• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.3
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• pp.51-56
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• 2001

In this paper, the effect of magnetic field on corona discharge phenomena was experimentally investigated in the needle-plate electrode geometry. Needle-plate geometry discharge system with magnetic field at a right angle to the electric field was made. The corona discharge characteristics with magnetic field were investigated and compared with the corona characteristics without magnetic field in atmospheric pressure. As a result, in case of positive DC corona discharge with magnetic field, corona discharge zone was significantly wider, corona current was lower, and breakdown voltage was higher than those without magnetic field. However, in case of negative DC corona discharge with magnetic field, corona current was slightly higher and breakdown voltage was lower than those without magnetic field. It is thought that this result is due to cyclotron motion of charged particles such as electron and ion by magnetic field.

• Journal of ILASS-Korea
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• v.25 no.1
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• pp.8-14
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• 2020

Recently, 1-D model-based engine development using virtual engine system is getting more attention than experimental-based engine development due to the advantages in time and cost. Injection rate profile is the one of the main parameters that determine the start and end of combustion. Therefore, it is essential to set up a sophisticated model to accurately predict the injection rate as starting point of virtual engine system. In this research, procedure of 1-D model setup based on AMESim is introduced to predict the dynamic behavior and injection rate of diesel injector. As a first step, detailed 3D cross-sectional drawing of the injector was achieved, which can be done with help of precision measurement system. Then an approximate AMESim model was provided based on the 3D drawing, which is composed of three part such as solenoid part, control chamber part and needle and nozzle orifice part. However, validation results in terms of total injection quantity showed some errors over the acceptable level. Therefore, experimental work including needle movement visualization, solenoid part analysis and flow characteristics of injector part was performed together to provide more accuracy of 1-D model. Finally, 1-D model with the accuracy of less than 10% of error compared with experimental result in terms of injection quantity and injection rate shape under normal temperature and single injection condition was established. Further work considering fuel temperature and multiple injection will be performed.

• Journal of Physiology & Pathology in Korean Medicine
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• v.32 no.5
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• pp.315-320
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• 2018

The purpose of this study is to investigate reasearch trend of acupuncture treatment on shoulder impingement syndrome. This study investigated the recent studies about acupuncture treatment for shoulder impingement syndrome via searching Korean and foreign electronic databases(Research Information Services, National Digital Science Library, Oriental Medicine Advanced Searching Integated Services, PubMed, China National Knowledge Infrastructure). The search term was searched by combining 'shoulder impingement sydrome', 'subacrominal pain', 'acupuncture', 'needle therapy', and was limited to the articles published from 2005 to 2017. 14 studies were found to be analyzed according to the type of study, the number of cases, the type of treatment, the instruments for assessment and published year. 14 studies were published since 2005, 6 case reports, 8 randomized controlled trials. In the treatment of shoulder impingement syndrome, treatments such as acupuncture, acupotomy, pharmacopuncture, laser acupuncture, combined treatment of exercise and rehabilitation were performed. Visual analogue scale(VAS), range of motion(ROM) and various questionnaires were used as primary assessments. In each study, acupuncture treatment was reported to have a significant effect in the pain, range of motion and disability of shoulder impingement syndrome. In order to ensure objective evidence on acupuncture treatment, large scale case reports and randomized controlled trials should be continued.

• Journal of ILASS-Korea
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• v.11 no.3
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• pp.131-139
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• 2006

An experimental study was performed to investigate the liquid breakup and atomization characteristics in electrohydrodynamic atomization according to the changing of experimental parameters such as nozzle size, fluid flow, and electrical intensity. An original electrohydrodynamic atomizer equipment was designed and manufactured for the analysis of spray visualization and the exploration of relationship between applied power and the behavior of liquid atomization. The image processing technique by using the back-illumination method was applied to visualize the distilled liquid breakup process and to examine the variation of the droplet size distribution. The results show that the spray modes of electrohydrodynamic atomization are closelyconnected by the strength of the electric stresses at the surface of the liquid film and the kinetic energy of the liquid jet leaving the needle tip.

• Archives of Plastic Surgery
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• v.33 no.1
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• pp.120-123
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• 2006

Spontaneous extensor pollicis longus tendon rupture is commonly caused by attrition of the tendon from trauma or inflammatory processes. We experienced a patient with extensor pollicis longus tendon rupture after steroid injection, in which the rupture may have been caused by the effects of steroid itself as well as direct damage from the needle. A 51-year-old woman complained of inability to extend her right thumb at the first metacarpophalangal & interphalangeal joint level. The patient had a history of local steroid injection into the dorsal & radial side of wrist on two occations, and had no history of trauma or rheumatologic disease. After a physical examination of the patient, we decided to explore the wrist. The patient agreed with operation. Intraoperatively, an incision was made into the wrist and the proximal and distal ends of the ruptured extensor pollicis longus tendon were identified. The defect between the proximal and the distal end was measured to approach 8cm, and a palmaris longus tendon graft was performed. After three months of rehabilitation, the first metacarpophalangal & interphalangeal joint recovered the normal range of motion. Steroid injection has been widely used in various musculoskeletal disorders such as rheumatoid arthritis and osteoarthritis. However, inadvertent steroid injection into the extra or intra articular spaces may lead to tendon rupture. Steroids reduce tensile strength by decreasing tenocyte activity and collagen synthesis. Also, the physical effect of direct needle-stick injury into the mesotenon and blood vessels around the tendon may cause damage. In addition, hematoma and edema may increase pressure around the tendon and compromise blood supply, leading to tendon degeneration and subsequent rupture. When injecting steroid into an articular area, all physicians should have a complete understanding of the surrounding anatomy and always keep in mind the hazards of such procedures.

