• Title/Summary/Keyword: Kinetic Coefficient

Search Result 324, Processing Time 0.022 seconds

Kinetic Analysis of the Probability of Hexagonal Face in Juryeonggu (주령구에서 육각면이 나올 확률에 대한 운동역학적 해석)

  • Yoo, Wan Suk;Lee, Jeong Han
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.41 no.11
    • /
    • pp.1085-1089
    • /
    • 2017
  • Juryeonggu is a cuboctahedral die that was used during the Silla period in ancient Korea. This cuboctahedral die consists of two different penal servitudes of 14 sides; however, its equal probability distribution enables it to be used as a die. In this paper, a precise cuboctahedral die, Juryeonggu, was manufactured, and its probability was measured through experiments. Next, the probability was verified through Multibody-dynamics (MBD) modeling and analysis, and the effect of the coefficient of friction on the probability distribution was studied.

Kinetics and Mechanism of the Aminolysis of Aryl N-Benzyl Thiocarbamates in Acetonitrile

  • Oh, Hyuck-Keun
    • Bulletin of the Korean Chemical Society
    • /
    • v.32 no.1
    • /
    • pp.137-140
    • /
    • 2011
  • The aminolysis reactions of phenyl N-benzyl thiocarbamate with benzylamines in acetonitrile at $50.0^{\circ}C$ are investigated. The reactions are first order in both the amine and the substrate. Under amine excess, pseudo-first coefficient ($k_{obs}$) are obtained, plot of $k_{obs}$ vs free amine concentration are linear. The signs of ${\rho}_{XZ}$ (< 0) are consistent with concerted mechanism. Moreover, the variations of $\rho_X$ and $\rho_Z$ with respect to the sustituent in the substrate and large ${\rho}_{XZ}$ value indicate that the reactions proceed concerted mechanism. The normal kinetic isotope effects ($k_H/k_D$ = 1.3 ~ 1.5) involving deuterated benzylamine nucleophiles suggest a hydrogen-bonded, four-centered-type transition state. The activation parameters, ${\Delta}H^\ddagger$ and ${\Delta}S^\ddagger$, are consistent with this transition state structure.

The Behavior of a $CO_2$Fixation Process by Euglena Gracilis Z with a Photobioreactor (광반응기와 Euglena gracilis Z를 이용한 이산화탄소 고정화 공정의 거동 특성)

  • 신항식;채소용;황응주;임재림;남세용
    • KSBB Journal
    • /
    • v.15 no.6
    • /
    • pp.644-648
    • /
    • 2000
  • Biological fixation of carbon dioxide using microalgae is known as an effective CO$_2$reduction technology. However, many environmental factors influence microalgal productivity. Optimal cultivation factors were determined for the green alga, Euglena gracilis Z, which offers high protein and vitamin E content for animal fodder. In batch culture in a photovioreactor, it was found that theinitial pH, temperature, CO$_2$concentration in air, and light intensity during the optimal cultivating conditions were 3.5, 27$^{\circ}C$, 5-10% and 520 ${\mu}$mol/㎡/s, respectively. When tap water and freshwater were used as cultivating media unsterilized tap water was found to be effective. A kinetic model was considered to determine the relationship between the specific growth rate and the light intensity. The half-velocity coefficient (K(sub)I) in the Monod model under photoautotrophic conditions was 978.9 ${\mu}$mol/㎡/s.

  • PDF

Analysis of the Solvolysis of Anthraquinone-2-Carbonyl Chloride in Various Mixed Solvents

  • Koh, Han Joong;Kang, Suk Jin
    • Journal of the Korean Chemical Society
    • /
    • v.62 no.4
    • /
    • pp.265-268
    • /
    • 2018
  • The solvolyses of anthraquinone-2-carbonyl chloride (1) were studied kinetically in 27 pure and various mixed solvents. The analysis using the extended Grunwald-Winstein equation in the solvolyses of anthraquinone-2-carbonyl chloride (1) obtained the l value of $2.11{\pm}0.11$, the m value of $0.54{\pm}0.06$, and the correlation coefficient of 0.955. The solvolysis reaction of 1 might proceed via an associative $S_N2$ mechanism enhancing bond making than bond breaking in the transition state (TS). This interpretation is further supported by a relatively large solvent kinetic isotope effect (SKIE, 2.27).

