• Korean Journal of Applied Biomechanics
• /
• v.24 no.4
• /
• pp.349-357
• /
• 2014

The purpose of this study was to examine the differences in the performance of dancing motions depending on the level of skill by investigating pulmonary functions, ground reaction force, and jerk cost. The subjects of this study were 12 professional dancers (career: 16 yrs) and 12 amateur dancers (career: 9 yrs) who had similar physical conditions. We selected four motion phases which included the diagonal line motion, the deep flexion motion, the breath motion, and the turn motion with one leg after a small step walking motion, with Goodguri Jangdan. In the experiment, 6 infrared cameras were installed in order to analyze the value of the jerk costs and the force plate form. Finally, we measured the pulmonary functions of the subjects. For data analysis, independent t-tests according to each event, were carried out in the data processing. According to the results of FVC % Predicted, the professional dancers showed greater lung capacities than the amateur dancers, indicating that the level of dancing skill influences lung capacity. Based on the result of the balance test, the professional dancers used more vertical power than did the amateur dancers when performing maximal flexion motion. The professional dancers used a propulsive force of pushing their body forward by keeping the center of body higher while the amateur dancers used a braking power by keeping their bodies backward. When performing medial-lateral movements, the amateur dancers were less stable than the professional dancers. There were no differences in values of jerk costs between the amateur dancers and the professional dancers.

• Journal of the Korean Society of Industry Convergence
• /
• v.26 no.5
• /
• pp.915-923
• /
• 2023

As environmental regulations on carbon emissions are strengthened worldwide, the existing internal combustion engine-centered automobile industry is being reformed. In particular, large buses and large cargo trucks are pointed out as one of the main causes of environmental destruction due to excessive carbon emissions. The E-Highway power collection system, which has recently been proposed as a solution, uses the vehicle's battery as a backup power source or regenerative braking, depending on whether the pan head of the pentograph installed in the vehicle is in contact with the overhead line. It is used to store the excess energy generated. However, wear through contact due to continuous contact reduces the current collection effect and causes failure. In this paper, by using the current difference, the horizontal position information of the panhead in contact with the overhead line is acquired, thereby reducing the abrasion of the conductor and the panhead Make it possible to follow the overhead line. The position estimation method proposed in this paper simply configures a device that can detect the position of the overhead line of the pantograph by the difference in resistance. It is economical and has the advantage of reducing the volume. The characteristics of the pantograph estimating the location of overhead lines were analyzed using the difference between the two currents of the current collector, the feasibility of the positioning estimation system was verified through simulations and experiments.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.10
• /
• pp.483-489
• /
• 2018

Driving behaviors are reported to be vulnerable to safe driving in unexpected situations or driving in the city due to deterioration of physical and cognitive functions in elderly drivers. The purpose of this study was to investigate the difference in driving behaviors according to age of self-drivers and to identify changes in physical function related to driving caused by normal aging. The subjects of the study included 75 healthy adults (21 persons aged 20-39 years, 40 persons 40-64 years, 14 persons 65 years old) who were self-driving and possessed a driver's license. Data included sex, dominant hand, medication, exercise, age, and driving time obtained by a self-reported questionnaire. In addition, this study measured steering, acceleration and braking using a Driver Test Station. Results of the study showed there was no significant difference in power test according to age group, but the total time of the timer test and the emergency brake test significantly differed according to age. The timer test and emergency brake test were completed fastest in young adults between 20 and 39 years old and completed slowest in elderly people 65 years old or over. Based on our study results, it is suggested that normal aging affects the perceptual-cognitive processes associated with driving behaviors.

• Journal of the Korean Society for Railway
• /
• v.19 no.3
• /
• pp.314-323
• /
• 2016

Overhead line voltage of DC railway traction substations has rising or falling characteristics depending on the acceleration and regenerative braking of the subway train loads. The suppression of this irregular fluctuation of the line voltage gives rise to improved energy efficiency of both the railway substation and the trains. This paper presents parameter estimation schemes using the RC circuit model for an overhead line voltage at a 1500V DC electric railway traction substation. A linear artificial neural network with a back-propagation learning algorithm was trained using the measurement data for an overhead line voltage and four feeder currents. The least square estimation method was configured to implement batch processing of these measurement data. These estimation results have been presented and performance analysis has been achieved through raw data simulation.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.10
• /
• pp.1481-1486
• /
• 2013

The small wind generator with existing mechanical control system has a frequent failure and malfunction, and its maintenance is difficult. In this paper, an electric control method using a boost converter for small wind generator was suggested. The suggested 2-level boost converter control device was manufactured and its experimental operation were conducted on a wind generator with 200 [W] capacity. As a result of experimental device, the control by a boost converter was executed at the point that the output voltage of a wind generator became 36 [V] so it could be identified that the output voltage of a wind generator diminished and then it became 0 [V] after 5 [sec]. Besides, in case of applying the method suggested in this paper to a small wind power generation facility for street lights, it is expected to reduce its maintenance by preventing a frequent failure of a generator and to improve its utilization rate.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.32 no.3
• /
• pp.39-46
• /
• 1990

