• Journal of Periodontal and Implant Science
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• v.32 no.4
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• pp.697-709
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• 2002

The present study was performed to evaluate the effect of citric acid on the change of implant surface microstructure according to application time. Implants with pure titanium machined surface, titanium plasma-sprayed surface, and sand-blasted, large grit, acid etched surface were utilized. Implant surface was rubbed with pH 1 citric acid for $\frac{1}{2}$ min., 1 min., 1 $\frac{1}{2}$ min., 2 min., and 3min, respeaively in the test group and implant surface was not treated in the control group. Then, the specimens were processed for scanning electron microscopic observation. The following results were obtained. 1. Both test and control group showed a few shallow grooves and ridges in pure titanium machined surface implants. There were not significant differences between two groups. 2. In titanium plasma-sprayed surfaces, round or amorphous particles were deposited irregularly. The irregularity of titanium plasma-sprayed surfaces conditioned with pH 1 citric acid was lessened and the cracks were increased relative to the application time of pH 1 citric acid. 3. Sand-blasted, large grit, acid etched surfaces showed the macro/micro double roughness. The application of pH 1 citric acid didn't change the characteristics of the sand-blasted, large grit, acid etched surfaces. In conclusion, the application of pH 1 citric acid to titanium plasma-sprayed surface is improper. And pure titanium machined surface implants and sand-blasted, large grit, acid etched surface implants can he treated with pH 1 citric acid for peri-implantitis treatment if the detoxification of these surfaces could be evaluated.

• Resources Recycling
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• v.26 no.6
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• pp.3-9
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• 2017

In this study, plasma arc remelting behaviors according to arc current, arc voltage, and types of plasma gas were investigated using Kroll processed Ti sponges as anode. In the discharge pressure range of vacuum pump ($200{\sim}300kgf/cm^2$), the arc voltage did not vary greatly with the increase of discharge pressure at a given arc length. This means that the pressure in the vacuum chamber during operation hardly changes and the atmospheric pressure maintains. Under various conditions of arc currents (700~900A), the arc voltage slightly increased with arc current. The effects of anode materials and operational variables on the arc length-arc voltage relationship were compared with the results in previous studies. When the atmospheric gas changed from argon to helium, double effect of improvement on the output of the steady state was observed. The increase of output in the plasma arc device was accompanied by an increase in the melting rate of the Ti sponge and the quality of the ingot surface was also improved. The plasma arc remelting of the new scrap titanium and the old scrap zirconium alloy could result in the fabrication of an ingot with high surface quality.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.3
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• pp.403-408
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• 2008

The gyroscope is the sensor for detecting the rotation in inertial reference frame and constitute the navigation system together an accelerometer. As the inertial reference equipment for attitude determination and control in the satellite, the mechanical gyroscope has been used but it bring the disturbance for mass unbalance so the disturbance give a bad influence to the observation satellite mission because the mechanical gyroscope has the rotation parts. During the launch. The mechanical gyroscope is weak in vibration, shock and has the defect of narrow operating temperature range so it need the special design in integration. Recently the low orbit observation satellite for seeking the high pointing accuracy of image camera payload accept the FOG(Fiber Optic Gyro) or RLG(Ring Laser Gyro) for the attitude determination and control. The Ring Laser Gyro makes use of the Sanac effect within a resonant ring cavity of a He-Ne laser and has more accuracy than the other gyros. It need the 1000V DC to create the He-Ne plasma in discharge tube. In this paper, the design process of the High Voltage Power Supply for RLG(Ring Laser Gyroscope) is described. The specification for High Voltage Power Supply (HVPS) is proposed. Also, The analysis of flyback converter topology is explained. The Design for the HVPS is composed of the inverter circuit, feedback control circuit, high frequency switching transformer design and voltage doubler circuit.

• Journal of The Korean Astronomical Society
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• v.47 no.4
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• pp.147-152
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• 2014

We present measurements of the Fe $K{\alpha}$ emission line of the intermediate polar V1223 Sagittarii observed with the Suzaku satellite. The spectrum is modeled with an absorbed thermal bremsstrahlung spectrum and three Gaussians for the three components of the Fe $K{\alpha}$ lines. We resolve the neutral or low-ionized (6.41keV), He-like (6.70keV), and H-like (7.00keV) iron lines. We also obtain a thermal continuum temperature of 25 keV, which supports a thermal origin of the hard X-rays observed from the shock heated layers of gas between the white dwarf and the shock front. Hence, we believe that the He-like and H-like lines are from the collisional plasma. On the origin of the Fe $K{\alpha}$ fluorescence line, we find that it could be partly from reflections of hard X-rays from the white dwarf surface and the $N_H$ absorption columns. We also discuss the Fe $K{\alpha}$ emission line as veritable tool for the probe of some astrophysical sites.

