• Bulletin of the Korean Chemical Society
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• 제27권9호
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• pp.1405-1417
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• 2006

The geometrical structures, potential energy surfaces, and energetics for the ligand exchange reactions of tetracoordinated platinum $(PtY_2L_2\;:\;Y,\;L=Cl^-,\;OH^-,\;OH_2,\;NH_3)$ complexes in the ligand-solvent interaction systems were investigated using the ab initio Hartree-Fock (HF) and Density Functional Theory (DFT) methods. The potential energy surfaces for the ligand exchange reactions used for the conversions of $(PtCl_4\;+\;H_2O)^{^\ast_\ast}\;to\;[PtCl_3(H_2O)\;+\;Cl^-]$ and $[Pt(NH_3)_2Cl_2\;+\;H_2O]$$[Pt(NH_3)_2Cl_2\;+\;H_2O]$ to $[Pt(NH_3)_2Cl(H_2O)\;+\;Cl^-] $ were investigated in detail. For these two exchange reactions, the transition states $([PtY_2L_2{\cdot}{\cdot}{\cdot}L^\prime])^{^\ast_\ast} $ correspond to complexes such as $(PtCl_4{\cdot}{\cdot}{\cdot}H_2O)^{^\ast_\ast}$ and $[Pt(NH_3)_2Cl_2{\cdot}{\cdot}{\cdot}H_2O]^{^\ast_\ast}$, respectively. In the transition state, $([PtCl_4{\cdot}{\cdot}{\cdot}H_2O]^{^\ast_\ast}$ and $[Pt(NH_3)_2Cl_2{\cdot}{\cdot}{\cdot}H_2O]]^{^\ast_\ast})$ have a kind of 6-membered $(Pt-Cl{\cdot}{\cdot}{\cdot}HOH{\cdot}{\cdot}{\cdot}Cl)$ and $(Pt-OH{\cdot}{\cdot}{\cdot}Cl{\cdot}{\cdot}{\cdot}HN)$ interactions, respectively, wherein a central Pt(II) metal directly combines with a leaving $Cl^-$ and an entering $H_2O$. Simultaneously, the entering $H_2O$ interacts with a leaving $Cl^-$. No vertical one metal-ligand interactions $([PtY_2L_2{\cdot}{\cdot}{\cdot}L^\prime]) $ are found at the axial positions of the square planar $(PtY_2L_2)$ complexes, which were formed via a vertically associative mechanism leading to $D_{3h}$ or $C_{2v}$-transition state symmetry. The geometrical structure variations, molecular orbital variations (HOMO and LUMO), and relative stabilities for the ligand exchange processes are also examined quantitatively. Schematic diagrams for the dissociation reactions of {PtCl4(H2O)n(n=2,4)} into {$PtCl_3(H_2O)_{(n-2)}\;+\;Cl^-(H_2O)_2$} and the binding energies {$PtCl_4(H_2O)_n$(n = 1-5)} of $PtCl_4$ with water molecules are drawn.

• 한국세라믹학회지
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• 제40권9호
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• pp.867-873
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• 2003

$Si_{3}N_{4}$-BN계 기계 가공서 세라믹스를 $1800^{\circ}C$에서 2시간동안 25MPa의 압력하에서 열간 가압소결하여 제조하였다. $Si_{3}N_{4}$ 매트릭스에 판상의 h-BN 첨가량을 5-30 vol%까지 증가함에 따라 굽힘강도는 $Si_{3}N_{4}$ 단미의 1000 MPa에서 720~400 MPa로 감소하였고, 파괴인성도 $Si_{3}N_{4}$ 단미의 7.6MPaㆍ$m^{1/2}$에서 6.5~4.1 MPaㆍ$m^{1/2}$로 감소하였다. $\beta$-$Si_{3}N_{4}$의 결정립 크기와 형상비는 h-BN 첨가에 의해 약간 감소하였다. $Si_{3}N_{4}$ 단미는 절삭시 취성 파괴를 나타내어 절삭이 불가능하였으나, $Si_{3}N_{4}$-BN계 기계 가공서 세라믹스는 파괴가 발생하지 않으면서 절삭이 가능하여, 우수한 기계 가공성을 나타내었다. h-BN 함량이 증가할수록 절삭과 마이크로 드릴링시의 절삭력은 감소하였다.

• 한국결정학회지
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• 제11권2호
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• pp.71-74
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• 2000

The title compound, [Cr(OC3H6N2)6](NO3)3·4H2O, was crystallized in the centrosymmetric space group P with two half molecules in an asymmetric unit, and the two complete molecules are generated by inversion symmetry located at Cr atoms. Therefore, the Cr atoms are coordinated to six imidazolidone ligands through the oxygen atoms, and both CrO6 units have a slightly distorted octahedral geometry.

