• Journal of Advanced Marine Engineering and Technology
• /
• 제7권1호
• /
• pp.79-90
• /
• 1983

The examination for the changes of structures and mechanical properties in directionally solidified Al-Fe-Ni alloys containing the small amount of Fe and Ni was carried out by the varying the composition and solidification rate R of alloy, provided that the temperature gradient was 80 .deg.C/cm. The result were obtained as follows. A) In proportion to the increase of the solidification rate (R), the crystallized phase of this alloy was changed from the Ribbon-type structure to the Rod-type structure. B) The strength was rapidly increased in the changing process of composite shape from the Ribbon-type to the Rod-type with the solidification rate (R) increasing. C) The fiber stress (${\sigma}^f$) and Young's modulus ($E_f$) calculated for the Rod-type structure were 220 kg/$mm^2$ and 11, 800 kg/$mm^2$ respectively, which were in good accord with the rule of Mixtures.

• Bulletin of the Korean Chemical Society
• /
• 제19권10호
• /
• pp.1095-1099
• /
• 1998

The crystal structure of an acetylene sorption complex of dehydrated fully Mn(Ⅱ)-exchanged zeolite X, Mn46Si100Al92O384·30C2H2 (a=24.705(3) Å) has been determined by single-crystal X-ray diffraction techniques. The structure was solved and refined in the cubic space group Fd3 at 21(l) ℃. The complex was prepared by dehydration at 380 ℃ and 2 x 10-6 Torr for 2 days, followed by exposure to 300 Torr of acetylene gas for 2 h at 24 ℃. The structure was refined to the final error indices, R1=0.060 and R2=0.054 with 383 reflections for which I > 3σ(Ⅰ). In the structure, Mn2+ ions are located at two different crystallographic sites; sixteen Mn2+ ions at site I are located at the centers of the double six rings and thirty Mn2+ ions are found at site Ⅱ in the supercage, respectively. Each of these latter Mn2+ ions is recessed ca. 0.385(2) Å into the supercage from its three-oxygen plane. Thirty acetylene molecules are sorbed per unit cell. Each Mn2+ ion at site Ⅱ lies on a threefold axis in the supercage of the unit cell, close to three equivalent trigonally arranged zeolite framework oxygen atoms (Mn(Ⅱ)-O=2.135(9) Å) and symmetrically to both carbon atoms of a C2H2 molecules. At these latter distances, the Mn(Ⅱ)-C interactions are weak (Mn(Ⅱ)-C=2.70(5) Å), probably resulting from electrostatic attractions between the divalent cations and the polarizable π-electron density of the acetylene molecules.

• 한국결정학회지
• /
• 제6권2호
• /
• pp.63-68
• /
• 1995

X-ray 회절법을 이용하여 fenothiocarb(S-4-phenoxybutyl dimethylthiocarbamate), C13H19NO2S의 결정 및 분자구조를 규명하였다. asetone용액으로부터 얻은 무색 단결정은 단사정계, 공간군은 P21/c이며, a=9.045(1)Å, b=14.577(2)Å, c=10.727(2)Å, β=103.56(1)°, Z=4, V=1375.20(6)Å3, Dc=1.23g/cm3, λ(Mo-Kα)=0.71069Å, μ=2.3cm-1, F(000)=544, temperature : 293±3K, 직접법으로 개략적인 분자모델을 설정하고 1543개의 독립 회절 반점에 완전행렬 최소자승법으로 정밀화하여 최종신뢰도값 R=0.049인 최종적인 분자모형을 구하였다. 분자들은 c축 방향 2회선 나선형으로 이상적으로 충진되어 있으며 분자간은 van der Waals 결합력으로 이루어져 있다.

• 대한화학회지
• /
• 제38권10호
• /
• pp.769-773
• /
• 1994

우유에서 추출한 안지오제닌을 사용하여 Xanthomonas celebensis 5S rRNA의 고차원 구조를 조사하였다. 안지오제닌은 5S rRNA의 단일가닥 부분에 있는 피리미딘 염기들의 먼 쪽으로 있는 3' P-O 에스테르 결합들만을 절단하였다. pH 7.0이고 10 mM의 $Mg^{2+}$이 있을 때 안지오제닌은 5S rRNA의 d 고리에서만 작용하였지만 $Mg^{2+}$이 없을 때는 e 고리를 제외한 모든 고리들(a, b, c, d 고리들)에서 작용하였다. $Mg^{2+}$이 없을 때 $U_{74}$-$G_{75}$와 $U_{77}$-$A_{78}$, $U_{103}$-$A_{104}$ 결합들이 pH 7.0과 pH 3.5에서 모두 안지오제닌의 작용에 매우 민감하였다. 한편 pH 3.5이고 $Mg^{2+}$이 없을 때 안지오제닌이 a 고리의 $C_{17}$-$G_{18}$과 b고리의 $U_{55}$-$G_{56}$ 결합들을 강하게 절단하였다. 이러한 결과들에서 우리는 다음과 같이 결론을 내릴 수 있다. 첫째, 안지오제닌을 5S rRNA의 삼차구조 분석에서의 탐침의 하나로 사용할 수 있음을 알았다. 둘째, 5S rRNA의 d고리의 구조는 $Mg^{2+}$과 $H^+$농도에 따라 변하기 쉽다는 것을 알았다.