• Journal of radiological science and technology
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• v.33 no.4
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• pp.379-386
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• 2010

This study evaluated the motion of tumors during the entire period of therapy and the accuracy of radiosurgery among forty eight lung tumor patients who were underwent radiosurgery using the CyberKnife Synchrony Respiratory Tracking System. The motion of lung tumor was measured by the coordinates of a gold acupuncture needle inserted into the tumor or the area around the tumor using the CyberKnife image guided system. Then the accuracy of radiosurgery was evaluated based on the error of correlation computed with the motion tracking system. The lung tumor motion is Cranio-Caudal direction by an average of $2.63{\pm}1.87\;mm$, moved left-right direction by $1.13{\pm}0.71\;mm$, and anterior-posterior direction by $1.74{\pm}1.16\;mm$. The degree of rotational movement was $1.66{\pm}1.66^{\circ}$ on X axis, $1.20{\pm}0.97^{\circ}$ on Y axis, and $1.18{\pm}0.73^{\circ}$ on Z axis. The vector of translation movement was measured to be $3.78{\pm}2.00\;mm$ on the average. The results show that directions of Cranio-Caudal(p < 0.001), anterior-posterior direction(p < 0.029), and three dimensional vector value(p < 0.002) showed statistical significance, because the lower side of tumor showed more intensive movement compared to the upper side of tumor. The radiosurgery was carried out by compensating the motion of tumor after accurate investigation of the correlation error with the average of $0.95{\pm}0.62\;mm$ during the lung tumor radiosurgery with the CyberKnife Synchrony Respiratory Tracking System.

• Journal of Korean Orthopaedic Sports Medicine
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• v.4 no.1
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• pp.55-59
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• 2005

Purpose: To evaluate the drainage effect of silk suture material following aspiration of the bursa as an early treatment of chronic prepatellar bursitis. Materials and Methods: Twelve cases, which have over two weeks of history and over one year of follow-up, were investigated. The average duration of follow-up was 18.3 months. The average symptom duration before introduction into this study was 2.2 months. With an aseptic technique, the aspiration of the bursa was done with spinal needle or injection needle and syringe and then the insertion of silk suture material through the aspiration needle was performed. Over one year follow-up, recurrence, infection, pain, and limitation of range of motion were investigated by telephone interview. Results: Redness around the insertion site of silk suture material was found in all cases, but there was no development of active infection in eleven cases. At five days after procedure, a supprative infection was developed in one case. The results were considered satisfactory in 92% of cases and the average duration of treatment is 14.5 days. Conclusion: The drainage with silk suture material following aspiration of the bursa is effective and less invasive method in the early treatment of chronic prepatellar bursitis.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.1 no.1
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• pp.6-9
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• 2008

Purpose: To investigate the effectiveness of injection therapy in the treatment of subacromial bursitis. Materials and Methods: A total of 38 patients with sonographic confirmation of subacromial bursitis were recruited into this study. The shoulder abduction range of motion and visual analog scale (VAS) were compared before injections and 3 wks after the completion of injections. Results: The shoulder range of abduction before injection was $77.89{\pm}14.17$ degrees and improved to $148.68{\pm}13.39$ degrees 3 wks after the injection treatments (P<0.05). VAS before injection was $6.8{\pm}1.4$ and improved to $1.4{\pm}0.8$ 3 wks after the injection treatments (P<0.05). Conclusions: Ultrasound may be used as an adjuvant tool in guiding the needle accurately into the inflamed subacromial bursa. The ultrasound-guided injection technique can result in significant improvement in shoulder abduction range of motion in treating patients with subacromial bursitis.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.1
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• pp.106-111
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• 2024

A triboelectric nanogenerator is a promising energy harvester operated by the combined mechanism of electrostatic induction and contact electrification. It has attracting attention as eco-friendly and sustainable energy generators by harvesting wasting mechanical energies. However, the power generated in the natural environment is accompanied by low frequencies, so that the output power under such input conditions is normally insufficient amount for a variety of industrial applications. In this study, we introduce a non-contact rotational triboelectric nanogenerator using pedaling and gear systems (called by P-TENG), which has a mechanism that produces high power by using rack gear and pinion gear when a large force by a pedal is given. We design the system can rotate the shaft to which the rotor is connected through the conversion of vertical motion to rotational motion between the rack gear and the pinion gear. Furthermore, the system controls the one directional rotation due to the engagement rotation of the two pinion gears and the one-way needle roller bearing. The TENG with a 2 mm gap between the rotor and the stator produces about the power of 200 ㎼ and turns on 82 LEDs under the condition of 800 rpm. We expect that P-TENG can be used in a variety of applications such as operating portable electronics or sterilizing contaminated water.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.1
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• pp.116-122
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• 1988

Interfacial shear stresses have been determined for countercurrent stratified flow of air and water in a nearly-horizontal rectangular channel, based upon measurements of pressure drop, gas velocity profiles and mean film thickness. A dimensionless correlation for the interfacial friction factor has been developed as a function of the gas and liquid Reynolds numbers. Equivalent surface roughnesses for the interfacial friction factor have been calculated using the Nikuradse correlation and have been compared with the intensity of the wave height fluctuation on the interface. The results show that the interfacial shear stress is mainly affected by turbulent mixing near the interface due to the wave motion rather than by the roughened surface.