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WebRTC 기반 화상회의 시스템의 가상 배경에 딥 러닝 적용에 대한 성능 분석
유상우(Sangwoo Ryu),고경찬(Kyungchan Ko),홍원기(James Won-Ki Hong) 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.6
최근 다양한 서비스에서 인공지능이 활용되고 있고, 영상회의 시스템에서 또한 더 나은 성능을 위해 화질 개선 및 가상 배경 등과 같은 기능에 인공지능을 적용하고 있다. 하지만 웹 기반 영상회의에서는 웹브라우저라는 제한적인 환경으로 인해 이런 기능들의 적용이 제한된다. 본 논문에서는 웹 기반 서비스에서 딥 러닝 모델을 사용하는 기능을 제공하기 위해 웹 환경에 딥 러닝을 적용하는 여러 방식을 소개하고, 실제 영상회의 서비스에 여러 딥 러닝 모델을 적용해 성능을 평가한다. 마지막으로 웹 기반 영상회의에 딥 러닝 모델을 적용하기 위해 고려해야 하는 부분을 논의한다.
FDS를 이용한 실내화재 모사의 문제점 : Ⅱ. 벽면형 및 모서리형 화재 Ⅱ. wall fire and corner fire
고경찬,박외철 한국안전학회 2004 한국안전학회지 Vol.19 No.3
To confirm the previous finding that FDS predicts a fire growth rate too rapid compared with an experiment in a center fire in a room with an opening, the same computational fluid dynamics was applied to two types of fires, wall fire and comer fire. First the grid size was chosen to eliminate possible numerical errors due to a coarse grid system. Then the two types of fires were simulated for three different fire sizes, 7.65, 21.25, and 51.57kW for each type, which are the same as in the experiment to be compared with. The fires were predicted to grow too fast although the average temperatures and heights of the neutral planes were in good agreement with measurement.
FDS를 이용한 실내화재 모사의 문제점 : Ⅰ. 중심형 화재 Ⅰ. Center Fire
고경찬,박외철 한국안전학회 2004 한국안전학회지 Vol.19 No.1
The Fire Dynamics Simulator (FDS) was applied to a center fire in a room, of which dimensions were 1.8m x 1.8m x 1.38m with an opening of 0.45m x 1.2m doorway, to evaluate the numerical method The time-variation of temperature at a top point of the doorway centerline and distributions of average temperature along the doorway centerline and comer stack were compared with measurements for three different fire sizes, 7.65, 21.25 and 51.71M. The results showed FDS predicted a very rapid fire growth compared with the experiment for all the three fire sizes, that is an importand shortcoming of FDS in compartment fire simulations. The average temperature distributions, and heights of hot gas layers and neutral planes in steady state were in reasonable agreement with the measurements.
실내화재에 있어서의 대류열전달에 관한 수치연구 : 1. 수치법 검증과 자연대류 1. Evaluation of Numerical Method and Natural Convection
박외철,고경찬 한국산업안전학회 1999 한국안전학회지 Vol.14 No.2
In a compartment fire, convective heat transfer dominates spread of the fire and smoke movement before flash-over occurs, and natural convection is very important in particular when there are no openings. The finite volume method with SIMPLE algorithm was applied to a square cavity similar to a compartment without an opening. The objectives of this study are to evaluate the method and to simulate natural convection from a hot body in the cavity. The results without the hot body showed an excellent agreement with those of previous studies. Streamlines, isotherms and Nusselt numbers were computed for different Rayleigh numbers.
실내화재에 있어서의 대류열전달에 관한 수치연구(2) : 혼합대류 Mixed Convection
박외철,고경찬,이광진 한국산업안전학회 1999 한국안전학회지 Vol.14 No.3
In a compartment fire with openings, convective heat transfer consists of natural convection from the hot bodies and forced convection by airflow through the openings. The same finite volume method that was applied to pure natural convection in part I was utilized without modification to the square cavity with two openings. The objective of this study is to investigate effects of the openings on temperature distribution. Flow patterns, temperature distribution and heat transfer were compared for different Rayleigh numbers and with and without the openings.
박외철,고경찬 한국산업안전학회 2002 한국안전학회지 Vol.17 No.4
Nonpremixed counterflow flames at low strain rates, ag= 12 s^-1, were numerically simulated to investigate the effects of the duct thickness on the flame structure in normal gravity. For small values of the duct thickness, the positions of the flame and stagnation point were highly sensitive to the duct thickness. When the duct thickness was greater than 6 ㎜, however, the effects of the duct thickness on the flame structure were negligible. The computed temperature along the duct centerline agreed well with measurements.