• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.531-536
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• 2003

In this paper, a redesigned guidance and control system for a lunar lander is presented. In past studies, the authors developed a trajectory and attitude control system which achieves the vertical soft landing on the lunar surface. It is confirmed that the system has a good tracking ability to a predefined profile and good robustness against a thruster failure mode where a partial failure of clustered engines was assumed. However, under the previous control laws, the landing point tends to be shifted, in response to the system parameter values, from a target point. Also, an unbalanced moment due to a thruster failure mode was not considered in the simulation. Therefore, in this study, the downrange control is added to the system to enable the vehicle to land at a pre-assigned target point accurately. Furthermore, inhibiting the effect of the unbalanced moment is attempted thorough redesigning the attitude control system. A numerical simulation was performed to confirm the ability of the proposed system with regard to the above problems. Moreover, in the past simulations, a low initial altitude was assumed as an initial condition: in this study, however, the performance of the proposed system is examined over the whole trajectory from an initial altitude of 10 [km] to the lunar surface.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1998년도 Proceedings of International Symposium on Remote Sensing
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• pp.149-152
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• 1998

Nowadays, GIS, as multi-discipline information system, is closely linked with GPS application in conjunction with GIS-T or Logistics GIS. With this R&D trend. CPS/GIS application system for AVL is newly developed in this study. This AVL is designed and implemented by using pure Java computing technology towards com ing Car-equipped wireless Internet PC age, and main features of Java are included at this system: Platform independence, Multi-thread processing, and Object-oriented paradigm. While, because core modules of this AVL are based on GIS spatial engine, unlike other commercial AVLs, large spatial database problem handling digital image/spatial information and attribute information and direct access problem of GIS data is easily dealt with. this system can directly access external database by using JDBC: MS Access for desktop version and Oracle for W/S version. Finally, it is thought that Java-based AVL, one of CPS/CIS applications, can be easily extended into other prospective GIS applications: Land surveyor supporting system, Flight tracking system, 3D facility management system with CPS, and so forth.

• 반도체디스플레이기술학회지
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• 제22권2호
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• pp.112-119
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• 2023

In urban environments, signals of Global Positioning System (GPS) can be blocked and reflected by tall buildings, large vehicles, and complex components of road network. Therefore, the performance of the positioning system using the GPS module in urban areas can be degraded due to the loss of GPS signals necessary for the position estimation. To deal with this issue, various localization schemes using inertial measurement unit (IMU) sensors, such as gyroscope and accelerometer, and Bayesian filters, such as Kalman filter (KF) and particle filter (PF), have been designed to enhance the performance of the GPS-based positioning system. Among Bayesian filters, the PF has been widely used for the target tracking and vehicle navigation, since it can provide superior performance in estimating the state of a dynamic system under nonlinear/non-Gaussian circumstance. This paper presents a positioning system that uses the double-stacked particle filter (DSPF) as well as the accelerometer, gyroscope, and GPS receiver on the smartphone to provide higher pedestrian positioning accuracy in urban environments. The DSPF employs a nonparametric technique (Parzen-window) to create the multimodal target distribution that approximates the posterior distribution. Experimental results show that the DSPF-based positioning system can provide the significant improvement of the pedestrian position estimation in urban environments.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2001년도 추계학술대회 논문집
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• pp.91-96
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• 2001

This paper presents a neural net based nonlinear adaptive controller for an autonomous underwater vehicle (AUV). AUV's dynamics are highly nonlinear and their hydrodynamic coefficients vary with different operational conditions, so it is necessary for the high performance control system of an AUV to have the capacities of learning and adapting to the change of the AUV's dynamics. In this paper a linearly parameterized neural network is used to approximate the uncertainties of the AUV's dynamics, and a sliding mode control is introduced to attenuate the effects of the neural network's reconstruction errors and the disturbances of AUV's dynamics. The presented controller is consist of three parallel schemes; linear feedback control, sliding mode control and neural network. Lyapunov theory is used to guarantee the asymptotic convergence of trajectory tracking errors and the neural network's weights errors. Numerical simulations for motion control of an AUV are performed to illustrate to effectiveness of the proposed techniques.

• 대한교통학회지
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• 제27권2호
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• pp.207-214
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• 2009

최근 각종 센서 및 통신기술의 발달은 과거에 비해 보다 미시적이고 폭넓은 교통자료의 수집과 운전자의 주행편의를 위한 다양한 방식의 정보제공을 실시간 환경에서 가능하도록 하였다. 본 연구에서는 Positive Guidance 기법을 응용하여 이와 같은 실시간 환경에서 적용 가능한 실시간 교통상충 분석 기반의 경고정보 제공 방안을 제안하고자 한다. 제안하는 시스템은 영상 이미지 추적 기법으로 개별차량의 주행패턴을 분석하여 인접 차량간 상충을 분석하고, ARIMA 모형을 이용하여 상충분석결과를 바탕으로 영상검지영역의 위험도를 예측한다. 위험도 예측을 통해 생성된 경고정보는 Positive Guidance 기법을 적용하여 영상검지영역 상류부에서 접근 중인 운전자에게 제공된다. 본 연구의 성과물은 향후 보다 교통사고 예방을 위한 보다 진보된 교통정보시스템의 개발 시 유용하게 활용될 것으로 기대된다.

