• Journal of Korean Neurosurgical Society
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• v.58 no.2
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• pp.144-146
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• 2015

Postdural punctural headache (PDPH) following spinal anesthesia is due to intracranial hypotension caused by cerebrospinal fluid (CSF) leakage, and it is occasionally accompanied by an intracranial hematoma. To the best of our knowledge, an intracranial chronic subdural hematoma (CSDH) presenting with an intractable headache after a cervical epidural steroid injection (ESI) has not been reported. A 39-year-old woman without any history of trauma underwent a cervical ESI for a herniated nucleus pulposus at the C5-6 level. One month later, she presented with a severe headache that was not relieved by analgesic medication, which changed in character from being positional to non-positional during the preceding month. Brain magnetic resonance imaging revealed a CSDH along the left convexity. Emergency burr-hole drainage was performed and the headache abated. This report indicates that an intracranial CSDH should be considered a possible complication after ESI. In addition, the event of an intractable and changing PDPH after ESI suggests further evaluation for diagnosis of an intracranial hematoma.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.190-193
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• 2001

ZnO varistors have been widely used to protect power system and electronic system against overvoltages based on their excellent nonlinearity. In order to increase their protection capability, the fracture and protection technologies of arresters have to study according to their applications, namely ImA DC voltage, leakage currents, impulse residual voltages, withstanding capability to impulse surge, and energy absorption capability. ZnO varistors which have nonlinear current-voltage characteristic name a number of failure mechanism when ZnO elements absorb surge energies. Failure mode by thermal stress and Pin hole are among the most common failure mechanism at the high current surge current. In this study, the fracture mechaism of power arresters are introduced and protection technologies are researched. In particular the effect of thermal stress by surge currents to ZnO elements and methods against arc surge energy through withstand structure design of arrester are discussed.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.687-690
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• 2003

Experimental results are presented for gate oxide degradation and its effect on device parameters under negative and positive bias stress conditions using NMOSFET's with 3 nm gate oxide. The degradation mechanisms are highly dependent on stress conditions. For negative gate voltage, both hole- and electron-trapping are found to dominate the reliability of gate oxide. However, with changing gate voltage polarity, the degradation becomes dominated by electron trapping. Statistical parameter variations as well as the "OFF" leakage current depend on those charge trapping. Our results therefore show that Si or O bond breakage by electron can be another origin of the investigated gate oxide degradation.gradation.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.232-238
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• 1997

In this paper, a theoretical method is presented to design a hydraulic control valve system that consist of an important component in the hydraulic snubber. The hydraulic snubber is used essentially to support the piping systems at power plants. To calculate the force due to pressure drop and flow rate in the valve orifice and by-pass hole, Bernoulli equation is used. The Reynolds equation are numerically analyzed in the clearance gap between the valve cone and valve seat to estimate the friction force and leakage flow rate. Based on the detailed theoretical data, we developed successfully the hydraulic snubber for power plants.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.648-651
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• 2008

Numerical calculations are performed to simulate the film cooling effect of turbine blade tip with squealer rim. Because of high temperature of inside rim, squealer rim is damaged easily. Therefore many various cooling systems were used. The calculations are based on 100,000 Reynolds number in linear cascade model. A blade has 2% tip clearance and 8.4% rim height. The axial chord length and turning angle is 237mm, 126$^{\circ}$. Numerical calculations are performed without and with film cooling. In a film cooling in the cavity, hot spots of cavity were cooled effectively. However hot spots of suction side rim still remains. The CFD results show that the circulation flow in cavity of squealer tip affects the temperature rise of squealer rim. To maintain the blade integrity and avoid the excessive hot spot of blade, rearrangement of cooling hole is needed.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.172-175
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• 2008

In the last five years, 45 people died and 104 were wounded because of carbon monoxide poisoning accident. CO poisoning accident is higher than any other gas accident in the rate of deaths/incidents. Most of these CO poisoning accidents were caused by defective exhaust tube in the old gas boiler and multi-use facility. In this study, the spread of CO gas released from leakage hole of exhaust tube was analyzed by computational flow modeling and concentration measuring test. CO gas leaked form exhaust tube in a building was highest concentrated near the ceiling and formed the circular currents along the walls. Through these experiments and simulation, the reasonable installation location of CO alarm was made certain and suggested.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.322.2-322.2
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• 2014

Lighting emitting diodes of n-ZnO/MQW/p-GaN structure are fabricated and investigated. To realize this LED structure, n-ZnO/MQW/p-GaN are grown by MOCVD. At several bias voltages, blue-green light is emitted from the ZnO mesa edge. However, the emission is restricted near the mesa edge. It is seen that the hole current does not spread well. It is because conductivity of p-GaN is extremely small. The break down voltage of the device is small compared to conventional InGaN/GaN LEDs. It is seen that ZnO columnar grain boundaries act as leakage current paths and non-radiative recombination center.

• Journal of the korean academy of Pediatric Dentistry
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• v.4 no.1
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• pp.35-38
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• 1977

The study was performed to evaluate effects of Conservative treatment between amalgam filling and stainless steel crown. The selected subjects for this study was 350 children who have amalgam filling or stainless steel crown. The obtained results are as followings. 1. In amalgam filling teeth, 120 teeth (60.0%) showed marginal leakage, 57 teeth (28.5%) showed fracture of filling material and 28 teeth (14.0%) teeth showed periapical lesion. 2. In crowned teeth, 6 teeth (3.0%) showed hole on the surface of crown, 29 teeth (14.5%) showed avulsion of crown and 10 teeth (5.0%) showed periapical lesion. 3. After 12 months from examining date, 69 teeth (34.5%) showed sound condition in amalgam filling teeth and 155 teeth (75.2%) showed sound condition in crowned teeth.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.6
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• pp.43-49
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• 1997

Tungsten poycide has studied gate oxide reliability and dielectric strength charactristics as the composition of gate electrode which applied submicron on CMOS and MOS device for optimizing gate electrode resistivity. The gate oxide reliability has been tested using the TDDB(time dependent dielectric breakdwon) and SCTDDB (stepped current TDDB) and corelation between polysilicon and WSi$_{2}$ layer. iN the case of high intrinsic reliability and good breakdown chracteristics on polysilicon, confirmed that tungsten polycide layer is a better reliabilify properities than polysilicon layer. Also, hole trap is detected on the polysilicon structure meanwhile electron trap is detected on polycide structure. In the case of electron trap, the WSi$_{2}$ layer is larger interface trap genration than polysilicon on large POCL$_{3}$ doping time and high POCL$_{3}$ doping temperature condition. WSi$_{2}$ layer's leakage current is less than 1 order and dielectric strength is a larger than 2MV/cm.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.3
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• pp.559-565
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• 2015

To defend against information leakage or malware inflow by USB memory, security technologies such as copy protection and device control have being researched and developed. However, countermeasure are insufficient despite being recognized as a fatal security-hole for BadUSB presented at the Black Hat Security Conference 2014. To solve this problem, the countermeasures for BadUSB vulnerability are proposed.