• Title/Summary/Keyword: MO theoretical study

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A Study on the Selection of Variogram Using Spatial Correlation

  • Shin, Key-Il;Back, Ki-Jung;Park, Jin-Mo
    • Communications for Statistical Applications and Methods
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    • v.10 no.3
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    • pp.835-844
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    • 2003
  • A difficulty in spatial data analysis is to choose a suitable theoretical variogram. Generally mean squares error(MSE) is used as a criterion of selection. However researchers encounter the case that the values of MSE are almost the same whereas the estimates of parameters are different. In this case, the selection criterion based on MSE should take into account the parameter estimates. In this paper we study on the method of selecting a variogram using spatial correlation.

Theoretical Study of Phosphoryl Transfer Reactions

  • Han, In-Suk;Kim, Chan-Kyung;Lee, Hai-Whang
    • Bulletin of the Korean Chemical Society
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    • v.32 no.3
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    • pp.889-893
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    • 2011
  • The energetics and transition state (TS) structures of the reactions of six substrates, $R_1R_2P$(=O or S)Cl-type where $R_1=R_2$=Me and/or MeO, with ammonia in acetonitrile are theoretically investigated at the level of CPCM-MP2/6-31+G(d) and CPCM-MP2/6-311+G(3df,2p). The degrees of distortion of TS from the ideal trigonal bipyramidal pentacoordinate, ${\Delta}{{\delta}}_{{\neq}b}$ for a backside and ${\Delta}{{\delta}}_{{\neq}f}$ for a frontside attack, are calculated. The results of calculation suggest that the feasibility of a frontside attack for P=S is greater than that for P=O system when the two ligands, $R_1$ and $R_2$, becomes larger. The experimental and calculated results of anilinolyses of $R_1R_2P$(=O or S)Cl-type show the consistent tendencies.

Theoretical evaluation of Cox's interaction model of client health behavior for health promotion in adult women

  • Kim, Youlim;Lee, Hyeonkyeong;Ryu, Gi Wook
    • Women's Health Nursing
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    • v.26 no.2
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    • pp.120-130
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    • 2020
  • This study aimed to evaluate Cox's interaction model of client health behavior (IMCHB) as used in studies on women's health. Using keyword combinations of "women" and "IMCHB" or "interaction model of client health behavior," we searched the PubMed, MEDLINE, Embase, and RISS databases for studies on the promotion of women's health published from January 2009 to April 2019. Finally, 11 studies were selected and evaluated according to seven criteria for theory evaluation, which combined Fawcett's theory evaluation criteria and Chinn and Kramer's criteria. We found that the IMCHB corresponds to a verifiable practical level of a middle-range theory, although it may be partially abstract. It contains all four concepts of the metaparadigm of nursing, in terms of a holistic philosophical approach. A theoretical evaluation demonstrated that the IMCHB has significance, generality, testability, empirical adequacy, and pragmatic adequacy for nursing practice and research. However, the lack of clear conceptual definitions and the presence of complex relationships among concepts resulted in a lack of internal consistency and parsimony. According to an in-depth verification through a review of the literature, the IMCHB has been used as a health promotion intervention strategy for various populations of women and has led to useful results in nursing practice. The IMCHB was confirmed to be a suitable theory for experimental and clinical research. Future research can build on this middle-range theory for women's health research and practice.

Flow behavior characteristics according to superficial gas velocity of NiO/MoO3/MoS2 (NiO/MoO3/MoS2의 공탑속도에 따른 유동화 특성)

  • Lee, Jae-Rang;Hasolli, Naim;Jeon, Seong-Min;Lee, Kang-San;Lee, Kwan-Young;Kim, Kwang-Deuk;Park, Young-Ok
    • Particle and aerosol research
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    • v.13 no.2
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    • pp.79-85
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    • 2017
  • This study identified the loss of minimum fluidization velocity and pressure in accordance with the superficial velocity of $NiO/MoO_3/MoS_2$, a rare metallic oxide and high value-added material in the lab-scale fluidized bed reactor (L=0.25 m, D=0.05 m). The average pressure loss in L/D 1, 2, and 3 of $NiO/MoO_3/MoS_2$ within the scope of superficial gas velocity between 0.07 and 0.45 m/s based on the L/D 1, 2, and 3 of the specimen was shown to be 290~1952 Pa at decreasing flux and 253~1925 Pa at increasing flux. The comparison between the theoretical value proposed by Wen and the test data showed a difference between 0.021~0.36 magnification. Based on these results, this study was able to determine the operation conditions where rare metallic oxides could be applied in real phenomena.

