• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.819-820
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• 2007

• 한국자동차공학회논문집
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• 제22권1호
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• pp.65-70
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• 2014

An Integrated Dynamics Control system with four wheel Steering (IDCS) is proposed and analysed in this study. It integrates and controls steer angle of front and rear wheel simultaneously to enhance lateral stability and steerability. An active front steer (AFS) system and an active rear steer (ARS) system are also developed to compare their performances. The systems are evaluated during brake maneuver and several road conditions are used to test the performances. The results showed that IDCS vehicle follows the reference yaw rate and reduces side slip angle very well. AFS and ARS vehicles track the reference yaw rate but they can not reduce side slip angle. On split-${\mu}$ road, IDCS controller forces the vehicle to go straight ahead but AFS and ARS vehicles show lateral deviation from centerline.

• 동력기계공학회지
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• 제12권4호
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• pp.18-25
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• 2008

This paper investigated the new calibration algorithm of a straight-type five-hole pressure probe necessary for calculating three-dimensional flow velocity components. The new data reduction method Includes a look-up, a geometry transformation such as the translation and reflection of nodes, and a binary search algorithm. This new calibration map was applied up to the application angle, ${\pm}55^{\circ}$ of a probe. As a result, this data reduction method showed a perfect performance without any kind of interpolation errors In calculating yaw and pitch angle from the calibration map.

• 한국자동차공학회논문집
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• 제20권2호
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• pp.15-20
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• 2012

This study is to propose and develop an integrated dynamics control system to improve and enhance the lateral stability and handling performance. To achieve this target, we integrate an AFS and a 4WS systems with a fuzzy logic controller. The IDCS determines active additional steering angle of front wheel and controls the steering angle of rear wheel. The results show that the IDCS improves the lateral stability and controllability on dry asphalt and snow paved road when double lane change and step steering inputs are applied. Yaw rate of the IDCS vehicle tracks reference yaw rate very well and body slip angle is reduced about by 50%. Response time of the IDCS vehicle is also decreased.

• 융합신호처리학회논문지
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• 제22권4호
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• pp.171-178
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• 2021

카라반은 외부의 물리적 요인에 쉽게 영향을 받아 탑승자에게 위험한 상황을 초래하는 경우가 많다. 따라서 탑승자의 안정성을 확보하기 위해 스웨이 현상을 사전에 예방할 수 있는 스웨이 저감 장치를 개발할 필요성이 있다. 본 논문에서는 견인차량과 카라반 사이의 Hitch angle을 최소화하는 것을 목표로 한다. 구체적으로는 견인차량과 카라반 각각에 장착된 IMU 센서를 통해 카라반의 초기 불안정성을 감지하고, PID 제어기를 이용하여 Hitch angle, Hitch yaw rate가 Desired hitch angle, Desired hitch yaw rate에 수렴할 수 있도록 제어 값을 산출한다. 산출된 제어 값에 따라 카라반 좌우 브레이크에 다른 제동토크를 생성하여 분배하고 제어한다. 주행 실험을 통해 스웨이 저감 장치의 성능을 검증한 결과, 제어하지 않은 경우보다 Hitch angle이 감소한 것을 확인할 수 있었고, 횡 방향 안정성 향상률은 제어 전에 비해 78.9% 향상된 것을 확인하였다.

• 대한환경공학회지
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• 제31권4호
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• pp.272-277
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• 2009

국내 석탄화력발전소의 대용량 보일러를 대상으로 연소용 이차공기의 수평분사각을 변경한 경우에 대하여 화로에서의 연소특성과 NOx 발생특성을 전산유체역학적으로 해석하였다. 열유동해석 결과를 실제 운전데이터와 비교하여 해석의 신뢰성을 확인하할 수 있었다. 분사각을 $20^{\circ}$까지 증가시킬 경우 노즐 근처에서의 재순환유동 감소, 화로출구 NOx 감소와 미연분 증가를 가져왔으며 화구의 형태가 많이 변화되는 것을 관찰하였다. 본 연구결과는 A화력발전소의 연소방식을 변경하는 경우 기본적인 설계 및 운전 데이터로 활용하고자 한다.

