• Journal of Korean Society of Transportation
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• v.34 no.3
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• pp.234-247
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• 2016

As the necessity of the evaluation of environmentally-friendly traffic operations strategies becomes obvious, the characteristics of fuel consumption models should be comprehended in advance. This study selected three fuel consumption models developed in Korea and another three models widely used in North America, and compared their applicabilities. Specifically, the national institute of environmental research (NIER) drive modes and the VISSIM software were utilized to model various driving patterns, and their fuel consumptions were estimated using the fuel consumption models. Based on the results, all the models showed the similar results in the analysis of the most fuel efficient cruising speed. On the other hand, caution should be taken when using the KR-1 and KR-2 models in microscopic analyses because they are not sensitive to instantaneous power requirements of vehicles.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.1
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• pp.73-81
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• 2011

The performance of emission factor has been validated by comparison with on-road test data. Emission factor, which is a function of vehicle speed, has been acquired based on chassis dynamometer test with NIER driving pattern. Portable Emission Measurement System, PEMS has measured on-road emission. Test vehicle was operated on defined test routes under different driving conditions, and made ten trips along its route. Emission factors properly simulate on-road test result, although there is some drawback to consider variety of driving condition on real world. Vehicle specific power and acceleration have been used to explain the distributed on-road result within same vehicle speed range. The trend in carbon dioxide and nitrogen oxide emission with respect to specific power and acceleration is clear. It has been found that specific power is a good explanatory variable for microscopic analysis for modal test result. Acceleration is good for microscopic as well as macroscopic analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.82-88
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• 2018

This study investigated the structure of an 8-pole 8-slot linear generator, which acts as an electromagnetic damper by combining the structure of an electromagnetic suspension device capable of generating electrical energy through energy harvesting by absorbing the vibration energy from the road surface while driving. To compare the energy harvesting effect of the electromagnetic suspension according to the actual road surface, a driving road test was simulated for two actual road conditions, an asphalt road surface and unpacked road surface condition, using a civilian combined vehicle model in conjunction with a vehicle simulation program, Carsim and Simulink. As a result, the relative displacements of the suspensions on the asphalt road surface and the unpaved road were 8 mm and 13 mm, respectively. By applying the suspension displacement value derived by modeling the linear generator coupled to the electromagnetic suspension, the simulation was then performed for an analysis time of 0.3s by applying the same analytical conditions using the commercial electromagnetic analysis program, ANSYS MAXWELL, The average power generation on the unpacked roads and asphalt roads was 198.6W and 98.7W respectively, which was 103.7% higher for unpackaged roads. Finally, to compare the sensitivity of the road surface frequency and the suspension input displacement to the power generation output, the sensitivity of the two variables was 1.725 and 1.283, respectively, and the road surface frequency had a 34.5% higher effect on the average power generation.

• Journal of the KSME
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• v.29 no.3
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• pp.317-325
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• 1989

광학시 비접촉 미소 변위 계측 장치의 응용예는 앞서 소개한 응용 외에도 여러 분야에서 많이 활용되고 있다. 즉, 주행 중인 차량 바퀴의 얼라이먼트(alignment) 계측에 이용되기도 하며, 파괴 역학 분야에서 크랙 개구단부(COD)의 변위량 측정에도 이용되며, 충격 역학 분야에서는 변위의 출력 응답 특성이 경시적으로 대단히 복잡하게 변하는 동적 파괴 현상의 원인 규명의 목적으 로도 많이 활용되고 있다. 더욱이 눈부신 발전을 거듭하고 있는 재료 요소 기술 및 센서 기술의 도움으로 앞으로는 이러한 비접촉식 미소 변위 측정 시스템이 보다 더욱 다양하게 사용되어질 것으로 기대되며, 또한 점차 성능 및 가격적 측면에서도 고성능의 계측 시스템을 손쉽게 큰 부 담이 없이 구입 가능할 수 있으리라 믿는다. 그러나 한편으로는 고정도의 물리량의 계측은 꼭 최신의 고가의 장비로만 되는 것이 아니라는 점과, 이러한 계측 시스템의 활용 시에는 기본 검출 원리 및 특성의 이해와 더불어 각 시험 경우에 따른 측정치에 대한 검증 작업을 게을리 하지 말아야 된다는 점도 아울러 당부하고자 한다.

