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[열유체부문] 일래스토메릭 부싱의 축방향모드의 점탄성모델연구
류재하(Jae Ha Ryu),류재평(Jae Pyoung Ryu),이성범(Seong Beom Lee) 한국자동차공학회 2001 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2001 No.11_1
An elastomeric bushing is a device used in automotive suspension systems to cushion the force transmitted from the wheel to the frame of the vehicle. A bushing is an elastomeric hollow cylinder which is bonded to a solid metal shaft at its inner surface and a metal sleeve at its outer surface. The relation between the force applied to the shaft or sleeve and their relative deformation is nonlinear and exhibits features of viscoelasticity.<br/> The new nonlinear viscoelastic bushing model. which is called Pipkin-Rogers model, is proposed and it is compared with Applied mechanics model, which is called Lianis model. The results of Pipkin-Rogers model is in very good agreement with that of Lianis model.<br/>
류재하(Jae Ha Ryu),은진희(Jin Hee Eun),이소영(So Young Lee),장준식(Joon Shik Chang),박만기(Man Ki Park),박정일(Jeong Hill Park),한용남(Yong Nam Han),한병훈(Byung Hoon Han) 大韓藥學會 1997 약학회지 Vol.41 No.5
Two alkaloidal components were isolated from the ether soluble part of the MeOH extract of the root bark of Euonymus japonica. Their structures were elucidated by the spectroscopic analylses as the sesquiterpene pyridine alkaloids derived from polyester sesquiterpenes which are characteristically detected in Celastraceae plants. These include macrocycle formed by two ester linkages between dihydro-beta-agarofuran nucleus and pyridinic dibasic acid(compound 1:evoninic acid, compound 2:wilfordic acid). The structure of compound 1[C47H50N2017, mp 161~163oC. [alpha]D28=+31.6o(c, 0.1 in EtOH)] was determined as novel structure named as euojaponine N, and compound 2[C48H57NO18, mp 142~145oC, [alpha]D27=+27.0o(c, 0.1 in EtOH)] was identified as ebenifoline W-I reported from Maytenus ebenifolia.
이화진,류재하,Lee, Hwa-Jin,Ryu, Jae-Ha 한국생약학회 2000 생약학회지 Vol.31 No.3
Leukotriene $B_4\;(LTB_4)$ is a pro-inflammatory mediator synthesized in myeloid cells from arachidonic acid. Elevated levels of $LTB_4$ have been found in a number of inflammatory diseases and levels are related to disease activity in some of these. Because $LTB_4$ interacts with cells through specific cell surface receptors, $LTB_4$ receptor blockade is the most specific approach to reduce the pathogenic role of $LTB_4$. In order to find $LTB_4$ receptor antagonist from plants, we screened the $LTB_4$ receptor antagonistic activity of the methanol extract and solvent fractions of herbal drugs. The ability of samples to inhibit specific binding of $[^3H]-LTB_4$ to human peripheral neutrophils was used as assay to evaluate the antagonistic activity of plant materials. Among the tested methanol extracts of herbal drugs, Mori Radicis Cortex, Perillae Semen, Armeniacae Semen and Sophorae subprostratae Radix showed potent inhibitory activity above 70% at the concentration of $100\;{mu}g/ml$. The inhibitory activities of $LTB_4$ binding to human neutrophils were evaluated for several solvent fractions at three different concentrations. Especially, hexane soluble fractions of Anemarrhenae Rhizoma and Embeliae Radix, and ethyl acetate soluble fractions of Aristolochiae Fructus, Magnoliae Cortex and Zingiberis Rhizoma crudus showed moderate activity at $25\;{mu}g/ml$. These fractions were promising candidates for the study of the activity-guided chromatographic purification of active compounds. Silica gel column chromatography of hexane soluble fractions of Anemarrhenae Rhizoma and Embeliae Radix gave very active sub-fractions, AA-4 and ES-4, and their inhibition activities of $LTB_4$ binding to human neutrophil at $30\;{mu}g/ml$ were 78% and 62%, respectively. From these results we could anticipate new $LTB_4$ receptor antagonist from herbal drugs, and the block of $LTB_4$ effects may provide beneficial in neutrophil mediated diseases such as inflammation and bronchial asthma.
이종임,진창배,류재하,조정숙,Lee, Jong-Im,Jin, Chang-Bae,Ryu, Jae-Ha,Cho, Jung-Sook 대한약학회 2008 약학회지 Vol.52 No.2
The leaves of Perilla frutescens Britt. var. japonica Hara (Labiatae) are often used in gourmet food in several Asian countries. Two kinds of perilla cultivars, Namcheon (NC) and Bora (BR), have been respectively developed in Korea by the pure line of 'deulkkae' from the local variety and by the cross of 'deulkkae' and 'chajogi'. The present study evaluated and compared antioxidant and neuroprotective effects of the fractions prepared from the leaves of the two cultivars using cell-free bioassay systems and primary cultured rat cortical cells. We found that the spirit, chloroform, hexane and butanol fractions from NC and BR leaves inhibited lipid peroxidation initiated in rat brain homogenates by $Fe^{2+}$ and L-ascorbic acid. In contrast, only the spirit and butanol fractions from both cultivars exhibited 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity. Among the fractions tested, the butanol fractions from NC and BR leaves exhibited the most potent antioxidant properties, and the butanol fraction from BR was more potent than the NC fraction. In consistence with these findings, the butanol fractions from both cultivars protected primary cultured cortical cells from the oxidative damage induced by $H_2O_2$ or xanthine and xanthine oxidase, with the BR butanol fraction being more active. The butanol fractions from NC and BR did not produce cytotoxicity in our cultures treated for 24 h at the concentrations of up to $100\;{\mu}g/ml$. Taken together, these results indicate that the leaves of the two cultivars of Perilla frutescens exert antioxidant and neuroprotective effects, and that the butanol fraction from BR leaves exhibits the most potent antioxidative neuroprotection among the fractions tested in this study.
가스크로마토그라피에 의한 아미노산 광학이성체의 분리 I 광학활성 N-Benzoyl-L-Valine 유도체의 고정상으로의 응용
박만기(Man Ki Park),류재하(Jae Ha Ryu),강종성(Jong Seong Kang) 대한약학회 1985 약학회지 Vol.29 No.6
The gas chromatographic behavior of optically active N-(N-benzoyl-L-valyl)-anilide used as stationary phase is described. N-(N-benzoyl-L-valyl)-anilide has been synthesized with good yield under mild condition via Schotten-Bauman process and coated on the Chromosorb W AW (80~100 mesh) for the purpose of enantiomer separation. The behavior of this compound as optically active stationary phase for the separation of the enantiomers of N-TFA-D, L-amino acid isopropyl esters has been examined with respect to the correlation between the separation factors and column temperatures. All amino acid enantiomers examined were eluted within one hour and the elution pattern showed retention times increasing in the order of alanine, valine, leucine, threonine, proline and methionine.