• Title/Summary/Keyword: synthesis optimization

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Combinatorial Synthesis and Screening of the $Eu^{2+}$-activated Phosphors for LED in the System CaO-$Al_2O_3-SiO_2$

  • Park, Seung-Hyok;Yoon, Ho-Shin;Kim, Chang-Hae;Jang, Ho-Gyeom
    • 한국정보디스플레이학회:학술대회논문집
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    • 2004.08a
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    • pp.647-649
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    • 2004
  • We have synthesized phosphor in the system CaO-$Al_2O_3-SiO_2$ by combinatorial polymerized-complex method. The application of combinatorial synthesis and characterization of luminescent materials has been enlarged to identification and optimization in interesting new phosphor. In this study, we investigated luminescent properties of above-mentioned materials by excitation and emission spectra. In $Eu^{2+}$ activated $Ca_1Al_2Si_2O_8$ phosphor emit the blue light.

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Synthesis of 2-Thio-4-aminopyrimidine Derivatives as Anti-cancer Agent

  • Lee, Sang-Hyo;Lee, Jin-Ho
    • Biomedical Science Letters
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    • v.15 no.2
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    • pp.105-112
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    • 2009
  • The screening of the anti-cancer activity of the chemical library provided 2-thio-4-aminopyrimidine as the initial hit. The confirmation of structure and biological effect of hit was performed by synthesis and biological evaluation. The optimization of hit was performed by derivatization of substituents while keeping the core structure. The evaluation of growth inhibitory activity was carried out using SRB assay against 6 human cancer cell lines and human fibroblast. The growth inhibitory activity of compounds showed substituent dependency and more than 5 compounds showed complete growth inhibition of cancer cell lines at 10 ${\mu}M$ concentration. Chemical library screening followed by synthetic modification provided possibility that 2-thio-4-aminopyrimidine can be used as a new scaffold for the development of anti-cancer agent.

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An Optimization of Speech Database in Corpus-based speech synthesis sytstem (코퍼스기반 음성합성기의 데이터베이스 최적화 방안)

  • Jang Kyung-Ae;Chung Min-Hwa
    • Proceedings of the KSPS conference
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    • 2002.11a
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    • pp.209-213
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    • 2002
  • This paper describes the reduction of DB without degradation of speech quality in Corpus-based Speech synthesizer of Korean language. In this paper, it is proposed that the frequency of every unit in reduced DB should reflect the frequency of units in Korean language. So, the target population of every unit is set to be proportional to their frequency in Korean large corpus(780K sentences, 45Mega phonemes). Second, the frequent instances during synthesis should be also maintained in reduced DB. To the last, it is proposed that frequency of every instance should be reflected in clustering criterion and used as criterion for selection of representative instances. The evaluation result with proposed methods reveals better quality than using conventional methods.

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A New Method for Synthesis of Line Source Array Antennas with Difference Patterns (차패턴을 갖는 선전원 배열 안테나 합성을 위한 새로운 방법)

  • Song, Chang-Hyun;Jun, Sang-Jae;Park, Eui-Joon
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • 2005.11a
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    • pp.357-360
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    • 2005
  • In the synthesis of the continuously distributed line source antennas with arbitrary patterns, the formulas of Taylor sum pattern and Bayliss difference pattern have been mainly used. In this paper, an optimization scheme is newly presented to directly synthesize the desired difference patterns from Taylor line source formula, and then the distributions are numerically adapted to the specified difference patterns by using an appropriate iterative sampling method.

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A Design of Mutirate Filter flanks using Un Control Approach ($H_\infty$ 제어기법을 적응한 다중비 필터 뱅크의 설계)

  • 이상철;박종우;박계원
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.5 no.6
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    • pp.1089-1093
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    • 2001
  • A H$\infty$ control theory is applied to the design problem of synthesis filters in a mutirate filter bank. We select a desired pure time-delay system as reference model, and then consider the error system between the mutirate filter bank and the reference model. 1'he synthesis filters minimize the ι$_2$-induced norm of the error system.

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Thermal Chemical Vapor Deposition of Graphene Layers

  • Kwon, Kyoeng-Woo;Do, Woo-Ri;Hwang, Jinha
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.02a
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    • pp.644-644
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    • 2013
  • Graphene is a two-dimensional sp2 layer material. Despite the short history in the empirical synthesis of the graphene layers, the academic/industrial unique features have brought highly significant interest in research and development related to graphene-related materials. In particular, the electrical and optical performances have been targeted towards pre-existing microelectronicand emerging nanoelectronic applications. The graphene synthesis relies on a variety of processing factors, such as temperature, pressure, and gas ratios involving H2, CH4, and Ar, in addition to the inherent selection of copper substrates. The current work places its emphasis on the role of experimental factors in growing graphene thin films. The thermally-grown graphene layers are characterized using physical/chemical analyses, i.e., four point resistance measurements, Raman spectroscopy, and UV-Visible spectrophotometry. Ultimately, an optimization strategy is proposed in growing high-quality graphene layers well-controlled through empirical factors.

