http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Kim, Sungnam,Jeon, Gumhye,Heo, Sung Woo,Kim, Hye Jeong,Kim, Seung Bin,Chang, Taihyun,Kim, Jin Kon The Royal Society of Chemistry 2013 Soft matter Vol.9 No.23
<P>We report a novel, yet simple, method for the preparation of high aspect ratio cylindrical microdomains oriented vertically on a substrate by using block copolymer micelles and temperature-programmed solvent vapor annealing. Multilayered spherical micelles were first prepared by spin-coating of polystyrene-<I>block</I>-poly(4-vinylpyridine) copolymer (PS-<I>b</I>-P4VP) in toluene solution on a silicon wafer. When temperature-programmed solvent vapor annealing was performed, the spherical micelle cores consisting of P4VP chains were transformed into vertically oriented cylindrical microdomains spanning the entire film thickness up to 550 nm corresponding to the aspect ratio of 15.2. Since nitrogen in the P4VP block could be easily coordinated with many metal precursors, we also fabricated a high density array of gold nanoparticle/polymer nanocomposite nanorods oriented vertically on the substrate.</P> <P>Graphic Abstract</P><P>High aspect ratio cylindrical microdomains oriented vertically on a substrate were prepared using block copolymer micelles and temperature-ramp solvent vapor annealing. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3sm27734h'> </P>
Kim, Beom Joon,Lee, Hyo-Sang,Lee, Joong Seok,Cho, Sanghyeok,Kim, Hyunjung,Son, Hae Jung,Kim, Honggon,Ko, Min Jae,Park, Sungnam,Kang, Moon Sung,Oh, Se Young,Kim, BongSoo,Cho, Jeong Ho American Chemical Society 2013 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.117 No.22
<P>We characterized the electrical properties of ambipolar polymer field-effect transistors (PFETs) based on the low-band-gap polymer, pNAPDO-DPP-EH. The polymer consisted of electron-rich 2,6-di(thienyl)naphthalene units with decyloxy chains (NAPDO) and electron-deficient diketopyrrolopyrrole units with 2-ethylhexyl chains (DPP-EH). The as-spun pNAPDO-DPP-EH PFET device exhibited ambipolar transport properties with a hole mobility of 3.64 × 10<SUP>–3</SUP> cm<SUP>2</SUP>/(V s) and an electron mobility of 0.37 × 10<SUP>–3</SUP> cm<SUP>2</SUP>/(V s). Thermal annealing of the polymer film resulted in a dramatic increase in the carrier mobility. Annealing at 200 °C yielded hole and electron mobilities of 0.078 and 0.002 cm<SUP>2</SUP>/(V s), respectively. The mechanism by which the mobility had improved was investigated via grazing incidence X-ray diffraction studies, atomic force microscopy, and temperature-dependent transport measurements. These results indicated that thermal annealing improved the polymer film crystallinity and promoted the formation of a longer-range lamellar structure that lowered the thermal activation energy for charge hopping. Thermal annealing, moreover, reduced charge trapping in the films and thus improved the electrical stability of the PFET device. This work underscores the fact that long-range ordering in a crystalline polymer is of great importance for efficient charge transport and high electrical stability.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2013/jpccck.2013.117.issue-22/jp400664r/production/images/medium/jp-2013-00664r_0010.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp400664r'>ACS Electronic Supporting Info</A></P>
Synthesis of Monoclinic Potassium Niobate Nanowires That Are Stable at Room Temperature
Kim, Seungwook,Lee, Ju-Hyuck,Lee, Jaeyeon,Kim, Sang-Woo,Kim, Myung Hwa,Park, Sungnam,Chung, Haegeun,Kim, Yong-Il,Kim, Woong American Chemical Society 2013 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.135 No.1
