• Physical Therapy Korea
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• v.29 no.1
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• pp.70-78
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• 2022

Background: Individuals with calf muscle shortening may have decreased dynamic balance. Objects: This study aimed to investigate the effect of mobilization with movement (MWM) and myofascial release (MFR) on kinematic changes in dynamic balance in individuals with calf muscle shortening. Methods: Thirteen participants were randomly assigned to the MWM or the mobilization with movement added myofascial release (MWM-MFR) group. The MWM group received treatment with only MWM, whereas the MWM-MFR group was treated with MWM and MFR. Pre- and post-intervention passive range of motion (PROM), maximum reaching lengths, and modified star excursion balance test (MSEBT) results were compared for all participants. Wilcoxon signed-rank test and Mann-Whitney U test were used for statistical analysis. Results: The results showed significant within-group differences in ankle PROM, but no significant between-group differences. The maximum reaching length in the MWM-MFR group in the posterolateral direction was significantly different before and after the intervention (p = 0.005). This group also showed significantly reduced ankle abduction in MSEBT during the posteromedial direction section 3 (p = 0.007) and posterolateral direction section 5 (p = 0.049) compared with the MWM group. Conclusion: Combined MWM and MFR intervention improves ankle stability in the coronal plane during the posteromedial and posterolateral forward movement in dynamic balance compared with only MWM in individuals with calf shortening.

• Physical Therapy Korea
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• v.30 no.2
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• pp.110-119
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• 2023

Background: Osteoarthritis is a common condition with an increasing prevalence and is a common cause of disability. Osteoarthritic pain decreases the quality of life, and simple gait training is used to alleviate it. Knee osteoarthritis limits joint motion in the sagittal and lateral directions. Although many recent studies have activated orthotic research to increase knee joint stabilization, no study has used patellar tendon straps to treat knee osteoarthritis. Objects: This study aimed to determine the effects of patellar tendon straps on kinematic, mechanical, and electromyographic activation in patients with knee osteoarthritis. Methods: Patients with knee osteoarthritis were selected. After creating the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), leg length difference, Q-angle, and thumb side flexion angle of the foot were measured. Kinematic, kinetic, and muscle activation data during walking before and after wearing the orthosis were viewed. Results: After wearing the patellar tendon straps, hip adduction from the terminal stance phase, knee flexion from the terminal swing phase, and ankle plantar flexion angle increased during the pre-swing and initial swing phases. The cadence of spatiotemporal parameters and velocity increased, and step time, stride time, and foot force duration decreased. Conclusion: Based on the results of this study, the increase in plantar flexion after strap wearing is inferred by an increase due to neurological mechanisms, and adduction at the hip joint is inferred by an increase in adduction due to increased velocity. The increase in cadence and velocity and the decrease in gait speed and foot pressure duration may be due to joint stabilization. It can be inferred that joint stabilization is increased by wearing knee straps. Thus, wearing a patellar tendon strap during gait in patients with knee osteoarthritis influences kinematic changes in the sagittal plane of the joint.

• Structural Engineering and Mechanics
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• v.85 no.4
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• pp.433-443
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• 2023

The current paper discusses the dynamic and stability responses of cross-ply composite laminated plates by employing a refined quasi-3D trigonometric shear deformation theory. The proposed theory takes into consideration shear deformation and thickness stretching by a trigonometric variation of in-plane and transverse displacements through the plate thickness and assures the vanished shear stresses conditions on the upper and lower surfaces of the plate. The strong point of the new formulation is that the displacements field contains only 4 unknowns, which is less than the other shear deformation theories. In addition, the present model considers the thickness extension effects (ε_z≠0). The presence of the Winkler-Pasternak elastic base is included in the mathematical formulation. The Hamilton's principle is utilized in order to derive the four differentials' equations of motion, which are solved via Navier's technique of simply supported structures. The accuracy of the present 3-D theory is demonstrated by comparing fundamental frequencies and critical buckling loads numerical results with those provided using other models available in the open literature.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1996.06a
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• pp.179-200
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• 1996

