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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.
류재하(Jaeha Ryu),김민수(Minsoo Kim),김연중(Yeonjoong Kim),정찬기(Chankee Jung) 한국지반환경공학회 2021 한국지반환경공학회논문집 Vol.22 No.8
연약 점성토 지반에 고속국도 등 대규모 SOC 공사 시 과대한 침하량으로 인하여 많은 문제점들이 발생하고 있어 정확한 침하예측은 개량공법의 선정, 사업비, 사업기간에 많은 영향을 미치게 된다. 현재 설계 시 사용되고 있는 대부분의 침하량 예측기법으로는 연약 점성토 지반의 두께를 단일층으로 하여 1차원 Terzaghi 압밀이론을 적용하고 있다. 그러나 연약 점성토 지반의 침하예측 시 대상층을 다수의 수평층으로 분할할 경우 침하량에 변화가 발생하고 있다. 본 연구에서는 성토고 변화 조건에서 연약점성토지반 수평분할에 따른 압밀침하거동을 분석하였다. In the case of construction on soft ground - such as national expressways sponsored by Social Overhead Capital (SOC) - many problems occur due to excessive settlement: therefore, an accurate settlement prediction has a major impact on the selection of improvement methods, project budget and construction period. Most of the settlement prediction methods currently used in projects apply Terzaghi’s Theory of One-Dimensional Consolidation which assumes the uniformity of the depth of the soft ground. However, the results of soft ground settlement predictions vary when the target layer is divided into multiple horizontal layers. This study analyzed the change in the consolidation settlement behavior according to the horizontal division of soft ground as well as with different loading height.
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.