• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.18 no.4 s.70
• /
• pp.361-372
• /
• 2005

In the previous study(Kim 등, 2004), the finite element method was used for the vortical vibration analysis of suspension bridge with the effects of the shear deformation and the rotary inertia under moving load considering the bridge-vehicle interaction. The purpose of this study is to investigate the effect of an eccentric vehicle and shear deformation. So we firstly performs the eigenvalue analysis for the free vortical and the torsional vibration of suspension bridges using FEM analysis. Next the equations of motion considering interaction between suspension bridges and vehicles/trains are derived using the mode superposition method. And then dynamic analysis was performed using the Newmark method. Finally through the numerical examples, the dynamic responses of bridges are investigated according to the proposed procedure.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.10 no.3 s.49
• /
• pp.1-11
• /
• 2006

This paper presents a seismic fragility analysis method for a cable-stayed bridge with energy dissipation devices. Model uncertainties represented by random variables include input ground motions, characteristics of energy dissipation devices and the stiffness of cable-stayed bridge. Using linear regression, we established demand models for the fragility analysis from the relationship between maximum responses and the intensity of input ground motions. For capacity models, we considered the moment and shear force of the main tower, longitudinal displacement of the girder, deviation of the stay cables tension and the local buckling of the main steel tower as the limit states for cable-stayed bridge. As a numerical example, fragility analysis results for the 2nd Jindo bridge are presented. The effect of energy dissipation devices is also briefly discussed.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.5
• /
• pp.924-932
• /
• 1992

This paper presents the results of an experimental study on the characteristics of the vortex- induced vibration of an elastically supported circular cylinder in the cross air flow. For a range of velocities, power spectral densities of the signals from a hot-wire anemometer placed in the wake of an oscillating circular cylinder and gap sensors placed in the both ends of a circular cylinder were obtained to determine vortex-shedding frequencies, natural frequencies and vibrating frequencies of a cylinder. The effects of slots in the test section on vortex shedding and cylinder oscillation were investigated. The present study covered the reduced velocity range 1.0 .leg. Ur .leg. 64.6. The response characteristics of the cylinder has been shown to vary extensively, depending on the slots in the test section as well as on the reduced velocity. For an elastically supported cylinder, a purely translation mode oscillation was observed at a low velocity, however a rotation mode oscillation was often superposed for higher velocities. These two oscillating frequencies were equal to their natural frequencies irrespective of the changes of free stream velocities.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.11 no.6
• /
• pp.33-39
• /
• 2007

The seismic source parameters of the Uljin earthquake on 29 May 2004, including focal depth, focal mechanism, magnitude, and moment tensor elements for source characteristics, are analysed using moment tensor seismic source inversion. The Green‘s function for 3 crust models representing the southern Korean Peninsula are used. Also 3 kinds of epicenters are used to find optimum solution for seismic source parameters. Results show that seismic source parameters have a little dependency of azimuthal distribution and epicentral distances of seismic stations. Final results show that the event, considering 6 moment tensor elements, is caused by the typical reverse fault with nearly NS strike. The focal mechanism implies that the tectonic force around epicenter area currently has compressive environment, with nearly EW principal axis. The focal depth is estimated to be about 12km. The resultant focal mechanism show fairly good agreement to those of other studies. However, focal depth is much different from that of other studies.

• Journal of Navigation and Port Research
• /
• v.43 no.6
• /
• pp.403-412
• /
• 2019

The characteristics of the manoeuvring motion of a ship are dependent on the ship type, as well as draft or speed in the same ship. In recent years, the number of extra-large vessels has increased significantly, which can cause enormous material and environmental damage in the event of a marine accident. Thus, the importance of ship maneuvering is increasing. The IMO has forced the officers to be trained in simulators through the STCW 95 amendment. However, FMSS is costly and difficult to access and the PC-based simulator has the disadvantage that only one person can engage in simulation. The purpose of this study was to solve the shortcomings of the FMSS and PC-based simulators by enabling multiple people to use their PCs to simulate based on a network. The simulator is implemented through the analysis and numerical calculation of the Nomoto model, Radar function mounting, data transfer protocol design, and GUI building. To verify the simulator, the simulation results were compared and analyzed with the test results of T.S. HANBADA according to the criteria of the Korean Register of Shipping(KR) and IMO standards for ship maneuverability. As a result, It showed a relative error of 0%~ 32.1% with an average of 13.7%, and it satisfied the IMO criteria for ship maneuverability.

