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高次스펙트럼을 利用한 機關 排氣系의 非線型 脈動壓力 解釋에 관한 硏究
이준서(J.S.Lee),이민호(M.H.Lee),김명균(M.G.Kim),김봉각(B.K.Kim),임인권(I.G.Lim),차경옥(K.O.Cha) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.5_1
The engine exhaust noise is mainly made of the pulsating gas flow and pulsating pressure at a very high pressure level. Frequently, this pulsating pressure level is out of the pressure level range which the linear acoustic theory is applicable. The conventional prediction method which is based on the linear acoustic theory gives an overestimate in comparison with results measured in operating engines. This paper, as the first step for solving this problem, proposes a non linear effect of pulsating pressure waves. The phenomenon proposed here is identified by using of higher order spectrum(bicoherence),<br/>
서로 다른 이온기를 도입한 폴리(에틸 아크릴레이트) 아이오노머 블렌드의 동적·기계적 성질
송주명,박재진,김명균 조선대학교 생산기술연구소 2005 生産技術硏究 Vol.27 No.spec
The miscibility in homoblends of ehtyl acrylate ionomers containing acrylate and itaconate ionic groups was studied dynamic mechanically. It was found that the ionomer blends containing 6 ㏖% of ionic repeat unit showed two cluster Tgs, except for the samples having a very small amount of one component. This implies that these ionomers are more or less immiscible. When the ion content of the acrylate ionomer increased to ca. 12㏖%, however, the cluster Tg of the itaconate ionomer dropped with increasing the amount of acrylate ionomer. It was also found that some of the ionomer blends showed only on cluster Tg. Thus, it was suggested that at high ion contents the chances fot the ionic groups to form ionoic aggregates increase, which, in turn, improved miscibility of the ionomer blends.
플렌드된 Poly(styrene-co-sodium methacylate) 아이오노머와 순수한 아이오노머의 동력학적 성질 비교
송주명,박재진,김명균 조선대학교 생산기술연구소 2005 生産技術硏究 Vol.27 No.spec
The dynamic mechanical properties of poly(styrene-sodium methacrylate) (SMANa) ionomer containing 7.3 ㏖% of ions were compared with those of SMANa ionomer mixtures containing the same amount of ions. It was found that the ionic moduli of the pure ionomer and ionomer mixtures were very similar to each other. This indicates that the mixing process does not change the degree of clustering. However, the slope of ionic plateau became steeper as the difference in the ion contents of two ionomers in an ionomer mixture increased, suggesting that the inhomogeneity of the matrix and cluster phases increased. It was also observed that the difference between the matrix and cluster Tgs increased with increasing divergence of the ion contents of two ionomers in an ionomer mixture. In addition, it was found that when the difference of the two ion contents became ca. 6 ㏖%, the ionomer mixture started to show a trace of a phase-separation. At ca. 9 ㏖%, the ionomer mixture exhibited a third loss tangent peak, Possibly due to the presence of well phase-separated matrix regions. The SAXS study showed that, even though the three-dimensional arrangement of multiplets in an ionomer matrix was not changed upon the mixing of two ionomers, the inhomogeneity of phases increased.