• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.182-182
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• 2010

본 연구에서는 Pt 배면전극에 다양한 조건에서의 ZnO를 성장하여 Schottky 구조를 제작, 접합 특성 및 자외선 검출 특성을 연구하였다. $Al_2O_3$ 기판에 Mirror-like하며 고결정성을 갖는 Pt(111) 배면전극을 형성 후, ZnO 박막의 성장 조건에 따른 접합 특성을 확인하기 위하여 기판온도와 산소분압을 각각 $400{\sim}600^{\circ}C$ ($50^{\circ}C$ 단계), 0~60 sccm (15 sccm 단계)로 성장하였다. 이에 따른 구조적 특성변화를 확인하기 위하여 주사전자현미경 및 X선 회절 특성을 분석하였으며, 전류-전압 특성 곡선을 분석을 통하여 최적의 Schottky contact 형성을 위한 ZnO 성장조건을 규명하고자 하였다. $H_2O_2$를 이용한 표면처리와 Rapid Thermal Annealing (RTA)를 이용한 열처리 과정을 통하여 표면 처리 전 후의 전기적 특성과 광학적 특성의 변화를 비교 분석하였다. 또한 Ohmic 접촉으로 상부전극을 형성, ZnO Schottky photodiode 구조를 제작하여 UV-A, B, C 영역에 따른 UV반응 특성을 분석하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.287-287
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• 2010

휴대용 기기의 사용이 증가하면서 배터리의 고용량화와 소형화가 요구되고 있다. 특히 내시경 캡슐과 같은 의료용 센서 기기에서는 소형화가 매우 중요하며 인체에 해로운 액체전해질이 들어가지 않는 것이 바람직하다. 최근 무선센서, RFID 태그, 스마트 카드 등을 위하여 고체전해질을 사용하는 박막 마이크로 배터리가 개발되고 있으나, 에너지 저장용량이 작아 응용분야가 제한적이다. Si wafer 위에 형성된 고단차의 3차원 구조 위에 박막 배터리를 형성한다면 표면적 증가에 의해 에너지 저장용량 역시 크게 증가할 것이며, Si 기반의 반도체, 디스플레이, 태양전지 등과 쉽게 집적이 가능할 것이다. 본 연구에서는 펄스 레이저 증착법(Pulsed Laser Deposition)으로 리튬 배터리의 cathode 물질인 $LiCoO_2$를 박막으로 제조하고 그 특성을 연구하였다. 펄스 레이저 증착법은 저온 증착이 가능하고 타겟 물질과 같은 조성의 박막을 증착하는 것이 용이한 장점이 있다. Pt, TiN 등의 기판 위에 $LiCoO_2$ 박막을 증착하고 증착 온도와 산소($O_2$) 분압이 박막의 조성, 미세구조, 결정성, 그리고 전하저장용량에 미치는 영향을 고찰하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.04a
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• pp.65-66
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• 2007

비대칭 마그네트론을 이용하여 사원계 CrTiAlN 나노 복합 박막을 합성하였고 합성된 박막의 특성을 분석하였다. CrTiAlN 나노복합 박막의 미세구조는 CrN (111)과 CrN (200)방향으로 성장하였고 기계적 특성은 $30\;{\sim}\;39\;GPa$의 경도 값을 얻었다. 질소 분압이 0.33 Pa에서 가장 높은 경도 값을 얻을 수 있었다.

• Journal of the Semiconductor & Display Technology
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• v.20 no.2
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• pp.82-86
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• 2021

In this study, we investigated the oxygen partial pressure effect of ITO films for electrodes of oxide-based Thin-Film Transistor (TFT). Firstly, we deposited single ITO films on the glass substrate at room temperature. ITO films were prepared at the various partial pressures of oxygen gas 0-7.4% (O₂/(Ar+O₂)). As increasing oxygen on the process of film deposition, electrical properties were improved and optical transmittance increased in the visible light range (300-800 nm). For the electrode of TFT, we fabricated a TFT device (W/L=1000/200 ㎛) with ITO films as the source and drain electrode on the silicon wafer. Except for the TFT device combined with ITO film prepared at the oxygen partial pressure ratio of 7.4%, We confirmed that TFT devices with ITO films via FTS system operated as a driving device at threshold voltage (V_th) of 4V.

