• Journal of muscle and joint health
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• v.19 no.1
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• pp.16-26
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• 2012

Purpose: The purpose of this study was to investigate the effects of lumbar stabilization exercise on balance ability in patients with adolescent idiopathic scoliosis. Methods: This study was one group pretest-posttest design. Twenty young idiopathic scoliosis patients were recruited for this study. They had the lumbar stabilization exercise program for 40 minutes a day, three times per week for 3 weeks. The lumbar trunk muscle endurance test and clinical balance tests (functional forward reach, functional lateral reach, Fukuda 50-stepping, one leg standing with eyes open and eyes closed) were measured before and after the lumbar stabilization exercise. Results: There were significant differences between pre-and post-test in absolute value of the difference between right and left lateral reach, distance of Fukud 50-stepping and one leg standing on the each side with eyes closed(p<.05). The results showed that the lumbar trunk muscle endurance significantly increased(p<.05). Conclusion: In this study indicated that the lumbar stabilization exercise was effective on balance ability and lumbar trunk muscle endurance in patients with young idiopathic scoliosis.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.223-224
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• 2009

A wireless ad hoc network is a decentralized wireless network. The network is ad hoc because each node is willing to forward data for other nodes, and so the determination of which nodes forward data is made dynamically based on the network connectivity. In this paper, we proposed new route maintenance algorithm to improve the efficiency and effective in order to reach destination node. In this algorithm we improve existing route maintenance in Dynamic Source Routing protocol, to improve the algorithm we make a new message we call Emergency Message (EMM). The emergency message used by the node moved to provide information of fault detection.

• Journal of the Korean Society of Safety
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• v.29 no.6
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• pp.104-110
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• 2014

The Han River is the only waterway in Korea where estuary is not blocked by dykes so that tidal water is flowing in and out through the tidal reach. The extreme tidal range in the Yellow Sea causes an intense flood current, stretching over horizontal extents of tens of kilometers into the rivers. To elucidate the flow reversal by discharge conditions and transient tidal level in the Han river, numerical simulations were conducted under 7 boundary conditions for two days with 10 minute time step. As the flow conditions changed from low discharge and high tidal difference to high discharge and low tidal difference, the flow reversals became weaker and the velocity of forward flow direction became higher due to the increased flow momentums and decreased tidal differences. In the case of normal flow, the maximum reverse velocity was 0.4 m/s, which was equivalent to the maximum forward velocity. In addition, the pattern of the development and decay of forward and reverse flow was presented.

• The Journal of Korean Physical Therapy
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• v.21 no.4
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• pp.9-16
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• 2009

Purpose: This study was done to assess the effect of changes in forward head posture (FHP), neck mobility and headache clinical parameters on episodic tension-type headache (ETTH) and chronic tension-type headache (CTTH) who did craniocervial exercises. Methods: Twelve CTTH subjects and twelve ETTH subjects were studied. Side-view pictures of subjects were taken in both sitting and standing positions, in order to assess FHP by measuring the craniovertebral angle. Cervical range of motion (CROM) was employed to measure cervical mobility. A headache diary was kept to assess headache intensity, frequency, and duration. All subjects did three types of craniocervical exercise over 8 weeks. Measurements were done at pre-treatment, and at 4 and 8 weeks post-treatment. Results: Forward head posture and headache-related clinical parameters showed a significant improvement after craniocervical exercise (p<0.05). Flexion/extension and left/right rotation of CROM was significantly increased after the intervention (p<0.05), whereas changes in left/right bending did not reach statistical significance. Conclusion: This study indicates that craniocervical exercise may be effective in the management of tension-type headache.

• Korea-Australia Rheology Journal
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• v.19 no.4
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• pp.211-219
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• 2007

Here we demonstrate complex transient behavior of viscoelastic liquid described numerically with the Leonov model in straight and contraction channel flow domains. Finite element and implicit Euler time integration methods are employed for spatial discretization and time marching. In order to stabilize the computational procedure, the tensor-logarithmic formulation of the constitutive equation with SUPG and DEVSS algorithms is implemented. For completeness of numerical formulation, the so called traction boundaries are assigned for flow inlet and outlet boundaries. At the inlet, finite traction force in the flow direction with stress free condition is allocated whereas the traction free boundary is assigned at the outlet. The numerical result has illustrated severe forward-backward fluctuations of overall flow rate in inertial straight channel flow ultimately followed by steady state of forward flow. When the flow reversal occurs, the flow patterns exhibit quite complicated time variation of streamlines. In the inertialess flow, it takes much more time to reach the steady state in the contraction flow than in the straight pipe flow. Even in the inertialess case during startup contraction flow, quite distinctly altering flow patterns with the lapse of time have been observed such as appearing and vanishing of lip vortices, coexistence of multiple vortices at the contraction comer and their merging into one.

