Effect of slipper wearing and carrying positions of infant on dynamic stability and kinetic variable during level walking

Ryew, Che-Cheong,Hyun, Seung-Hyun 한국운동재활학회 2018 JER Vol.14 No.4

<P>Recently though various hip seats for carrying infant of women was designed and developed, then, wearing slipper may restrain the movement of bare foot. The study was undertaken to investigate the dynamic stability and kinetic variables according to between position of carrying infant and wearing slipper. Adult female (n=10) and under one year age of infant (n=10) participated in the study. Extrapolated center of mass, center of pressure, ground reaction force (GRF), and leg stiffness of gait characteristics using 3-dimensional cinematography and GRF were analyzed. Dynamic stability according to position of carrying infant and wearing slipper was not significant. While when carried an infant against normal gait showed significant difference in breaking force, leg stiffness and loading rate (<I>P</I><0.001). Of which breaking force and vertical impulse were more increased when the back-carried against fore-carried of trunk. Thus it resulted in transformation on types of impulse transfer to leg and COG of women’s carrying infant, which may be strategy for securing a dynamic stability. Therefore experts related with exercise rehabilitation should understand sufficiently on gait characteristics of women with diseases on muscular-skeletal system and perform effective rehabilitation and treatment.</P>

Does Strategy of Downward Stepping Stair Due to Load of Additional Weight Affect Lower Limb's Kinetic Mechanism?

Ryew, Checheong,Yoo, Taeseok,Hyun, Seunghyun The Institute of Internet 2020 International journal of advanced smart convergenc Vol.9 No.4

This study measured the downward stepping movement relative to weight change (no load, and 10%, 20%, 30% of body weight respectively of adult male (n=10) from standardized stair (rise of 0.3 m, tread of 0.29 m, width of 1 m). The 3-dimensional cinematography and ground reaction force were also utilized for analysis of leg stiffness: Peak vertical force, change in stance phase leg length, Torque of whole body, kinematic variables. The strategy heightened the leg stiffness and standardized vertical ground reaction force relative to the added weights (p<.01). Torque showed rather larger rotational force in case of no load, but less in 10% of body weight (p<.05). Similarly angle of hip joint showed most extended in no-load, but most flexed in 10% of body weight (p<.05). Inclined angle of body trunk showed largest range in posterior direction in no-load, but in vertical line nearly relative to added weights (p<.001). Thus the result of the study proved that downward stepping strategy altered from height of 30 cm, regardless of added weight, did not affect velocity and length of lower leg. But added weight contributed to more vertical impulse force and increase of rigidity of whole body than forward rotational torque under condition of altered stepping strategy. In future study, the experimental on effect of weight change and alteration of downward stepping strategy using ankle joint may provide helpful information for development of enhanced program of prevention and rehabilitation on motor performance and injury.

숙련자와 미숙련자의 배드민턴 스매시 동작의 운동학적 비교 분석

류재청,김익상 한국운동역학회 2003 한국운동역학회지 Vol.13 No.2

Ryew, C-C and Kim, I-S. Kinematic Analysis of Badminton Smashing Between the Skilled and the Unskilled. Korean Journal of Sport Biomechanics, Vol. 13, No. 2, pp. 139-160. The purpose of this study was to suggest the guideline for scientific and quantitative skill acquisition methods of badminton smashing so that the novice could learn the motions of badminton smashing efficiently. The subject participated consisted of total 6 middle school students of the skilled(3) and the unskilled(3). The cinematographical experimental & Analysis equipments used in the study were composed of two Model D-5100 Video Cameras, a control point, a synchronization timer and Kwon3d motion analysis system. The conclusions obtained were as follows; 1. It was necessary for the unskilled to learn the smashing impact phase in situation of max. Velocity of COG in order to minimize the timing loss phase. 2. Particularly, The power from segments of Power Zone must participate in utilization in sequence of order of trunk-upper arm-forearm-hand-racket segment in both the skilled and the unskilled. 3. Therefore It was necessary for the unskilled to do smashing practice for cumulated sum of absolute & relative velocity transfer into shuttle cock after adjusting anterior-posterior tilting angle and max timing, in sequence of segment recruited.

