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M-type Sr-Hexaferrite에서 MnCO<sub>3</sub> 첨가에 따른 소결 거동
정민석,유창재,조중영,문경석,Jeong, MinSeok,You, Changjae,Cho, Jung Young,Moon, Kyoung-Seok 한국분말야금학회 2020 한국분말재료학회지 (KPMI) Vol.27 No.2
The grain growth behavior of M-type Sr hexaferrite (SrM) grains is investigated with the addition of MnCO<sub>3</sub>. First, the SrM powder is synthesized by a conventional solid-state reaction. The powder compacts of SrM are sintered at 1250℃ for 2 h with various amounts of MnCO<sub>3</sub> (0, 0.5, 1.0, and 4.0 mol%). There is no secondary solid phase in any of the sintered samples. Relative density increases when MnCO<sub>3</sub> is added to the SrM. Obvious abnormal grain growth does not appear in any of the SrM samples with MnCO<sub>3</sub>. The average grain size increases when 0.5 mol% MnCO<sub>3</sub> is added to the SrM. However, as the amount of MnCO<sub>3</sub> increase to over 0.5 mol%, the average grain size decreases. These observations allow us to conclude that the growth of SrM grains is governed by the two-dimensional nucleation grain growth mechanism, and the critical driving force for the growth of a grain decreases as the amount of MnCO<sub>3</sub> increases.
손우람(Wooram Son),정민석(Minseok Jung),안주영(JooYoung An),윤경로(Kyoungro Yoon) 한국정보과학회 2006 한국정보과학회 학술발표논문집 Vol.33 No.1
저장매체의 대용량화와 인터넷을 이용한 디지털 음원의 활성화로 개인이 소유하는 음원이 급속도로 증가하고 있다. 많은 양의 음원을 보유하고 있는 상황에서 사용자의 편의를 증가시키기 위하여 다양한 검색/분류 방법들이 개발되고 사용되고 있다. 본 논문에서는 음원에 사용된 표현방식이나 디렉토리 구조, 파일이름, 텍스트 태그 등에 독립적으로 적용될 수 있도록 디지털 신호처리 이론에 기반하여 파형데이터를 분석하고, 화성학 이론에 기반한 패턴매칭 기술을 응용하여 음악의 장르와 나아가 분위기를 기반으로 분류하는 방법을 제시한다.
하준범,구가람,정철웅,설한신,정홍석,정민석,Ha, Junbeom,Ku, Garam,Cheong, Cheolung,Seol, Hanshin,Jeong, Hongseok,Jung, Minseok 한국음향학회 2022 韓國音響學會誌 Vol.41 No.3
In this study, each component of flow noise source of underwater propeller installed to the scale model of the KVLCC2 is investigated and the effect of each noise source on underwater-radiated noise is quantitatively analyzed. The computation domain is set to be the same as the test section of the large cavitation tunnel in the Korea Research Institute of Ship and Ocean Engineering. First, for the high-resolution computation of flow field which is noise source region, the incompressible multiphase Delayed Detached Eddy Simulation is performed. Based on flow simulation results, the Ffowcs Williams and Hawkings integral equation is used to predict underwater-radiated noise and its validity is confirmed through the comparison with the tunnel experiment result. For the quantitative comparison on the contribution of each noise source, the spectral levels of sound pressure and power levels predicted using propeller tip-vortex cavitation, blade surface and rudder surface as the integral region of noise sources are investigated. It is confirmed that the cavitation which is monopole noise source significantly contributed to the underwater-radiated noise than propeller blades and rudder which is dipole noise source, and the rudder have more contribution than propeller blades due to the influence of the propeller wake.