• 한국정밀공학회지
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• 제4권4호
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• pp.56-71
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• 1987

Determination of navigation variables (latitude, longitude, and altitude) near the earth's surface is termed 'Terrestrial Navigation'. The quantities that are measured inertially are the total acceleration (or the integral fo this acceleration over a fixed time interval) and the total angular rate (or the integral of this angular rate over the same time interval). These measurements when suitably compensated can be manipulated to yield the navigation variables. Hence, it is essential that the initial values of position, orientation and velocity are accurately set up during the initial alignment process. Initial alignment of gimballed inertial navigation system ( GINS) is accomplished by gyrocompassing techniques. These cannot be used, in the case of strapdown inertial navigation system(SDINS), where the inertial instruments are directly strapped down to a vehicle frame. The basic objective of this paper is the development of digital method for the determination of the initial axes erection of a SDINS from vibration and sway currupted data on the launch pad.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1211-1214
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• 2004

High-heeled women have been identified with balance control problems. The purposes of this study were to objectively quantify the displacements and velocities of center-of-pressure (COP) of body during waist pulling and to compare the differences between barefooted and high-heeled situations. We used a waist pulling system which has three different magnitudes to sway the subjects. We found that the kinematic information of barefooted and high-heeled women's COP is very important in understanding the mechanism of postural balance control of women in every-day life. In the high-heeled's case, the displacement of COP increases in 200％ as against bare footed. Also the velocity variation of COP grows three times than the bare footed. COP analysis in postural balance study of high-heeled women is also considered useful in development of the safety systems that prevent high-heeled women from falling

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제20권4호
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• pp.309-332
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• 2016

Finite element method has been applied to solve the fundamental governing equations of natural convective, electrically conducting, incompressible fluid flow past an infinite vertical plate surrounded by porous medium in presence of thermal radiation, viscous dissipation, Soret and Dufour effects. In this research work, the results of coupled partial differential equations are found numerically by applying finite element technique. The sway of significant parameters such as Soret number, Dufour number, Grashof number for heat and mass transfer, Magnetic field parameter, Thermal radiation parameter, Permeability parameter on velocity, temperature and concentration evaluations in the boundary layer region are examined in detail and the results are shown in graphically. Furthermore, the effect of these parameters on local skin friction coefficient, local Nusselt number and Sherwood numbers is also investigated. A very good agreement is noticed between the present results and previous published works in some limiting cases.

• Safety and Health at Work
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• 제6권3호
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• pp.206-210
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• 2015

Background: Fatigue has a strong impact on workers' performance and safety, but expedient methods for assessing fatigue on the job are not yet available. Studies discuss posturography as an indicator of fatigue, but further evidence for its use in the workplace is needed. The purpose of the study is to examine whether posturography is a suitable indicator of fatigue in clerical workers. Methods: Thirty-six employees (${\emptyset}$ 34.8 years, standard deviation = 12.5) participated in postural tasks (eyes open, eyes closed, arm swinging, and dual task) in the morning and afternoon. Position of their center of pressure (COP) was registered using a Nintendo Wii Balance Board and commercial software. From registered COP time series, we calculated the following parameters: path length (mm), velocity (mm/s), anterior-posterior variance (mm), mediolateral variance (mm), and confidence area ($mm^2$). These parameters were reduced to two orthogonal factors in a factor analysis with varimax rotation. Results: Statistical analysis of the first factor (path length and velocity) showed a significant effect of time of day: COP moved along a shorter path at a lower velocity in the afternoon compared with that in the morning. There also was a significant effect of task, but no significant interaction. Conclusion: Data suggest that postural stability of clerical workers was comparable in the morning and afternoon, but COP movement was greater in the morning. Within the framework of dynamic systems theory, this could indicate that the postural system explored the state space in more detail, and thus was more ready to respond to unexpected perturbations in the morning.

