• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.529-534
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• 2006

New geocentric geodetic datum has recently been realized in Korea, Korean Geodetic Datum 2002- KGD2002, to overcome problems due to the existing Tokyo datum, which had been used in this country since early 20th century. This transition will support modern surveying techniques, such as Global Navigation Satellite Systems (GNSS) and ensures that spatial data is compatible with other international systems. For this realization, very long baseline interferometry (VLBI) observations were initially carried out in 1995 to determine the coordinates of the origin of KGD2002 based on the International Terrestrial Reference Frame (ITRF). Continuous GPS observations were collected from 14 reference stations across Korea to compute the coordinates of 1st order horizontal geodetic control points. During the campaign, GPS observations were also collected at about 9,000 existing geodetic control points. In 2006, network adjustment with all data obtained using GPS and EDM since 1975 has been performed under the condition of fixing the coordinates of GPS continuous observation stations to compute coordinate measurements of the 2nd and 3rd geodetic control points. This paper describes the GPS campaigns which have been undertaken since 1996 and details of the network adjustment schemes. This is followed

• 예술인문사회 융합 멀티미디어 논문지
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• 제8권3호
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• pp.467-475
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• 2018

최근 전 세계적으로 지진의 발생이 증가하고 있으며, 우리나라는 2016년 9월 12일 경주지역에서 지진 관측 시작 이후 가장 큰 리히터 규모 5.8의 지진이 발생하였다. 또한 이 지진발생 이후 2017년 1월~2017년 12월까지 약 200회가 넘는 여진이 발생하고 있다. 2017년 발생한 지진 중 가장 큰 규모의 지진은 2017년 11월 15일 포항 인근에서 발생한 5.4 규모의 지진이었다. 본 연구에서는 국내 상시관측소 데이터를 이용하여 지진으로 인한 좌표변동을 분석하고자 하였다. 2017년 11월 15일 발생한 포항지역 지진으로 인한 좌표변화 분석을 위해 이동측위 방법으로 자료처리를 수행하였으며, 2017년 1월~2017년 12월까지 국내 상시관측소 9개소의 관측자료를 상대측위 방법으로 처리하여 지진으로 인한 좌표변화를 분석하였다. 연구결과, 이동측위를 통해 지진으로 인한 순간적인 좌표변화량을 추정할 수 있었으며, 상대측위 결과로부터 국내 상시관측소의 좌표변화가 없음을 제시할 수 있었다. 2017년 경주지진 이후 계속해서 여진이 발생하고 있어 이 지역에 대한 지속적인 모니터링이 필요할 것으로 판단된다.

• The Journal of the Acoustical Society of Korea
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• 제17권2E호
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• pp.53-58
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• 1998

In this paper, we study the response of several anisotropic systems to buried transient line loads. The problem is mathematically formulated based on the equations of motion in the constitutive relations. The load is in form of a normal stress acting with arbitrary axis on the plane of monoclinic symmetry. Plane wave equation is coupled with vertical shear wave, longitudinal wave and horizontal shear wave. We first considered the equation of motion in reference coordinate system, where the line load is coincident with symmetry axis of the orthotrioic material. Then the equation of motion is transformed with respect to general coordiante system with azimuthal angle by using transformation tensor. The load is first described as a body force in the equations of the motion for the infinite media and then it is mathematically characterized. Subsequently the results for semi-infinite spaces is also obtained by using superposition of the infinite medium solution together with a scattered solution from the free surface. Consequently explicit solutions for the displacements are obtained by using Cargniard-DeHoop contour. Numerical results which are drawn from concrete examples of orthotropic material belonging to monoclinic symmetry are demonstrated.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2003년도 추계학술발표회 논문집
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• pp.423-431
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• 2003

