액체금속 입자 기반 신축 전극의 웨어러블 소자 적용

Steve Park(스티브 박) 한국고분자학회 2024 한국고분자학회 학술대회 연구논문 초록집 Vol.49 No.1

Design of Electronic Skin Capable of Differentiating Multiple Tactile Inputs for Wearable and Robotic Applications

Steve Park(스티브 박) 한국고분자학회 2019 한국고분자학회 학술대회 연구논문 초록집 Vol.44 No.1

Large-area formation of self-aligned crystalline domains of organic semiconductors on transistor channels using CONNECT

Park, Steve,Giri, Gaurav,Shaw, Leo,Pitner, Gregory,Ha, Jewook,Koo, Ja Hoon,Gu, Xiaodan,Park, Joonsuk,Lee, Tae Hoon,Nam, Ji Hyun,Hong, Yongtaek,Bao, Zhenan National Academy of Sciences 2015 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.112 No.18

<P><B>Significance</B></P><P>Solution-processed organic electronics are expected to pave the way for low-cost large-area electronics with new and exciting applications. However, realizing solution-processed organic electronics requires densely packed transistors with patterned and precisely registered organic semiconductors (OSCs) within the transistor channel with uniform electrical properties over a large area, a task that remains a significant challenge. To address such a challenge, we have developed an innovative technique that generates self-patterned and self-registered OSC film with low variability in electrical properties over a large area. We have fabricated highest density of transistors with a yield of 99%, along with various logic circuits. This work significantly advances organic electronics field to enable large-scale circuit fabrication in a facile and economical manner.</P><P>The electronic properties of solution-processable small-molecule organic semiconductors (OSCs) have rapidly improved in recent years, rendering them highly promising for various low-cost large-area electronic applications. However, practical applications of organic electronics require patterned and precisely registered OSC films within the transistor channel region with uniform electrical properties over a large area, a task that remains a significant challenge. Here, we present a technique termed “controlled OSC nucleation and extension for circuits” (CONNECT), which uses differential surface energy and solution shearing to simultaneously generate patterned and precisely registered OSC thin films within the channel region and with aligned crystalline domains, resulting in low device-to-device variability. We have fabricated transistor density as high as 840 dpi, with a yield of 99%. We have successfully built various logic gates and a 2-bit half-adder circuit, demonstrating the practical applicability of our technique for large-scale circuit fabrication.</P>

Artificial Skin Techniques: Skin Inspired Electronics

( Steve Park ) 한국피부장벽학회 2020 한국피부장벽학회지 Vol.22 No.1

Electronic skin are devices that mimic the tactile sensing properties of human skin. They have a variety of exciting applications such as 3D touch screens, wearable electronics for health monitoring, prosthetics, and robotics with human-like functionalities. Herein we propose the use of microporous structures to fabricate 1) highly sensitive, large dynamic range pressure sensors with low hysteresis and 2) strain sensors with no-response to applied pressure. Our pressure and strain sensors can easily be coated onto irregularly shaped 3-dimensional objects (e.g. robotic hand) via spray coating, or be attached to human joints, to detect bending motion. Furthermore, our sensor can differentiate between shear stress and normal pressure. We furthermore demonstrate fiber-based electronic-skin capable of detecting strain and harvesting energy from the surroundings via piezoelectric effect. Lastly, we introduce various strategies to process tactile signals in parallel, inspired from how tactile input is processed in human somatosensory system. These demonstrations make our sensors and signal processing systems highly unique and important for the future development of high performance electronic skin.

