• Title/Summary/Keyword: T. B. Lee

Search Result 4,174, Processing Time 0.039 seconds

Evaluation on the In-plane Bending Moment for T-joints with Square Hollow Structural Sections (각형강관 T형 접합부의 면내 휨모멘트 평가)

  • Park, Keum Sung;Lee, Sang Sup;Choi, Young Hwan;Bae, Kyu Woong
    • Journal of Korean Society of Steel Construction
    • /
    • v.21 no.5
    • /
    • pp.451-459
    • /
    • 2009
  • The purpose of this study was to evaluate the in-plane bending moment for T-joints made of cold-formed square hollow steel sections. In the previous studies, the T-joint was shown not to have an obvious peak load, and the failure mode was the main chord flange failure at the branch-width-to-chord-width ratio ($\beta$) of below 0.71. Based on the experimental results, including the tests conducted by Zhao, the deformation limit of 1% B was proposed for ${16.7{\leq}2{\gamma}(=B/T){\leq}33}$ and ${0.34{\leq}{\beta}(=b_{1}/B){\leq}0.71}$. Then, the ultimate in-plane bending strength was shown to be Mu=1.5${\cdot}$M1% B. The existing strength formulae for the original T-joint were investigated and were determined to be the main chord flange failure for the branch-squared T-joint. The bending strength formulae of CIDECT and other researchers were compared with the test results. Finally, a reasonably good agreement with Zhao's formula was found. Therefore, the design guidelines were presented based on Zhao's strength formula for T-joints.

Calculation of the Magnetic Moments for Transition Metal Complexes (Ⅱ). The Magnetic Moments for Distorted Octahedral $[V(III)A_3B_3]$ Type Complexes and the Contribution of $^3T_1$ Term to the Dipole Moments and Polarizability [A and B = O, Cl, N or Br] (전이원소착물의 자기모멘트의 계산 (제2보). $t^2_2$ 전자구조를 갖는 일그러진 판면체 $[V(III)A_3B_3]$형태 착물의 자기모멘트와 쌍극자모멘트 및 편극율에 대한 $^3T_1$항의 기여분 [A 와 B = O, Cl, N 또는 Br])

  • Sangwoon Ahn;Se Woung Oh;Kee Hag Lee;Eu Suh Park
    • Journal of the Korean Chemical Society
    • /
    • v.24 no.4
    • /
    • pp.269-279
    • /
    • 1980
  • A method for calulation of the magnetic moments for both octahedral and distorted octahedral $[V(III)A_3B_3]$ type complexes, all with $t^2_2$ configuration, has been developed [A and B = O, Cl, N, F or Br]. The calculated magnetic moments by this method are in reasonable agreements with the experimental values. The calculated magnetic moments for distorted octahedral $[V(III)A_3B_3]$/TEX> type complexes decrease as the extent of tetragonal distortion increases.The effects of k (orbital reduction faction factor), $\xi'$/TEX> and temperature on the magnetic moments are also investigated.A new method for calculation of the contribution of $^3T_1$ molecular orbitals to the dipole moment and polarizability has also developed. The calculated contribution of $^3T_1$ molecular orbitals falls in the reasonable range of values.

  • PDF

Synthesis of 6-Hydroxyalkylidenepenicillanates (6-히드록시알킬리덴페니실란산 염의 합성)

  • Lee, Jung Hwan;Ko, Jae Young;Seo, Kyung Jae;Goo, Yang Mo;Lee, Youn Young
    • Journal of the Korean Chemical Society
    • /
    • v.43 no.4
    • /
    • pp.447-455
    • /
    • 1999
  • Allyl (5R)-(Z)- and (5R)-(E)-6-[(2S)-2,3-isopropylidenedioxypropylidene]Penicillanate(10a and 10b) were prepared from allyl (5R)-dibromopenicillanate(6) via a sequence of reactions involving condensation with 2,3-O-isopropylidene-D-glyceraldehyde, reduction with $Zn-NH_4OAc$, and Mitsunobu elimination. Deprotection of isopropylidene and allyl groups of 10a gave potassium (5R)-(Z)-6-[(2S)-2,3-dihydroxypropylidene]penicillanate(4). However, deprotection of isopropylidene group of 10b afforded ${\alpha},\;{\beta}$-unsaturated-lactone(12). Allyl (5R)-(Z)- and (5R)-(E)-6-[(2S)-2-(t-butyldimethlsilyloxy)propylidene]penicillanate(18a and 18b) were prepared from ally (5R)-dibromopenicillanate(6) via a sequence of reactions involving condensation with (2S)-2-(t-butyldimethylsilyloxy)propanal(15), reduction with $Zn-NH_4OAc$ and Mitsunobu elimination or mesylation-elimination. Deprotection of t-butyldimethylsilyl and allyl groups of 18a and 18b gave potassium (5R)-(Z)- and (5R)-(E)-6-[(2S)-2-hydroxypropylidene]penicillanate(5a and 5b), respectively.

  • PDF

A study on the OAM evaluation model for power telecommunications system (전력통신시스템 신뢰도 평가모델 구성 연구)

  • Lee, W.T.;Lee, J.J.;Kim, K.H.;Oh, M.T.;Lee, B.K.;Lee, W.B.
    • Proceedings of the KIEE Conference
    • /
    • 1996.07b
    • /
    • pp.1330-1332
    • /
    • 1996
  • Power telecommunication networks is being increased rapidly in that expansion of power plant according to the growth of electric power supply. The requirement of power plant operation & office automation make it to complex and confusing to operate. So, for the sake of correspond to the change, it is necessary that telecommunication network should be high reliable and managed effectively. In this paper, we suggest total reliability evaluation models for power telecommunication network which is based on the QOS(quality of service) standardization techniques recommanded by ITU-T.

