• 한국초전도학회:학술대회논문집
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• v.9
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• pp.388-391
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• 1999

Well oriented Bi2212 superconductor thick films were formed successfully on a copper substrate by liquid reaction between a Cu-free precursor and Cu tape method in which Cu-free BSCO powder mixture was' printed on copper plate and heat-treated. And we examined the effect of heat-treatment atmosphere for the superconducting properties and microstructure of Bi2212. The composition of Cu-free BSCO powder mixture was Bi$_2O_3$ : SrCO$_3$ : CaCO$_3$ = 1.2~2 : 1 : 1 and the heat-treatment for the superconducting formation reaction was performed in air, oxygen, nitrogen and low oxygen pressure. At heat-treatment temperature, the printing layer partially melt by reacting with CuO of the oxidizing copper plate, and the nonsuperconducting phases present in the melt are typically Bi-free phases and Cu-free phases. Among the nonsuperconducting phases, it is known that the (Sr,Ca)CuO$_3$ phase restrain the formation of the Bi2212 superconducting phase. Because a kind of the nonsuperconducting phases is controled by the oxygen partial pressure, the optimum condition in which the remnants of the second phases don't leave in the fully processed conductor was determined by XRD and the critical tempera to re (Tc) analysis.

• Membrane Journal
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• v.9 no.1
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• pp.25-35
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• 1999

The sorption and permeation experiments with $O_2$ and $N_2$ were performed with poly sulfone hollow-fiber membrane to obtain oxygen-enriched air. Sorption of $O_2$ on poly sulfone membrane was 1.5'||'&'||'not;2.0 times higher than that of N2. Sorption of oxygen and nitrogen in poly sulfone membrane was described satisfactorily with "dual-mode sorption model". In the low pressure range below 3kgr!cm', about 85% of total sorption was Langmuir-type sorption and only 15% was Henry-type sorption. In the higher pressure above 3kgf/${cm}^2$, Langmuir sorption sites became almost saturated and reached asymptote, and the increase in total sorption with pressurizing might be due to the Henry~type sorption. The ideal separation factor ( P $O_2$/ P $N_2$) was in the range of 2~4, while the actual separation factor for the mixture was reduced to the value of 1.7~2.2.2.2.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.04a
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• pp.45-47
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• 2001

Due to pressure from threatened legislation in Europe, consumer and governmental pressure in Japan, and glob머 market considerations in the US, there is a rapidly growing interest in lead-free solderinger, Although the move to lead free soldering seems inevitable, many problems will arise in production assembly. It is generally acknowledged that the lead-free solders available offer a much s smaller process window than lead/tin, related mainly to the higher soldering temperatures which naturally result from increases of liquidus temperatures of at least 300 C. However, raising reflow temperatures from the current 220-2300 C to 250 2600 C will lead to problems with the boards and components as well as i increasing oxidation effects. There is a need to keep reflow temperatures low without reducing solderablity. Some results on benefits of inert atmospheres are discussed in this paper. For example, testing in a nitrogen atmosphere, with 300 ppm oxygen, by the N National Physical Laboratory (NPU has revealed clear benefits for ine$\pi$mg lead-free alloys, by restoring the solderability to lead/tin levels, by enabling lower soldering temperatures. However, there has been little testing over a range of oxygen levels in nitrogen and this is an important issue in determining n nitrogen supply and oven costs. Some results are reported here from work by NPL conducted for BOC in w which solderability was evaluated for tin기ead and tin/silver/copper eutectic a alloys in a wetting balance over a range of oxygen levels form 10 ppm to 21% ( (air). The studies confirm that acceptable wetting times occur in inert atmospheres a at soldering temperatures 20 to 300 C lower than are possible in air.

• Journal of the Korean Society of Physical Medicine
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• v.17 no.4
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• pp.37-43
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• 2022

PURPOSE: To find out how wearing a mask due to COVID-19 affects cardiovascular function as the pace of walking changes. METHODS: Forty-nine college students (27 men, 22 women) were subjected to treadmill exercises without masks (Group I) and wearing masks (Group II). The body temperature, heart rate, oxygen saturation, and blood pressure were measured to determine the changes in cardiovascular function. These parameters were measured at rest (Control I), low-intensity (Control II), medium-intensity (Control III), and high-intensity (Control IV) before and after exercise. RESULTS: Significant differences in heart rate were observed between Control III and Control IV, and a significant difference in oxygen saturation was noted in Control IV. Significant differences in the exercise intensity change in Group II were as follows: Body temperature was Control IV compared to Control I and Control II, heart rate was Control III and Control IV compared to Control I and Control II, and Control IV compared to Control III. The heart rate was Control III and Control IV compared to Control I and Control II, Control IV for Control III, oxygen saturation was Control IV compared to Control I, blood pressure was Control II and Control III and Control IV compared to Control I, and Control IV compared to Control II. CONCLUSION: Exercising when wearing a mask affects the cardiovascular system. Therapists should consider the patient's condition when setting the exercise intensity. In particular, therapists should be more careful when setting the exercise intensity of patients with cardiovascular disease.

