• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2001.05a
• /
• pp.186-195
• /
• 2001

The purpose of this study is to develop the time-dependent, one-dimensional numerical model on the interaction between irregular waves and two-layer permeable coastal structures, by extending and modifying the numerical model PBREAK(Wurjanto and Kobayashi, 1992) which is applicable only to one-layer permeable coastal structures. The two-layer permeable coastal structure consists of two permeable underlayers with different permeable media resting on an impermeable slope and an armor layer covering the permeable underlayer. The numerical model of this study simulates the wave over rough permeable underlayer of arbitrary geometry as well as the waves inside two-permeable underlayers of arbitrary thickness for specified normally-incident irregular waves. The utility of the numerical model is founded from comparing with PBREAK and the four hydraulic model tests under irregular waves. The sensitivities of computed results according to typical parameters(porosity, stone diameter, horizontal width of the permeable underlayer) and major factors(friction factor of primary armor layer etc.) discussed.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.12
• /
• pp.2827-2835
• /
• 2010

When the inferiorthreshold potential is applied on the membrane, the resting status membrane does not display any specific reaction, in the meanwhile if it receives somewhat higher voltages then it shows entirely different configuration. The fact that there is this kind of characteristics on the exciting membrane has been known for a long time, and some researchers have tried to analyze this situation using the electrical circuits but only limitted to inferiorthreshold potential case. The quantitative studies of especially for transthreshold stimulus is extremely rare up to now. The direct application of electrical circuit to biostatus is somewhat uneasonable because there may be much differences between them. We studied the electrical reaction quantitatively of biomembrane when it receives the transthreshold stimulus in point of electricity in this paper.

• Structural Engineering and Mechanics
• /
• v.44 no.4
• /
• pp.521-538
• /
• 2012

In this study, the transverse vibrations of an axially moving flexible beams resting on multiple supports are investigated. The time-dependent velocity is assumed to vary harmonically about a constant mean velocity. Simple-simple, fixed-fixed, simple-simple-simple and fixed-simple-fixed boundary conditions are considered. The equation of motion becomes independent from geometry and material properties and boundary conditions, since equation is expressed in terms of dimensionless quantities. Then the equation is obtained by assuming small flexural rigidity. For this case, the fourth order spatial derivative multiplies a small parameter; the mathematical model converts to a boundary layer type of problem. Perturbation techniques (The Method of Multiple Scales and The Method of Matched Asymptotic Expansions) are applied to the equation of motion to obtain approximate analytical solutions. Outer expansion solution is obtained by using MMS (The Method of Multiple Scales) and it is observed that this solution does not satisfy the boundary conditions for moment and incline. In order to eliminate this problem, inner solutions are obtained by employing a second expansion near the both ends of the flexible beam. Then the outer and the inner expansion solutions are combined to obtain composite solution which approximately satisfying all the boundary conditions. Effects of axial speed and flexural rigidity on first and second natural frequency of system are investigated. And obtained results are compared with older studies.

• Journal of the Korean Institute of Rural Architecture
• /
• v.6 no.3
• /
• pp.25-38
• /
• 2004

The government has made a great effort for the development of rural area. The aim of this study is to analyze the change process and characteristics of the government's rural area development policies implemented so far and present an aid as adequate material to the direction of development policy for rural areas. The rural area development policy had been focused on maintenance of physical infrastructure facilities in the rural areas, pursuing urban convenience led by the government from the 1950s to 1990s. The policy has changed to local residents-led rural area development from the late 1990s to present time. The basic direction of the policy turned into making much of environment-friendliness and promotion of regional activation. The policy was transformed to recognize our rural area and also perceive it pastoral and resting space. In addition, green tourism has emerged as an important theme since 2000. In the rural area development policy, it is the most important to connect it with various development projects, select target areas from the long-term perspective and pursue efficiency through intensified investment of financial resources.

• Earthquakes and Structures
• /
• v.18 no.6
• /
• pp.667-675
• /
• 2020

The current study compares the effect of structure-soil-structure interaction (SSSI) on the dynamic responses of adjacent buildings and isolated structures including soil-structure interaction (SSI) with the responses of fixed-base structures. Structural responses such as the relative acceleration, displacement, drift and shear force were considered under earthquake ground motion excitation. For this purpose, 5-, 10- and 15-story structures with 2-bay moment resisting frames resting on shallow foundations were modeled as a group of buildings in soft soil media. Viscous lateral boundaries and interface elements were applied to the soil model to simulate semi-infinite soil media, frictional contact and probable slip under seismic excitation. The direct method was employed for fully nonlinear time-history dynamic analysis in OpenSees using 3D finite element soil-structure models with different building positions. The results showed that the responses of the grouped structures were strongly influenced by the adjacent structures. The responses were as much as 4 times greater for drift and 2.3 times greater for shear force than the responses of fixed-base models.