  • PDF

Magnetization Switching of MTJs with CoFeSiB/Ru/CoFeSiB Free Layers (CoFeSiB/Ru/CoFeSiB 자유층을 갖는 자기터널 접합의 스위칭 자기장)

  • Lee, S.Y.;Lee, S.W.;Rhee, J.R.
    • Journal of the Korean Magnetics Society
    • /
    • v.17 no.3
    • /
    • pp.124-127
    • /
    • 2007
  • Magnetic tunnel junctions (MTJs), which consisted of amorphous CoFeSiB layers, were investigated. The CoFeSiB layers were used to substitute for the traditionally used CoFe and/or NiFe layers with an emphasis given on understanding the effect of the amorphous free layer on the switching characteristics of the MTJs. CoFeSiB has a lower saturation magnetization ($M_s\;:\;560\;emu/cm^3$) and a higher anisotropy constant ($K_u\;:\;2800\;erg/cm^3$) than CoFe and NiFe, respectively. An exchange coupling energy ($J_{ex}$) of $-0.003\;erg/cm^2$ was observed by inserting a 1.0 nm Ru layer in between CoFeSiB layers. In the Si/$SiO_2$/Ta 45/Ru 9.5/IrMn 10/CoFe 7/$AlO_x$/CoFeSiB 7 or CoFeSiB (t)/Ru 1.0/CoFeSiB (7-t)/Ru 60 (in nm) MTJs structure, it was found that the size dependence of the switching field originated in the lower $J_{ex}$ using the experimental and simulation results. The CoFeSiB synthetic antiferromagnet structures were proved to be beneficial for the switching characteristics such as reducing the coercivity ($H_c$) and increasing the sensitivity in micrometer size, even in submicrometer sized elements.

Effects of Jeonglyukdaejosapaetang on the Pulmonary Edema of the Rats Induced by the Herbicide, Paraquat (정역대조사폐탕(大棗瀉肺湯)이 Paraquat로 유발(誘發)시킨 흰쥐의 폐수종(肺水腫)에 미치는 영향(影響))

  • Kang Byung-Ku;Lee Si-Hyeong
    • Herbal Formula Science
    • /
    • v.8 no.1
    • /
    • pp.225-239
    • /
    • 2000
  • Pulmonary edema is a disease involving the principal symptoms: dyspnea, bloody phlegm, asthma, cough, etc. According to oriental medical references, Jeomglyukdaejosapaetang (J.D.T) was efficacious for dropsy, cough, dysnea, etc, so it was thought to be used for remedy of pulmonary edema. Therefore experimental study was performed to investigate the effects of J.C.T on pulmonary edema of the rats induced by the herbicide, paraquat.Thus the survival rats, respiratory rats, lung weights and histopathological view of the lungs of rats were studied. The results are as follows. 1. The survival rates at 72hours of the rats injected with paraquat and treated with J.D.T increased in B group(J.D.T + Cortex Lycii Radicis + Cortex mori). The others were not different with the control. 2. The respiratory rates of the rats which survived 72hours later significantly decreased in B group(J.D.T + Cortex Lycii Radicis + Cortex mori). 3. The lung weights of the rats which survived for 72hours later significantly decreased in B group(J.B.T + Cortex Lycii Radicis + Cortex mori). 4. The histopathological views of the lungs of rats induced by paraquat were seen severe hemorrhage, edema and some broken alveoli in control group. But B group(J.D.T + Cortex Lycii Radicis + Cortex mori) were seen little hemorrhage and interstitial hyperplasia. According to the above results, J.D.T + Cortex Lycii Radicis + Cortex mort is effective on the remedy for pulmonary edema of rats induced by paraquat.

  • PDF

New Material for a Super Resolution Disc

  • Kwak, Keum-Cheol;Kim, Sun-Hee;Lee, Chang-Ho;Song, Ki-Chang
    • Transactions of the Society of Information Storage Systems
    • /
    • v.3 no.2
    • /
    • pp.54-58
    • /
    • 2007
  • Using metal/Si materials as a recording layer, we have achieved good results for a SR disc (super resolution disc). Mainly by controlling metal composition and the ratio of metal to Si of recording layer, signal qualities were greatly enhanced. At the mark length of 75nm, the best CNR (Carrier to Noise Ratio) was about 45dB. Write power was reduced down to about 6.5mW. LFN (Low Frequency Noise) could also be reduced down to 14dB. Single tone pattern jitters for every mark whose length is from 2T through 8T were achieved to be below 10%. The readout signal was stable sustaining CNR>40dB during about 15,000 times reading. The so-called "3T-problem" could be avoided.

  • PDF

Computational Study of the Molecular Structure, Vibrational Spectra and Energetics of the OIO Cation

  • Lee, Sang-Yeon
    • Bulletin of the Korean Chemical Society
    • /
    • v.25 no.12
    • /
    • pp.1855-1858
    • /
    • 2004
  • Molecular geometries for the cationic and neutral species of OXO (X=Cl, Br, and I) are optimized using the Hartree-Fock (HF) theory, the second order Moller-Plesset perturbation theory (MP2), the density functional theory with the B3LYP hybrid functional (B3LYP), and the coupled cluster theory using single and double excitation with a perturbational treatment of triplet excitation (CCSD[T]) methods, with two basis sets of triple zeta plus polarization quality. The single point calculations for these species are performed at the CCSD(T,Full) level. The harmonic vibrational frequencies for these species are calculated at the HF, MP2, B3LYP and CCSD(T) levels. The adiabatic ionization potential for OIO is calculated to be 936.7 kJ/mol at the CCSD(T,Full) level and the correct value is estimated to be around 945.4 kJ/mol.