• 한국체육학회지인문사회과학편
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• v.57 no.3
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• pp.345-356
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• 2018

Objective: The purpose of this study was to investigate the local stability of the lower extremity joints and muscle activation patterns of the lower extremity during walking between falling and non-falling group in the elderly women. Method: Forty women, heel strikers, were recruited for this study. Twenty subjects (age:72.55±5.42yrs; height:154.40±4.26cm; mass:57.40±6.21kg; preference walking speed:0.52±0.17m/s; fall frequency=1.70±1.26 times) had a history falls(fall group) within two years and Twenty subjects (71.90±2..90yrs; height:155.28±4.73cm; mass:56.70±5.241kg; preference walking speed: 0.56±0.13m/s) had no history falls(non-fall group). While they were walking on a instrumented treadmill at their preference speed for a long while, kinematic and EMG signals were obtained using 3-D motion capture and wireless EMG electrodes, respectively. Local stability of the ankle and knee joint were calculated using Lyapunov Exponent (LyE) and muscles activation and their co-contraction index were also quantified. Hypotheses were tested using one-way ANOVA and Mann-Whitey. Spearman rank was also used to determine the correlation coefficients between variables. Level of significance was set at p<.05. Results: Local stability in the knee joint adduction-abduction was significantly greater in fall group than non-fall group(p<.05). Activation of anterior tibials that acts on the foot segment dorsal flexion was greater in non-fall group than fall group(p<.05). CI between gastrocnemius and anterior tibials was found to be significantly different between two groups(p<.05). In addition, there was significant correlation between CI of the leg and LyE of the ankle joint flexion-extention in the fall group(p<.05). Conclusion: In conclusion, muscles that act on the knee joint abduction-adduction as well as gastrocnemius and anterior tibials that act on the ankle joint flexion-extention need to be strengthened to prevent from potential fall during walking.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.2
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• pp.101-107
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• 1992

디입그로잉용 냉간 압연 강판의 인장시험편에 디지탈 이미지 프로세싱 기술을 적용하여 표면에서의 변형 및 변형도 분포 구하는 방법을 제안한다. 이 방법은 시편표면상의 절점 위치를 이미지 프로세싱에 의해 결정하는 부분과 이들 위치점들을 이용하여 변형도를 계산하는 두 부분으로 구성되어,있다. 본 연 구에서는 시편상의 각 절점 위치를 구하기 위해 검은 원형의 반점들로 배열된 사각 형상의 격자를 사용하 였고, 이미지 프로세싱에 의해 구해진 절점 좌표를 이용하여 소재 표면에서의 변형 패턴, 주 변형도 분포, 유효 변형도 분포, 임계 변형도 등을 구하였다. 인장시험하는 동안 시편 표면상의 국부 네킹이 발생될때 까지 주변형도에 의한 변형 이력은 거의 적선적으로 변형되고 있기 때문에, 유효 변형도 값은 매 변형 단계마다 변형도 증분의 누적에 관계없이 거의 일정한 값을 보여주고 있었으며, 최대 유효 변형도는 시편의 중앙부에서 나타나고 있음을 알 수 있었다.

• Journal of the Korean Professional Engineers Association
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• v.27 no.3
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• pp.121-131
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• 1994

It is very difficult to partially describe the hull shape made up of 3-dimensional free form surface. With computerizing skill in ship design, the geometric modeling technique has been developed. In hull shape modeling, the blending technique has not yet been adapted to the hull shape surface has a variable curvature. By adapting the blend surface, small surface on drawing plane is to be softly blended with given hull surface and a projecting part. This study has adapted to the ship design one of the blending methods by which offsets data of the blend surface can be obtained by the input of blend radius on two base surfaces.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.3
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• pp.1-12
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• 1994

A model engine having a flat cylinder head and a piston face and an off-center intake valve is investigated in this analysis. Calculation domain is confined to the half of the cylinder with swirl free inlet velocity condition. Due to the absence of measured inlet conditions, the inlet flowrates during induction period are calculated from overall mass and energy conservation requirements. Finite difference equation for velocity and pressure were solved by modified SIMPLER algorithm, standard k-$\varepsilon$turbulence model and hybrid scheme. From the result of prediction, dimensionless velocity distribution and turbulence intensities are investigated at each crank angle.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.5
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• pp.507-512
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• 2007

This paper presents a tracking filter with ship's motion compensation for a ship-borne radar tracking system. The ship's maneuver is described by displacement and rotational motions in the ship-centered east-north frame. The first order Taylor series approximation of the measurement error covariance of the converted measurement is derived in the ship-centered east-north frame. The ship's maneuver is compensated by incorporating the measurement error covariance of the converted measurement and displacement of the position state in the tracking filter. The simulation results via 500 Monte-Carlo runs show that the proposed method follows the target successfully and provides consistent tracking performance during ship's maneuvers while the conventional tracking filter without ship motion compensation fails to track during such periods.

