• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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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.

• 멤브레인
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• 제9권1호
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• pp.25-35
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• 1999

산소농축공기 제조용 폴리설폰 실관막에 대한 산소.질소의 수착 및 투과실험을 수행하였다. 폴리설폰 실관막에 대한 산소의 수착량이 질소의 수착량보다. 1.5배 ~2 배 높았다. 저압영역(약 3 kgf/$cm^2$이하) 에서는 Henry-type 수착량 ($C_D$)이 전체수착량의 약 15% 이었으며, Langmuir 수착이 약 85%이었다. 고압영역(약 3 kgF/$cm^2$이상)에서는 Langmuir 수착은 거의 포화되어 일정한 값에 도달하였으며, Henry 용해에 의한 수착($C_D$ = $k_D$.p) 의 증가에 의하여 전체 수착량이 증가하였다. 산소와 질소의 수착은 dual-mode sorption 모델을 만족시켰다. 산소의 투과 활성화에너지(Ep)가 질소보다 컸고, 이상분리인자 (${O_2}/{N_2}$)는 2~4를 나타내었으나 , 혼합물의 실제 분리인자는 1.7 ~2.2로 낮아졌다.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2001년도 Proceedings of 6th International Joint Symposium on Microeletronics and Packaging
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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.

• 대한물리의학회지
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• 제17권4호
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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.

• 센서학회지
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• 제10권4호
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• pp.222-231
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• 2001

$SnO_2$의 물성을 $Fe_2O_3$ 첨가량, 산소분압, CO 기체농도, 그리고 온도의 함수로서 관찰하였다. 시편은 후막인쇄 기법으로 알루미나 기판 위에 제조하였다. $700^{\circ}C$/6h 소성한 시편들의 $Fe_2O_3$첨가량에 따른 미세구조와 입자분포의 차이는 거의 없었다. $Fe_2O_3$를 첨가하지 않은 $SnO_2$의 전기적 성질은 소성온도가 낮은 경우와 산소분압이 낮은 경우에 전도성이 높게 측정되었다. $Fe_2O_3$를 첨가한 $SnO_2$의 전도성은 측정온도 증가로 증가하지만 $Fe_2O_3$ 첨가량 증가로 전도성은 감소하였다. 산소분압 의존성은 $Fe_2O_3$ 첨가로 감소하였다. CO 가스에 대한 기체 센서 특성 중 감도는 $350^{\circ}C$, 0.1 mol% $Fe_2O_3$를 첨가한 경우에 가장 높았고, 재현성 및 응답성도 양호하게 나타났다.

• Journal of Chest Surgery
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• 제29권7호
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• pp.723-727
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• 1996

흉강경수술시 적 절한 수술시야를 확보하는 것이 가장 중요하다. 이때 이산화탄소를 주입하여 폐를 허 탈시키고 환자의 위 치를 변경함으로서 수술 시야를 좋게 할 수 있다. 그러나 최근 보고에 의하면 돼지에 서 흥강경 시행시 이산화탄소를 주입하여 좋지 않은 혈역학적인 변화가 일어날 수 있다고 보고하고 있 다. 그래서 본 저자는 흥강경을 시행한 12명의 환자를 대상으로 조작전, 일측환기시, 흥강내압이 SmrnHg, 10minHg, 15rnrnHg 변화시 평균혈압, 심박동수, 중심정맥 압, 동맥산소포화도, 환기말이산화 탄소분압등의 혈역학적 인 변화를 조사하여 다음과 같은 결과를 얻었다. 1. 조작전 기준치와 일측폐환기시 및 흥강내압 변화시 측정한 평균혈압, 심박동수, 동맥산소포화도 사이 에 유의한 변동이 없었다. 2. 환기말 이산화탄소 분압은 기준치 31.00$\pm$1.67mmHg 에서 흥강내압 15 mmHg증가시 38.49$\pm$1.82 mmHg(p<0.05) 로의 변화가 관찰되었다. 3. 중심정맥압은 기준치 7.75$\pm$0.76 minHg 에서 흥강내압 10mmHg 증가시 12.83$\pm$1.64minHg, 15 mmHg 증가시 16.16$\pm$ 1.97 mmHg(p<0.05)로 의미있는 변화가 관찰되 었다 4. 흥강경수술시 혈역학적 변화없이 \ulcorner술시야를 확보하기 위한 이산화탄소압력은 10mmHg이하가 적당 할 것으로 생각한다.

• 한국항공우주학회지
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• 제32권4호
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• pp.12-17
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• 2004

고속 유동 속에 놓인 모델 표변의 압력분포를 정량적으로 측정하기 위해 PSP 기술이 사용되고 있다. 본 연구에서는 아음속 유동에 적용 가능한 PSP 기술을 개발하였다. 2가지의 백금계열 (PtOEP와 PtTFPP)의 발광분자와 2 가지의 폴리머 (Poly(TMSP)와 RTV-118)를 사 용하여 4가지의 PSP 조합을 만들어 그 성능을 확인하였다. 압력변화에 따른 PSP의 발광강 도를 측정하기 위해 $0{\sim}11kPa$까지 0.5, 1, 2kPa썩 압력을 증가시키면서 정적보정실험을 수행하였다. 4가지의 PSP 조성 중에 PtOEP 와 RTV-118의 조합이 가장 좋은 성능을 보였다. 충돌평판에 작용하는 압력장 분포를 측정하기 위하여 경사충돌분류에 본 연구에서 개발된 PSP 기술을 응용하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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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.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권1호
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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 $cm^2/V{\cdot}s$.

• 한국표면공학회지
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• 제35권2호
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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.