• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.1303-1306
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• 2005

무선 센서 네트워크는 저가의 많은 노드들로 구성되어 있으며. 이 노드들은 정보수집, 계산, 통신을 위한 전력등을 가지고 있다. 센서 네크워크에서의 보안을 위하여 주로 암호화 방법이 사용되고 있으나 자원이 제약적인 센서 네크워크에서 많은 에너지와 계산을 필요로 하는 암호화 방법은 센서 노드의 수명을 단축시킨다. 이를 보완하기 위하여 본 논문에서는 위치정보 은닉을 이용한 저전력 보안방법을 제안한다. 제안된 방법에서는 위치정보의 은닉을 위하여 상대거리정보를 사용하며, 센서 노드간 통신에서는 상대좌표로부터 구할 수 있는 노드사이의 상대거리정보가 사용된다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.6
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• pp.1357-1363
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• 1994

A Monte-Carlo simulation model is developed to predict size distribution produced by the coalescence of air bubbles in turbulent shear f1ow. The simulation consists of generating a population of air bubbles into the initial positions at each time step and tracking them by simulating motions and checking collisions. The radial displacement of air bubbles in the simulation model is produced by numerically solving an advective diffusion equation. Longitudinal displacements are generated from the logarithmic flow velovity distribution and the bubble rise velocity. Collision of air bubbles for each time step is detected by a geometric test using their relative positions at the beginning of the time step and relative displacements during the time step. At the end of the time step, the total number of bubbles, their positions, and sizes are updated. The computer program is coded such that minimum storages for sizes and positions of bubbles are required.

• Journal of KIISE:Computing Practices and Letters
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• v.5 no.2
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• pp.273-282
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• 1999

범국가적으로 지리정보시스템(GIS : Geographic Information System) 구축작업이 활성화되고 있는가운데 정부에서는 국가정보화 기반조성 차원에서 전국에 걸친 국가기본도 수치지도화 사업을 추진하고 있다. 국가기본도는 설비관리용 GIS를 구축하려는 국내 각 수요기관에서 활용되어져 GIS DB구축작업이 용이해질 것으로 예상되지만, 국가기본도에서는 각 기관에서 관리하고자 하는 모든 설비정보가 포함되어 있는 것은 아니므로 세부적인 관리대상설비의 추가 입력작업이 필요하다. 설비정보 입력은 대체적으로 각 기관에서 자체 보유하고 있는 설비도면을 기준으로 수행되지만 국가기본도와 설비도 간에는 기초 도면에 다름에 따른 설비위치 상대오차가 발생된다. 국가기본도 사용을 전제할 때 이러한 문제점은 피할수 없는 현상이며, 상대위치를 보정시키면서 관리대상 설비를 입력하려면 많은 예산과 인력이 소요될것으로 예상된다. 배전설비관리 GIS를 구축하고자 하는 한전에서는 이를 효과적으로 해결하고자 기초도면 변경에 따른 설비위치 자동보정기법을 연구하여 이를 기반으로한 시스템 개발을 완료하였다. 개발된 시스템의 정확도 및 실용화 가능성을 확인하기 위해 설비위치의 기준이 되는 전력주를 대상으로 샘플지역을 선정하여 자동보정을 실시하였으며, 현장실사를 통한 검증을 실시한 결과 약 94.6%에 달하는 보정 결과 만족도를 얻을 수 있었다.

• Journal of Drive and Control
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• v.17 no.4
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• pp.8-14
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• 2020

Intelligent devices using ICT technology have been introduced in the field of construction machinery to improve productivity and stability. Among the intelligent devices, Machine Guidance is a device that provides real-time posture, location, and work range to drivers by installing various sensors, controllers, and satellite navigation systems on construction machines. Conversely, the efficiency of equipment that requires location information, such as machine guidance, will be greatly reduced in buildings, and tunnels in the GPS blind spots. Thus, the other high-precision positioning technologies are required in the GPS blind spot zone. In this study, we will develop a relative position measurement system that provides precise location information such as construction machinery and robots in a local area where the GPS reception is difficult. A relative position measurement system tracks a marker in the form of a sphere installed on a vehicle by using the image base tracking technology, and measures the distance and direction information to the marker to calculate a position.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.12
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• pp.1445-1452
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• 2013

