• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2010년도 추계학술발표논문집 1부
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• pp.73-75
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• 2010

층간 절연막으로 사용 가능한 SiOC 박막에 대하여 유전상수가 낮아지는 원인을 이온에 의한 분극과 전자에 의한 분극에 대하여 측정하였다. MIS 구조를 이용하여 전형적인 C-V 측적법에 의하여 유전상수를 구하였으며, 굴절률을 측정하여 전자에 의한 분극의 효과에 의한 유전상수를 측정하고 서로 비교하였다. SiOC 박막의 화학적인 특성은 FTIR 분석을 이용하였으며, FTIR 분석에서 디컨벌류션한 데이터는 탄소의 함량에 대한 변화를 구하였다. 탄소의 함량변화는 굴절률의 변화와 비슷한 경향성을 나타내었으나, 유전상수와는 반비례하였다. 전자에 의한 분극의 효과는 유전상수가 떨어지는 것에 큰 영향을 주지는 않았으며, 이온에 의한 분극의 효과가 SiOC 박막의유전상수를 낮게 하는 효과가 더욱 크게 나타났다.

• 대한수학회논문집
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• 제33권1호
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• pp.361-369
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• 2018

For a given graph G = (V, E), a set $D{\subseteq}V(G)$ is said to be an outer-connected vertex edge dominating set if D is a vertex edge dominating set and the graph $G{\backslash}D$ is connected. The outer-connected vertex edge domination number of a graph G, denoted by ${\gamma}^{oc}_{ve}(G)$, is the cardinality of a minimum outer connected vertex edge dominating set of G. We characterize trees T of order n with l leaves, s support vertices, for which ${\gamma}^{oc}_{ve}(T)=(n-l+s+1)/3$ and also characterize trees with equal domination number and outer-connected vertex edge domination number.

• Current Photovoltaic Research
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• 제2권3호
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• pp.135-139
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• 2014

Different power output of solar cells can be observed at high-temperature regions such as desert areas. In this study, performance dependence on operating temperature of crystalline silicon solar cells with different emitter types was analyzed. Based on the light current-voltage (LIV) measurement, temperature coefficients of short-circuit current density ($J_{SC}$), open-circuit voltage ($V_{OC}$), fill factor (FF) and power conversion efficiency were measured and compared for two groups of crystalline silicon solar cells with different emitter types. One group had homogeneously doped (conventional) emitter and another selectively doped (selective) emitter. Varying the operating temperature from 25 to 40, 60, and $80^{\circ}C$, LIV characteristics of the cells were measured and the properties of saturation current densities ($J_0$) were extracted from dark current-voltage (DIV) curve. From the DIV data, effect of temperature on the performance of the solar cells with different electrical structures for the emitter was analyzed. Increasing the temperature, both emitter structures showed a slight increase in $J_{SC}$ and a rapid degradation of $V_{OC}$. FF and power conversion efficiency also decreased with the increasing temperature. The degrees of $J_{SC}$ increase and $V_{OC}$ degradation for two groups were compared and explained. Also, FF change was explained by series and shunt resistances from the LIV data. It was concluded that the degradation of solar cells shows different values at different temperatures depending on the emitter type of solar cells.

• 한국재료학회지
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• 제24권7호
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• pp.375-380
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• 2014

Solar cells exhibit different power outputs in different climates. In this study, the temperature dependence of open-circuit voltage(V-oc), short-circuit current(I-sc), fill factor(FF) and the efficiency of screen-printed single-crystal silicon solar cells were studied. One group was fabricated with homogeneously-doped emitters and another group was fabricated with selectively-doped emitters. While varying the temperature (25, 40, 60 and $80^{\circ}C$), the current-voltage characteristics of the cells were measured and the leakage currents extracted from the current-voltage curve. As the temperature increased, both the homogeneously-doped and selectively-doped emitters showed a slight increase in I-sc and a rapid degradation of V-oc. The FF and efficiency also decreased as temperature increased in both groups. The temperature coefficient for each factor was calculated. From the current-voltage curve, we found that the main cause of V-oc degradation was an increase in the intrinsic carrier concentration. The temperature coefficients of the two groups were compared, leading to the idea that structural effects could also affect the temperature dependence of current-voltage characteristics.