• 대한화학회지
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• 제57권4호
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• pp.447-454
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• 2013

In this research, two new complexes of N-(2-aminoethyl)-1,3-propanediamine (aepn), $[Cd(aepn)_2]I_2$ (1) and $[Cd(aepn)_2]Cl_2{\cdots}H_2O$ (2), were prepared and identified by elemental analysis, FT-IR, Raman spectroscopy and single-crystal X-ray diffraction. Geometry around the cadmium atom in two complexes by coordination of six nitrogen atoms of two aepn is distorted octahedral. If distortion in the mer-$[Cd(aepn)_2]^{2+}$ cation is disregarded, it has a $C_2$ axis and $C_2$ symmetry. The cyclic voltammetry experiments were carried out to study the complexation process. Two structural surveys on coordination modes and complexes of aepn are presented. A study was carried out using CSD data to estimate the averages of bond lengths for different types of the Cd-N bonds. It was found that the intermolecular $N-H{\cdots}I$, $C-H{\cdots}I$ hydrogen bonds in 1 and $N-H{\cdots}Cl$, $N-H{\cdots}O$, $C-H{\cdots}O$, $O-H{\cdots}Cl$ in 2 stabilized the crystal networks.

• 대한화학회지
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• 제22권3호
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• pp.150-157
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• 1978

N-(p-nitrophenyl)-benzohydrazonyl azide (p-$CH_3,\;p-CH_3O,\;p-NO_2$, p-Cl, p-Br) 유도체들의 가수분해 반응 속도상수를 $25^{\cicr}C$의 50% dioxane 수용액속에서 자외선 분광광도법으로 측정하여 넓은 pH 범위에서 잘맞는 반응속도식을 구하였다. 위 반응속도식과 가수분해 반응속도에 미치는 치환기 효과를 검토하기 위하여 Hammet의 식에 도시한 결과 pH 5.0 이하에서는 $\rho$ = -0.47을, pH 7.0 이상에서는 $\rho$ = 0.68을 얻었다. 또한 반응속도에 미치는 염의 효과, 용매효과, 그리고 azide ion 효과로부터 이 가수분해 반응은 pH 5.0 이하에서는 $S_N1$ 반응, pH 7.0 이상에서는 hydrazonyl azide에 hydroxide 이온이 직접 반응하는 $S_N2$ 반응이 일어나며 pH 5.0와 pH 7.0 사이에서는 이 두반응이 서로 경쟁적으로 반응함을 알 수 있었다.

• 전기학회논문지
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• 제66권2호
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• pp.370-378
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• 2017

A fluid model of 2D axis-symmetry based on inductively coupled plasma (ICP) reactor using $N_2/NH_3/SiH_4$ gas mixture has been developed for hydrogenated silicon nitride ($SiN_x:H$) deposition. The model was comprised of 62 species (electron, neutral, ions, and excitation species), 218 chemical reactions, and 45 surface reactions. The pressure (10~40 mTorr) and gas mixture ratio ($N_2$ 80~96 %, $NH_3$ 2~10 %, $SiH_4$ 2~10 %) were considered simulation variables and the input power fixed at 1000 W. Different distributions of electron, ions, and molecules density were observed with pressure. Although ionization rate of $SiH_2{^+}$ is higher than $SiH_3{^+}$ by electron direct reaction with $SiH_4$, the number density of $SiH_3{^+}$ is higher than $SiH_2{^+}$ in over 30 mTorr. Also, number density of $NH^+$ and $NH_4{^+}$ dramatically increased by pressure increase because these species are dominantly generated by gas phase reactions. The change of gas mixture ratio not affected electron density and temperature. With $NH_3$ and $SiH_4$ gases ratio increased, $SiH_x$ and $NH_x$ (except $NH^+$ and $NH_4{^+}$) ions and molecules are linearly increased. Number density of amino-silane molecules ($SiH_x(NH_2)_y$) were detected higher in conditions of high $SiH_x$ and $NH_x$ molecules density.

• 복식
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• 제50권3호
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• pp.87-104
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• 2000

