• Clinical and Experimental Pediatrics
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• 제61권10호
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• pp.315-321
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• 2018

Purpose: To investigate the effectiveness of transient intubation for surfactant administration and extubated to nasal continuous positive pressure (INSURE) for treatment of respiratory distress syndrome (RDS) and to identify the factors associated with INSURE failure in extremely premature infants. Methods: Eighty-four infants with gestational age less than 28 weeks treated with surfactant administration for RDS for 8 years were included. Perinatal and neonatal characteristics were retrospectively reviewed, and major pulmonary outcomes such as duration of mechanical ventilation (MV) and bronchopulmonary dysplasia (BPD) plus death at 36-week postmenstrual age (PMA) were compared between INSURE (n=48) and prolonged MV groups (n=36). The factors associated with INSURE failure were determined. Results: Duration of MV and the occurrence of BPD at 36-week PMA were significantly lower in INSURE group than in prolonged MV group (P<0.05), but BPD plus death at 36-week PMA was not significantly different between the 2 groups. In a multivariate analysis, a reduced duration of MV was only significantly associated with INSURE (P=0.001). During the study period, duration of MV significantly decreased over time with an increasing rate of INSURE application (P<0.05), and BPD plus death at 36-week PMA also tended to decrease over time. A low arterial-alveolar oxygen tension ratio (a/APO2 ratio) was a significant predictor for INSURE failure (P=0.001). Conclusion: INSURE was the noninvasive ventilation strategy in the treatment of RDS to reduce MV duration in extremely premature infants with gestational age less than 28 weeks.

• 대한토목학회논문집
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• 제12권1호
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• pp.207-217
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• 1992

본 연구에서는 기체 액체 고체의 직접접촉이 일어나는 3상 유동층 반응기를 이용하여 유입상승 유속에 의한 공극률의 변화와 생물막의 두께 및 밀도를 관측하였다. COD의 용적부하율은 반송비(r=0.2, 0.4, 0.6)로 조절하여 $201.12-1150.8g/m^3{\cdot}d$로 하였으며, 고체 매질로는 연탄재입자(평균유효입경 : 1.34 mm)와 유리비드(3 mm)를 사용하여, 매질의 차이에 따른 반응기의 효율에 대하여 비교하였다. 그 결과 반송비를 일정하게 고정시킨 경우, 연탄재 매질에 의한 생물막의 두께가 유리비드를 사용한 것보다 약 4.8배 두꺼우며, COD 제거 효율은 두 매질사이에는 변화가 거의 없으나, 암모니아성 질소의 제거에는 연탄재의 경우가 약간 높았다. 반응조내의 식종균으로는 합성폐수와 유사한 배지에서 동정 분리하여낸 토양미생물을 이용하였다 이 토양미생물은 기존의 활성슬러지균 보다 점착력과 침강성이 뛰어났다.

• 한국진공학회지
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• 제7권3호
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• pp.167-272
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• 1998

ECR plasma CVD를 이용한 SiOF박막은 낮은 유전상수를 가지고 있으며, 기존의 공정과의 정합성이 우수해 다층배선 공정에 채용이 유망한 재료이지만 수분의 흡수로 인한 유전율의 상승과 후속공정의 안정성이 문제점으로 부각되고 있다. 따라서 본 연구에서는 SiOF박막의 내흡습성과 후속공정에서의 안정성을 향상시키기 위하여 SiOF박막을 증착한 후 후속 산소 플라즈마 처리를 행하였다. SiOF박막은 산소 플라즈마 처리를 수행함으로써 SiOF박막의 밀도가 증가하고, 수분과의 친화력이 강한 Si-F 결합이 감소하는 것이 주요한 원인으로 사료된다. 하지만 플라즈마 처리 시간이 5분 이상으로 증가하면 유전율의 증가가 일어난다. 따라서 본 실험에서는 산소 플라즈마 처리조건이 마이크로파 전력이 700W, 공정 압력이 3mTorr, 기판온도가 $300^{\circ}C$일 경우 플라즈마 처리시간은 3분이 적당한 것으로 생각 된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.311-311
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• 2013