• Journal of the Korean Society for Precision Engineering
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• v.8 no.4
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• pp.107-117
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• 1991

The dynamic stability problem of nonconservative system is one of the important problems. In this study, flexible missile with mass variation is regarded as a free Timoshenko beam subjected to a controlled follower force. The stability was studied numerically through the finite element method. Through the study, the obtained results are as follows: [1] Without force direction control (1) In the case of no mass reduction, the existence of concentrated mass increases critical follower force. (2) Mass reduction rate of the beam slightly effects on the change of critical follower force. [2] With force direction control (1) Shear deformation parameter S contributes insignificantly to the force at instability when $S{\geq}10^4$. (2) With mass variation, increase of concentrated mass increases critical follower force at instbility. (3) The type of promary instability is determined by the sensor location.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1397-1401
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• 2007

낙동강에 위치한 하회마을의 점사주는 상류에 안동 및 임하 다목적댐이 건설되면서, 수량이 조절됨에 따라 토사수리학적 특성이 상당히 변화되었으며, 식생이 발생하는 등 옛 모습을 상실해 가고 있는 지역이다. 이 연구는 낙동강의 중상류에 위치한 하회지구에 평면 이차원 하상변동 및 수질예측 수치모형인 KU-RLMS 모형을 적용하여 하회마을 앞의 점사주에 영향을 미치는 수리학적 특성 변화를 규명할 목적으로 수행하였다. KU-RLMS 모형은 하천 및 저수지의 국부적인 수리, 수질, 유사이동 해석을 위해 개발된 평면 이차원 비정상 수치모형이다. 직사각형 격자를 사용하는 유한차분법의 단점을 보완하기 위해, 흐름 계산을 위한 지배 방정식은 3차원 Reynolds 방정식으로부터 수심적분된 2차원 연속방정식과 운동량방정식을 불규칙한 경계를 현실적으로 모사할 수 있는 직교곡선 좌표계로 변환한 방정식을 사용한다. 안동다목적댐과 임하다목적댐의 방류량, 수공구조물 설치 여부 등을 고려하여 수치모의조건을 결정하였으며, 각 조건에 대한 흐름 변화특성을 분석하였다.

• Journal of Ocean Engineering and Technology
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• v.26 no.5
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• pp.55-62
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• 2012

In this paper, the rigid lid boundary condition is applied to simulate the influence of floating structures such as ships or pontoons, and the pressure term in both the momentum equations and continuity equation are modified. The pressure of a floating structure under the free surface is dependent on the draft of the structure, generally called a ship. If the free surface is covered by a floating structure, the free surface cannot move freely. The water level should be fixed, using a rigid lid boundary condition. This boundary condition is implemented by reducing the storage area of the grid cell with a factor between zero and one. The numerical model developed by Hong (2009) is verified through a comparison with experimental results, and the influence of the reduction factor is investigated using the verified numerical model.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.5
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• pp.11-17
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• 2010

In this parer, face recognition method which can be applied to ITCS (interactive TV control system) is proposed. We extracted ULBP(uniform local binary pattern) histogram feature from infra-red images, and we detected left-right eyes and face region by using SVM classifier. Then, We implemented face recognition system which is using Gabor transform and ULBP histogram feature and applied to personal verification for ITCS.

• Journal of KIISE:Software and Applications
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• v.37 no.4
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• pp.305-310
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• 2010

In this paper, we propose a heuristic algorithm for motion correspondence based on a point series similarity. A point series is a sequence of points which are sorted in the ascending order of their x-coordinate values. The proposed algorithm clusters the points of a previous frame based on their local adjacency. For each group, we construct several potential point series by permuting the points in it, each of which is compared to the point series of the following frame in order to match the set of points through their similarity based on a proximity constraint. The longest common subsequence between two point series is used as global information to resolve the local ambiguity. Experimental results show an accuracy of more than 90% on two image sequences from the PETS 2009 and the CAVIAR data sets.