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김하양(Hayang Kim),김민정(Minjung Kim),김경애(Kyungae Kim),김진태(Jintae Kim),이승준(Seungjun Lee) 한국방송·미디어공학회 2004 한국방송공학회 학술발표대회 논문집 Vol.2004 No.-
Wireless sensor network을 위한 MAC(Medium Access Control) layer를 low-rate WPAN을 목적으로 한 IEEE 802.15.4 사양에 따라 구현하고 검증하였다. 센서 네트워크의 노드는 배터리로 동작하므로 에너지 소모가 가장 큰 걸림돌이 된다. power saving을 위한 몇 가지 방법을 포함한 IEEE 802.15.4 MAC protocol을 구현함으로써 wireless sensor network에 적용 가능함을 보였다.
Lee, Inhye,Kim, Kuglae,Lee, Sumin,Lee, Seungjun,Hwang, Eunjin,Shin, Kihye,Kim, Dayoung,Choi, Jungki,Choi, Hyunmo,Cha, Jeong Seok,Kim, Hoyoung,Lee, Rin-A,Jeong, Suyeong,Kim, Jeongsik,Kim, Yumi,Nam, Hon Oxford University Press 2018 Journal of experimental botany Vol.69 No.15
<▼1><P>A missense mutation of <I>KARRIKIN-INSENSITIVE2</I>, <I>KAI2</I><SUP><I>ply2</I></SUP>, compromises its ligand-binding activity, which subsequently impairs KAI2-signaling and multiple aspects of light-dependent responses.</P></▼1><▼2><P><B>Abstract</B></P><P>A smoke-derived compound, karrikin (KAR), and an endogenous but as yet unidentified KARRIKIN INSENSITIVE2 (KAI2) ligand (KL) have been identified as chemical cues in higher plants that impact on multiple aspects of growth and development. Genetic screening of light-signaling mutants in <I>Arabidopsis thaliana</I> has identified a mutant designated as <I>ply2</I> (<I>pleiotropic long hypocotyl2</I>) that has pleiotropic light-response defects. In this study, we used positional cloning to identify the molecular lesion of <I>ply2</I> as a missense mutation of <I>KAI2</I>/<I>HYPOSENSITIVE TO LIGHT</I>, which causes a single amino acid substitution, Ala219Val. Physiological analysis and genetic epistasis analysis with the KL-signaling components <I>MORE AXILLARY GROWTH2</I> (<I>MAX2</I>) and <I>SUPPRESSOR OF MAX2 1</I> suggested that the pleiotropic phenotypes of the <I>ply2</I> mutant can be ascribed to a defect in KL-signaling. Molecular and biochemical analyses revealed that the mutant KAI2<SUP>ply2</SUP> protein is impaired in its ligand-binding activity. In support of this conclusion, X-ray crystallography studies suggested that the <I>KAI2</I><SUP><I>ply2</I></SUP> mutation not only results in a narrowed entrance gate for the ligand but also alters the structural flexibility of the helical lid domains. We discuss the structural implications of the Ala219 residue with regard to ligand-specific binding and signaling of KAI2, together with potential functions of KL-signaling in the context of the light-regulatory network in <I>Arabidopsis thaliana</I>.</P></▼2>
Kim, So-Yoen,Kim, Jin-Hyoung,Son, Mi Rang,Yi, Seungjun,Kim, Chul Hoon,Son, Ho-Jin,Kang, Sang Ook American Chemical Society 2019 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.123 No.31
<P>In this study, we prepared phenylimidazole-based C^N-cyclometalated Ir(III) complexes (<B>DMP</B>, <B>TPF2</B>) and a C^C-cyclometalated Ir(III) complex (<B>PMP</B>), and investigated the energy transfer process by examining the intermolecular interactions between the two cyclometalated Ir(III) complexes. In films doped with 3% Ir(C^C)<SUB>3</SUB> complex (<B>PMP</B>) and 15% Ir(C^N)<SUB>3</SUB> complex (<B>DMP</B> or <B>TPF2</B>), the <B>PMP</B> effectively induced energy transfer to the <B>DMP</B> or <B>TPF2</B>. This intermolecular energy transfer process was investigated using a picosecond time-resolved emission spectroscopic method. In the case of mixing <B>PMP</B> with <B>DMP</B>, where two types of luminescence were observed at 470 and 580 nm, the emission at 470 nm was due to <B>DMP</B>, while the emission at 580 nm can be assigned as the intermolecular exciplex emission. By contrast, in the case of mixing <B>PMP</B> with <B>TPF2</B>, the emission at 465 nm corresponding to the <B>PMP</B> emission