• Tuberculosis and Respiratory Diseases
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• v.44 no.1
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• pp.136-145
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• 1997

Background : Tracheal Gas Insufflation (TGI) is one of the newer ancillary measures in mechanical ventilation employed to enhance carbon dioxide elimination. TGI exerts its effect through reduction of deadspace ventilation, but the factors determining its effect are not well studied yet. Method : The subjects were seven mechanically-ventilated patients ($58.8{\pm}10.6$ yrs) who showed increased physiologic deadspace greater than 60%. After 30 nun of stabilization with 100% oxygen on pressure control ventilation, continuous flow TGI was administered via the insufflation lumen of Hi-Lo Jet Tracheal Tube (Mallincrodt, USA) for 15 min at 3 L/min and 5 L/min each. Results : $PaCO_2$ was decreased ($51.4{\pm}17.6$ at baseline, $49.1{\pm}18.9$ at TGJ 3 L/min $45.0{\pm}14.9$ mm Hg at TGI 5 L/min, p=0.050), and pH was increased ($7.37{\pm}0.12$, $7.38{\pm}0.13$, $7.39{\pm}0.12$, respectively, p=0.037) while mixed expired $CO_2$ ($P_ECO_2$) was not changed significantly from baseline (p=0.336) by TGI. Physiologic deadspace(Vdphy) was decreased ($73.0{\pm}7.9$% at baseline, $69.8{\pm}10.0$% at TGI 3 L/min, and $67.1{\pm}10.1$% at TGI 5 L/min, p=0.015). $AaDO_2$(p=0.147), Vt(p=0.2140), Pmean(p=0.7788) and mean arterial pressure(p=0.4169) were not changed. The correlation between % maximal decrease of Vdphy were r=0.790 with the ratio of baseline Vdana/Vdphy(p=0.035) and r=-0.754 with baseline Vdalv(p=0.050). Conclusion: TGI was effective in reducing $PaCO_2$ and deadspace, and the deadspace-reducing effect was best correlated with baseline anatomic/physiologic deadspace ratio.

• Tuberculosis and Respiratory Diseases
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• v.42 no.3
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• pp.361-369
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• 1995

Background: A number of different weaning techniques can be employed such as spontaneous breathing trial, Intermittent mandatory ventilation(IMV) or Pressure support ventilation(PSV). However, the conclusive data indicating the superiority of one technique over another have not been published. Usually, a conventional spontaneous breathing trial is undertaken by supplying humidified $O_2$ through T-shaped adaptor connected to endotracheal tube or tracheostomy tube. In Korea, T-tube trial is not popular because the high-flow oxygen system is not always available. Also, the timing of extubation is not conclusive and depends on clinical experiences. It is known that to withdraw the endotracheal tube after weaning is far better than to go through any period. The tube produces varying degrees of resistance depending on its internal diameter and the flow rates encountered. The purpose of present study is to evaluate the effectiveness of weaning and extubation following a 60 minutes spontaneous breathing trial with simple oxygen supply through the endotracheal tube. Methods: We analyzed the result of weaning and extubation following a 60 minutes spontaneous breathing trial with simple oxygen supply through the endotracheal tube in 18 subjects from June, 1993 to June, 1994. They consisted of 9 males and 9 females. The duration of mechanical ventilation was from 38 hours to 341 hours(mean: $105.9{\pm}83.4$ hours). In all cases, the cause of ventilator dependency should be identified and precipitating factors should be corrected. The weaning trial was done when the patient became alert and arterial $O_2$ tension was adequate($PaO_2$ > 55mmHg) with an inspired oxygen fraction of 40%. We conducted a careful physical examination when the patient was breathing spontaneously through the endotracheal tube. Failure of weaning trial was signaled by cyanosis, sweating, paradoxical respiration, intercostal recession. Weaning failure was defined as the need for mechanical ventilation within 48 hours. Results: In 19 weaning trials of 18 patients, successful weaning and extubation was possible in 16/19(84.2 %). During the trial of spontaneous breathing for 60 minutes through the endotracheal tube, the patients who could wean developed slight increase in respiratory rates but significant changes of arterial blood gas values were not noted. But, the patients who failed weaning trial showed the marked increase in respiratory rates without significant changes of arterial blood gas values. Conclusion: The result of present study indicates that weaning from mechanical ventilation following a 60 minutes spontaneous breathing with $O_2$ supply through the endotracheal tube is a simple and effective method. Extubation can be done at the same time of successful weaning except for endobronchial toilet or airway protection.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.1
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• pp.1-8
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• 2015

