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Gas-Pressure-Assisted Modified One-Step Deposition for Hybrid Perovskite Solar Cells
Jo, Mansik,Cho, Seulki,Jang, Jihun,Song, Sangwoo,Moon, Kyoung-Sook,Koo, Sang-Mo,Moon, Byungmoo American Scientific Publishers 2017 Journal of nanoelectronics and optoelectronics Vol.12 No.12
<P>In recent years, hybrid organic-inorganic perovskites have attracted much attention as promising light absorbers. Herein, the gas pressure during spin coating for a perovskite layer is introduced as a parameter for perovskite solar cells. We adopt gas pressure engineering to improve the perovskite film morphology without overgrown crystals and pin-holes. As a result, compared to 8.95% efficiency of conventional two step fabrication, perovskite solar cells based on gas-pressure-assisted method showed similar efficiency of 8.48% but increased the current density from 16.28 mA/cm(2) to 15.69 mA/cm(2), even though it reduced processing time and steps. These findings will provide important guidelines for the fabrication of low-cost perovskite solar cells.</P>
Jo, Mansik,Bae, Seunghwan,Oh, Injong,Jeong, Ji-hun,Kang, Byungsoo,Hwang, Seok Joon,Lee, Seung S.,Son, Hae Jung,Moon, Byung-Moo,Ko, Min Jae,Lee, Phillip American Chemical Society 2019 ACS NANO Vol.13 No.11
<P>Stretchability and areal coverage of active devices are critical design considerations of stretchable or wearable photovoltaics and photodetections where high areal coverages are required. However, simultaneously maximizing both properties in conventional island-bridge structures through traditional two-dimensional manufacturing processes is difficult due to their inherent trade-offs. Here, a 3D printer-based strategy to achieve extreme system stretchability and high areal coverage through combining fused deposition modeling (FDM) and flexible conductive nanocomposites is reported. Distinguished from typical approaches of using conductive filaments for FDM which have a flexibility dilemma and conductivity trade-offs, the proposed axiomatic approach to embed a two-dimensional silver nanowire percolation network into the surfaces of flexible 3D printed structures offers sufficient conductivity and deformability as well as additional benefits of electrical junction enhancement and encapsulation of silver nanowires. Kirigami/origami-pattern-guided three-dimensional arrangements of encapsulated interconnections provide efficient control over stretchability and areal coverage. The suggested process enables a perovskite solar module with an initial areal coverage of ∼97% to be electrically and mechanically reversible with 400% system stretchability and 25 000% interconnect stretchability under the 1000 cycle test, by folding down or hiding the origami-applied interconnects under the islands. This 3D printing strategy of potentially low cost, large size capabilities, and high speed is promising for highly flexible future energy conversion applications.</P> [FIG OMISSION]</BR>
기계학습 알고리즘을 이용한 반도체 테스트공정의 불량 예측
장수열,조만식,조슬기,문병무,Jang, Suyeol,Jo, Mansik,Cho, Seulki,Moon, Byungmoo 한국전기전자재료학회 2018 전기전자재료학회논문지 Vol.31 No.7
Because of the rapidly changing environment and high uncertainties, the semiconductor industry is in need of appropriate forecasting technology. In particular, both the cost and time in the test process are increasing because the process becomes complicated and there are more factors to consider. In this paper, we propose a prediction model that predicts a final "good" or "bad" on the basis of preconditioning test data generated in the semiconductor test process. The proposed prediction model solves the classification and regression problems that are often dealt with in the semiconductor process and constructs a reliable prediction model. We also implemented a prediction model through various machine learning algorithms. We compared the performance of the prediction models constructed through each algorithm. Actual data of the semiconductor test process was used for accurate prediction model construction and effective test verification.
