• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2009년도 한국우주과학회보 제18권2호
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• pp.29.1-29.1
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• 2009

이 연구는 별 관측을 통해 점 퍼짐 함수(PSF)를 측정하고 나이퀴스트 주파수에서 변조 전달 함수(MTF)을 계산하여 주파수 영역에서 저궤도 광학 위성의 영상품질 평가방법을 도출하였다. 가상 별 영상을 생성하고 IRAF로 2차원의 점 퍼짐 함수를 얻었고 MATLAB으로 점 퍼짐 함수를 2차원 푸리에 변환하여 변조 전달함수를 계산하였다. 공간 영역에서는 점 퍼짐 함수의 모양을 통해서도 영상품질을 검증할 수 있다. Along/Across-Track의 모양이 일치하고 중심에서 좌우대칭이며 델타함수에 가까울수록 좋은 품질의 영상을 의미한다. Along/Across-Track의 점 퍼짐 함수 모양차이는 Line Rate나 Time Delay and Integration(TDI)의 오차에서 기인한다. 별을 점광원으로 본다면 점 퍼짐 함수를 정의하기 쉽고 Along/Across 방향을 동시에 측정 가능하다는 장점이 있다. 궤도상에서 별을 관측하는 것은 지상을 관측하는 것보다 대기 환경의 효과가 크지 않기 때문에 영상 품질 평가에 유리하다. Yaw Steering이나 Nadir Pointing과 같은 자세제어의 효과를 배제할 수 있으므로 자세제어의 효과가 상당 부분 제거된 영상품질을 분석할 수 있다. 지상관측시간이나 배터리 충전시간이 아닌 지구 본영에서 별을 관측하므로 임무에 방해받지 않는다. 지상관측과 같은 효과를 내고 TDI를 사용하는 환경을 구현하기위해 Line Rate를 고려한 자세 기동 방법에 대해 연구하였다. 큰 각도의 자세 기동이 예상되어 쿼터니안을 이용하여 Inertial Pointing하도록 자세 제어하였고, 자세 Slew Rate 구속조건 하에서 제어가 필요하다.

• 반도체디스플레이기술학회지
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• 제21권4호
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• pp.132-137
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• 2022

In this paper, we have studied the quadrature error reduction for the single drive 3-axis MEMS Gyroscope. There was a limitation of the previous study which is the z-axis quadrature error was large. To reduce this value, design methodologies were presented. And the methodologies included a different mesh application, z-rate spring structure change, and mass compensation for balancing of the structure. We conducted the modal analysis, drive mode analysis and sense mode analysis using COMSOL Multiphysics. As a result, a drive resonant frequency was 26003 Hz, with the x-sense, y-sense, z-sense being 26749 Hz, 26858 Hz, 26920 Hz, respectively. And the Mechanical sensitivity was computed at 2000 degrees per second(dps) input angular rate while the sensitivity for roll, pitch, and yaw was computed 0.011, 0.012, and 0.011 nm/dps respectively. And z-axis quadrature error was successfully improved, 2.78 nm to 0.95 nm, which the improvement rate was about 66 %.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.537-541
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• 2003

In order to control the missiles by aerodynamics, control surfaces sometime called fins are used. Deflection angles of these fins are the right control variables of the aerodynamics, but aerodynamicists prefer to use analytic variables called aileron, elevator and rudder instead of these physical variables, because these three analytic variables dominantly influence on the roll, pitch and yaw channels of the missile maneuver, respectively, and each can be assumed a linear combination of four fin deflection angles. On that basis, roll, pitch and yaw autopilots for controlling the attitudes or lateral acceleration of the missile are designed, and as a consequence outputs of each autopilot are aileron, elevator and rudder commands, respectively. In the existing fin control scheme for the typical tail-fin controlled cruciform missiles, firstly these outputs are distributed to four fin defection commands, and after that four fins are actuated by fin controllers so that their deflections follow the commands. This paper shows that performance of such control schemes can be degraded significantly when fin actuators have certain physical constraints such as slew rate, voltage or current limit, uncertainty of actuator dynamics, and so on, and propose a new control scheme which alleviates such problems. This scheme can be widely applied to various fin actuation systems. But in this paper, for convenience, tail-fin controlled cruciform missile is taken as an example, and it is shown that a proposed control scheme gives better performance than the existing one.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2007년도 추계학술대회 및 제23회 정기총회
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• pp.75-76
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• 2007

해난사고에 있어 운항자의 조선 실수가 큰 비중을 차지한다. 이는 항구의 여건이 크게 개선되지 않은 상태에서 선박이 점차 대형화 고속화, 그리고 항만의 물동량 증가에 따른 위험도의 증가라 볼 수 있으며, 이에 따라 연안에서의 선박의 충돌회피를 위한 자동제어에 관한 필요성이 대두되어 본 연구를 진행하였다. 본 연구는 MMG 수학모텔에 기반으로 Surge, Sway, Yaw 3자유도 운동방정식을 사용하였고, 충돌예상시점에 의한 정보(DCPA and TCPA) 를 이용하여 퍼지추론을 통한 위험도를 설정하였다. 이 방법의 설효성을 검증하기 위해 연안에서의 여러 정박지와 선박의 조우 상태에 따른 시뮬레이션을 수행하였다.