MUSE를 이용한 차세대 항공교통관제체계 시제 개발 방안

박세호(Seho Park),박태준(Taejun Park),윤석준(Steve Yoon) 한국항공우주학회 2018 한국항공우주학회 학술발표회 논문집 Vol.2018 No.11

Effect of acceptor doping on phase transitions of HfO₂ thin films for energy-related applications

Park, Min Hyuk,Schenk, Tony,Hoffmann, Michael,Knebel, Steve,Gä,rtner, Jan,Mikolajick, Thomas,Schroeder, Uwe Elsevier 2017 Nano energy Vol.36 No.-

<P><B>Abstract</B></P> <P>Fluorite structured HfO<SUB>2</SUB> or ZrO<SUB>2</SUB> thin films have been intensively studied for memory- and energy-related applications since their ferroelectricity was first reported in 2011. The phase transition between the nonpolar tetragonal and the polar orthorhombic phase in these new ferroelectric materials is believed to be promising for energy harvesting, energy storage and solid state cooling. The temperature dependent phase transition and resulting strong pyroelectric and electrocaloric effect have been reported for Si-doped HfO<SUB>2</SUB> and (Hf,Zr)O<SUB>2</SUB> thin films. In this study, the effect of acceptor (Al and Gd) doping into HfO<SUB>2</SUB> thin films on their temperature dependent phase transition was systematically examined. The phase transitions in Al- and Gd-doped HfO<SUB>2</SUB> thin films were much broader compared to Si-doped HfO<SUB>2</SUB> and (Hf,Zr)O<SUB>2</SUB> films. The maximum adiabatic temperature change (ΔT) values of Al- and Gd-doped HfO<SUB>2</SUB> film were 5.7 and 3.1K, respectively. A giant negative electrocaloric effect with ΔT of −7.4K could be observed for Al-doped HfO<SUB>2</SUB>. The various factors which can potentially affect the phase transitions of HfO<SUB>2</SUB> films, such as dopant size, grain size distribution, spatial dopant distribution, and oxygen vacancy distribution were carefully examined to understand the different phase transition behavior. From the various factors, the distribution of oxygen vacancies is suggested as the origin of the different phase transitions of HfO<SUB>2</SUB> films doped with trivalent and tetravalent dopants.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Phase transition of Al- and Gd-doped HfO<SUB>2</SUB> films are reported for the first time. </LI> <LI> The effect of acceptor doping on the phase transition of fluorite ferroelectrics is investigated in depth. </LI> <LI> The energy harvesting and storage as well as electrocaloric effect of Al- and Gd-doped HfO<SUB>2</SUB> thin films is examined and compared to other materials. </LI> </UL> </P> <P><B>Graphic abstract</B></P> <P>[DISPLAY OMISSION]</P>

The Hidden Catalyst for Industrial Convergence between the MMOG Industry and the Online Broadcasting Industry in South Korea

Park, Jae-Hwan,Evans, Steve,Kim, Young Roak World Association for Triple Helix and Future Stra 2014 Journal of Contemporary Eastern Asia Vol.13 No.2

This paper explores the convergence process by focusing on the massively multiplayer online game(MMOG) industry and the online broadcasting industry in South Korea. In doing so, the paper seeks to establish the concept of Hidden catalysts for the integration process between the two industries and explore the roles of the Hidden catalysts in triggering the industry's transition. Further, the modified multi-level socio-technical model we applied in our research allows us both to understand each industry's development towards convergence in various dimensions and also to focus on the activities of the Hidden catalysts. In assessing the role of Hidden catalysts in industry convergence, we found that Hidden catalysts depend on two essential features: first, appropriate technology leading to the new industry dominance; and second, managerial capabilities to deal with conflicts among other new interest groups, to harmonise with government initiatives for industry development and to create new value in the integrated market to please the demand of mixed customers.

Metal–Organic Framework “Swimmers” with Energy-Efficient Autonomous Motility

Park, Jun H.,Lach, Slawomir,Polev, Konstantin,Granick, Steve,Grzybowski, Bartosz A. American Chemical Society 2017 ACS NANO Vol.11 No.11

