Improved Performance of Polymer:Polymer Solar Cells by Doping Electron‐Accepting Polymers with an Organosulfonic Acid

Nam, Sungho,Shin, Minjung,Kim, Hwajeong,Ha, Chang‐,Sik,Ree, Moonhor,Kim, Youngkyoo WILEY‐VCH Verlag 2011 Advanced functional materials Vol.21 No.23

<P><B>Abstract</B></P><P>The performance of polymer:polymer solar cells that are made using blend films of poly(3‐hexylthiophene) (P3HT) and poly(9,9‐dioctylfluorene‐co‐ benzothiadiazole (F8BT) is improved by doping the F8BT polymer with an organosulfonic acid [4‐ethylbezenesulfonic acid (EBSA)]. The EBSA doping of F8BT, to form F8BT‐EBSA, is performed by means of a two‐stage reaction at room temperature and 60°C with various EBSA weight ratios. The X‐ray photoelectron spectroscopy measurement reveals that both sulfur and nitrogen atoms in the F8BT polymer are affected by the EBSA doping. The F8BT‐EBSA films exhibit huge photoluminescence quenching, ionization potential shift toward lower energy, and greatly enhanced electron mobility. The short‐circuit current density of solar cells is improved by ca. twofold (10 wt.% EBSA doping), while the open‐circuit voltage increases by ca. 0.4 V. Consequently, the power conversion efficiency was improved by ca. threefold, even though the optical density of the P3HT:F8BT‐EBSA blend film is reduced by 10 wt.% EBSA doping due to the nanostructure and surface morphology change.</P>

Slope Based Intelligent 3D Disaster Simulation Using Physics Engine

Kim, Joo-Chang,Jung, Hoill,Kim, Sungho,Chung, Kyungyong Kluwer Academic Publishers 2016 WIRELESS PERSONAL COMMUNICATIONS Vol. No.

<P>In the modern society, the forms of disasters are getting larger and more diverse by abnormal weather phenomena due to rapid social changes. As human and economic damage is increasing by these disasters, interest in disaster observation and prevention is increasing and studies have been carried out in various fields. In order to minimize disaster damage, National Disaster Information Center provides disaster-related information such as disaster situations, risk index, local situation and so on. At present, however, various descriptive studies on action tips in the event of a disaster, disaster alert, disaster communications network have been in progress but there are few studies on prediction or simulation for preventing disasters etc. Therefore, this paper proposes a slope-based intelligent 3D disaster simulation using a physics engine. The proposed method is to infer a variety of disaster situations that may occur in reality through ontology and apply it to 3D simulation. Disaster situation ontology constitutes context information of outside, inside, disasters etc. and generates rule bases using Jena 2.0 inference engine. Inference results are derived in the form of XML and applicable to a variety of devices. The expression of 3D simulation virtual space is divided into interior and exterior. Interior constitutes the index information based on actually measured terrain and then expresses it into 3D compound type terrain data. Exterior expresses six planes into a hexahedron by using Sky Box technique. Simulation operates object collision, movement, surroundings etc. in real time by using a physics engine and represents a disaster situation in 3D virtual space by using particles function. Based on ontology based context awareness, environment context information on slope, including landslides, snow, rain, fogs, fire, explosion, and smoke, is developed into the slope based intelligent 3D disaster simulation. As a result, depending on geomorphic characteristics, disaster management service can realistically and visually be offered to users in 3D virtual reality. In addition, it is possible to experimentally apply disaster situations virtually through 3D virtual reality, and thereby judge their potential risk.</P>

Abrupt Morphology Change upon Thermal Annealing in Poly(3-Hexylthiophene)/Soluble Fullerene Blend Films for Polymer Solar Cells

Shin, Minjung,Kim, Hwajeong,Park, Jiho,Nam, Sungho,Heo, Kyuyoung,Ree, Moonhor,Ha, Chang-Sik,Kim, Youngkyoo WILEY-VCH Verlag 2010 Advanced Functional Materials Vol.20 No.5

<P>The in situ morphology change upon thermal annealing in bulk heterojunction blend films of regioregular poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C<SUB>61</SUB> (PCBM) is measured by a grazing incidence X-ray diffraction (GIXD) method using a synchrotron radiation source. The results show that the film morphology—including the size and population of P3HT crystallites—abruptly changes at 140 °C between 5 and 30 min and is then stable up to 120 min. This trend is almost in good agreement with the performance change of polymer solar cells fabricated under the same conditions. The certain morphology change after 5 min annealing at 140 °C is assigned to the on-going thermal transition of P3HT molecules in the presence of PCBM transition. Field-emission scanning electron microscopy measurements show that the crack-like surface of blend films becomes smaller after a very short annealing time, but does not change further with increasing annealing time. These findings indicate that the stability of P3HT:PCBM solar cells cannot be secured by short-time annealing owing to the unsettled morphology, even though the resulting efficiency is high.</P> <B>Graphic Abstract</B> <P>The morphology of P3HT:PCBM blend films, one of the most widely used material blends in polymer solar cells, is monitored using in situ grazing angle X-ray diffraction (GIXD). The study reveals abrupt changes in the nanostructure with annealing time (see image, OOP = out-of-plane), which is in good agreement with variations in device performance (PCE = power conversion efficiency; FF = fill factor). <img src='wiley_img_2010/1616301X-2010-20-5-ADFM200901655-content.gif' alt='wiley_img_2010/1616301X-2010-20-5-ADFM200901655-content'> </P>

