• Wind and Structures
• /
• v.23 no.1
• /
• pp.19-43
• /
• 2016

In the present study, a new methodology is presented to study the ride comfort and bridge responses of a long-span bridge-traffic-wind coupled vibration system considering stochastic characteristics of traffic flow and bridge surface progressive deterioration. A three-dimensional vehicle model with 24 degrees-of-freedoms (DOFs) including a three-dimensional non-linear suspension seat model and the longitudinal vibration of the vehicle is firstly presented to study the ride comfort. An improved cellular automaton (CA) model considering the influence of the next-nearest neighbor vehicles and a progressive deterioration model for bridge surface roughness are firstly introduced. Based on the equivalent dynamic vehicle model approach, the bridge-traffic-wind coupled equations are established by combining the equations of motion of both the bridge and vehicles in traffic using the displacement relationship and interaction force relationship at the patch contact. The numerical simulations show that the proposed method can simulate rationally the ride comfort and bridge responses of the bridge-traffic-wind coupled system; and the vertical, lateral, and longitudinal vibrations of the driver seat model can affect significantly the driver's comfort, as expected.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.20 no.7
• /
• pp.629-636
• /
• 2010

A Mobile Harbor is a new transportation platform which can load and unload has containers to and from very large container ships on the sea. Currently designed Mobile Harbor a catamaran type which is equipped with precisely controlled gantry crane on the deck, and can transport 250 TEUs at a time. Loading and unloading works by crane require very small motion of Mobile Harbor in waves, because it may be operated outside of harbors. In this project, applicability of both tuned-type anti-rolling tank and maglev-type active mass driver is studied as anti-rolling systems.

• Journal of the Korean Society for Precision Engineering
• /
• v.14 no.5
• /
• pp.118-127
• /
• 1997

In this study, We use microstep control to reduce vibration of step motor. Microstep control of step motor is usually thought of as an extension of conventional step motor control technology. The essence of micro stepping is that we divide the full step of a step motor into a number of substep called microstep and cause the stepmotor to move through a substep per input pulse. In ideal case, by controlling the individual phase currents of a two-phase step motor sinusoidally we can get uniform torque and step angle. But due to the nonlinear characteristics of the step motor, we need to compensate current waveform to improve the over-all smoothness of the conventional micro stepping system. We implement digital Pulse Width Modul- ation (PWM) driver to drive step motor and microphone was used for detecting vibration. Driver enables speed change automatically by increasing or decreasing micro stepping ratio which we call Automatic Switching on the Fly. To compensate the torque harmonics, neural network is applied to the system and we found compensated optimal input current waveform. Finally we can get smooth motion of step motor in a wide range of motor speed.

• Korean Journal of Applied Biomechanics
• /
• v.34 no.1
• /
• pp.1-8
• /
• 2024

Objective: The aim of this study was to identify the biomechanical determination factor for improving club head speed during the driver swing in male golf players. Method: Twenty-seven golf players were participated in this study. Eight motion capture cameras (250 Hz) and two force plates (2,000 Hz) were used to collect peak angular velocity and ground reaction force data. It was performed stepwise multiple linear regression analysis and alpha set at .05. Results: The peak plantar flexion angular velocity of the left ankle joint and the peak adduction angular velocity of the right shoulder joint were statistically significant. The peak plantar flexion angular velocity of the left ankle joint and the peak adduction angular velocity of the right shoulder during downswing. Conclusion: It is suggested that applying body conditioning training aimed at improving related body functions to increase maximum plantar flexion angular velocity in the left ankle joint will be effective in improving club head speed.

• Korean Journal of Applied Biomechanics
• /
• v.26 no.3
• /
• pp.265-272
• /
• 2016

Objective: The aim of this study was to analyze X-factor, triple X-factor, and the center of pressure (COP) according to the feel of golf driver swing. Method: For this research, 9 golfers from the Korea Professional Golfers' Association (age: $30.11{\pm}2.98yrs$, height: $178.00{\pm}8.42cm$, weight: $76.22{\pm}8.42kg$, experience: $10.06{\pm}3.11yrs$) were recruited to participate in the experiment. Twelve Motion Analysis Eagle-4 cameras were installed and an image analysis was conducted by using the NLT (non-linear transformation) method, and 2 units of Kistler type 5233A dynamometer were used to measure ground reaction force. The sampling ratio was set at 1000 Hz. The golfers each took 10 swings by using their own driver, and chose the best and worse feel from among 10 shots. A paired-sample t-test was used to analyze the results. Results: In regard to feel, no change in head speed, X-factor, and the triple X-factor's X-factor stretch, hip rise, and head swivel, was observed (p>.05). Regarding ground reaction force, a difference was observed between the top of the backswing (p<.05) and impact (p<.05) in the vertical force of the left foot. For COP, a difference was also observed between the mid backswing (p<.001), late backswing (p<.001), and top of the backswing (p<.05) for the right foot X-axis and Y-axis mid follow through (p<.01). Conclusion: It can be reasoned that, irrespective of feel, the head speed, X-factor and triple X-factor's X-factor stretch, hip rise and head swivel did not have an effect on drive distance for domestic golfers, and the vertical reaction force of the left foot and left-right movement span's pressure dispersal of the right foot had an increasing effect on drive distance.

