• 한국음향학회지
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• 제43권5호
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• pp.475-483
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• 2024

본 논문은 단일 수신기를 이용하여 음원의 속도 또는 거리를 추정하는 기법의 하나인 음장 차분 기법을 적용할 때 사용하는 신호 처리 파라미터를 검토하고, 파라미터 선정 시 고려해야 하는 구속 조건과 성능에 미치는 효과를 분석하였다. SWellEX-96 해상 실험 데이터를 사용하여 본 연구에서 확인한 여러 사례들은 음장 차분 기법 적용 시 파라미터 설정에 따라 속도 추정 결과에 큰 오류가 발생할 수 있음을 보여준다. 본 연구에서는 신호 주파수에 따라 음장 차분 기법 신호 처리 파라미터의 영향이 달라질 수 있음을 확인하고, 정확한 속도 추정을 위한 음장 차분 기법 파라미터 선정 가이드라인을 제시하였다.

• 한국유체기계학회 논문집
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• 제15권1호
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• pp.27-35
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• 2012

A numerical simulation for particle collection efficiency in a wire-plate electrostatic precipitator (ESP) has been performed. Method of characteristics and finite differencing method (MOC-FDM) were employed to obtain electric field and space charge density, and lattice boltzmann method (LBM) was used to predict the Electrohydrodynamic (EHD) flow according to the ion convection. Large eddy simulation (LES) was considered for turbulent flow and particle simulation was performed by discrete element method (DEM) which considered field charging, electric force, drag force and wall-collision. One way coupling from FDM to LBM was used with small and low density particle assumption. When the charged particle collided with the collecting plate, particle-wall collision was calculated for re-entertainment effect and the effect of gravity force was considered.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2001년도 추계 학술대회논문집
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• pp.76-83
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• 2001

The incompressible Reynolds-averaged Navier-Stokes equations are solved to predict the aerodynamic characteristics of an airship hull. The concept of pseudo-compressibility is employed to couple the pressure field with the velocity field. The upwind differencing method for spatial discretization and a line relaxation scheme for time integration are used. The flowfield around the low drag airship hull of fineness ratio 4 is solved for two Reynolds numbers with a wide range of angle of attack. The effect of Reynolds number and transition position is briefly examined together with the change in aerodynamic coefficients due to a gondola attached to the hull, and the results will be used as basic data for the design of a low drag airship hull.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제13권1호
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• pp.17-27
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• 2024

비디오 프레임 보간(Video Frame Interpolation)은 움직임의 연속성을 증가시켜 영상을 부드럽게 재생할 수 있어 영상, 미디어 분야에서 사용되는 중요한 기술이다. 딥러닝 기반 비디오 프레임 보간 연구에서 널리 사용되는 방법 중 하나인 커널 기반 방법(Kernel Based Method)의 경우, 지역적인 변화를 잘 포착하지만 전체적인 변화를 처리하는 데 한계가 있었다. 이에 본 논문에서는 주요 변화 포착에 집중하기 위한 특성맵 차분, Two Direction을 적용한 새로운 U-Net 구조를 통해 파라미터 수를 줄이면서 중간 프레임을 보다 정확하게 생성하고자 한다. 실험 결과 제안한 구조가 기존보다 Vimeo, Middle-burry 등의 일반적인 데이터셋과 새로운 YouTube 데이터셋에서 기존 모델보다 약 61% 더 적은 파라미터로 PSNR 수치가 최대 0.3 우수한 성능을 달성하였다. 본 논문에서 사용한 코드는 https://github.com/Go-MinSeong/SF-AdaCoF에서 확인 가능하다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1999년도 추계 학술대회논문집
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• pp.17-22
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• 1999

Convergence characteristics and efficiency of three implicit approximate factorization schemes(ADI, DDADI and MAF) are examined using 2-Dimensional compressible upwind Navier-Stokes code. Second-order CSCM(Conservative Supra Characteristic Method) upwind flux difference splitting method with Fromm scheme is used for the right-hand side residual evaluation, while generally first-order upwind differencing is used for the implicit operator on the left-hand side. Convergence studies are performed using an example of the flow past a NACA0012 airfoil at steady transonic flow condition, i. e. Mach number 0.8 at $1.25^{\circ}$ angle of attack. The results were compared with other computational results in order to validate the current numerical analysis. The results from the implicit AF algorithms were compared well in low surface with the other computational results; however, not well in upper surface. It might be due to lack of the grid around the shock position. Because the algorithm minimizes the errors of the approximate decomposition, the improved convergence rate with MAF were observed.