This paper was analized the thermal conductivity of polystylene (TENSAR- GEOGRID) embeding into the subbase through frost penetration depth, frost heave, change of bearing capacity, and soil moisture movement due to freezing, thawing and icing actions, and their results were as follows : 1.The change of temperature into the sub-base was much increased by the Tensar-Geogrid insertion, and the frost penetration and frost heave were decreased as the thinner of the insulation thickness but the thawing velocity of melting period was appeared to be faster in case of non-insulated. 2.The frost heave had a close relationship with the thickness of insulations which was reasonably included anti-frost effects. 3.The moisture content during the freezing period of upper layer of the insulation insertion was increased by 15 per cent but it was returned to initial state of the thawing period, and at the down layer temporarily increased by 10 per cent and returned to the original state at once. 4.The insulation was acted as a function of distribution of surcharge, and the settlement of the sub-base was about 1.5 mm under 15 tonnage of load and which was included within the allowable limits. 5.The sliding resistance due to the icing which was induced by the insulation insertion into the sub-base was appeared as more 40 per cent than noninsulation area, so that the insulations should be restricted on the place such as mountains, curved and cross area which were required the braking power under the traffics.

• Journal of Electrical Engineering and Technology
• /
• v.11 no.3
• /
• pp.609-617
• /
• 2016

Belt-driven Starter Generator (BSG) differs from other mild hybrid systems as the crankshaft of vehicle are not run off. Motor permits a low-cost method of adding mild hybrid capabilities such as start-stop, power assist, and mild levels of regenerative braking. Wound rotor synchronous motor (WRSM) could be adopted in BSG system for HEV e-Assisted application instead of the interior permanent magnet synchronous motor (IPMSM). In practice, adequate torque is indispensable for starter assist system, and energy conversion should be taken into account for the HEV or EV as well. Particularly, flux weakening control is possible to realize by adjusting both direct axis components of current and field current in WRSM. Accordingly, this paper present an off-line current acquisition algorithm that can reasonably combine the stator and field current to acquire the maximum torque, meanwhile the energy conversion is taken into consideration by losses. Besides, on account of inductance influence by non-uniform air gap around rotor, nonlinear inductances and armature flux linkage against current variation are proposed to guarantee the results closer to reality. A computer-aided method for proposed algorithm are present and results are given in form of the Look-up table (LUT). The experiment shows the validity of algorithm.

• Journal of Navigation and Port Research
• /
• v.34 no.10
• /
• pp.775-780
• /
• 2010

In the machinery, the brake system is as important part as machine's working. The situation of emergency stop, the machine doesn't stopped would be occur big accident. This is common things for all of machinery, also for the ships. There are two kind of mooring devices are existed on the ship. One of them, the windlass winch, is used to anchor. The other, the mooring winch is used to moor the ship in pier use the rope tied to bitt on dock. In case of previously been used mooring winch made of a steel plate, and the bolt which was connect brake band and lining broken. In this study, prevent an accident find the position of stress concentration by finite element analysis program. And removed stress concentration. And search the optimum position of the separation angle to be more efficient.

• Journal of Convergence for Information Technology
• /
• v.10 no.4
• /
• pp.160-167
• /
• 2020

This study analyzes the effects of changes in running velocity and slope on the biomechanical factors of the lower limb joints. For this purpose, 15 adult males in their 20s ran according to changes in running speed (2.7, 3.3 m/s) and slope ( -9°, -6°, 0°, 6°, 9°) on the treadmill, and their running characteristics (stride length, stride frequency). The range of motion of the lower limb joint and the vertical ground reaction force were greater in UR (p <.05), and the moment of the lower limb joint, braking force, thrust and load factor was large in DR (p <.05). In joint power, the ankle joint was greater in DR, and hip joint was greater in the UR (p <.05). These results show that the injuries of the ankle joint will be greater than other cases when running DR at a speed of 3.3 m/s.

• Journal of the Korea Safety Management & Science
• /
• v.15 no.1
• /
• pp.31-40
• /
• 2013

For the matter of elevator, one of the multi-use facilities for unspecified public, the JIS has re-established and reformed to apply to the environment in South Korea for the past 20 years. In the aspect of safety assurance, it was inevitable to suggest improved measures. The government, Ministry of Public Administration and Security has secured the safety by enhancing the safety management functions in the elevator inspection standards and expanding its safety device measures. Further, the international inspection standard has been introduced, which is about unifying inspection standard system into the international standard code. In March 14th 2012, the international standard (EN) has been amended and fully announced. Escalator and passenger conveyor among lift devices have several common danger factor that cause safety accident. First, the accident caused by decreased braking power of brake. Second, the accident caused by the rate difference between handrail and tread-board. Third, the accident caused by defects of contraflow preventing device or carelessness inspection. Fourth, the accident caused by wet tread-board or wet floor of platform which makes passenger slip and fall. As the improvements to prevent and reduce these negligent accidents, the inspection list to check and methods should be subdivided and applied for each accident likelihood cause for safety management enhancement and safety assurance of existing escalator and passenger conveyors. The escalators and passenger conveyors without safety devices in existence should be obliged to modify the part of the system or install additional safety device. With making these measures obligations, it requires to improve the system to be suitable for the international inspection standard and to have measures to prevent safety accidents. It also needs to arrange improvements for skid accident of tread-board by the external environment factors such as snow and rain.