Solvolysis of (1S)-(+)-Menthyl Chloroformate in Various Mixed Solvents

  • Koh, Han Joong;Kang, Suk Jin
    • Journal of the Korean Chemical Society
    • /
    • v.65 no.5
    • /
    • pp.309-312
    • /
    • 2021
  • The solvolysis of (1s)-(+)-menthyl chloroformate (1) were studied kinetically in 28 pure and various mixed solvents. The analysis using the extended Grunwald-Winstein equation in the solvolysis of 1 obtained the l value of 2.46 ± 0.18, the m value of 0.91 ± 0.07, and the correlation coefficient of 0.950. The solvolysis of 1 might proceed via an associative SN2 mechanism enhancing bond making than bond breaking in the transition state (TS). The value of l/m is 2.7 within the ranges of value found in associative SN2 reaction. This interpretation is further supported by a relatively large solvent kinetic isotope effect (SKIE, 2.16).

Kinetic Analysis of Solution Reaction between CR and Silane Coupling Agents (Silane Coupling제(劑)와 고분자탄성체간(高分予彈性體間)의 용액반응(溶液反應)에 대한 속도론적(速度論的) 해석(解析))

  • Park, Young-Su;Yoon, Jeong-Sik;Yoo, Chong-Sun;Paik, Nam-Chul
    • Elastomers and Composites
    • /
    • v.25 no.2
    • /
    • pp.112-116
    • /
    • 1990
  • In this study, as one way of developing the new cross-linking method that is curable in water, kinetic analysis of solution reaction between CR and silane coupling agents was attemped. First, CR was reacted with silane coupling agents in solution state. According to the time, reaction quantity was pursued by gas chromatography. Also, reaction rate coefficient and activation energy were calculated from the reaction quantity. Silane coupling agents which were used in this study were MPS, CPS and VES.

  • PDF

Effects of Steel Fiber, Zircon, and Cashew in the Brake Friction Materials on Creep Groan Phenomena (자동차 브레이크용 마찰재 내의 강철섬유, 지르콘, 캐슈가 크립 그론에 미치는 영향)

  • Jang, Ho;Lee, Kang-Sun;Lee, Eun-Ju;Jeong, Geun-Joong;Song, Hyun-Woo
    • Tribology and Lubricants
    • /
    • v.23 no.6
    • /
    • pp.278-282
    • /
    • 2007
  • Friction characteristics of a low-steel friction material were examined to investigate creep groan phenomena. The amount of three ingredients (steel fiber, $ZrSiO_4$, cashew) were changed to produce test specimens using a constrained mixture design. Tribological properties of the friction material specimens were obtained by using a 1/5 scale dynamometer. Results showed that the amount of three different ingredients strongly affected the level of friction coefficient and the difference between the static friction coefficient and the kinetic friction coefficient $({\Delta}{\mu}).\;ZrSiO_4$ and steel fiber tended to increase the average friction coefficient and aggravated the stick-slip phenomena suggesting high creep groan propensity. On the other hand, cashew tended to decrease average friction coefficient and ${\Delta}{\mu}$.

