• EDISON SW 활용 경진대회 논문집
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• 제6회(2016년)
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• pp.90-95
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• 2016

본 연구에서는 교육 및 연구를 위한 CFD 해석 프로그램인 EDISON_CFD 프로그램을 이용하여 화물 트럭의 후면부 형상변화에 따른 공력특성을 분석해보았다. 먼저 추가적인 부착물을 장착하지 않은 기본적인 형상의 화물트럭의 공력특성을 확인 후, 후면부에 여러 형상의 Boat tail(보트 테일)과 전면부에 Cap-roof fairing(캡루프 페어링)이 부착된 형상을 해석하여 트럭이 받는 항력 감소를 통해 최적형상을 찾아가는 연구를 수행하였다. Cap-roof fairing이 부착된 형상에서 $15^{\circ}$의 특성길이가 0.3인 Boat tail에서 가장 좋은 항력 감소 효과를 얻을 수 있었다. Cap-roof fairing의 경우 6%의 항력 계수 감소를 보였고, Boat tail에서 20%의 항력 계수 감소효과를 관찰할 수 있었다. Boat tail의 각도와 길이를 변수로 하여 여러 해석을 진행한 결과 최적화된 형상을 선정할 수 있었다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2004년도 추계 학술대회논문집
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• pp.43-46
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• 2004

Numerical analysis for pressure drag on boattail afterbodies have been studied by Mach number, boattail angle and length ratio of body diameter and base diameter using CFD-FASTRAN that the commercial external flow CFD code. The numerical results have been compared with the experimental data that have been shown pressure drag reduction and supersonic turbulent flow characteristics for boattail afterbodies. And the prediction equation tot boattail base drag has been made by the numerical results about Mach number and boattail configuration parameters.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2868-2872
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• 2007

In this study, a passive control using a boat-tail device is conducted for a three-dimensional car model in ground proximity. We consider various boat-tails and investigate the mechanism of drag reduction by them. By varying the length and slant angle of boat-tail, we obtain drag reductions up to 40%. From the oil-surface flow visualization and hot-wire measurement, the drag reduction by the boat-tail is characterized by the shear-layer instability and reattachment on the boat-tail, forming a small separation bubble at the upstream part of boat-tail surface, resulting in the delay of main separation and drag reduction. At high slant angles, the flow fully separates and drag is nearly same as that of no control.

• 대한전자공학회논문지
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• 제24권5호
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• pp.753-761
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• 1987

Approximation of a Cartesian straight line motion with linear interpolation in the joint space has many desirable advantages and applications. But inappropriate determination of the corresponding subtravelling and transition times makes such joint-trajectories violate the input torque/force constraints. An approach that can overcome this difficult and yield the joint trajectories utilizing the allowable maximum input torque/force is established in this paper. The effectiveness of these results is demonstrated by using a three-joint revolute manipulator.

• 한국가시화정보학회지
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• 제13권1호
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• pp.9-14
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• 2015

There have been many attempts to reduce the cost of transportation. Especially, drag reduction of heavy vehicles has enormous influence on energy saving by reducing the driving power of the vehicles. In this study, the effects of drag-reducing additive devices such as side skirt, boat tail and cab-roof fairing on the drag reduction of a 5 ton truck model were experimentally investigated. The aerodynamic performance of these flow-control devices attached to heavy vehicle was evaluated through wind tunnel test. In addition, flow patterns around the truck model were visualized by using smoke tube method. The drag coefficient is reduced by up to 5.7%, 7.16% and 22.2% by the side skirt, boat tail and cab-roof fairing, respectively. The interactive effect of the side skirt and boat tail was also investigated.

• 대한전자공학회논문지
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• 제25권2호
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• pp.144-151
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• 1988

Between any two points in the Cartesian space, the straight motion has many distinct advantages in path/trajectory plannings, specially in a crowded workspace. But to achieve this motion is a nontrivial task. One standard way to approximate this motion is to plae enough intermediate points along the desired path and linearly interpolate two adjacent intermediate points in the joint space. In this approach, however, the determination of the minimum number of intermediate points is very important from several aspects. A scheme that can effectively accomplish this purpose is established in this paper. This scheme is based on several search methods. The results are demonstrated using the PUMA 560 series manipulator.

• 한국해양공학회지
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• 제24권4호
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• pp.23-31
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• 2010

The flow around a remotely-operated vehicle (ROV) has been investigated numerically to improve the resistant performance by modifying the hull form of the ROV. In the case of the base hull form considered in this study, form drag rather than friction drag was the dominant component of total drag. Subsequently, the surfaces that were most susceptible to local pressure effects were modified to give them a more streamlined shape. Eleven different hull forms were chosen to undergo surface modification for drag reduction. In addition, four different boat-tail appendages with different slant angles were installed at the stern to reduce the wake vortices that are induced by the local regions of very low pressure. Consequently, a total of 11 different hull forms for drag reduction were considered. The final hull form, which combined the hull for which surface modification resulted in the lowest drag with a boat-tail appendage with a 15-degree slant angle, resulted in a drag reduction of 20%.

• 한국항공우주학회지
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• 제49권1호
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• pp.41-52
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• 2021

발사체가 대기 중에서 상승 비행 시 공기역학적 현상에 기인한 음향하중을 받는데 천음속 영역에서 그 영향이 커진다. 본 연구에서는 천음속 조건에서 해머헤드 발사체 외부에 작용하는 음향하중을 ��-ω SST 난류모델 기반 IDDES 법으로 해석하여 시간 평균 압력계수, 표면 압력섭동, 압력섭동 파워 스펙트럼을 분석하고 가용한 풍동실험 데이터와 비교하였다. IDDES 결과의 격자 의존성을 검토하였으며, 난류 스케일 분해가 가능한 적절한 계산격자를 사용한 경우 천음속 헤머헤드 발사체의 특징적인 유동 현상인 페어링 어깨에서의 유동 박리와 박리 유동의 후방 동체 재 부착, 보트 테일 후방에서의 높은 압력섭동을 공학적으로 유의미한 정확도로 예측 가능함을 확인하였다.

• 한국기후변화학회지
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• 제7권2호
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• pp.177-184
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• 2016

Recently, the need for technology development of commercial vehicle fuel consumption has emerged. Fuel economy improvement of transport equipment and transportation efficiency, and increasing attention to the logistics cost reduction measures. Increasing attention to the logistics cost reduction measures by fuel economy improvement of transport equipment and transportation efficiency. In this study, we have installed aerodynamic reduction device (side skirt, boat tail) to 14.5 ton cargo trucks and 45 ft tractor-trailers. And the fuel consumption was compared installed before and after. Fuel economy assessment for the aerodynamic reduction value device was tested by modifying the SAE J1321 Joint TMC/SAE Fuel Consumption Test Procedure - Type II test in according domestic situation. Greenhouse gas reductions were calculated in accordance with the scenario, including fuel consumption test results. When the 14.5 ton cargo trucks has been equipped with side skirts and boat tail, it confirmed the improvement in fuel efficiency of 4.72%. One Heavy-duty truck's the annual greenhouse gas reductions value are $6.86ton\;CO_2\;eq$. And if applying the technology to more than 50% of registered 15 ton trucks, greenhouse gas reductions are calculated as $686,826ton\;CO_2\;eq./yr$.