• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3335-3340
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• 2007

The government have been tightening EM regulation gradually but the effect is not good because of rapid increase of vehicles. And medium & heavy duty diesel vehicles, even though the number is small, exhaust very large pollutants(about over 50%). Especially it is more severe about old trucks and buses. Accordingly, CNG vehicle and the retrofit of diesel to CNG must be an alternative in order to protect the atmospheric environment and improve the air quality in the metropolitan area. The main object of this study is to secure the retrofit technology of diesel to CNG vehicle and the management system of CNG engine. we passed the government emission certification test. In addition to this, the mass production for retrofit is also studied. Results of emission and durability test for certification are as follows; there was no problem during 30,000km vehicle durability test and good emission levels satisfying the regulation.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.16 no.4
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• pp.75-82
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• 2008

As the number of passengers and the amount of cargo is getting increased, the traffic of aircraft and moving vehicle at an airport is getting busy. Especially, due to the heavy traffic of moving vehicles in the area of airside, the safety management of them is getting important. The study has been performed for suggesting improved methods in order to reduce safety accidents between aircraft and moving vehicles by introducing a safety management system for moving vehicles in airside of an airport. In order to improve the level of safety with the efficient management of moving vehicles in airside, the analysis of the domestic and international trends of the related technology and regulations has been performed. As a result, the conceptual design of safety management system has been suggested by utilizing the location information technology and four layers (hardware, network, middleware and application) approaches of safety management system.

• Journal of Power System Engineering
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• v.17 no.6
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• pp.130-135
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• 2013

It is a research about the change in reduction efficiency and performance resulting from installation of the EGR cooler, which is the core technology reducing NOx in response to standards been tightened of exhaust controls for off-road vehicle. It can reduce NOx by altering combustion temperature and oxygen concentration by recycling high-temperature exhaust gas. The target engine was large diesel engine for construction machine through by which we were able to verify a rate of change in output and capabilities for a heat-exchange within cooler itself depending on the existence of EGR cooler system. We have acquired a emission reduction technology for a construction machine by testing the reduction performance and rate of change in output.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.4
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• pp.907-920
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• 2015

By increase owning vehicle, infrastructure that accept vehicle is very poor on present that People's commuting is rapidly change to vehicle-use-form in metropolitan area. Although Transportation demand management is enforced, traffic is heavy but studies lake in internal and external. This study select Transportation demand management that enforce in internal and external and do a survey. Based on this survey, conduct AHP (Analytic Hierarchy Process) analvsis, Transportation demand management that enforce internal and external compare, decide superiority and understand every particular items' importance and satisfaction that users think. Also based on importance that collect by AHP analysis compare Transportation demand management character. Finally figure that grasped by this study, analysis present, found future TDM course and applicate future transportation improvement.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.2
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• pp.48-61
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• 2020

The objective of this study is to estimate traffic capacity based on the heavy-vehicle ratio in a two-lane freeway work zone where one lane is blocked by construction. For this, closed circuit television (CCTV) video data of the freeway work zone was collected, and the congestion at an upstream point was observed. The traffic volume at a downstream point was analyzed after a bottleneck was created by the blockage due to the upstream congestion. A distribution model was estimated using observed-time headway, and the road capacity was analyzed using a goodness-of-fit test. Through this process, the general capacity and an equation for capacity based on the heavy-vehicle ratio passing through the work zone were presented. Capacity was estimated to be 1,181~1,422 passenger cars per hour per lane (pcphpl) at Yeongdong, and 1,475~1,589pcphpl at Jungbu Naeryuk. As the ratio of heavy vehicles increased, capacity gradually decreased. These findings can contribute to the proper capacity estimation and efficient traffic operation and management for two-lane freeway work zones that block one lane due to a work zone.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.419-425
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• 2019

The objective of this study was to investigate the cooling performance characteristics of a hybrid refrigeration system in a heavy duty vehicle. The tested hybrid refrigeration system had additionally an electric compressor besides the present mechanical compressor for selective use according to the operating conditions. The applied electric compressor was a scroll type and with 18.0 cc displacement. In order to analyze the performance characteristics of the hybrid refrigeration system with respect to the cooling capacity and Coefficient of Performance (COP), other components, including two different types of compressors, were installed and tested under various operating conditions such as compressor speed and air flow rate of the evaporator. When the electric compressor was operated at 4,500 rev/min, the cooling capacity was about 4.0kW and COP was 3.5. When the mechanical compressor was operated, whereas the cooling capacity was higher than the electric controlled compressor, COP was lower due to the larger displacement and higher power consumption. To analyze the hybrid system operating characteristics due to reasonable cooling capacity with electric compressor operation, the mechanical compressor and electric compressor were operated by turns every 10 minutes under certain system operating conditions. Because surge pressure occurred when both compressors were switched on, the operating strategy required some time to balance the system pressure.