In this paper, we propose a real-time algorithm for estimating the relative position of a person with respect to a robot (camera) using a monocular camera. The algorithm detects the head and shoulder regions of a person using HOG (Histogram of Oriented Gradient) feature vectors and an SVM (Support Vector Machine) classifier. The size and location of the detected area are used for calculating the relative distance and angle between the person and the camera on a robot. To increase the speed of the algorithm, we use a GPU and NVIDIA's CUDA library; the resulting algorithm speed is ~ 15 Hz. The accuracy of the algorithm is compared with the output of a SICK laser scanner.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.11
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• pp.795-802
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• 2019

This paper deals with position-attitude coupling motion during spacecraft relative operation, and suggests dual quaternion-based kinematics for the problem. The position-attitude coupling motion can occur when the target point is located at an arbitrary point on the satellite body, not the center of mass. This is especially apparent in close proximity operation case. The dual quaternion-based kinematics directly reflects the angular velocity state, so that the coupling motion in which the change of attitude affects the position can be concisely defined. In this study, a new dual quaternion-based kinematics is presented along with a conventional approach to solve the coupling problem. Numerical simulations show that the position error for the target point is generated by the coupling motion, and verify that the dual quaternion-based kinematics can solve this problem.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.3
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• pp.219-229
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• 2018

This paper proposes Kalman Filter-based relative navigation algorithms for proximity tasks such as rendezvous/docking/cluster-operation of spacecraft using PSD Sensors and Infrared Beacon Modules. Numerical simulations are performed for comparative analysis of the performance of each relative-navigation technique. Based on the operation principle and optical modeling of the PSD Sensor and the Infrared Beacon Module used in the relative navigation algorithm, a measurement model for the Kalman filter is constructed. The Extended Kalman Filter(EKF) and the Unscented Kalman Filter(UKF) are used as probabilistic relative navigation based on measurement fusion to utilize kinematics and dynamics information on translational and rotation motions of satellites. Relative position and relative attitude estimation performance of two filters is compared. Especially, through the simulation of various scenarios, performance changes are also investigated depending on the number of PSD Sensors and IR Beacons in target and chaser satellites.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.12
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• pp.2520-2527
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• 2015

Position information is important to carry out military operations. In general, GPS is used to estimate position. However, GPS is vulnerable to jamming due to the low received signal strength, therefore GPS can be easily jammed. The relative navigation is an auxiliary navigation system defined in JTIDS. When GPS is jammed, the relative navigation requires ground reference units on the ground to operate accurately. If the ground reference unit does not exist, nodes operated by the relative navigation depend on the inertial navigation system to identify their position. However, this positioning scheme based on only INS causes accumulative position error, therefore the nodes cannot identify their position accurately for a long time. In this paper, we propose an alternative to reduce position error generated by depending inertial navigation system. In order to verify that the performance of proposed scheme is better than that of the existing scheme, various simulations are conducted.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.1
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• pp.89-98
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• 2011

In this paper, a new touch user interface which is based on the hand operations of dragging and diversion is presented. With it, convenience and quickness for inputting of texts as well as searching and selecting of multi-layered menus are improved. The new interface also applies relative coordinate systems which display texts on the touch positions corresponding to the moving of touch location. It accommodates more text codes than those in conventional fixed coordinate systems which allocates texts to fixed location on touch screen. The suggested interface is implemented to IPTV remote control and set-top box to prove its practicality and effectiveness.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.9
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• pp.889-895
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• 2011

In recent days, some techniques to prevent from radar detection have been applied on aircraft system. RWR(Radar Warning Receiver) can be used for estimating the source location of the aircraft which emits radar pulse. Current existing method of localizing radar pulse emission source is using AOA(Angle Of Arrival) and most techniques are focused on finding exact AOA to find exact location. In this case, however, the exact AOA does not always result in finding exact source location while target aircraft is moving fast. In this paper, a localization method using the phase delay of the radar pulse's low frequency applies and so a scanning method for the interest area does in order to estimate exact source location by using phase delay.