• Journal of Electrical Engineering and Technology
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• 제11권4호
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• pp.939-942
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• 2016

One of the most important characteristic curves of a solar cell is its current density-voltage (J-V) curve under AM1.5G insolation. Solar cell can be considered as a semiconductor diode, so a diode equivalent model was used to estimate its parameters from the J-V curve by numerical simulation. Active layer plays an important role in operation of a solar cell. We investigated the effect thicknesses and defect densities (N_d) of the active layer on the J-V curve. When the active layer thickness was varied (for N_d = 8×10¹⁷ cm^-3) from 800 nm to 100 nm, the reverse saturation current density (J_o) changed from 3.56×10^-5 A/cm² to 9.62×10^-11 A/cm² and its ideality factor (n) changed from 5.28 to 2.02. For a reduced defect density (N_d = 4×10¹⁵ cm^-3), the n remained within 1.45≤n≤1.92 for the same thickness range. A small increase in shunt resistance and almost no change in series resistance were observed in these cells. The low reverse saturation current density (J_o = 9.62×10^-11 A/cm²) and diode ideality factor (n = 2.02 or 1.45) were observed for amorphous silicon based solar cell with 100 nm thick active layer.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.122.2-122.2
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• 2015

n-type 실리콘은 p-type과 비교하여 더 높은 소수캐리어 lifetime 으로 금속 불순물에 대하여 더 좋은 내성을 갖는다. 고효율 실리콘 태양전지를 위하여 p-type 웨이퍼를 n-type으로 교체하여 빛을 조사했을 때, 광전자들이 형성되어 p-type과 비교하여 더 좋은 lifetime 안정성을 갖는다. n-type 태양전지의 전면 전극은 AgAl paste로 형성하였다. AgAl 페이스트는 소성 온도와 밀접하게 관련되어 전극의 접합 깊이에 영향을 미친다. p+ emitter 층에 파고드는 금속 접촉의 최적화된 깊이는 접촉 저항에 영향을 미치는 중요한 요소이다. 본 연구에서는 소성 조건을 변화시킴으로써, 금속 깊이의 효과적인 형성을 위한 소성 조건을 최적화하였다. $670^{\circ}C$ 이하의 온도에서 소성을 진행 하였을 때, 충분한 접촉 깊이를 형성하지 못하여 높은 접촉저항을 갖는다. 소성 온도가 증가함에 따라, 접촉 저항은 감소하였다. 최적 소성 온도 $865^{\circ}C$에서 측정된 접촉저항은 $5.99mWcm^2$이다. $900^{\circ}C$ 이상에서 contact junction은 emitter를 통과하여 실리콘과 결합하였다. 그 결과로 접촉저항 shunt가 발생한다.

• 한국전자파학회논문지
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• 제20권10호
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• pp.1091-1096
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• 2009

본 논문에서는 공진 MTM-TL(Metamaterial Transmission Line) 등가 회로를 이용하여 방사 및 회로 파라미터의 추출 식을 제시하였다. 특히 개방 또는 단락 상태에서 방사 소자인 직렬 $R_0$와 병렬 $G_0$를 EM 시뮬레이션 또는 측정을 통해 얻은 S-parameterd(|$S_{11}$|)를 이용하여 추출한다, EM 시뮬레이션의 결과, 추출한 파라미터를 이용한 회로 시뮬레이션의 결과 그리고 측정 결과가 매우 일치함을 확인하였다.

• Journal of Chest Surgery
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• 제35권1호
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• pp.64-67
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• 2002

Eisenmenger's 증후군은 체-폐순환의 이상연결통로를 가진 환자에서 폐혈류량의 과다로 발생한 폐혈관저항의 증가로 인해 우-좌단락이 발생한 경우를 말한다. 이식이 시작된 초기에는 심폐동시이식이 유일한 치료방법 이었으나, 폐이식만으로도 수술 후에 우심실의 기능이 개선됨이 밝혀지면서 최근에는 양측 폐이식만으로도 좋은 결과가 보고되고 있다. 저자들은 큰 동맥관 개존증으로 인한 Eisenmenger's증후군이 동반된 34세 여자 환자에게 순차적 양측 폐이식을 성공적으로 시행하였기에 문헌 고찰과 함께 보고하는 바이다.

• Journal of Chest Surgery
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• 제20권1호
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• pp.22-29
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• 1987

From Sep. 1978 to Aug. 1986, 44 cases of Fontan operation were performed at Seoul National University Hospital. 1] The diagnoses were TA in 13 [38.6%], UVH in 21 [47.79`], DORV in 3 [6.8%], TGA in 2 [4.5%] and C-ECD with DORY in 1[2.3%]. 2] There were 20 operative deaths [44.5%]. 3] The operative risk factors were early date of operation between 1978 and 1983, young age below 3 years old, direct atriopulmonary anastomosis without roofing, and postoperative high CVP above 25cmH,O. But the relation between operative mortality and various cardiac diseases was absent. 4] survived patients were followed from 1 to 54 months except 3 patients who were lost to follow up. 16 patients were in functional class I and 1 in class II, 2 of the above 17 patients were reoperated due to residual right to left shunt. In remained 4 patients, 3 patients persisted cyanosis after operation and 1 patients died 1 month postoperatively due to pulmonary embolism. 5] As 4 result, the Fontan procedure can be done with a good result for tricuspid atresia and other complex lesions. The operative mortality can be reduced further with a correct anatomical diagnosis preoperatively, rigid operative criteria to pulmonary vascular resistance, direct atriopulmonary anastomosis with roofing, and use of `Venous Assist Device` postoperatively in low cardiac output patients.