The resistance switching memory devices have several advantages to take breakthrough for the limitation of operation speed, retention, and device scale. Especially, the metal-oxide materials such as ZnO are able to fabricate on the flexible and visible transparent plastic substrate. Also, the quantum dots (QDs) embedded in dielectric layer could be improve the ratio between the low and the high resistance becauseof their Coulomb blockade, carrier trap and induced filament path formation. In this study, we irradiated 0.2-MeV-electron beam on the ZnO/QDs/ZnO structure to control the defect and oxygen vacancy of ZnO layer. The metal-oxide QDs embedded in ZnO layer on Pt/glass substrate were fabricated for a memory device and evaluated electrical properties after 0.2-MeV-electron beam irradiations. To formation bottom electrode, the Pt layer (200 nm) was deposited on the glass substrate by direct current sputter. The ZnO layer (100 nm) was deposited by ultra-high vacuum radio frequency sputter at base pressure $1{\times}10^{-10}$ Torr. And then, the metal-oxide QDs on the ZnO layer were created by thermal annealing. Finally, the ZnO layer (100 nm) also was deposited by ultra-high vacuum sputter. Before the formation top electrode, 0.2 MeV liner accelerated electron beams with flux of $1{\times}10^{13}$ and $10^{14}$ electrons/$cm^2$ were irradiated. We will discuss the electrical properties and the physical relationships among the irradiation condition, the dislocation density and mechanism of resistive switching in the hybrid memory device.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.913-916
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• 2001

From 1994 the cooperation between NEU of China and MJU of South Korea for study of ReBaCuO (Re=Rare earth elements) superconductors has been carried out. The progress has been got in following projects. Critical current density ($J_c$) of YBaCuO superconductor prepared by Melting Textured Growth (MTG) was improved. In the preparation of textured YBaCuO, 20 wt.% of YBaCuO 211 phase was added, which would be climactic for the microcracks in the textured YBaCuO. The effects of the 211 phase and Ag content on the superconductivity were studied and discussed in detail. The improved $J_c$ value was reached to 8$\times$10^4 A/cm^2 (77K,0T). Single phase $YbBa_{2}Cu_{3}O_{x}$ superconductor was sintered by the traditional powder metallurgical method, and its reaction process was studied. In recent years, NdBaCuO superconductor is being performed. The behavior of $Nd_{4}Ba_{2}Cu_{2}O_{10}$(Nd422 phase) and the solid solubility, x in the superconductor $Nd_{1+x}Ba_{2-x}Cu_{3}O_{y}$ by the heat treatment in the low oxygen partial pressure (1%) or Ar at $950{\circ}C$ were investigated. The zone-melting process was used to make oriented NdBaCuO superconductor in order to increase the critical current density.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
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• pp.801-803
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• 1998

We investigated Pt and $RuO_2$ as a bottom electrode and PZT thin film for ferroelectric applications. XRD examination shows that a mixed phase of (111) and (200) Pt peak for the temperature ranged from RT to $200^{\circ}C$, and a preferred (111) orientation for the substrate temperature of $300^{\circ}C$. From the XRD and AFM results, we recommend the substrate temperature of $300^{\circ}C$, 80 W for the Pt bottom electrode growth. From the study of an oxygen partial pressure from 0 to 50%, we learned that only Ru metal was grown with $0{\sim}5%$, a mixed phase of Ru and $RuO_2$ for $10{\sim}40%$, pure $RuO_2$ at 50%. Having optimized the bottom electrode growth conditions, we employed two step process in PZT film capacitor: PZT film growth at the low substrate temperature of $300^{\circ}C$ and then post RTA anneal treatments. PZT films were randomly oriented on $RuO_2$ and (110) preferentially oriented on Pt electrode. Leakage current density of PZT film demonstrated two to three orders higher for $RuO_2$ bottom electrode. From C-V results we observed a dielectric constant of PZT film higher than 1200. This paper presents the optimized process conditions of the bottom electrodes and properties of PZT thin films on these electrodes.

• 한국세라믹학회지
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• 제44권12호
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• pp.696-702
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• 2007

The family of (Sr,Mg)-doped $LaGaO_3$ compounds, which exhibit high ionic conductivity at $600-800^{\circ}C$ over a wide range of oxygen partial pressure, appears to be promising as the electrolyte for intermediate temperature solid oxide fuel cells. Conventional synthesis routes of (Sr,Mg)-doped $LaGaO_3$ compounds based on solid state reaction have some problems such as the formation of impurity phases, long sintering time and Ga loss during high temperature sintering. Phase stability problem especially, the formation of additional phases at the grain boundary is detrimental to the electrical properties of the electrolyte. From this point of view, we focused to synthesize single phase (Sr,Mg)-doped $LaGaO_3$ electrolyte at the stage of powder synthesis and to apply relatively low heat-treatment temperature using novel synthesis route based on combustion method. The synthesized powder and sintered bulk electrolytes were characterized by XRD, TG-DTA, FT-IR and SEM. AC impedance spectroscopy was used to characterize the electrical transport properties of the electrolyte with the consideration of the contribution of the bulk lattice and grain boundary to the total conductivity. Finally, relationship between synthesis condition and electrical properties of the (Sr, Mg)-doped $LaGaO_3$ electrolytes was discussed with the consideration of phase analysis results.

