• Proceedings of the KAIS Fall Conference
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• 2008.05a
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• pp.258-260
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• 2008

본 논문에서 다중경로 전파환경에서 전파특성을 연구하였다. 목표지점에서 전계의 세기는 직접파와 지면 반사파의 합으로 구성된다. 이 논문에서는 지면의 반사를 고려하여 목표물 근처 공간의 3차원 전계분포를 계산하는 프로그램을 개발하였다. 실제 목표물의 궤적에 따라 목표물의 수신기에서의 신호세기를 예측하는 3차원 모델을 개발 하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2202-2209
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• 2009

Joint paths are induced mathematically for many kinds of joint pattern between master- and sub-pipes. By compensating them with root gap of welds and kerf width, real cutting paths are determined. Their NC codes are generated, and the paths generated by NC code are verified by a ghost function. A beveling is implemented through tilting a torch in the A- and B-axis direction for 8 sections in the chuck rotation of C-axis. The effective CAM program was developed specially for 6-axis CNC pipe coasters which cut a master or sub- pipe along the cutting path and simultaneously fulfill a beveling process.

• KIISE Transactions on Computing Practices
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• v.22 no.4
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• pp.189-194
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• 2016

A trajectory is the motion path of a moving object. The advances in IT have made it possible to collect an immeasurable amount of various type of trajectory data from a moving object using location detection devices like GPS. The trajectories of moving objects are widely used in many different fields of research, including the geographic information system (GIS) field. In the GIS field, several attempts have been made to automatically generate digital maps of roads by using the vehicle trajectory data. To achieve this goal, the method to cluster the trajectories on the same road is needed. Usually, the $Fr{\acute{e}}chet$ distance measure is used to calculate the distance between a pair of trajectories. However, the $Fr{\acute{e}}chet$ distance measure requires prolonged calculation time for a large amount of trajectories. In this paper, we presented a fast heuristic algorithm to distinguish whether the trajectories are in close distance or not using the discrete $Fr{\acute{e}}chet$ distance measure. This algorithm trades the accuracy of the resulting distance with decreased calculation time. By experiments, we showed that the algorithm could distinguish between the trajectory within 10 meters and the distant trajectory with 95% accuracy and, at worst, 65% of calculation reduction, as compared with the discrete $Fr{\acute{e}}chet$ distance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3066-3073
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• 2009

Joint paths of master and branch pipes are induced mathematically for many kinds of joint patterns between both pipes in 3-axis pipe profile-cutting machines. By compensating them with a kerf width, the real cutting paths are determined, and their CL-data are generated, and the tool paths generated by CL-data are verified by a ghost function. A bevelling of welds is implemented through tilting a cutting torch in the $\beta$-axis direction for 8 sections in the chuck rotation of $\alpha$-axis. A PLC controls simultaneously position and velocity in a real time for $\alpha$, X, $\beta$-axis by loading CL-data generated. We developed the PLC-controlled 3-axis pipe profile-cutting system which can cut a master or branch pipe along the cutting path and simultaneously do a bevelling process.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.6
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• pp.53-61
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• 2014

For monitoring the flight trajectory and the status of a launch vehicle, the mission control system in NARO space center process data acquired from the ground tracking system, which consists of two tracking radars, four telemetry stations, and one electro-optical tracking system. Each tracking unit exhibits its own tracking error mainly due to multi-path, clutter and radio refraction, and by utilizing only one among transmitted informations, it is not possible to determine the actual vehicle trajectory. This paper presents a way of generating flight trajectory via post-processing the data received from the ground tracking system. The post-processing algorithm is divided into two parts: compensation for atmosphere radio refraction and multi-sensor fusion, for which a decentralized Kalman filter was adopted and implemented based on constant acceleration model. Applications of the present scheme to real data resulted in the flight trajectory where the tracking errors were minimized than done by any one sensor.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.2
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• pp.150-159
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• 2010

The approach and landing phase of a re-entry vehicle is composed of Steep Glideslope phase, Circular Flare phase, Flare Maneuver phase. The trajectory planning algorithm with geometric parameters is studied in this paper for on-board trajectory planning. This algorithm generate reference trajectory rapidly considering safe landing of re-entry vehicle. In this paper, the Mamdani Fuzzy PD type controller for longitudinal and lateral control is designed which has robustness of nonlinear system. In addition, the simulation is performed including initial downrange and crossrange errors, and the results shows that the proposed fuzzy logic controller has good performance.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.11a
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• pp.71-72
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• 2019

