• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.1
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• pp.33-36
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• 2004

Amorphous GaN film was deposited using a laser ablation of the highly densified GaN target. Through the surface morphological and compositional analysis of films deposited under various laser energies and Ar gas pressures, the film deposited under the pressure of 10 Pa were found to be amorphous GaN with the smooth surface. In particular, the film at 200 mJ/pulse showed the enhanced crystallinity and stoichiometric composition, compared with those of the films at relatively lower laser energy. The strong band-gap emission at 2.8 eV was observed from amorphous GaN film in the room temperature photoluminescence spectra, showing the highest efficiency in the film at 200 mJ/pulse under 10 Pa.

• Journal of Cerebrovascular and Endovascular Neurosurgery
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• v.26 no.1
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• pp.46-50
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• 2024

Objective: Diagnostic cerebral angiograms (DCAs) are widely used in neurosurgery due to their high sensitivity and specificity to diagnose and characterize pathology using ionizing radiation. Eliminating unnecessary radiation is critical to reduce risk to patients, providers, and health care staff. We investigated if reducing pulse and frame rates during routine DCAs would decrease radiation burden without compromising image quality. Methods: We performed a retrospective review of prospectively acquired data after implementing a quality improvement protocol in which pulse rate and frame rate were reduced from 15 p/s to 7.5 p/s and 7.5 f/s to 4.0 f/s respectively. Radiation doses and exposures were calculated. Two endovascular neurosurgeons reviewed randomly selected angiograms of both doses and blindly assessed their quality. Results: A total of 40 consecutive angiograms were retrospectively analyzed, 20 prior to the protocol change and 20 after. After the intervention, radiation dose, radiation per run, total exposure, and exposure per run were all significantly decreased even after adjustment for BMI (all p<0.05). On multivariable analysis, we identified a 46% decrease in total radiation dose and 39% decrease in exposure without compromising image quality or procedure time. Conclusions: We demonstrated that for routine DCAs, pulse rate of 7.5 with a frame rate of 4.0 is sufficient to obtain diagnostic information without compromising image quality or elongating procedure time. In the interest of patient, provider, and health care staff safety, we strongly encourage all interventionalists to be cognizant of radiation usage to avoid unnecessary radiation exposure and consequential health risks.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.719-720
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• 2004

A multi-megawatt long pulse ion source (LPIS) of neutral beam injector was developed for the KSTAR. Beam extraction experiments of the LPIS were carried out at the neutral beam test stand (NBTS). Design requirements for the ion source were 120 kV/65 A deuterium beam and a 300 s pulse length. A maximum ion density of $9.1310^{11}$ $cm^{-3}$ was measured by using electric probes, and an optimum arc efficiency of 0.46 A/kW was estimated with ion saturation current of the probes, arc power, and total beam area. An arcing problem, caused by the structural defect of decelerating grid supporter, in the third gap was solved by the blocking of backstream ion particles, originated from the plasma in the neutralizer duct, through the unnecessary spaces on the side of grid supporter. A maximum drain power of 1.5 MW (i.e. 70 kV/21 A) with hydrogen was measured for a pulse duration of 0.5 s. Optimum beam perveance was ranged from 0.75 to 0.85. An improved design of accelerator for the effective control of beam particle trajectory should provide higher beam perveance.

• Computers and Concrete
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• v.20 no.4
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• pp.491-502
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• 2017

In this research, the application of ultrasonic pulse velocity (UPV) test as a nondestructive method for estimating some of the mechanical and dynamic properties of reactive powder concrete (RPC) containing steel and polyvinyl alcohol (PVA) fibers, as well as their combination was explored. In doing so, ten different mix designs were prepared in 19 experimental groups of specimens containing three different volume contents of steel fibers (i.e., 1, 2, and 3 %) and PVA fibers (i.e., 0.25, 0.5, and 0.75 %), as well as hybrid fibers (i.e., 0.25-0.75, 0.5-0.5, and 0.75-0.25 %). The specimens in these groups were prepared under the two curing regimes of normal and heat treatment. Moreover, the UPV test results were employed to estimate the compressive strength, dynamic modulus, shear modulus, and Poisson's ratio of the RPC concrete and to investigate the quality level of the used concrete. At the end, the effect of the specimen shape and in fact the measuring distance length on the UPV results was explored. The results of this research suggest that the steel fiber-containing RPC specimens demonstrate the highest level of ultrasonic pulse velocity as well as the highest values of the mechanical and dynamic properties. Moreover, heat treatment has a positive effect on the density, UPV, dynamic modulus, Poisson's ratio, and compressive strength of the RPC specimens, whereas it leads to a negligible increase or decrease in the shear modulus and static modulus of elasticity. Furthermore, the specimen shape affects the UPV of fiber-lacking specimens while negligibly affecting that of fiber-reinforced specimens.

