• 대한물리의학회지
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• 제14권1호
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• pp.131-138
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• 2019

PURPOSE: This study examined the effects on muscle activation and ankle instability following sudden ankle inversion of the closed kinetic chain exercise using visual feedback to evaluate chronic ankle instability in adult males. METHODS: In this study, 28 subjects with chronic ankle instability were recruited and randomly divided into a closed kinetic chain exercise using a visual feedback group(n=13) and an open kinetic chain exercise group(n=15). Each group underwent 30 minutes of exercise three times a week for 8 weeks. The electromyographic(EMG) values of the rectus femoris, biceps femoris, tibialis anterior, peroneus longus, peroneus brevis, and lateral gastrocnemius muscles were measured to analyze muscle activity. The Cumberland ankle instability tool(CAIT) was used to measure ankle instability. RESULTS: Both groups showed improvements in tibialis anterior, peroneus longus and CAIT score(p<.05). In the experimental group, there were significant improvements in the rectus femoris, biceps femoris, and lateral gastrocnemius muscle activation(p<.05). CONCLUSION: The results suggest that closed kinetic chain exercise using visual feedback can be a useful treatment method for patients with chronic ankle instability.

• 국제물리치료학회지
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• 제11권4호
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• pp.2212-2220
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• 2020

Background: Repetitive damage to the ankle joint causes chronic ankle instability, and studies comparing the effects of exercise in open and closed chains as a treatment method are very rare. Objectives: To investigate the effects of open and closed kinetic exercises on muscle activity and dynamic balance of ankle joint in adults with chronic ankle instability. Design: Single-blind randomized controlled trial. Methods: The selected 30 subjects are randomly divided into open kinetic chain exercise experimental group (EGI, n=10), closed kinetic chain exercise experimental group (EGII, n=10), and stretching control group (CG, n=10). Open and closed kinetic exercises lasted 30 minutes three times a week for six weeks and stretching exercises performed four actions for 20 seconds and five sets. The measurement tools using surface electromyography to measure muscle activity in the ankle joint. The dynamic balance of the ankle was evaluated using the Y-Balance test. Results: Following the intervention, closed and open kinetic chain exercise group showed significant difference in tibialis anterior and gastrocnemius muscle activity and dynamic balance (P<.05). However, no significant difference in tibialis anterior and gastrocnemius muscle activity and dynamic balance between closed and open kinetic chain exercise group (P<.05). Conclusion: This study provides evidence that closed and open kinetic chain exercise can be presented as an effective exercise for the muscle activity of ankle muscle and dynamic balance of the subject with chronic ankle instability.

• Journal of Korean Neurosurgical Society
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• 제45권1호
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• pp.24-31
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• 2009

Objective : To investigate the effectiveness of radiographic parameters on segmental instability in the lumbar spine using Kinetic magnetic resonance imaging (MRI). Methods : Segmental motion, defined as excessive (more than 3 mm) translational motion from flexion to extension, was investigated in 309 subjects (927 segments) using Kinetic MRI. Radiographic parameters which can help indicate segmental instability include disc degeneration (DD), facet joint osteoarthritis (FJO), and ligament flavum hypertrophy (LFH). These three radiographic parameters were simultaneously evaluated, and the combinations corresponding to significant segmental instability at each level were determined. Results : The overall incidence of segmental instability was 10.5% at L3-L4, 16.5% at L4-L5, and 7.3% at L5-S1. DD and LFH at L3-L4 and FJO and LFH at L4-L5 were individually associated with segmental instability (p<0.05). At L4-L5, the following combinations had a higher incidence of segmental instability (p<0.05) when compared to other segments : (1) Grade IV DD with grade 3 FJO, (2) Grade 2 or 3 FJO with the presence of LFH, and (3) Grade IV DD with the presence of LFH. At L5-S1, the group with Grade III disc and Grade 3 FJO had a higher incidence of segmental instability than the group with Grade I or II DD and Grade 1 FJO. Conclusion : This study showed that the presences of either Grade IV DD or grade 3 FJO with LFH at L4-L5 were good indicators for segmental instability. Therefore, using these parameters simultaneously in patients with segmental instability would be useful for determining candidacy for surgical treatment.