• Preventive Nutrition and Food Science
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• 제6권1호
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• pp.43-50
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• 2001

The effects of cardiac ischemia-reperfusion and $\beta$-adrenergic stimulation on metabolic function and energetics were investigated in Lan gendorff-perfused spontaneously hypertensive rat (SHR) hearts. Sarcoplasmic reticulum {TEX}$Ca^{2+}${/TEX}-dependent ATPase and cardiac lactate dehydrogenase (LDH) are additionally studied. The perfusion medium (1.0 mM {TEX}$Ca^{2+}${/TEX}) contained 5 mM glucose(+5 U/L insulin) and 2 mM pyruvate as substrates. Global ischemia was induced by reducing perfusion pressure of 100 to 40 cm {TEX}$H_{2}${/TEX}O, followed by 20 min reperfusin. Isoproterenol (ISO, 1$\mu$M) was infused for 10 min. Coronary vascular resistance and myocardial oxygen consumption ({TEX}$MVO_{2}${/TEX}) of SHR were increased in parallel with enhanced venous lactate during ischemia and reperfusion compared to those of Sprague Dawley (SD) hearts. Although ischemia-induced increase in venous lactate and combined adenosine plus inosine was abolished, coronary vasodilation produced in SD during reperfusion. In SHR, depressed reactive hyperemia was associated with a fall in cardiac ATP and CrP/Pi ratio and a rise in intracellular lactate/Pyruvate ratio. On the other hand, ISO produced coronary functional hyperemia and an increase in {TEX}$MVO_{2}${/TEX}. However, these responses were less than those in SHR hearts. The ATPase activity of SHR was attenuated in free {TEX}$Ca^{2+}${/TEX} concentrations used under basal condition and with ISO compared to that of SD. Venous lactate output and cardiac LDH activity were augmented in SHR as influenced by ISO. These results demonstrate that coronary reactive and functional hyperemia was dpressed in SHR, which cold be explained by alterations in the cytosolic phosphorylation potential and the cytosolic redox state manipulated by LDH, and by abnormal free calcium handling.

• 공업화학
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• 제31권3호
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• pp.317-322
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• 2020

수산화암모늄나이트레이트(HAN; NH₃OHNO₃)는 낮은 용융점과 증기압의 특성을 가지고 있고, 상대적으로 높은 산소균형을 이루고 있는 이온성 화합물이다. 본 연구에서는 높은 함량의 액상추진제를 제조하기 위한 산화제로 활용하기 위하여 이중용매를 적용하여 고체입자상으로 얻었다. 감압 하에서 액상의 HAN으로부터 수분을 증발시킨 후, 반용매로서 아세톤과 에탄올을 적용하여 추출한 입자상의 HAN에는 13.8 wt%의 수분이 포함되어 있었다. 아세톤을 단독으로 적용하였을 때, 합성수율은 질량기준으로 최대 88%이었고, TGA로 측정된 최대 함량은 86.2%, 분해온도는 160~205℃ 범위로 나타났다.

• 한국결정학회:학술대회논문집
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• 한국결정학회 2002년도 정기총회 및 추계학술연구발표회
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• pp.19-19
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• 2002

Perovskite-type titanate dielectrics have attracted much attention in memory devices such as DRAMs or FeRAMs due to their high dielectric constants. However, low volatility of the Ba, Sr, Pb or Zr precursors with only thd ligands has limitations in obtaining high quality thin films by liquid source metal organic chemical vapor deposition (LS-MOCVD) processes. To improve the volatility of these precursors, many attempts have been made such as adding polyether ligands to satisfy the coordinative saturation. We report the synthesis of new precursors Ba(thd)₂(tmeea) and Sr(thd)₂(tmeea), where tmeea = tris[2-(2-methoxyethoxy)ethyl]amino, and LS-MOCVD of barium strontium titanate (BSTO) thin films using these precursors. Due to increased basicity of amines compared with ethers, it is expected that the nitrogen-donor ligand will make a strong bond to a metal than an analogous oxygen-donor ligand, consequently improving the volatility and thermal behavior of these precursors. Thin films of BSTO were grown on Pt(111)/SiO₂/Si(100) substrates by LS-MOCVD using a cocktail source consisting of the conventional Ti precursor Ti(thd)₂(O/sup i/Pr), and these new Ba and Sr precursors. As-grown films were characterized by XPS, SEM, XRD, XRF, and C-V and I-V measurements. BSTO films grown at 420℃ were stoichiometric barium strontium titanate with very smooth surface morphology and their dielectric constants were found to be as targe as 450. Dependence of the composition, microstructure and the electrical properties of the BSTO films on the growth temperature, annealing temperature, working pressure, and the composition of the cocktail source will be discussed.