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고체 입자가 부상된 충돌제트에서의 입자 거동에 관한 수치해석적 연구
이재범,서영섭,이정희,최영기,Lee, Jae-Beom,Seo, Yeong-Seop,Lee, Jeong-Hui,Choe, Yeong-Gi 대한기계학회 2001 大韓機械學會論文集B Vol.25 No.12
The purpose of this study is to analyze numerically the movement of particles included in turbulent fluid flow characteristics of metallic surfaces. To describe fluid flew, the incompressible Navier-Stokes equation discretized by the finite volume method were solved on the non-orthogonal coordinates with non-staggered variable arrangement, and the k-$\xi$ turbulence model was adapted. After fluid flow was calculated, particle movement was predicted from the Lagrangian approaches. Non-essential complexities were avoided by assuming that the particles had spherical shapes and the Stoke's drag formula only consisted of external farces acting upon them. In order to validate the numerical calculations, the results were compared with the experimental data reported in literature and agreed well with them. The drag force coefficient equation showed better agreement with the experimental data in the prediction of particle movement than the correction factor equation. Impact velocity and impact angle increased as inlet turbulence intensity decreased, relative jet height was lower. or the Reynolds number was larger.
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The Meaning of Healthy Pleasure and Healthy Aging in Korean Society
이재범 사단법인 한국융합기술연구학회 2025 아시아태평양융합연구교류논문지 Vol.11 No.5
Korean society's low birth rate and aging induce social and economic changes at the national level and are accompanied by psychological, physical, and living environment changes at the individual level. Accordingly, this study was conducted to understand the meaning of healthy pleasure and healthy aging in Korean society and to determine the direction in which the response strategy is moving. The data collection method used to achieve this purpose was a face validity verification method that assigns meaning centered on topic elements. The data analysis method used was to code the literature selected for analysis to a certain range and use the inter-rater agreement method for the data and analysis results that fit the research content. The data used in this study were mainly KCI research papers related to healthy aging and pleasure published in Korea over the past 15 years, online data from Korea's 2024 National Statistical Office social survey, population change trends announced by the Ministry of Health and Welfare, and data and policies from joint meetings of related ministries. In Korea, after the COVID-19 pandemic, everyone has become aware of the importance of health that touches their skin. Therefore, healthy pleasure and healthy aging are not separate concepts but exist in an institutional and personal continuum and should be interpreted as concepts of strengthening inherent capabilities and sustainability. Healthy and successful aging are everyone’s hopes for their future selves. Currently, in Korea, the trend of healthy pleasure and aging is changing from treatment to prevention and is changing into the starting and ending points of self-management.
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철도차량용 경량·고효율 배터리 충전기를 위한 전력변환회로 연구
이재범,정신명,조인호,송민섭 한국철도학회 2018 한국철도학회논문집 Vol.21 No.11
In order to achieve design freedom and reduce carbon emissions, various studies have recently been implementedfor lightweight and high-efficiency power conversion devices in the railway system. Especially, next generationsemiconductor devices can be applied to the auxiliary power system at a relatively low price, because the rated powercapacity is lower than that of the propulsion power system. However, light weight and high efficiency have almost beenachieved by changing the isolation method among the pantograph source, three-phase load, and battery load. In thispaper, in order to lighten the 10kW modular battery charger in the railway system, the sizes of the transformer, outputinductor, and output capacitor are reduced with high driving frequency. Moreover, in order to achieve high efficiencydespite high driving frequency, low-power SiC power semiconductor devices instead of conventional Si power semiconductordevices are applied, and highly efficient optimal topologies with SiC power semiconductor devices are investigated.
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