• 한국연소학회지
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• 제7권1호
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• pp.23-30
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• 2002

Instability of oblique detonation waves (ODW) at off-attaching condition was investigated through a series of numerical simulations. Two-dimensional wedge of finite length was considered in $H_2/O_2/N_2$ mixtures at superdetonative condition. Numerical simulation was carried out with a compressible fluid dynamics code and a detailed hydrogen-oxygen combustion mechanism. Present result reveals that there is a chemical kinetic limit of the ODW detachment, in addition to the theoretical limit predicted by Rankine-Hugoniot theory with equilibrium chemistry. Result also presents that ODW still attaches at a wedge as an oblique shock-induced flame showing periodically unstable motion, if the Rankine-Hugoniot limit of detachment is satisfied but the chemical kinetic limit is not. Mechanism of the periodic instability is considered as interactions of shock and reaction waves coupled with chemical kinetic effects. From the investigation of characteristic chemical time, condition of the periodic instability is identified as follows; at the detaching condition of the Rankine-Hugoniot theory, (1) flow residence time is smaller than the chemical characteristic time, behind the detached shock wave with heat addition, (2) flow residence time should be greater than the chemical characteristic time, behind an oblique shock wave without heat addition.

• Journal of Welding and Joining
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• 제25권3호
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• pp.37-44
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• 2007

Mechanical and thermomechanical properties of the bulk metallic glass (BMG) are so unique that the deformation behavior is largely dependent on the temperature and the strain rate. Impacting behavior of NiTiZrSiSn bulk metallic glass powder during kinetic spraying was investigated in this study. Considering the impact behavior of the BMG, the kinetic spraying system was modified and attached the powder preheating system to make the transition from the inhomogeneous deformation to the homogeneous deformation of impacting BMG particle easy BMG splat formation is considered from the viewpoint of the adiabatic shear instability. It is suggested that the impact behavior of bulk metallic glass particle is determined by the competition between fracture and deformation. The bonding of the impacting NiTiZrSiSn bulk amorphous particle was primarily caused by the temperature-dependent deformation and fracture (local liquid formation) behavior.

• The Journal of Korean Physical Therapy
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• 제17권3호
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• pp.297-310
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• 2005

Open kinetic chain exercise has lost favour in rehabilitation after cruciate ligament reconstruction due to concerns that this exercise is harmful to the graft and will be less effective in improving function. Therefore rehabilitation has focused over the past decade on closed kinetic chain exercise. Open kinetic chain and closed kinetic chain exercises were compared for their effects on proprioception, muscle strength and knee instability in the early period of cruciate ligament reconstruction rehabilitation. The study subjects were 14 patients in 28weeks from cruciate reconstruction surgery(11 male, 3 female; mean age = 44.36 years). Closed kinetic chain exercise group used ball, balance pad and air cushion, to perform weightbearing exercises and the open kinetic chain exercise group used elastic rope and N-K table, to perform non-weightbearing exercises. Between tests, subjects trained 5 times per week for 2 weeks. Statistical analysis was by Wilcoxon signed rank test and Mann Whitney U test. In result, this study shows that both open and closed kinetic chain exercise programs lead to an improved muscle strength and Lysholm score. But there was no improvement in proprioception at both exercises. Closed versus open kinetic chain exercise in early period of rehabilitation after cruciate ligament reconstruction surgery do not differ in their effects on knee proprioception, muscle strength and instability. But the effect of closed kinetic chain exercises was showed more improvement than open kinetic chain exercises between pre-post exercises. Therefore further study is required to assess effect of both groups in more long period.