The Relationship Between Parent and Peer Attachment on SNS Addiction Proneness among Adolescents: The Mediating Effect of the Fear of Missing Out (청소년의 부모 및 또래애착과 SNS 중독경향성의 관계: 소외에 대한 두려움(FoMO)의 매개효과)

  • Han, Da-Jung;Kim, Bin-Na
    • Korean Journal of School Psychology
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    • v.17 no.3
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    • pp.243-261
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    • 2020
  • Fear of missing out (FoMO) refers to the desire to stay continually connected with what others are doing because they are afraid of missing the flow or not being included. Although FoMO has been recently proposed as a widespread phenomenon within social media, there has been few empirical research by which mechanism FoMO leads to social networking service (SNS) addiction. Therefore, this study examined whether FoMO mediated the relationship between adolescents' attachment and SNS addiction proneness. A total of 517 middle and high school students participated in the study and completed self-report questionnaires. Results showed that FoMO partially mediated the relationship between adolescents' parental attachment and SNS addiction proneness, whereas the relationship between adolescents' peer attachment and SNS addiction proneness was fully mediated by FoMO. These results suggest that unstable attachment might contribute to SNS addiction through FoMO, especially in case of peer attachment. Lastly, we discussed theoretical and practical implications of this study and suggestions for future research.

Determination of Reactivity by MO Theory (XX). An MO Theoretical Study on Mechanism of Thiocarbonyl Addition.

  • Lee, IK-Choon;Yang, Ki-Yull
    • Bulletin of the Korean Chemical Society
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    • v.2 no.4
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    • pp.132-138
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    • 1981
  • Ab initio molecular orbital calculations have been performed in an effort to determine which types of chemical interactions play essential roles for the system, , $H_2O+CH_2SH^+$, and $H_2O+ CH_2S$. The most important contribution to the interaction energy in controlling reaction path is the exchange repulsion energy, EX, which is largely responsible for the shape of the total interaction energy curve. In the ion-molecule reaction, prior protonation of thioformaldehyde or prior deprotonation of water leads to formation of the corresponding ionic adducts ($H_2O+CH_2SH$ and $HOCH_2S^-$), with no barrier to reaction, simulating specific acid and base catalysis, respectively, as in the case of formaldehyde. Otherwise, approach of water to thioformaldehyde gives rise to a completely repulsive interaction.

An Experimental And Theoretical Study on the Corrugated Water-Trickle Collector (파형단면을 가진 유하식 집열기의 이론 및 실험 연구)

  • Lee, Jong-Ho;Chung, Mo;Park, Won-Hoon
    • Solar Energy
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    • v.7 no.1
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    • pp.42-52
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    • 1987
  • 파형 단면을 가진 유하식 집열기의 이론 및 실험 결과로서 유량, 각도등 집열성능에 미치는 영향등이 고려되었다. 입구 온도와 출구온도 차이가 적을 경우에는 이론과 실험치가 잘 맞으나 온도차이가 많을 경우 혹은 입구온도가 높을 때에는 투과체안에 생기는 결로 및 수증기의 영향으로 편차가 커진다. 개방회로와 폐쇄회로의 경우를 구분하여 실험되었는데 개방회로의 경우 효율은 약간 저하되지만 전반적인 성능은 폐쇄회로와 같은 경향을 나타내었다. 개방회로는 과열을 막는 방편으로 이용될 수 있다.

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A Study on Threshold Ferroelastic Switching Force of β-Tb2(MoO4)3 Single Crystal (β-Tb2(MoO4)3 단결정의 문턱 강탄성 스윗칭력에 관한 연구)

  • Lee, Su Dae;Lee, Chan Ku;Mun, Jung Hak
    • Journal of Korean Ophthalmic Optics Society
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    • v.2 no.1
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    • pp.1-8
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    • 1997
  • When a ferroelastic domain of ${\beta}-Tb_2(MoO_4)_3$ single crystal is switched from $S_k$ state to $S_p$ state by external force, the formulae that can calculate relativistic displacement of the lattice point and distribution of ferroelastic switching force were derived by this study. The formulae that can calculate threshold switching force in any direction were derived from the conservation law of enthalpy and measured value of threshold switching force in specific direction. Theoretical values of threshold switching force were in accord with measured values at (${\theta}=90^{\circ}$, ${\phi}=15^{\circ}$), (${\theta}=90^{\circ}$, ${\phi}=30^{\circ}$), (${\theta}=90^{\circ}$, ${\phi}=45^{\circ}$), (${\theta}=90^{\circ}$, ${\phi}=60^{\circ}$), (${\theta}=90^{\circ}$, ${\phi}=75^{\circ}$).