region decreased for 18.5 ns, while the emission at 530 nm corresponding to <B>TPF2</B> increased. This emission can be attributed to the energy transfer from <B>PMP</B> to <B>TPF2</B>. In addition, no change was observed in the longer wavelength region than the <B>TPF2</B> emission region for 10 μs. We analyzed the energy transfer process when <B>PMP</B> was added to the dopant (<B>DMP</B> and <B>TPF2</B>) and found that <B>TPF2</B> was more efficient than <B>DMP</B> in the device without <B>PMP</B> doping, but it showed performance deterioration in high current density (>1 mA/cm<SUP>2</SUP>) owing to activation of fluorinated ligands. Finally, it was confirmed that the operation lifetime and efficiency of the device were improved by doping 3% of <B>PMP</B> in emissive layer (EML).</P> [FIG OMISSION]</BR>
Ultimate Behavior of Steel Cable-Stayed Bridges During Construction
Seungjun Kim,원덕희,강영종 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.3
This paper presents an investigation of the ultimate behavior of steel cable-stayed bridges under construction. In general, cable-stayed bridges are subjected to quite large compressive forces induced by stayed cables, and may become unstable due to these excessive compressive forces, especially while under construction because of the characteristics of the general construction method. To investigate the ultimate behavior of steel cable-stayed bridges under construction, a three-step analysis, consisting of initial shape analysis, construction stage analysis and external load analysis, is proposed and used with considering various geometric and material nonlinearities of the structure, such as the cable-sag eff ect, beam-column eff ect of the girder and mast, large displacement eff ect and gradual yield eff ect. By performing extensive analytical study, the general ultimate behavior and mode are found and described in detail. Also, the eff ects of various geometric parameters on the ultimate behavior and load carrying capacity are studied, such as the cable-arrangement types, girder-mast fl exural stiff ness ratio and sectional area of stay cables.
Structural behavior of cable-stayed bridges after cable failure
Seungjun Kim,Young Jong Kang 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.59 No.6
This paper investigates the change of structural characteristics of steel cable-stayed bridges after cable failure. Cables, considered as the intermediate supports of cable-stayed bridges, can break or fail for several reasons, such as fire, direct vehicle clash accident, extreme weather conditions, and fatigue of cable or anchorage. Also, the replacement of cables can cause temporary disconnection. Because of the structural characteristics with various geometric nonlinearities of cable-stayed bridges, cable failure may cause significant change to the structural state and ultimate behavior. Until now, the characteristics of structural behavior after cable failure have rarely been studied. In this study, rational cable failure analysis is suggested to trace the new equilibrium with structural configuration after the cable failure. Also, the sequence of ultimate analysis for the structure that suffers cable failure is suggested, to study the change of ultimate behavior and load carrying capacity under specific live load conditions. Using these analysis methods, the statical behavior after individual cable failure is studied based on the change of structural configuration, and distribution of internal forces. Also, the change of the ultimate behavior and load carrying capacity under specific live load conditions is investigated, using the proposed analysis method. According to the study, significant change of the statical behavior and ultimate capacity occurs although just one cable fails.
