• Proceedings of the KSR Conference
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• 2004.10a
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• pp.216-221
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• 2004

The performance of secondary suspension is one of the most important characteristics of railway vehicles in the regard of vibration and riding comfort. For this reason, the suspension shall be designed to absorb vibration energy effectively and to avoid the resonance which would be occurred by the vibration of the bogies in driving. The main factor of characteristics of suspension is spring coefficient of air spring, and this paper shows how to achieve the desired coefficient and the results of the tests of new air springs.

• Journal of the Korean Society for Railway
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• v.6 no.3
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• pp.203-208
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• 2003

With designing alignment of railway for urban rail transit, a greater attention is paid to the riding safety and the comfort of the passengers. Especially, cant, transition curve, minimum curve radius are considered as very important alignment factors for the curve. For the above alignment factors, in this study, comparative studies on the design criteria of foreign rail transit are conducted. And reasonable design criteria of the alignment for urban rail transit are proposed.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.297-302
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• 2003

With designing alignment of railway for urban rail transit, a greater attention is paid to the riding safety and the comfort of the passengers. Especially, cant transition curve, minimum curve radius are considered as very important alignment factors for the curve. For the above alignment factors, in this study, comparative studies on the design criteria of foreign rail transit are conducted. And reasonable design criteria of the alignment for urban rail transit are proposed.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1270-1275
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• 2006

Korean Train Express (KTX) has opened to commercial traffic since 2004 at maximum speed 300km/h, and Korea High-speed Railway (HSR-350x) was developed by Korean government, several institutes, and related companies. HSR-350x is now being investigated its performance and tested at the high speed line. In 2004 December, HSR-350x was run over 350km/h and proved its running performance. In vehicle system, the faster the vehicle runs, the more vibration increases. To improve the riding comfort of high-speed trains, it needs to devise the vibration absorber. In this paper, we propose the installation of the semi-active damper to the power car of HSR 350x and present the specification and the damping characteristics.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.255-261
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• 1998

The train automatic operation control system is an on-board train control system that is widely adopted in modern rapid transit systems. The control system consists of TCMS(Train Control and Monitoring System), ATC(Automatic Train Control), ATO(Automatic Train Operation) and TWC(Train to wayside communication) in the train and wayside facilities. The functions of the system is to regulate train riding comfort, to service limited speed and smoothness during start, acceleration, constant speed travel, and fixed point parking under the corresponding commands. The paper describes the simulation model of the train automatic operation control of subway system, configuration of simulator hardware and software and operational algorithms.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1090-1095
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• 2008

Track geometry changes by traffic loads. The bigger the changes are, the worse the riding comfort and running stability of train. This is so-called track irregularity and is the most important quality parameters of ballasted track. To objectively assess track irregularity, track geometry should be able to be measured. Practically, railway companies use moving chord method, which determine versine values via a chord. The versine is the vertical distance to curve measured in the middle of the chord. This type of method measures only versine of track irregularity curve by transfer function from the characteristics of measuring device. In this report, review the characteristics of two types of measuring tools by comparing the measurements. The one is GRP-1000 system, optical surveying system with Total station and lazar prism trolley. This calculates track geometry by surveying absolute coordinates of two points each on both rail heads. The other is EM-120, measures versine with 10m of symmetrical chord length.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.3
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• pp.607-616
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• 2015

The demand for cars has been so steadily increasing based on the economic growth that the number of registered cars reached 18,870,000 as of the end of December, 2012. Due to this, the demand for the parking lots also rises continuously. Because of the limited ground space, the buildings ever becoming larger, and the trend of underground parking spaces, recent parking spaces are generally constructed underground. Accordingly, the parking lot ramps slope is limited to less than 17% by relevant laws to ensure the driver safety. However, when a driver enters a parking lot ramps whose slope is slightly steep, he frequently experiences his car body colliding with ramp brackets and often sees the scratches on ramp floor. Thus, this study is intended to prevent any damage to a structure and to contribute to ensuring the riding comfort and safety of drivers and passengers by presenting the details of proper vertical curve to prevent the collision of vehicles with ramp brackets through a vertical analysis of the first and last parts of a parking lot ramps. Because it is necessary to decide the appropriate and suitable vertical slope of a parking lot ramps, this study first identified the problems through site inspection, targeting the parking lot ramps of large buildings frequently that are used by many random people. Next, the possibility of mutual collision was assessed through a theoretical analysis of the first and last parts of a parking lot ramps. Lastly, the vertical curve of a parking ramp was analyzed to estimate its details, which was presented in this study. In conclusion, if the vertical curve presented through this study is used, it will help prevent any damage to the cars and structures, ensure the riding comfort and safety of the drivers, and further reestablish the criteria for vertical installation of a parking lot ramps.

• Journal of the Korean Society of Clothing and Textiles
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• v.44 no.4
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• pp.739-748
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• 2020

In this study, a wrist protector was manufactured and designed using 3D printing technology to prevent wrist pain when riding a bicycle with a high forward-tilted saddle. The efficiency of the design was analyzed in objective and subjective evaluations. First, seven women in their twenties selected their most preferred design by subjective evaluation from among three 3D wrist protectors. Then electromyography (EMG) was measured and subjective sensations were evaluated while wearing and not wearing the preferred 3D wrist protector as selected by cyclists. Experimental results showed that a wrist-bending angle of 30 degrees was most favored. When the 3D wrist protector was worn, muscle activity was smaller at the flexor carpus radialis position than when the 3D wrist protector was not worn; muscle fatigue was also lower. In the subjective evaluation, the 3D wrist protector was more comfortable than no protector, and wrist fatigue was also lower. In addition, the wrist protector was rated positively for its design suitability, size adequacy, ease of operation, and fit; however, cyclists felt that a little more cushioning was needed.

• Journal of Power Electronics
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• v.17 no.2
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• pp.358-367
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• 2017

This paper presents a novel filtering method for speed measurements to improve the low-speed performance of the direct-drive permanent magnet traction machines for elevators. Based on the theory of nonlinear tracking differentiator (NTD), this method, which can act as a high performance filter of a raw speed signal, obtains a more accurate speed feedback signal when applying a low-resolution encoder. In addition, it can relieve the interference caused by the position derivative for speed sampling. By analyzing the frequency response of the NTD, the influence of its parameters on the performance of the speed filtering is investigated. Compared with different types of low-pass filters, the proposed method shows a shorter time delay and a stronger ability in terms of noise suppression when the parameters are selected carefully. In addition, when using the measured speed signal through a nonlinear tracking differentiator as the feedback of the system, the motor runs more steadily at low speeds. As a result, the riding comfort of a direct-drive elevator can be improved. The feasibility of the proposed strategy was verified on an 11.7kW elevator traction machine using a commercial inverter.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.1
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• pp.90-96
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• 2011

The shock absorber base assembly is one of the parts in the shock absorber equipment that controls the vehicle movement. It absorbs the shock and vibration to guarantee riding stability and comfort. It demands strength, reliability and strict airtightness of the welded section because the shock absorber base assembly is a container which resists pressure and needs durability by being filled with gas and oil. However, the current engineering needs a lot of production time, has a high cost and shows a low production rate. These problem due to the eight production processes, four of which are spot welding, reinforcement welding like metal active welding (MAG), prior process of the base assembly cap and tube for precision and pressing. We will analyze the manufacturing processes of the base assembly and suggest an improved manufacturing method that uses frictional welding. The results will show that the new method of the frictional welding is better than the previous welding technique. Through the use of this concept of frictional welding, the welding conjunction will be strengthened, measurements will be more precise, and the cost and the number of processes will be reduced.