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Thermally Induced Mesophase Development in Ethanesilica Films via Macromolecular Templating Approach

  • Cho, Whirang;Char, Kook-Heon;Kwon, Su-Yong
    • Macromolecular Research
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    • v.17 no.9
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    • pp.697-702
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    • 2009
  • Mesoporous ethanesilica thin film was prepared using PEO-PLGA-PEO triblock copolymers as structure-directing agents and (1,2-bis(triethoxysilyl) ethane BTESE; bridged organosilicates) as inorganic precursors via one-step sol-gel condensation of ethanesilica precursors. The mesostructure of ethanesilica films is critically dependent on the processing experimental parameters after the hydrolyzed silica sol mixture was spin-cast. This study examined the effects of the block copolymer template/organosilica precursor ratio in the casting solution and aging period before calcination of the mesostructure. It was further demonstrated that mesoscopic ordering of organosilicate thin films is induced by the rearrangement of block copolymer template/organosilica hybrid during thermal decomposition of the PEO-PLGA-PEO triblock copolymer. The mesoporous structure and morphology were characterized by SAXS, TEM and solid-state NMR measurement.

Study of Photonic Crystal Waveguide in Microwave Regime Using 3D FDTD Simulation (3차원 FDTD모사를 이용한 마이크로웨이브 영역에서의 광결정 도파로에 관한 연구)

  • Han, Seung-Ho;Park, Q-Han;Roh, Young-Geun;Heonsu leon
    • Proceedings of the Optical Society of Korea Conference
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    • 2003.02a
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    • pp.184-185
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    • 2003
  • Unlike the conventional waveguide such as optical fiber using total internal reflection, photonic crystal waveguide(PCW), a waveguide made of a line defect in a photonic crystal(PC) structure, does not admit an analytic approach due to its complexity but requires a direct numerical approach. Here, we present numerical results of computer simulation for PCW by using the three-dimensional(3D) Finite-Difference Time -Domain(FDTD) algorithm. (omitted)

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Host effects on electrical conductivity of $ReO_3$ doped organic semiconductors

  • Lee, Jae-Hyun;Leem, Dong-Seok;Kim, Jang-Joo
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.346-349
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    • 2009
  • We investigated the doping effects of $ReO_3$ in different p-type organic semiconductors on the formation of charge transfer complexes and the electrical conductivity by comparing the absorption in ultraviolet-visible-nearinfrared (UV-Vis-NIR) and the current density-voltage characteristics of the hole only devices, respectively. The large energy difference between the HOMO level of host and Fermi energy level of dopant (${\Delta}E$=$E_{HOHO,host}$ - $E_{F,dopant}$) gives higher concentration of CT complexes and enhanced conductivity.

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Curing Reaction of Urea-formaldehyde Resin Using Real Time FT-IR Spectroscopy (실시간 FT-IR 분광분석법을 이용한 우레아-포름알데히드 수지의 경화반응)

  • Lee, Young-Kyu;Kim, Hyun-Joong
    • Journal of Adhesion and Interface
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    • v.13 no.2
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    • pp.85-88
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    • 2012
  • In this paper, the curing reaction of UF resins was investigated by a real time FT-IR method. The curing temperature range of the UF resin was $25{\sim}200^{\circ}C$. It was found that the reactions of UF resin at different temperatures resultedin resins with different cross-linked structures. A real time FT-IR spectroscopy can be considered as a good routine analytical tool for following the progress of UF resin curing.

Searching for Electromagnetic Counterpart of Gravitational Wave Source with KMTNet

  • Kim, Joonho;Im, Myungshin;Lee, Chung-Uk;Kim, Seung-Lee
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.62.3-62.3
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    • 2019
  • After first identification of electromagnetic counterpart of gravitational wave source (GW170817), era of multi-messenger astronomy has begun. For specifying coordinate, magnitude, and host galaxy information, optical follow-up observation of GW source becomes important. With following engineering run and O3 run of LIGO and VIRGO starting in March 2019, we present searching strategy for optical counterpart of GW source using KMTNet. 24 hours monitoring system and large field of view (4 square-degree) of KMTNet are advantage to discover a transient like GW event. By performing tiling observation of high probability area in GW localization map, we expect to observe early light-curve of GW optical counterpart. After identification, follow-up observation with various KMTNet bands and other telescopes like Gemini and UKIRT will also be performed. We will study collision mechanism, progenitor, and characteristics of host galaxy using observation data of GW source.

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Real-Time Reduction Software for Slitless Spectral Image

  • Ji, Tae-Geun;Pak, Soojong;Shin, Suhyun;Byeon, Seoyeon;Im, Myungshin
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.71.3-71.3
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    • 2019
  • For slitless spectroscopy, we have installed the Volume Phase Holographic (VPH) gratings in the filter wheel of the SQUEAN on the 2.1m telescope at McDonald Observatory in Texas, United States. This system can effectively take spectra and monitor the variabilities of many sources, such as quasi-stellar objects, supernovae, and active galactic nuclei. On the single image frame, there are many spectra of the point sources. Therefore, a target extraction needs to trace along the tilted dispersion and to minimize the confusions by other sources. We present a real-time reduction software that has the functions with spectra extraction and wavelength calibration.

