• 한국운동역학회지
• /
• 제30권1호
• /
• pp.73-81
• /
• 2020

Objective: The purpose of this study is to analyze the effects of aquatic walking exercise on gait and balance parameters of elderly women. Method: 15 elderly people were recruited for this study (age: 73.20±5.19 yrs, height: 153.87±3.36 cm, mass: 60.33±5.73 kg). All variables were measured using Gaitview AFA-50. The variables were the heel contact time ratio, gait angle, and M/P change ratio for gait patterns and ENV, REC, RMS, Total Length, TLC, Sway velocity, and Length/ENV for balance abilities. A paired t-test and the Wilcoxon signed-rank test were carried out to verify the differences in the test scores after participating in the water walking program. The significance level for all statistical analyses was set to α=.05. Results: As for the changes in their walking function after the exercise, heel contact time ratio (p<.01) showed a statistical significance, while gait angle and M/P change ratio did not reveal statistically significant differences. In the test of balance ability on both feet and with eyes opened, statistical significance was found in ENV, REC, RMS, TLC (p<.01), and sway velocity (p<.05), while the test with eyes closed showed statistical significance in length/ENV as well as ENV, REC, RMS, sway velocity (p<.01) TLC, and total length (p<.05). As for the single-leg stance balance ability, ENV and REC revealed statistically significant differences. Conclusion: These results show that water walking is effective for improving the function of the ankle flexor muscles, providing stability to the ankle joint during walking and helping efficient walk. In addition, it is also expected to help prevent falls due to loss of balance by improving the stability of lower extremity muscles and trunk.

• 한국운동역학회지
• /
• 제26권3호
• /
• pp.293-301
• /
• 2016

Objective: The purpose of this study was to analyze the effects of freezing of gait and visual information on the static postural control ability in patients with Parkinson's Disease (PD) during the bipedal stance with feet together. Method: This study included a total of 36 patients with PD; the freezer group included 17 PD patients (age: $69.3{\pm}6.2yrs$, height: $159.6{\pm}9.0cm$, weight: $63.4{\pm}9.78kg$) and the nonfreezer group included 19 PD patients (age: $71.4{\pm}5.6yrs$, height: $155.8{\pm}7.1cm$, weight: $57.7{\pm}8.6kg$). Static postural control ability was analyzed using variables of center of pressure (COP) and dividing by mediolateral, anteroposterior, and integration factors during a bipedal stance with the eyes open and closed. Results: Freezers and nonfreezers showed increases in anteroposterior velocity, mediolateral velocity, averaged velocity, and mediolateral 95% edge frequency when visual information was blocked. Additionally, freezers had greater anteroposterior range, 95% confidence ellipse area, and COP anteroposterior mean position than nonfreezers. Conclusion: Freezers and nonfreezers showed a reduction in static postural control ability when visual information was blocked. Additionally, the results of this study found a significant difference in static postural control ability between freezers and nonfreezers with PD. In particular, anteroposterior range, 95% confidence ellipse area, and COP anteroposterior mean position might be used to distinguish between freezers and nonfreezers with PD.

• 한국운동역학회지
• /
• 제16권2호
• /
• pp.75-83
• /
• 2006

The Purpose of this study was to compare the biomechanical difference of two soccer footwear. which will provide scientific data to coaches and players, to further prevent injuries and to improve each players skills. The result of this study can be summarized after testing the two types of soccer footwear with comparative transforming heel angles and also with a pressure distribution in running. When a player's foot first touched the ground, the average difference of in/eversion was between 1.2 and 3.1 degrees for the two soccer shoes. In regards to maximum inversion and eversion of foot, maximum tibial rotation, and maximum and total movement of foot, the condition of barefoot and the two soccer shoes showed a small difference from 1.5 to 3.5 degrees and the difference among the subjects of study wasn't constant. In regards to maximum velocity of inversion and eversion running in one's bare feet showed much lower inversion velocity in comparison to putting on two types of soccer shoes and comparison of the average. Among some of the subjects, after putting on the two types of soccer shoes exceeded $97^{\circ}/s$ in maximum velocity of eversion. In the maximum braking impulse(t=2774, p<.05) and propulsive impulse for antero-posterior direction, there was a statistically significant difference between the two soccer footwear at running. In the maximum braking force(t=3.270, p<.05) and propulsive force(t=4.956, p<.05) for antero-posterior direction, there was a statistically significant difference between the two soccer footwear at running.