• 한국운동역학회지
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• 제23권1호
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• pp.37-43
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• 2013

The purpose of this study was to analyze the 12-week horse riding exercise effect on the locomotion of a body and bilateral balance and flexion/extension of trunk during the sit-to-stand(STS) in elementary and middle school students. One-hundred eleven participants were divided into three groups. Each group was subject to a different horse riding exercise: control group(n = 36), 1 time/week group(n=37), and 3 times/week group(n=38). Two-way repeated ANOVA was used to compare weight transfer time(WTT), trunk flexion velocity(TFV), trunk extension velocity(TEV), mean rising index(MRI), mean weight asymmetry( MWA) among the groups, and STS changes in before and after 12 weeks. There was a group interaction in WTT, TFV, TEV, MRI, and MWA with different responses to horse riding exercise participation. There was a significant increase in 1 time/week group and 3 times/week group of WTT, TFV, TEV, and MRI. Additionally, MWA(an index of a capacity for bilateral balance) in lower extremity was decreased in 3 times/week group. It seems that horse riding exercise positively affected musculoskeletal function of the trunk and lower extremity by accelerating locomotion and bilateral balance.

• 대한조선학회논문집
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• 제38권4호
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• pp.30-38
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• 2001

조류를 고려한 조종운동방정식을 정립한 후 선박의 운동변수 뿐만 아니라 외력 및 조류의 방향과 속도도 상태변수로 설정하여 비선형 상태방정식과 측정방정식을 표현하였다. 여기서 외력은 3차의 Gauss-Markov 프로세스로 표시하고, 조류의 방향과 속도는 일정하다고 가정하였다. 상태 추정을 위하여 확장 Kalman-Bucy 필터와 고정간격 스무더를 이용하였다. 기존의 Hwang은 실선 시운전 계측값을 이용하여 동유체력미계수 및 조류의 영향을 동시에 확장 Kalman 필터를 이용하여 추정하였으므로 매개변수의 개수가 상당히 많아지는 반면 모델링 전 추정기법을 사용하면 각각의 동유체력미계수를 추정하는 대신에 3방향의 외력과 조류 변수만을 추정한다. 측정잡음이 포함된 시뮬레이션 측정값을 적용하여 조류 변수를 추정하는 경우 실제값이 잘 추정되는 것을 확인하였다.

• 한국산학기술학회논문지
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• 제11권11호
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• pp.4418-4426
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• 2010

근피로는 자세균형과 근수축력의 악화를 유발하여 다양한 근골격계 손상을 초래한다. 본 연구는 하퇴삼두근에 근피로 유발에 의한 자세불균형과 근수축력 저하에 경피신경전기자극이 미치는 효과를 알아보고자 하였다. 2010년 3월부터 4개월간 전정계통과 시각계통에 문제가 없는 20명의 건강한 성인을 대상으로 반복운동 수행을 통하여 비복근에 근피로를 유발하였고, 유발 후 즉시 경피신경전기자극을 적용하였다. 근피로 및 경피신경전기자극에 의한 자세균형과 근수축력의 변화를 측정하기 위하여 자세동요 이동거리와 속도, 최대수의수축력을 사용하였다. 근피로 유발에 의하여 자세동요 이동거리 및 속도의 증가와 근수축력의 저하가 나타났다(p<.05). 근피로가 유발된 비복근에 경피신경 전기자극의 적용은 근피로에 의한 자세동요와 근수축력을 유의하게 개선하였다(p<.05). 이와 같은 연구결과를 통하여 족저굴곡근의 근피로는 자세균형과 근수축력에 관여되고, 경피신경전기자극은 근피로에 의한 자세불균형 및 근수축력 저하에 효과적임을 증명하였다. 경피신경전기자극은 일상생활에서 흔히 유발되는 근피로의 중재에 경피신경전기자극이 효과적인 중재 방법으로 사용될 수 있을 것으로 사료된다.