• 대한전자공학회논문지TC
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• 제43권9호
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• pp.69-79
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• 2006

영상 정보를 이용한 교통 모니터링 시스템에 관한 많은 연구가 이루어졌다. 대부분의 교통 모니터링 기술은 전체 영상을 분석하는 기법과 국부 영역을 검사하는 기법으로 구분된다. 하지만, 제안된 대부분의 기법들은 동작 환경이 변화할 경우 강건성의 결여로 인해 성능이 급격히 저하하는 문제점을 갖고 있다. 본 논문에서는 기존의 논문에서 제안되었던 다양한 기법들의 특성을 조사하고, 장점과 단점을 분석한다. 또한 각 응용 분야마다 영상 처리를 이용하는 기법들이 가지고 있는 문제점들을 해결 할 수 있는 적절한 방법을 고찰한다.

• 제어로봇시스템학회논문지
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• 제22권8호
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• pp.633-642
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• 2016

It is important for advanced active safety systems and autonomous driving cars to get the accurate estimates of the nearby vehicles in order to increase their safety and performance. This paper proposes a sensor fusion method for radar and vision sensors to accurately estimate the state of the preceding vehicles. In particular, we performed a study on compensating for the lateral state error on automotive radar sensors by using a vision sensor. The proposed method is based on the Interactive Multiple Model(IMM) algorithm, which stochastically integrates the multiple Kalman Filters with the multiple models depending on lateral-compensation mode and radar-single sensor mode. In addition, a Probabilistic Data Association Filter(PDAF) is utilized as a data association method to improve the reliability of the estimates under a cluttered radar environment. A two-step correction method is used in the Kalman filter, which efficiently associates both the radar and vision measurements into single state estimates. Finally, the proposed method is validated through off-line simulations using measurements obtained from a field test in an actual road environment.

• 한국산업정보학회논문지
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• 제24권4호
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• pp.21-28
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• 2019

ICT 기술이 발전함에 따라 교통사고 발생시 ICT기술을 활용하여 신속하게 처리하기 위한 연락체계 구축에 관한 연구가 활발히 진행 중이다. e-Call(Emergency call)은 교통사고를 인식하고 신고가 이루어지는 차량ICT기반 긴급구난체계를 말한다. 한편, 기존의 버스정보시스템은 버스에 장착된 위치추적시스템을 통해 측위 데이터를 수집하여 센터로 전송한 후 센터에서는 수집된 버스의 운행정보를 기반으로 다양한 서비스를 제공하고 있다. 본 논문에서는 대중버스에서 사고, 고장, 긴급상황이 발생했을 때 이를 신속하게 처리하기 위하여, 기존의 버스정보시스템을 활용한 긴급구난체계를 설계하고 구현하였다.

• 센서학회지
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• 제28권3호
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• pp.164-170
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• 2019

In this paper, a lane detection and tracking algorithm based on vision sensors and employing a robust filter for inner edge detection is proposed for developing a lane departure warning system (LDWS). The lateral offset value was precisely calculated by applying the proposed filter for inner edge detection in the region of interest. The proposed algorithm was subsequently compared with an existing algorithm having lateral offset-based warning alarm occurrence time, and an average error of approximately 15ms was observed. Tests were also conducted to verify whether a warning alarm is generated when a driver departs from a lane, and an average accuracy of approximately 94% was observed. Additionally, the proposed LDWS was implemented as an embedded system, mounted on a test vehicle, and was made to travel for approximately 100km for obtaining experimental results. Obtained results indicate that the average lane detection rates at day time and night time are approximately 97% and 96%, respectively. Furthermore, the processing time of the embedded system is found to be approximately 12fps.

• 한국해양공학회지
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• 제17권6호
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• pp.83-90
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• 2003

This paper presents an underwater hybrid navigation system for a semi-autonomous underwater vehicle (SAUV). The navigation system consists of an inertial measurement unit (IMU), and a Doppler velocity log (DVL), accompanied by a magnetic compass. The errors of inertial measurement units increase with time, due to the bias errors of gyros and accelerometers. A navigational system model is derived, to include the scale effect and bias errors of the DVL, of which the state equation composed of the navigation states and sensor parameters is 20. The conventional extended Kalman filter was used to propagate the error covariance, update the measurement errors, and correct the state equation when the measurements are available. Simulation was performed with the 6-d.o,f equations of motion of SAUV, using a lawn-mowing survey mode. The hybrid underwater navigation system shows good tracking performance, by updating the error covariance and correcting the system's states with the measurement errors from a DVL, a magnetic compass, and a depth sensor. The error of the estimated position still slowly drifts in the horizontal plane, about 3.5m for 500 seconds, which could be eliminated with the help of additional USBL information.