• Journal of Power Electronics
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• v.16 no.4
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• pp.1551-1564
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• 2016

The high penetration level of inverter-based distributed generation (DG) power plants is challenging the low-voltage ride-through requirements, especially under unbalanced voltage sags. Recently, a flexible injection of both positive- (PS) and negative-sequence (NS) reactive currents has been suggested for the next generation of grid codes. This can enhance the ancillary services for voltage support at the point of common coupling (PCC). In light of this, considering distant grid faults that occur in a mainly inductive grid, this paper proposes a complete voltage support control scheme for the interface inverters of medium or high-rated DG power plants. The first contribution is the development of a reactive current reference generator combining PS and NS, with a feature to increase the PS voltage and simultaneously decrease the NS voltage, to mitigate voltage imbalance. The second contribution is the design of a voltage support control loop with two flexible PCC voltage set points, which can ensure continuous operation within the limits required in grid codes. In addition, a current saturation strategy is also considered for deep voltage sags to avoid overcurrent protection. Finally, simulation and experimental results are presented to validate the effectiveness of the proposed control scheme.

• Physical Therapy Rehabilitation Science
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• v.4 no.2
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• pp.79-86
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• 2015

Objective: This study was carried out to compare changes in pain, swelling and range of motion (ROM) between the two groups according to physical therapy intervention. Design: Randomized controlled trial. Methods: There were a total of 20 elderly subjects ages 65-75 years old who have been admitted to the hospital for a total knee arthroplasty. After surgery, the experimental group (n=10) carried out quadriceps femoris muscle strengthening exercise, hamstring stretching exercises and gastrocnemius stretching exercise with a physical therapist for 30 minutes and additionally, received ice pack therapy for 20 minutes once a day. The control group (n=10) carried out continuous passive motion for 30 minutes and received ice pack therapy for 20 minutes once a day. The experimental group and control group carried out each intervention program for 2 weeks 3 times a week. The Visual Analogue Scale was used to assess pain, tape measurements were taken to assess swelling, and a steel goniometer was used to assess knee joint ROM. Results: As a result, the experimental group showed a statistically significant decrease in the pain and swelling, and a significant increase in knee flexion ROM after the intervention, compared to the control group (p<0.05). There was a significant improvement in pain, edema, and knee flexion and extension ROM in all subjects after intervention (p<0.05). Conclusions: According the results of this study, exercise in the experimental group is effect on the pain, swelling and ROM for total knee arthroplasty.

• Wind and Structures
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• v.27 no.3
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• pp.175-186
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• 2018

With the continuous increase of span lengths, modern bridges are becoming much more flexible and more prone to flutter under wind excitations. A reasonable probabilistic flutter analysis of long-span bridges involving random and uncertain variables may have to be taken into consideration. This paper presents a method for estimating the reliability index and failure probability due to flutter, which considers the very important variables including the extreme wind velocity at bridge site, damping ratio, mathematical modeling, and flutter derivatives. The Aizhai Bridge in China is selected as an example to demonstrate the numerical procedure for the flutter reliability analysis. In the presented method, the joint probability density function of wind speed and wind direction at the deck level of the bridge is first established. Then, based on the fundamental theories of structural reliability, the reliability index and failure probability due to flutter of the Aizhai Bridge is investigated by applying the Monte Carlo method and the first order reliability method (FORM). The probabilistic flutter analysis can provide a guideline in the design of long-span bridges and the results show that the structural damping and flutter derivatives have significant effects on the flutter reliability, more accurate and reliable data of which is needed.

• Proceedings of the KSR Conference
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• 2006.11a
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• pp.189-197
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• 2006

Maglev using EMS becomes unstable by unexpected big air-gap disturbance. The main causes of the unexpected air-gap disturbance are step-wise rail joint and large distance between rail splices. For the stable operation of the Maglev, the conventional system uses the threshold method, which selects one gap sensor among two gap sensors installed on the magnet to read the gap between magnet and guide rail. But the threshold method with a wide bandwidth makes the discontinuous air-gap signal at the rail joints because of the offset in air gap sensors and/or the step-wise rail joins. Further more, in the case of the one with a narrow bend-width, it makes Maglev system unstable because of frequent alternation. In this paper, a new method using fuzzy rule to reduce air-gap disturbances proposed to improve the stability of Maglev system. It treats the air-gap signal from dual gap sensors effectively to make continuous signal without air gap disturbance. Simulation and experiment results proved that the proposed scheme was effective to reduce air-gap disturbance from dual gap sensors in rail joints.

• Journal of Korean Society of Disaster and Security
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• v.6 no.1
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• pp.29-34
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• 2013

Recently, scale and complexity of disaster are increasing by natural social factor, and there is limit for emergency response by single agency thereby. Therefore, when multi-agency conduct a response for disaster together at the scene, they need preparation for joint response in the advance for systematic mutual cooperation. Preparedness consist of various factors such as planning, securing of Organizations and resource, continuous education and training. This paper focus on emergency response plan and examine the existing state and problem of various plans and manuals. Also submit development way for establishing emergency response plan that had effectiveness through the foreign case analysis.

