• Korean Journal of Crystallography
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• v.6 no.1
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• pp.43-48
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• 1995

The crystal structure of P-toluenesulfonanilide, C13H13NO2S is monoclinic, space group P21/c, a=8.777(1)Å, b=9.784(2)Å, c=15.139(2)Å, β=99.00(1)°, Z=4, V=1284.0(6)Å3, Dc=1.28g/cm33, λ(Mo-Kα)=0.71069Å, μ=2.3cm-1, F(000)=520, Temperature : 293±3K, R=0.038 for 711 Fo<3.0σ unique observed reflection. The structure was determuned by direct method and refined by full-matrix least squares refinement. Two benzene rings have the dihedral angle of 68.4°. Moleculs are accumulated according to the c axis with two fold screw and contacted by van der Walls force.

• Bulletin of the Korean Mathematical Society
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• v.52 no.4
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• pp.1327-1338
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• 2015

In this paper, we introduce and study the w-weak global dimension w-w.gl.dim(R) of a commutative ring R. As an application, it is shown that an integral domain R is a $Pr\ddot{u}fer$ v-multiplication domain if and only if w-w.gl.dim(R) ${\leq}1$. We also show that there is a large class of domains in which Hilbert's syzygy Theorem for the w-weak global dimension does not hold. Namely, we prove that if R is an integral domain (but not a field) for which the polynomial ring R[x] is w-coherent, then w-w.gl.dim(R[x]) = w-w.gl.dim(R).

• Communications of the Korean Mathematical Society
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• v.20 no.3
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• pp.437-442
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• 2005

In studying injective covers, the modules C such that Hom(E, C) = 0 and $Ext^1$(E, C) = 0 for all injective module E play an important role because of Wakamatsu's lemma. If C is a module over the ring k[[x, y]] with k a field, the class of these modules C contains the class $\={D}$ of all direct summands of products of modules of finite length ([3, Theorem 2.9]). In this paper we show that every module over any commutative ring has a $\={D}$-preenvelope.

• Journal of the Korea Furniture Society
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• v.20 no.4
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• pp.274-280
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• 2009

The purpose of this study was to identify the species of coffin woods excavated at Mundangdong in Gimcheon and to date this coffin by using tree-ring method. All coffin woods were identified as red pines, most possibly, Pinus densiflora S. et Z. Tree-ring dating provided absolute years of 3 among 19 coffins. Both I-9 and II-22 coffins were estimated to be made in the mid-seventeenth century, and I-65-1 in the mid-sixteenth century. Others possessed too few rings to be dated.

• Journal of the Korean Wood Science and Technology
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• v.18 no.2
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• pp.8-15
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• 1990

This study was carried out to investigate the wood qualities for the end-use development of sycamore (Platanus occidentalis L.) grown in Korea. The results obtained were as follows: 1. The average length of wood fibers was l.56mm and the average width of annual rings was 9.5mm. It had very fast growth rate. 2. The specific gravity in air-dry was 0.66. The shrinkage and water absorption were relatively large. The shear and impact strengthes were very strong, while the compressive, tensile, and bending strengthes were weak in comparison to it's specific gravity. 3. The contents of ash, holocellulose, lignin were relatively high 0.74%, 83.08%, 28.79%, but that of pentosan was low 18.53%. 4. The expected uses of sycamore wood are plywood. fancy veneer, small furniture, musical instrument, door and window frame, tool handels, boxes, etc.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2000.11a
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• pp.17-26
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• 2000

The early investigators into the in-plane vibration of rings were Hoppe $Hoppe ^{1)}$ and $Love ^{2)}$. $Love ^{2)}$ Improved on Hoppe's theory by allowing for stretching of the ring. $Lamb ^{3)}$ investigated the statics of incomplete ring with various boundary conditions and the dynamics of an incomplete free-free ring of small curvature. Den $Hartog ^{4)}$ used the Rayleigh-Ritz method for finding the lowest natural frequency of circular arcs with simply supported or clamped ends and his work was extended by Volterra and $Morell ^{5)}$ for the vibrations of arches having center lines in the form of cycloids, catenaries or parabolas.(omitted)

• Bulletin of the Korean Mathematical Society
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• v.50 no.6
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• pp.1863-1871
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• 2013

For a ring R with an automorphism ${\sigma}$, an n-additive mapping ${\Delta}:R{\times}R{\times}{\cdots}{\times}R{\rightarrow}R$ is called a skew n-derivation with respect to ${\sigma}$ if it is always a ${\sigma}$-derivation of R for each argument. Namely, if n - 1 of the arguments are fixed, then ${\Delta}$ is a ${\sigma}$-derivation on the remaining argument. In this short note, from Bre$\check{s}$ar Theorems, we prove that a skew n-derivation ($n{\geq}3$) on a semiprime ring R must map into the center of R.

• Journal of the Korean Geographical Society
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• v.32 no.1
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• pp.47-68
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• 1997

The purpose of this study is to clarify both the characteristics of the spatial variations and structure and the logic of spatial differentiation of the renter farming in Korea. The renter farming has transformed its spatial structure from zonal to Thunen's rings-like pattern. This study also suggests that the spatial characteristics of the renter farming has been changed from the ecological and the tenantable to the economical and commercial. Although there is no single logic full explanation the order of such spatial differentiations, the logic of industrialization or neoclassical economics seems to be most effective.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.32.2-32.2
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• 2018

We present the structural parameters of ~ 910 dwarf elliptical-like galaxies in the local universe ($z{\lesssim}0.01$) derived from the r-band images of the Sloan Digital SKy Survey (SDSS). We examine the dependence of structural parameters on the morphological types (dS0, dE, dEbc, dSph, and dEblue) and the environment. There is not much difference in the structural parameters among the five subtypes but the mean surface brightness within the effective radius (<${\mu}e$>) of dSph galaxies is clearly different from that of other subtypes. The frequency of disk features such as spiral arm, bar, lens, and rings strongly depends on the morphology of dwarf elliptical-like galaxies with no disk features in dSph galaxies. The absence of disk features and the low surface brightness of dSph galaxies are thought to be closely related to their low mass which leads to different evolution from other subtypes of dwarf elliptical-like galaxies. Density Environments Using IMSNG.

• Bulletin of the Korean Mathematical Society
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• v.28 no.2
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• pp.175-180
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• 1991

In [3], [4] and [5], Hochster and Huneke introduced the notions of the tight closure of an ideal and of the weak F-regularity of a ring. This notion enabled us to give new proofs of many results in commutative algebra. A regular ring is known to be F-regular, and a Gorenstein local ring is proved to be F-regular provided that one ideal generated by a system of parameters (briefly s.o.p.) is tightly closed. In fact, a Gorenstein local ring is weakly F-regular if and only if there exists a system of parameters ideal which is tightly closed [3]. But we do not know whether this fact is true or not if a ring is not Gorenstein, in particular, a ring is a Cohen Macaulay (briefly C-M) local ring. In this paper, we will prove this in the case of an 1-dimensional C-M local ring. For this, we study the F-rationality and the normality of the ring. And we will also prove that a C-M local ring is to be Gorenstein under some additional condition about the tight closure.