• 한국농촌건축학회논문집
• /
• 제17권4호
• /
• pp.49-56
• /
• 2015

This study aims to identify variables (dependent and independent variables) by plane type and area, focusing on the R.C structure planes which were applied to the National Rental Housing Complexes during the 1970-80s; and to investigate differences in residential space compositions depending on the interrelationship between the variables. The results of this study can be summarized as follows: First, an independent variable which had the most influence on the residential space composition was found to be stairs. As dependent variables, bedroom, livingroom, and kitchen showed difference in spatial arrangements. Second, in the case of the front entry type, one-sided arrangements were the most common for the 3L+D.K composition, because livingroom was arranged near the stairs, Disadvantages were: (1) the spatial division of each room was not efficient; and (2) the use of room space was low due to long access to each room. Third, in the case of the rear entry type, no problem was found in arranging bedrooms on the front side. By arranging livingroom as a common space area, the distance of approachability to each room was found to be short and the use of space was excellent. However, disadvantages were: (1) stability was lacking; and (2) privacy was low. Fourth, depending on the location of the stairs, an interaction between bedrooms and the connectivity between livingroom and kitchen were found. Accordingly, there were differences in the size and arrangement of space by plane type.

• Bulletin of the Korean Chemical Society
• /
• 제16권6호
• /
• pp.515-518
• /
• 1995

YSe1.83 was synthesized by vapor transport technique and its crystal structure was determined. The structure was isostructure of LaTe2-x, which was layered structure consisting of two-atom thick layers of YSe with distorted NaCl-type structure and one-atom thick layer of Se. The substructure of YSe1.83 was tetragonal with space group of P4/nmm and a=4.011(2) and c=8.261(3) Å with final R/Rw=6.4/6.9 %. The superstructure with asuper=2a, bsuper=6b and csuper=2c was found. The measurements of electronic and magnetic properties of this compound indicate that it is an electronic insulator and diamagnet.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1990년도 가을 학술발표회 논문집
• /
• pp.179-184
• /
• 1990

This paper presents the recent repair and maintenance techniques of R/C structures in Korea. This paper consists of four parts : the first part introduces the current diagmosis techniques, the second one includes the repair methods and the third one classifies the repair material. Finally a repair case of the R/C structure in a chemical plant in Korea was introduced.

• 대한수학회논문집
• /
• 제13권3호
• /
• pp.545-560
• /
• 1998

Let ø and A be denoted by the structure tensor field of type (1,1) and by the shape operator of a real hypersurface in a complex space form $M_{n}$ (c), c $\neq$ 0 respectively. The main purpose of this paper is to prove that if a real hypersurface in $M_{n}$ (c) satisfies $R_{ξ}$ øA = $AøR_{ξ}$, then the structure vector field ξ is principal, where $R_{ξ}$ / is the Jacobi operator with respect to ξ.

• 통합자연과학논문집
• /
• 제9권4호
• /
• pp.255-260
• /
• 2016

The crystal structure of the saliciline derivatives N,N'-bis(3-chloro-2-methylsalicylidene)-1,4-butanediamine ($C_{20}H_{22}Cl_2N_2O_2$) has been determined from single crystal X-ray diffraction data. In the title compound crystallizes in the triclinic space group $P{\bar{i}}$ with unit cell dimension $a=4.6085(3){\AA}$, $b=5.9747(3){\AA}$ and $c=5.9747(3){\AA}$ [${\alpha}=83.889(4)^{\circ}$, ${\beta}=86.744(5)^{\circ}$ and ${\gamma}=82.085(5)^{\circ}$]. The title compound is essentially planar conformation. The compound lies across a crystallographic inversion centre and adopts E configurations with respect to the C-N bonds. The crystal packing of the molecules of compound is stabilized through weak O-H...N intra molecular interactions

• 한국세라믹학회지
• /
• 제12권3호
• /
• pp.8-12
• /
• 1975

The crystal structure of synthetic magnesite has been studied by X-ray method. Magnesite is trigonal R3c, with a=4.637$\AA$, c=15.023$\AA$ and Z=6. Intensity data were collected with a Rigaku automated four-circle diffractometer and Mo-K$\alpha$ radiation. The structure was refined by the full-matrix least squares method using anisotropic thermal parameters. The final R index for 234 reflections is 0.037. The C-O and Mg-O bond lengths were 1.283 and 2.105$\AA$, respectively. The interatomic angles of three kinds of O-Mg-O were 88.25, 91.75 and 180.00$^{\circ}$, respectively. It is clarified that the distortion of the Mg-O6 octahedron in magnesite is smaller than that of Ca-O6 in calcite.