최근 공공안전 분야에서는 국민의 위험상황을 분석하여 선제적으로 예측을 하여 국민의 안전을 보장하기 위한 요구사항이 대두대고 있다. 또한 스마트폰 및 스마트워치와 같은 고성능 모바일 단말 기기들의 대중화로 인해 해당 기기들에 부착된 다양한 센서 데이터들을 융복합하여 분석할 경우, 수집한 센서 데이터의 잠재적 가치를 안전보장 측면에서 사용할 수 있는 장점이 있다. 본 논문에서는 대인, 대물, 장소에 해당하는 로그 데이터들을 융복합 분석하여 보호대상자의 안전을 지원하는 다중로그 플랫폼 기반 이동경로 분석 기법을 제안한다. 다중로그 플랫폼에서 수집하는 보호대상자의 이동 경로 궤적을 활용하여 과거에 축적된 이동경로 패턴과 비교를 통해 현재 경로가 평소에 이용하던 경로와의 유사도를 추천하게 된다. 해당 이동 경로 분석 시스템은 위치기반 멀티모달 센서 데이터를 융복합 하여 보호대상자의 안전을 보장하는데 기여 할 것으로 예상된다.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.11-14
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• 2005

이동 객체 데이터베이스에서 위치 불확실성은 이동 객체의 고유한 성질 중 하나이다. 이것은 모델링과 질의 처리 및 질의 결과에 예상치 못한 문제들을 야기시키기 때문에 이를 해결하기 위해 많은 연구들이 진행되어 왔다. 이전의 연구들은 객체의 최근 속력과 방향 정보를 사용하여 불확실한 객체의 위치를 추정하였다. 이 방법은 추정이 간단하고 가까운 미래의 위치와 시간 추정에는 유용하지만 계획된 경로를 가진 미래의 먼 위치와 시간의 추정에는 적합하지 않다. 따라서, 이 논문에서는 계획된 경로를 가진 이동객체의 미래의 불확실한 시간을 추정하는 방법을 제안한다. 계획된 경로를 이동하는 객체일지라도 기계적인 오류와 예기치 못한 상황들로 인하여 실제 객체의 위치와 계획된 경로는 정확히 일치 하지는 않는다. 그렇지만 객체의 위치는 계획된 경로에 근접하여 위치할 확률이 가장 높으므로 우리는 계획된 경로에 객체의 궤적을 투영시킨다. 또한 미래의 시간을 추정을 위하여 웹사이트에서 제공하는 차량의 평균속도를 사용한다. 제공된 평균 속도는 일반 차량의 평균 속도이므로 우리는 이를 가공하여 미래 시간을 추정한다.

• Journal of the HCI Society of Korea
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• v.5 no.2
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• pp.15-24
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• 2010

A Digilog Book is an augmented reality (AR) based next generation publication supporting both sentimental analog emotions and digitized multi-sensory feedbacks by combining a conventional printed book and digital contents. As a Digilog Book authoring software, ARtalet provides an intuitive authoring environment through 3D user interface in AR environment. In this paper, we suggest ARtalet authoring environment based trajectory editing method to generate and manipulate a movement path of an augmented 3D object on the Digilog Book. Specifically, the translation points of the 3D manipulation prop is examined to determine that the point is a proper control point of a trajectory. Then the interpolation using splines is conducted to reconstruct the trajectory with smoothed form. The dynamic score based selection method is also exploited to effectively select small and dense control points of the trajectory. In an experimental evaluation our method took the same time and generated a similar amount of errors as the usual approach, but reduced the number of control points needed by over 90%. The reduced number of control points can properly reconstruct a movement path and drastically decrease the number of control point selections required for movement path modification. For control manipulation, the task completion time was reduced and there was less hand movement needed than with conventional method. Our method can be applicable to drawing or curve editing method in immersive In-Situ AR based education, game, design, animation, simulation application domains.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.1
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• pp.215-222
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• 2017

An active synthetic aperture sonar mounted on small UUV is generated various trajectory disturbances in the traveling path by the influence of external underwater environments. That is the phase mismatch occurs in the synthetic aperture processing of the signals reflected from seabed objects and fetches the detection performance decreases. In this paper, we compensated deteriorated images by the active SAS autofocus processing using DPC and analyzed the effects of detection performance when the periodic trajectory disturbances occur in the side direction at a constant velocity and straight movement of UUV. Through simulations, the deteriorated images according to the periodic disturbance magnitudes and period variations in the platform were compensated using difference phases processing of the overlapping displaced phase centers on the adjacent transmitted ping signals, and we conformed the improved performance characteristics of azimuth resolution and detection images at 3dB reference point.