• Wind and Structures
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• 제17권3호
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• pp.317-343
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• 2013

When evaluating flutter instability, it is often assumed that incident wind is normal to the longitudinal axis of a bridge and the flutter critical wind speed estimated from this direction is most unfavorable. However, the results obtained in this study via oblique sectional model tests of four typical types of bridge decks show that the lowest flutter critical wind speeds often occur in the yaw wind cases. The four types of bridge decks tested include a flat single-box deck, a flat ${\Pi}$-shaped thin-wall deck, a flat twin side-girder deck, and a truss-stiffened deck with and without a narrow central gap. The yaw wind effect could reduce the critical wind speed by about 6%, 2%, 8%, 7%, respectively, for the above four types of decks within a wind inclination angle range between $-3^{\circ}$ and $3^{\circ}$, and the yaw wind angles corresponding to the minimal critical wind speeds are between $4^{\circ}$ and $15^{\circ}$. It was also found that the flutter critical wind speed varies in an undulate manner with the increase of yaw angle, and the variation pattern is largely dependent on both deck shape and wind inclination angle. Therefore, the cosine rule based on the mean wind decomposition is generally inapplicable to the estimation of flutter critical wind speed of long-span bridges under skew winds. The unfavorable effect of yaw wind on the flutter instability of long-span bridges should be taken into consideration seriously in the future practice, especially for supper-long span bridges in strong wind regions.

• 풍력에너지저널
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• 제9권4호
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• pp.9-15
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• 2018

In a previous study, a technique for measuring wind speed and direction by using a roll-rotating three-axis ultrasonic anemometer was proposed and verified by wind tunnel tests. In the tests, instead of a roll sensor, roll angle was trimmed to make no up flow in the transformed wind speeds. Verification was done in point of the residual error of the rotation effect treatment. In this study, roll angle was measured from the roll motor encoder and the transformed wind speed and direction on the test section axis were compared with the ones provided to the test section. As a result, up to yaw $20^{\circ}$ at a wind speed of 12 m/sec or over, the RMS error of wind speed was within the double of the ultrasonic anemometer error. But at yaw $30^{\circ}$, it was over the double of the ultrasonic anemometer error. Regardless of wind speed, at yaw $20^{\circ}$ and $30^{\circ}$, the direction error was within the double of the ultrasonic anemometer error. But at yaw $10^{\circ}$ or less, it was within the error of the ultrasonic anemometer itself. This is a very favorable characteristic to be used for wind turbine yaw control.

• 대한기계학회논문집A
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• 제23권6호
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• pp.931-942
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• 1999

This paper develops a 3 DOF vehicle model which includes lateral, roll and yaw motion to study a 4WS vehicle. The model is used for the simulation of a 4WS vehicle behavior, and to derive a control algorithm for rear wheel steering. This paper uses a feedforward plus feedback control scheme to compute a rear wheel steering angle. The feedforward control scheme for computing the first rear wheel steering angle uses a gain which is acquired by multiplying a proper value on a gain to maintain a zero sideslip angle. The feedback control scheme for computing the second rear wheel steering angle uses fuzzy logic and model following control scheme. A linear 2 DOF model is used as a reference model for model following control, and is derived from the developed 3 DOF model by neglecting sprung mass roll motion. A reference state variable is yaw rate, and is computed using the linear 2 DOF model. J-turn and lane change maneuver simulation are performed to show the effectiveness of the developed control scheme. The simulation results show that the 4WS vehicle with the developed control scheme has much better performance in yaw rate, lateral acceleration, roll angle, and sideslip angle than the 2WS vehicle. Also, the results show that the performance of the developed control is close to the one of an optimal control which assumes all states are perfect.

• 한국군사과학기술학회지
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• 제9권1호
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• pp.127-134
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• 2006

The protection capability against an enhanced long rod(L/D=30) with yaw is investigated numerically and compared with that of shorter one(L/D=15). In addition details of interactions between yawed long rods and oblique plate velocity are examined. Through the simulation results, we find that dual flying plates system is more effective with longer rod due to the elongated disturbance. The protection performance is more effective for the penetrator with $+6^{\circ}$ of yaw angle than that with a yaw angle of $-6^{\circ}$.