• The Journal of Korean Institute for Practical Engineering Education
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• v.2 no.1
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• pp.154-163
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• 2010

The object of this study is to investigate the penetration characteristics according to the change of stacking sequences and curvature radius in the composite laminated shell. They are staked to [02/902]S and [0/902/0]s, their interlaminar number are two and four. We are manufactured to composite laminated shells with various curvature radius. Curvature radius of composite shell is 100, 150, 200mm and ${\infty}$(it's meaning flat-plate). In general, kinetic energy after impact-kinetic energy before impact increased linearly in all specimens. Absorbed energy increased linearly as the curvature increased, and absorbed energy of [02/902]S specimen, which is small interlaminar number, was higher than [0/902/0]s specimen.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.6
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• pp.577-583
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• 2011

To meet the requirements of the Tier 4 interim regulations for off-road vehicles, emissions of particulate matter (PM) and nitrogen oxides (NOx) must be reduced by 95% and 30%, respectively, compared to current regulations. In this research, both the DPF and HPL EGR systems were investigated, with the aim of decreasing the PM and NOx emissions of a 56-kW off-road vehicle. The results of the experiments show that the DOC-DPF system is very useful for reducing PM emissions. It is also found that the back pressure is acceptable, and the rate of power loss is less than 5%. By applying the HPL EGR system to the diesel engine, the NOx emissions under low- and middle-load conditions are reduced effectively because of the high differential pressure between the turbocharger inlet and the intake manifold. The NOx emissions can be decreased by increasing the EGR rate, but total hydrocarbon (THC) emission increases because of the increased fuel consumption needed to compensate for the power loss caused by EGR and DPF.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.4
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• pp.127-132
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• 2022

Among the electrical components mounted on railroad cars, the largest load is the main transformer, which has a low power density of 0.2~0.4 MVA/ton due to the low operating frequency(60Hz), which is an important factor for weight reduction. Therefore, research on molded transformers, semiconductor transformers, etc. is being actively conducted at Domestic and foreign in order to improve the main transformer for railway vehicles. Meanwhile, attempts are being made to apply a permanent magnet synchronous motor (PMSM) to replace an induction motor as a traction motor that is mostly applied to domestic and foreign railway vehicles. Permanent magnet synchronous motors (PMSMs) can secure higher power density and efficiency compared to induction motors, but have disadvantages in that the materials required for manufacturing are expensive and design is somewhat difficult compared to induction motors. Considering these problems, in this paper, we suggest that a small and lightweight semiconductor transformer is applied, and a simple structure, high torque, low cost SRM can be applied in accordance with the requirements such as weight reduction and high efficiency of railroad vehicles. content.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.1
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• pp.73-80
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• 2016

The Car License Plate Recognition(: CLPR) is required in searching the hit-and-run car, measuring the traffic density, investigating the traffic accidents as well as in pursuing vehicle crimes according to the increasing in number of vehicles. The captured images on the real environment of the CLPR is contaminated not only by snow and rain, illumination changes, but also by the geometrical distortion due to the pose changes between camera and car at the moment of image capturing. We propose homographic transformation and intensity histogram of vertical image projection so as to transform the distorted input to the original image and cluster the character and number, respectively. Especially, in this paper, the Multilayer Perceptron Algorithm(: MLP) in the CLPR is used to not only recognize the charcters and car license plate, but also determine the optimized ratio among the number of input, hidden and output layers by the real experimental result.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.4
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• pp.456-465
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• 2019

PHEV(Plug in Hybrid Electric Vehicle) and BEV(Battery Electric Vehicle) equip high voltage batteries to drive motor and vehicle electric system. Those vehicle require OBC(On-Board Charger) for charging batteries and LDC(Low DC/DC Converter) for converting from high voltage to low voltage. Since the charger and the converter actually separate each other in electrical vehicles, there is a margin to reduce the vehicle weight and area of installation by integration two systems. This paper studies a 1.5kW LDC converter that can be integrated into an OBC using an isolated current-fed converter by simplifying the design of LDC transformers. The proposed LDC can control the final output voltage of the LDC by using a fixed arbitrary output voltage of the bidirectional buck-boost converter, so that Compared to the existing OBC-LDC integrated system, it has the advantage of simplifying the transformer design considering the battery voltage range, converter duty ratio and OBC output turn ratio. Prototype of the proposed LDC was made to confirm normal operation at 200V ~ 400V input voltage and maximum efficiency of 91.885% was achieved at rated load condition. In addition, the OBC-LDC integrated system achieved a volume of about 6.51L and reduced the space by 15.6% compared to the existing independent system.

• Journal of ILASS-Korea
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• v.21 no.4
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• pp.214-222
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• 2016

Changes in road infrastructure affect driving patterns and pollutant emission characteristics. we analyzed the changes in driving patterns and pollutant emission characteristics of the driving route via measured driving patterns at year 2009 and 2016. Since 2009, there has been an increase in population and traffic demand, including residential areas and industrial facilities. Traffic conditions were improved such as the opening of the highway Inter-Change to Seoul and the construction of underground driveway. As a result, the average vehicle speed increased. More detail comparisons have made on the changes of the underground driveway section and the crossroad section, which are expected to have significant changes in the transportation infrastructure. The vehicle speed distribution of the underground driveway changed from low speed to high speed, and the increase of the time spent at the high speed and high load caused the increase of NOx emissions. The vehicle speed also increased at the crossroad section, and the consequence NOx and $CO_2$ emissions decreased. It is mainly because the decreased time spent at idle, which results from the proper traffic demand management at this area.