• Korean Journal of Applied Biomechanics
• /
• v.18 no.1
• /
• pp.21-30
• /
• 2008

The purpose of this study was to investigate the variability to compare local dynamic stability via a linear and nonlinear analysis during walking. Twenty four elderly males, 12 healthy elderly and 12 patients with osteoarthritise walked on a treadmill for 100 consecutive strides. Lyapunov exponent and correlation dimension and coefficient variation were calculated for the kinematic parameters to determine the dynamic stability during walking. The linear measures indicated that the healthy elderly demonstrated significantly higher variability in the ankle joint displacement. The nonlinear analysis revealed that COD for the knee joint angle were higher in patient with osteoarthritise. There were no coincidence in results between linear and nonlinear techniques over two groups. In light of nonlinear analysis, it was concluded that patients with osteoathritise showed higher local instability during walking.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.05a
• /
• pp.430-435
• /
• 2005

조화가진력이 작용하는 고정경계를 가진 완전원판의 비선형 진동에 대한 응답특성을 연구하였다. 원판의 비대칭모드의 고유진동수 근처에 가진주파수가 작용하는 주공진에서의 응답은 정상파(standing wave)뿐만 아니라 진행파(traveling wave)가 존재한다고 알려져 있다. 주공진 근처의 정상상태 응답곡선에서 최대한 5개의 안정한 응답이 존재하는 것으로 밝혀졌으며, 이들은 1개의 정상파와 4개의 진행파로 나타난다. 이 진행파중 2개는 Hope분기에 의해 안정성을 잃은 후 주기배가운동을 거쳐 혼돈운동에 이르게 된다. Lyaponov 지수를 사용하여 혼돈운동을 정량적으로 평가하였으며, 주평면의 개념을 이용하여 이 혼돈운동의 흡인영역이 Fractal임을 확인하였다.

• 월간산업보건
• /
• s.387
• /
• pp.76-79
• /
• 2020

인체면적의 고작 2%를 차지하는 발바닥은 체중의 98%를 지탱하고 있습니다. 그래서인지 근골격계 질환 중에서도 손상이 빈번하게 일어나는 부위가 발목관절인데요. 스포츠 활동뿐만 아니라 일상생활 중에도 손상이 잘 일어나며 한번 손상되면 발목관절 안정성이 떨어지게 되어 재손상이 쉽게 발생합니다. 이에 발목관절 건강을 지킬 수 있는 적절한 예방운동이 꼭 필요합니다.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.22 no.7
• /
• pp.800-806
• /
• 2016

The maneuverability of a tugboat is affected by the slewing motion of a barge while the tug is navigating with the barge in water. Therefore, it is necessary to reduce the slewing motion of the barge to allow for safe towing work. In this study, a water tank experiment was performed to examine the factors affecting the slewing motion of a barge and improve course stability. The characteristics of slewing motion vary according to bow shape. Three barge models, each with a different bow shape, were selected as experimental subjects. A comprehensive analysis was performed to study the effects of various factors on the slewing motion of a barge such as the presence of a skeg and bridle, towing speed, and the length of the towline. The effect of the location of the skeg varied according to bow-hull form. The slewing motion of the barge decreased as the length of the towline increased, and this decrease was even greater when a bridle was connected to the towline. In addition, the slewing motion decreased significantly as the length of the bridle increased. The slewing angles did not show significant change with respect to towing speed.

• Proceedings of the ESK Conference
• /
• 1998.04a
• /
• pp.124-130
• /
• 1998

본 연구의 목적은 트레드밀 운동시 신체에 가해지는 중량별 부하가 심박수, 환기량, 호흡수, 이산화탄 소배출량, 산소섭취량, 체중당산소섭취량, 호흡교환률 등에 어떠한 영향을 미치는 지를 측정하여 훈련이 나 운동처방에 도움이 될 수 있는 자료를 얻고자 하였다. 피검자들은 성인 남녀 각 5명씩을 대상으로 하였으며, 신체 중량별 부하는 남자에게 안정시, 무부하, 5kg부하, 10kg부하, 15kg무하로 하였으며, 여자 에게는 안정시, 무부하, 5kg부하, 10kg부하로 구분하여 측정하였다. 운동부하는 트레드밀(TC-1200, Technogym, Italy)을 이용하여 중량별로 4km/hr로 3분간 실시하였다. 단계별 운동부하에 의한 인체에 미치는 호흡순환계의 변화를 조사하기 위해 호흡순환계의 변인을 측정 분석한 결과, 다음과 같은 결론 을 얻었다. 남자그룹의 경우는 심박수, 환기량, 이산화탄소배출량, 산소섭취량, 체중당산소섭취량, 호흡 교환률에 대한 중량별 평균차의 검증에서 안정시와 무부하, 5kg부하와 10kg부하, 10kg부하와 15kg부하 사이 에는 유의한 차이가 나타났고, 무부하와 5kg부하 사이에서는 유의한 차이가 없었다. 호흡수에있어서는 10kg 부하와 15kg부하 사이에서만 유의한 변화가 나타났다. 여자그룹의 경우는 심박수, 환기량, 이산화탄소배출 량에 대한 중량별 평균차의 검증에서는 안정시와 무부하, 무부하와 5kg부하, 5kg부하와 10kg부하 사이에서 유의한 변화가 나타났으며, 산소섭취량과 제중당산소섭취량에 있어서는 안정시와 무부하, 무부하와 5kg부하 사이네서만 유의한 변화가 나타났다. 또한 호흡교환률과 호흡수에 있어서는 안정시와 무부하 사이에서만 유의한 변화가 나타났으며, 무부하와 5kg부하, 5kg부하와 10kg부하 사이에는 유의한 차이가 없었다. 이와 같은 결과를 종합해 보면 남자에게는 걷기시에 단계별 무게부하가 호흡순환계에 영향을 미친다고 볼 수 있 으나, 5kg까지의 부하는 호흡순환계에 영향을 미치지 않고 일을 수행할 수 있음을 알 수 있다. 그리고 여자에게는 걷기시에 단계별 무게부하가 운동시 심박수와 환기량, 이산화탄소 배출량에는 영향을 미치고 호흡 교환률과 호흡수에는 영향을 미치지 않음으로보아, 여자에게는 걷기시에 단계별 무게 부하가 호흡순환계에 영향을 받고있음을 알 수 있다.