Regulation of transferrin recycling kinetics by PtdIns[4,5]P ₂ availability

Kim, Sunyun,Kim, Hyunmyung,Chang, Belle,Ahn, Namhui,Hwang, Suha,Di Paolo, Gilbert,Chang, Sunghoe,Kim, Sunyun,Kim, Hyunmyung,Chang, Belle,Ahn, Namhui,Hwang, Suha,Di Paolo, Gilbert,Chang, Sunghoe Federation of American Society for Experimental Bi 2006 The FASEB Journal Vol.20 No.13

<P>Phosphatidylinositol 4,5-bisphosphate (PtdIns[4,5]P2) is a phosphoinositide involved in a variety of cellular functions, including signal transduction, organelle trafficking, and actin dynamics. Although the role of PtdIns[4,5]P2 in endocytosis is well established, the precise trafficking steps relying on normal PtdIns[4,5]P2 balance in the endosomal pathway have not yet been elucidated. Here we show that decrease in intracellular PtdIns[4,5]P2 levels achieved by the overexpression of the 5-phosphatase domain of synaptojanin 1 or by siRNA knock-down of PIP5Ks expression lead to severe defects in the internalization of transferrin as well as in the recycling of internalized transferrin back to the cell surface in COS-7 cells. These defects suggest that PtdIns[4,5]P2 participates in multiple trafficking and/or sorting events during endocytosis. Coexpression of the PtdIns[4,5]P2 synthesizing enzyme, PIP5KI gamma, was able to rescue these endocytic defects. Furthermore, decreased levels of PtdIns[4,5]P2 caused delays in rapid and slow membrane recycling pathways as well as a severe backup of endocytosed membrane. Taken together, our results demonstrate that PtdIns[4,5]P2 availability regulates multiple steps in the endocytic cycle in non-neuronal cells.</P>

Chemiosmotic Control of Renin Secretion

Chang, Sunghoe,Jeong, Sueyoung,Jang, Yeon Jin,Park, Chun Sik 울산대학교 의과대학 1992 울산의대학술지 Vol.1 No.1

본 실험에서는 토끼의 신피질 Slices를 이용하여 renin분비와 세포 대사과정 사이의 연관관계를 살펴 보았다. 2-deoxy-D-glucose로 해당과정을 억제한 경우에는 renin분비에 변화가 없는 반면, 6-aminonicotinamide를 사용하여 hexose monophoshate shunt를 억제했을 때는 renin분비가 촉진되었다. 그러나, 미토콘드리아에서 APT생성을 억제한다고 알려진 KCN과 carbonylcyanide-m-chlorophenylhydrazone(이하 CCCP)는 renin분비를 억제하였다. 세포배양액에서 Ca²+을 제거할 경우 KCN에 의한 renin분비억제 효과가 상실되는 것으로 보아 KCN은 세포내 Ca²+을 증가시키고 이에 다른 2차적인 현상으로 renin분비가 억제되는 것으로 생각된다. 반면, CCCP에 의한 억제효과는 세포외액에서 Ca²+을 제거하거나 혹은 calmodulin antagonist인 calmiddazolium을 첨가하여도 영향을 받지 않으므로, CCCP는 막내외의 H+-농도차를 없애므로써 renin분비를 억제하는 것으로 봉ㄴ다. 그러나 H+-ATPasedjr제제인 bafilomycin A1은 효과가 없었다. 따라서 막내외의 H+ 농도 차이와 renin분비사이의 관계를 H+/K+ exchange ionophore nigericin을 사용하여 살펴보았다. Renin분비가 nigericin에 의해 크게 촉진되는 것으로 보아 H+이나 다른 일가양이온의 농도차가 renin분비에 중요한 역할을 함을 알 수 있었다. 막 내외 H+ 농도차에 의해 세포내 산성 vesicle내에 축적될 것으로 생각되는 ammonium chloride, benzylamine, chloroquine, methylamine등의 약염기도 renin분비를 촉진하였다. 신피질 slices를 hypo-osmotic medium에 배양시킨 경우 renin분비가 가역적으로 촉진되었다. 이상의 결과는 ATP는 renin granular membrane에 있어서의 H+ 혹은 다른 이온의 농도차를 유발 또는 유지함으로써 renin분비에 간접적으로 영향을 미칠 가능성을 시사한다. 또한, 이러한 이온의 농도차는 osmotic swelling에 의한 분비와 연관되어 있을 것으로 생각된다.

