• 대한기계학회논문집A
• /
• 제22권2호
• /
• pp.380-390
• /
• 1998

In the present work a finite element formulation using dynamic explicit time integration scheme is used for numerical analysis of auto-body panel stamping processes. The lumping scheme is employed for the diagonal mass matrix and linearizing dynamic formulation. A contact scheme is developed by combining the skew boundary condition and direct trial-and-error method. In this work, for economic analysis the faster punch velocity and the mass scaling method are introduced. To investigate the effects of punch velocity and mass scaling, the various values of punch velocity and the various mass scalings are used for numerical analysis. Computations are carried out for analysis of complicated auto-body panel stamping processes such as forming of an oil pan and a fuel tank.

• 한국정밀공학회지
• /
• 제21권10호
• /
• pp.115-126
• /
• 2004

In the present work a finite element formulation using dynamic-explicit time integration scheme is used for numerical analysis of auto-body panel stamping processes. The lumping scheme is employed for the diagonal mass matrix and dynamic explicit formulation. Analyzed auto-body panel stomping process correction of forming using software called Dynaform using dynamic extensive method. Further, the simulated results for the auto-body panel stamping processes are shown and discussed. Its application is being increased especially in the automotive industrial area for the cost reduction, weight saving, and improvement of strength.

• 한국기계가공학회지
• /
• 제3권4호
• /
• pp.63-72
• /
• 2004

In this paper, a finite element formulation using dynamic-explicit time integration scheme is used for numerical analysis of auto-body panel stamping processes. The lumping scheme is employed for the diagonal mass matrix and dynamic explicit formulation. Auto-body panel forming is analyzed by using dynamic-explicit finite element method. Further, the simulated results of the auto-body panel stamping processes are shown and discussed. Its application is being increased especially in the stamping industrial area for the cost reduction, weight saving, and improvement of strength.

• 대한기계학회논문집B
• /
• 제20권11호
• /
• pp.3589-3597
• /
• 1996

The Reynolds-averaged Navier-Stokes equations with the equations of the k-.epsilon. turbulence model are solved numerically in a general curvilinear system for a three-dimensional turbulent flow around an Ahmed body. The simulation is especially aimed at the evaluation of three finite differencing schemes for the convection term, which include the upwind differencing scheme(UDS), the second order upwind differencing scheme(SOU scheme) and the QUICK scheme. The drag coefficient, the velocity and pressure fields are found to be changed considerably with the adopted finite differencing schemes. It is clearly demonstrated that the large difference between computation and experiment in the drag coefficient is due to relatively high predicted values of pressure drag from both front part and vertical rear end base. The results also show that the simulation with the QUICK or SOU scheme predicts fairly well the flow field and gives more accurate drag coefficient than other finite differencing scheme.

• 한국통신학회논문지
• /
• 제36권10C호
• /
• pp.597-604
• /
• 2011

본 논문에서는 의료용 in-body WBAN (Wireless Body Area Network) 시스템을 위한 GM (Group Manchester code) 변조 방식을 제안한다. 현재 IEEE에서는 WBAN 시스템을 802.15. TG (Task Group) 6로 지정하고 이에 관한 표준화를 진행하고 있다. 높은 전력 효율이 요구되는 WBAN 시스템을 위해 최근 표준화 그룹에서는 PPM(Pulse Position Modulation) 신호 간의 grouping을 통하여 전송률 이득을 얻을 수 있는 GPPM (Group Pulse Position Modulation) 변조 방식이 제안된 바 있으나, 기존 GPPM 방식은 복조 과정의 SNR 손실 및 gray coding의 부재로 인한 BER 성능 열화가 나타나는 단점이 존재한다. 따라서 본 논문에서는 PPM 보다 잡음 성능이 우수한 Manchester code를 기반으로, GM 방식의 BER 성능 최대화를 위한 복조 방식 및 turbo coded GM을 위한 LLR (Log Likelihood Ratio) 판정 방식을 제안하였으며, 다양한 성능 2 분석을 통해 제안된 방식의 우수성을 입증하였다.

