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Lim, Ju Won,Wang, Huan,Choi, Chi Hun,Quan, Li Na,Chung, Kyungwha,Park, Won-Tae,Noh, Yong-Young,Kim, Dong Ha Elsevier 2019 Journal of Power Sources Vol.438 No.-
<P><B>Abstract</B></P> <P>Developing perovskite solar cells (PSCs) with high-efficiency and a low-temperature process has great potential for the realization of the scalable, economic, and roll-to-roll based renewable energy conversion devices. ZnO has been recognized as the promising electron transport layer (ETL) that may overcome the limitations of the conventional TiO<SUB>2</SUB>. However, methylammonium lead iodide (MAPbI<SUB>3</SUB>) perovskite is prone to decomposition at the ZnO surface, which hinders the development of simple one-step deposition of perovskite, resulting in the limited photovoltaic performance. Herein, we report interlayer mediated efficient ETLs for viable flexible PSCs. The utilization of polyethyleneimine ethoxylated layer on ZnO prevents the direct contact between the perovskite and ETLs, avoiding the photoactive layer decomposition. Thus, interlayer-mediated PSCs show higher efficiency with enhanced stability by decreasing the electron transport barrier. As a result, the PSC employing tailor-designed ETL interfaces exhibited average power conversion efficiency (PCE) of 15.8%, which was superior by 25.4% to that of a control device (12.6%). With our strategy, we further demonstrated PSCs on flexible substrates which exhibit an average PCE of 11.9% under low-temperature fabrication. The new interface engineering strategy may pave the way to the realization of high performance, easy-to-process, and large-area perovskite optoelectronics.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Universal interface engineering technique for highly stable flexible PSCs. </LI> <LI> The in-depth investigation into the enhanced stability and high-efficiency PSCs. </LI> <LI> Interlayer mediated PSC exhibits 15.8% PCE, superior by 25.4% to control device. </LI> <LI> Low-temperature processed PSCs for the next-generation renewable energy sources. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Coupling of ent-Cyclic Peroxide and Ircinol A, Two Biologically Active Natural Marine Products
Lim, Chi-Won,Kim, Yeun-Kye,Jang, Mi-Soon,Park, Jin-Il,Park, Hee-Yeun The Korean Society of Fisheries and Aquatic Scienc 2006 Fisheries and Aquatic Sciences Vol.9 No.4
An acidic ent-cyclic peroxide was isolated from a sponge, Plakotis sp., and showed activity against leishmaniasis and pathogenic fungi. To improve the activity of this compound, we coupled the acidic ent-cyclic at the C1 position of ircinol A. Compound 3 exhibited significant activity against Leishmania mexican a and fungi with $IC_{50}$ values of 0.7 and $0.3-34{\mu}g/mL$, respectively. The yield of compound 3 was 98%.
Lim, Ju Won,Wang, Huan,Choi, Chi Hun,Kwon, Hannah,Quan, Li Na,Park, Won-Tae,Noh, Yong-Young,Kim, Dong Ha Elsevier 2019 Nano energy Vol.57 No.-
<P><B>Abstract</B></P> <P>In this work, we developed the perovskite photodiodes based on the dimensionality-reduced quasi two-dimensional (Q-2D) photoactive layer structure by incorporating phenylethylammonium iodide (PEAI) into methylammonium lead iodide (MAPbI<SUB>3</SUB>), which effectively enhanced both the crystalline phase and the ambient stability of the perovskite. The Q-2D perovskite photodiode exhibited a dark current of 1.76 × 10<SUP>−7</SUP> A/cm<SUP>2</SUP>, resulting in the detectivity (D*) of 2.20 × 10<SUP>12</SUP> J and responsivity of 0.53 A/W, which is among the highest performance levels without the voltage bias (0 V) due to the systematically optimized perovskite phase resulting in the reduced leakage current. In addition, the current density of Q-2D perovskite photodiode maintained 76% of the initial level current density even after 80 days in the ambient condition, compared to 15% of 3D perovskite photodiode control sample. Such superior performance and stability were mainly attributed to the enhanced degree of crystallization of the Q-2D perovskites, which was confirmed by X-ray diffraction and grazing incidence wide-angle X-ray scattering (GIWAXS) measurement. Also, the improved stability of Q-2D perovskite films was confirmed by both lifetime test and atomic force microscopy studies where the negligible number of pinholes was observed in the quasi-2D perovskite films while considerable deformations were found in the 3D perovskites photodiode. Our study suggests a simple and robust protocol for the development of stable and high-performance perovskite photodetectors via dimensional and constitutional optimization of conventional perovskites for the practical usage of perovskite in the photodiode applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The Q-2D perovskite photodiode exhibited the D* of 2.20 × 10<SUP>12</SUP> J and R of 0.53 A/W without the voltage bias (0 V). </LI> <LI> The current density of Q-2D perovskite photodiode maintained 76 % of the initial level while 15 % for the 3D one. </LI> <LI> Grazing incidence wide-angle X-ray scattering (GIWAXS) analysis revealed the origin of the stability improvement. </LI> <LI> Quasi-2D perovskite materials can be promising candidates for stable, tunable and flexible optoelectronic applications. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Dimensionality-controlled perovskite photodiodes with improved stability were systematically fabricated while retaining the comparable electrical performance of conventional three-dimensional perovskites. The quasi-2D perovskite photodetector exhibited an improved detectivity of 2.20 × 10<SUP>12</SUP> J performance and maintained 76% of initial level while the performance of three-dimensional perovskite photodetector remained only 15% after 80 days. Our study suggests a facile solution for the poor stability of the three-dimensional perovskite, with a potential for the development of highly-stable perovskite optoelectronics.</P> <P>[DISPLAY OMISSION]</P>
Seismic performance evaluation of a three-dimensional unsymmetrical reinforced concrete building
Lim, Hyun-Kyu,Kang, Jun Won,Lee, Young-Geun,Chi, Ho-Seok Techno-Press 2016 Multiscale and multiphysics mechanics Vol.1 No.2
Reinforced concrete (RC) structures require advanced analysis techniques for better estimation of their seismic responses, especially in the case of exhibiting complex three-dimensional coupling of torsional and flexural behaviors. This study focuses on validating a numerical approach for evaluating the seismic response of a three-dimensional unsymmetrical RC structure through the participation in the SMART 2013 international benchmark program. The benchmark program provides material properties, detailed drawings of the RC structure, and input ground motions for the seismic response evaluation. In this study, nonlinear constitutive models of concrete and rebar were formed and local tests were conducted to verify the constitutive models in finite element analysis. Elastic calibration of the finite element model of the SMART 2013 RC structure was performed by comparing numerical and experimental results in modal and linear time history analyses. Using the calibrated model, nonlinear earthquake analysis and seismic fragility analysis were performed to estimate the behavior and vulnerability of the RC structure with various ground motions.
Chi, Liang,Jang, Won-Mee,Nguyen, Lim The Korea Institute of Information and Commucation 2012 Journal of communications and networks Vol.14 No.3
We propose self-encoded spread spectrum with two different iterative detection methods in multi-channel communication. The centralized iterative detection outperforms the iterative detection distributed over multiple channels. The results show that self-encoded spread spectrum with the centralized iterative detection is an excellent candidate for cognitive radio network.
( Chi Hoon Lee ),( Hyun Phil Shin ),( Joung Il Lee ),( Kwang Ro Joo ),( Jae Myung Cha ),( Jung Won Jeon ),( Jun Uk Lim ),( Joon Ki Min ),( Dong Hee Kim ),( Sung Wook Kang ),( Hyun Jun Joung ) 대한간학회 2013 Clinical and Molecular Hepatology(대한간학회지) Vol.19 No.4
Background/Aims: To identify the predicting factors of present hepatitis C virus (HCV) infection among patients with positivity for antibodies to HCV (anti-HCV). Methods: We analyzed patients who showed positive enzyme immunoassay (EIA) results and performed an HCV RNA test as a confirmatory test at Kyung Hee University Hospital at Gangdong from June 2006 to July 2012. The features distinguishing the groups with positive and negative HCV RNA results were reviewed. Results: In total, 490 patients were included. The results of the HCV RNA test were positive and negative in 228 and 262 patients, respectively. The index value of anti-HCV, mean age, platelet counts, total bilirubin, prothrombin time international normalized ratio, albumin and alanine transaminase (ALT) levels differed significantly between the two groups. On multivariable analysis, an index value of anti-HCV >10 [odds ratio (OR)=397.27, P<0.001), ALT >40 IU/L (OR=3.64, P=0.001), and albumin <3.8 g/dL (OR=2.66, P=0.014) were related to present HCV infection. Conclusions: Although EIA is not a quantitative test, considering the anti-HCV titer with ALT and albumin levels may be helpful in predicting present of HCV infection.