Rejuvenation of IN738LC gas-turbine blades using hot isostatic pressing and a series of heat treatments

Sungho Yang,윤정한,Chang-Sung Seok 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.11

The maintenance of the gas turbine blades is important because these blades are operated in harsh conditions. Therefore, nickel-based superalloys that offer excellent performances in high-temperature conditions are typically used, and the blades are inspected and replaced based on the manufacturer’s maintenance standards. However, the service life can be extended by refurbishing the blades that have exceeded their warranty life, based on the manufacturer criteria. In this study, 10 rejuvenation conditions that consist of ‘hot isostatic pressing and series of heat treatment’ were applied to the blades that operated in domestic environments and had exceeded their warranty life. First, through microstructure analysis, by comparing the shape of the gamma prime phase according to the change of the full solution temperature, the optimal full solution temperature was selected to be 1200 °C or more and less than 1220 °C. Based on this, the tensile properties according to the presence or absence of HIP process and the detailed heat treatment conditions were evaluated, and the optimal rejuvenation conditions was selected by comparing tensile strength, yield strength, and elongation values. Finally, to verify the selected rejuvenation condition, the creep durability was evaluated, and it was confirmed that the creep life of the used material with a reduced creep life of 40 % compared to the new material was restored similarly to the new material.

Upper and Lower Limits of Process Capability Ratio

Sungho Chang,Gary D. Herrin 대한산업공학회 1991 대한산업공학회 추계학술대회논문집 Vol.1991 No.10

Dynamic modeling and fuzzy control for a small tiltrotor unmanned aerial vehicle

Chang, Sungho,Bang, Hyochoong,Lee, Wonsuk,Park, Bumjin SAGE Publications 2013 Proceedings of the Institution of Mechanical Engin Vol.227 No.9

<P>Dynamic modeling and fuzzy control of a tiltrotor unmanned aerial vehicle are presented. In order to design a full-conversion flight controller for a tiltrotor unmanned aerial vehicle, the dynamic characteristics of a small tiltrotor unmanned aerial vehicle during helicopter-to-airplane conversion is investigated. A six-degree-of-freedom nonlinear equation of motion using powered wind tunnel test data is developed based on a Bell Model 301 tiltrotor research aircraft. The time-varying characteristics of the conversion maneuver, over which system dynamics change rapidly, are handled by a Takagi–Sugeno fuzzy control approach in both longitudinal and lateral axes. Simulation results indicate that a small tiltrotor unmanned aerial vehicle exhibits nacelle tilt during the backward conversion flight from airplane to helicopter mode.</P>

SNX9 regulates tubular invagination of the plasma membrane through the interaction with actin cytoskeleton and dynamin

Chang, Sunghoe 이화여자대학교 세포신호전달연구센터 2007 고사리 세포신호전달 심포지움 Vol. No.9

Dynamic membrane remodeling for cellular trafficking or motility is known to be achieved by the interplay between lipids and proteins. Sorting nexin 9(SNX9), which contains SH3, LC, and PX domain, is a member of the sorting nexin family of proteins. The C-terminal part of SNX9 contains a putative BAR(Bin-Amphiphysin-Rvs) domain, which displays a coiled-coil nature with a characteristic set of conserved hydrophobic, aromatic and hydrophilic residues. BAR domain proteins such as amphiphysin and endophilin, is known to be involved in membrane deformation and vesicle budding during clathrin-mediated endocytosis. Here we tested the role of SNX9 BAR domain during clathrin pit formation. SNX9 interacts with dynamin and N-WASP, and induces tubular invaginations originating from the plasma membranes. The C-terminal BAR domain as well as LC and PX domains is required for tubular membrane invagination. BAR domains of two SNX9 dimerizes with each other to form V shaped dimmer to sense and/or induce membrane bending. The ability of SNX9 BAR domain to induce tubular invaginations is enhanced by disruption of the actin cytoskeleton and is antagonized by dynamin. Our results suggest that SNX9 coordinates tubular membrane invagination and fission events through the interaction with actin cytoskeleton and dynamin.

40 kg급 틸트-덕트 수직이착륙 비행체의 아이언버드 비행시험

장성호(Sungho Chang),조암(Am Cho),최성욱(Seongwook Choi) 한국항공우주학회 2017 한국항공우주학회 학술발표회 논문집 Vol.2017 No.4