• Journal of the Korean earth science society
• /
• v.32 no.1
• /
• pp.1-11
• /
• 2011

The impact echo and impulse response methods were applied to the safety inspection of concrete structure, which has the rear cavity. The concrete structure model used in this study was divided into four sections, pure concrete, concrete+cavity, reinforced concrete with iron bar, and reinforced concrete+cavity, respectively. Previous study performed by authors have showed a possibility of success to use these method for detection of the rear cavity of concrete structure. Therefore, we tried to get more enhanced result with IE and IR methods through this study. Especially, IE and IR methods are relatively accurate to map the point of measurement, which makes it possible to interpret the depth of the concrete bed and effect by rear cavity with confidence. Followings were revealed from the results; the IE method shows some small peak zones probably indicating the rear cavity in the frequency lower than the resonance frequency and the changes of mobility and dynamic stiffness in the IR method indicate the weak zones. The proposed methods can be used to delineate the weak zones of the concrete structure.

• Journal of the Korea Convergence Society
• /
• v.13 no.5
• /
• pp.295-305
• /
• 2022

This study aimed to present a realistic policy direction to reduce human rights violations by analyzing the mechanisms of its factors affecting the experience of human rights violations for middle and high school student athletes. The method analyzed the response data of 13,205 student athletes through a structured questionnaire using logistic regression analysis. The independent variable consisted of sexual violence, sexual shame, physical violence, verbal violence, bullying, invasion of privacy and learning rights, and unfair leaders' actions related to exercise. As a result of the analysis, first, the team atmosphere, human rights consciousness in their sports and in the sports field were found to have a significant influence on physical and language violence, bullying, privacy and infringement of learning rights. Second, for the experience of sexual violence, the team atmosphere and the level of awareness of human rights violations in the sports community had a significant effect, but the permission of violence in the sports community and human rights consciousness in their sports did not appear as meaningful variables. Third, it was found that the unfair experience related to exercise had a significant effect on the team atmosphere, the overall level of violence in the sports community, and the its awareness of human rights violations in the sports community.

• Journal of the Korean earth science society
• /
• v.33 no.2
• /
• pp.170-182
• /
• 2012

The purpose of this study was to develop learning materials based on the Kepler's abductive reasoning and to identify high school students' rule-inferring strategies on the law of planetary motion. The learning materials including the concepts of solar magnetic field, conservation of figure skater's angular momentum and Kepler's polyhedral theory were developed and the questions about Kepler's 2nd and 3rd law of planetary motion were also created. The participants were 79science high school students and 83general high school students. The patterns and properties of their abductive inference were analyzed. The findings revealed that the students showed 'incomplete analogy abduction', 'analogy abduction' and 'reconstruction' to generate the hypotheses concerning the Mars' motion related to the solar magnetic field. There were more general high school students who showed the incomplete analogy abduction than science high school students. On the other hand, there were more science high school students who showed the analogy abduction and reconstruction strategy than general high school students. Also, they showed 'incomplete analogy abduction', 'analogy abduction' and 'model construction and manipulation' to generate the hypotheses concerning Kepler's second law. A number of general high school students showed the incomplete analogy. It is suggested that because the analogy of figure skater cause the students' alternative framework to use, more detailed demonstration is necessary in class. In addition, students combined Kepler's polyhedral theory with their prior knowledge to infer Kepler's third law.

• 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 Institute of Landscape Architecture
• /
• v.50 no.4
• /
• pp.53-62
• /
• 2022

Animal companionship is gaining popularity in Korea, and interest in dog walking is also increasing as a strategy to maintain the physical and mental health of dogs and dog owners. The purpose of this study was to investigate the perception and satisfaction of dog owners with the neighborhood environments for dog walking and to examine the willingness to pay (WTP) for an off-leash dog park. Of a total of 249 online survey respondents, 47.8% said they take a walk at least once a day and mainly walk around nearby neighborhoods or parks. Respondents showed a high attachment to their dogs and recognized that dog walks help increase physical activity and maintain the health of owners and their dogs. The satisfaction with neighborhood environments, such as attractive views and the connection of walking trails, was low, and there was a high demand for off-leash dog parks. The truncated mean WTP was estimated to be 85,618 Korean Won, and the result of regression analysis and t-test revealed that walking frequency and the satisfaction with dog walking facilities were statistically significant in the WTP. In order to encourage dog walking to promote physical activity and health, more attention needs to be devoted to improving neighborhood environments for dog walking.