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남지인(Jiin Nam),박희재(Hee Jae Park) 한국생산제조학회 2020 한국생산제조학회지 Vol.29 No.3
In this study, a fault detection and classification method using neural network-based acoustic measurement is proposed. In this method, a measured acoustic signal of the target equipment undergoes Fast Fourier transformation. The magnitude, for a range of frequencies, is accumulated and normalized to train predefined neural network model. To validate the proposed method, an experimental setup for cooling fan is established. The faults of the device are classified into five categories. A series of experiments for the experimental setup are conducted to validate the performance of the fault detection and classification of the proposed method. An accuracy of up to 98.6% is obtained for the test data. Thus, the experimental results show the effectiveness of the proposed fault detection algorithm.
도시의 가로연결성과 생활성의 관계에 관한 비교연구: 세계 30개 도시의 공간분석을 중심으로
남지인(Nam, Ji In),강명구(Kang, Myoung Gu) 한국지역개발학회 2022 한국지역개발학회 학술대회 Vol.2022 No.5
Street connectivity is one of the pivotal factors for sustainable urban development and mitigation of congestion in a city. Global city indices have been developed to evaluate competitiveness and livability of cities, including sub-indicators related to urban spatial features; sprawl, green space, natural assets, connectivity, public transportation and traffic congestion, etc. However, it is hard to figure out how urban spatial structures are relevant to livability of the cities since these sub-indicators rarely include the street connectivity that is a fundamental element of a city fabric. This study aims to find the relationship between the urban street connectivity and the livability by analyzing spatial patterns of 30 cities around the world. The street density and the intersection density account for the street connectivity. OpenStreetMap (OSM) in QGIS was utilized to extract the road data of each city in this paper. With those data, the street density and the intersection density of the 30 cities were calculated. The result shows that in the city where the street connectivity is high, the livability is also high. This paper has done the empirical spatial analysis focusing on the relationship between the street connectivity and the livability of the cities. Second, the street data of 30 cities was extracted. These datasets will be a valuable primary resources for future research in particular of those cities in developing countries.
지진해일 중 해안안벽 주변의 부유체 거동에 관한 입자법 시뮬레이션
박지인(Ji-In Park),황성철(Sung-Chul Hwang),남정우(Jung-Woo Nam),정세민(Se-min Jeong),박종천(Jong-Chun Park) 대한조선학회 2012 대한조선학회 학술대회자료집 Vol.2012 No.5
Tsunamis are ocean waves generated by movements of earth's crust. Several geophysical events can lead to this kind of catastrophe: earthquakes, landslides, volcano eruptions and other mechanisms such as underwater explosions. Most of the damage associated with tsunamis is related to their wave run-up at the shoreline. Therefore, well prediction of maximum wave run-up is an important aspect of any seismic sea wave mitigation effort. In this study, the numerical simulations of the behaviors of a floating body near quaywall during Tunami are investigated by using a particle method. First, the wave run-up with solitary waves are validated though the comparison with experiments and theoretical formulation. Then the behaviors of a floating body with different draft are investigate numerically.
자유표면 유동해석을 위한 WMLS 기반 입자법 기술 개발
남정우(Jung-Woo Nam),박종천(Jong-Chun Park),박지인(Ji-In Park),황성철(Sung-Chul Hwang),허재경(Jae-Kyung Heo),정세민(Se-Min Jeong) 한국해양공학회 2014 韓國海洋工學會誌 Vol.28 No.2
In general, particle simulation methods such as the MPS(Moving Particle Simulation) or SPH(Smoothed Particle Hydrodynamics) methods have some serious drawbacks for pressure solution. The pressure field shows spurious high fluctuations both temporally and spatially. It is well known that pressure fluctuation primarily occurs because of the numerical approximation of the partial differential operators. The MPS and SPH methods employ a pre-defined kernel function in the approximation of the gradient and Laplacian operators. Because this kernel function is constructed artificially, an accurate solution cannot be guaranteed, especially when the distribution of particles is irregular. In this paper, we propose a particle simulation method based on the moving least-square technique for solving the partial differential operators using a Taylor-series expansion. The developed method was applied to the hydro-static pressure and dam-broken problems to validate it
파랑 중 오일붐 성능 예측을 위한 2차원 입자법 시뮬레이션
남정우(Jung-Woo Nam),박지인(Ji-In Park),황성철(Sung-Chul Hwang),박종천(Jong-Chun Park),정세민(Se-Min Jeong) 한국해양공학회 2013 韓國海洋工學會誌 Vol.27 No.4
Oil booms are one of the most widely used types of equipment for the protection of coastal areas against oil spills. In some situations, however, there are several types of oil leaks from the oil boom. Important factors regarding these phenomena include the surrounding ocean environment, such as waves, the density and viscosity of oil, the length of the oil boom skirt, etc. To estimate the performance of the oil boom, it is necessary to predict the behavior of the spilled oil and oil boom. In the present study, the prediction of oil boom performance in waves was carried out using the Pusan?National?University?modified Moving Particle Semi?implicit (PNU?MPS) method, which is an improved version of the original MPS proposed by Koshizuka and Oka (1996). The governing equations, which consist of continuity and Navier?Stokes equations, are solved by Lagrangian moving particles, and all terms expressed by differential operators in the governing equations are replaced by the particle interaction models based on a kernel function. The simulation results were validated through a comparison with the results of Violeau et al. (2007).
지진해일 중 해안안벽 주변의 부유체 거동에 관한 입자법 시뮬레이션
박지인(Ji-In Park),황성철(Sung-Chul Hwang),남정우(Jung-Woo Nam),정세민(Se-min Jeong),박종천(Jong-Chun Park) 한국해양환경·에너지학회 2012 한국해양환경공학회 학술대회논문집 Vol.2012 No.5
Tsunamis are ocean waves generated by movements of earth"s crust Several geophysical events can lead to Ms kind of catastrophe: earthquakes, landslides, volcano eruptions and other mechanisms such as underwater explosions. Most of the damage associated with tsunamis is related to their wave run-up at the shoreline. Therefore, well prediction of maximum wave run-up is an important aspect of any seismic sea wave mitigation effort. In this study, the numerical simulations of the behaviors of a floating body near quaywall during Tunami are investigated by using a particle method. First, the wave run-up with solitary waves are validated though the comparison with experiments and theoretical formulation. Then the behaviors of a floating body with different draft are investigate numerically.