• Journal of Sensor Science and Technology
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• v.10 no.4
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• pp.222-231
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• 2001

The material properties of $SnO_2$ were investigated as a function of the amount of $Fe_2O_3$, the partial pressure of oxygen, the concentration of CO gas, and temperature. $Fe_2O_3$-doped $SnO_2$ thick films were prepared by the screen printing technique on alumina substrate. The specimens sintered at $700^{\circ}C$ for 6 hours showed little difference of the grain size and narrow distribution with the content of $Fe_2O_3$. The electrical conductance of undoped $SnO_2$ is high at low firing temperature and at low partial pressure of oxygen. The electrical conductance of $Fe_2O_3-$-doped $SnO_2$ is increased with measurement temperature, but decreased with the content of $Fe_2O_3$. The dependence of oxygen partial pressure is decreased with dopant addition. The highest sensitivity and the good properties of response speed and repeatability for CO gas were observed on the specimen with 0.1 mol% $Fe_2O_3$ at $350^{\circ}C$.

• Journal of Chest Surgery
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• v.29 no.7
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• pp.723-727
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• 1996

An adequate exposure is important in thoracoscopic procedures. The insufflation of $CO_2$has been demonstrated to aid in compressing lung parenchyma, and act as a retractor when combined with changes in patient's position. However, a recent study demonstrated that $CO_2$insufflation during thoracoscopy in the pig has adverse hemodynamic consequences. We prospectively studied 12 patients undergoing thoracoscopy to evaluate the effect of $CO_2$insufflation in the clinical setting. The mean arterial pressure, heart rate, central venous pressure, arterial oxygen saturation, and end-tidal $CO_2$pressure were monitored. Measurements were determined at baseline, at the initiation of one-lung ventilation, and at intrapleural pressure of 5, 10, 15 mmHg and following results were obtained. 1) The insufflation of 5 to 15 mmHg of $CO_2$had no significant effect on the mean arterial pressure, heart rate, arterial oxygen saturation. 2) The end-tidal $CO_2$pressure rose from 31.00$\pm$1.67 mmHg to 38.49$\pm$1.82 mmHg at an intrapleural pressure of 15 mmHg(p<0.05). 3) The central venous pressure rose from 7.75$\pm$0.76 mmHg to 12.83$\pm$1.64 mmHg and 16.16$\pm$l.97mmHg at an intrapleural pressure of 10 and 15 mmHg(p<0.05). 4) The low pressure (<10 mmHg) insufflation is a safe adjunct to the conduct of thoracoscopic surgical procedures.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.4
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• pp.12-17
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• 2004

The PSP technique has been used to measure pressure distribution on model surfaces ins high-speed flows. The objective of this study is to develop a PSP technique which can be applied to low-speed aerodynamic flows. Four different PSP formulations including two porphyrins (PtOEP and PtTFPP) and two polymers (Poly(TMSP) and RTV-118) were tested and the performance of each combination was evaluated. In a static calibration, the luminescent intensity of the PSP coatings was measured from 0kPa to 11kPa with 0.5, 1, 2kPa increments. Among 4 PSP formulations tested, the combination of PtOEP and RTV-118 shows the best performance. The developed PSP technique was applied to an oblique impinging jet to measure the pressure field distribution on the impinging plate.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.600-602
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• 1995

Using the $O_2$ RIE process, 20{\mu}m$-height polyimide microstructures are fabricated. In LIGA-like process, metal microstructure can be formed by the electroplating using these polyimide microstructures as a plating mould. Reactive ion Etching technique using oxygen gas is used for the patterning of polyimide. The etching rate of the polyimide is increased with increased pressure and RF power. The anisotropic vertical sidewall can be obtained at low pressure, but the etched surface state is not so good yet. "Micrograss", which is formed during the RIE and disturbs uniform electroplating, can be removed effectively by the wet itching of the chromium sacrificial layer. More studies about the improvement of an etched surface state and the removal of microsgrass are needed.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.1
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• pp.26-29
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• 2006

Transparent ZnO thin films were prepared by KrF pulsed laser deposition (PLD) technique and applied to a bottom-gate type thin film transistor device as an active channel layer. A high conductive crystalline Si substrate was used as an metal-like bottom gate and SiN insulating layer was then deposited by LPCVD(low pressure chemical vapour deposition). An aluminum layer was then vacuum evaporated and patterned to form a source/drain metal contact. Oxygen partial pressure and substrate temperature were varied during the ZnO PLD deposition process and their influence on the thin film properties were investigated by X-ray diffraction(XRD) and Hall-van der Pauw method. Optical transparency of the ZnO thin film was analyzed by UV-visible phometer. The resulting ZnO-TFT devices showed an on-off ration of $10^6$ and field effect mobility of 2.4-6.1 $cm^2/V{\cdot}s$.

• Journal of the Korean institute of surface engineering
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• v.35 no.2
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• pp.113-121
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• 2002

We have investigated insulating properties of $SiO_2$ interlayer for the thin film strain gauge, which were prepared by RF magnetron sputtering method in various deposition conditions, such as Ar pressure, gas flow rates and sputtering gases. SEM, AFM and FT-IR techniques were used to analyze its structures and composition. As the Ar pressure and the flow rate increased, the insulating interlayer showed low insulating resistance due to its porous structure and defects. Oxygen deficiency in $SiO_2$ was decreased as fabricated by hydrogen reactive sputtering. We could enhance the surface mobility of sputtered adatoms by using Ar/$H_2$ sputtering gas and obtain a good surface roughness and insulating property. The optimum insulating resistance of 9.22 G$\Omega$ was obtained in Ar/30% $H_2$ mixed gas, flow rate 10sccm, and 1mTorr.