A Comparative Analysis of the Kinetic Structure in Lectures on a High School Science (고등학교 공통 과학 강의에서 교사에 따른 역동적 구조의 정량적 비교 분석)

  • Yu, Seung-Geun;Lee, Joon-Sang
    • Journal of The Korean Association For Science Education
    • /
    • v.20 no.4
    • /
    • pp.505-509
    • /
    • 2000
  • The kinetic structure of the content of instructions at the unit of 'heart and circulation' in "the common science", which was respectively given by two teachers majored in biology and two teachers majored in earth science was investigated. Concerning of the mean of the fundamental coefficient (B1), the mean of weighted coefficients (B2) and the progression of instruction (P), T4 (B1, 0.14; B2, 0.82; P; 0.86) teacher showed relatively lower kinetic structure and faster progression than those of the others. The other teachers showed a different level of the kinetic structure and progression: T1(B1, 0.21; B2, 0.86; P; 0.79), T2 (B1, 0.02; B2, 0.85; P; 0.80), and T3 (B1, 0.22; B2, 0.83; P; 0.78). T1 teacher who showed the largest total frequency of verbal elements, the great number of sorts of verbal elements and secondary span, had a higher level of the kinetic structure, but T4 teacher showed the lowest level of total frequency of verbal elements, the great number of sorts of verbal elements and secondary span. The main reason why T4 teacher's instruction achieved a lower level of kinetic structure was estimated that he neglected to reorganize teaching materials and he showed a small number of discourse units. In addition, the unit of 'heart and circulation' was less related to T4 teacher's major and T4 teacher had a shorter teaching experience than those of the others. T4 teacher also took charge of only one class, and this did not allow to instruct repeatedly.

  • PDF

Quantitative Kinetic Energy Estimated from Disdrometer Signal (우적 크기 탐지기 신호로 산출한 정량적 운동에너지)

  • Moraes, Macia C. da S.;Sampaio, Elsa;Tenorio, Ricardo S.;Yoon, Hong-Joo;Kwon, Byung-Hyuk
    • The Journal of the Korea institute of electronic communication sciences
    • /
    • v.15 no.1
    • /
    • pp.153-160
    • /
    • 2020
  • The kinetic energy of the rain drops was predicted in a relation between the rain rate and rain quantity, derived directly from the rain drop size distribution (DSD), which had been measured by a disdrometer located in the eastern state of Alagoas-Brazil. The equation in the form of exponential form suppressed the effects of large drops at low rainfall intensity observed at the beginning and end of the rainfall. The kinetic energy of the raindrop was underestimated in almost rain intensity ranges and was considered acceptable by the performance indicators such as coefficient of determination, average absolute error, percent relative error, mean absolute error, root mean square error, Willmott's concordance index and confidence index.

Removal of Sulfamethoxazole using Ozonation or UV Radiation; Kinetic Study and Effect of pH (오존 처리 및 UV 조사를 이용한 Sulfamethoxazole 제거; 동역학적 고찰 및 pH 영향)

  • Jung, Yeonjung;Kim, Wangi;Jang, Hayoung;Choi, Yanghwun;Oh, Byungsoo;Kang, Joonwun
    • Journal of Korean Society on Water Environment
    • /
    • v.24 no.1
    • /
    • pp.63-68
    • /
    • 2008
  • This study was performed to assess the potential use of ozone or UV radiation for the treatment of water contaminated with sulfamethoxazole (SMX), which is frequently used antibiotic in human and veterinary medicines, especially focusing on the kinetic study and effect of pH. In a study using ozone alone, kinetic study was performed to determine second-order rate constant ($k_{O3,SMX}$) for the reactions of SMX with ozone, which was found to be $1.9{\times}10^6M^{-1}s^{-1}$ at pH 7. The removal efficiencies of SMX by ozone were decreased with increase of pH due to rapid decomposition of ozone under the condition of various pH (2.5, 5.3, 7, 8, 10). In a UV irradiation study at 254 nm, a kinetic model for direct photolysis of SMX was developed with determination of quantum yield ($0.08mol\;Einstein^{-1}$) and molar extinction coefficient ($15,872M^{-1}cm^{-1}$) values under the condition of quantum shielding due to the presence of reaction by-products formed during photolysis. For effect of pH on photolysis of SMX, SMX in the anionic state ($S^-$, pH > 5.6), most prevalent form at environmentally relevant pH values, degraded more slowly than in the neutral state (SH, 1.85 < pH < 5.6) by UV radiation at 254 nm.