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Pyridinolysis of O-Aryl Phenylphosphonochloridothioates in Acetonitrile

  • Lumbiny, Bilkis Jahan;Adhikary, Keshab Kumar;Lee, Bon-Su;Lee, Hai-Whang
    • Bulletin of the Korean Chemical Society
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    • v.29 no.9
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    • pp.1769-1773
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    • 2008
  • fThe kinetics and mechanism of the reactions of Y-O-aryl phenylphosphonochloridothioates with X-pyridines are investigated in acetonitrile at 35.0 C. The negative value of the cross-interaction constant, ρXY = −0.46, indicates that the reaction proceeds by concerted SN2 mechanism. The observed kH/kD values involving d-5 pyridine (C5D5N) nucleophiles are greater than unity (1.05-1.11). The net primary deuterium kinetic isotope effects, (kH/kD)net = 1.28-1.35, excluding the increased pKa effect of d-5 pyridine are obtained. The transition state with a hydrogen bond between the leaving group Cl and the hydrogen (deuterium) atom in the C-H(D) is suggested for the studied reaction system.

A Study on the Piezoelectric Sounder Using the PMN-PT-PZ with Sr Sustitutions (Sr이 치환된 PMN-PT-PZ 계 세라믹스를 이용한 압전 발음체에 관한 연구)

  • You, H.S.;Paek, D.S.;Kang, J.K.;Park, C.Y.
    • Proceedings of the KIEE Conference
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    • 1991.11a
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    • pp.293-295
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    • 1991
  • In this study, we investigated the possibilty that Pb(Mg1/3Nb2/3)O3PbTiO3PbZrO3 ceramics with strontium substitutions could be used for piezoelectric sounders. Piezoelectric buzzer is one of them. By partially substituting Sr for Ph, dielectric constants had values greater than 2000, the value proper piezoelectric buzzer, piezoelectric constant(d31) had a maximum value, 298 [1012C/N], at the Sr 5 mol % substitution. Sound level of piezoelectric buzzer had the highest value of 91 dB at the Sr 5 mol % substitution.

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NEHARI MANIFOLD AND MULTIPLICITY RESULTS FOR A CLASS OF FRACTIONAL BOUNDARY VALUE PROBLEMS WITH p-LAPLACIAN

  • Ghanmi, Abdeljabbar;Zhang, Ziheng
    • Bulletin of the Korean Mathematical Society
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    • v.56 no.5
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    • pp.1297-1314
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    • 2019
  • In this work, we investigate the following fractional boundary value problems {tDαT(0Dαt(u(t))p20Dαtu(t))=W(t,u(t))+λg(t)u(t)q2u(t),t(0,T),u(0)=u(T)=0, where W(t,u) is the gradient of W(t, u) at u and $W{\in}C([0,T]{\times}{\mathbb{R}}^n,{\mathbb{R}})$ is homogeneous of degree r, λ is a positive parameter, $g{\in}C([0,T])$, 1 < r < p < q and ${\frac{1}{p}}<{\alpha}<1$. Using the Fibering map and Nehari manifold, for some positive constant λ0 such that $0<{\lambda}<{\lambda}_0$, we prove the existence of at least two non-trivial solutions

A Note on the Dependence Conditions for Stationary Normal Sequences

  • Choi, Hyemi
    • Communications for Statistical Applications and Methods
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    • v.22 no.6
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    • pp.647-653
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    • 2015
  • Extreme value theory concerns the distributional properties of the maximum of a random sample; subsequently, it has been significantly extended to stationary random sequences satisfying weak dependence restrictions. We focus on distributional mixing condition D(un) and the Berman condition based on covariance among weak dependence restrictions. The former is assumed for general stationary sequences and the latter for stationary normal processes; however, both imply the same distributional limit of the maximum of the normal process. In this paper D(un) condition is shown weaker than Berman's covariance condition. Examples are given where the Berman condition is satisfied but the distributional mixing is not.

H.P.L. Value in Abnormal Pregnancy by Hemagglutination-Inhibition Reaction (비정상임산부(非正常妊産婦)의 혈청중(血淸中) H.P.L.의 혈구응집조지반응(球凝集阻止反應)에 의한 측정(測定)에 관(關)한 연구(硏究))

  • Kim, Dong-Jin;Shin, Myon-Woo
    • Clinical and Experimental Reproductive Medicine
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    • v.4 no.1
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    • pp.27-32
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    • 1977
  • Serum levels of human placental lactogen were measured by hemagglutination inhibition reaction in 26 normal pregnant state and in patients with 16 toxemia and 6 F.D.I.U. beyond their thirtieth week of gestation to evaluate their clinical usefulness. It was realized that HPL-HAIR Test Kit was easy to use and produced reliable results. The general conclusion were as follows: 1) HPL value was 68ug/ml in normal pregnancy. 2) The levels in mild toxemia were similar in the normal state. 3) The levels in severe toxemia were similar or slightly lower than in the normal and mild toxemia. 4) The levels in F.D.I.U. were lower than in the normal state.

