• Journal of the Korean Applied Science and Technology
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• v.37 no.6
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• pp.1728-1737
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• 2020

The purpose of this study was to verify the effects of the types of exercise on the health-related fitness among the elderly women, and to provide the information for managing and preventing the chronic disease. 40 elderly women who living in the B metropolitan city participated in the study and randomly divided four groups(control, aerobic exercise, resistance exercise, and combined exercise). The exercise groups performed 50 min, 3 times/week for 8 weeks at RPE 11-13. Low body strength, dynamic balance, static balance, and agility were significantly improved in all exercise groups after the intervention. Cardiovascular endurance was improved in aerobic and combined exercise groups. Consequently, any types of exercise could be improved the daily living fitness for elderly women if exercise intensity were the same. In addition, the combined exercise may be more suitable type of exercise for elderly.

• Journal of the Korean GEO-environmental Society
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• v.24 no.10
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• pp.51-58
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• 2023

The dynamic behavior of the group piles supporting the superstructure in an earthquake is influenced by different complex dynamic mechanisms by the inertia force of the superstructure and the kinematic force of the ground. In an earthquake, The dynamic p-y curve is used to analyze the dynamic behavior of the pile foundation in consideration of the interaction of the ground, pile foundation, and superstructure due to the inertia force and the kinematic force. Most of the research has been conducted in order to confirm the dynamic p-y curve of the pile foundation by applying to the pile foundation installed on the single layered ground consisting of sand and clay, but the research for the multiple layered ground is insufficient. In this study, 1g shaking table tests were conducted to analyze the effect of the strata ratio of the top and bottom ground of the two layered sandy ground which has different relative densities on the dynamic behavior of group piles supporting the superstructure. The result shows that the maximum acceleration in the ground, the pile cap, and the superstructure increases as the strata ratio increases, and the location of the maximum bending moment of the pile foundation is changed. In addition, it was confirmed that the slope of the dynamic p-y curve of the pile foundation increased and decreased according to the strata ratio.

• Journal of the Korea Convergence Society
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• v.9 no.4
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• pp.261-269
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• 2018

The purpose of this study was to determined the converge effects of Kaatsu treatment on body compositions, physical fitness and dynamic and static balance during unmilled rice dumbbell exercise in older women. They are divided into three groups(Kaatsu treatment+exercise, n=12, non-Kaatsu treatment+exercise, n=11, Control, n=12). In this study, there were a no significant differences on body weight and lean body mass and body mass index between the group, but there was a significant differences on percent of body fat between the group(P<.001). There was a significant differences on left grip strength between the group, and significant differences on flexibility and agility after the unmilled rice dumbbell exercise training. There were a significant differences on the dynamic and static balance between the group after the unmilled rice dumbbell exercise training(respectively P<.001, P<.05).

• Journal of Korean Association for Spatial Structures
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• v.4 no.2 s.12
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• pp.81-88
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• 2004

The dynamic instability of snapping phenomena has been studied by many researchers. Few papers deal with dynamic buckling under loads with periodic characteristics, and the behavior under periodic excitations is expected to be different from behavior under STEP excitations. We investigate the fundamental mechanisms of the dynamic instability when the sinusoidally shaped arch structures are subjected to sinusoidally distributed excitations with pin-ends. The mechanisms of dynamic indirect snapping of shallow arches are especially investigated under not only STEP function excitations but also under sinusoidal harmonic excitations, applied i the up-and-down direction. The dynamic nonlinear responses are obtained by the numerical integration of the geometrically nonlinear equation of motion. And using this analyze characteristics of the dynamic instability through the running response spectrum by FFT(Fast Fourier Transform).

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.714-717
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• 2011

본 논문에서는 선체 블록의 운반 작업 중 발생하는 동적 하중 및 골리앗 크레인의 와이어로프와 선체블록 간의 동적 접촉력을 고려한 최적 러그 배치 시스템을 설계하고, 다물체계 동역학 커널과 외력 계산커널을 개발하였다. 다물체계 동역학 커널은 recursive formulation을 이용하여 운동 방정식을 구성하고, 외력 계산 커널은 비선형 유체정역학적 힘, 선형 유체동역학적 힘, 풍력, 계류력을 계산할 수 있다. 이를 이용해 블록에 작용하는 와이어로프와 블록 간의 간섭과 동적 접촉력을 계산하고, 그 결과를 이용하여 러그가 부착된 블록의 구조 해석을 수행하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.1
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• pp.73-82
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• 1983

초기결함을 가진 직교이방성원통셸이 축방향스텝하중을 받은 때의 동적좌굴을 연구하였다. 원통 쉘의 운동방정식은 비선형 Donnell 방정식을 사용하였으며 변위식에는 6개항을 채용하였다. 좌굴 조건은 원통셸의 수직변위와 길이변화의 급격한 변화로써 정의하였다. 좌굴모우드형상은 초기결 함과 쉘재료의 이방성에 따라 달라짐은 발견하였고 좌굴강도는 초기결함의 증가에 따라 크게 감 소된다.