• Clinical and Experimental Pediatrics
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• v.58 no.12
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• pp.505-508
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• 2015

It is uncommon for pediatric patients with rhabdomyosarcoma to present with clinical and/or laboratory features of disseminated intravascular coagulation (DIC). We report a case of metastatic alveolar rhabdomyosarcoma with severe bleeding because of DIC in a 13-year-old boy. He experienced persistent oozing at the site of a previous operation, gross hematuria, and massive epistaxis. Two weeks after initiating combination chemotherapy consisting of vincristine, doxorubicin, and cyclophosphamide, the patients' laboratory indications of DIC began to resolve. During this period, the patient received massive blood transfusion of a total of 311 units (26 units of red blood cells, 26 units of fresh frozen plasma, 74 units of platelet concentrates, 17 units of single donor platelets, and 168 units of cryoprecipitate), antithrombin-III and a synthetic protease inhibitor. Despite chemotherapy and radiation therapy, he died 1 year later because of disease progression. In children with metastatic rhabdomyosarcoma and massive DIC, prompt chemotherapy and aggressive supportive care is important to decrease malignancy-triggered procoagulant activities.

• Journal of Veterinary Clinics
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• v.34 no.6
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• pp.437-440
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• 2017

A five-month-old, male Domestic Korean shorthair was referred to our hospital with a history of lethargy, anorexia, and globoid cardiac silhouette on thoracic radiography. Physical examination showed dehydration and anemia was revealed on blood analysis. On thoracic radiography and echocardiography, the patient showed pericardial effusion and ultrasound-guided pericardiocentesis was performed. A Rivalta test of the pericardial effusion showed a positive result. As the patient had recurrent pericardial effusion, pericardiectomy was performed. He was tentatively diagnosed with wet form feline infectious peritonitis (FIP) and treated with Polyprenyl immunostimulant (PI). Neurological signs were eventually seen and he was euthanized. Histopathologic changes with markedly expanded neutrophils, lymphocytes, plasma cells, and macrophages with fibrous connective tissue and collagenous fibers were detected. Immunohistochemistry for FIP antigen was performed and results showed FIPV-positive multifocal aggregates of cells. Pericardial effusion is an atypical condition in cats with FIP, but can be presented. This case report describes FIP with pericardial effusion in a cat, in which definitive diagnosis of FIP was done using biopsy via pericardiectomy.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1488-1490
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• 2008

The gyroscope is the sensor for detecting the rotation in inertial reference frame and constitute the navigation system together an accelerometer. As the inertial reference equipment for attitude determination and control in the satellite, the mechanical gyroscope has been used but it bring the disturbance for mass unbalance so the disturbance give a bad influence to the observation satellite mission because the mechanical gyroscope has the rotation parts. During the launch, The mechanical gyroscope is weak in vibration, shock and has the defect of narrow operating temperature range so it need the special design in integration. Recently the low orbit observation satellite for seeking the high pointing accuracy of image camera payload accept the FOG(Fiber Optic Gyro) or RLG(Ring Laser Gyro) for the attitude determination and control. The Ring Laser Gyro makes use of the Sanac effect within a resonant ring cavity of a He-Ne laser and has more accuracy than the other gyros. It need the 1000V DC to create the He-Ne plasma in discharge tube. In this paper, the design process of the High Voltage Power Supply for RLG(Ring Laser Gyroscope) is described. The specification for High Voltage Power Supply(HVPS) is proposed. Also, The analysis of flyback converter topology is explained. The Design for the HVPS is composed of the inverter circuit, feedback control circuit, high frequency switching transformer design and voltage doubler circuit.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.223.2-223.2
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• 2013

