• 전기의세계
• /
• 제23권6호
• /
• pp.36-37
• /
• 1974

본고에서는 다음의 내용을 다루었다. 1. 초고속전철과 Linear Motor 2. 주행차의 부상과 안정화 방법 3. 자기부상주행시험차의 예

• International Journal of Highway Engineering
• /
• 제6권3호
• /
• pp.37-46
• /
• 2004

This study was performed to establish valid methodology for determining dynamic stability(DS) of deformation-cycle curve which is obtained through wheel tracking(WT) test, the most widely used method for forecast of rutting tendency of asphalt mixture. Existing Korean and Japanese methods for DS are unrealistic and do not really reflect characteristics of rut resistance of asphalt concretes especially when the slope of deformation-cycle curve is stabilized at the end. It was proved that the new DS developed in this study reflected rut resistance characteristics better than existing methods. It is especially effective to distinguish the mixtures with high DR(depth of rut) but stable slope at the end of curve from the mixture with lower DR and continuous slope. The field evaluation must be followed to prove whether the mixture which shows a high DS value this method perform well in the filed.

• Journal of IKEEE
• /
• 제27권1호
• /
• pp.1-11
• /
• 2023

Path driving tests are necessary for the development of self-driving cars or robots. These tests are being conducted in simulation as well as real environments. In particular, for development using reinforcement learning and deep learning, development through simulators is also being carried out when data of various environments are needed. To this end, it is necessary to utilize not only manually designed paths but also various randomly and automatically designed paths. This test site design can be used for actual construction and manufacturing. In this paper, we introduce a method for randomly generating a driving test path consisting of a combination of arcs and segments. This consists of a method of determining whether there is a collision by obtaining the distance between an arc and a line segment, and an algorithm that deletes part of the path and recreates an appropriate path if it is impossible to continue the path.

• Transactions of the KSME C: Technology and Education
• /
• 제5권2호
• /
• pp.115-126
• /
• 2017

This paper proposes an accelerated life evaluation of drive shaft for the power train parts of special purpose vehicle. It is necessary the real load data of usage level driving load condition for life evaluation of power train parts, but we can't get the load spectrum data for evaluation in many case of special purpose vehicle. So, in this paper, the road load spectrum data for evaluation is created by modeling and simulation based on vehicle data and special road condition. The inverse power model is used for accelerated life test. The equivalent torque of load spectrum is achieved using the Miner's Rule. This paper also proposes the calibrated acceleration life test method for drive shaft. The fatigue test is performed through three stress levels. The lifetime at normal stress level is predicted by extrapolation, and is verified through comparison of experimental results and load spectrum data.

• International Journal of Highway Engineering
• /
• 제11권4호
• /
• pp.25-31
• /
• 2009

In general, it is well known fact that the stone mastic asphalt (SMA) pavement has a high resistance against rutting. However, performance of SMA is not well measured by general method used in the laboratory. The objective of this study is to investigate an applicability of deformation strength ($S_D$) for performance estimation of SMA, and to find out the correlation between rut depth and dynamic stability, and $S_D$ of SMA. This study carried out wheel tracking test and Kim-test with optimum asphalt content (OAC) determined by mix design. The results indicated that the $S_D$ of SMA was very poorer than those of dense-graded asphalt mixtures. $S_D$ showed similar WT dynamic stability and rut-depth level. It was found that Kim-test was not reflected higher rutting resistance of SMA like as indirect tensile strength (ITS) test and Marshall stability test. Also, it was revealed that dynamic stability and rut-depth of WT had some problems to estimate rutting resistance of SMA mixtures.

• International Journal of Highway Engineering
• /
• 제2권1호
• /
• pp.135-145
• /
• 2000

A new procedure needs to be developed to predict the dynamic layer properties under moving truck loads. In this study, a computer code to evaluate layer moduli of asphalt concrete pavement from measured interior deflections at various depths were developed and verified from numerical model tests. Interior deflections of the pavement are measured from Multi-Depth Deflectometer(MDD). It was found that errors between the given and backcalculated moduli in numerical analysis were less than 0.32% for several numerical models tested. When impact loads were used, a technique to determine the depth to virtual rigid base was proposed through the analysis of compressive wave velocity and impulse loading durations. It was found that errors between the given and backcalculated moduli in numerical analysis were less than 0.114% when virtual rigid base was considered in numerical analysis. The pavement behavior must be evaluated under various vehicle speeds when determining the dynamic interaction between the loading vehicle and pavement system. To evaluate the dynamic behavior on asphalt concrete pavement under various vehicle speeds, truck moving tests were carried out. From the test results with respect to vehicle speed, it was found that the vehicle speed had significant effect on actual response of the pavement system. The lower vehicle speed generates the higher interior deflections, and the lower dynamic modulus.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• 제26권5D호
• /
• pp.831-838
• /
• 2006