우리 나라의 성인의 혈중 납 농도 분포 연구 : 공단지역 및 도시지역 거주 주민들을 대상으로
정용,양지연,이지호,황만식,조성준 한국환경독성학회 1999 환경독성보건학회지 Vol.14 No.4
Lead (Pb) is ubiquitous in the urban environment and is a well-known toxic element. It may cause adverse health effects on hematopoietic system, peripheral and central nervous systems, kidney functions, and others. In recent decades, lead concentration in blood has been widely used one of indicators for lead exposure and risk evaluation. In this study, we determined the blood-lead levels in general populations of Korea, and investigated the relationship among blood-lead levels, sociobehavioral factors, and lead concentrations in the contacted environments such as ambient air, drinking water, and foods. The study subjects consisted of volunteers who had lived in the residential or industrial area in Korea. Information about gender, age, living area, occupation, smoking, heat system, and dietary habits, etc was collected using a self-reported questionnaires. The lead concentrations of environments were collected by literature search to the study area. Participated subjects in industrial area were 726 and their blood-lead levels were 8.58μg/dl for males and 6.26μg/dl for female in average. The other subjects in residential area were 317 and their blood-lead levels were 4.58μg/dl for males and 3.49μg/dl for female in average. The distribution of blood-lead level in the industrial subjects was well fitted to the log-normal distribution and that in the residential subjects was well fitted to the normal distribution. Blood-lead levels in both area were affected by gender, smoking habit, age and residence duration except age in industrial area and residence duration in residential area. It was identified that 30% of blood-lead level was contributed from the inhalation of ambient air in the industrial area, and 8.4% of blood-lead level was from that in the residential area. From this study, it would be suggested for the health risk assessment and management of lead pollution concerns in urban, industrial and rural areas.
Super-resolution visible photoactivated atomic force microscopy
Lee, Seunghyun,Kwon, Owoong,Jeon, Mansik,Song, Jaejung,Shin, Seungjun,Kim, HyeMi,Jo, Minguk,Rim, Taiuk,Doh, Junsang,Kim, Sungjee,Son, Junwoo,Kim, Yunseok,Kim, Chulhong Nature Publishing Group 2017 Light, science & applications Vol.6 No.11
<P>Imaging the intrinsic optical absorption properties of nanomaterials with optical microscopy (OM) is hindered by the optical diffraction limit and intrinsically poor sensitivity. Thus, expensive and destructive electron microscopy (EM) has been commonly used to examine the morphologies of nanostructures. Further, while nanoscale fluorescence OM has become crucial for investigating the morphologies and functions of intracellular specimens, this modality is not suitable for imaging optical absorption and requires the use of possibly undesirable exogenous fluorescent molecules for biological samples. Here we demonstrate super-resolution visible photoactivated atomic force microscopy (pAFM), which can sense intrinsic optical absorption with ~8 nm resolution. Thus, the resolution can be improved down to ~8 nm. This system can detect not only the first harmonic response, but also the higher harmonic response using the nonlinear effect. The thermoelastic effects induced by pulsed laser irradiation allow us to obtain visible pAFM images of single gold nanospheres, various nanowires, and biological cells, all with nanoscale resolution. Unlike expensive EM, the visible pAFM system can be simply implemented by adding an optical excitation sub-system to a commercial atomic force microscope.</P>
Lee, Jaeyul,Park, Jaeseok,Faizan Shirazi, Muhammad,Jo, Hosung,Kim, Pilun,Wijesinghe, Ruchire Eranga,Jeon, Mansik,Kim, Jeehyun Elsevier 2019 Infrared physics & technology Vol.98 No.-
<P><B>Abstract</B></P> <P>We demonstrated a preliminary research to investigate the feasible <I>in vivo</I> utilization of swept-source optical coherence tomography (SS-OCT) system with 1310 nm wavelength band to obtain morphological visualizations and human gingival sulcus depth measurements. Apart from the cross-sectional analysis, pixel intensity based OCT image classification algorithm is developed to identify the depth of gingival sulcus quantitatively. A total of 43 sites from the periodontal tissues of five healthy individuals were imaged <I>in vivo</I> by using the OCT system. Two periodontal tissues were right and left maxillary central incisors, while the other four periodontal tissues were left and right mandibular central incisors and later incisors. The developed classification algorithm could measure the gingival sulcus depths, which are 1.15 ± 0.21 mm of the maxilla and 1.06 ± 0.27 mm of the mandible. The averaged total depths obtained by the system was 1.10 ± 0.26 mm. Hence, the gingival sulcus depth could be quantitatively measured by using the swept-source OCT system with the developed image classification algorithm as well as revealing a structural visualization, which ultimately confirmed the potential applicability for gingival sulcus depth real-time assessment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SS-OCT was utilized to visualize human gingival sulcus <I>in vivo</I> for the depth identification. </LI> <LI> The quantitative measurement was enhanced by applying the developed OCT image classification algorithm. </LI> <LI> Total of 43 sites from the periodontal tissues of five healthy individuals was imaged. </LI> <LI> The classification of gingival sulcus was helpful to confirm the depth of maxilla and mandible regions. </LI> <LI> The proposed method can be anticipated that provides a powerful tool to the periodontal-OCT applications. </LI> </UL> </P>