• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.36 no.8
• /
• pp.835-841
• /
• 2012

We measured the mechanical and thermal properties of four types of cast irons used for manufacturing the brake discs of railway vehicles. It was found that these properties could be controlled by varying the composition of Ni, Cr, and Mo. Thermal fatigue tests were carried out by using a thermal fatigue tester in which thermal cycles could be controlled. Thermal crack initiation and propagation were measured on cylindrical specimens. Finally, we simulated the thermal fatigue test procedure by finite element analysis and calculated the thermal fatigue lifetimes by Manson-Coffin's equation and the maximum principal strain. The estimated thermal fatigue lifetimes corresponded to the measured lifetimes when the total crack length was $40{\mu}m{\sim}1mm$.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.9
• /
• pp.1099-1107
• /
• 2013

This study proposes a weight reduction design for urban transit, specifically, a Korean EMU carbody made of aluminum extrusion profiles, according to size optimization and useful material changes. First, the thickness of the under-frame, side-panels, and end-panels were optimized by the size optimization process, and then, the weight of the Korean EMU carbody could be reduced to approximately 14.8%. Second, the under-frame of the optimized carbody was substituted with a frame-type structure made of SMA 570, and then, the weight of the hybrid-type carbody was 3.8% lighter than that of the initial K-EMU. Finally, the under-frame and the roof-panel were substituted with a composite material sandwich to obtain an ultralight hybrid-type carbody. The weight of the ultralight hybrid-type carbody was 30% lighter than that of the initial K-EMU. All the resulting carbody models satisfied the design regulations of the domestic Performance Test Standard for Electrical Multiple Unit.

• The Journal of Society for e-Business Studies
• /
• v.22 no.4
• /
• pp.103-115
• /
• 2017

Globally, frequency and scale of natural disasters are growing, also the damage is increasing. In view of the damage by natural disasters for several years, it is true that Korea is not free from such damages. In this paper, we propose a process to efficiently manage recovery resources in case of disaster damage. We utilize the IoT technology to detect the resource status in real time, and configure the process so that the state and movement of the recovery resource can be grasped in real time through the resource activity recognition module. In addition, we designed the database that is necessary to actualize it, and developed and experimented resource activity recognition module using smart-phone sensors. This will contribute to building a quick and efficient disaster response system.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.3
• /
• pp.1749-1755
• /
• 2014

Technique for analyzing a pile installed by vibrohammer was developed and parametric studies were executed in order to evaluate reliability of the developed technique. Comparing the accelerations obtained from parametric studies of varying eccentric moment and frequency, it can be seen that magnitude of maximum acceleration was proportional to the eccentric moment and square of frequency. It can also be seen that amplitude of displacement was roughly proportional to the eccentric moment but has nothing to do with the frequency. It can be said that all of the analysis results reflect characteristics of behavior of a pile in case of free vibration. Comparing the dynamic load transfer curves, maximum dynamic unit toe resistance was constant regardless of the eccentric moment and the frequency and it can be seen that dynamic unit skin friction was affected by the eccentric moment not by frequency. Comparing all of the analysis results, it can be said that the developed technique is reliable.

• The KIPS Transactions:PartA
• /
• v.17A no.1
• /
• pp.19-26
• /
• 2010

As standard of living is higher and aging society is coming, it is needed to develop transportation that is easy to use for weak person. To comply with the demands, it is started to make Bi-modal Tram that is on KRRI(Korea Railroad Research Institute)'s hands. This tram has to have good accessibility like bus, be low level from ground like subway, and park accurately so wheel chair's or passenger's foot can't fall into the gap. But Bi-modal Tram have long length, so it need development of All Wheel Steering System. The Bi-modal Tram that have all wheel steering system steer not only the first axle but also the second and third axle from the first axle or articulation angle, and velocity, and so on. At this study, we discuss AWS ECU's development process.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.2D
• /
• pp.175-182
• /
• 2012

