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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.
여성의원은 여성을 대표하는가? 제19대 국회 여성법안 발의를 중심으로
정민석 ( Jeong Minseok ),이현우 ( Lee Hyeon-woo ) 한국의회발전연구회 2020 의정연구 Vol.26 No.1
제17대 국회에 비례대표 후보 여성할당제가 도입된 이후로, 국회 내 여성의원의 수는 지속적으로 증가해 왔다. 본 연구는 비례대표 여성할당제가 제도적 효과를 달성하고 있는지, 즉 국회에서의 여성의 기술적 대표성 증대가 실질적 대표성의 증대로 이어지는가를 확인하기 위해 제19대 국회의원을 대상으로 여성법안 발의에 있어서 남녀의원의 성차를 분석했다. 분석 결과, 지역구 의원의 경우 여성의원이 남성의원에 비해 여성법안을 통계적으로 유의미하게 많이 발의하는 것으로 나타났다. 그러나 비례대표 의원의 경우에는 남녀의원의 성차가 통계적 유의미성을 띠지 않았다. 이에 따라 본 연구는 비례대표 의원 내에서 기술적 대표성이 실질적 대표성으로 이어지지 않는 현상을 극복하기 위해, 비례대표 후보 여성할당제를 넘어서 지역구에서 선출된 여성의원이 많아지도록 정당의 역할과 함께 제도 개선이 요구된다는 함의를 제공한다. Since gender quota was adopted in the 17<sup>th</sup> National Assembly (2004), the number of women in Korean legislative branch has been increasing constantly. This study analyses the influence of representatives’ gender differences on proposing gender bills to measure the effectiveness of gender quota, in other word, link between descriptive and substantive representation. As a result, among the district representatives, female legislators introduce statistically significantly more gender bills than male representatives. However, in case of proportional representatives, there are no statistically significant difference between female and male legislatives. Consequently, this study implies that political parties’ effort to make more female district representatives are required to overcome the disconnection between descriptive and substantive representation in proportional representatives, beyond gender quota.
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.