator. Second, it could be helpful to the appropriate ADAS development in the future as drawing the change of factors and predicting the acceptance level according to the automation stages of autonomous vehicle through UX/UA score, and it could also grasp and avoid the problem that affect the acceptance level. It is possible to use these study results as tools to test validity of function before ADAS offering company launches the products. Also it will help to prevent the problems that could be caused when applying the autonomous vehicle technology, and to establish technology that is easily acceptable for drivers, so it will improve safety and convenience of drivers.

• Journal of Ocean Engineering and Technology
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• v.17 no.1
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• pp.1-7
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• 2003

Autonomous underwater vehicles (AUVs) are unmanned, underwater vessels that are used to investigate sea environments in the study of oceanography. Docking systems are required to increase the capability of the AUVs, to recharge the batteries, and to transmit data in real time for specific underwater works, such as repented jobs at sea bed. This paper presents a visual :em control system used to dock an AUV into an underwater station. A camera mounted at the now center of the AUV is used to guide the AUV into dock. To create the visual servo control system, this paper derives an optical flow model of a camera, where the projected motions of the image plane are described with the rotational and translational velocities of the AUV. This paper combines the optical flow equation of the camera with the AUVs equation of motion, and deriver a state equation for the visual servo AUV. Further, this paper proposes a discrete-time MIMO controller, minimizing a cost function. The control inputs of the AUV are automatically generated with the projected target position on the CCD plane of the camera and with the AUVs motion. To demonstrate the effectiveness of the modeling and the control law of the visual servo AUV simulations on docking the AUV to a target station are performed with the 6-dof nonlinear equations of REMUS AUV and a CCD camera.

• International Journal of Ocean System Engineering
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• v.3 no.2
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• pp.50-60
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• 2013

This paper presents a novel approach to the design of an adaptive fuzzy sliding mode controller for depth control of an autonomous underwater vehicle (AUV). So far, AUV's dynamics are highly nonlinear and the hydrodynamic coefficients of the vehicles are difficult to estimate, because of the variations of these coefficients with different operating conditions. These kinds of difficulties cause modeling inaccuracies of AUV's dynamics. Hence, we propose an adaptive fuzzy sliding mode control with novel fuzzy adaptation technique for regulating vertical positioning in presence of parametric uncertainty and disturbances. In this approach, two fuzzy approximator are employed in such a way that slope of the linear sliding surface is updated by first fuzzy approximator, to shape tracking error dynamics in the sliding regime, while second fuzzy approximator change the supports of the output fuzzy membership function in the defuzzification inference module of fuzzy sliding mode control (FSMC) algorithm. Simulation results shows that, the reaching time and tracking error in the approaching phase can be significantly reduced with chattering problem can also be eliminated. The effectiveness of proposed control strategy and its advantages are indicated in comparison with conventional sliding mode control FSMC technique.

• The Journal of Korea Robotics Society
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• v.12 no.1
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• pp.94-106
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• 2017

Unmanned military vehicles (UMVs) will be increasingly applied to the various military operations. These UMVs are most commonly characterized as dealing with "4D" task - dull, dirty, dangerous and difficult with automations. Although most of the UMVs are designed to a high degree of autonomy, the human operator will still intervene in the robots operation, and tele-operate them to achieve his or her mission. Thus, operator capacity, along with robot autonomy and user interface, is one of the important design factors in the research and development of the UMVs. In this paper, we propose the method to assess the operator capacity of the UMVs. The method is comprised of the 6 steps (problem, assumption, goal function identification, operator task analysis, task modeling & simulation, results and assessment), and herein colored Petri-nets are used for the modeling and simulation. Further, an illustrative example is described at the end of this paper.

• Journal of Ginseng Research
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• v.40 no.2
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• pp.196-202
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• 2016

Background: Ginsenoside Rd (GSRd), a main component of the root of Panax ginseng, exhibits anti-inflammation functions and decreases infarct size in many injuries and ischemia diseases such as focal cerebral ischemia. M1 Macrophages are regarded as one of the key inflammatory cells having functions for disease progression. Methods: To investigate the effect of GSRd on renal ischemia/reperfusion injury (IRI) and macrophage functional status, and their regulatory role on mouse polarized macrophages in vitro, GSRd (10-100 mg/kg) and vehicle were applied to mice 30 min before renal IRI modeling. Renal functions were reflected by blood serum creatinine and blood urea nitrogen level and histopathological examination. M1 polarized macrophages infiltration was identified by flow cytometry analysis and immunofluorescence staining with $CD11b^+$, $iNOS^+$/interleukin-12/tumor necrosis factor-${\alpha}$ labeling. For the in vitro study, GSRd ($10-100{\mu}g/mL$) and vehicle were added in the culture medium of M1 macrophages to assess their regulatory function on polarization phenotype. Results: In vivo data showed a protective role of GSRd at 50 mg/kg on Day 3. Serum level of serum creatinine and blood urea nitrogen significantly dropped compared with other groups. Reduced renal tissue damage and M1 macrophage infiltration showed on hematoxylin-eosin staining and flow cytometry and immunofluorescence staining confirmed this improvement. With GSRd administration, in vitro cultured M1 macrophages secreted less inflammatory cytokines such as interleukin-12 and tumor necrosis factor-${\alpha}$. Furthermore, macrophage polarization-related pancake-like morphology gradually changed along with increasing concentration of GSRd in the medium. Conclusion: These findings demonstrate that GSRd possess a protective function against renal ischemia/reperfusion injury via downregulating M1 macrophage polarization.