• 한국압력기기공학회 논문집
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• 제7권2호
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• pp.7-13
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• 2011

Turbine journal bearings are designed to support the weight of the rotors on a hydrodynamic oil film and to provide dynamic stability to the rotor system. The life time of journal bearings is infinite theoretically because the journal bearings are separated from the shaft journal by oil film. But poor design, assembly, operation and maintenance can cause problems to the journal bearings. The FMEA(Failure Mode and Effects Analysis) results of the journal bearings show that frequent maintenance of the journal bearings can cause failures and reduction of the bearing life. Therefore, the maintenance periods and history of the journal bearings with the bearing FMEA results are reviewed in order to establish the optimized maintenance period of the journal bearing for the nuclear power plants. Consequently it is necessary to maintain a best condition of lubrication system, reject time-based maintenance and perform the condition-based maintenance of journal bearings in order to maintain optimum condition of the journal bearing.

• 한국소음진동공학회논문집
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• 제20권8호
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• pp.717-726
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• 2010

For the application into a 1 kWh flywheel energy storage system(FESS), this paper presents the design scheme of radial and axial hybrid magnetic bearings which use bias fluxes generated by permanent magnets. In particular, the axial hybrid magnetic bearing is newly proposed in this paper, in which a permanent magnet is arranged in axial direction so that it can support the rotor weight as well as provide a bias flux for axial magnetic bearing. Such hybrid magnetic bearings consume very low power, compared with conventional electromagnetic bearings. In this paper, to stably support a 140 kg flywheel rotor without contact, design process is explained in detail, and magnetic circuit analysis and three-dimensional finite element analysis are carried out to determine the design parameters and predict the performance of the magnetic bearings.

• 한국소음진동공학회논문집
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• 제17권9호
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• pp.847-852
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• 2007

Design aspects of a bearing casing system of a power plant are mainly focused on the strength and weight of itself to have a more stable system. Since the rotor speed often passes through the critical speed region when the operation begins, the relation between the rotating frequency of the rotor and natural frequency of the casing is very important for a prevention of resonance. However, harmonic components above the rotating frequency have often been overlooked the design for the resonance avoidance. In this paper, it is revealed that resonance vibration is generated when the natural frequency of a bearing casing is close to the one of harmonics of basic rotating frequency(1x), and as a consequence, sensing qualify of seismoprobes attached to the bearing casing structure can be seriously damaged. In order to reduce the resonance vibration, some stiffeners are added to the casing structures. Significant reduction in the magnitude of vibration corresponding to 2x harmonic of basic rotating frequency is observed from both FE analysis and experiment.

• Geomechanics and Engineering
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• 제5권4호
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• pp.363-377
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• 2013

Any structure constructed on the earth is supported by the underlying soil. Foundation is an interfacing element between superstructure and the underlying soil that transmits the loads supported by the foundation including its self weight. Foundation design requires evaluation of safe bearing capacity along with both immediate and long term settlements. Weak and compressible soils are subjected to problems related to bearing capacity and settlement. The conventional method of design of footing requires sufficient safety against failure and the settlement must be kept within the allowable limit. These requirements are dependent on the bearing capacity of soil. Thus, the estimation of load carrying capacity of footing is the most important step in the design of foundation. A number of theoretical approaches, in-situ tests and laboratory model tests are available to find out the bearing capacity of footings. The reliability of any theory can be demonstrated by comparing it with the experimental results. Results from laboratory model tests on square footings resting on sand are presented in this paper. The variation of bearing capacity of sand below a model plate footing of square shape with variation in size, depth and the effect of permissible settlement are evaluated. A steel tank of size $900mm{\times}1200mm{\times}1000mm$ is used for conducting model tests. Bearing capacity factor $N_{\gamma}$ is evaluated and is compared with Terzaghi, Meyerhof, Hansen and Vesic's $N_{\gamma}$ values. From the experimental investigations it is found that, as the depth of sand cushion below the footing ($D_{sc}$) increases, ultimate bearing capacity and settlement values show an increasing trend up to a certain depth of sand cushion.

• 한국도로학회:학술대회논문집
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• 한국도로학회 2004년도 학술발표회 논문집
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• pp.199-202
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• 2004

• Journal of Acupuncture Research
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• 제31권2호
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• pp.11-19
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• 2014

Objectives : This study was aimed to determine which pharmacopuncture was effective in relieving pain in standard pain model, acute grade 3 ankle sprain rat model. Methods : Percentage changes of weight bearing ratio(WBR), as pain indicator, were measured after anti-inflammation, neutro Eohyul, Hwangryunhaedock-decoction pharmacopuncture were injected to Guheo ($GB_{40}$). Results : In three kinds of pharmacopuncture, neutro Eohyul and Hwangryunhaedock-decoction pharmacopuncture represented more effect in percentage changes of WBR than surgical(non treatment), needling group. Conclusions : Comparing of pharmacopuncture in grade 3 ankle sprain rat model, these results provide basis to select pharmacopuncture in sprain disease. Furthermore, mechanism of pharmacopuncture's analgesia, anti-inflammation should be progressed.