<P>We report the synthesis of KNbO<SUB>3</SUB> nanowires (NWs) with a monoclinic phase, a phase not observed in bulk KNbO<SUB>3</SUB> materials. The monoclinic NWs can be synthesized via a hydrothermal method using metallic Nb as a precursor. The NWs are metastable, and thermal treatment at ∼450 °C changed the monoclinic phase into the orthorhombic phase, which is the most stable phase of KNbO<SUB>3</SUB> at room temperature. Furthermore, we fabricated energy-harvesting nanogenerators by vertically aligning the NWs on SrTiO<SUB>3</SUB> substrates. The monoclinic NWs showed significantly better energy conversion characteristics than orthorhombic NWs. Moreover, the frequency-doubling efficiency of the monoclinic NWs was ∼3 times higher than that of orthorhombic NWs. This work may contribute to the synthesis of materials with new crystalline structures and hence improve the properties of the materials for various applications.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2013/jacsat.2013.135.issue-1/ja308209m/production/images/medium/ja-2012-08209m_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja308209m'>ACS Electronic Supporting Info</A></P>
Moon, Heejo,Jung, Yuna,Kim, Youngseo,Kim, Byeong Wook,Choi, Jin Gyu,Kim, Na Hee,Oh, Myung Sook,Park, Sungnam,Kim, B. Moon,Kim, Dokyoung American Chemical Society 2019 ORGANIC LETTERS Vol.21 No.11
<P>A new donor (D)-acceptor (A) type naphthalene-based oxazepine-containing fluorophore, <B>OXN-1</B>, is reported, which shows unusually high stability in various environments. Its photophysical properties and structural stabilities under harsh conditions are thoroughly examined. The high stability of <B>OXN-1</B> is explained by quantum chemical calculations. Its exceptional bioimaging capabilities for cells with low cytotoxicity are verified. In addition, its deep tissue imaging ability with two-photon microscopy (TPM) is evaluated.</P> [FIG OMISSION]</BR>
Kim, Soojin,Lee, Songyi,Anjong, Tikum Florence,Jang, Ha Yoon,Kim, Ji-Yeong,Lee, Chiho,Park, Sungnam,Lee, Hye Jin,Yoon, Juyoung,Kim, Jinheung American Chemical Society 2016 The Journal of Physical Chemistry Part C Vol.120 No.50
<P>For the practical use of a photobioreactor for artificial photosynthesis, efficient visible light-absorbing materials have to link reduction and oxidation catalysts for an efficient energy flow. As a step toward this goal of an NADH regeneration system and enzymatic production of solar fuels from CO2, we report the synthesis of a new polydiacetylene compound that is covalently connected with [Ru(phen-NH2) (bpy)(2)](2+) (bpy =2,2'-bipyridine, phen =1,10-phenonthroline-5-amine). The [(bpy)(2)Ru(phen-NH-)]-polydiacetylene absorbed a wide range of visible light because of the presence of two chromophores, the Ru complex and polydiacetylene. The polyacetylene backbone was converted from blue to red by conformational changes under the catalytic reaction conditions in a buffer solution. The electron transfer from the photoexcited [ku(phen)(bpy)(2)](2+) to the polydiacetylene backbone was observed. In a visible light-driven photocatalytic NAD+ reduction by (cyclopentadienyl)Rh(bpy)(H2O)(2+) With [(bpy),Ru(phen-NH)]-polydiacetylene, NADH was regenerated, and the reactivity using Ru(bpy),(phen-NH)-polydiacetyleue was enhanced relative to control experiments using only [Ru(phen)(bpy)(2)](2+) or polydiacetylene. The consecutive carbon dioxide reduction coupled with formate dehydrogenase was carried out to utilize the in situ photoregenerated NADH catalytically. The catalytic condition using [(bpy),Ru(phen-NH)]-polydiacetylene also showed much higher reactivity than the controls.</P>
Kim, Seungwook,Kim, Min-Seop,Lee, Chiho,Park, Sungnam,Cho, Won Il,Kim, Woong Elsevier 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.709 No.-
