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김진구,최정일,장대수,나종태,김용억 한국수산과학회 2003 한국수산과학회지 Vol.36 No.5
Distribution of ichthyoplanktons and its relation to environmental factors (temperature, salinity, $chlorophyll\;\alpha$) around the Youngsan River Estuary of Mokpo, southwest coast of Korea were investigated based on the samples collected bimonthly from February to December, 2001. Unidentified fish eggs were most abundant $1,345\;eggs/100m^3$ in August, while eggs of Engraulis japonicus were most abundant $63\;eggs/100m^3$ in June. A total of forty species of fish larvae and juveniles belonging to the twenty families under six orders were caught, with six gobiids, four icefishes, four croakers and three herrings being represented. Fish larvae and juveniles peaked $17,757\;inds./100m^3$ in August, which consisted of $91.02\%$ of gobiids, $3.69\%$ of gunnels and $3.67\%$ of icefishes, and they were most abundant $7,467\;Inds./100m^3$ at St. 7. Cluster analysis based on the individuals of fish larvae and juveniles showed that six months were classified into two groups at the dissimilarity 70, the first was composed of June and August and the second was February and December and April and October were not clustered with any other months. In August when species diversity index was the highest, eight stations were classified into two groups at the dissimilarity 70, the first was composed of St. 1, 3, 4, 5 and 8 and the second was St. 6, 7 and 2. As a result from correspondence analysis, there is no effect of the environmental factors with a density of fish eggs and larvae, but correlation could be found between a density of fish eggs and $chlorophyll\;\alpha.$
유연 패드가 장착된 브레이크 시스템 대상 제동 스퀼 관련 주요 인자의 영향 연구
이은석,김관주,유남식,이범주,나선주,나종태 한국정밀공학회 2022 한국정밀공학회지 Vol.39 No.5
The brake squeal noise is a high-frequency noise over 1 kHz range generated by the contact between the brake pad and the disk. The purpose of this paper was to investigate the behavior of the squeal noise characteristics of the brake system from an instability point of view, according to the variation of major parameters such as friction coefficient between the flexible pad and the disk, brake pressure, and Young’s modulus of disk. Full nonlinear perturbed modal analysis using commercial finite element analysis program was performed to derive complex eigenvalue results of the model. And the sensitivity behavior was observed. Increasing the coefficient of friction or Young’s modulus of disk tended to make the squeal mode of the model more unstable. However, the change in brake pressure has a complicated nonlinear relationship with the squeal mode of the model. The judgment technique conducted in this study should be considered to be used in the design of the vibration point of the disk and pad of railway vehicles in the future.
한국형 틸팅열차용 Flexible 소결 브레이크 패드 적용 연구
구성모(Seong-Mo Ku),이동균(Dong-Kyun Lee),고태환(Tae-Hwan Ko),나종태(Jong-Tae Na),김상호(Sang-Ho Kim) 한국철도학회 2010 한국철도학회 학술발표대회논문집 Vol.2010 No.7
Metallic sintered brake pads are often applied to Mid/High Speed Train due to its high strength and thermal characteristics. Because of its imbalance contact between discs and pads can greatly influence the life span, one sided wear, discs attack/crack and threat the safety of the train during operation. In this research, we analyzed pressure/temperature distribution between brake pads and disks. Analyzed data had been verified and modified to conduct further tests of Flexible brake pads with small/full-scale dynamo test. Flexible brake pads were installed to TTX train to conduct further tests to identify the differences between Rigid brake pads and Flexible brake pads. In result, Flexible brake pads showed outstanding disk thermal stability, one sided wear, noise and life of pad than rigid brake pad.
이은석(Eunseok Lee),김관주(Kwanju Kim),유남식(Namsik Yoo),이범주(Beomjoo Lee),나선주(Sunjoo Na),나종태(Jongtae Na) Korean Society for Precision Engineering 2022 한국정밀공학회지 Vol.39 No.5
The brake squeal noise is a high-frequency noise over 1 kHz range generated by the contact between the brake pad and the disk. The purpose of this paper was to investigate the behavior of the squeal noise characteristics of the brake system from an instability point of view, according to the variation of major parameters such as friction coefficient between the flexible pad and the disk, brake pressure, and Young’s modulus of disk. Full nonlinear perturbed modal analysis using commercial finite element analysis program was performed to derive complex eigenvalue results of the model. And the sensitivity behavior was observed. Increasing the coefficient of friction or Young’s modulus of disk tended to make the squeal mode of the model more unstable. However, the change in brake pressure has a complicated nonlinear relationship with the squeal mode of the model. The judgment technique conducted in this study should be considered to be used in the design of the vibration point of the disk and pad of railway vehicles in the future.