• Electrical & Electronic Materials
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• v.4 no.1
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• pp.73-81
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• 1991

본 논문은 가교폴리에틸렌중의 공간전하 분포를 직접 측정이 가능한 Laser-유기압력파법에 의하여 조사하였다. 그 결과 XLPE는 폴리에틸렌보다 전자주입이 쉽게 됨을 알았으며 그때의 시료내의 공간전하 분포를 측정할 수 있었다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.204-206
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• 2022

eLoran 시스템에서 보다 높은 정확도로 시각 및 위치 정보를 제공하기 위해 별도의 데이터 채널인 Loran Data Channel (LDC)를 사용한다. LDC 메시지는 기존의 8개의 Loran 펄스 중 항법에 사용하지 않는 3-8번째 펄스의 전송시각을 변조하여 송출하는 Eurofix 방식과 9번째 추가 펄스를 이용해 데이터를 변조하는 9^th 펄스 방식으로 변조될 수 있다. 본 논문에서는 eLoran 송신국에서 송출하는 LDC 메시지의 변조방법에 따른 수신 성능을 분석한다. 인천에서 운영 중인 eLoran 시험 송신국에서 9^th 펄스 변조방법과 Eurofix 변조방법으로 동시에 LDC 메시지를 송출할 수 있도록 설정하고, 인천과 평택의 eLoran 보정기준국의 데이터베이스 내 저장된 LDC 메시지를 분석해 변조방법에 따른 LDC 메시지 수신률을 분석한다. 또한 항로표지 관리선 인성 1호를 이용해 인천항 인근에서 실제 사용자의 LDC 메시지 수신률을 분석하였다. 본 연구결과는 eLoran 시범서비스 이후 본격적인 서비스 과정에서 중요하게 활용될 것으로 기대된다.

• Journal of Dental Anesthesia and Pain Medicine
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• v.20 no.1
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• pp.29-37
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• 2020

Background: This study evaluated the efficacy of three intraoral topical anesthetics in reducing the injection needle prick pain from local anesthetic among children aged 7-11 years old. Methods: It is a prospective, Interventional, parallel design, single-blind, randomized clinical trial in which subjects (n=90) aged 7-11 years were included in the study based on an inclusion criteria. Subjects were divided into three groups based on computer-generated randomization with an allocation ratio of 1:1:1. Groups A, B, and C received benzocaine 20% jelly (Mucopain gel, ICPA health products Ltd, Ankleshwar, India), cetacaine anesthetic liquid (Cetylite Industries, Inc, Pennsauken, NJ), and EMLA cream (2% AstraZeneca UK Ltd, Luton, UK), respectively, according to manufacturer's instructions, for 1 minute prior to local anesthetic injection. After application of topical anesthetic agent, for all the groups, baseline pre-operative (prior to topical anesthetic administration) and post-operative scores (after local anesthetic administration) of pulse rate was recorded using Pulse oximeter (Gibson, Fingertip Pulse Oximeter, MD300C29, Beijing Choice Electronic). Peri-operative (i.e., during the administration of local anesthesia) scores were recorded using Face, Legs, Activity, Cry, Consolability (FLACC) Scale, Modified Children hospital of Eastern Ontario Pain Scale (CPS) behavior rating scale, and Faces Pain Scale (FPS-R) - Revised (For self-reported pain). Direct self-reported and physiological measures were ascertained using FPS-R - Revised and Pulse oximeter, respectively, whereas CPS and FLACC scales assessed behavioral measures. To test the mean difference between the three groups, a one way ANOVA with post hoc tests was used. For statistical significance, a two-tailed probability value of P < 0.05 was considered as significant. Results: The Cetacaine group had significantly lower pain scores for self-report (P < 0.001), behavioral, and physiological measures (P < 0.001) than the other two groups. However, there was no significant difference between the Benzocaine group and EMLA group during palatal injection prick. Conclusion: Cetacaine can be considered as an effective topical anesthetic agent compared to benzocaine 20% jelly (Mucopain gel) and EMLA cream.

• Carbon letters
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• v.9 no.1
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• pp.17-22
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• 2008

A carbon nanotube (CNT) of diameter ~20 nm has been synthesized by spray pyrolysis of turpentine oil using Ni/Fe catalyst. Pellet of CNTs has been used as a target to produce semiconducting carbon thin film of band gap 1.4 eV. Presence of oxygen pressure in the pulse laser deposition (PLD) chamber helped to control the $sp^3/sp^2$ ratio to achieve the desired band gap. Results are discussed with the help of Raman spectra, SEM TEM micrographs and optical measurements suggest that semiconducting carbon thin film deposited by PLD technique has retained its nanotubes structure except that its diameter has increased from 20 nm to 150 nm.

• Reproductive and Developmental Biology
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• v.30 no.1
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• pp.1-5
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• 2006

Artificial activation of oocytes is a prerequisite for the successful cloning by nuclear transfer. This study investigated the effect of the different combination of activation agents such as electric pulse (E), thimerosal (Thi) + dithiothreitol (DTT), 6-dimethylaminopurine (6-DMAP) or cycloheximide (CH) on the developmental ability of porcine embryos derived from parthenogenetic activation (PA). PA embryos activated with chemicals showed significantly higher developmental rate to the blastocyst stage compared to the embryos activated with E alone ($21.5{\sim}28.1%$ vs. 18.0%, respectively). Of chemicals, Thi + DTT supported higher development to the blastoryst stage (28.1%). There was no significant difference in 1 pronucleus (PN) formation rate $(59.9{\sim}64.7%)$, but 2PN formation rate was significantly higher in PA embryos with additional activation using chemicals $(7.2{\sim}9.7%)$. In conclusion, this study shows that chemical activation after electric pulse can increase the development of porcine PA embryos.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.1
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• pp.5-9
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• 2004

In this paper, pulsed discharge is used to control the luminous color in gas discharge tubes. The luminous color of the positive column in gas discharge tubes filled with Hg-Ar-Ne (1: 9, 60［Torr］) and having no phosphor material, varies from red to blue emitted by the Ne and Hg from the pulsed discharge. With changing of pulse-width and frequency, the electron temperature in the transient period affects changes to the residual ion and metastable atom densities. The first metastable atoms containing energy levels of about 16.6 ［eV］have a very high probability that a collision will result in the ionization potential of Ar being 15.8 [eV]. The change of locus in the CIE chromaticity diagram with increasing pulse-width and frequency approves the variation of luminous color.