Korea Train Express (KTX) is now leading the train industry, heralding a new renaissance of transportation and changing the old construction-oriented policy to one based on customers' needs that intends to offer better service in speed, convenience, and space creation around the railroad stations. These new policies aims to provide differentiated 'utility' based services, with the commitment to environmentally friendly 'green growth'. Nevertheless, the new policy has the unspecified 'public' as its target and tends to change bus users to train users rather than automobile users to train users. Furthermore, due to the heavy dependence on automobiles, there exists the definite limit of the new policy to attract the automobile users to train services. The purpose of this paper is to analyze the car dependence in Seoul metropolitan area. Based on the analysis using structure equation modeling, it can be described that environment consciousness and public satisfaction level affect on the car dependence. Author concludes that emotional marketing needs to go with utility marketing and Incentive marketing to weaken the heavy dependence on automobiles and to successfully prompt the change to train services.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.5
• /
• pp.2403-2407
• /
• 2012

Finite number of pile elements are considered in load transfer method. And section force and movement of each pile element are computed by considering compatibilities between pile displacement and the load transfer along a pile and between displacement and resistance at the tip of the pile. For the conventional load transfer method, large amount of computations due to iterations are needed. Formulation of finite difference equation from the differential equation which depicts pile behavior under axial loading was accomplished in order to simplify the computation for obtaining pile section forces and displacements. By comparing the results between the simplified computation method and the reported data, there was no difference between the two results.

• Journal of the Society of Disaster Information
• /
• v.10 no.1
• /
• pp.40-48
• /
• 2014

A number of attempts has been made to reinforce ballasted track substructure to meet the requirement of high-speed operation and effective rehabilitation of existing railroads. For the purpose of this, the use of geogrid has been applied, and the benefit of its use has been recognized via previous studies. In this study, an experimental pullout test was carried out to investigate the influence of normal stress on pullout strength of geogrid using different types of soil and geogrid. The results revealed that the pullout resistance generally tends to increase proportional to normal stress while the pullout coefficient interaction decreases, which is a function of material interface properties, such as the friction angle of soil, and interlocking condition between soil and geogrid. In addition, a methodology based on work-energy concept was proposed to evaluate effectiveness of geogrid and limitedly verified using test results.

• Journal of Microbiology and Biotechnology
• /
• v.15 no.3
• /
• pp.461-465
• /
• 2005

Characteristics of biological $CO_2$ fixation by Chlorella sp. HA-1 were investigated in a semi-continuous and series reactor system using an internally illuminated photobioreactor to overcome shortcomings of physicochemical technologies such as adsorption and membrane separation. High $CO_2$ fixation rate was achieved in the semi-continuous reactor system, in which the dilution ratios of the culture medium were controlled. The average $CO_2$ fixation rate was maintained almost constantly when the dilution ratio increased by 0.1 increment from the initial value of 0.5. The total removal efficiency of $CO_2$ was enhanced by employing a series reactor system. The average $CO_2$ fixation rate increased until 4.013 g $CO_2\;day^{-1}$ in a series operation of four reactors, compared to 0.986 g $CO_2\;day^{-1}$ in a batch operation mode. The total $CO_2$ fixation rate was proportional to the number of reactors used in the series reactor system. In the series reactor system of semi-continuous operation, a large amount of $CO_2$ was removed continuously for 30 days. These results showed that the present reactor systems are efficient and economically feasible for a biological $CO_2$ fixation.

• Journal of the Korean Geotechnical Society
• /
• v.33 no.12
• /
• pp.75-80
• /
• 2017

Permeable block pavement systems are widely used to relieve the flood and enhance water circulation. However, domestic design method has not yet been established well. Although AASHTO 93 flexible pavement design method is applied as a structural design method outside the country, there is a lack of information on layer coefficient of the permeable pavement materials, which makes it difficult to apply the design to various materials. Therefore, in this study, a method of calculating the layer coefficient of permeable block pavement materials by plate load test was presented and the layer coefficient of a permeable block pavement in a testbed was evaluated. Overall, calculated layer coefficient of open graded aggregate and permeable block pavement surface layer were similar to those of the conventional values. The presented method may be used to evaluate layer coefficients of permeable block pavements for design.