• Journal of Korean Neurosurgical Society
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• v.50 no.1
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• pp.54-56
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• 2011

Ankylosing spondylitis (AS) is frequently associated with inflammatory lesions of the spine and continuous fatigue stress fractures; however, an association with an intraspinal synovial cyst has not been previously reported. A 55-year-old man with a five year history of AS who presented with back pain and a right radiculopathy was admitted to the hospital. Five years previously, he underwent a percutaneous vertebroplasty for an osteoporotic L1 compression fracture, and was diagnosed with AS at that time. Plain radiographs showed aggravated kyphosis and a stress fracture through the ossified posterior element, below the prior vertebroplasty. Magnetic resonance images revealed a right foraminal cystic lesion at the L2-L3 level with effacement of the nerve root. A 1.6 cm cystic lesion that appeared to arise from the L2-L3 facet joint without direct communication was excised from the L2-L3 foramen. Pathological examination confirmed synovial cyst. The patient's symptoms resolved immediately after surgery except for a mild dysesthesia of the right leg. We report herein a rare case of foraminal synovial cyst associated with AS accompanying posterior element fracture with a review of literature.

• The Korean Journal of Pain
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• v.23 no.4
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• pp.258-261
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• 2010

We report a 66-year-old woman with complex regional pain syndrome (CRPS) 1 treated with combined medical and active physical therapy. She was diagnosed with CRPS 1 following partial shoulder prosthesis due to proximal humerus fracture. Despite continuous medication and physical therapy, there was no improvement in her pain and functional outcome. Her overall pain was decreased by stellate ganglion block 3 times in two weeks conducted during the second month of the follow-up period. Following the ganglion blockades, pain and the other symptoms were decreased intermittently but range of motion (ROM) and functional status were not satisfied as much as expected. After the third month of follow-up, her passive and active ROM of the shoulder joint was increased after application of manipulation under general anesthesia. In conclusion, because CRPS 1 remains one of the most difficult pain syndromes, early diagnosis and treatment are important to have adequate functional results from physical therapy. Manipulation under general anesthesia may be an additional effective treatment tool to obtain functional improvement in some patients diagnosed with CRPS 1.

• Journal of Korean Foot and Ankle Society
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• v.15 no.2
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• pp.97-101
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• 2011

Intravenous Patient Controlled Analgesia (IV PCA0 after general or spinal anesthesia may be a method of postoperative pain control, but side effects such as nausea, vomiting, and sedation occurs in most patients. The following research is based on the ultrasound guided femorosciatic nerve block held on parts below the knee joint operation. Because this anesthesia is held locally on the sciatic nerve with continuous anesthesia performed through perineural catheterization, the complications of nausea, vomiting, and sedation may be reduced while postoperative pain caused by the sciatic nerve is controlled. The following report is held on this experience.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.04a
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• pp.422-430
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• 1998

This paper presents the results of a major parametric study on the collapse cause of the Sungsoo Grand Bridge, a Gerber-type continuous truss bridge, which had collapsed just at the 15th year since opening to traffic. Among the various collapse causes such as poor design, poor welding, poor maintenance, and heavy traffic loads, this study focuses on the collapse cause assessment incorporating the effects of braket and H-beam members right below the expansion joint of the suspended truss. A local FEM analysis using fine shell elements is carrided out for the more precise estimation of stress range of the vertical pin-connected hanger whose fatigue fracture triggered the collapse of the bridge. Both the conventional S-N approach and the Ang-Munse's fatigue reliability method are used for the evaluation of the fatigue life and fatigue failure probability for the assessment based on all the available results of various field and labolatory tests. From these observations, It may be affirmatively stated that the effects of bracket and H-beam members accelerated the fatigue failure, and thus should be regarded as one of major causes that triggered the bridge collapse

• Korean Journal of Applied Biomechanics
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• v.15 no.4
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• pp.131-142
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• 2005

This study was investigated the stability of the AK amputee gait through analysing the variability on kinematic variables between the sound leg and the prosthetic limb. The one male, AK amputee who could walk for himself with his prosthetic limb was participated in this study. Six cameras of the MCU 240 and the QTM(Qualisys Track Manager) software were used for data collecting in this study. The relative angle of both segments was the difference between the absolute angle of the distal segment and the absolute angle of the proximal segment. The coupling angles between the prosthetic limb and the sound leg were caculated on the thigh Flexion/Extension in relative to the shank Flexion/Extension and the shank Flexion/Extension n relative to the foot Flexion/Extension. In order to evaluate the variability of segment and joint angle, C.V. was used, and to evaluate the variability for coupling angles, the Relative motion calculated by vector coding method of the continuous methods was used. As stated, the gait pattern of the prosthetic limb was almost similar gait pattern of the sound leg, but the prosthetic limb showed that the gait pattern of the sound leg and the prosthetic limb were not stable against the sound leg.