• Smart Structures and Systems
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• v.18 no.5
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• pp.931-953
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• 2016

In this paper, the effects of mass eccentricity of superstructure as well as stiffness eccentricity of isolators on the amplification of seismic responses of base-isolated structures are investigated by using mathematical near-fault pulse models. Superstructures with 3, 6 and 9 stories and aspect ratios equal to 1, 2 and 3 are mounted on a reasonable variety of Triple Concave Friction Pendulum (TCFP) bearings considering different period and damping ratio. Three-dimensional linear superstructure mounted on nonlinear isolators are subjected to simplified pulses including fling step and forward directivity while various pulse period ($T_p$) and Peak Ground Velocity (PGV) amounts as two crucial parameters of these pulses are scrutinized. Maximum isolator displacement and base shear as well as peak superstructure acceleration and drift are selected as the main engineering demand parameters. The results indicate that the torsional intensification of different demand parameters caused by superstructure mass eccentricity is more significant than isolator stiffness eccentricity. The torsion due to mass eccentricity has intensified the base shear of asymmetric 6-story model 2.55 times comparing to symmetric one. In similar circumstances, the isolator displacement and roof acceleration are increased 49 and 116 percent respectively in the presence of mass eccentricity. Furthermore, it is demonstrated that torsional effects of mass eccentricity can force the drift to reach the allowable limit of ASCE 7 standard in the presence of forward directivity pulses.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.77-82
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• 2006

Automatic vessel collision-avoidance systems have been studied in the fields of artificial intelligence and navigation for decades. And to facilitate automatic collision-avoidance decision-making in two-vessel-encounter situation, several expert and fuzzy expert systems have been developed. However, none of them can negotiate with each other as seafarers usually do when they intend to make a more economic overall plan of collision avoidance in the COLREGS-COST-HIGH situations where collision avoidance following the International Regulations for Preventing Collisions at Sea(COLREGS) costs too much. Automatic Identification System(AIS) makes data communication between two vessels possible, and negotiation methods can be used to optimize vessel collision avoidance. In this paper, a negotiation framework is put forward to enable vessels to negotiate to optimize collision avoidance in the COLREGS-COST-HIGH situations at open sea. A vessel vector space is defined and therewith a cost model is put forward to evaluate the cost of collision-avoidance actions. Negotiations between a give-way vessel and a stand-on vessel and between two give-way vessels are considered respectively to reach overall low cost agreements. With the framework proposed in this paper, two vessels involved in a COLREGS-COST-HIGH situation can negotiate with each other to get a more economic overall plan of collision avoidance than that suggested by the traditional collision-avoidance expert systems.

• Journal of Hydrospace Technology
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• v.1 no.1
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• pp.29-40
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• 1995

This paper describes the procedure to predict steady and unsteady performances of a contrarotating propeller(CRP) by a mixed formulation of the boundary value problem(BVP) far the flow around a CRP. The blade BVP is treated by a classical vortex lattice method, whereas the hub BVP is solved by a potential-based panel method. Blades and trailing wakes are represented by a vortex and/or source lattice system, and hubs are represented by normal dipole and source distributions. Both forward and aft propellers are solved simultaneously, thus treating the interaction effect without iteration. The unsteady performance is computed directly in time domain. The new numerical procedure requires a large amount of storage and computing time, which is however no longer a limit in a modern computer system. Sample computations show that the steady performance compares very well with the experiments. The predicted unsteady behavior shows that the dominant harmonics of the total forces are multiples of not only the number of blades of the forward and aft propellers but also the product of both blade numbers. The magnitude of the latter harmonics, present also in uniform oncoming flow, may reach abort 50% of the mean torque for the aft propeller, which in turn may cause a serious vibration problem in the complicated contrarotating shafting system.

• The Journal of Korean Physical Therapy
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• v.34 no.5
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• pp.218-223
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• 2022

Purpose: This study sought to identify the effects of an insole applied for the flexible flat-foot condition on dynamic balance and ankle muscle activities during the Y-balance test (YBT). Methods: Thirteen flexible flat-footed adults and an equal number of normal-footed adults were enrolled. The dynamic balance of the subjects was measured using the YBT, which is a reach test. While they were reaching forward with their foot, the percentage maximum voluntary isometric contraction (MVIC) of the tibialis anterior, peroneus longus and medial and lateral gastrocnemius were measured and analyzed. The flat-footed group then applied the ready-made insoles and underwent the YBT again. A comparison of the distance and muscle activity was conducted using YBT, not only between the flat-footed and control group, but also between the flat-footed group before and after the application of the insole. Results: Between the groups, the anterior reach distance in the flat-footed group was significantly lower, but there were no significant differences observed in the posteromedial and posterolateral directions. With the insole, the reach distance of the flat-footed group was significantly increased in the anterior and posterolateral direction compared to the control group. With the insole, the lateral gastrocnemius activity significantly decreased compared to trials without the insole in the flat-footed group, but there were no significant differences in the other muscles. Conclusion: The insole for flat-footed subjects can maintain the medial arch of the foot, and it may help enhance functional and mechanical dynamic balance in people with flat feet.

• Physical Therapy Korea
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• v.7 no.1
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• pp.32-37
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• 2000

The purpose of this study is to determine the effects of exercise training on the strength and balance ability of the elderly. The results of this study are: 1) After 8 weeks exercise training, knee muscle strength showed a significant increment. 2) After exercise training, forward functional reach and balance index of KAT 2000 showed a significant increment. Results indicate that strengthening exercise can result in improved muscle strength and balance in the elderly. Further studies are required to show long-term effects of exercise training on the elderly.