• 드라이브 ㆍ 컨트롤
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• 제21권1호
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• pp.16-21
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• 2024

The yaw gearbox is a key device in a wind power generator that improves power generation efficiency by rotating hundreds of tons (400 to 600 tons) of nacelle so that the blade reaches 90 degrees in the wind direction. Recently, installation sites have been advancing from land to sea as they have become super-large at (8-12) MW to increase the economic feasibility of wind power generators and utilize excellent wind resources, and the target life of large wind power generators is 25 to 30 years. The yaw gearbox of 6 to 12 sets is installed in a very complex place inside the nacelle on the tower with parallels, and it is important to secure the reliability of the yaw gearbox because if a failure occurs after installation, it costs tens to hundreds of times the price of a new product to restore. In this study, equivalent loads were calculated by analyzing failure mode and field data, accelerated life test conditions were established, and a test device was constructed to perform the accelerated life tests and performance tests to ensure the reliability of the gearbox.

• 한국항공우주학회지
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• 제37권7호
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• pp.669-677
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• 2009

일반적으로 롤/요 평면상의 nutation 운동이 있는 피치 모멘텀 바이어스 시스템을 정지궤도 위성인 통신위성에서 주로 사용되어 왔으나 본 논문에서는 저궤도 위성의 경우에 대해 최소 휠 개수인 2개 반작용휠로 구성된 피치 모멘텀 바이어스 시스템을 휠 모멘텀 제어방식으로 피치축과 롤축 자세제어를 수행하는 방안을 살펴보았다. PI-제어기를 사용한 휠 모멘텀 제어 방식의 경우 휠 베어링 마찰 등 반작용휠에 가해지는 외란에 대한 강건성 보장을 해석적으로 분석하였으며, 롤축 자세에러 측정치와 요축 모멘텀 선형 제어기 설계를 위한 전달함수를 제시하였고, 시스템에 대한 이해도를 높이고, 외란 영향 및 모멘텀 바이어스 크기 등 필요한 설계 인자 선정을 위해 시스템에 대한 분석을 수행하였다.아울러 요축 모멘텀 PID-제어기를 사용한 모멘텀 바이어스 시스템의 롤/요축 자세제어 설계결과 및 시뮬코타키나발루레이션 결과를 제시하였다.

• 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.

• 한국소음진동공학회논문집
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• 제18권10호
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• pp.997-1005
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• 2008

Linear motor stage is a useful device in precision engineering field because of its simple power transmission mechanism and accurate positioning. Even though linear motor stage shows fine positioning accuracy along travel axis, geometric dependent errors which relay on machining and assembling accuracy should be addressed to increase total positioning performances. In this paper, we suggests a cost effective yaw error compensation servo-system which is mounted on platform of the stage and nullify travel position dependent yaw error. This paper also provides a method of designing a sliding mode control which is robust to existing friction disturbance and model uncertainties. The reachability condition of slinding mode control for the yaw error compensating servo-system has been established. From some experimental results by using an experimental set-up, the sliding mode control showed its effective in disturbance rejection and its performance was superior to conventional linear controls.

• International Journal of Control, Automation, and Systems
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• 제4권2호
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• pp.255-270
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• 2006

In this paper, a design method of nonlinear autopilot for ship-to-ship missiles is proposed. Ship-to-ship missiles have strongly coupled dynamics through roll, yaw, and pitch channel in comparison with general STT type missiles. Thus it becomes difficult to employ previous control design method directly since we should find three different solutions for each control fin deflection and should verify the stability for more complicated dynamics. In this study, we first propose a control loop structure for roll, yaw, and pitch autopilot which can determine the required angles of all three control fins. For yaw and pitch autopilot design, missile model is reduced to a minimum phase model by applying a singular perturbation like technique to the yaw and pitch dynamics. Based on this model, a multi-input multi-output (MIMO) nonlinear autopilot is designed. And the stability is analyzed considering roll influences on dynamic couplings of yaw and pitch channel as well as the aerodynamic couplings. Some additional issues on the autopilot implementation for these coupled missile dynamics are discussed. Lastly, 6-DOF (degree of freedom) numerical simulation results are presented to verify the proposed method.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제38권
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• pp.4.1-4.6
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• 2016

