A Bandwidth-Enhanced Reconfigurable Slot Antenna

Woosung Lee,Hyungrak Kim,Young Joong Yoon 대한전자공학회 2005 ITC-CSCC :International Technical Conference on Ci Vol.2005 No.2

Cathode modification with solution-processed hybrid electron extraction layer for improved charge collection of planar heterojunction perovskite solar cells

Lee, Woosung,Choi, Jun,Jung, Jae Woong ELSEVIER 2017 ORGANIC ELECTRONICS Vol.51 No.-

<P><B>Abstract</B></P> <P>Optimal interface modification of perovskite solar cells is critical to achieve efficient and balanced charge transport and collection. We herein demonstrated that a solution-processed hybrid cathode interfacial layer composed of polyetyleneimine ethoxylate and a lithium quinolate complex improves photovoltaic performance of the planar heterojunction perovskite solar cells. The hybrid cathode modifier effectively lowered work function of ITO cathode, which afforded efficient electron transport and collection at ITO. Furthermore, surface roughness of ITO was significantly decreased, leading to enlarged grain size in densely-packed perovskite thin film. Consequently, the perovskite solar cells with hybrid electron extraction layer generated maximum power conversion efficiency up 15.21%, which is 25% improved value than that without hybrid electron extraction layer. Furthermore, highly-flexible flexible devices with a hybrid electron extraction layer exhibited a promising efficiency of 14.41%, demonstrating its potential for high performance perovskite solar cells.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Planar perovskie solar cells with PEIE-LiQ as an extraction layer was demonstrated. </LI> <LI> The device with a hybrid electron extraction layer showed power conversion efficiency up to 15.21%. </LI> <LI> The hybrid electron extraction layer was applied to flexible device, resulting in PCE up to 14.41%. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Analysis and Characterization of Dye-Based Black Matrix Film of Low Dielectric Constant Containing Phthalocyanine and Perylene Dyes.

Lee, Woosung,Choi, Jun,Kim, Se Hun,Park, Jongseung,Kim, Jae Pil American Scientific Publishers 2015 Journal of Nanoscience and Nanotechnology Vol.15 No.1

<P>For liquid crystal display black matrices of low dielectric constant, greenish zinc phthalocyanine dye and reddish perylene dye exhibiting high solubility and thermal stability were employed to fabricate dye-based black matrices. The spectral, optical, thermal and dielectric properties of the dye-based black matrices were tested, and the surfaces of them were investigated using field emission scanning electron microscopy and atomic force microscopy. The dye-based black matrices had sufficiently low dielectric constants and showed satisfactory thermal stability and weaker light absorption property compared with black matrices containing carbon black, due to the low solubility of the dyes and dye aggregations after a post-baking process.</P>

Science Diplomacy and APEC STI (Science, Technology and Innovation) Cooperation

Woosung Lee 한국APEC학회 2018 Journal of APEC Studies Vol.10 No.2

September 25 (2015). 193 governments took the historic step of adopting the 2030 Agenda and the Sustainable Development Goals (SDGs) at the UN Sustainable Development Summit. As countries came together with the goal of taking the world on a more sustainable pathway, it also became evermore clear the critical role of science, technology and innovation (STI) as a means of tackling some of the most pressing global issues in unconventional, cross-cutting ways. Among many of those global issues, historically as well as within the SDGs framework, climate change proves to be one of the direst issues needed to be tackled, especially through STI.Given the rapidly expanding impacts of climate change and hazardous weather activities, especially in the APEC region, economies are now in need of climate technologies that will allow more accurate and effective climate assessment and forecasting. In addition, given the exploitation of natural resources, the degradation of the environment and its resulting climate impacts, economies are in dire need of clean technology solutions and investments in sectors such as renewable energy, clean water and climate smart agriculture. Against such backdrop, it is imperative that APEC economies come together and continue their efforts on addressing climate change. And it is within such context in which the APEC Research and Technology (ART) Program, which is longstanding Korean initiative for APEC policy dialogue, plays a critical role. As one of the most effective policy dialogue platforms of PPSTI, the ART program has sought to address ways for APEC to facilitate cooperation on climate technology and SDGs issues. With this background, this paper discusses the APEC PPSTI agendas and history within the perspective of Science Diplomacy among APEC region.

Compact Rotman Lens with Size-Reduced Transition Structures between the Lens Body and the Connecting Lines

Woosung Lee,Youngsub Kim,Jaeheung Kim,Young Joong Yoon 한국전자파학회JEES 2013 Journal of Electromagnetic Engineering and Science Vol.13 No.2

This paper introduces a new design for a Rotman lens that has been proposed to minimize its size and provide a suitable design for a compact beamforming system. The size reduction is realized by minimizing the length of the transition structures, which are positioned between the lens body and the connecting lines. The proposed structure is much shorter than a conventional transition structure, which is a tapered line in general. As a result, a 45% size reduction can be achieved by using the proposed transition structure, compared to a typical Rotman lens with linearly tapered lines. Therefore, the proposed Rotman lens will be suitable for compact beamforming systems.

