• Korean Journal of Applied Biomechanics
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• v.31 no.3
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• pp.168-175
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• 2021

Objective: To investigate the static and dynamic analysis of ankle joint complex between subjects with chronic ankle instability (CAI) and healthy controls. Method: A total of 38 subjects and CAI group (N=19) and healthy control (N=19) participated in this first study. Variables that were measured in this study were as follows: 1) Subtalar joint axis inclination and deviation 2) Rearfoot angle 3) Navicular drop test 4) Heel alignment view in alignment analysis. Intra Correlation Coefficient (ICC) is used for reliability. A secondary 17 subjects are recruited including 9 of CAI and healthy for gait analysis between group. Lower extremity sagittal, frontal, and transverse kinematics were measured. All data were analyzed to ensemble curve analysis. Results: 1) There were statistically significant differences in standing rearfoot, navicular drop, heel alignment view, subtalar joint (STJ) inclination and deviation. 2) Only in sagittal, meaningful difference is showed during walking in gait analysis. Conclusion: Morphological problem can affect ankle sprain in aspect of structure with no relation to compensation of neuromuscular.

• Journal of Korean Physical Therapy Science
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• v.27 no.3
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• pp.25-34
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• 2020

Background: Gait analysis is an important measurement for health professionals to assess gait patterns related to functional limitations due to neurological or orthopedic conditions. The purpose of this study was to investigate the reliability of the newly developed portable gait analysis system (PGAS). Design: Cross-sectional design. Test-retest study. Methods: The PGAS study was based on a wearable sensor, and measurement of gait kinematic parameters, such as gait velocity, cadence, step length and stride length, and joint angle (hip, knee, and ankle) in stance and swing phases. The results were compared with a motion capture system (MCS). Twenty healthy individuals were applied to the MCS and PGAS simultaneously during gait performance. Results: The test-retest reliability of the PGAS showed good repeatability in gait parameters with mean intra-class correlation coefficients (ICCs) ranging from 0.840 to 0.992, and joint angles in stance and swing phase from 0.907 to 0.988. The acceptable test-retest ICC was observed for the gait parameters (0.809 to 0.961), and joint angles (0.800 to 0.977). Conclusion: The results of this study indicated that the developed PGAS showed good grades of repeatability for gait kinematic data along with acceptable ICCs compared with the results from the MCS. The gait kinematic parameters in healthy subjects can be used as standard values for adopting this PGAS.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.751-758
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• 2005

In this study, the Discrete Element Code was applied to the analysis of falling rock blocks. The simulation was performed using the PFC2D computer code. Falling rock blocks should be applied as additional force to each others. The force affect the motion of falling rock blocks. This was used to find out the behavior of each blocks. This study revealed that the DEM can successfully capture the behavior of falling rock blocks.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.951-952
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• 2008

This paper proposes a new method for image composition which estimates the rotation angle of human hand and uses the reserved image in real-time camera images. First, we capture a background image and extract a interesting region by background subtraction. Next, we estimate the skin region from the interesting region and calculate the rotation angle of estimated skin region using PCA(Principal Components Analysis). Finally, we composite the reserved image for the calculated rotation angle in camera images. The proposed method can be applied to control the 3D avatar for marker-less augmented reality.

• Proceedings of the ESK Conference
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• 1996.10a
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• pp.59-65
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• 1996

인간의 얼굴 표정은 인간의 감성이 가장 잘 나타나는 부분이다 . 따라서 전통적으로 인간의 표정을 감 성과 연관 지어 연구하려는 많은 노력이 있어 왔다. 최근에는 얼굴 온도 변화를 측정하는 방법, 근전도(EMG; Electromyography)로 얼굴 근육의 움직임을 측정하는 방법, 이미지나 동작분석에 의한 얼굴 표정의 연구가 가능 하게 되었다. 본 연구에서는 인간의 얼굴 표정 변화를 3차원 동작분석 장비를 이용하여 측정하였다. 얼굴 표정 의 측정을 위해 두가지의 실험을 계획하였는데, 첫번 째 실험에서는 피실험자들로 하여금 웃는 표정, 놀라는 표정, 화난 표정, 그리고 무표정 등을 짓게 한 후 이를 측정하였으며, 두번째 실험에스는 코미디 영화와 공포 영화를 피 실험자들에게 보여 주어 피실험자들의 표정 변화를 측정하였다. 5명의 성인 남자가 실험에 참여하였는데, 감성을 일으킬 수 있는 적절한 자극 제시를 못한 점 등에서 처음에 기도했던 6개의 기본 표정(웃음, 슬픔, 혐오, 공포, 화남, 놀람)에 대한 모든 실험과 분석이 수행되지 못했다. 나머지 부분을 포함한 정교한 실험 준비가 추후 연구 에서 요구된다. 이러한 연구는 앞으로 감성공학, 소비자 반응 측정, 컴퓨터 애니메이션(animation), 정보 표시 장치(display) 수단으로서 사용될 수 있을 것이다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.5
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• pp.431-437
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• 2013