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Optimization of Expression Conditions Enhances Production of Sepiapterin, a Precursor for Tetrahydrobiopterin Biosynthesis, in Recombinant Escherichia coli

  • Park, Eun-Hee;Lee, Won-Heong;Jang, Mi-Hee;Kim, Myoung-Dong
    • Journal of Microbiology and Biotechnology
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    • v.25 no.10
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    • pp.1709-1713
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    • 2015
  • Sepiapterin is a precursor for the synthesis of tetrahydrobiopterin (BH4), which is a wellknown cofactor for aromatic amino acid hydroxylation and nitric oxide synthesis in higher mammals. In this study, a recombinant Escherichia coli BL21(DE3) strain harboring cyanobacterial guanosine 5’-triphosphate cyclohydrolase 1 (GCH1) and human 6-pyruvoyltetrahydropterin synthase (PTPS) genes was constructed to produce sepiapterin. The optimum conditions for T7 promoter–driven expression of GCH1 and PTPS were 30℃ and 0.1 mM isopropyl-β-D-thioglucopyranoside (IPTG). The maximum sepiapterin concentration of 88.1 ± 2.4 mg/l was obtained in a batch cultivation of the recombinant E. coli, corresponding to an 18-fold increase in sepiapterin production compared with the control condition (37℃ and 1 mM IPTG).

Design of $H_2$ and $H_{\infty}$ static output feedback controllers (정적출력궤환 $H_2$$H_{\infty}$ 제어기 설계)

  • Kim, Seog-Joo;Lee, Jong-Moo;Cheon, Jong-Min;Kwon, Soon-Man;Park, Min-Kook
    • Proceedings of the KIEE Conference
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    • 2005.07d
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    • pp.2564-2566
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    • 2005
  • This paper presents an iterative linear matrix inequality (LMI) method for $H_2$ and $H_{\infty}$ optimal static output feedback (SOF) control, which is expressed in terms of LMIs subject to an additional rank condition. We propose a linear Penalty function to penalize the rank constraint so that static $H_2$ and $H_{\infty}$ synthesis results in solving a series of convex LMI optimization problems. Numerical experiments for various $H_2$ and $H_{\infty}$ SOF synthesis were performed to demonstrate the effectiveness of the proposed algorithm.

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$H_\infty$ control of contact position and force of a manipulator

  • Lee, Sangmoo;Yae, Harold
    • 제어로봇시스템학회:학술대회논문집
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    • 1994.10a
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    • pp.440-445
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    • 1994
  • An application of H$_{\infty}$ synthesis to contact control of a manipulator is suggested. Based on computed torque linearization of a manipulator, a target dynamics for contact motion control is defined and used as a reference model. The target dynamics relates position and force errors through free motion impedance and force error compensators. The H$_{\infty}$ control synthesis is adopted to find an optimum the compensator for position tied force control in various directions of the end-effector. The optimization is performed on the augmented criteria, which trades off the sensitivity function of the errors and the input load at the joints. A design example of the compensator is provided that meets the design specifications.s.

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Colouring Effect of Malayaite Formation and Synthesis Sphene-Pink Pigment (Sphene-Pink 안료합성 및 Malayaite 결정이 발색에 미치는 영향)

  • Lee, Hyun-Soo;Lee, Byung-Ha
    • Journal of the Korean Ceramic Society
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    • v.45 no.3
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    • pp.172-178
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    • 2008
  • This paper described the study of a sphene-pink pigment based on $Cr_2O_3-SnO_2-CaO-SiO_2$ system exhibits stable pink-red color at high temperature. This study is focused on the optimization of the synthesis parameter such as temperature and holding time for the formation the Malayaite crystal. Malayaite crystal is sensitively influenced by the synthesizing temperature, maintaining time and contents of substituting chromium. The crystal phases formed at different temperatures exhibits various color. The optimum temperature is suggested at $1300^{\circ}C$ for 2 h and substituting contents of Cr for Sn is 0.01 mole. The maximum substituting contents is 0.02 mole based on analysis results by XRD, FT-IR, SEM and UV-vis.