• 대한화학회지
• /
• 제29권3호
• /
• pp.247-251
• /
• 1985

네자리 리간드인 ethylenediamine-N,N'-di-S-${\alpha}$-propionic acid (eddp)의 디클로로 코발트(III) 착물을 공기산화법에 의하여 합성하였다. eddp리간드는 코발트(III) 이온에 매우 입체선택적으로 배위하여 ${\Delta}$-S-cis 이성체만을 형성함이 관찰되었다. 합성된 착물의 구조는 원소분석, 적외선 분광분석법, 핵자기 공명 및 흡수스펙트럼으로 확인되었으며 특히 착물의 절대배열은 핵자기공명 스펙트럼으로 확인하였다.

• 대한화학회지
• /
• 제5권1호
• /
• pp.48-51
• /
• 1961

A calculation of the optical activity of the ${\alpha}$-1,2,3,4,5,6-Hexahalocyclohexane is presented based upon the Kirkwood's polarizability theory of optical rotatory power. The calculated specific rotation of the compound are given in the following table. The close agreements demonstrates the applicability of the polarizability theory to the compounds whose optical activity is due to steric interference. The agreement in sign also confirms the validity of the absolute configuration of the ${\alpha}$-1,2,3,4,5,6-Hexahalocyclohexane given by O. Hassel.

• 한국전산구조공학회논문집
• /
• 제20권1호
• /
• pp.51-56
• /
• 2007

해양구조물에서 많이 사용되는 K-Joint는 그 구조특성으로 인해 응력집중이 발생하며 최적 설계를 위한 가이드라인제시가 요구된다. 형상특성에 따른 응력집중 현상이 다르게 발생함으로 형상을 결정하는 각종 변수인 ${\alpha},\;{\beta},\;{\gamma},\;{\tau},\;{\theta}$의 변화에 따른 조인트의 응력변화를 분석하였다. 수치적인 패라메트릭 연구를 통해 응력 변화 특성을 제시하였고 주요 요소에 따른 최대 응력값도 나타내었고 수치해석 결과를 실험값과 비교하였다.

• Bulletin of the Korean Chemical Society
• /
• 제30권11호
• /
• pp.2535-2541
• /
• 2009

Prebiotic isomaltooligosaccharide preparations contain $\alpha$-D-glucooligosaccharides comprising isomaltooligosaccharides (IMOs) and non-prebiotic maltooligosaccharides (MOs). They are both glucose oligosaccharides characterized by their degree of polymerization (DP) value (from 2 to $\sim$10), linkages types and positions (IMOs: $\alpha$-(1$\rightarrow$2, 3, 6 and in a lower proportion internal 1$\rightarrow$4) linkages, MOs: α-(1$\rightarrow$4) linkages). Their structure is the key factor for their prebiotic potential. In order to determine and elucidate the exact structure of unknown IMOs and MOs, unambiguous assignments of $^{13}C$ and $^1H$ chemical shifts of commercial standards, representative of IMOs and MOs diversity, have been determined using optimized standard one and two-dimensional experiments such as $^1H$ NMR, $^{13}C$ NMR, APT and ${^1}H-{^1}H$ COSY, TOCSY, NOESY and <$^1H-{^{13}}C$ heteronuclear HSQC, HSQC-TOCSY, and HMBC. Here we point out the differential effect of substitution by a glucose residue at different positions on chemical shifts of anomeric as well as ring carbons together with the effect of the reducing end configuration for low DP oligosaccharides and diasteroisotopic effect for H-6 protons. From this study, structural $^{13}C$ specific spectral features can be identified as tools for structural analysis of isomaltooligosaccharides.

• Progress in Superconductivity
• /
• 제12권1호
• /
• pp.41-45
• /
• 2010

Low temperature micro-calorimeters have been employed in the field of high resolution alpha spectrometers. These alpha detectors typically consist of a superconducting or metal absorber and a temperature sensor. The temperature sensor can be a transition edge sensor (TES), a metallic magnetic calorimeter (MMC) or other low temperature detectors for an accurate measurement of temperature change due to an alpha particle absorption. We report a recent study of the heat flow between a replaceable absorber and a temperature sensor. A piece of gold foil in $2.4{\times}2.7{\times}0.03\;mm^3$ is used as an absorber. A $40\;{\mu}m$ diameter Au:Er paramagnetic sensor is attached to another small piece of gold foil in $400{\times}200{\times}30\;{\mu}m^3$ to serve as the temperature sensor. This sensor assembly, Au:Er and gold foil, is placed on a miniature SQUID susceptometer in a gradiometric configuration. The thermal connection between the absorber and the sensor was made with three gold bonding wires. The measured thermal conductance shows a linear dependence to the temperature. The values are in a good agreement with Wiedemann-Franz type thermal conductance of the gold wires.