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DFT Calculations for the Hydrogen Transfer Reaction in Bis(μ-oxo)dicopper-enzyme (DFT방법을 이용한 Bis(μ-oxo)dicopper-enzyme의 수소이동반응 연구)

  • Park, Ki-soo;Kim, Yong-Ho
    • Journal of the Korean Chemical Society
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    • v.53 no.5
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    • pp.499-504
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    • 2009
  • Metals have often played important roles to some enzymatic reactions that are essential to biological processes. Therefore many scientists have studied the reaction mechanisms of catalytic reactions in metaloenzymes for many years. Methane MonoOxygenase (MMO) is an enzyme that oxidize methane to methyl alcohol. Recently Tolman et al. studied a model reaction for MMO, which is a hydroxide transfer reaction in Bis-($\mu$-oxo)-dicopper complex, and suggested several possible mechanisms. Later a two-step mechanism, which is hydrogen transfer followed by hydroxide rebound, was proposed from theoretical studies. In this study we calculated the reactant, product, and the transition state structures, and energetics of the first hydrogen transfer reaction using various DFT methods including recently developed the MO6 family of DFT, namely, MO6, MO6L, and MO6-2X. We found that the M06/6-31G(d,p)/LANL2DZ method reproduce the experimental XRD structure of reactants very well. The TS structures, barrier heights, and reaction energies depend very much on the size of the basis sets.

Evaluations of Si based ternary anode materials by using RF/DC magnetron sputtering for lithium ion batteries

  • Hwang, Chang-Muk;Park, Jong-Wan
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.08a
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    • pp.302-303
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    • 2010
  • Generally, the high energy lithium ion batteries depend intimately on the high capacity of electrode materials. For anode materials, the capacity of commercial graphite is unlike to increase much further due to its lower theoretical capacity of 372 mAhg-1. To improve upon graphite-based negative electrode materials for Li-ion rechargeable batteries, alternative anode materials with higher capacity are needed. Therefore, some metal anodes with high theoretic capacity, such as Si, Sn, Ge, Al, and Sb have been studied extensively. This work focuses on ternary Si-M1-M2 composite system, where M1 is Ge that alloys with Li, which has good cyclability and high specific capacity and M2 is Mo that does not alloy with Li. The Si shows the highest gravimetric capacity (up to 4000mAhg-1 for Li21Si5). Although Si is the most promising of the next generation anodes, it undergoes a large volume change during lithium insertion and extraction. It results in pulverization of the Si and loss of electrical contact between the Si and the current collector during the lithiation and delithiation. Thus, its capacity fades rapidly during cycling. Si thin film is more resistant to fracture than bulk Si because the film is firmly attached to the substrate. Thus, Si film could achieve good cycleability as well as high capacity. To improve the cycle performance of Si, Suzuki et al. prepared two components active (Si)-active(Sn, like Ge) elements film by vacuum deposition, where Sn particles dispersed homogeneously in the Si matrix. This film showed excellent rate capability than pure Si thin film. In this work, second element, Ge shows also high capacity (about 2500mAhg-1 for Li21Ge5) and has good cyclability although it undergoes a large volume change likewise Si. But only Ge does not use the anode due to its costs. Therefore, the electrode should be consisted of moderately Ge contents. Third element, Mo is an element that does not alloys with Li such as Co, Cr, Fe, Mn, Ni, V, Zr. In our previous research work, we have fabricated Si-Mo (active-inactive elements) composite negative electrodes by using RF/DC magnetron sputtering method. The electrodes showed excellent cycle characteristics. The Mo-silicide (inert matrix) dispersed homogeneously in the Si matrix and prevents the active material from aggregating. However, the thicker film than $3\;{\mu}m$ with high Mo contents showed poor cycling performance, which was attributed to the internal stress related to thickness. In order to deal with the large volume expansion of Si anode, great efforts were paid on material design. One of the effective ways is to find suitably three-elements (Si-Ge-Mo) contents. In this study, the Si based composites of 45~65 Si at.% and 23~43 Ge at.%, and 12~32 Mo at.% are evaluated the electrochemical characteristics and cycle performances as an anode. Results from six different compositions of Si-Ge-Mo are presented compared to only the Si and Ge negative electrodes.

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