• International Journal of Highway Engineering
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• v.19 no.6
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• pp.13-21
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• 2017

PURPOSES : In this research, an SB3-level roadside barrier for a highway transition zone that meets the newly established guide Installation and Management Guide for Roadside Safety Appurtenance is developed. Its performance is evaluated by a numerical simulation and real-scale vehicle impact test. METHODS : The commercial explicit dynamic software LS-DYNA is utilized for impact simulation. An FE model of a passenger vehicle developed and released by the National Crash Analysis Center (NCAC) at George Washington University and a heavy goods vehicle (HGV) model developed by the TC226/CM-E Work Group are utilized for impact simulation. The original vehicle models were modified to reflect the conditions of test vehicles. The impact positions of the passenger vehicle and truck to the transition guardrail were set as 1/2 and 3/4 of the transition region, respectively, according to the guide. RESULTS : Based on the numerical simulation results of the existing transition barrier, a new structural system with improved performance was suggested. According to the result of a numerical simulation of the suggested structural system, two sets of transition barriers were manufactured and installed for real-scale vehicle impact tests. The tests were performed at a test field for roadside safety hardware of the Korea Highway Corporation Research Institute. CONCLUSIONS : The results of both the real-vehicle impact tests and numerical simulations of the developed transition barrier satisfied the performance criteria, and the results of numerical simulation showed good correlation with the test results.

• Journal of the Korea Safety Management & Science
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• v.14 no.3
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• pp.175-181
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• 2012

This example was able to focus on the long usage of the pavement that it was merely through the oxidation of the asphalt pavement which it could contact with on the road in the industrial housing complex and correlation regulation of the asphalt subsidence with the load in basic Infra of the configuration. The problem in conjunction with the subsidence (transformation) was interpreted as a problem of the subsidence of each pavement layer to lead the subsidence of the road or the transformation to packaging side asphalt pavement, but the traffic number of times of the heavy vehicle highlights for main problems with the road where is concentrated. In the case of general asphalt paving, it thinks it exposes light, and to study a general phenomenon for the asphalt transformation and a cause for a pavement construction method and the property of material used for pavement and a complement method by the case study at this time of the compound with the heavy vehicle traffic that it can become clear that small success transformation occurs at a point in time when 1-2 years more pass, and a fatigue rift occurs by ultraviolet rays, the oxidation with the contact with the air afterwards, and described beginning to use by the above.

• IE interfaces
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• v.25 no.1
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• pp.134-141
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• 2012

The steering gear box for mid-heavy duty electric vehicles are usually produced by only a few specialized companies. The special techniques, such as designing, producing and testing technology have been veiled. For this reason, steering gear boxes are imported from other country. The durability test with the electric vehicle which is satisfies the design parameters takes several years, and a prototype is installed in the real vehicle for the test. In this research, the steering gear box of the steering system was developed based on the reverse engineering and the testing methods and the steering gear box development process have been suggested. The prototype is also developed with the CAD and CAE tools. Developed steering gear box have been tested in torque tester and have satisfied requied torque. As a result, the process and testing methods studied in this research are useful in the development processes of electric vehicles steering system.

• Smart Structures and Systems
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• v.29 no.5
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• pp.661-675
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• 2022

In this paper, an electric vehicle drives with efficient control and low cost hardware using four quadrant DC converter with Permanent Magnet Direct Current (PMDC) motor fed by DC boost converter is presented. The main idea of this work is to improve the energy efficiency of the conversion chain of an electric vehicle by inserting a boost converter between the battery and the four quadrant-DC motor chopper assembly. Consequently, this method makes it possible to maintain the amplification gain of the 4 quadrant chopper constant regardless of the battery voltage drop and even in the presence of a fault in the battery. One of the most important control problems is control under heavy uncertainty conditions. The higher order sliding mode control technique is introduced for the adjustment of DC bus voltage and mechanical motor speed. To implement the proposed approach in the automotive field, experimental tests were carried out. The performances obtained show the usefulness of this system for a better energy management of an electric vehicle and an ideal control under different operating conditions and constraints, mostly at nominal operation, in the presence of a load torque, when reversing the direction of rotation of the motor speed and even in case of battery chamber failure. The whole system has been tested experimentally and its performance has been analyzed.