• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.187-189
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• 1997

Thermal and electrical breakdown phenomena in XLPE insulator of power cable were investigated. At high temperature the polymeric insulator was thermally deteriorated. Under the magnified high electric field, electrical tree was initiated at the sharp tip of needle electrode which was inserted to simulate the defects and impurities such as void, crack, metallic particles, dusts, and so on.

• 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.

• The Korean Journal of Pain
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• v.8 no.1
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• pp.74-77
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• 1995

Upper thoracic sympathectomy is valuable for patients with vascular occlusive disease and other painful upper extremity diseases. We performed 10 upper thoracic sympahthectomies by percutaneous radiofrequency destruction in painful disorder of upper extremity. Patients were supine and the needle was inserted paratracheally under C-arm fluoroscope. The second and third thoracic sympathetic gangla were destructed by radiofrequency lesion generator. Each lesion was made with a tip temperature of $90^{\circ}C$, 90 seconds. Good to excellent results were achieved in all patients without any adverse effect. Seven patients revealed complete sympatholytic effect and other three patients were showen signs of partial sympathetic block. Two patients were persisted sympatholytic effect for 18month in and other 5 patients were persisted sympatholytic effect at present (follow up period: mean 5.8 mon). Percutaneous radiofrequency upper thoracic sympathectomy with anterior paratracheal approach is an effective and a safe method.

• The Korean Journal of Pain
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• v.2 no.2
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• pp.181-188
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• 1989

Neurolytic splanchnic nerve block is an effective method for the relief of pain of upper abdominal cancer. Nine cases of intractable upper abdominal cancer pain were treated by splanchnic nerve block with absolute alcohol (25 ml) at the pain clinic of Kangdong Sacred Heart Hospital, Hallym University, during a 19 month period from March, 1988 to September, 1989. The group included six patients with stomach cancer, two patients with pancreatic cancer, and one patient with hepatobiliary cancer. We used fluoroscopy in all cases of alcohol spianchnic nerve block to determine both, the position of the needle tip, and the spread of the neurolytic solution. Of the 9 patients, 6 patients had excellent pain relief, and 3 patients who had combined upper abdominal and lower back pain had relieved upper abdominal pain only, but remaining lower back pain. Of the 9 patients', 5 patients had excellent pain relief through the patients remaining life (1-2 months) in which follow up was possible.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.4
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• pp.99-106
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• 2010

A piezo-driven injector was applied with a purpose to evaluate the effect of induced voltage on spray characteristics. For this, injection rate, macroscopic imaging, ambient gas entrainment and particle sizing were carried out. It was shown that initial slope of injection rate was steeper as induced voltage increased, while slope of injection rate became mostly constant with fully opened needle. From macroscopoic imaging, longer spray tip penetration was produced with higher induced voltage. Moreover, wider spray angle was detected in the early stage of spray development, when higher induced voltage was applied. Ambient air entrainment rate was increased and particle size was reduced with higher induced voltage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.285-288
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• 1998

Ultrasonic signal characteristics related with the growth of electrical trees in epoxy resin are examined under 67[Hz] ac voltage application along with a CCD camera and PD current method. The ultrasonic sensor with a resonant frequency of 200[Hz] supported by a mechanical spring is attached directly to the lower-side of plane electrode. The magnitude of Partial discharge and count rate of ultrasonic signals have been measured according to the tree growth from a needle tip in an epoxy sample.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1436-1437
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• 2007

This paper presents the experimental results of the dielectric characteristics with temperature changes under highly non-uniform electric field in $SF_6$ gas. The impulse preliminary breakdown developments were investigated by the measurement of predischarge current and breakdown voltage. As a result, the first stremer corona is initiated at the tip of needle electrode, and bridges the test gap. Also the first stremer corona onset and breakdown voltages the negative polarity was much higher than that in the positive polarity in same temperature. In addition, the varition of temperature have a little effect on the positive polarity. On the other hand, in some cases negative polarity corona onset and breakdown voltages increased with increasing a high temperature.