To evaluate accuracy and precision of determination of total alkalinity ($Alk_T$) and carbon dioxide ($TCO_2$) derived from present study, experiment was applied with $CO_2$ CRM (Batch 132, Scripps Institution of Oceanography; $Alk_T=2229.24{\pm}0.39{\mu}mol/kg$, $TCO_2=2032.65{\pm}0.45{\mu}mol/kg$). As the result, average concentration of $Alk_T$ and $TCO_2$ was $2354.09{\mu}mol/kg$ (~5.6% difference with $CO_2$ CRM) and $2089.60{\mu}mol/kg$ (~2.3% difference with $CO_2$ CRM), respectively. For previous method (Gran Titration) by addition $NaHCO_3$ to deionized water($Alk_T$ $2023.33{\mu}mol/kg$), average concentration was $2193.39{\mu}mol/kg$ (sd=57.15, n=7). Whereas, average concentration was $2017.02{\mu}mol/kg$ (sd=10.98, n=7) for the present study. Recovery yield experiments of total alkalinity in deionized water and seawater were implemented by addition of $NaHCO_3$. The recovery yield of deionized water in the range 0 to $4952.39{\mu}mol/kg$ was 100.8% ($R^2$=0.999), and seawater in the range 0 to $2041.32{\mu}mol/kg$ was 102.3% ($R^2$=0.999). Comparison of $pCO_2$ sensor (PSI $CO_2-Pro^{TM}$) with present method showed very meaningful correlation coefficient ($R^2$=0.977) in the range of 427 to $705{\mu}atm$ and 9.16 to $15.24{\mu}mol/kg$ throught elapsed time for two weeks. Field experiment of diurnal variation of total carbon dioxide was accomplished at Sachon harbor in the coastal waters of East Sea of Korea. Concentration of $Alk_T$ and $TCO_2$ was increased during night, and decreased during daylight hours. The results showed mirror type between $TCO_2$ and dissolved oxygen, which was attributable to photosynthesis and respiration of phytoplankton. Also, open ocean field study was performed to obtain vertical profile of $Alk_T$ and $TCO_2$ in C-C zone (Clarion-Clipperton Fracture Zone), Northeastern Pacific. Average concentrations of $Alk_T$ in the surface mixed layer (0~60 m) and deeper layer below 200 m were $2422.38{\mu}mol/kg$ (sd=78.73, n=20) and $2465.87{\mu}mol/kg$ (sd=57.68, n=103), respectively. And average concentrations of $TCO_2$ were $2134.47{\mu}mol/kg$ (sd=65.4, n=20) and $2431.87{\mu}mol/kg$ (sd=65.02, n=103) in the same depth ranges such as $Alk_T$. Vertical distributions of $Alk_T$ and $TCO_2$ concentrations tended to increase with depth, and analyzed concentrations showed slightly higher than those of previous studies in this area.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.4
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• pp.599-604
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• 1998

We have investigated Pt and $RuO_2$ as a bottom electrode for ferroelectric capacitor applications. The bottom electrodes were prepared by using an RF magnetron sputtering method. Some of the investigated parameters were a substrate temperature, gas flow rate, RF power for the film growth, and post annealing effect. The substrate temperature strongly influenced the surface morphology and resistivity of the bottom electrodes as well as the film crystallographic structure. XRD results on Pt films showed a mixed phase of (111) and (200) peak for the substrate temperature ranged from RT to $200^{\circ}C$, and a preferred (111) orientation for $300^{\circ}C$. From the XRD and AFM results, we recommend the substrate temperature of $300^{\circ}C$ and RF power 80W for the Pt bottom electrode growth. With the variation of an oxygen partial pressure from 0 to 50%, we learned that only Ru metal was grown with 0~5% of $O_2$ gas, mixed phase of Ru and $RuO_2$ for $O_ 2$ partial pressure between 10~40%, and a pure $RuO_2$ phase with $O_2$ partial pressure of 50%. This result indicates that a double layer of $RuO_2/Ru$ can be grown in a process with the modulation of gas flow rate. Double layer structure is expected to reduce the fatigue problem while keeping a low electrical resistivity. As post anneal temperature was increased from RT to $700^{\circ}C$, the resistivity of Pt and $RuO_2$ was decreased linearly. This paper presents the optimized process conditions of the bottom electrodes for memory device applications.

