• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2004년도 춘계 학술대회논문집
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• pp.23-26
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• 2004

Drag prediction is sought for the aifoil having laminar and turbulent flow characteristics with CFD code being unable to predict transition to turbulent flow. Laminar flow simulation presents some insight to the transition position. Separate simulations with laminar and turbulent flow and their combination estimate the drag of the airfoil containing laminar and turbulent flow characteristics.

• 한국지능시스템학회논문지
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• 제21권2호
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• pp.178-185
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• 2011

본 논문은 상태변수 평준화 및 되먹임구조를 이용하여 무인잠수정의 위치추정을 개선하기 위한 다중센서 융합 기반의 위치추정 알고리즘을 제안한다. 이를 위해 먼저 상대적으로 오차가 큰 주 센서인 INS와 오차가 작은 보조센서인 DVL에서 측정되는 상태변수를 예측단계 이전에 융합하여 상태변수 평준화 과정을 수행한다. 그 다음, 평준화된 상태변수를 각 필터에 입력하여 예측 및 수정단계의 칼만 필터링 과정을 통해 최종 수정된 상태변수를 융합시키며, 마지막으로 이를 다시 주센서에 되먹임함으로서 무인잠수정의 위치추정을 개선한다. 평가를 위해 무인잠수정의 기동모델에 대한 시뮬레이션을 실시하여 기동경로를 생성하고 제안 알고리즘을 적용하여 위치추정 성능을 확인한다. 평가 결과, 제안 알고리즘이 다중센서 융합 알고리즘 중 가장 우수한 위치추정 성능을 보였으며, 또한 기동침로가 변경되는 구간에서도 강인한 위치추정이 가능하다는 것이 증명되었다.

• 한국산업융합학회 논문집
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• 제22권4호
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• pp.435-445
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• 2019

Ball screw drives are widely used in industry, and many studies have been devoted on precise, fast and robust control of ball screw drives. In this study, a novel position control algorithm for ball screw drives is proposed, which consist of a PD controller, a friction feedforward and a disturbance observer. The dynamics and the position error of such controller are analyzed to establish an error model, which can be used to predict the resulting position error of the given desired trajectory. Using the proposed error model, the desired trajectory can be modified so that the predicted position error can be compensated in a feedforward manner. The proposed algorithm does not require the model of the system for the error prediction, and thus can be easily applied to conventional control systems. The performance of the system is verified through simulations and experiments.

• Design & Manufacturing
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• 제14권4호
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• pp.40-45
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• 2020

In a vehicle-to-vehicle accident, the impact posture, braking status, final stopping position, collision point and collision speed are important factors for accident reconstruction. In particular, the speed of collision is the most important issue. In this study, the collision speed and the final stopping position in the tunnel were estimated using PC-CRASH, a vehicle crash analysis program used for traffic accident analysis, and the final stopping position of the simulation and the final stopping position of the traffic accident report were compared. When the Pride speed was 0km/h or 30km/h and the Sorento speed was 100m/h, the simulation results and reports matched the final stopping positions and posture of the two vehicles. As a result of the simulation, it can be estimated that Pride was collided in an almost stationary state.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 춘계학술대회 논문집
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• pp.77-80
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• 2001

IC lead frame needs the precision shape for good efficiency. In the blanking process, there are many parameter effected the dimensional accuracy : lead width, blanking order, striper force, tool clearance etc. In this research, the4 undesirable defects appeared in the final blanking process. so we measured the deflection of lead according to the stripper force using $PAM-STAMP_{TM}$. In the result, the deflection was decreased by increasing the stripper force properly. and we changed the blanking order on the test model. In the blanking order, deflection is good from the outer line position blanking to center line position. so we can design the precision die without tryout by the prediction of the lead deflection.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2017년도 추계학술대회
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• pp.145-147
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• 2017

