• Research in Community and Public Health Nursing
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• v.30 no.1
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• pp.47-56
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• 2019

Purpose: This study was performed to evaluate effects of a stim-up matt walking exercise program on balance and gait of the frail elderly. Methods: A total of 37 elderly people recruited from S city were randomly assigned to the experimental group (n=22) and control group (n=15). The stim-up matt walking exercise program was offered twice a week for 8 weeks. Data were analyzed by SPSS 21.0. Results: The dynamic balance ability Timed Up and Go test of the experimental group was significantly faster than that of the control group (t=21.72, p<.001). The static balance ability open-eye standing test (t=44.15, p<.001) and close-eye standing test (t=9.01, p=.005) also showed increase in effects of the experimental group. In the walking ability, gait cycle (t=2.48, p=.018), cadence (t=-2.21, p=.034) and gait speed (t=-2.78, p=.009), positive effects were on. However, no statistically significant differences were found in stride length and double support. At the ankle joint range left ankle plantar flexion (t=3.92, p<.001) and left ankle dorsal flexion (t=4.51, p<.001) were higher in the experimental group than in the control group, and also right ankle plantar flexion (t=2.79, p=.008) and right ankle dorsal flexion (t=2.92, p=.006) increased in the experimental group. Conclusion: The significance of this study is that the stim-up matt walking exercise program for the frail elderly proves to be useful for improving balance and walking.

• Journal of Korean Society of Steel Construction
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• v.18 no.1
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• pp.53-58
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• 2006

The aim of this paper is to verify the dynamics stability of the continuous PSC Box bridges on the high-speed Kyoung-bu railway when a high-sped train runs through it. An experimental study was carried out to investigate the dynamic behaviors of the PSC Box railway bridge, which had ben designed based on dynamic design criteria. As a result, it was determined that PSC Box railway bridges possess enough dynamics stability for use by high-speed trains. According to the result of a field test (dynamics measuring analysis) that was conducted, an application of the natural frequency of train speed and the adjustment of the bridge's span length will allow one to come up with a more economical and suitable bridge design. Furthermore, it was found that the continuous control of the bridge's dynamic behavior and the bridge's maintena nce require the recording of data. The results of this study are very important in evaluating the structural stability of high-speed line bridges.

• Physical Therapy Rehabilitation Science
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• v.9 no.2
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• pp.105-112
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• 2020

Objective: To investigate the effects of training using a trunk control robot (TCR) system combined with conventional therapy (CT) on balance and gait abilities in persons with chronic stroke. Design: Two-group pretest-posttest design. Methods: Thirty-five subjects with chronic stroke were randomly assigned to either the TCR group (n=17) or the trunk extension-training (TET) group (n=18). Both groups performed CT for 30 minutes, after which the TCR group performed TCR training and the TET group performed trunk extension training for 20 minutes. Both groups performed the therapeutic interventions 3 days per week for 6 weeks. Balance ability was evaluated using the Berg Balance Scale (BBS), and the Timed Up-and-Go (TUG) test. Gait ability was measured using the 10 m Walk Test (10MWT) and the NeuroCom Smart Balance Master. Results: TCR group showed significant improvements in static balance (weight bearing) and dynamic balance (weight shifting speed, weight shifting direction, BBS, and TUG), 10MWT, gait speed, and step width (p<0.05); step length was not significant. The TET group showed a significant partial improvement of dynamic balance (weight shifting speed, weight shifting direction, BBS, and 10MWT (p<0.05), but the improvements in static balance, TUG, gait speed, and step width and step length was not significant. Additionally, significant differences in static balance, dynamic balance (weight shifting speed, weight shifting direction, BBS, and TUG), 10MWT, gait speed, and step width were detected between groups (p<0.05). Conclusions: TCR training combined with CT is effective in improving static and dynamic balance, as well as gait abilities in persons with chronic stroke.

• Journal of the Korean Society for Railway
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• v.16 no.1
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• pp.7-13
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• 2013

A scaled version of a roller rig is developed to demonstrate the dynamic characteristics of a railway vehicle for academic purposes. This rig is designed based on Jaschinski's similarity law. It is scaled to 1/10 of actual size and allows 9-DOF motion to examine the up and down vibration of a train set. The test rig consists of three sub-hardware components: (i) a driving roller mechanism with a three-phase AC motor and an inverter, (ii) a bogie structure with first and second suspensions, and (iii) the vehicle body. The motor of the rig is capable of 3,600rpm, allowing the test to simulate a vehicle up to a maximum speed of 400Km/hr. Because bearings and joints are properly connected to the sub-structures, various motion analyses, such as a lateral, pitching, and yawing motion, are allowed. The slip motion between the rail and the wheel set is also monitored by several sensors mounted in the rig. After the construction of the hardware, an experiment is conducted to obtain the natural frequencies of the dynamic behavior of the specimen. First, the test rig is run and data are collected from six sets of accelerometers. Then, a numerical analysis of the model based on the ADAMS program is derived. Finally, the measurement data of the first three fundamental frequencies are compared to the analytical result and the validation of the test rig is conducted. The results show that the developed roller rig provides good accuracy in simulating the dynamic behavior of the vehicle motion. Although the roller rig designed in this paper is intended for academia, it can easily be implemented as part of a dynamic experiment of a bogie and a vehicle body for a high-speed train as part of the research efforts in this area.

