• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.299-302
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• 2006

본 논문에서는 다중필터와 복합형 신경망으로 구성된 얼굴 검출 시스템과 WFMM 신경망을 이용한 피부색 검출기법을 소개한다. 전처리 단계에 해당하는 다중필터는 대상 영역의 수를 감소 시켜 시스템의 속도를 개선한다. 다중필터에 속한 색상필터는 총 11 가지의 색상 공간에서 피부색의 특징 값을 추출하여 학습 데이터로 사용하며, 이 학습 데이터에 의해 생성된 하이퍼 박스를 통해 피부색을 분류한다. 또한 WFMM 신경망의 연관도 요소 특성을 이용하여 각 색상 공간의 상대적 중요도를 분석하여 피부색 검출에 유용한 색상 공간을 분석하고 추출 한다. 얼굴패턴 검출을 위한 복합형 신경망은 첫 단계에서 가보 변환을 사용하는 CNN 을 통해 특징 지도를 생성하고, WFMM 신경망으로 최종 얼굴패턴을 검증한다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.12
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• pp.1674-1680
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• 2002

An experimental study was made of a large-scale vortical structure over a backward-facing step. The Reynolds number based on the step height was R $e_{H}$ =33,000. To recognize the large-scale vortex, three components of velocity were measured. The measurements were performed in the recirculation zone (x/H=4.0) and the reattachment zone(x/H=7.5). To measure the wall pressure fluctuations in a turbulent flow over a backward-facing step, a 32-channel microphone array was installed beneath the wall in the streamwise and spanwise directions. From the measured pressure field, the size of large-scale vortex was obtained. As a detailed study, a conditionally-averaging technique was employed to characterize the coherent structure of the large-scale vortex. To see the relationship between the flow field and the relevant spatial mode of the pressure field, the spatial box filtering (SBF) was examined. A cross-correlation between velocity and pressure fluctuations was performed to identify the structure and the length scale of the large-scale vortex.x.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.12
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• pp.1708-1715
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• 2003

An experimental study was made of turbulent separated and reattaching flow over a backward-facing step, where unsteady wake was generated by a spoked-wheel type wake generator with cylindrical rods in front of the separated flow. The influence of unsteady wake was scrutinized in terms of the rotating speed of the wake generator (0$\leq$S $t_{H}$$\leq$0.4). A conditional averaging technique in corporation with SBF was employed to elucidate the influence of the unsteady wake on the large-scale vortical structures of the separated flow. Special attention was made during two-dimensional measurements of wall-pressure with or without unsteady wake. The wall-pressure fluctuations were used to predict dipole sound source by Curie's integral formula. It was found that the reduction of the dipole sound source was due to the reduction of turbulent kinetic energy by unsteady wake in the recirculation region.n.