<P><B>Abstract</B></P> <P>Fundamentals in materials science are often based on understanding the relationships between the structures and properties of materials. Recently, our group reported on potassium niobate (KNbO<SUB>3</SUB>) nanowires with a metastable monoclinic phase that has never been observed before in bulk materials. In this paper, we report on the unique phase transition behaviors of these monoclinic nanowires and describe how their nonlinear optical properties are correlated with structural changes. The metastable monoclinic nanowires exhibit phase transition behaviors that are distinct from those of thermodynamically stable orthorhombic nanowires. The monoclinic nanowires undergo two phase transitions: monoclinic to tetragonal at 120 °C and tetragonal to cubic at 380 °C. In contrast, orthorhombic nanowires undergo phase transitions from orthorhombic to tetragonal and from tetragonal to cubic at 130 °C and 330 °C, respectively. The monoclinic and orthorhombic nanowires were found to exhibit clearly distinguishable variations in the second harmonic generation (SHG) intensity with variations in temperature. We show that the tetragonal structures derived from the monoclinic and orthorhombic phases are clearly different. The tetragonal phase derived from the monoclinic phase has higher spontaneous polarization and exhibits higher SHG intensity than the other tetragonal phase. Our analysis can be extended to explain the size-dependent properties of KNbO<SUB>3</SUB>. We calculated the spontaneous polarizations of the various phases based on the structural data and show how to use them to explain the above-mentioned structure–property relationships. The results of this study have important implications for both fundamental understanding and technological applications of metastable nanomaterials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Metastable monoclinic KNbO<SUB>3</SUB> nanowires exhibit unique phase transition behaviors. </LI> <LI> Tetragonal phases derived from monoclinic and orthorhombic phases are different. </LI> <LI> Intensity of second harmonic generation is strongly correlated to structural change. </LI> <LI> Spontaneous polarization explains the structure-dependent optical properties. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Influence of Thermal Annealing on the Microstructural Properties of Indium Tin Oxide Nanoparticles
Sungnam Kim,Seung Bin Kim,Hyun Chul Choi 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.1
In this work, we studied the microstructural changes of ITO during the annealing process. ITO nanoparticles were prepared by the sol-gel method using indium tin hydroxide as the precursor. The prepared sample was investigated using TEM, powder XRD, XPS, DRIFT, and 2D correlation analysis. The O 1s XPS spectra suggested that the microstructural changes during the annealing process are closely correlated with the oxygen sites of the ITO nanoparticles. The temperature-dependent in situ DRIFT spectra suggested that In-OH in the terminal sites is firstly decomposed and, then, Sn-O-Sn is produced in the ITO nanoparticles during the thermal annealing process. Based on the 2D correlation analysis, we deduced the following sequence of events: 1483(due to In-OH bending mode) → 2268, 2164 (due to In-OH stretching mode) → 1546 (due to overtones of Sn-O-Sn modes) → 1412 (due to overtones of Sn-O-Sn modes) cm−1.
무베어링 로터 훨타워 시험을 위한 무힌지 블레이드 강성보강에 따른 동특성 연구
김태주(Kim, Taejoo),윤철용(Yun, Chulyong),기영중(Kee, Youngjoong),김승호(Kim, Seung-Ho),정성남(Jung, Sungnam) 한국소음진동공학회 2013 한국소음진동공학회 논문집 Vol.23 No.2
Whirl tower test is conducted basically during helicopter rotor system development process. And for whirl tower test of rotor hub system, new design blade or existing blade which is remodeled for new rotor hub system is used. Because of simple shape and efficient aerodynamic characteristic, BO-105 helicopter blade is used for helicopter rotor hub development project widely. Originally BO-105 blade is used for hingeless hub system and blade root is used to flexure. So flap stiffness and lag stiffness at blade root area is relatively low compare with airfoil area. So, in order to apply the BO-105 blade to bearingless hub, blade root area have to be reinforced. And in this process, blade root area's section property is changed. In this paper, we suggest reinforcement method of BO-105 blade root area and study dynamic characteristic of bearingless rotor system with reinforcement BO-105 blade.