• Journal of the Korea Society of Computer and Information
• /
• v.26 no.11
• /
• pp.191-199
• /
• 2021

This study aims to present the need to supplement the driver's license renewal test for elderly drivers. In Korea, the proportion of elderly drivers is increasing as the elderly population increases rapidly. Overall the traffic accident rate is decreasing but the traffic accident and death rate from traffic accidents are increasing in older drivers. In this study the assessments and education conducted when renewing the driver's license for elderly drivers conducted in Korea were conducted to find out the necessary tests compared to the current situation of foreign countries. Although it is appropriate to evaluate the three key functional areas of vision, cognition, motor and somatosensory, we currently evaluate visual acurity in vison area. While MMSE-K and Clock drawing tests are not recognizable for mild cognitive impairment in cognitive areas. The motor and somato sensory function to perform driving are not evaluated at all. Therefore for safe driving of older drivers, the test to be conducted during renewal of the driver's license will need to supplement that the visual field and contrast sensitivity in vision area, cognitive function from mild cognitive impairments, and the endurance, functional range of motion and proprioception in motor function area.

• Journal of the Korean Applied Science and Technology
• /
• v.38 no.1
• /
• pp.1-8
• /
• 2021

The purpose of this study was to analyze relationship between biomechancal factors and diver's distance during golf driver swing. Fifteen professional golfers were participated in as subject. Eight motion capture cameras(250 Hz), 2 force plates(1000 Hz), and Trackman were used to collect kinematic and kinetic datas. It was performed Pearson's correlation analysis using SPSS 24.0. The level of significance was at .05. Ball speed, club head speed, X-Factor, and ground reaction force were correlated on driving distance, However, smash factor and knee moment were not correlated on driving distnace. Ball speed, club head speed, X-Factor, and ground reaction force were effected to driving distance, but smash factor and knee moment were not effected to driving distance.

• Journal of Korean Society of Transportation
• /
• v.21 no.2
• /
• pp.7-16
• /
• 2003

To minimize the death and injury by a collision, the installation of an air bag is recommended as a mandatory practice together with the wearing of the seat belt. By using simulated collision experiments, this research focused on the effect of an air bag and seat belt on the driver safety. The vehicle deceleration characteristics were obtained from impact experiment. LSDYNA, a software program for vehicle collision analysis, and MADYMO. a software program for driver motion after collision, were used for simulated experiment. Four cases such as air bag installed and seat belt wearing (case A), air bag installed but seat belt not wearing (case B), air bag not installed but seat belt wearing (case C), air bag not installed and seat belt not wearing (case D) were analyzed. The impact of acceleration on the injury of driver's head was analyzed by Head Injury Criterion (HIC) as well. It was found that having air bag and wearing seat belt effectively reduced driver's head injury about 52.9% to 70.5% compared with the case of having neither air bag nor wearing seat belt.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.40 no.5
• /
• pp.525-530
• /
• 2016

In this paper, we proposed an image shaking index to evaluate the remote controllability of vision based unmanned vehicles. To analyze the usefulness of the proposed image-shaking index, we perform subjective tests using a virtual unmanned vehicle driving simulator. The developed driving simulator consists of a real-time multibody dynamic software of the unmanned vehicle, a motion simulator, and a driver console. We perform dynamic simulations to obtain the motion of the unmanned vehicle running on the various road surfaces such as ISO roughness level A~E roads. The motion of the vehicle body is reflected in the motion simulator. Then, to enable remote control operation, we offer to operators the image data that was measured using the camera sensor on the simulator. We verify the usefulness of the proposed image-shaking index compared with subjective index provided by operators.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.14 no.1
• /
• pp.8-14
• /
• 2009

A lamp which is currently employed to LCD(Liquid Crystal Display) Backlight is almost CCFL(Cold Cathod Fluorescent Lamp) and EEFL(External Electrode Fluorescent Lamp). However, the use of these lamps is being restricted as RoHS(the Restriction of the use of certain Hazardous Substances in electrical and electronic equipment) regulation is gradually reinforced. According to this situation, the manufacturing of a lamp which doesn't use mercury is unescapable. Moreover, LCD TV has a defect which take place Motion Blur phenomenon due to response time of LC(Liquid Crystal), and Hold-type characteristic which only exists in LCD differently to CRT, PDP. In this paper, an inverter is proposed to drive a plane light source lamp which is not containing mercury. Driving circuit of proposed inverter is simple because the number of semiconductor device and magnetic device is reduced by using forward topology. Also, Motion Blur phenomenon is decreased by dividing the plane light source lamp to six block along vertical direction, and scanning. Finally, we proved usefulness of proposed inverter through experiment.