• Physical Therapy Rehabilitation Science
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• 제6권4호
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• pp.159-163
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• 2017

Objective: Persons with stroke have a tendency to exhibit asymmetric weight-bearing during sit-to-stand because due to the attempt to support themselves with the non-paretic foot. However, there are few devices that can assist with sit-to-stand (STS) performance. This study was designed to investigate the use of the elastic band with rings (EBR) in improving weight-bearing effectively in persons with stroke during STS training. Design: Cross-sectional study. Methods: Thirteen stroke survivors participated in the study. An EBR was applied onto the patient during STS activity. The foot pressure was measured before and after wearing the EBR, with a 5-minute rest period between measurements. Subjects were asked to perform each test twice with and without the EBR. Bilateral feet pressures were measured with standing posture being divided into the forward and backward aspects. The foot contact pressure during STS activity was measured with the CONFORMat System. Results: With EBR, the forward pressure of the affected foot significantly increased while the less-affected forward foot pressure significantly decreased (p=0.015 and p=0.023, respectively). The backward foot pressure did not differ significantly in the two limbs, and there was no difference with and without the EBR in terms of the total pressure of the affected foot. There was a significant difference with and without the EBR in the total pressure of the less-affected foot (p<0.05). Conclusions: STS training with the EBR has been shown to improve weight-bearing of both feet while decreasing the total pressure of the less-affected foot in stroke survivors. Therefore, we suggest that the EBR is a useful tool for STS training for persons with stroke in the clinic.

• The Journal of Korean Physical Therapy
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• 제17권4호
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• pp.457-467
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• 2005

Physiotherapyists frequently use manipulative therapy technique to treat dysfunctionand pain resulting from ankle sprain. Despite the high prevalence of lateral ankle ligament injuries, few studies are available indicating any physical associations with the development of lateral ankle ligament injuries, or information of treatment for lateral ankle ligament injuries. To investigate the effect of passive joint mobilization, the anteroposterior glide on the talus, on increasing weight-bearing dorsiflexion, single support time and VAS. Sixty lateral ankle ligament injuries (grade I and grade II) aged between 17 and 27 years (mean age 21) were recruited. Subjects were randomly assigned to 1 of 2 treatment groups. The control group received a protocol of rest, ice, compression, and elevation (RICE) and massage. The experimental group received the anteroposterior mobilization, using a force that avoided incurring any increase in pain, in addition to the RICE protocol. Subjects in both groups were treated every second day for a maximum of 2 weeks or until the discharge criteria were met, and all subjects were given a home program of continued RICE application. Outcomes were measured after each treatment. The results showed that the experimental group than the control group. Weight-bearing dorsiflexion (F=7.640, P<0.05), single support time (F=85.532, P<0.05) and VAS (F=10.610, P<0.050). Between-groups differences were observed as; experimental group is increased weight-bearing dorsiflexion, single support time and reduced VAS.

• 대한족부족관절학회지
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• 제13권2호
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• pp.156-161
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• 2009

Purpose: The fracture of talus has critical complications and results in various clinical outcomes. The purpose of this study is to evaluate clinical outcome and influence on involvement of ankle and subtalar joint. Materials and Methods: From December 1999 to December 2008, a total of 66 fractures and dislocations of talus was treated with minimal 9 months follow up period. Ankle-hindfoot scale of the American Orthopedic Foot & Ankle Society (AOFAS) was used to evaluate the clinical outcome. The complications and sequential radiologic findings were also analyzed. Results: There were 28 neck fractures, 11 lateral process fractures, 10 body fractures, 7 osteochondral fractures, 4 posteromedial tubercle fractures and 4 medial process fractures. In 38 cases, there were concomitant injuries. Ipsilateral ankle fracture, which found in 19 cases, was most common. The surgical treatment was performed in 36 cases. Mean AOFAS score was 85.5 (range, 72 to 96). In 13 of 47 cases, one or more fracture lines involving weight bearing surface were confirmed. The involvement of ankle or subtalar joint had resulted in unsatisfied outcome. Complications were developed as follows, post-traumatic arthritis in 8 cases, avascular necrosis in 3 cases, and deep infection in 2 cases. Conclusion: The involvement of ankle or subtalar joint in fractures of talus seemed to be common and to impact the clinical outcome. Meticulous consideration about that will be positively necessary.

• 한국전문물리치료학회지
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• 제27권3호
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• pp.191-198
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• 2020

Background: Stroke patients experience multiple dysfunctions that include motor and sensory impairments. Therefore, new intervention methods require a gradational approach depending on functional levels of a stroke patient's activity and should include cognition treatment to allow for a patient's active participation in rehabilitation. Objects: This study investigates the effect of integrated revision of electrical sensory stimulation, which stimulates somatosensory and action observation training, which is synchronized cognition intervention method on stroke patients' functions. Methods: Twenty-one stroke patients were randomized into two groups. The two groups underwent twenty minutes of intervention five times a week for three weeks. This study used an electromyogram to evaluate symmetric muscle activation of lower extremities and muscle onset time when performing sit to stand before and after intervention. A weight-bearing ratio was used to evaluate the weight-bearing of the affected side in a sit to standing. To evaluate sit to stand performance ability, this study performed five timed sit to stand tests. Results: The two groups both showed statistically significant improvement in muscle onset time of lower extremity, static balance ability in a standing position, and sit to stand performance after the intervention (p < 0.05). In addition, the action observation and synchronized electrical sensory stimulation group showed significant improvement in symmetric muscle activation of lower extremities and weight-bearing ratio of the affected side (p < 0.05). Conclusion: action observation and synchronized electrical sensory stimulation (AOT with ESS) can have positive effects on a stroke patient's sit to stand performance, and the intervention method that provides integrated AOT with ESS can be used as new nervous system intervention program.