The women's apparel sizing system, currently used in the Korean industry, does not reflect measurement differences associated with varying body types and age. Forty five body meaqsurements were taken on 560 subjects, whoes eages ranged from 18-24. STatistical analysis of the data was coducted by using frequences, crosstables, correlation, oneway ANOVA, Regressio analysis. The results of this study were as follow. 1. Average height of women in their early 20's is 160cm, average bust girth 82cm, average hip girth 90cm and average drop 809. The correlation between height and grth items were low and the correlation of length items in the superior and inferior body were shown to bo high respectively. 2. The average Rhrer index is 1.28 and they ussually seem to be in the thin and standard body group. 3. body types were divided by differences between hip and bust sizes. N type(medium hip), A type (large hip), H type(small hip). A classification by body type showed that N type made up 58% while a type made up 24%. 4. The garment sizes for women in their early 20's were developed. 5. The new basic blocks and garment sizes for women in their early 20's were developed as follows : Bust girth (1/2) = 76N, 76A, 79A type($\frac{1}{2}$B+ 4cm) 79N type($\frac{1}{2}$B+ 3.5cm) 82N, 85N type ($\frac{1}{2}$B +3cm) Hip girth($\frac{1}{2}$) =N type($\frac{1}{2}$H + 2~2.5cm) Atype($\frac{1}{2}$H +1.5~2cm) Waist girth($\frac{1}{2}$)=$\frac{1}{2}$W + 2-3cm Back length =extimated measure -0.5cm Front length=76A, N (Back length + 2.2cm) 79A, N(back length +2.7cm) 82N(Back length +3.2cm) 85N(Back length + 3.7cm) Sleeve length=Sleeve length +3cm.

• Nuclear Engineering and Technology
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• 제16권2호
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• pp.58-63
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• 1984

특별히 제작한 영동장치를 써서 8면체 구조의 (Ruc $l_{6}$)$^{3-}$ 를 여과지 전기영동 분리하였다. 자지전해질 용액은 다음과 같다. 0.1M-HCl $O_4$, 0.05M-HCl+0.09M-KCI, 0.1M-HCl, 5$\times$$10^{-3}$M-NTA, 0.01M-HCl, 0.01M-HCl $O_4$, 0.01M-시트르산, 0.01M-K $H_2$P $O_4$+0.01M-$Na_2$HP $O_4$, 0.05M-붕사, 0.025M-$Na_2$C $O_3$+0.025M-NaHC $O_3$, 0.01M-$Na_3$P $O_4$, 0.01M-NaOH, 0.1M-NaOH. (Ruc $l_{6}$)$^{3-}$ 은 2-4피크로 나타내며 다음 화학종으로 확인된다. (RuCl($H_2O$)$_{5}$ )$^{2+}$, cis- 및 trans-(RuC $l_2$($H_2O$)$_4$)$^{1+}$ , (RuC $l_3$($H_2O$)$_3$)$^{0}$ , (RuC $l_4$($H_2O$)$_2$)$^{1-}$, (RuC $l_{5}$ ($H_2O$))$^{2-}$ , (RuC $l_{6}$)$^{3-}$ . 리텐숀 값은 0.025M-$Na_2$C $O_3$+0.025M-NaHC $O_3$ 전해질 용액에서 가장 높다.

• 한국세라믹학회지
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• 제27권6호
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• pp.799-807
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• 1990

In this study, effects of oxide additives on mechanical properties and microstructure of A1N and A1N polytype ceramics were investigated. Fine A1N powder was synthesized by nitriding alumiuim hydroxide prepared from Al-isopropoxide, at 1350$^{\circ}C$ for 10h in N2 atmosphere. By adding 3w/o Y2O3, 0.56w/o CaO, and 10w/o SiO2 to AlN powder, AlN and AlN polytype ceramics were prepared by hot-pressing under the pressure of 30 MPa at 1800$^{\circ}C$ for 1h. AlN ceramics with no additives formed considerable amount of AlON phase, while AlN ceramics doped with Y2O3 or CaO decreased AlON phase and formed Y-Al or Ca-Al oxide compound. AlN＋10w/o SiO2(＋3w/o Y2O3) composition produced AlON and AlN polytype compound having 21R as a major phase. Room temperature flexural strength of AlN ceramics with no additive was 246MPa, and room temperature flexural strength and critical temperature difference by thermal shock(ΔTc) of AlN ceramics dooped with Y2O3 or CaO were 532MPa/340$^{\circ}C$ and 423MPa/300$^{\circ}C$, respectively. Y2O3 and CaO used as sintering agent played roles of densification and oxygen removal of AlN ceramics, and affected grain growth/grain morphologies of AlN ceramics.

• Bulletin of the Korean Chemical Society
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• 제22권2호
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• pp.159-163
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• 2001

Si3N4 powder has been analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES). The sample was dissolved by high-pressure acid digestion with HF, H2SO4 (1+1), and HNO3 mix ture. This technique is well suited for the impurity analysis of Si3N4 because the matrix interference is eliminated. A round-robin samples trace elements, such as Ca, W, Co, Al, Fe, Mg, and Na, were determined. For the direct analysis, slurry nebulization of 0.96 mm Si3N4 powder also has been studied by ICP-AES. Emission intensities of Fe were measured as ICP operational conditions were changed. Significant signal difference between slurry particles and aqueous solution was observed in the present experiment. Analytical results of slurry injection and high-pressure acid digestion were compared. For the use of aqueous standard solution for calibration, k-factor was determined to be 1.71 for further application.