Effects of hinge design of horizontal-swing fast tool servo (HFTS) for micro-patterning on a roll
Kim, Miru,Lee, Deug Woo,Lee, Seungjun,Kim, Yongwoo,Jung, Yoongho Springer-Verlag 2018 INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TE Vol.95 No.1
<P>The fast tool servo (FTS) system is widely used for micro-structure manufacturing by diamond turning. Conventional FTS had been generally researched regarding the front/back-axial swing direction. However, development of more complex machining technology is demanded for the FTS. In this paper, we developed a right/left-horizontal swing FTS (HFTS) and analyzed its characteristics with various hinge structures. Flexure hinge structures were designed four types, considering the influence of mass and the number of hinges. Also, to compare the difference in machining performance with hinge structure, we compared the results of a machined microwave pattern on a Ni-coated steel roll mold. Comparing the machining results, the influence of mass was minor; however, machining performance varied with the number of fixed hinges. Having two fixed hinges was not suitable for precision machining due to strong over-constraint conditions. Thus, a single-hinge HFTS provides the appropriate hinge structure for precision machining of a roll mold.</P>
Kim, Jin-Hyoung,Kim, So-Yoen,Jang, Seol,Yi, Seungjun,Cho, Dae Won,Son, Ho-Jin,Kang, Sang Ook American Chemical Society 2019 Inorganic Chemistry Vol.58 No.23
<P>Incorporation of an electron-withdrawing −SO<SUB>2</SUB>CF<SUB>3</SUB> substituent to cyclometalating C^N-phenylpyridine (ppy) ligand resulted in an expected blue-shifted phosphorescence in the corresponding homoleptic <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>3</B></SUB> complex, showing the emission of λ<SUB>em</SUB> = 464 nm at 300 K. One of its heteroleptic derivatives, modified by a pyrazolyl borate LX ligand, <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>2</B></SUB><B>(bor)</B>, exhibited further blue-shifted phosphorescence of λ<SUB>em</SUB> = 460 nm at 300 K. Cyclic voltammograms (CVs) and density-functional theory (DFT) calculations supported the efficacy of the electron-withdrawing capability of the SO<SUB>2</SUB>CF<SUB>3</SUB> substituent lowering HOMO energy and obtained widened bandgaps and resumed blue emissions for all of the iridium complexes studied. The homoleptic complexes of both substituents, <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>3</B></SUB> and <B>Ir(ppySF)</B><SUB><B>3</B></SUB>, reached the higher quantum yields (<I>Φ</I><SUB>PL</SUB>) of (0.89 and 0.72), respectively. Similarly, emission quantum yields (<I>Φ</I><SUB>PL</SUB>) of the heteroleptic derivatives were reported to be (0.75, 0.83, and 0.87) for <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>2</B></SUB><B>(acac)</B>, <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>2</B></SUB><B>(bor)</B>, and <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>2</B></SUB><B>(pic)</B>, respectively. Emission kinetics support the enhanced quantum efficiency when <I>k</I><SUB>r</SUB> and <I>k</I><SUB>nr</SUB> values are compared between <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>3</B></SUB> and <B>Ir(ppySF)</B><SUB><B>3</B></SUB>, and both values favorably contribute to attaining a higher quantum efficiency for <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>3</B></SUB>. Among solution-processed multilayered devices having an ITO/PEDOT:PSS/TCTA:Ir dopant (10:1, <I>w</I>/<I>w</I>)/TmPyPB/Liq/Al structure, a heteroleptic dopant, <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>2</B></SUB><B>(bor)</B>, exhibited better device performance, reporting an external quantum efficiency (EQE) of 1.14%, current efficiency (CE) of 2.31 cd A<SUP>-1</SUP>, and power efficiency (PE) of 1.21 lm W<SUP>-1</SUP>, together with blue chromaticity of CIE<SUB>x,y</SUB> = (0.16, 0.32).</P><P>Blue phosphorescence of Ir(III) complexes can be tuned with the introducing of strong electron withdrawing substituents and the variation in the ancillary ligands.</P> [FIG OMISSION]</BR>