• 한국세라믹학회지
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• 제49권1호
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• pp.29-36
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• 2012

In many applications of functional oxides originally homogeneous materials are exposed to gradients in the chemical potential of oxygen. Prominent examples are solid oxide fuel cells (SOFCs) or oxygen permeation membranes (OPMs). Other thermodynamic potential gradients are gradients of electrical potential, temperature or uni-axial pressure. The applied gradients act as generalized thermodynamic forces and induce directed fluxes of the mobile components. These fluxes may lead to three basic degradation phenomena of the materials, which are kinetic demixing, kinetic decomposition, and morphological instabilities.

• 한국연소학회지
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• 제18권2호
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• pp.42-50
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• 2013

Linear stability analysis of radiating counterflow diffusion flames is numerically conducted to examine the instability characteristics of cellular patterns. Lewis number is assumed to be 0.5 to consider diffusional-thermal instability. Near kinetic limit extinction regime, growth rates of disturbances always have real eigen-values and neutral stability condition of planar disturbances perfectly falls into quasi-steady extinction. Cellular instability of disturbance with transverse direction occurs just before steady extinction. However, near radiative limit extinction regime, the eigenvalues are complex and pulsating instability of planar disturbances appears prior to steady extinction. Cellular instability occurs before the onset of planar pulsating instability, which means the extension of flammability.

• 한국운동역학회지
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• 제32권1호
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• pp.9-16
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• 2022

Objective: The purpose of this study was to investigate how the chronic ankle instability affects postural control during forward jump landing. Method: 20 women with chronic ankle instability (age: 21.7 ± 1.6 yrs, height: 162.1 ± 3.7 cm, weight: 52.2 ± 5.8 kg) and 20 healthy adult women (age: 21.8 ± 1.6 yrs, height: 161.9 ± 4.4 cm, weight: 52.9 ± 7.2 kg) participated in this study. For the forward jump participants were instructed to stand on two legs at a distance of 40% of their body height from the center of force plate. Participants were jump forward over a 15 cm hurdle to the force plate and land on their non-dominant or affected leg. Kinetic and kinematic data were obtained using 8 motion capture cameras and 1 force plates and joint angle, vertical ground reaction force and center of pressure. All statistical analyses were using SPSS 25.0 program. The differences in variables between the two groups were compared through an independent sample t-test, and the significance level was to p < .05. Results: In the hip and knee joint angle, the CAI group showed a smaller flexion angle than the control group, and the knee joint valgus angle was significantly larger. In the case of ankle joint, the CAI group showed a large inversion angle at all events. In the kinetic variables, the vGRF was significantly greater in the CAI group than control group at IC and mGRF. In COP Y, the CAI group showed a lateral shifted center of pressure. Conclusion: Our results indicated that chronic ankle instability decreases the flexion angle of the hip and knee joint, increases the valgus angle of the knee joint, and increases the inversion angle of the ankle joint during landing. In addition, an increase in the maximum vertical ground reaction force and a lateral shifted center of pressure were observed. This suggests that chronic ankle instability increases the risk of non-contact knee injury as well as the risk of lateral ankle sprain during forward jump landing.

• 대한화학회지
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• 제65권6호
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• pp.419-432
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• 2021

According to the transition state (TS) theory, Gaussian software and Yao and Lin (YL) method, the thermodynamics and kinetic data respectively were calculated, and anharmonic effect was considered for related reactions of NO₃. The methods of calculating and fitting kinetic and thermodynamics parameters were provided by least square method and related equations in this paper. Notably, the fitted E of Arrhenius equation was close to the calculated barrier of related reaction by QCISD(T) method. Therefore, the kinetic fitting result can well express the physical meaning of E in Arrhenius equation. Besides, the conversion process and the reaction mechanism of NO₃ were researched. For NO₃, it seemed that its instability results from its easy reaction with other substances rather than the decompose reaction of itself.