• Journal of Chest Surgery
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• 제20권3호
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• pp.520-527
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• 1987

Clinical analysis was performed of 89 secundum type atrial septal defect patients operated on during the period from July, 15th, 1981 to March, 1987 in the Thoracic and Cardiovascular Surgery Department of Pusan National University Hospital. Secundum type ASD was 2`I.0% among all of congenital heart diseases operated in the same period. The age distribution of patients ranged from 3 to 41 years and sex ratio, male to female was 1.23 to 1.0. Common symptoms were exertional dyspnea 64.0%, frequent upper respiratory infection 43.8%, cyanosis 10.1% and fatigue 7.9%. The mean value of cardiac catheterization data of the group of ASD combined with another cardiovascular anomalies was compared with that of only ASD group. The amount of shunt showed not statistically significant difference between two groups [P>0.05] but pulmonary arterial pressure and pulmonary vascular resistance of combined group was significantly higher than that of only ASD group [P<0.02, P<0.01]. The difference of mean hemodynamic data between the age group below 20 years and above 21 years was not statistically significant [P>0.05]. All cases were operated under cardiopulmonary bypass. Among these 51 were closed directly and 38 were applied Dacron patch. Two most common associated cardiac anomalies were pulmonary stenosis [8 cases, 9.0%] and VSD [8 cases, 9.0%]. The most frequent postoperative complication was wound infection, One patient died of low cardiac output on 10th postoperative day and the overall operative mortality was 1.1%

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.128.2-128.2
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• 2011

스테인레스 스틸 유연기판 위에 플라즈마 화학기상 증착법 (plasma enhanced chemical vapor deposition)을 이용하여 nip 구조의 미세결정질 실리콘 박막 태양전지 (microcrystalline silicon thin film solar cell)를 제조하고 i ${\mu}c$-Si:H광 흡수층과 p ${\mu}c$-Si:H 사이에 i a-Si:H 버퍼 층을 삽입하여 i/p 계면특성을 개선하고 이에 따른 태양전지 성능특성 변화를 조사하였다. ${\mu}c$-Si:H 박막으로 이루어진 i/p 계면에서의 구조적, 전기적 결함은 태양전지 내에서 생성된 캐리어의 재결합과 shunt resistance 감소를 초래하여 개방전압 (open circuit voltage) 및 곡선 인자 (fill factor)를 감소시키는 것으로 알려졌다. 제조된 미세결정질 실리콘 박막 태양전지는 SUS/Ag/ZnO:Al/n ${\mu}c$-Si:H/i ${\mu}c$-Si:H/p ${\mu}c$-Si:H 구조로 제작되었으며 i/p 계면 사이의 i a-Si;H 버퍼층 두께를 변화시키고 이에 따른 태양전지의 특성을 조사하였다. 태양전지의 구조적, 전기적 특성 변화는 Scanning Electron Microscope (SEM), UV-visible-nIR spectrometry, Photo IV와 Dark IV를 통하여 조사하였다.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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• pp.272-275
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• 2000

We investigated a resistive superconducting fault current limiter (SFCL) fabricated using YBCO thin films on 2-inch diameter sapphire substrates. Nearly identical SFCL units were prepared and tested. The units were connected in series and parallel to increase the current and voltage ratings. A serial connection of the units showed significantly unbalanced power dissipation between the units. This imbalance was removed by introducing a shunt resistor to the firstly quenched unit. Parallel connection of the units increased the current rating. An SFCL module of 4 units in parallel, each of which has minimum quench current 25 Ap, was produced and successfully tested at a 220 V circuit. From the resistance increase, we estimated that the film temperature increases to 200 K in 5 msec, and 300 K in 120 msec. Successive quenches revealed that this system is stable without degradation in the current limiting capability under such thermal shocks as quenches at 220 V.

• Journal of Chest Surgery
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• 제22권1호
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• pp.25-31
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• 1989

Forty-five patients, aged 16 months to 15.5 years mean 69 months, with a wide variety of cardiac malformations underwent the modified Fontan operation between Sep. 1986 to Aug. 1988. Nineteen patients had previously undergone palliative operations mainly modified B-T shunt. Twenty patients had a mean pulmonary artery pressure greater than 15 mmHg, with nine operative deaths. Thirteen patients had anomalies of systemic venous connection and seven patients had anomalies of pulmonary venous connection. There were eighteen patients under the age 4 years and fifteen of them survived [83.3%]. Eighteen patients had a pulmonary vascular resistance [PVR] more than 2.5U/m, and nine died [50%] whereas two of twenty-three with a PVR less than 2.5U/m died[8.6%]. PVR and anomalies of pulmonary venous connection had a significant influence on survival, but age and anomalies of systemic venous connection did not. Amount of pleural effusion drained postoperatively and PVR had positive linear correlation. Pulmonary artery pressure was not an independent predictor of outcome and pulmonary artery pressure alone should not contraindicate a Fontan procedure if PVR is low. In general, the Fontan operation should be done at a younger age less than 4 year to avoid ventricular dysfunction due to long-standing exposure to hypoxia.

• Current Photovoltaic Research
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• 제2권2호
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• pp.69-72
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• 2014

We investigated current-voltage (I-V) and capacitance (C)-V characteristics of solution-processed thin film solar cells, consisting of $Cu(In,Ga)S_2$ and $CuInS_2$ stacked absorber layers. The ideality factors, extracted from the temperature-dependent I-V curves, showed that the tunneling-mediated interface recombination was dominant in the cells. Rapid increase of both series- and shunt-resistance at low temperatures would limit the performance of the cells, requiring further optimization. The C-V data revealed that the carrier concentration of the $CuInS_2$ layer was about 10 times larger than that of the $Cu(In,Ga)S_2$ layer. All these results could help us to find strategies to improve the efficiency of the solution-processed thin film solar cells.