수중관광 및 학습장을 위한 레저스포츠 포인트 개발을 위한 타당성 연구

류재청(Ryew Che-Cheong) 한국체육과학회 2001 한국체육과학회지 Vol.10 No.1

The survey was undertaken to suggest validation of underwater leisure tourism point development of Eu-Yeng coast line of Jeju city after comprasion in economic level, quality of underwater scene, distribution of underwater animal & plants, underwater geographic figure, safety, a number of visitors through a year with other points of Jejudo. On the basis of survey conclusions obtained was to be based on 「aviation-ocean-mid mountain」 on each air leisure sport-golf leisure sports-ocean sports tourism mixed passive tourism and eco-natural environmental participating tourism cconcepts for underwater tourism of leports and experiencing for youth. In terms of 21c Jeju International no-visa metropolitan city, its center Jeju city will be faced that resident population inflow, improved economic situation, increased leisure time, ect phenomenia will be necessary for its city to develope active participating style's leports-tourism items differientiating with other local government's items By development of tourism items of eco-natural environmental leisuresports style, Tourism differentiated with the other will be elevated competition and for this future developmental direction must be based on 「ocean-midmountain-orum-sky」 of various ocean tourism leports, golf tourism, aviation tourism leport of participating style's tourism by only Jejudo's natural characteristics. Particularly corncerned with ocean leport tourism of Jeju city, It will be desirable to develop, investment of facility, offer various participate program linking Eho beach-Euyeng cost line point-Leports park-Yongdoam concerned with ocean leport tourism of Jeju city's Euyeng cost load point. When developed of experiencing underwater tourism point, Effects of income level, occupational problem will be futher good condition and offer differentiated tourism items to other local government's.

The Mechanism Study of Gait on a Load and Gender Difference

Checheong Ryew,Seunghyun Hyun 한국인터넷방송통신학회 2021 International Journal of Internet, Broadcasting an Vol.13 No.1

Gait kinematics and kinetics have a similar tendency between men and women, yet it remains unclear how walking while carrying a load affects the gait mechanism. Twenty adults walked with preferred velocity on level ground of 20 m relative to change of a load carriage (no load, 15%, 30% of the body weights) aimed to observe gait mechanism. We measured gait posture using the three-dimensional image analysis and ground reaction force system during stance phase on left foot. In main effect of gender difference, men showed increased displacement of center of gravity (COG) compared to women, and it showed more extended joint angle of hip and knee in sagittal plane. In main effect of a load difference, knee joint showed more flexed postuel relative to increase of load carriage. In main effect of load difference on the kinetic variables, mediallateral force, anterior-posterior force (1st breaking, 2nd propulsive), vertical force, center of pressure (COP) area, leg stiffness, and whole body stiffness showed more increased values relative to increase of load carriage. Also, men showed more increased COP area compared to women. Interaction showed in the 1st anteriorposterior force, and as a result of one-way variance analysis, it was found that a load main effect had a greater influence on the increase in the magnitude of the braking force than the gender. The data in this study explains that women require little kinematic alteration compared to men, while men in more stiff posture accommodate an added load compared to women during gait. Additionally, it suggests that dynamic stability is maintained by adopting different gait strategies relative to gender and load difference.

한발 착지 시 수직지면반력과 동적자세안정성의 성별 차이: 양측 다리 간 불균형

류재청 ( Ryew Che-cheong ),현승현 ( Hyun Seung-hyun ) 제주대학교 체육진흥센터(구 제주대학교 체육과학연구소) 2019 체육과학연구 Vol.25 No.-

Rapid impulse loaded may be transferred to the lower extremity from ground contact in a condition that landing from a jump may be decreased the dynamic postural stability in female. The purpose of this study was to investigate the gender’s difference in dynamic postural stability and peak vertical force during single leg landing. A total of twelve subjects(male n=6, range: age 20~22 years, heights 166.23~177.10 cm, weights 58.61~86.51 kg, female n=6, range: age 19~21 years, heights 156.90~169.21 cm, weights 48.61~72.91 kg) participated in this study. The peak vertical force and dynamic postural stability index(medial-lateral, anterior-posterior, and vertical stability index) were determined by time-function and frequency domain during drop landing. A mixed model(2 gender×2 landing legs) of repeated measures design was used to determine the effects of gender and limb dominance on dynamic postural stability and peak vertical force. The peak vertical force in female group showed significant difference statistically with more higher force than that of male group. Also, MLSI, VSI, and DPSI in male group showed significant difference statistically with more decreased than that of female group. VSI in right leg showed significant difference statistically with more decreased than that of left leg. The results indicate that females have higher dynamic postural stability scores in the vertical and medial-lateral direction as well as the composite score. This suggests that female used different dynamic postural stability and shock absorption strategies in contrast to male.