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Design and Implementation of the low power and high quality audio encoder/decoder for voice synthesis (음성 합성용 저전력 고음질 부호기/복호기 설계 및 구현)

  • Park, Nho-Kyung;Park, Sang-Bong;Heo, Jeong-Hwa
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.13 no.6
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    • pp.55-61
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    • 2013
  • In this paper, we describe design and implementation of audio encoder/decoder for voice synthesis. It uses the encoding of difference value of successive samples instead of the original sample value. and has the compression ratio of 4. The function is verified by using FPGA and the performance is measured by the fabricated chip using 0.35μm standard CMOS process. The system clock is 16.384MHz. The measured THD+n is from -40dB to -80dB with frequency variation and the power consumption is about 80mW. It is suited for the mobile application of high audio quality and low power consumption.

Machine Learning to Improve Tensile Strength of 3D-Printed Tensile Specimens (3D 프린팅된 인장 시편의 인장강도 향상을 위한 머신러닝)

  • Bum-Soo Kim;Seong-Yeol Han
    • Design & Manufacturing
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    • v.18 no.1
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    • pp.11-17
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    • 2024
  • As the range of 3D printed applications expands, there is an increasing demand for the production of outputs wit h excellent durability and reliability. In this study, the highest tensile strength printing condition was identified by printing a tensile test specimen using PLA (Poly Lactic Acid) resin, considering various printing conditions. To determine the optimal combination of printing conditions, various machine learning algorithms were compared, and Stochastic Gradient Descent(SGD) demonstrated the best performance in predicting tensile strength. Using SGD, 3,000 sets of printing conditions were generated by combining various parameters, and the best printing condition set was selected. A tensile test specimen was then produced according to the selected printing conditions, and the subsequent tensile test yielded a measured tensile strength value of 41.86 N/mm2. The predicted tensile strength value by the SGD algorithm was 43.34 N/mm2, resulting in a prediction accuracy of 96.23%.

Synthesis and Characteristics of New Quaternary Superhard Ti-Mo-Si-N Coatings (새로운 고경도 Ti-Mo-Si-N 코팅막의 합성 및 기계적 특성)

  • Jeon, Jin-Woo;Hong, Seung-Gyun;Kim, Kwang-Ho
    • Journal of Surface Science and Engineering
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    • v.39 no.6
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    • pp.245-249
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    • 2006
  • In this study, ternary Ti-Mo-N and new quaternary Ti-Mo-Si-N coatings were synthesized on steel substrates(AISI D2) and Si wafers by a hybrid coating system of arc ion plating (AIP) using Ti target and d.c. magnetron sputtering technique using Mo and Si targets in N2/Ar gaseous mixture. Ternary Ti-Mo-N coatings were substitutional solid-solution of (Ti, Mo)N and showed maximum hardness of approximately 30 GPa at the Mo content of 10. %. The Ti-Mo-Si-N coating with the Si content of 8.8 at. % was a composite consisting of fine (Ti, Mo)N crystallites and amorphous Si3N4 phase. The hardness of the Ti-Mo-Si(8.8 at. %)-N coatings exhibited largely increased hardness value of 48 GPa due to the microstructural evolution to the fine composite microstructure and the refinement of (Ti, Mo)N crystallites. The average friction coefficient of the Ti-Mo-Si-N coatings largely decreased with increase of Si content. The microstructures of Ti-Mo-Si-N coatings were investigated with instrumental analyses of XRD, XPS, and HRTEM in this work.

CVD로 성장된 다결정 3C-SiC 박막의 전기적 특성

  • An, Jeong-Hak;Jeong, Gwi-Sang
    • Proceedings of the Korean Society Of Semiconductor Equipment Technology
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    • 2007.06a
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    • pp.179-182
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    • 2007
  • Polycrystaline (poly) 3C-SiC thin film on n-type and p-type Si were deposited by APCVD using HMDS, H2, and Ar gas at 1180C for 3 hour. And then the schottky diode with Au/poly 3C-Sic/Si(n-type) structure was fabricated. Its threshold voltage (Vd), breakdown voltage, thickness of depletion layer, and doping concentration (ND) value were measured as 0.84 V, over 140 V, 61nm, and 2.7×1019cm3, respectively. The p-n junction diode fabricated by poly 3C-SiC was obtained like characteristics of single 3C-SiC p-n junction diode. Therefore, its poly 3C-SiC thin films are suitable MEMS applications in conjuction with Si fabrication technology.

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Gomisin N and Wuweizisu C, new Inhibitors for Chitin Systhase II from Schizandra chinensis (오미자에서 분리한 새로운 Chitin Synthase II 저해제인 Gomisin N 과 Wuweizisu C)

  • 황의일;김미경;이향복;김영국;권병목;배기환;김성욱
    • YAKHAK HOEJI
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    • v.43 no.4
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    • pp.509-515
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    • 1999
  • To search for new chitin biosynthesis inhibitors from natural sources, several higher plants were examined the inhibitory activity against chitin synthase IIby enzymatic assay. Among them, the extract of Schizandra chinensis strongly showed the inhibitory activity against chitin synthase II. Gomisin N and wuweizisu C were isolated from Schizandra chinensis and showed IC50 value of 62.4μg/ml and 19.2μg/ml, respectively. Activities of these compounds were more stronger than that of polyxin D. However, gomisin N and wuweizisu C showed weakly antifungal activities against various human pathogens.

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