This study presents on generation coefficients of the RFM using GEO-level stereo images of the IKONOS satellite. 3-D positioning and DEM generation of this model on the test field. In result, the maximum error of image coordinates acquired by the upward transform of the RFM did nat exceed 8 pixels. DEM was generated with kriging interpolation extracted three dimensional ground coordinate to rational quadratic function form, me compared it to reference digital elevation model made from 1:5,000 digital map and 1:1,000 digital map, and so, could generate digital elevation model in the accuracy as average RMSE of elevation was ${\pm}$ 3∼5 m in RFM.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2004년도 춘계학술발표회논문집
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• pp.177-182
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• 2004

This study presents the application of aerial photographs and KOMPSAT-1 Electro-Optical Camera(EOC) imagery in detecting the change of an urban area that has been rapidly growing. For the study, we used multi-time images which were acquired by two different sensors. For all of the images, the coordinate reference system and scale were first made identical through the 1st and 2nd geometric corrections and then image resampling were carried out to spatial resolution of 7m to detect changes under the same conditions. The Image Differencing was employed as a change detection technique. It was confirmed to be able to detect the changes of terrestrial surface like building, structure and road features from aerial photos and KOMPSAT EOC images with single band. The changes could be detected to some extent with the images acquired from different kinds of sensors as well as the same kinds of sensors.

• 한국해양공학회지
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• 제26권3호
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• pp.6-12
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• 2012

In this paper, addressed is the control problem of generating a formation for a group of unmanned surface and underwater vehicles. The formation control scheme proposed in this work is based on a fusion of theleader-follower and virtual reference approaches. This scheme gives a formation constraint representation that is independent of the number of vehicles in the formation and the resulting control algorithm is scalable. One of the most important features in controller design is the ability of the controller to globally and exponentially stabilize the formation errors defined by the formation constraints. The proposed controller is based on feedback linearization, and the formation errors are shown to be globally and exponentially stable in the sense of Lyapunov.

• 제어로봇시스템학회논문지
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• 제19권3호
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• pp.240-247
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• 2013

This paper proposes an optimal three-dimensional coordinate implementation of the vision sensor using two CCD cameras. The PBVS (Position based visual servoing) is implemented using the positional information obtained from images. Stereo vision by PBVS method that has enhanced every frame using calibration parameters is effective in the distance calculation. The IBVS (Image based visual servoing) is also implemented using the difference between reference and obtained images. Stereo vision by IBVS method calculates the distance using rotation angle of motors that correspond eyes and neck without enhanced images. The PBVS method is compared with the IBVS method in terms of advantages, disadvantages, computing time, and performances. Finally, the IBVS method is applied for the dual arm manipulator on the mobile inverted pendulum. The autonomous mobile inverted pendulum is successfully demonstrated using the center of the manipulator's mass.

• Journal of Power Electronics
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• 제15권3호
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• pp.796-805
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• 2015

New direct and indirect current control methods for a fault-tolerant active power filter topology are presented in this paper. Since a three-phase four-switch topology has a phase bridge current which cannot be directly controlled, a hysteresis control method in the α-β plane which controls the three-phase current in the two-phase stationary coordinate system is proposed. The improved SVPWM algorithm is able to eliminate the operation of the trigonometric functions in the traditional algorithm by rotating the α-β coordinates and alternating the sequence of the output vectors, which in turn simplifies the algorithm and reduces the switching frequency. The selection of the DC-side reference voltage and DC-side capacitor equalization strategy are also discussed. Simulation and experiments demonstrate that the proposed control method is correct and feasible.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.20-23
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• 1996

This paper deals with the flexible manipulator with rotational and translational degrees of freedom, which has an arm of time-varying length with the prismatic joint. The tracking control problem of the flexible manipulator is considered. First we design the controller of the 2-type robust servo system based on the finite horizon optimal control theory for the trajectory planned as a discontinuous velocity. Next, to reduce the tracking error, we use the method of the dynamic programming and of modifying the reference trajectory in time coordinate. The simulation results show that the dynamic modeling is adequate and that the asymptotic stabilization of the flexible manipulator is preserved in spite of nonlinear terms. The PTP control error has been reduced to zero completely, and the trajectory tracking errors are reduced sufficiently by the proposed control method.

• 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.