Search | Korea Science

Forced Vibration Analysis for Duffing's Vibration Systems with the Multi-Degree-of-Freedom Systems (다자유도계를 갖는 듀핑 진동계의 강제진동해석)

전진영;박용남;김정렬;김의간
- Journal of Advanced Marine Engineering and Technology
- /
- v.24 no.1
- /
- pp.18-24
- /
- 2000
As ship's propulsion shafting system has been complicated, many linear methods that have been used until now are not sufficient enough to produce proper solutions and these solutions are ofter unreasonable. So we need to solve nonlinear systems, and many methods for solving nonlinear vibration system have been developed. In this study, the propulsion shafting system was modeled with Duffing's nonlinear vibration system and multi-degree-of-freedom, and analyzed by using Quasi-Newton method. And for the purpose of confirming the reliability of the calculating results for nonlinear forced torsional vibration of the propulsion shafting system, the nonlinear calculated results were compared with the linear calculated ones for ship's propulsion shafting system. In the result, for analysis of the forced torsional vibration of the propulsion systems with nonlinear elements, the modified Newton's method is confirmed reasonable.
PDF

The effects of Mozart's music on metabolic response upon stress

Lee, Sujin;Yoo, Ga Eul;Chong, Hyun Ju;Choi, Seung Hong;Park, Sunghyouk
- Journal of the Korean Magnetic Resonance Society
- /
- v.24 no.1
- /
- pp.23-29
- /
- 2020
Mozart's music has been suggested to affect spatio-temporal reasoning of listeners, which has been called "Mozart effect". However, the effects of Mazart's music on human metabolism have not been known. We dissected Mozart's music into its compositional elements and studied their effects on metabolism of experimental animals. Mozart music significantly reduced cortisol level induced by stress. NMR metabolomic study revealed different urine metabolic profile according to the listening to Mozart's music. In addition, each element of music exhibited different metabolic profile. Functional MRI study also showed enhanced brain activity upon listening to Mozart's music. Taken together, Mozart's music seems to be related with brain activity, stress hormone and whole body metabolism.
https://doi.org/10.6564/JKMRS.2020.24.1.023 인용 PDF KSCI

Comparison of Blood Physiology in Juvenile Black Seabream (Acanthopagrus schlegeli) Reared in Converted Freshwater from Seawater and Seawater from Freshwater (해수사육에서 담수사육으로, 담수사육에서 해수사육으로 전환된 감성돔 치어, Acanthopagrus schlegeli의 혈액생리학적 비교)

Chang Young Jin;Min Byung Hwa;Chang Hae Jin;Hur Jun Wook
- Korean Journal of Fisheries and Aquatic Sciences
- /
- v.35 no.6
- /
- pp.595-600
- /
- 2002
Comparison of blood properties in juvenile black seabream (Acanthopans schlegeli) between transfer from seawater to freshwater (sFW) and transfer from freshwater to seawater (fSW) were investigated for 60 days. Plasma cortisol levels in sFW were significantly increased from 34.2 $\pm$ 28.6 ng/mL at the beginning to 365.6 $\pm$ 136.0 ng/mL at 3 hours, and decreased to the beginning level at 24 hours. However, in fSW, no significant differences in the cortisol levels were recognized throughout experimental period. No significant difference was found in the glucose levels between sFW and fSW. The transfer from seawater to freshwater of juvenile black seabream resulted in reduced $Na^{+}\;and\; Cl^{-}$ concentrations for 24 hours (decreasing from 165.3 $\pm$ 2.5, 146.0$\pm$ 2.2 to 118.3 $\pm$ 12.3, 78.0$\pm$ 7.0 mEq/L, respectively), but these were completely recovered the beginning levels at 30 days. Total protein and AST showed no significant differences between the two rearing conditions, while ALT was markedly elevated at 3 hour in sFW and at 24 hours in fSW. Ht in sFW was increased from 18.5 $\pm$ $0.6\%$ at the beginning to 25.3 $\pm$ $4.0\%$ at 12 hours, and was decreased to the beginning level at 24 hours. Ht, RBC and Hb in fSW were also significantly higher at 12 hours, but recovered to their initial levels at 24 hours. All fish were dead until 50 days in sFW while survival rate in fSW was $85\%$ at the end of experiment.
https://doi.org/10.5657/kfas.2002.35.6.595 인용 PDF KSCI