• Korean Journal of Applied Biomechanics
• /
• v.18 no.1
• /
• pp.203-212
• /
• 2008

The purpose of this study is to propose appropriate model for 3 staged Didimsae movement to Jajinmori rhythm and to provide information for ideal foot step movements. For the locational change of body center, the height of body center is lowered at the moment of forward step and during forward intersection of the feet, forward direction linear motion is converted to vertical motion to maintain stability. Speed change of body center reduces flow of body on step forward moment and controls rapid forward movement for stabled movement and position when preventing fast forward horizontal direction movement of centroid speed while knee joint and foot joint are vertically risen for heel bone contacts the ground. For angle changes of joints, in order to prevent hyperextension of lower leg, hip joint is extended and knee joint is curved to secure stability of movement for smooth curves and extension. When centroid of foot joint is moved from top of the feet to whole foot sole and when left foot makes dorsal curve, stabled movement is accomplished.

• Journal of Korean Society of Forest Science
• /
• v.103 no.3
• /
• pp.503-509
• /
• 2014

The purpose of this study was to investigate the effect of Forest-walking exercise on gait pattern in the elderly. The subjects (n=37) were assigned to 2 groups: Forest-walking exercise (FWE) group (n=19, $66.34{\pm}4.31$ years old) and In-door treadmill-walking exercise (ITWE) group (n=18, $67.18{\pm}2.78$ years old). The subjects participated in FWE program or ITWE program (3 times/week, 80 min/day) for 12 weeks. The subjects were tested on functional fitness (strength, endurance, agility/balance, BMI) and gait pattern (cadence, velocity, and stability) at the beginning and the end of the 12-weeks program. For data analysis, mean and standard deviation scores were calculated, and independent t-test and repeated two-way ANOVA were used. The results of this study were as follow: First, FWE group was significantly more improved than ITWE group on functional fitness(lower-body muscular strength, lower-body flexibility, mobility, cardiorespiratory endurance) after 12-weeks exercise program. But both groups showed equally improvements on functional fitness (upper-body muscular strength, upper-body flexibility, BMI). Second, FWE group was significantly more improved than ITWE group on cadence, gait velocity, and gait stability after 12-weeks exercise program. Therefore, this study may suggest that Forest-walking exercise based on sensory-motor functional integration improves efficiently functional fitness and gait pattern in the elderly, and further becomes an effective exercise method that makes more dynamic life, and prevents from falling.

• Korean Journal of Labor Studies
• /
• v.24 no.1
• /
• pp.29-64
• /
• 2018

This paper reviews the dynamics of growth and decline of Democratic Labor Union(Minju-nojo) Movement from the perspective of the conflicts among the industrial relations actors on the institutional incorporation of KCTU, a transformation of industrial relations institutes, and labor flexecurity in the change of political opportunity. The negotiations for the institutional incorporation of KCTU concluded in the 1997-98 labor laws. Since 1998, the conflicts and the compromises on the change of 1997-98 labor laws has continued. It was a kind of games for the transformation of the institutions of industrial relations and labor flexcurity. But the 1997-98 labor laws has shown the path-dependency. Since 2008, a cycle of the movement has entered a decline stage. The decline of Democratic Labor Union Movement came from the institutionalization of the movement, the change of political opportunity, and a generational change of 1987 cohorts group which has been the center of the movement.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.8 no.9
• /
• pp.1383-1389
• /
• 2013

This research was conducted to see the correlation between changes of ankle Joint Position Sense and Sway Area through Unstable Surface training. For the study, 48 healthy males and females were randomly divided into an unstable surface group(n=24) and a stable surface group(n=24). Then, they were asked to carry out the same exercise program three times a week for six weeks. The unstable surface group and stable surface group performed the exercise program on the balance exercise pad and on the hard ground, respectively. As a result, the unstable surface group displayed significantly reduced error of ankle joint position sense and sway area(p<.05). Moreover, a significant correlation between variances of ankle joint position sense and sway area was only found in the unstable surface group. In conclusion, this study demonstrated that there was a significant correlation between changes of ankle joint position sense and sway area through proprioceptive sense training on the unstable surface.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.16 no.2 s.107
• /
• pp.176-182
• /
• 2006

Modeling and verification for stability analysis of axially oscillating cantilever beams are investigated in this paper Equations of motion for the axially oscillating beams are derived and transformed into dimensionless forms. The equations include harmonically oscillating parameters which are related to the motion-induced stiffness variation. stability diagram is obtained by using the multiple scale perturbation method. To verify the accuracy of the modeling method, several points in the plane of the stability diagram are presented and solved. The present modeling method proves to be as accurate as a nonlinear finite element modeling method.