• 융합정보논문지
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• 제12권2호
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• pp.174-183
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• 2022

본 연구는 슬링을 이용한 능동 운동프로그램이 무릎 관절 전치환술 환자의 통증과 균형에 미치는 영향을 알아보고자 실시하였다. 대상자는 무릎 관절 전치환술을 받고 입원 중인 환자 20명이며, 수술 후에 CPM (Continuous passive motion) 만을 적용하는 집단 (CPM group; CG)과 CPM과 슬링을 이용한 능동 운동프로그램을 병행하는 집단 (CPM with active exercise program using sling group; CSG)으로 10명씩 무작위로 배치되었다. CG는 CPM을 주 5일, CSG는 CPM을 주 2일, 슬링을 이용한 능동 운동프로그램을 주 3일 실시하였고, 각 중재는 하루 40분씩 총 4주간 실시하였다. 통증은 VAS(Visual analog scale)을 이용하여 평가하였고, 균형은 BT4 (Balance training 4)를 이용하여 C90 area, Trace length, Sway average velocity를 눈을 뜬 상태와 감은 상태로 측정하였다. 그 결과, 두 집단 모두 통증에서 집단 내에서 유의하게 감소하였고, 집단 간의 변화량에서도 유의한 차이가 있었다. 균형에서 CG의 C90을 제외한 모든 변인이 중재 후 유의한 변화가 있었으며, 집단 간 변화량에서는 눈을 감은 상태의 C90과 Vel에서 유의한 차이가 있었다. 따라서 CPM과 슬링을 이용한 능동 운동프로그램을 함께 시행하는 것은 무릎 관절 전치환술 환자의 통증 감소와 균형 향상에 효과적인 중재라고 생각한다.

• 한국산학기술학회논문지
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• 제14권1호
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• pp.294-300
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• 2013

이 연구는 요가운동이 뇌졸중 환자에게 자가 운동 프로그램으로의 가능성을 확인하고자 요가운동을 적용하여 정적균형, 동적균형, 보행속도를 측정하였다. 뇌졸중으로 편마비 진단을 받은 입원 환자 18명을 대상으로 대조군과 요가운동군에 각각 9명씩 배정하여 주 3회 60분씩 8주간 요가운동을 실시하였다. 정적균형은 Tetrax를 사용하여 안정성지수(무게중심의 이동)와 체중분포지수를, 동적균형은 functional reach test(FRT)와 dynamic gait index(DGI)를, 보행속도는 10미터 보행 검사를 실시하였다. 그 결과 요가운동군에서 무게중심의 이동과 체중분포의 안정성, FRT와 DGI의 유의한 향상을 보였다. 대조군에서는 유의한 차이를 보이지 않았다. 보행속도에는 두 군 모두 유의한 차이를 보이지 않았다. 이는 요가운동이 뇌졸중 후 균형능력이 상실된 환자에게 체계적인 자가 운동 프로그램으로 적용 가능하다고 사료된다.

• Physical Therapy Rehabilitation Science
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• 제10권1호
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• pp.55-63
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• 2021

Objective: The purpose of this study was to examine the effects of balance training with Functional Electrical Stimulation (FES) on balance and gait in patients with chronic stroke. Design: A cross over design Methods: Nine patients with stroke were recruited into this study. They were measuring their balance ability and gait ability. The intervention "A" included 4 weeks of balance training with Functional Electrical Stimulation (FES) for 40 m/d, 3 d/wk. Intervention "B" included 4 weeks of balance training with placebo Functional Electrical Stimulation (FES) for 40 m/d, 3 d/wk. Of the 9 patients who completed the study, 5 were randomly assigned to" group A-B", and 4 to group B-A. The crossover occurred after 4 weeks. Results: Following are the specific results of balance training with Functional Electrical Stimulation (FES) on patients with chronic stroke. First, patients who received treatment A showed improvement compared with patients who received treatment B in static balance. There were significant decreases in anterioposterior, mediolateral postural sway extension and velocity moment (p<0.05) with their eyes opened and closed conditions. Second, they had significantly improved in dynamic balance (p<0.05). Lastly, there were also improvement in their gait velocity and cadence (p<0.05). Conclusions: These findings suggest that, the Functional Electrical Stimulation (FES) combined with balance training more effectively improves the balance and gait ability, I'm convinced that it could be actively used in clinics added to the conventional physical therapy in the future.