Tracking filter plays a key role in accurate estimation and prediction of maneuvering vessel's dynamics. The third-order ${\alpha}-{\beta}-{\gamma}$ filter is one of the special cases of the general solution provided by the Kalman filter. Fading memory algorithm performs a better performance in numerous of ${\alpha}-{\beta}-{\gamma}$ filter algorithms. This study aims to optimize the fourth-order fading memory algorithm ${\alpha}-{\beta}-{\gamma}-{\eta}$ filter, which is extended form ${\alpha}-{\beta}-{\gamma}$ filter, to get much more accurate position of high dynamic target on the condition that the own ship is also high dynamic.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.125-129
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• 1996

In this study, a method is proposed for the cutting force prediction of Ball-end milling process using Z-map is proposed. Any types of cutting area generated from previous cutting process can be expressed in z-map data. Cutting edge of a ball-end mill is divided into a set of finite cutting edges and the position of this edge is projected to the cross-section plane normal to the Z-axis. Comparing this projected position with Z-map data of cutting area and determining whether it is in the cutting region, total cutting force can be calculated by means of numerical integration. A series of experiments such as side cutting and upward/downard cutting was performet to verify the simulated cutting force.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.768-783
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• 2020

Typically, a Dynamic Positioning System (DPS) uses a PID feed-back system, and it often adopts a wind feed-forward system because of its easier implementation than a feed-forward system based on current or wave. But, because a ship's drifting motion is caused by wind, current, and wave drift loads, all three environmental loads should be considered. In this study, a motion predictive control for the PID feedback system of the DPS is proposed, which considers the three environmental loads by utilizing predicted drifted ship positions in the future since it contains information about the three environmental loads from the moment to the future. The prediction accuracy for the future drifted ship position is ensured by adopting deep learning algorithms and a replay buffer. Finally, it is shown that the proposed motion predictive system results in better station-keeping performance than the wind feed-forward system.

• 대한전자공학회논문지SP
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• 제40권3호
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• pp.185-193
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• 2003

MPEG-4 삼차원 메쉬 모델 압축(3DMC) 표준에서 사용되는 평행사변형예측 방법은 예측하고자 하는 꼭지점이 인접한 꼭지점들과 같은 평면상에 있다고 가정하여 하나의 삼각형 내에 있는 인접한 세 개의 꼭지점 좌표 값만을 이용하므로 예측 효율이 좋지 않다. 본 논문에서는 삼각형 주변의 꼭지점 좌표값과 인접하는 삼각형 사이의 사잇각을 고려한 통합예측을 이용하여 삼차원 메쉬 모델의 기하정보를 부호화하는 방법을 제안한다. 우선 제안한 꼭지점 계층탐색 방법으로 위상학적으로 거리가 가까운 점들을 탐색하여 정렬된 값들의 기하학적 상관도를 높이고, 정렬된 삼차원 메쉬의 꼭지점 순서에 따라 주변의 꼭지점 값들을 이용하여 현재 꼭지점 값을 예측한다. 본 논문에서 제안한 통합예측 방법은 다양한 VRML 포맷의 테스트 모델에 대해서 기존의 MPEG-4 3DMC의 평행사변형예측 방법보다 우수한 성능을 보인다.

• Journal of Electrical Engineering and Technology
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• 제7권5호
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• pp.797-806
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• 2012

Fault detection and isolation (FDI) algorithms provide fault monitoring methods in GPS measurement to isolate abnormal signals from the GPS satellites or the acquired signal in receiver. In order to monitor the occurred faults, FDI generates test statistics and decides the case that is beyond a designed threshold as a fault. For such problem of fault detection and isolation, this paper presents and evaluates position domain integrity monitoring methods by formulating various pseudorange prediction methods and investigating the resulting test statistics. In particular, precise measurements like carrier phase and Doppler rate are employed under the assumption of fault free carrier signal. The presented position domain algorithm contains the following process; first a common pseudorange prediction formula is defined with the proposed variations in pseudorange differential update. Next, a threshold computation is proposed with the test statistics distribution considering the elevation angle. Then, by examining the test statistics, fault detection and isolation is done for each satellite channel. To verify the performance, simulations using the presented fault detection methods are done for an ideal and real fault case, respectively.