대형화물 트럭의 운전석에서 점프 시 착지기술이 다리강성과 COP변인에 미치는 영향

류재청 ( Ryew Che-cheong ),현승현 ( Hyun Seung-hyun ) 제주대학교 해양스포츠센터 2018 해양스포츠연구 Vol.8 No.2

The purpose of this study was to investigate the effect of landing techniques on center of Pressure and leg stiffness during jumping from driver's seat in large-cargo truck. Participants Selected as subject were composed of adult male(mean age: 29.66±6.47 yrs, mean heights: 176.91±3.80 cm, mean weights: 76.16±2.33 kg), and performed descending motions of 2 types(soft and stiff landing). The soft and stiff landing techniques were defined by maximum knee flexion angles(soft landing) of gerater than and less than 90 degrees from full extension(stiff landing), respectively. As a result, dimensionless leg stiffness, peak vertical force(PVF) time, and center of pressure area didn't show significant differences statistically according to the landing techniques. Also, PVF at soft landing motion showed decrease than that of stiff landing motion during jumping from driver's seat in cargo truck. Combined, these results show that jumping from in a driver's seat of large-cargo truck increase the impact force regardless of the landing technique.

Does Strategy of Downward Stepping Stair Due to Load of Additional Weight Affect Lower Limb’s Kinetic Mechanism?

Checheong Ryew,Taeseok Yoo,Seunghyun Hyun 한국인터넷방송통신학회 2020 Journal of Advanced Smart Convergence Vol.9 No.4

This study measured the downward stepping movement relative to weight change (no load, and 10%, 20%, 30% of body weight respectively of adult male (n=10) from standardized stair (rise of 0.3 m, tread of 0.29 m, width of 1 m). The 3-dimensional cinematography and ground reaction force were also utilized for analysis of leg stiffness: Peak vertical force, change in stance phase leg length, Torque of whole body, kinematic variables. The strategy heightened the leg stiffness and standardized vertical ground reaction force relative to the added weights (p<.01). Torque showed rather larger rotational force in case of no load, but less in 10% of body weight (p<.05). Similarly angle of hip joint showed most extended in no-load, but most flexed in 10% of body weight (p<.05). Inclined angle of body trunk showed largest range in posterior direction in no-load, but in vertical line nearly relative to added weights (p<.001). Thus the result of the study proved that downward stepping strategy altered from height of 30 cm, regardless of added weight, did not affect velocity and length of lower leg. But added weight contributed to more vertical impulse force and increase of rigidity of whole body than forward rotational torque under condition of altered stepping strategy. In future study, the experimental on effect of weight change and alteration of downward stepping strategy using ankle joint may provide helpful information for development of enhanced program of prevention and rehabilitation on motor performance and injury.

외발서기 시 무릎 보호대의 착용이 균형성에 미치는 영향

류재청 ( Ryew Che-cheong ),현승현 ( Hyun Seung-hyun ) 제주대학교 해양스포츠센터 2017 해양스포츠연구 Vol.7 No.2

The purpose of this study was to investigate the effect of knee compression band on balance during single-leg stance. The participants consisted of healthy adult male(n=9). The analyzed variables included of the ΔCOP(center of pressure)x, ΔCOPy, CDP area, medial-lateral COP, and anterior-posterior COP during single leg stance. As a result, Δ COPx, Δ COPy, and COP area didn't show significant differences statistically according to the bilateral stance legs(p>.05), but wearing of knee compression band showed decrease than that of non-wearing of knee compression band(p< .01). Also, ML COP didn’t show significant differences statistically according to the bilateral stance legs and wearing of knee compression band(p >.05), while, AP COP at dominant leg(right leg) showed decrease than that of non-dominant leg(left leg) during one stance leg(p<.05). Combined, these results show that knee compression band may provide both a performance enhancement and an injury reduction role during static-based posture control.

보행 시 가방무게의 일측성 부하가 동적안정성지수 및 COP 변인에 미치는 영향

류재청(Ryew, Che-Cheong),윤상택(Yoon, Sang-Taek),현승현(Hyun, Seung-Hyun) 한국체육과학회 2014 한국체육과학회지 Vol.23 No.3

This purpose of this study was to analyze the effect on the asymmetric load of bag weights for dynamic postural stability index & Center of Pressure variables during level walking. Participants selected as subject were consisted of young women(n=10), divided into the kinds of 3 bag weights(0kg, 3kg, 5kg).. Analyzed GRF variables during gait were medial-lateral (ML), anterior-posterior(AP), vertical(V), dynamics postural stability index(DPSI), ΔCOPx, ΔCOPy, COP area, medial-lateral(M-L), anterior-posterior(A-P) deviation of venter of pressure. The results analyzed from the above were as follows; 1. MLSI, APSI, VSI and DPSI didn`t show significant different statistically according to increase of bag weights, But, 5kg bag weight showed more decrease in dynamics postural stability index than that 0kg, 3kg bag weights during level walking. 2. Among variables of center of pressure, 5kg bag weight showed more linear relationship in pathway than that of 0kg, 3kg bag weights in ΔCOPx. Also, COP area showed increasing tendency according to decrease of bag weights. 3. M-L COPD didn`t show significant different statistically according to increase of bag weights, finally A-P COPD showed significant difference statistically in dynamic postural according to increase of bag weights.