• 한국가스학회:학술대회논문집
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• 1997.09a
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• pp.14-19
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• 1997

A numerical method for determining the temperature vartiation in a natural gas transmission line is presented. By considering an element of the gas pipeline and assuming radially lumped heat transfer at steady-state conditions, the energy equation is developed. The integration of the developed nonlinear differential equation is done numerically using the fourth order Runge-Kutta scheme. The results of the present study have been compared with the results of Coulter equations, and show a fairly good agreement.

• Bulletin of the Korean Chemical Society
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• v.29 no.5
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• pp.1065-1068
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• 2008

• Journal of the Semiconductor & Display Technology
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• v.6 no.1 s.18
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• pp.27-30
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• 2007

The gigahertz oscillator behavior of double-walled boron-nitride nanotube (BNNT) was investigated by using classical molecular dynamics simulations. The BNNT oscillator characteristics were compared to carbon-nanotube (CNT) and hybrid-C@BNNT oscillators. The results show that the BNNT oscillators are higher than the van der Waals force of the CNT oscillator. Since the frictional effects of BNNT oscillators are higher than that of a CNT oscillator, the damping factors of BNNT and hybrid oscillators are higher than that of a CNT oscillator.

• Proceedings of the Materials Research Society of Korea Conference
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• 2006.05a
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• pp.20.1-20.1
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• 2006

• Applied Microscopy
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• v.48 no.2
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• pp.43-48
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• 2018

Transition metal dichalcogenide (TMD) materials have distinctive structures in comparison with other two-dimensional materials. TMD materials' structure is held together by van der Waals and covalent intralayer interactions; consequently, TMDs exhibit multiple phases and properties depending on their structure. This article reviews some of the research currently being undertaken to control TMD phases to utilize their different properties. This review introduces some trials for changing the phase of TMDs.

• Proceedings of the Korean Magnestics Society Conference
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• 2005.06a
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• pp.20-21
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• 2005

• Bulletin of the Korean Chemical Society
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• v.17 no.2
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• pp.147-152
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• 1996

To see the quantitative relationship between the structures of the C-7 substituted quinolones and their antibacterial activities, theoretical parameters such as the molecular van der Waals volume, surface area and some electrostatic parameters based on the molecular electrostatic potential, which represent lipophilicity, and some quantum mechanical parameters are introduced as descriptors. The sixteen substituted quinolone derivatives and twenty bacteria are used for the study. It is found that the QSARs of C-7 substituted quinolones are obtained for eleven bacteria and our descriptors are more useful for Gram positive organisms than negative ones. It is also shown that molecular surface area (or molecular Waals volume) of the C-7 substituent and net charge of C-7 atom of the quinolones are the descriptors of utmost importance.

• Korean Journal of Crystallography
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• v.5 no.2
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• pp.108-112
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• 1994

C19H20O5, Mr=314.337, triclinic,PI, a=10.291(2)A, b=11.218(3)A, c=3.059(1)A, α=74.54(2)°, β=1148.84(1)°, r=109.84(2)°, V=883.283(2)A3, λ(Mo Kα)=0.71069A, μ=0.47 mm-1, F(000)=324, 296K, Z=2, Dx=1.18Mgm-3. Final R=0.0580 for 1637[F>3σ(F)]unique refledtions. α,β-diphenylsuccinic acid, C16H14O4, are connedted with the solvent actone by hydrogen bond O(4)-H˙˙˙O(5), forming a dimer related by related by centrosymmentry thorough intermolecualr carboxylic hydrogen bond O(1)-H˙˙˙O(2)(-x,-y,-z). The nearest distance 3.288A[O(2)˙˙˙O(2)(-x,-y,-z)] between the dimers shows that the packing of the dimer is govermed by van der Waals'force.

• Korean Journal of Crystallography
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• v.4 no.1
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• pp.6-10
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• 1993

11 β ,17 β -dihydroxy-9a-fluoro-l7a-methyl androst-4-en-3-one (Fluoxymesterone), CgoH29 FO,, orthorhombic, P2,2,2,, a=13.468(5) A, b= 19.554 (2)A, c=6.578(9)A, a=b=r=90˚, A (CuKa)=1.5406 A , Dm=1.289cm-3, Dc=1.299cm-3 and Z=4 at T=298k. The structure was solved by direct method using seminvariants of ggg Parity group and refined by the full-matrix least-square method, resulting model with reliability factor R=0.069 for 1098 unique reflection over 3σ . Ring A is an 1β-2a-half chair, 5 ring has a highly symmetrical chair conformation, C ring is in a distorted chair conformation and D ring is a 13aenveLope conformation. In the crystal structure, the molecules are packed with a hydrogen bond of 011-H23‥‥03(0.5+x, 1.5-y, 1.0-z) [1.94(9) A of H‥‥0.2.786(9)A of 0‥‥0 and 165(8) ˚ of

• Journal of the Korean Chemical Society
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• v.34 no.2
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• pp.130-135
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• 1990

The title compound (C13H17NO2S) is monoclinic, space group P21/a, with a = 13.756 (3), b = 9.310(4), c = 21.305(3) $\AA$, $\beta$ = 95.0。, Z = 8, V = 2718.11 $\AA$3, Dc = 1.23$g·{\cdot}cm-3$, (Mo k$\alpha$) = 0.71069$\AA$,$\mu$ = 2.18 cm-1, F(000) = 1071.86, T = 298, R = 0.085 for 2935 unique observed reflections with I >2.0$\sigma$(I). The structure was solved by direct methods. The C-H bond lengths and the methyl groups are fixed and refined as their ideal geometry by allowing to ride on the parent atoms. Both molecules A and B have almost same structures except for two terminal ethyl groups. The ethylene-like skeleton including the nitro group in one molecule is nearly perpendicular to the plane of the methylbenzene group and two ethyl groups form a cis-type structure which has the dfferent orientations between two molecules; in the molecule A, two terminal methyl groups being the opposite directional arrangement against the plane of its skeleton, while in the B, with the same directional structure from its plane. The molecules in the crystal are packed together by non-bonded van der Waals forces.