• 한국진공학회지
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• 제22권4호
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• pp.211-217
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• 2013

$PCDTBT:PC_{71}BM$과 $PTB7:PC_{71}BM$을 유기고분자 활성층 재료로 이용한 Bulk Hetero-Junction (BHJ) 구조의 유기박막태양전지를 플라스틱 기판 위에 각각 제작하여, 시간변화에 따른 단락전류밀도($J_{SC}$), 개방전압($V_{OC}$), 곡선인자(FF) 및 전력변환효율(PCE) 등 출력특성의 변화에 대해 고찰하였다. 유기박막태양전지의 출력특성 파라메터는 시간 경과에 따라 모두 감소하는 경향을 나타내었으며, 특히 개방전압의 감소폭이 컸다. 이러한 개방전압 감소의 원인은 빛에 대한 장시간의 노출과 산소를 포함하는 수분과의 접촉에 의한 LUMO 준위와 HOMO 준위 차의 감소가 그 원인이라 생각되며, 그 메커니즘에 대해 고찰하였다. 또한 유기박막태양전지 소자의 직렬 및 병렬 저항 값은 감소하다가 다시 증가하는 경향을 보였다. 이는 LUMO 준위와 HOMO 준위 차가 감소함에 의한 것과 공액 고분자 활성층 내부에서의 열적과정 손실에 기인하여 전극과 고분자의 계면에서의 접촉저항의 증가 때문이라고 생각된다. 유기박막태양전지의 전력변환효율은 초기에 급격한 감소를 보이다가 시간이 지날수록 감소폭이 차츰 둔화되어 한계치에 도달한 후, 포화되는 경향을 보였다. 이것이 유기박막태양전지가 실제 구동에서 발생시킬 수 있는 최소 출력특성값인 것으로 판단된다.

• Asian Pacific Journal of Cancer Prevention
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• 제17권12호
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• pp.5315-5320
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• 2016

Purpose: Tumor cell growth and sensitivity to chemotherapy depend on many factors, among which insulin-like growth factors (IGFs) may play important roles. The aim of the present study was to evaluate the levels of insulin-like growth factors (IGFs) and IGF binding proteins (IGFBPs) in primary tumors and ascites as predictors of response to neoadjuvant chemotherapy in ovarian cancer (OC) patients. Materials and Methods: Tumor tissue samples and ascitic fluid were obtained from 59 patients with advanced OC. The levels of IGF-I, IGF-II, IGFBP-3, IGFBP-4 and PAPP-A were determined using ELISA kits. Taking into account the data on expression of these IGF-related proteins and outcome, logistic regression was performed to identify predictors of response to neoajuvant chemotherapy. Results: Human ovarian tumors expressed IGFs, IGFBP-3, IGFBP-4 and PAPP-A and these proteins were also present in ascites fluid and associated with its volume. IGFs and IGFBPs in ascites and soluble PAPP-A might play a key role in ovarian cancer progression. However, levels of proteins of the IGF system in tumors were not significant predictors of objective clinical response (oCR). Univariate analysis showed that the level of IGF-I in ascites was the only independent predictor for oCR. Conclusion: The level of IGF-I in ascites was shown to be an independent predictor of objective clinical response to chemotherapy for OC patients treated with neoadjuvant chemotherapy and debulking surgery.