• Journal of Institute of Convergence Technology
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• v.1 no.1
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• pp.48-51
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• 2011

Transdermal drug delivery device is a method of drug delivery through the skin. Skin has a very large area, so it is attractive route to drug delivery. When drug delivery through the skin, microneedle has a advantage that painless, constant drug deliver and penetration efficient; nevertheless the cost is expensive because fabrication process need a particular equipment and not suitable in mass production. This study shows microneedle fabrication process using convergence of general MEMS process and dicing process that can make 3-D sharp microneedle tip and this fabrication process suitable for mass production.

• Restorative Dentistry and Endodontics
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• v.33 no.6
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• pp.499-506
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• 2008

The purpose of this study was to compare the push-out strength of a fiber post cemented with various resin cements. Newly extracted 36 human mandibular premolars which had single root canal were selected and their crown portions were removed. The root canal was instrumented using $PROTAPER^{TM}$ system and obturated using continuous wave technique. In each root, a 9-mm deep post space was prepared. #2 translucent fiber post (DT Light post, Bisco Inc., Schaumburg, IL, U.S.A.) was cemented using injection technique with Uni-dose needle tip (Bisco) and six different resin cements. The tested resin cements were Duo-Link (Bisco Inc., Schaumburg, IL, U.S.A.), Variolink II (Ivoclar-Vivadent AG, Schann, Liechtenstein), Panavia F (Kuraray Medical Inc., Okayama, Japan), Multilink Automix (Ivoclar-Vivadent AG, Schann, Liechtenstein), RelyX Unicem (3M ESPE Dental Products, St. Paul, MN, U.S.A.), and Maxcem (Kerr Co., CA, U.S.A.). After storage in distilled water for 24 hours, each root was transversally sectioned into approximately 1-mm thick sections. This procedure resulted in 6 serial sections per root. Push-out test wasperformed using a universal testing machine (EZ Test, Shimadzu Co.) with a crosshead speed of 1 mm/min. The data were analyzed with one-way ANOVA and Tukey HSD (p=0.05). The push-out strength of the groups which cemented fiber post with Panavia F and Multilink Automix were lower than those of the other groups. But, there were no statistically significant difference among groups at a probability level of 0.05.

• The Korean Journal of Pain
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• v.25 no.3
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• pp.155-160
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• 2012

Background: We have developed an intradiscal pulsed radiofrequency (Disc PRF) technique, using Diskit $II^{(R)}$ needles (NeuroTherm, Wilmington, MA, USA), as a minimally invasive treatment option for chronic discogenic low back pain (LBP). The purpose of this study was to compare the representative outcomes of Disc PRF and Intradiscal Electrothermal Therapy (IDET) in terms of pain relief and reduction of disability. Methods: Thirty-one patients with chronic discogenic LBP who underwent either Disc PRF (n = 15) or IDET (n = 16) were enrolled in the study. A Diskit $II^{(R)}$ needle (15-cm length, 20-gauge needle with a 20-mm active tip) was placed centrally in the disc. PRF was applied for 15 min at a setting of $5{\times}50$ ms/s and 60 V. The pain intensity score on a 0-10 numeric rating scale (NRS) and the Roland-Morris Disability Questionnaire (RMDQ) were assessed pretreatment and at 1, 3, and 6 months post-treatment. Results: The mean NRS was significantly improved from $7.2{\pm}0.6$ pretreatment to$2.5{\pm}0.9$ in the Disc PRF group, and from $7.5{\pm}1.0$ to $1.7{\pm}1.5$ in the IDET group, at the 6-month follow-up. The mean RMDQ also showed significant improvement in both the Disc PRF group and the IDET group at the 6-month follow-up. There were no significant differences in the pretreatment NRS and RMDQ scores between the groups. Conclusions: Disc PRF appears to be an alternative to IDET as a safe, minimally invasive treatment option for patients with chronic discogenic LBP.