• 한국응용과학기술학회지
• /
• 제40권5호
• /
• pp.977-987
• /
• 2023

본 연구의 목적은 시각정보로 양안시와 단안시 사용 시 Y-Balance Test(YBT) 수행이 YBT 절대도달거리, 수행점수와 압력중심 변인을 통하여 동적균형에 미치는 영향을 알아보고자 하였다. 연구의 대상자로 20-30대 성인 18명(연령: 23.17±1.72 년, 신장: 172.46±9.84 cm, 체중: 73.39±11.44 kg 다리길이: 88.89±5.69 cm)이 연구에 참여하였다. 양안 및 단안 사용으로 동적 균형 측정을 위하여 YBT를 통하여 절대도달거리, 종합점수, COP 변인들을 좌우발에서 측정하여 결과를 도출하였다. 연구결과로 YBT 시 후외측, 후내측, 종합점수에서 단안 차단(좌우 눈 차단)이 양안 사용보다 절대도달거리 및 종합점수가 높게 나타났다. COP 결과로, 전방 및 후내측 도달 시 차이가 나타나지 않았지만, 후외측 도달 시 전후 COP 속도에서 왼발은 단안 차단이 양안시 보다 전후 COP 속도가 느리게 나타났고, COP 속도에서 왼발은 단안 차단이 양안시 보다 COP 속도가 느리게 나타났다.

• 한국산학기술학회논문지
• /
• 제13권7호
• /
• pp.3074-3084
• /
• 2012

본 연구의 목적은 청소년기 특발성 척추측만증 환자를 대상으로 슬링을 이용한 요부안정화 운동프로그램이 정적 선 자세의 균형에 미치는 영향을 알아보고자 하였다. 본 연구의 대상자는 특발성 척추측만증을 진단 받은 환자 40명을 무작위로 두군으로 나눈 후 실험군(n=20)은 슬링 요부안정화 운동, 대조군(n=20)은 단지 자세교육만 실시하였다. 두군 모두 실험 전 후 균형 수행 모니터(Balance performance monitor)을 이용하여 눈을 감은 상태에서의 양발서기 자세와 눈을 뜬 상태에서의 양발서기에서 동요거리(총, 좌우방향, 전후방향)와 동요속도(총, 좌우방향, 전후방향)를 측정하였다. 운동프로그램 적용 후에 두그룹간에 모든 변수에서 유의한 차이를 보였다. 실험군은 운동 전 후 모든 변수에서 유의한 감소를 보였다. 그러나 대조군에서는 유의한 차이를 보이지 않았다. 이상의 결과를 통해서 슬링 요부안정화 운동프로그램은 특발성 척추측만증 환자의 체중심 동요거리와 동요속도를 감소시켜 정적 선 자세 균형능력을 향상시켰으며 슬링 요부안정화 운동프로그램이 청소년기 특발성 척추측만증 환자의 균형 증진 중재가 될 수 있을 것으로 보인다.

• 화약ㆍ발파
• /
• 제8권1호
• /
• pp.3-16
• /
• 1990

The cautious blasting works had been used with emulsion explosion electric M/S delay caps. Drill depth was from 3m to 6m with Crawler Drill $\varphi{70mm}$ on the calcalious sand stone(sort-moderate-semi hard Rock). The total numbers of feet blast were 88. Scale distance were induces 15.52-60.32. It was applied to propagation Law in blasting vibration as follows. Propagtion Law in Blasting Vibration $V=K(\frac{D}{W^b})^n$ where V : Peak partical velocity(cm/sec) D : Distance between explosion and recording sites (m) W : Maximum Charge per delay-period of eighit milliseconds or more(Kg) K : Ground transmission constant, empirically determind on th Rocks, Explosive and drilling pattern ets. b : Charge exponents n : Reduced exponents Where the quantity $D/W^b$ is known as the Scale distance. Above equation is worked by the U.S Bureau of Mines to determine peak particle velocity. The propagation Law can be catagrorized in three graups. Cabic root Scaling charge per delay Square root Scaling of charge per delay Site-specific Scaling of charge per delay Charge and reduction exponents carried out by multiple regressional analysis. It's divided into under loom and over loom distance because the frequency is verified by the distance from blast site. Empirical equation of cautious blasting vibration is as follows. Over 30m----under l00m----- $V=41(D/3\sqrt{W})^{-1.41}$ -----A Over l00m-----$V= 121(D/3\sqrt{W})^{-1.66}$-----B K value on the above equation has to be more specified for furthur understang about the effect of explosives, Rock strength. And Drilling pattern on the vibration levels, it is necessary to carry out more tests.