The intrinsic instabilities of fluid flow occurred in the melt of the Czochralski crystal growth system Czochralski method, asymmetric flow patterns and temperature profiles in the melt have been studied by many researchers. The idea that the non-symmetric structure of the growing equipment is responsible for the asymmetric profiles is usually accepted at the first time. However further researches revealed that some intrinsic instabilities not related to the non-symmetric equipment structure in the melt could also appear. Ristorcelli had pointed out that there are many possible causes of instabilities in the melt. The instabilities appears because of the coupling effects of fluid flow and temperature profiles in the melt. Among the instabilities, the B nard type instabilities with no or low crucible rotation rates are analyzed by the visualizing experiments using X-ray radiography and the 3-D numerical simulation in this study. The velocity profiles in the Silicon melt at different crucible rotation rates were measured using X-ray radiography method using tungsten tracers in the melt. The results showed that there exits two types of fluid flow mode. One is axisymmetric flow, the other is asymmetric flow. In the axisymmetric flow, the trajectory of the tracers show torus pattern. However, more exact measurement of the axisymmetrc case shows that this flow field has small non-axisymmetric components of the velocity. When fluid flow is asymmetric, the tracers show random motion from the fixed view point. On the other hand, when the observer rotates to the same velocity of the crucible, the trajectory of the tracer show a rotating motion, the center of the motion is not same the center of the melt. The temperature of a point in the melt were measured using thermocouples with different rotating rates. Measured temperatures oscillated. Such kind of oscillations are also measured by the other researchers. The behavior of temperature oscillations were quite different between at low rotations and at high rotations. Above experimental results means that the fluid flow and temperature profiles in the melt is not symmetric, and then the mode of the asymmetric is changed when rotation rates are changed. To compare with these experimental results, the fluid flow and temperature profiles at no rotation and 8 rpm of crucible rotation rates on the same size of crucible is calculated using a 3-dimensional numerical simulation. A finite different method is adopted for this simulation. 50×30×30 grids are used. The numerical simulation also showed that the velocity and flow profiles are changed when rotation rates change. Futhermore, the flow patterns and temperature profiles of both cases are not axisymmetric even though axisymmetric boundary conditions are used. Several cells appear at no rotation. The cells are formed by the unstable vertical temperature profiles (upper region is colder than lower part) beneath the free surface of the melt. When the temperature profile is combined with density difference (Rayleigh-B nard instability) or surface tension difference (Marangoni-B nard instability) on temperature, cell structures are naturally formed. Both sources of instabilities are coupled to the cell structures in the melt of the Czochralski process. With high rotation rates, the shape of the fluid field is changed to another type of asymmetric profile. Because of the velocity profile, isothermal lines on the plane vertical to the centerline change to elliptic. When the velocity profiles are plotted at the rotating view point, two vortices appear at the both sides of centerline. These vortices seem to be the main reason of the tracer behavior shown in the asymmetric velocity experiment. This profile is quite similar to the profiles created by the baroclinic instability on the rotating annulus. The temperature profiles obtained from the numerical calculations and Fourier transforms of it are quite similar to the results of the experiment. bove esults intend that at least two types of intrinsic instabilities can occur in the melt of Czochralski growing systems. Because the instabilities cause temperature fluctuations in the melt and near the crystal-melt interface, some defects may be generated by them. When the crucible size becomes large, the intensity of the instabilities should increase. Therefore, to produce large single crystals with good quality, the behavior of the intrinsic instabilities in the melt as well as the effects of the instabilities on the defects in the ingot should be studied. As one of the cause of the defects in the large diameter Silicon single crystal grown by the

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.49 no.3
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• pp.51-59
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• 2012

This paper suggests an efficient method which tracks articulated human body modeled with markov network using disparity map derived from stereo images. The conventional methods which only use color information to calculate likelihood for energy function tend to fail when background has same colors with objects or appearances of object are changed during the movement. In this paper, we present a method evaluating likelihood with both disparity information and color information to find human body parts. Since the human body part are cylinder projected to rectangles in 2D image plane, we use the properties of distribution of disparity of those rectangles that do not have discontinuous distribution. In addition to that we suggest a conditional-messages-update that is able to reduce unnecessary message update of belief propagation. Since the message update has comprised over 80% of the whole computation in belief propagation, the conditional-message-update yields 9~45% of improvements of computational time. Furthermore, we also propose an another speed up method called three dimensional dynamic models assumed the body motion is continuous. The experiment results show that the proposed method reduces the computational time as well as it increases tracking accuracy.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.426-432
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• 2008

We introduce a method of rendering a scene lying 3D objects which is like that artist draw on a canvas by brushing. Painting is the art area presenting something created by color and line on 2D plane. We are brushing on billboards on screen space for the 2D brushing effect according to the definition of "Painting". Brushing orientation is haven to rotate for preventing the orientation in the first scene in the case that object or camera are moving. If the brushing isn't rotated, shower-door effect is watched on the scene as undesirable result We present a brushing rotating method for keeping the orientation changing the direction of view and object rigid animation. The brushing direction is computed with Horn's 2D similarity transform by least-square solution. We watched the changing brushing to track the motion of object and view.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1883-1886
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• 2005

In this paper, a decoupled dual servo (DDS) stage for ultra-precision scanning system with large working range is introduced. In general, dual servo systems consist of a fine stage for short range and a coarse stage for long range. The proposed DDS also consists of a $XY\theta$ fine stage for handling and carrying workpieces and one axis coarse stage. Its coarse stage consists of air bearing guide system and a coreless linear motor with force ripple. The fine has four voice coil motors(VCM) as its actuator. According to a VCM's nature, there are no mechanical connections between coils and magnetic circuits. Moreover, VCM doesn't have force ripples due to imperfections of commutation components of linear motor systems - currents and flux densities. However, due to the VCM's mechanical constraints the working range of the fine is about $25mm^2$. To break that hurdle, the coarse stage with linear motors is used to move the fine about 500mm. Because of the above reasons, the proposed DDS can achieve higher precision scanning than other stages with only one servo. With MATLAB's Sequential Quadratic Programming (SQP), the VCMs are optimally designed for the highest force under conditions and constraints such as thermal dissipations due to its coil, its size, and so on. And for their movements without any frictions, guide systems of the DDS are composed of air bearings. To get precisely their positions, a linear scale with 5nm resolution are used for the coarse stage's motion and three plane mirror laser interferometers with 5nm for the fine's $XY\theta$ motions. With them, on scanning the two stages have same trajectories. The control algorithm is named Parallel method. The embodied ultra-precision scanning system has sub 100nm following error and in-positioning stability.