• 대한조선학회논문집
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• 제50권3호
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• pp.138-144
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• 2013

New experimental devices and methods to measure shaft forces of ships are proposed in this paper. The strain gauge type six-component load cell was newly designed and installed to the end of the propeller shaft. The signals generated from the sensor in the propeller rotating are transferred to the new data amplifying and processing board on the shaft and the data is transmitted to the self-made wireless receiver. To find out the characteristics of shaft forces during port and starboard turning motions in sea trial, oblique and combined yaw maneuvering tests at straight, transient, maximum yaw rate, steady conditions were performed with the model ship installed the shaft forces measuring device using circular motion tester of Samsung Ship Model Basin. Characteristics of the measured shaft forces in model tests show quantitatively good agreement with the computed values obtained by the CFD programs using the measured wake data in oblique towing conditions. In the near future, It is hoped that the estimated shaft forces for a ship from this experimental method could be validated through comparison with directly measured values of a ship.

• 한국운동역학회지
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• 제24권3호
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• pp.217-227
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• 2014

The purpose of this study was to investigate the relationship between distance and factors of javelin in korean male's javelin throwing. To accomplish this purpose, the analyzed trail selected total 29 trails (subjects 9) recorded more than 65 m in the 93rd National Sports Festival. The Kwon3D 3.1 version was used to obtain the three dimensional coordinates about the top, grip, end of javelin. And the kinematic data such as projection factors and direction angle of javelin calculated using Matlab2009a program. The statical analysis on the records (n=29) were used to Pearson's product moment correlation coefficient. There was a statistically positive relationship between the records and horizontal velocity (r=.866, ${\rho}$<.01), height (r=.541, ${\rho}$ <.001), height rate (r=.373, ${\rho}$ <.05) and horizontal displacement of javelin (r=.749, ${\rho}$ <.01), but the medial/lateral velocity showed a negative relationship to r=-.663 (${\rho}$ <.01). The attack and yaw angle showed not a significant relationship between the records, but the medial-lateral tilt (E1:r =-.557 [p<.01)] E2:r=-.629 [${\rho}$<.01], E3:r=-.528 [${\rho}$ <.01]) and attitude angle (E2:r=-.629 [[${\rho}$<.01], E3:r=-.619 [${\rho}$ <.01]) of javelin showed a negative relationship between the records, as well as the projection angle of javelin (r=-.419, ${\rho}$ <.05) showed a negative relationship between the records.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.937-943
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• 2017

To design an automatic steering controller with high performance for autonomous vehicle, it is necessary to have a precise model of the lateral dynamics with respect to the steering command input. This paper presents an empirical modeling of the steering system for an autonomous vehicle. The steering system here is represented by three individual transfer function models: a steering wheel actuator model from the steering command input to the steering angle of the shaft, a dynamic model between the steering angle and the yaw rate of the vehicle, and a dynamic model between the steering command and the lateral deviation of vehicle. These models are identified using frequency response data. Experiments were performed using a real vehicle. It is shown that the resulting identified models have been well fitted to the experimental data.

• International Journal of Ocean System Engineering
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• 제2권4호
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• pp.223-232
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• 2012

For the accurate estimation of the position and orientation of a UUV (unmanned underwater vehicle), a low-cost AHRS (attitude heading reference system) was developed using a low-cost IMU (inertial measurement unit) sensor which provides information on the 3D acceleration, 3D turning rate and 3D earth-magnetic field data in the object coordinate system. The main hardware system is composed of an IMU sensor (ADIS16405) and TMS320F28335, which is coded with an extended kalman filter algorithm with a 50-Hz sampling frequency. Through an experimental gimbal device, good estimation performance for the pitch, roll, and yaw angles of the developed AHRS was verified by comparing to those of a commercial AHRS called the MTi system. The experimental results are here presented and analyzed.

• 제어로봇시스템학회논문지
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• 제6권2호
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• pp.138-145
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• 2000

In this paper an initial alignment algorithm for a strapdown inertial navigation system is implemented using a RISC CPU board. The algorithm computes roll pitch and yaw angles of the direction cosine matrix utilizing measured components of the specific force and earth rate when the navigation system is stationary. The coarse alignment algorithm is performed first and then the fine alignment algorithm containing a 3rd-order gyrocompass loop follows. The experimental set consists of an IMU a CPU board and a monitoring system Experimental results show that the implemented algorithm can be utilized in navigation systems.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1103-1108
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• 2007

This paper describes a robust model-based roll state estimator for application to the detection of impending vehicle rollover. The roll state estimator is based on a 2-D bicycle model and a roll model to estimate the maneuver-induced vehicle roll motion. The measurement signals are lateral acceleration, yaw rate, steering angle, and vehicle speed. Vehicle mass is adapted to obtain robust performance of the estimator. Computer simulation is conducted to evaluate the proposed roll state estimator by using a validated vehicle simulator. It is shown that the roll state estimator shows robust performance without exact vehicle mass information.