Measured acoustic signal from operating high speed train contains frequency change called doppler shift due to its motion. To avoid this doppler shift wind tunnel test is required. But scaledown of model can cause change of source characteristics. And measurements using some part of train cannot reproduce real flow condition. The best way to recognize real noise source characteristics is measurement from operating high speed train but doppler shift makes it hard. So, we developed simple dedopplerization technique for one microphone and applied to field test data of high speed train. Through this, we could capture real frequency of noise from operating high speed train.

• Smart Structures and Systems
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• v.18 no.1
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• pp.117-138
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• 2016

In this paper a different formulation for the response of structural systems controlled by Tuned Liquid Column Damper (TLCD) devices is developed, based on the mathematical tool of fractional calculus. Although the increasing use of these devices for structural vibration control, it has been demonstrated that existing model may lead to inaccurate prediction of liquid motion, thus reflecting in a possible imprecise description of the structural response. For this reason the recently proposed fractional formulation introduced to model liquid displacements in TLCD devices, is here extended to deal with TLCD controlled structures under base excitations. As demonstrated through an extensive experimental analysis, the proposed model can accurately capture structural responses both in time and in frequency domain. Further, the proposed fractional formulation is linear, hence making identification of the involved parameters extremely easier.

• Structural Engineering and Mechanics
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• v.66 no.3
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• pp.369-377
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• 2018

In this article, buckling and free vibration of functionally graded (FG) nanobeams resting on elastic foundation are investigated by developing various higher order beam theories which capture shear deformation influences through the thickness of the beam without the need for shear correction factors. The elastic foundation is modeled as linear Winkler springs as well as Pasternak shear layer. The material properties of FG nanobeam are supposed to change gradually along the thickness through the Mori-Tanaka model. The small scale effect is taken into consideration based on nonlocal elasticity theory of Eringen. From Hamilton's principle, the nonlocal governing equations of motion are derived and then solved applying analytical solution. To verify the validity of the developed theories, the results of the present work are compared with those available in literature. The effects of shear deformation, elastic foundation, gradient index, nonlocal parameter and slenderness ratio on the buckling and free vibration behavior of FG nanobeams are studied.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1999.06a
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• pp.111-118
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• 1999

Recently computer can make cyberspace to walk through by an interactive virtual reality technique. An a avatar in cyberspace can bring us a virtual face-to-face communication environment. In this paper, an avatar is realized which has a real face in cyberspace and a multiuser communication system is constructed by voice transmitted through network. Voice from microphone is transmitted and analyzed, then mouth shape and facial expression of avatar are synchronously estimated and synthesized on real time. And also an entertainment application of a real-time voice driven synthetic face is introduced and this is an example of interactive movie. Finally, face motion capture system using physics based face model is introduced.

• Advances in nano research
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• v.5 no.2
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• pp.113-126
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• 2017

This paper proposes a new nonlocal higher-order hyperbolic shear deformation beam theory (HSBT) for the static bending and vibration of nanoscale-beams. Eringen's nonlocal elasticity theory is incorporated, in order to capture small size effects. In the present model, the transverse shear stresses account for a hyperbolic distribution and satisfy the free-traction boundary conditions on the upper and bottom surfaces of the nanobeams without using shear correction factor. Employing Hamilton's principle, the nonlocal equations of motion are derived. The governing equations are solved analytically for the edges of the beam are simply supported, and the obtained results are compared, as possible, with the available solutions found in the literature. Furthermore, the influences of nonlocal coefficient, slenderness ratio on the static bending and dynamic responses of the nanobeam are examined.