• Journal of the Korean Society of Physical Medicine
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• v.15 no.4
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• pp.47-54
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• 2020

PURPOSE: This study compared two different techniques of treadmill gait training, and evaluated the outcomes on gait and respiratory function in patients with hemiplegic stroke. METHODS: This was a single-blinded, randomized, controlled, comparative study, enrolling a total of 21 stroke patients in a rehabilitation hospital. Subjects were randomly assigned to either the treadmill walking training group with gradual speed increase (GSI group, n = 10), or treadmill walking training group with random speed changing (RSC group, n = 11). All participants performed 60 min of comprehensive rehabilitation therapy (5 × / week for 6 weeks). In additional, each group received either GSI or RSC treadmill walking training for 20 min (5 × / week for 6 weeks, total 30 sessions). Gait and respiratory function were measured before and after the 6-week training. RESULTS: Both groups showed significant improvements in the 10-m walking test, 6-minute walking test, timed up and go test, forced vital capacity (FVC), forced expiratory volume in 1 second, and maximal voluntary ventilation after training (p < .05). The GSI group showed a significantly greater increase in the FVC than the RSC group (+14.8 L vs. +12.5 L, p < .05). CONCLUSION: Both training methods can be effective for improving the walking and respiratory functions of stroke patients. However, our results indicate that treadmill walking training with gradual speed increase might be a more effective method for improving the respiratory function (FVC) than treadmill walking training with random speed changing.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.4
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• pp.347-355
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• 2016

In this study, a new designed propeller was applied on 24 ton class squid jigging vessel to reduce of fuel consumption. The selected squid jigging boat was under construction at the shipyard to determine the resistance of the hull through the model experiment. The propeller design was carried out by using the experimental data and ITTC procedures. Sea trials were performed by measuring the speed and the horsepower required by the condition of five power levels of engine load, namely 70%, 80%, 90%, MCR and maximum engine power. The speed and delivered horse power were compared between the conventional propeller and the new design propeller. Delivered horse power by installing the new propeller takes 90% engine load at start-up conducted by decreased 9.06%. The measuring speed is increased up to the 0.6 knots in the low-speed range to high range. This study showed that only the design and installation of a new propeller can improve the propulsion efficiency of the boats; furthermore, reduce fuel costs can be achieved at the same time by improving the increased cruising speed.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.274-280
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• 2006

The study is to analyze dynamo test results for various commercial pads in order to verify the performance of brake disk with CV-NCM cast iron. The developed brake disk will apply to 200 km/h tilting trains that is being developed as one part of project for speed-up on Korean existing railroad. The test program is made out suitably for braking condition and performance of test equipment by referring UIC 541-3. Two kinds of resin pad and one kind of foreign sintered pad suitable for 200 km/h trains are used as various commercial pad for the dynamo test. The data aquisition for the maximum and smallest temperature, hot spot, etc. on disk and pad is performed by using the thermocouples and thermal imaging cameras. From this research, we obtained braking characteristics between CV-NCM cast iron disk and pad of various material and will be utilized usefully as basis data of performance optimization of developing sintered pad.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.2
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• pp.203-212
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• 2002

Active magnetic hearings allow much high surface speed than conventional ball bearings and therefore greatly suitable for high speed cutting. This paper describes a design and test of an active magnetic bearing system with 16-pole radial magnets. The spindle is originally designed for a CNC lathe and driven by outer motor with 5.5 kW power and maximum speed 10,000 rpm. Considering static load condition and geometric restrictions, radial magnet is designed 16-pole type for smaller outer diameter of the spindle system. Dynamic system characteristics such as natural frequency, critical speed, stiffness, damping and system stabilities are simulated with a rigid rotor model including direct feedback controller. The designed spindle system is realized with digital PIDD controller to compensate phase lag of PWM amplifier and magnet coils. With levitation and step response experiment the control system characteristics are tested, and the spindle is rotated up to 10,000 rpm stab1y.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.232-237
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• 2007

The deformation of polymers under high loading-rate conditions will be a governing factor to be considered in their impact-resistant applications such as protective shields and transparent armor. In this paper, the deformation and fracture behaviors of polymeric materials such as PE, PC and PEEK have been investigated by Taylor Impact tests. Taylor cylinder impact tests and high speed photography are introduced to examine the deformation behavior under dynamic loading condition. 20 mm air gun was used to perform the impact experiments. Cylindrical projectiles have been impacted onto a hardened steel anvil at a velocity ranging from 100 to $350\;ms^{-1}.$ Along the barrel line, a photo-sensor which measures the speed of the projectile, four digital cameras which has shutter speed of 1/917,000sec and a rigid anvil were set up. After impact experiments, the shapes of projectiles and images taken using high speed cameras were analysed. Depending on materials adopted, they showed a variety in deformation and fracture behaviors.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.05a
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• pp.45-51
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• 2000

Investigators who study on combustion in the cylinders of reciprocating piston type internal combustion engines have been encountered embarrassments due to the difficulties of adjusting specific parameter without interfacing other parameters such as cylinder wall temperature composition of gas in the cylinder existence of cylinder lubricant etc. Rapid compression-expansion machine the position and speed of piston of which are able to be controlled by means of a system controlled electrically and speed of piston of which are able to be controlled by means of a system controlled electrically and actuated hydraulically could be utilized as one of the most preferable countermeasures against those difficulties. Several units of rapid compression-expansion machines were developed but the speed up of frequency of piston movement still is the problem to be improved to cope with actual speed of internal combustion engines. Authors designed and manufactured a new rapid compression-expansion machine electrically controlled hydraulically actuated and computer programed and then examined the performance of one. Results of a set of experiments revealed acquirements of certain improvement of frequency of piston movement preserving the stability of system response and reproducing accurate compression ratio of cylinder those are the key function for the in-cylinder combustion experiments of internal combustion engines.