• 한국전산유체공학회지
• /
• 제2권1호
• /
• pp.46-53
• /
• 1997

The flow field around a three dimensional minivan-like body has been simulated. This study solves 3-D unsteady incompressible Navier-Stokes equations on a non-orthogonal curvilinear coordinate system using second-order accurate schemes for the time derivatives, and third/second-order scheme for the spatial derivatives. The Marker-and-Cell concept is applied to efficiently solve continuity equation. A H-H type of multi-block grid system is generated around a three dimensional minivan-like body. Turbulent flows have been modeled by the Baldwin-Lomax turbulent model. To validate present procedure, the flows around the Ahmed body with 12.5° of slant angle are simulated. A good agreement with other numerical results is achived. After code validation, the flows around a mimivan-like body are simulated. The simulation shows three dimensional vortex-pair just behind body. The flow separation is also observed on the rear of the body. It has concluded that the results of present study properly agreed with physical flow phenomena.

• 한국기계가공학회지
• /
• 제17권5호
• /
• pp.161-172
• /
• 2018

This paper proposed the robot vision control method to track a moving rigid body target using the vision system model that can actively control camera parameters even if the relative position between the camera and the robot and the focal length and posture of the camera change. The proposed robotic vision control scheme uses a batch method that uses all the vision data acquired from each moving point of the robot. To process all acquired data, this robot vision control scheme is divided into two cases. One is to give an equal weight for all acquired data, the other is to give weighting for the recent data acquired near the target. Finally, using the two proposed robot vision control schemes, experiments were performed to estimate the positions of a moving rigid body target whose spatial positions are unknown but only the vision data values are known. The efficiency of each control scheme is evaluated by comparing the accuracy through the experimental results of each control scheme.

• 대한감각통합치료학회지
• /
• 제7권1호
• /
• pp.47-57
• /
• 2009

목적: 본 논문에서는 감각통합치료프로그램이 발달장애아동의 신체도식과 실행능력에 어떠한 영향을 미치는가에 대하여 알아보았다. 연구방법: 30명의 발달장애아를 대상으로 6주 동안 Ayres의 감각통합이론을 근거로 변형된 발달장애아 감각통합 치료프로그램을 적용하여 실시하였다. 연구 대상자의 실행능력의 평가는 신체도식 검사(한점 모방 검사, 신체 6퍼즐 맞추기 검사), 실행검사(언어지시실행, 구강실행, 순서실행) 및 감각통합실행검사(SIPT)를 통하여 데이터를 수집하였으며 치료 전과 치료 후의 변화를 알아보기 위하여 대응표본 t-검정으로 통계처리 하였다. 결과: 1. 감각통합치료프로그램이 발달장애아의 신체도식능력, 즉 한 점 모방과 신체 6 퍼즐 맞추기 능력에서 치료 전 후에서 유의한 차이를 나타내었다(p<0.01). 2. 감각통합치료프로그램이 발달장애아의 실행능력, 즉 언어지시실행, 구강실행 과 순서실행 모두에서 치료 전 후에서 유의한 차이를 나타내었다(p<0.01). 3. 감각통합치료프로그램이 발달장애아의 감각통합실행능력(SIPT)에서 유의한 치료 효과를 나타내었다(p<0.01).

• 한국해양공학회지
• /
• 제31권1호
• /
• pp.1-7
• /
• 2017

There are two wave modes induced by an oscillating body on the free surface of a two-layer fluid: the barotropic and baroclinic modes. To investigate the generated waves composed of two modes, a radiation problem involving a heaving rectangular body was solved in a numerical wave tank. A new artificial damping zone scheme was developed and applied in the frequency-domain analysis. The performance of this damping scheme was compared with given radiation boundary conditions for various conditions. The added mass and radiation damping coefficients for the heaving rectangular body were also calculated for various fluid-density ratios.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2022년도 추계학술대회
• /
• pp.400-403
• /
• 2022

본 논문은 가시화 기반 LBVH(Linear Bounding Volume Hierarchy))을 이용한 빠른 GPU기반 N-body 충돌 체크 알고리즘을 제안한다. 본 알고리즘은 움직이는 n-body 개체에 대한 수정된 모튼코드(Morton code)를 이용하며, 이 모튼코드는, 일반적으로 사용되는 개체의 위치 정보뿐 아니라 이 개체가 스크린상에 차지하는 가시화 영역 정보를 이용하기 때문에, 카메라의 위치 및 방향에 따라 화면상에 차지하는 영역이 작은 개체에 대한 빠른 GPU기반 정렬(sorting)이 가능하게 된다. 실험을 통해, 본 논문에서 제안하는 방법이 기존 방법보다 15%이상 성능 향상이 있음을 알게 되었다