• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3317-3320
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• 2012

A novel energetic compound, bifurazano[3,4-b:3',4'-f]furoxano[3'',4''-d] oxacyclohetpatriene (BFFO), was synthesized through special etherification and its structure was determined by single crystal X-ray diffraction. The crystal of $BFFO{\cdot}H_2O$ is monoclinic, space group P2(1)/c with crystal parameters of a = $9.324(4){\AA}$, b = $9.727(4){\AA}$, c = $10.391(4){\AA}$, ${\beta}=106.305(6)^{\circ}$, V = $904.5(6){\AA}^3$, Z = 4, ${\mu}=0.17mm^{-1}$, F(000) = 512 and $D_c=1.866g\;cm^{-3}$. Spectroscopic properties and thermal behaviors of BFFO were studied. BFFO presents good detonation properties.

• Journal of Korea Foundry Society
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• v.3 no.1
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• pp.28-36
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• 1983

In order to study the cast structure and mechanical properties of Al-10 % Mg alloy solidified under the various high hydraulic pressure, ranging from $0kgf/cm^2$ to $2000㎏f/cm^2$ , the relationship between the cooling rate and the cast structure was observed, and also the mechanical test and the measurement of the specific gravity were carried out. From this experiment, results were summerized as follows; 1. The cooling rate of the alloy increased with increase of the applied pressure. 2. The formation of the piping and the porosity in the castings was surpressed by applying the high hydraulic pressure. 3. The dendrite arm spacing decreased with increase of the applied pressure. 4. Mechanical properties and specific gravity increased with the increase of the applied pressure.

• Journal of the Korean Society of Safety
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• v.23 no.4
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• pp.19-24
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• 2008

This paper presents and discusses the experimental results on the F10T high strength bolts used in the T-flange joint structure. The experimental works were carried out for the parameters which are flange web thickness, the distance between bolts, prying ratio. The results show that the working stress imposed to bolts decreases as the flange web thickness increases on the other hand the imposed stress to the bolts increases as the distance between two bolts increases. In other words the strength of the T-flange joint increased as the web flange thickness increases and the distance between two bolts decreases. The prying ratio is increased as the distance between two bolts increases and as the flange web thickness decreases However, the degree of stress decrease in flange thickness variation is not that high as the distance variation between two bolts. Finally the equation for predicting the failure stress in T-flange joint structure using F10T high strength bolts was suggested.

• Journal of the Korean Chemical Society
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• v.9 no.3
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• pp.142-147
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• 1965

The crystal structure of p-phenylenediamine dihydrochloride has been determined from X-ray oscillation and Weissenberg photographs. The crystal is triclinic, space group $C_i1-P{\bar\1},$ with cell dimensions $a = 4.38{\pm}0.02, b = 5.90{\pm}0.02, c = 8.76{\pm}0.03 {\AA}, {\alpha} = 110{\AA}1, {\beta} = 96{\pm}1\; and\; {\gamma} = 101{\pm}1^{\circ}.$ There is one molecule in the unit cell. The atomic coordinates were found by means of two-dimensional Fourier projection and ($F_o-F_c$) projection along the a, b and c axes. The structure of p-phenylenediamine dihydrochloride is discussed in relation to the structures of hexamethylenediamine dihydrochloride, hexamethylenediamine dihydroiodide and ethylenediamine dihydrochloride.

• Korean Journal of Crystallography
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• v.8 no.2
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• pp.132-137
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• 1997

The crystal structure of N,N'-di-tert-butoxycabonyl-2,7-diazabicyclo[3.3.0]oct-4-ene has been determined from single crystal x-ray diffraction study; C16H26N2O4, Triclinic, P1, a=11.119(1) Å, b=13.638(1) Å, c=6.214(1) Å, α=92.14(1)°, β=103.49(1)°, γ=73.35(1)°, V=877.4(2)Å3, T=293(2)K, Z=2, CuKα(λ=1.5418Å). The structure was solved by direct method and refined by full-matrix least squares to a final R=5.38% for 2389 unique observed F0>4σ(F0) reflections and 225 parameters.

• Korean Journal of Crystallography
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• v.13 no.2
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• pp.86-90
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• 2002

The structure of N-(Diphenylmethylene)aminomethylphosphonate has been determined by X-ray diffraction methods. The crystal system is triclinic, space group P(equation omitted), unit cell constants, a＝8.967(2) (equation omitted), b＝9.309(2) (equation omitted), c＝ 10.981(2) (equation omitted), α＝101.42(2)°, β＝92.22(2)°, γ＝92.23(2)°, V=896.8(3) (equation omitted), T＝296 K, Z＝2, D/sub c/＝1.227 Mgm/sup -3/. The intensity data were collected on an Enraf-Nonius CAD-4 Diffractometer with graphite monochromated MoKα radiation (λ＝0.7107(equation omitted)). The molecular structure was solved by direct methods and refined by full-matrix least-squares to a final R＝7.3% for 979 unique observed F/sub o/>4σ(F/sub o/) refections and 209 parameters.