• Tuberculosis and Respiratory Diseases
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• v.48 no.2
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• pp.210-222
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• 2000

Background: Endothelin(ET) is the most potent vasoconstrictor and bronchoconstrictor. The plasma ET-1 level is elevated in patients with acute pulmonary thromboembolism(APTE). This finding suggest that ET-1 may be an important mediator in the cardiopulmonary derangement of APTE. But whether ET-1 is a pathogenic mediator or a simple marker of APTE is not known. The role of ET-1 in the pathogenesis of cardiopulmonary dysfunction in APTE(delete) was investigated through an evaluation of the effects of $ET_A$-receptor antagonist on APTE. The increase in local levels of preproET-1 mRNA and ET-1 peptide in the embolized lung was also demonstrated. Methods: In a canine autologous blood clot pulmonary embolism model, $ET_A$-receptor antagonist(10 mg/kg intravenously, n=6) was administered one hour after the onset of the embolism. Hemodynamic measurements, blood gas tensions and plasma levels of ET-1 immunoreactivity in this treatment group were compared with those in the control group(n=5). After the experiment., preproET-1 mRNA expression(using Northern blot analysis) and the distribution of ET-1(by immunohistochemical analysis) in the lung tissues were examined. Results: The increases in pulmonary arterial pressure and pulmonary vascular resistance of the treatment group were less than those of the control group. Decrease in cardiac output was also less in the treatment group. Complications such as systemic arterial hypotension and hypoxemia did not occur with the administration of $ET_A$-receptor antagonist The plasma level of ET-1 like(ED: what does 'like' mean?) immunoreactivity was increased after embolization in both groups but was significantly higher in the treatment group. The preproET-1 mRNA and ET-1 peptide expressions were increased in the embolized lung. Conclusion: ET-1 synthesis increases with embolization in the lung and may plays play an important role in the pathophysiology of cardiopulmonary derangement of APTE. Furthermore, $ET_A$-receptor antagonist attenuates cardiopulmonary alterations seen in APTE, suggesting a potential benefit of this therapy.

• Tuberculosis and Respiratory Diseases
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• v.43 no.4
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• pp.491-499
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• 1996

Background : Pleural effusion is a common disease in clinical practice but its effect on pulmonary function and altered pulmonary mechanics after removal of effusion are not still largely understood. Previous studies have shown that there is little or a relatively small improvement in pulmonary function and arterial blood oxygenation after therapeutic thoracentesis. The present study was designed to assess the effect on pulmonary function of pleural effusion and to test whether there was a significant improvement in pulmonary function and arterial oxygenation after thoracentesis and to observe long tenn effect after thoracentesis. Method : We examined flow-volume curve, body box and arterial blood gas analysis according to severity of effusion, present symptom, and symptom duration. Then, we measured changes of pulmonary function after thoracentesis and observed longterm effect after thoracentesis. Result: 1) Pleural effusion cause restrictive pulmonary insufficiency. Not only functional impairment of small airway but also large airway is provoked. 2) MMFR, FEV1, Raw, POz are earlier improved than FVC and TLC after thoracentesis and patients without complication have mild restrictive pulmonary insufficiency after longterm observation. 3) FVC, FEV1, & TLC are similarly restricted as severity of pleural effusion and po, is relatively decreased. 4) Cases with symptom duration 1 week or less and cases with dyspnea have more severe pulmonary insufficiency than others. 5) The flow volume curves show a relatively greater improvement in flow rates at large lung volumes than small airway. 6) Significant relationship is shown between first thoracentesis amount and changes of FEV1, FVC, TLC. Conclusion: Pleural effusion cause restrictive pulmonary insufficiency and not only functional impairment of small airway impairment but also large airway is provoked. Then, Pulmonary function is progressively improved after thoracentesis and remained mild restrictive pulmonary insufficiency after recovery.