• 화약ㆍ발파
• /
• 제9권4호
• /
• pp.3-12
• /
• 1991

The cautious blasting works had been used with emulsion explosion electric M /S delay caps. Drill depth was from 3m to 6m with Crawler Drill 70mm on the calcalious sand stone (soft-moderate-semi hard Rock) . The total numbers of feet blast were 88. Scale distance were induces 15.52-60.32. It was applied to Propagation Law in blasting vibration as follows .Propagtion Law in Blasting Vibration V=k(D/W/sup b/)/sup n/ where V : Peak partical velocity(cm/sec) D : Distance between explosion and recording sites(m) W ; Maximum Charge per delay -period of eight milliseconds or more(Kg) K : Ground transmission constant, empirically determind on the Rocks, Explosive and drilling pattern ets. b : Charge exponents n : Reduced exponents Where the quantity D/W/sup b/ is known as the Scale distance. Above equation is worked by the U.S Bureau of Mines to determine peak particle velocity. The propagation Law can be catagrorized in three groups. Cabic root Scaling charge per delay Square root Scaling of charge per delay Site-specific Scaling of charge delay Charge and reduction exponents carried out by multiple regressional analysis. It's divided into under loom and over loom distance because the frequency is varified by the distance from blast site. Empirical equation of cautious blasting vibration is as follows. Over 30m--under 100m----V=41(D/ W)/sup -1.41/-----A Over l00m---------V=121(D/ W)/sup -1.56/-----B K value on the above equation has to be more specified for furthur understand about the effect of explosives. Rock strength, And Drilling pattern on the vibration levels, it is necessary to carry out more tests.

• Physical Therapy Rehabilitation Science
• /
• 제8권3호
• /
• pp.158-161
• /
• 2019

Objective: Attentional focus is one of the critical factors that has consistently been demonstrated to enhance motor performance and motor skill. Focusing attention on the inside of the body while engaging in a particular exercise is called internal focus (IF) and focus on the external environment is called external focus (EF). The purpose of this study was to identify effects of IF and EF of attention on postural balance in healthy school-aged children. Design: Cross-sectional study. Methods: Twenty-four healthy school-aged children participated in this study. School-aged children was defined as children ages 8-12 years old. They performed the one-legged standing with EF (focusing on the marker at the level of participants' chest and 150 cm away), IF (focusing the supporting feet), and control (no instruction) respectively. The order of the focus condition was randomly selected. The center of pressure (COP) range, distance, and velocity was measured to compare the effects of applying different attentional focuses in the three conditions. Results: The results of our study show that differences in COP range, distance, and velocity among groups were not significant between the different attentional focuses, although all variables of EF were smaller than IF. It is postulated that the reason for this may be that school school-aged children between 8-12 years old go through a transitional phase from IF to EF in effective motor learning. Conclusions: These findings reveal that the type of attentional focus did not have any effect on postural balance in healthy school-aged children.

• 한국전문물리치료학회지
• /
• 제28권2호
• /
• pp.154-160
• /
• 2021

Background: Theoretically, balance is affected by the height of center of mass (COM) during quiet standing. However, no one examined this in humans with variables derived from the center of pressure (COP). Objects: We have conducted balance experiment to measure COP data during quiet standing, in order to examine how the COP measures were affected by the height of COM, vision, floor conditions, and gender. Methods: Twenty individuals stood still with feet together and arms at sides for 30 seconds on a force plate. Trials were acquired with three COM heights: 1% increased or decreased, and not changed, with two vision conditions: eyes closed (EC) and eyes open (EO), and with two floor conditions: unstable (foam pad) and stable (force plate) floor. Outcome variables included the mean distance, root mean square distance, total excursion, mean velocity, and 95% confidence circle area. Results: All outcome variables were associated with the COM height (p < 0.0005), vision (p < 0.0005), and floor condition (p < 0.003). The mean velocity and 95% confidence circle area were 5.7% and 21.8% greater, respectively, in raised COM than in lowered COM (24.6 versus 23.2 mm/s; 1,013.4 versus 832.3 mm²). However, there were no interactions between the COM height and vision condition (p > 0.096), and between the COM height and floor condition (p > 0.183) for all outcome variables. Furthermore, there was no gender difference in all outcome variables (p > 0.186). Conclusion: Balance was affected by the change of COM height induced by a weight belt in human. However, the effect was not affected by vision or floor condition. Our results should inform the design of balance exercise program to improve the outcome of the balance training.

• 제어로봇시스템학회논문지
• /
• 제11권1호
• /
• pp.58-66
• /
• 2005

Usual human gait can be modeled as continual impact phenomenon that happens due to the topological change of the kinematic structure of the two feet. The human being adapts his own control algorithm to minimize the ill effect due to the collision with the environment. In order to operate a Humanoid robot like the human being, it is necessary to understand the physics of the impact and to derive an analytical model of the impact. In this paper, specially, we focus on impact analysis of the kicking motion in playing soccer. At the instant of impact, the external impulse exerted on the ball by the foot is an important property. Initially, we introduce the complete external impulse model of the lower-extremity of the human body and analyze the external impulses for several kicking postures of the lower-extremity. Secondly, a trajectory-planning algorithm of a ball, in which the initial velocity and the launch angle of the ball are calculated for a desired trajectory of the ball, will be introduced. The aerodynamic effect such as drag force and lift force is also considered. We carry out numerical simulation and experimentation to verify the effectiveness of the proposed analytical methodology.