• Korean Journal of Crystallography
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• v.6 no.1
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• pp.27-35
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• 1995

The crystal structure of 1-tert-butoxycarbonyl-4-[N-(tert-butoxycarbonyl)-N-(ethoxycarbonylmethyl)amino]-3-phenylsulfonylpyrrolidind [C24H36O8N2S] has been from single crystal x-ray diffraction study ; C24H36O8N2S triclinic, p1, a=11.363(8)Å, b=11.589(6)Å, c=11.013(10)Å,α=95.32(6)°,β=98.64(7)°,γ=79.57(5)°,V=1406.8(18)Å3, t=293K, Z=2, CuKα(λ=1.5418Å). The molecular structure was solved by diredt method and refined by full-matrix least squares to a final R=9.78% for 3621 unique observed [F≥4σ(F)] reflections and 703 paramenters.

• Korean Journal of Crystallography
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• v.6 no.2
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• pp.98-102
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• 1995

The crystal structure of -Ethyl-1,4-dihydro-7-methyl-1,8-naphthyridin-4-one-3-carboxylic acid [Nalicixic Acid] has been determined from single crystal X-ray diffraction study; C12H12N2O3, monoclinic, P21/c, a=8.910(2)Å, b=13.145(3)Å, c=9.370(3)Å, β =100.06(2)°, V=1080.6Å, T=293K, Z=4, CuKα(λ=1.5418Å). The molecular structure was solved by direct method and refined by full-matrix least squares to a final R=0.055 for 1555 unique observed [F0>4σ(F0)] reflections and 166 parameters. The conformation of the molecule is stabilized by an intramolecular O(17)-H(17)…O(14) hydrogen bond [2.525(2)Å, 144.3(10)°].

• Journal of The Korean Association For Science Education
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• v.10 no.1
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• pp.9-16
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• 1990

This study investigated the effects of variations in the kinetic structure on science knowledge acquisition. According to the rationale of the kinetic structure theory, a communication having high structrue would facilitate greater knowledge acquisition than a presentation with low structure. To testify that hypothesis, a modified non-equivalent pretest posttest control group design was used. Four 10th grade classes (2 classes for each sex) were selected. On the topic of human digestive system, two tape recorded lessons differing in kinetic structure were developed. On n of two was high structure ($\bar{B}_{1}$=0.56), and the other was low structrue ($\bar{B}_{1}$=0.99) Results indicated that the high structure lesson did not show significantly higher score than the low structrue lesson(F=2.225, P<0.137). But when the data were analyzed by sex, only boy students showed the result that the high structure lesson had significantly higher score than the low structure lesson (F=4.785, P<0.009). The results of this study suggest that a high Structure communication will facilitate the science achievement in the case of boy students.

• Bulletin of the Korean Mathematical Society
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• v.55 no.4
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• pp.1189-1208
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• 2018

The aim of this paper is to study the class of ${\Lambda}$-constacyclic codes of length $2p^s$ over the finite commutative chain ring ${\mathcal{R}}_a=\frac{{\mathbb{F}_{p^m}}[u]}{{\langle}u^a{\rangle}}={\mathbb{F}}_{p^m}+u{\mathbb{F}}_{p^m}+{\cdots}+u^{a-1}{\mathbb{F}}_{p^m}$, for all units ${\Lambda}$ of ${\mathcal{R}}_a$ that have the form ${\Lambda}={\Lambda}_0+u{\Lambda}_1+{\cdots}+u^{a-1}{\Lambda}_{a-1}$, where ${\Lambda}_0,{\Lambda}_1,{\cdots},{\Lambda}_{a-1}{\in}{\mathbb{F}}_{p^m}$, ${\Lambda}_0{\neq}0$, ${\Lambda}_1{\neq}0$. The algebraic structure of all ${\Lambda}$-constacyclic codes of length $2p^s$ over ${\mathcal{R}}_a$ and their duals are established. As an application, this structure is used to determine the Rosenbloom-Tsfasman (RT) distance and weight distributions of all such codes. Among such constacyclic codes, the unique MDS code with respect to the RT distance is obtained.