<P>Placed at a water/air interface, particles of porphyrin-based MOFs (metal–organic frameworks) cut from large-area films display efficient, multiple-use autonomous motility powered by release of solvents incorporated in the MOF matrix and directionality dictated by their shapes. The particles can be refueled multiple times and can achieve speeds of <I>ca.</I> 200 mm·s<SUP>–1</SUP> with high kinetic energy per unit of chemical “fuel” expended (>50 μJ·g<SUP>–1</SUP>). Efficiency of motion depends on the nature of the fuel used as well as the microstructure and surface wettability of the MOF surface. When multiple movers are present at the interface, they organize into “open” structures that exhibit collective, time-periodic motions.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2017/ancac3.2017.11.issue-11/acsnano.7b04644/production/images/medium/nn-2017-04644e_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn7b04644'>ACS Electronic Supporting Info</A></P>

Policy Effects of Secondhand Smoke Exposure in Public Places in the Republic of Korea: Evidence from PM_2.5 levels and Air Nicotine Concentrations

Park, Eun Young,Lim, Min Kyung,Yang, Wonho,Yun, E Hwa,Oh, Jin-Kyoung,Jeong, Bo Yoon,Hong, Soon Yeoul,Lee, Do-Hoon,Tamplin, Steve Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.12

Objective: The purpose of this study was to evaluate secondhand smoke (SHS) exposure inside selected public places to provide basic data for the development and promotion of smoke-free policies. Methods: Between March and May 2009, an SHS exposure survey was conducted. $PM_{2.5}$ levels and air nicotine concentrations were measured in hospitals (n=5), government buildings (4), restaurants (10) and entertainment venues (10) in Seoul, Republic of Korea, using a common protocol. Field researchers completed an observational questionnaire to document evidence of active smoking (the smell of cigarette smoke, presence of cigarette butts and witnessing people smoking) and administered a questionnaire regarding building characteristics and smoking policy. Results: Indoor $PM_{2.5}$ levels and air nicotine concentrations were relatively higher in monitoring sites where smoking is not prohibited by law. Entertainment venues had the highest values of $PM_{2.5}$(${\mu}g/m^3$) and air nicotine concentration(${\mu}g/m^3$), which were 7.6 and 67.9 fold higher than those of hospitals, respectively, where the values were the lowest. When evidence of active smoking was present, the mean $PM_{2.5}$ level was 104.9 ${\mu}g/m^3$, i.e., more than 4-fold the level determined by the World Health Organization for 24-hr exposure (25 ${\mu}g/m^3$). Mean indoor air nicotine concentration at monitoring sites with evidence of active smoking was 59-fold higher than at sites without this evidence (2.94 ${\mu}g/m^3$ vs. 0.05 ${\mu}g/m^3$). The results were similar at all specific monitoring sites except restaurants, where mean indoor $PM_{2.5}$ levels did not differ at sites with and without active smoking evidence and indoor air nicotine concentrations were higher in sites without evidence of smoking. Conclusion: Nicotine was detected in most of our monitoring sites, including those where smoking is prohibited by law, such as hospitals, demonstrating that enforcement and compliance with current smoke-free policies in Korea is not adequate to protect against SHS exposure.

Transmission Electron Microscopy Study of Stacking Fault Pyramids Formed in Multiple Oxygen Implanted Silicon-on-Insulator Material

Park, Ju-Cheol,Lee, June-Dong,Krause, Steve J. Korean Society of Microscopy 2012 Applied microscopy Vol.42 No.3

The microstructure of various shapes of stacking fault pyramids (SFPs) formed in multiple implant/anneal Separation by Implanted Oxygen (SIMOX) material were investigated by plan-view and cross-sectional transmission electron microscopy. In the multiple implant/anneal SIMOX, the defects in the top silicon layer are confined at the interface of the buried oxide layer at a density of ${\sim}10^6\;cm^{-2}$. The dominant defects are perfect and imperfect SFPs. The perfect SFPs were formed by the expansion and interaction of four dissociated dislocations on the {111} pyramidal planes. The imperfect SFPs show various shapes of SFPs, including I-, L-, and Y-shapes. The shape of imperfect SFPs may depend on the number of dissociated dislocations bounded to the top of the pyramid and the interaction of Shockley partial dislocations at each edge of {111} pyramidal planes.