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The Mechanism of Gold Deposition by Thermal Evaporation

  • Mark C. Barnes;Kim, Doh-Y.;Nong M. Hwang
    • Proceedings of the Korea Association of Crystal Growth Conference
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    • 2000.06a
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    • pp.127-142
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    • 2000
  • The charged cluster model states that chemical vapor deposition (CVD) begins with gas phase nucleation of charged clusters followed by cluster deposition on a substrate surface to form a thin film. A two-chambered CVD system, separated by a 1-mm orifice, was used to study gold deposition by thermal evaporation in order to determine if the CCM applies in this case. At a filament temperature of 1523 and 1773 K, the presence of nano-meter sized gold clusters was found to be positive and the cluster size and size distribution increased with increasing temperature. Small clusters were found to be amorphous and they combined with clusters already deposited on a substrate surface to form larger amorphous clusters on the surface. This work revealed that gold thin films deposited on a mica surface are the result of the sticking of 4-10 nm clusters. The topography of these films was similar to those reported previously under similar conditions.

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The Effects of Heat Input and Gas Flow Rate on Weld Integrity for Sleeve Repair Welding of In-Service Gas Pipelines

  • Kim, Y.P.;Kim, W.S.;Bang, I.W.;Oh, K.H.
    • International Journal of Korean Welding Society
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    • v.2 no.2
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    • pp.36-41
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    • 2002
  • The experimental and numerical study has been conducted on the sleeve repair welding of API 5L X65 pipeline. SMAW and GTAW were applied to weld the sleeve. The macrostructure and hardness of repair welds have been examined. The finite element analysis of the multi-pass sleeve-fillet welding has been conducted to validate the experiment and investigate the effects of in-service welding conditions. The effect of gas flow rate on the hydrogen cracking was investigated. The effect of internal pressure on residual stresses and plastic strain was investigated. The allowable heat input was predicted considering the maximum temperature of inner surface of pipe and cooling rate at CGHAZ.

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A Suggestion for the Strategic Choice of Seoul to be a Network Center in Northeast Asia

  • Ahn, Kun-Hyuck;Ohn, Yeong-Te
    • Journal of the Korean Regional Science Association
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    • v.15 no.2
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    • pp.155-187
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    • 1999
  • The East Asian Region has experienced remarkable economic growth and transformation of interurban networking over the past three decades, and urban competiti veness for a networking hub in this region has become a critical issue confronting cities. Competitiveness of the Seoul capital region for a networking hub in Northeast Asia is outstripped by other competing cities in East Asia, notwithstanding its geo-politically and geo-economically advantageous location in this region. In this paper, we aim to appraise the Seoul capital region's competitiveness in terms of logistics distribution, financial function and logistics distribution, financial function and agglomeration of transnational corporations (especially of RHOs and other managerial functions), and to advance the networking strategies of the region for a Northeast Asia hyb. As a result of analysis, we suggest that the Seoul capital region be developed as a Northeast Asian center for regional headquarters or leading global corporations and financial services for being a strategic nodal point in Northeast Asia in the 21st century. A recent survey shows that where to locate an RHQ is influenced by various factors, such as potential market and manufacturing site in the city's hinterland, quality of life, such things as culture, health, safety, education, a well-educated, English-speaking population, reliable air transport, state-of-the-art communications, and an active policy to offer foreign companies generous incentives. The Seoul capital region, which is located at a strategic nodal point advantageous as a springboard for its Northeast Asian hinterland, cannot meet the other conditions mentioned above. To overcome these drawbacks in attracting transnational capital and to create competitiveness as a strategic hub of RHQs in Northeast Asia, it is urgent to initiate a structural reform of the Korean economy, politics, and overall society, to minimize the regulation of FDI, and to provide various incentives for foreign investment. Moreover, we propose the construction of an 'International Business Town' in the Seoul capital region, as a medium to intermediate these strategies and to shape them in a spatial scale. The projected 'International Business Town(IBT)' will be a 'free city' open to international business in which liberal economic activities are guaranteed by special legislation and administration, infrastructures needed for international and improved accessibility to the airport are furnished, and the preference of foreign high-income investors for cultural and living environment are satisfactorily met. IBT is conspicuously differentiated from a raft of other cities' incentives in that it combines deregulation and incentive programs to attract the investment of transnational capital, with a spatial program of offering an urban environment preferred by the high-income investors for cultural and living environment are satisfactorily met. IBT is conspicuously differentiated from a raft of other cities' incentives in that it combines deregulation and incentive programs to attract the investment of transnational capita, with a spatial program of offering an urban environment preferred by the high-income and managerial class. Furthermore, it can be an excellent way of overcoming the xenophobia that has spread among the Korean population by concentrating foreign businesses and their lifestyles in a specific foreign businesses and their lifestyles in a specific zone. In conclusion, 'International Business Town', in line with other legislative and administrative incentive programs, will function as a driving force to make the Seoul capital regional more competitive as a regional business hub in Northeast Asia.

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