An experimental/analytic study has been conducted to understand the adverse effects of low vehicle speed, high axle load and high tire pressure on the performance of asphalt pavements. Of 33 asphalt sections at KHC test road, two sections having different base layer thickness (180 mm versus 280 mm) are adopted for rollover tests. During the test, a standard three-axle dump truck maintains a steady state condition as moving along the wheel path of a passing lane, and lateral offsets and real travel speed are measured with a laser-based wandering system. Test results suggest that vehicle speed affects both longitudinal and transverse strains at the bottom of asphalt layer (290 mm and 390 mm below the surface), and even slightly influences the measured vertical stresses at the top of subbase and subgrade due to the dynamic effect of rolling vehicle. Since the anisotropic nature of asphalt-aggregate mixtures, the difference between longitudinal and transverse strains appears prominent throughout the measurements. As the thickness of asphalt pavement increases, the measured lateral strains become larger than its corresponding longitudinal strains. Over the limited testing conditions, it is concluded that higher axle weight and higher tire pressures induce more strains and vertical stresses, leading to a premature deterioration of pavements. Finally, a layered elastic analysis overestimates the maximum strains measured under the 1st axle load, while underestimating the maximum vertical stress in both pavement sections.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• 제20권9호
• /
• pp.29-34
• /
• 2019

In this study, a gasoline test vehicle was evaluated for drive quality in emissions and fuel economy tests. The measurement results were compared with the manufacturer's suggested values to evaluate whether the tolerance ranges (fuel efficiency -5%, greenhouse gas +5%) were exceeded. We carried out tests with test subjects based on the SAE J2951 evaluation method. The test vehicle was a 2L gasoline vehicle. The drive following performance was found to increase under deliberate driving conditions and decreased in smooth driving conditions. As a result of the analysis of the drive following performance, the closer the value is to 1, the more accurate the driving is. (-) indicates harsh conditions, and (+) indicates gentle conditions. The basic data on the driver following between testers was obtained by analysis of the tests. The fuel efficiency correlation with the drive following performance within the target speed range of the fuel consumption mode. In the future, these measurement results can serve as key data for securing an exhaust gas database and fuel efficiency system for each measurement mode.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• 제40권8호
• /
• pp.743-750
• /
• 2016

Track rollers are the key parts that support the weight applied to the caterpillar track of construction machinery. The operating conditions of construction machinery are harsh; hence, the track rollers exposed to these conditions can experience failures such as oil leakage and breakdown of the machine, because of impacts during driving. The failure of track-rollers has a major effect on the operation of the construction machinery. Therefore, each manufacturer tries to evaluate the performance of their products by conducting a self-test. However, only the vertical loads applied to the track rollers are considered in most of the self-tests. This method has the problem of ignoring the horizontal loads that are applied to the track rollers while rotary driving, and hence it does not create the practical operating condition of the construction machinery. In this study, we have determined the experimental conditions that effectively consider the magnitudes of the vertical and horizontal loads. The results of simulations and experiments conducted to assess the influence of horizontal loads on the failure of track rollers are presented in this paper.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
• /
• pp.534-537
• /
• 2008

하이브리드자동차의 연료소비율 시험 시 초기 SOC 조건에 따른 SOC와 연비 변화 특성을 파악하기 위해 2종의 차종을 선택하여 UDDS 모드주행 실험을 실시하였다. 실험결과 Strong type 자동차는 주행시작 약 550초 경과 후 SOC 52 $\sim$ 54%로 수렴하였다. 또한 일반 시가지 주행조건에서는 SOC를 50$\sim$55 % 범위에서 제어함을 알 수 있으며, 초기 SOC 조건에 따라 연비는 약 79%의 편차가 나타났다. 이는 저속구간에서 순수 전기자동차 구동이 구현됨으로써 SOC 70%에서 큰 연비 상승 효과가 나타나는 것으로 판단 된다. Mild type 자동차는 연비가 초기 SOC 조건에 따라 약 5%의 편차가 나타남을 알 수 있었으며, SOC 변화특성은 배터리 충전상태에 따라 충전량 제어는 이루어지나 가속 시 어시스트만 이루어지는 시스템적 특성상 효율적인 SOC 제어가 이루어지지 않아 연비에는 큰 영향을 주지 않는 것으로 생각된다.