http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Backscattering measurement from a single microdroplet
Jungwoo Lee,Jin Ho Chang,Jong Seob Jeong,Changyang Lee,Shia-Yen Teh,Lee, A,Shung, K IEEE 2011 and Frequency Control Vol.58 No.4
<P>Backscattering measurements for acoustically trapped lipid droplets were undertaken by employing a P[VDF-TrFE] broadband transducer of f-number = 1, with a bandwidth of 112%. The wide bandwidth allowed the transmission of the 45 MHz trapping signal and the 15 MHz sensing signal using the same transducer. Tone bursts at 45 MHz were first transmitted by the transducer to hold a single droplet at the focus (or the center of the trap) and separate it from its neighboring droplets by translating the transducer perpendicularly to the beam axis. Subsequently, 15 MHz probing pulses were sent to the trapped droplet and the backscattered RF echo signal received by the same transducer. The measured beam width at 15 MHz was measured to be 120 μ m. The integrated backscatter (IB) coefficient of an individual droplet was determined within the 6-dB bandwidth of the transmit pulse by normalizing the power spectrum of the RF signal to the reference spectrum obtained from a flat reflector. The mean IB coefficient for droplets with a 64 μ m average diameter (denoted as cluster A) was -107 dB, whereas it was -93 dB for 90-μm droplets (cluster B). The standard deviation was 0.9 dB for each cluster. The experimental values were then compared with those computed with the T-matrix method and a good agreement was found: the difference was as small as 1 dB for both clusters. These results suggest that this approach might be useful as a means for measuring ultrasonic backscattering from a single microparticle, and illustrate the potential of acoustic sensing for cell sorting.</P>
Jungwoo Lee,Taehee Park,Jongtaek Lee,Mira Jang,Seungjin Lee,Heesu Kim,한성환,이휘건 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.8
Single-walled carbon nanotubes (SWNTs) and C60-encapsulated SWNTs (C60@SWNTs) are introduced to Rusensitized photoelectrochemical cells (PECs), and photocurrents are compared between two cells, i.e., an RuL2(NCS)2/DAPV/SWNTs/ITO cell and an RuL2(NCS)2/DAPV/C60@SWNTs/ITO cell. [L = 2,2'- bipyridine-4,4'-dicarboxylic acid, DAPV = di-(3-aminopropyl)-viologen, and ITO = indium-tin oxide] The photocurrents are increased by 70.6% in the presence of C60@SWNTs. To explain the photocurrent increase, the reverse-field emission method is used, i.e., RuL2(NCS)2/DAPV/SWNTs/ITO cell (or RuL2(NCS)2/DAPV/ C60@SWNTs/ITO cell) as an anode and a counter electrode Pt as a cathode in the external electric field. The improved field emission properties, i.e., β (field enhancement factor) and emission currents in the reverse-field emission with C60@SWNTs indicate the enhancement of the PEC electric field, which implies the improvement of the electron transfer rate along with the reduced charge recombination in the cell.
2018년 기업가정신 모니터링 사업 : 혁신창업생태계 연구
이정우(Jungwoo Lee),김선우(Sunwoo Kim),김영환(Younghwan Kim),이윤준(Yoonjun Lee),백서인(Seoin Baek),권기환(Kihwan Kwon),모미령(Meeryung Mo),정효정(Hyojung Jung),이승재(Seungjae Lee) 과학기술정책연구원 2019 정책연구 Vol.- No.-
This study monitors the recent entrepreneurship and startup ecosystem to propose timely evidence-based policies for the activation of entrepreneurship focusing on innovative startups. The research questions mainly as follows: What is the status and environment of Korea"s innovative startups? What are the obstacles to establish innovative startups in Korea? The research was conducted at multi-level of national, firm, and individual levels. First, at the national level, using secondary data on 57 entrepreneurship components of 32 countries, international entrepreneurship index newly designed by STEPI have been compared with Korea. Particularly, in consideration of the distinct characteristics of Korea, weight factor adopts the components derived from Analytical Hierarchy Process (AHP) by experts. Second, at the firm level, this study carried out a comparative analysis focusing on recent global market trends and successful startup cases related to the 4th industrial revolution such as artificial intelligence, robotics, blockchain, and fintech. Third, at the individual level, this study conducted a survey and Focus Group Interview (FGI) with researchers of Government-Funded Research Institutes (GRI) in science and engineering field about the entrepreneurship and startup perception. As a result, total 10 major policy alternatives are derived by main issues and implications from each level. Firstly, at the national level, the results shows the necessity in 1) shifting the policy strategy from ‘Startup Pull’ to ‘Entrepreneurship Push’, 2) establishing entrepreneurial lifelong education system, 3) building the environment for technological finance. Secondly, at the firm level, it derivatively suggests policy alternatives in 1) restructuring the entry regulations in the new industry sectors from ‘Positive Listings’ to ‘Comprehensive Negative Listings’, 2) spreading entrepreneurship and startup culture through improvement of the system for attracting high-quality human resources into the innovative startups and expansion of social safety nets, 3) promoting the global successful startups like unicorns through building the private-led virtuous circle ecosystem of investment and exit. Lastly, at the individual level, it proposes policies in 1) supporting legal and institutional guidelines for researchers’ startups, 2) expanding organizations for supporting technology commercialization and innovative startups, 3) systematizing programs for supporting entrepreneurs from GRI, and 4) constructing the private supporting ecosystem for the researchers who want to establish startups. The results from the unique multi-level research are expected to provide multi-purpose solutions to various fields such as policy makers, startups, and researchers.