Background: Most cases of facial asymmetry involve yaw deformity, and determination of the yaw correction level is very difficult. Methods: We use three-dimensional soft tissue simulation to determine the yaw correction level. This three-dimensional simulation is based on the addition of cephalometric prediction to gradual yaw correction. Optimal yaw correction is determined visually, and an intermediate splint is fabricated with computer-aided design and computer-aided manufacturing. Application of positioning devices and the performance of horseshoe osteotomy are advisable. Results: With this procedure, accurate repositioning of jaws was confirmed and patients obtained fairly good facial contour. Conclusions: This procedure is a promising method for a widespread, predictable treatment of facial asymmetry.

• 한국자동차공학회논문집
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• 제19권4호
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• pp.38-46
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• 2011

This paper presents roll angle estimator which used Kalman filter. Recently, the uses of the ELSD (Electronic Limited Slip Differential) and TVD(Torque Vectoring Differential) for vehicle yaw control are studied in many researches. However the roll angle can be negative effect of ELSD and TVD control. Therefore the information of roll angle can be used for vehicle yaw control. Moreover it can be used for rollover prevent control. Recently, most of the vehicles use lateral acceleration and yaw rate sensor. In this paper, design of Kalman filter which used lateral acceleration and yaw rate information is developed. In this paper, in order to verify the estimator ability, the CarSim and Matlab/Simulink are used.

• 제어로봇시스템학회논문지
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• 제15권11호
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• pp.1130-1136
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• 2009

A new control algorithm for the yaw motion control of a unicycle robot has been proposed in this paper. With the increase of life quality, there are various transportation systems such as segway and unicycle robot which provide not only transportation but also amusement. In most of the unicycle robots share the same technology in that the directions of roll and pitch are controlled by the balance controllers, allowing the robots to maintain balance for a long period by continuously moving forward and backward. However, one disadvantage of this technology is that it cannot provide the capability to the robots to avoid obstacles in their path way. This research focuses to provide the yawing function to the unicycle robot and to control the yaw motion to avoid the obstacles as desired. For the control of yawing motion, the yaw angle is adjusted to the inertia generated by the velocity and torque of a yawing motor which is installed in the center axes of the unicycle robot to keep the lateral control simple. Through the real experiments, the effective and robustness of the yawing control algorithm has been demonstrated.

• 한국항공운항학회지
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• 제25권3호
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• pp.74-80
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• 2017

As for A rotary wing aircraft, the configuration change about split yaw swaged rod was executed to improve hit treat capability for dealing with a long rod. The purpose of this study was to analyze if or not the quality of the split yaw swaged rod was obtained, and so the flight safety was ensured or not. Buckling analysis, Coupling Thread Strength Analysis, Thermal Stress analysis and Rod Natural Frequency Analysis were executed for structural analysis. The results of the analysis were presented that the split rod had the sufficient margin of safety and so there were no anomalies in the limit load and no failures in the ultimate load. And there were no resonances in result of natural frequency analysis. In conclusion, this study showed that the split yaw swaged rod had structural safety, so flight safety of rotary wing aircraft was secured and there was no problem in aircraft operation. It is certain that the technology of splitting the yaw swage rod will contribute to the operational Safety of the rotary wing aircraft in the future.

• 한국항공우주학회지
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• 제32권4호
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• pp.34-42
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• 2004

본 논문에서 위성의 롤/요 자세제어를 위해 더블 김벌을 이용하며 2 종류의 피드백 제어기를 설계하였다. 하나는 롤과 요 제어압력에 위상 차이가 없는 PD 제어기이고 다른 하나는 요 제어입력에 위상지연이 있는 PD 제어기이다. 위상지연 보상기는 요각 제어를 위한 1차 시스템으로 설계하였다. 일정한 외란과 초기 뉴테이션 오차가 있는 경우에 대해 시뮬레이션하여 요각의 정상상태 오차와 rising time 의 결과로부터 위상지연 보상기가 효과적임을 검증하였다. 본 시뮬레이션에 사용된 변수 값은 무궁화위성 1호를 대상으로 하였다.