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철도소음 측정망에 대한 적정한 소음측정방법의 비교 연구
이창혁(Chang Hyeok Lee),노유진(Yu Jin Noh),김인규(In Kyu Kim),이병찬(Byung Chan Lee) 한국소음진동공학회 2019 한국소음진동공학회 논문집 Vol.29 No.6
The railway noise measurement network shows the noise around the railway area by one manual measurement every half year. This method suffers with limitations in determining the railway noise levels. To obtain more reliable measurement data and to obtain basic data for noise reduction procedures, the railway noise was measured for one year at six railway stations in three cities, using a portable automatic sound meter. The noise levels were averaged daily, monthly and annually. Notably, the automatically measured noise levels were lower than those measured manually (-1 to –18 dBA), at all the six stations. Further, the noise levels during the nighttime, due to lower train traffic, were –18 dBA lower than those by manual measurement methods. At all the six stations during the nighttime, the automatically measured noise levels were within the reference range, whereas those measured manually, exceeded. According to the train traffic volume and complaint of the railway noise, either the stationary or portable automatic methods, or the manual methods should be employed for measuring the railway noise.
PAV용 Skid Landing Gear의 설계 민감도에 대한 구조 해석적 연구
이창혁(Chang-Hyeok Lee),문창일(Chang-Il Moon),허장욱(Jang-Wook Hur) 한국기계가공학회 2023 한국기계가공학회지 Vol.22 No.12
In this study, the design sensitivity of the landing gear, a component of the PAV and UAM airframes that are emerging as a new means of transportation in the field of aviation, was structurally analyzed. In the case of eVTOL type PAV and UAM airframes, mass production marketability must be ensured by reducing airframe development and maintenance costs; the skid type landing gear structure can meet this requirement. In this study, a large deformation finite element analysis was performed on a skid landing gear consisting of only an aluminum tube structure without a damper for shock absorption structural integrity was examined stress and displacement owing to design changes of members were analyzed, A trend analysis of design sensitivity was performed.
다변량분석에 의한 여수 백야도 어류양식장의 해양 환경분석
이창혁(Chang-Hyeok LEE),강만구(Man-Gu KANG),임수연(Su-Yeon LIM),김재현(Jae-Hyun KIM),신종암(Jong-Ahm SHIN) 한국수산해양교육학회 2017 水産海洋敎育硏究 Vol.29 No.3
This study was conducted to evaluated the surface(10 variables) and bottom(10 variables) water quality, and sediment(3 variables) in the cage fish farm off Baegyado in Gamak Bay using a multivariate analysis from January 2013 to November 2014. Generally, the environmental data did not show a certain tendency by months during two years investigated. The pairwise simple correlation matrices among variables were also shown. The first four principal components of the surface water in 2013 explain 93% of the total sample variance; the first principal component(z₁) showed the freshwater inflow and/or precipitation, z₂, z₃ and z₄ related to freshwater inflow and/or precipitation, organic matters and eutrophy, respectively; the first four principal components of the bottom water in 2013 explain 93% of the total sample variance; the z₁, z₂ and z₄ related to freshwater inflow and/or precipitation, and z₃ water temperature. In 2014, at the surface water the first three principal components explain 87%; the z₁, z₂ and z₃ related to water temperature, eutrophy and freshwater inflow and/or precipitation, respectively; at the bottom water the first three principal components explain 93%; z₁, z₂ and z₃ related to water temperature, freshwater inflow and/or precipitation and eutrophy. Half of the principal components related to freshwater inflow and/or precipitation.