비정질 실리콘은 태양전지, 트랜지스터, 이미지 센서 등 다양한 분야에서 응용되고 있으며 새로운 박막 소자 개발을 위한 소재로서 많은 연구가 진행되고 있다. 하지만 소자개발에 있어 공정상에서 발생하는 비정질 실리콘 박막의 높은 응력(stress)은 소자의 특성을 떨어뜨리는 문제점을 갖는다. 따라서 우수한 특성의 소자 개발을 위해서는 보다 낮은 응력을 갖는 비정질 실리콘 박막 증착 및 공정 조건에 따른 응력 조절이 필요하다. 저응력의 비정질 실리콘 박막 증착은 보다 낮은 반응온도에서 증착속도를 최소로 하여 성장되어야 하는데 이는 플라즈마기상증착(Plasma enhanced chemical vapor deposition, PECVD) 시스템에 의해 가능하다. 따라서 본 연구에서는 PECVD 시스템을 사용하여 비정질 실리콘 박막을 증착하였고 그 특성을 분석하였다. 이 때 증착 온도, rf 파워, 공정 압력은 실험결과로부터 얻어진 낮은 박막 증착속도 하에서 안정적으로 증착이 가능한 조건으로 일정하게 유지하여 실험하였다. 공정 가스는 SiH4/He/N2의 혼합가스를 사용하였고 응력 조절을 위해 SiH4/He 가스비를 일정한 비율로 변화하여 비정질 실리콘 박막을 증착하였다. 증착된 박막의 두께 및 표면 특성은 field emission scanning electron microscopy 및 atomic force microscopy를 이용하여 분석하였고, energy dispersive X-ray 분석을 통하여 정량 및 정성적 분석을 수행하였다. 그리고 stress measurement system을 이용하여 박막의 응력을 측정하였고 X-ray diffraction 측정 및 ellipsometry 측정으로부터 증착된 박막의 결정성, 굴절률 및 oiptical bandgap을 분석하였다.

• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1490-1500
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• 2024

Helium-induced defect nucleation and accumulation in polycrystalline W and W0.5 wt%ZrC (W0.5ZrC) were studied in-situ using the transmission electron microscopy (TEM) combined with 40 keV He⁺ irradiation at 800 and 1000℃ at the maximum damage level of 1 dpa. Radiation-induced dislocation loops were not observed in the current study. W0.5ZrC was found to be less susceptible to irradiation damage in terms of helium bubble formation and growth, especially at lower temperature (800 ℃) when vacancies were less mobile. The ZrC particles present in the W matrix pin the forming helium bubbles via interaction between C atom and neighbouring W atom at vacancies. This reduces the capability of helium to trap a vacancy which is required to form the bubble core and, as a consequence, delays, the bubble nucleation. At 1000 ℃, significant bubble growth occurred in both materials and all the present bubbles transitioned from spherical to faceted shape, whereas at 800 ℃, the faceted helium bubble population was dominated in W.

• Journal of The Korean Society of Clinical Toxicology
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• v.12 no.2
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• pp.92-96
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• 2014

Dabigatran is the first oral direct thrombin inhibitor approved by the US Food and Drug Administration (FDA) for prevention of stroke and systemic embolism in patients with nonvalvular atrial fibrillation. Because dabigatran is excreted mainly by the kidneys, serum levels of dabigatran can be elevated to a supratherapeutic range in patients with renal failure, predisposing to emergent bleeding. We describe the case of a 66-year-old man taking dabigatran 150 mg twice daily for atrial fibrillation and cerebral infarction who presented with hematochezia and disseminated intravascular coagulation. Laboratory evaluation showed a hemoglobin level of 6.3 g/dL, platelets of $138,000/mm^3$, activated partial thromboplastin time (aPTT) of 10 s, and an international normalized ratio (INR) of 8.17. Colonoscopy showed a bleeding anal fissure. Hemostasis was provided by hemoclips and packed red blood cells and fresh frozen plasma were transfused. Since then, there was no further hematochezia, however, bleeding including oral mucosal bleeding, hematuria, and intravenous site bleeding persisted. At presentation, his serum creatinine was 4.96 mg/dL (baseline creatinine, 0.9 mg/dL). Dabigatran toxicity secondary to acute kidney injury was presumed. Because acute kidney injury of unknown cause was progressing after admission, he was treated with hemodialysis. Fresh frozen plasma transfusion was provided with hemodialysis. At 15 days from admission, there was no further bleeding, and laboratory values, including hemoglobin, partial thromboplastin time, and prothrombin time were normalized. He was discharged without bleeding. After 2 months, he undergoes dialysis three times per week and no recurrence of bleeding has been observed.