Fabrication and Characterization of Thin Film Perovskite Solar Cell Based on Textile Substrate

Woosung LEE,Jong Hyuk BAE,Jae Woong JUNG 한국고분자학회 2016 한국고분자학회 학술대회 연구논문 초록집 Vol.41 No.2

Analysis of Haematococcus pluvialis proteins associated with astaxanthin production

Woosung Lee(이우성),Jeong-Dong Kim(김정동),Choul-Gyun Lee(이철균) 한국생물공학회 2004 한국생물공학회 학술대회 Vol.2004 No.4

Compact Two-Layer Rotman Lens-Fed Microstrip Antenna Array at 24 GHz

Woosung Lee,Jaeheung Kim,Young Joong Yoon IEEE 2011 IEEE transactions on antennas and propagation Vol.59 No.2

<P>This paper presents a new design to realize a compact Rotman lens-fed antenna array. The lens-fed antenna has the form of two layers, which is a new approach to reducing the size of the Rotman lens. The approach is demonstrated at 24 GHz aiming for an automotive sensing radar. The lens consists of a top metal layer, a dielectric, a common ground, a dielectric, and a bottom metal layer, in sequential order. The layout of the lens body is placed on the bottom layer and the antennas are placed on the top layer. Both of them are electrically connected through slot transitions. This two-layer structure reduces not only the total size of the lens, but also the loss of the delay lines because the lines can be designed to be as short and straight as possible. The two-layer Rotman lens-fed antenna array is measured in terms of scattering parameters and beam patterns. From the scattering parameters, the power efficiencies of the beam port 1, 2, and 3 at 24 GHz are obtained as 32.3%, 48.5%, and 50.8%, respectively. The measured beam patterns show that the beam directions are -28.1°, -14.9°, 0°, 15.5°, and 28.6° and the beamwidths are 13.4°, 13.2°, 12.8°, 13.5°, and 13.0°. The measurements confirm that the compact two-layer Rotman lens has been successfully demonstrated.</P>

Endovascular Treatment to Stop Life-threatening Bleeding from Branches of the External Carotid Artery in Patients with Traumatic Maxillofacial Fracture

Woosung Lee,심유식,정준호 대한뇌혈관외과학회 2016 Journal of Cerebrovascular and Endovascular Neuros Vol.18 No.2

Objective : The purpose of this study was to report our preliminary experience with endovascular treatment (EVT) for life-threatening bleeding from branches of the external carotid artery (ECA) in patients with traumatic maxillofacial fractures. Materials and Methods : A total of 12 patients seen between March 2010 and December 2014 were included in this study. All subjects met the following criteria: 1) presence of maxillofacial fracture; 2) continuous blood loss from oronasal bleeding; and 3) EVT to stop bleeding. Various clinical factors were recorded for each patient and the correlations between those factors and clinical outcome (Glasgow Outcome Scale, GOS) were evaluated. Results : Four patients were injured in traffic accidents, five in falls, and three by assaults. Mean initial Glasgow Coma Scale (GCS) was 6.9 ± 2.1 and the lowest hemoglobin measured was mean 6.3 ± 0.9 g/dL. GOS at discharge was 4 in five patients, 3 in three patients, and 1 (death) in four patients. GOS on follow-up (mean 13.7 months) was 5 in two patients, 4 in three patients, and 3 in three patients. Initial GCS (p = 0.016), lowest systolic blood pressure (p = 0.011), and lowest body temperature (p = 0.012) showed a significant positive correlation with good clinical outcomes. The number of units of red blood cells transfused (p = 0.030), the number of units of fresh frozen plasma transfused (p = 0.013), and the time from arrival to groin puncture (p < 0.001) showed significant negative correlation with good clinical outcomes. Conclusion : It might be suggested that rapid transition to EVT could be preferable to struggling with other rescue strategies to stop life-threatening bleeding from branches of the ECA in patients with traumatic maxillofacial fractures.

Beamforming Lens Antenna on a High Resistivity Silicon Wafer for 60 GHz WPAN

Woosung Lee,Jaeheung Kim,Choon Sik Cho,Young Joong Yoon IEEE 2010 IEEE transactions on antennas and propagation Vol.58 No.3

<P>Wafer-scale beamforming lenses for future IEEE802.15.3c 60 GHz WPAN applications are presented. An on-wafer fabrication is of particular interest because a beamforming lens can be fabricated with sub-circuits in a single process. It means that the beamforming lens system would be compact, reliable, and cost-effective. The Rotman lens and the Rotman lens with antenna arrays were fabricated on a high-resistivity silicon (HRS) wafer in a semiconductor process, which is a preliminary research to check the feasibility of a Rotman lens for a chip scale packaging. In the case of the Rotman lens only, the efficiency is in the range from 50% to 70% depending on which beam port is excited. Assuming that the lens is coupled with ideal isotropic antennas, the synthesized beam patterns from the S-parameters shows that the beam directions are -29.3°, -15.1°, 0.2°, 15.2°, and 29.5 °, and the beam widths are 15.37°, 15.62°, 15.46°, 15.51°, and 15.63°, respectively. In the case of the Rotman lens with antenna array, the patterns were measured by using on-wafer measurement setup. It shows that the beam directions are -26.6°, -21.8°, 0°, 21.8°, and 26.6° . These results are in good agreement with the calculated results from ray-optic. Thus, it is verified that the lens antenna implemented on a wafer can be feasible for the system-in-package (SiP) and wafer-level package technologies.</P>