• Structural Engineering and Mechanics
• /
• v.10 no.6
• /
• pp.517-532
• /
• 2000

A direct output feedback control scheme was recently proposed by the authors for single-story building structures resting on flexible soil body. In this paper, the control scheme is extended to mitigate the seismic responses of multi-story buildings. Soil-structure interaction is taken into account in two parts: input at the soil-structure interface/foundation and control algorithm. The former reflects the effect on ground motions and is monitored in real time with accelerometers at foundation. The latter includes the effect on the dynamic characteristics of structures, which is formulated by modifying the classical linear quadratic regulator based on the fundamental mode shape of the soil-structure system. Numerical result on the study of a $\frac{1}{4}$-scale three-story structure, supported by a viscoelastic half-space of soil mass, have demonstrated that the proposed algorithm is robust and very effective in suppressing the earthquake-induced vibration in building structures even supported on a flexible soil mass. Parametric studies are performed to understand how soil damping and flexibility affect the effectiveness of active tendon control. The selection of weighting matrix and effect of soil property uncertainty are investigated in detail for practical applications.

• Journal of Korean Medicine for Obesity Research
• /
• v.2 no.1
• /
• pp.73-82
• /
• 2002

Objectives: The purpose of this study is to investigate the effect of the aerobic exercise and weight training combined with VLCD(very low calorie diet) and chegameuyiin-tang(體減薏苡仁湯) on the change of the body composition during 15 days of hospitalization treatment. Methods: Twenty four female obese patients were observed. Exercise regimen was composed with aerobic exercise and weight training program, and the intensity of aerobic exercise were 50% HRmax(maximal heart rate) twice time a day and weight training were 50% 1RM(one repetition maximum) a day. All subjects diet regimen was VLCD of 600kcal/day. Results & Conclusions. 1. There was no significant difference between the aerobic exercise and the weight training groups in the change of body weight, fat mass, and percent body fat, waist-hip ratio, body mass index and resting metabolic rate. 2. In the comparison of the change rate of FFM(fat free mass), weight training group preserved FFM better than aerobic-exercise-only-group with no statistical significance.

• PNF and Movement
• /
• v.18 no.1
• /
• pp.87-95
• /
• 2020

Purpose: The purpose of this study was to investigate the effect of whole-body vibration training on the flexibility and agility of professional soccer players. Methods: Sixteen professional soccer players participated voluntarily in the study. Subjects were allocated to two groups: the experimental group received whole-body vibration (WBV) and team training, and the control group received only team training. Team training was conducted in 15 sessions of 70 min duration over 3 weeks. WBV training was applied at 40 Hz frequency, 5 sets (1 min-training, 1 min-resting) in a squatting position. Outcomes from sit-and-reach, side-step test, burpee test, and T-test were measured before and after training. To examine pre- and post-intervention differences between the two groups, a paired t-test was used. Independent t-tests were performed to compare pre- and post-test scores and the time difference of the two groups. Results: Significant improvements in sit-and-reach and agility variables were observed in the experimental group (p < 0.05). In particular, flexibility (sit-and-reach) and agility (the side-step test and the burpee test) were significantly different between the two groups (p < 0.05). Conclusion: These findings suggest that whole-body vibration training has a positive effect on performance enhancement for professional soccer players.

• Journal of the Korean Society of School Health
• /
• v.20 no.1
• /
• pp.45-52
• /
• 2007

Purpose: The purpose of this study was to examine the types of school accidents and their first aids at Elementary, Middle, High Schools in a local area. Methods: The subjects were 1062 students who have had episodes of school accidents from 730 (Elementary = 429, Middle = 188, High = 113) schools in Chungnam province from January to December, 2006. Data were collected from accident-related record from school nurse and 'School Safety Fund', and analyzed using the SPSS Version 13.0 programs and the results and conclusions are as follows: Results: The proportion of school accidents occurred were in middle(0.43%), high(0.35%), primary(0.30%) school students. And the most frequent type of accident was fracture and then sprain. Most school accidents broke out in playground during resting time, and followed by physical education class. The most frequent cause of school accidents was carelessness and first aid was fixation the injury. Conclusion: Based on these findings, school-based and continuous safety education programs and emergency care system within school and in community can be suggested in collaboration with health-related resources. Further longitudinal study to identify causes and kinds of school accidents and can also be recommended.

• Wind and Structures
• /
• v.32 no.5
• /
• pp.405-421
• /
• 2021

To gain insight into the wind-induced safety concerns associated with attached tower cranes during the construction of super-tall buildings, a 606 m level frame-core tube super-tall building is selected to investigate the wind-induced vibration response and fragility of an outer-attached tower crane at all stages of construction. The wind velocity time history samples are artificially generated and used to perform dynamic response analyses of the crane to observe the effects of wind velocity and wind direction under its working and non-working resting state. The adverse effects of the relative displacement response at different connection supports are also identified. The wind-resistant fragility curves of the crane are obtained by introducing the concept of incremental dynamic analysis. The results from the investigation indicate that a large relative displacement between the supports can substantially amplify the response of the crane at high levels. Such an effect becomes more serious when the lifting arm is perpendicular to the plane of the connection supports. The flexibility of super-tall buildings should be considered in the design of outer-attached tower cranes, especially for anchorage systems. Fragility analysis can be used to specify the maximum appropriate height of the tower crane for each performance level.