• 폴리머
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• 제37권6호
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• pp.694-701
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• 2013

프탈이미드 유도체와 티오펜 단량체들을 이용하여 새로운 고분자인 poly((5,5-(2-butyl-5,6-bisdecyloxy-4,7-dithiophen-2-yl-isoindole-1,3-dione))-alt-(2,5-thiophene))(T-TI24T)를 Stille법을 이용하여 합성하였다. T-TI24T의 수평균 분자량은 86500 g/mol로 매우 높으며 클로로포름, 1,2-디클로로벤젠, 톨루엔과 같은 용매에 매우 잘 용해된다. 또한 $380^{\circ}C$까지 매우 우수한 열적 안정성을 갖고 있다. T-TI24T는 꽤 낮은 호모에너지 준위(-5.33 eV)를 갖고 있다. 서로 다른 T-TI24T와 (6)-1-(3-(methoxycarbonyl)-{5}-1-phenyl[5,6]-fullerene(PCBM)의 무게비를 갖는 블렌드를 광활성층으로 하는 태양전지를 제작하여 특성을 살펴본 결과 고분자와 PCBM의 비율이 1:3일 때 가장 최적화된 결과를 보였으며, 이 때 광전변환 효율과 개방전압은 각각 0.199%와 0.99였다. T-TI24T 기반 태양전지들은 비록 매우 작은 광전변환 효율을 갖지만 잘 알려진 P3HT:PC61BM으로 구성된 태양전지와 비교해 큰 매우 큰 개방전압을 갖는다(약 0.5 V).

• 한국수소및신에너지학회논문집
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• 제25권3호
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• pp.289-296
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• 2014

Here, we have studied the effect of water added electrolyte on the photovoltaic performance of dye-sensitized solar cells (DSSCs). It was found that open-circuit voltage ($V_{oc}$) increased and short-circuit current density ($j_{sc}$) decreased with the increase of the amount of added water in the electrolyte of the DSSCs. Electrochemical impedance spectroscopy (EIS) study showed that the electrolyte with added water shifted the dye loaded $TiO_2$ conduction band upward that eventually increased $V_{oc}$ of the cells. On the other hand, the upward shift of $TiO_2$ conduction band decreased the driving force for the electron injection from the lowest unoccupied molecular orbital (LUMO) of the dye molecules to the conduction band of $TiO_2$ that resulted in decreased $j_{sc}$.

• Bulletin of the Korean Chemical Society
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• 제34권2호
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• pp.411-414
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• 2013

In order to enhance the photovoltaic property of the CdS/CdSe co-sensitized quantum dot sensitized solar cells (QDSSCs), the surface of nanoporous $TiO_2$ photoanode was modified by ultrathin $Al_2O_3$ layer before the deposition of quantum dots (QDs). The $Al_2O_3$ layer, dip-coated by 0.10 M Al precursor solution, exhibited the optimized performance in blocking the back-reaction of the photo-injected electrons from $TiO_2$ conduction band (CB) to polysulfide electrolyte. Transient photocurrent spectra revealed that the electron lifetime (${\tau}_e$) increased significantly by introducing the ultrathin $Al_2O_3$ layer on $TiO_2$ surface, whereas the electron diffusion coefficient ($D_e$) was not varied. As a result, the $V_{oc}$ increased from 0.487 to 0.545 V, without appreciable change in short circuit current ($J_{sc}$), thus inducing the enhancement of photovoltaic conversion efficiency (${\eta}$) from 3.01% to 3.38%.

• Current Photovoltaic Research
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• 제7권3호
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• pp.61-64
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• 2019

In this study, we investigate organic-inorganic hybrid solar cells with a very simple three-layer structure (Al/n-Si/PEDOT:PSS). The performance of hybrid solar cells is optimized by controlling the sheet resistance and optical transmittance of the PEDOT:PSS layers. As the thickness of the PEDOT:PSS layer decreases, the optical absorption of the n-Si increases, which greatly improves the short-circuit current density ($J_{SC}$) of devices, but the increase in sheet resistance leads to a decrease in the open-circuit voltage ($V_{OC}$) and the fill factor (FF). The solar cell with the 180-nm thick PEDOT:PSS layer shows a highest efficiency of 8.45% ($V_{OC}$: 0.435 V, $J_{SC}$: $33.7mA/cm^2$, FF: 57.5%). Considering these results, it is expected that the optimizing process for the sheet resistance and transmittance of the PEDOT:PSS layer is essential for producing high-efficiency organic-inorganic hybrid solar cells and will serve as an important basis for achieving low-cost, high-efficiency solar cells.