• Journal of Advanced Marine Engineering and Technology
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• v.11 no.2
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• pp.61-70
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• 1987

미지의 조작량이나 매우 큰 외란이 입력으로 작용하고 있는 동력시스템의 정도 높은 상태를 추정하려면 상태추정에 앞서 시스템의 입력추정이 요구된다. 본 논문에서는 간략형 칼만필터 (SKF:Simplified Kalman Filter)를 이용하여 운동하고 있는 목표물의 상태추정을 행함과 동시에 기동탐지자 (Maneuvering Detector)와 입력추정자 (Input Estimator)에 의해 시스템의 입력을 추정하고 이것에 의하여 SKF의 추정치를 보정해줌으로써 입력이 미지인 동적 시스템의 상태추정에 있어서 추정정도를 개선하는 방법을 제안하며 디지탈계산기를 이용한 시뮤레이션을 통하여 본 방법의 유효성을 밝힌다.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.142-144
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• 2003

3차원 apparel CAD system개발에 있어서 직물의 드레이프 모사가 걸림돌이 되어왔다. 최근 컴퓨터의 속도 개선으로 인해 정적 드레이프의 경우 데이블 보 문제와 같이 적절한 시간내에 드레이프 모사가 이루어지고 있다. 그러나 드레이프는 cloth와 body간의 충돌 검사에 많은 시간이 소요되므로 virtual fashion show와 같이 인체가 운동하는 동적 드레이프의 경우는 아직도 어려운 문제이다. (중략)

• 한국노년학
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• v.29 no.4
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• pp.1261-1275
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• 2009

Age related decrease of muscle strength, balance, and gait abilities bring about physical inactivity in the elderly. Virtual reality (VR) training has been used successfully to rehabilitate functional balance and mobility in elderly subjects. This study was aimed at determining the effect of VR-based exercise programs by using a video game on the muscle strength, balance, and gait abilities in the elderly. 48 old people were randomly divided into two groups; VR-group (men: 11, women: 14, age: 68.42yrs) and control group (men: 10, women: 13, age: 67.58yrs). VR-group performed an exercise program twice a week for 8 weeks and control group had no intervention. The VR-based exercise program was composed of warm up(10 mins), VR-program(40 mins), and cool down(10mins). It was performed by playstation eyetoy play that provided visual and auditory feedback as well as movements of the upper and lower extremities. Muscle strengths of the knee and ankle were measured using manual muscle tester. Static balance was estimated using computerized posturography. Dynamic balance was measured by Timed up and go test (TUG), Functional reach test (FRT). 10m walk test and 6-min walk test were used to assess gait abilities. After the completion of the VR-exercise program, muscle strength, balance, and gait abilities were improved significantly (p<0.05). In conclusion, the VR-based exercise program showed improvement on the muscle strength, balance, and gait ability in the elderly. This exercise program is both effective and interesting for this age group.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.140-145
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• 2018

This paper deals with the dynamical analysis of a two-point mooring vessel under surge excitations. The characteristics of nonlinear behaviors are investigated completely including bifurcation and limit cycle according to particular input parameter changes. The strong nonlinearity of the mooring system is mainly caused by linear and cubic terms of restoring force. The numerical simulation is performed based on the fourth order Runge-Kutta algorithm. The bifurcation diagram and several instability phenomena are observed clearly by varying amplitudes as well as frequencies of surge excitations. Stable periodic solutions, called the periodic windows, can be obtained in succession between chaotic clouds of dots in case of frequency ${\omega}=0.4rad/s$. In addition, the chaotic region is unexpectedly increased when external forcing amplitude exceeds 1.0 with the angular frequency of ${\omega}=0.7rad/s$. Compared to the cases for ${\omega}=0.4$, 0.7rad/s, the region of chaotic behavior becomes more fragile than in the case of ${\omega}=1.0rad/s$. Finally, various types of steady states including sub-harmonic motion, limit cycle, and symmetry breaking phenomenon are observed in the two-point mooring system at each parameter value.