IT 프로젝트 팀에 있어서 내외부 사회적 자본과 조직 분위기에 관한 연구
이정우(Jungwoo Lee),이혜정(Hyejung Lee),이슬기(Seulki Lee) 한국IT서비스학회 2017 한국IT서비스학회지 Vol.16 No.3
IT project teams are composed of experts from various domains with different backgrounds, such as business and technologies. Thus, enhancing knowledge sharing and increasing team social capital are critical for the success of the project. This study examines the relationship among the team social capital, team climate and team performance. A research model and hypotheses are developed from literature review and empirically validated. The research model consists of team social capital, team climate and team performance. Specifically, team social capital, as antecedents, wasconceptualized asinternal and external differentiated by team boundary, and team climate is conceptualized as innovative climate and supportive climate. Using measures adopted from previous studies, 166 data points were collected to test the research model and related hypotheses. PLS data analysis indicated that internal and external social capitalhave positive effect on innovative climate while internal social capital has a positive effect on supportive team climate. The innovative and supportive climate has significant effect on the team performance. Based on the results, we proposed several team management skills for IT project managers. Theoretical constributions are discussed at the end with limitations and further studies.
Lee, Jeongchan,Li, Meng,Kim, Jeyoung,Shin, Geonho,Lee, Ga-won,Oh, Jungwoo,Lee, Hi-Deok The Institute of Electronics and Information Engin 2017 Journal of semiconductor technology and science Vol.17 No.2
Recently, Ni-InGaAs has been required for high-performance III-V MOSFETs as a promising self-aligned material for doped source/drain region. As downscaling of device proceeds, reduction of contact resistance ($R_c$) between Ni-InGaAs and n-InGaAs has become a challenge for higher performance of MOSFETs. In this paper, we compared three types of sample, vacuum, 2% $H_2$ and 4% $H_2$ annealing condition in rapid thermal annealing (RTA) step, to verify the reduction of $R_c$ at Ni-InGaAs/n-InGaAs interface. Current-voltage (I-V) characteristic of metal-semiconductor contact indicated the lowest $R_c$ in 4% $H_2$ sample, that is, higher current for 4% $H_2$ sample than other samples. The result of this work could be useful for performance improvement of InGaAs n-MOSFETs.
Crystal properties of atomic-layer deposited beryllium oxide on crystal and amorphous substrates
Lee, Seung Min,Jang, Yoonseo,Yum, Jung Hwan,Larsen, Eric S,Lee, Woo Chul,Kim, Seong Keun,Bielawski, Christopher W,Oh, Jungwoo Institute of Physics 2019 Semiconductor science and technology Vol.34 No.11
<P>We present the crystal properties of beryllium oxide (BeO) films on Si (100), GaN (001), and amorphous SiO<SUB>2</SUB> substrates grown by atomic-layer deposition (ALD). Because of the strong bonding interactions intrinsic to beryllium, BeO thin films have been grown in crystalline phases regardless of the substrate type. Transmission electron microscopy revealed crystallized BeO films with small interfacial layers. The epitaxial relationships and domain-matching configurations were confirmed by crystal simulation. Using x-ray diffraction analyses, ALD BeO films with thicknesses of 50 nm showed wurtzite (002) crystal phases for all substrates studied. Raman spectroscopy confirmed that the crystallinity of the BeO film grown on GaN was superior to that on Si and SiO<SUB>2</SUB> substrates. Atomic force microscopy and water contact angle goniometry measurements indicated that the BeO film grown on GaN in a planar mode was due to its low film energy.</P>
Lee, Jungwoo,Park, Taehee,Lee, Jongtaek,Yi, Whikun American Scientific Publishers 2014 Journal of Nanoscience and Nanotechnology Vol.14 No.8
<P>We report characteristic field emission (FE) properties of single-walled carbon nanotubes (SWCNTs) synthesized inside the pores as well as on the top surface of a porous silicon (PS) substrate. Turn-on fields and emission current densities were measured and compared with those of other types of SWCNTs in similar environments. Investigation of the FE properties of SWCNTs synthesized inside the pores of a PS substrate revealed a low turn-on field of approximately 2.25 V/μm at 10 μA/cm2 and a high field-enhancement factor (6182) compared with other samples. A life-time stability test was performed by monitoring the current density before and after repeated exposure to O2, suggesting that the pore channel can effectively prevent O2(+) ion etching from destroying SWCNTs within the pores of the PS layer.</P>