• Journal of Broadcast Engineering
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• v.16 no.4
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• pp.635-646
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• 2011

In distributed video coding, low complexity encoder can be realized by shifting encoder-side complex processes to decoder-side. However, not only motion estimation/compensation processes but also complex LDPC decoding process are imposed to the Wyner-Ziv decoder, therefore decoder-side complexity has been one important issue to improve. LDPC decoding process consists of numerous iterative decoding processes, therefore complexity increases as the number of iteration increases. This iterative LDPC decoding process accounts for more than 60% of whole WZ decoding complexity, therefore it can be said to be a main target for complexity reduction. Previously, HDA (Hard Decision Aided) method is introduced for fast LDPC decoding process. For currently received parity bits, HDA method certainly reduces the complexity of decoding process, however, LDPC decoding process is still performed even with insufficient amount of parity request which cannot lead to successful LDPC decoding. Therefore, we can further reduce complexity by avoiding the decoding process for insufficient parity bits. In this paper, therefore, a parity request estimation method is proposed using bit plane-wise correlation and temporal correlation. Joint usage of HDA method and the proposed method achieves about 72% of complexity reduction in LDPC decoding process, while rate distortion performance is degraded only by -0.0275 dB in BDPSNR.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.2
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• pp.91-99
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• 1985

The acceleration levels and durations of seismic inputs for nuclear power plant design are surveyed. Among those inputs, two artificial acceleration time histories with same acceleration level and duration are selected and their characteristics are studied by calculating response spectra and spectrum intensity. The selected time histories which have the duration of 24 sec. satisfy the design response spectra of US Nuclear Regulatory Commission Regulatory Guide 1. 60. One of the selected time histories is improved to have the duration of 15 sec. without significant changes in the other characteristics. A case study of a plane model with 3 lumped masses is done using three time histories, i.e, two selected and one improved time histories. It is found that the improved curve gives almost the same results as the original one and reduces the computer time by about half, whereas two selected time histories give the results with same trend but much different magnitudes each other. It is claimed, however, that the improved time history is not the optimal one, but very economical in practical applications.

• Journal of Biomedical Engineering Research
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• v.28 no.3
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• pp.397-409
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• 2007

Owing to needs of biomechanical comprehension and analysis to obtain various medical treatment designs which are related with the spine in order to cure and diagnose LBP patients, the FE modeling and nonlinear analysis of lumbosacrum including a partial ilium and iliolumbar ligaments, were carried out. First, we investigated whether the geometrical configuration of vertebrae displayed by DICOM slice files is regular and normal condition. After constructing spinal vertebrae including a partial ilium, a sacrum and five lumbars (from L1 to L5)with anatomical shape reconstructed using softwares such as image modeler and CAD modeler, we added iliolumbar ligaments, lumbar ligaments, discs and facet joints, etc.. And also, we assigned material property and discretized the model using proper finite element types, thus it was completely modeled through the above procedure. For the verification of each segment, average sagittal ROM, average coronal ROM and average transversal ROM under various loading conditions(${\pm}10Nm$), average vertical displacement under compression(400N), ALL(Anterior Longitudinal Ligament) and PLL(Posterior Longitudinal Ligament) force at L12 level, strains of seven ligaments on sagittal plane at L45 level and maximal strain of disc fibers according to various loading conditions at L45 level, etc., they were compared with experimental results. For the verification of multilevel-lumbosacrum spine including partial ilium and iliolumbar ligaments, the cases with and without iliolumbar ligaments were compared with ROM of experiment. The results were obtained from analysis of the verified FE model as follows: I) Iliolumbar ligaments played a stabilizing role as mainly posterior iliolumbar ligaments under flexion and as both posterior and anterior iliolumbar ligaments of one side under lateral bending. 2) The iliolumbar ligaments decreased total ROM of 1-8% in total model according to various motion conditions, which changed facet contact forces of L5S level by approximately 0.8-1.4 times and disc forces of L5S level by approximately 0.8-1.5 times more than casewithout ilioligaments, under various loading conditions. 3) The force of lower discs such as L45 and L5S was bigger than upper discs under flexion, left and right bending and left and right twisting, except extension. 4) It was predicted that strains of posterior ligaments among iliolumbar ligaments would produce the maximum 16% under flexion and the maximum 10% under twisting. 5) It's expected that this present model applies to the development and design of artificial disc, since it was comparatively in agreement with the experimental datum.