• Bulletin of the Korean Chemical Society
• /
• 제25권9호
• /
• pp.1314-1320
• /
• 2004

The adsorption and configuration of CO molecules adsorbed on W (110) and W (100) surfaces have been calculated by the atomic superposition and electron delocalization molecular orbital (ASED-MO) method. Referred to as the ASED-MO method, it has been used in the present study to calculate the geometries, binding energies, vibrational frequencies, orbital energies, reduced overlap population (ROP), and charges. From these results adsorption properties of ${\alpha}$-state and ${\beta}$-state were deduced. The calculated binding energies are in good agreement with the experimental result. On the W (110), the calculated average binding energies are 2.56 eV for the end-on configuration and 3.20 eV for the lying-down configuration. Calculated vibrational frequency is 1927 $cm^{-1}$ at a 1-fold site and 1161 $cm^{-1}$ at a long-bridge (2) site. These results are in reasonable agreement with experimental values. On the W(100) surface, calculated average binding energies of the end-on and the lying-down are 2.54 eV and 4.02 eV respectively. The differences for binding energy and configuration on the surfaces are explained on the basis of surface-atom coordination and atom-atom spacing. In the favored lyingdown CO configuration on the W(110) and W(100) surfaces, 4 ${\sigma}$ and 1 ${\pi}$ donation interactions, coupled with the familiar 5 ${\sigma}$ donation to the surfaces and back-donations to the CO 2 ${\pi}^{\ast}$ orbital, are responsible for adsorption to the surface.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2000년도 춘계학술대회 논문집
• /
• pp.71-77
• /
• 2000

The system is defined as groups which are operative, dependentive, configurational of all each others. In oner to develop the AGT system efficiently, the system engineering process has to be organized It will be started by the configuration of WBS and PBS. A WBS is a method of naming and organizing all of the wok elements to be done for a projects. It completely defines the projects, is normally prepared in an hierarchical during design and project execution. A number, or alpha-numeric identification, is assigned to every WBS elements. Also a hierachy of system physical components should be established. It named to PBS, which is a method of naming and organizing all of the physicals elements to be done far a projects. Therefore we will propose the WBS and PBS to fit for AGT system in this reports.

• 한국전산유체공학회지
• /
• 제13권2호
• /
• pp.8-13
• /
• 2008

A supersonic viscous flow over a five-degree half-angle cone is studied computationally with three-dimensional Navier-Stokes equations. Steady asymmetric solutions show that the asymmetric flow separation is caused by convective instability. The effects of angle of attacks, Reynolds numbers, and Mach numbers have been investigated and it is found that those factors affect the generation of the side force. The side force has the maximum value at ${\alpha}=22^{\circ}$, while over ${\alpha}=22^{\circ}$, asymmetric vortex becomes transient, which results in the unsteady shedding. At the angle of attack of 22 degrees, the side force increases with Reynolds number and decreases with Mach number. The increase of the side force stops over the critical Reynolds number for the present configuration.

• 한국전산유체공학회지
• /
• 제11권4호
• /
• pp.48-55
• /
• 2006

A computational study was carried out in order to investigate aerodynamic characteristics on leading edge sweepback angles of Flying-Wing configurations. The viscous-compressible Navire-Stokes equation and Spalart-Allmaras turbulence model of the commercial CFD code were adopted for this computation analysis. This investigation examined aerodynamic characteristics of three different types of leading edge sweepback angles: $30^{\circ}C,\;35^{\circ}C\;and\;40^{\circ}C$. The freestream Mach number was M=0.80 and the angle of attack ranged from ${\alpha}=0^{\circ}C\;to\;{\alpha}=20^{\circ}C$. The results show that the increases in sweepback angle of the Flying-Wing configuration creates more efficient aerodynamic performance.

• Bulletin of the Korean Chemical Society
• /
• 제6권3호
• /
• pp.135-138
• /
• 1985

A new flexible $N_2O_2$-type tetradentate ligand, ethylene-diamine-N,N'-di-${\alpha}$-butyric acid (eddb), has been synthesized, and a series of cobalt (III) complexes of eddb, $[Co(edda)(L)]^{n+}$ (L = $Cl_2$, $(H_2O)_2$, $Cl\;H_2O$, and $Co^2_3$), have been prepared. Only s-cis isomers have been yielded during the preparation of complexes. Ring strain is cited as the primary cause for the preference for the s-cis geometric configuration.