• 한국항해학회지
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• 제19권2호
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• pp.13-22
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• 1995

This paper presents the numerical analysis results of the viscous flow for a full ship model. The mass and momentum conservation equations are used for governing equations, and the flow field is discretized by the Finite-Volume Method for the numerical calculation. An algebraic grid and elliptic grid generation techniques are adopted for generation of the body-fitted coordinates system, which is suitable to ship's hull forms. Time-marching procedure is used to solve the three-dimensional unsteady problem, where the convection terms are approximated by the QUICK scheme and the 2nd-order central differencing scheme is used for other spatial derivatives. A Sub-Grid Scale turbulence model is used to approximate the turbulence, and the wall function is used at the body surface. Pressure and velocity fields are calculated by the simultaneous iteration method. Numerical calculations were accomplished for the Crude Oil Tanker(DWT 95,000tons, Cb=0.805) model. Calculation results are compared to the experimental results and show good agreements.

• 한국병원경영학회지
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• 제14권4호
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• pp.149-162
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• 2009

The purpose of this study is to design strategic hospital service based on each hospital's features. For this study, an assessment was conducted by 398 in-patents of one university hospital located in Seoul. The self-questionnaires, which were investigated from Oct. 15th to 29th in 2008, compared central reception desk with ward reception desk in satisfaction and re-use rate of patients. The major results of this study are as follow. First, according to each reception desk user, they have different satisfaction of it. As for the staff kindness, admission procedure, discharge procedure and manner of staff, those made patients be gratified as well. Second, when it comes to the intention of re-use, there were no significant features between them. Only convenience in admission and discharge procedure, however, was an attractive factor for the recommendation. Third, this study found out the reasons for higher re-use rate of central reception desk users. Regarding service, they were contented with the time for test and treatment. As for the hospital service, they would like to re-use this hospital because of convenient steps of paying interim fee and getting certificates. Forth, this study found out the reasons for higher re-use rate of ward reception desk users. As a point of hospital service view, they responded that respected privacy, hospital facility and general service were good for staying. As for the manner of staff, they mentioned nurses and staff in charge and whole staff members were kind. When it comes to the procedures of patient management, steps of discharge and paying interim fee were convenience. In conclusion, the results of this study suggest that providing a ward reception desk service can boost the satisfaction and re-use rate of in-patients. Furthermore, this strategic management method would be good for not only cutting the moving line but also efficient in-patient care system. These results can be used for the strategic hospital marketing field, as well. Even though this study has a limitation of the targeted populations which were only in a ward reception desk running hospital, it can say that having competitiveness in satisfaction of hospital service is good for promoting and differencing each hospital. Consequently, whole general management system would be adjusted first for differencing each hospital; however, this sort of additional factor should be concerned as well. I expect that this study would give meaningful data for designing strategic and differencing marketing method to lots of hospitals.

• 응용통계연구
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• 제32권5호
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• pp.721-740
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• 2019

영상처리 분야에서 중요한 분야인 잡음 제거는 통계적인 접근이 필요하지만 잡음에 대한 특정한 분포를 가정하기 어려우며 지역적 특징을 반영하는 공간 필터는 소표본에 해당하므로 모수적인 방법으로 접근할 수 없다. 1차 영상 미분과 2차 영상 미분은 영상에 포함된 잡음 수준에 따라 확연한 차이를 보이며 캐니 에지 검출기를 사용하면 보다 명확히 알 수 있다. 잡음 수준을 통계적으로 확인하고자 Fligner-Killeen 검정을 진행하고 붓스트랩 방법을 사용하였으며 추정된 잡음의 수준을 베타분포의 누적분포함수를 이용하여 0과 1사이의 값을 갖도록 하였다. 본 연구에서는 영상에 포함된 잡음 수준을 고려하는 잡음 제거 알고리즘을 제시하고자 한다.