• 정보과학회 논문지
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• 제43권12호
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• pp.1315-1324
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• 2016

최근 드론에 대한 관심이 증가하면서, 드론을 활용한 다양한 기술들이 선보이고 있다. 특히, 다수의 드론을 통한 군집 비행의 기술은 협업을 통한 복잡한 임무 수행이 가능하여 빠른 시간안에 임무를 완수할 수 있어 다양한 분야에서 각광을 받고 있다. 하지만 실외의 경우 GPS의 정밀도가 낮아 정밀 비행이 어렵기 때문에 고정밀 위치 인식이 필요한 임무에는 적합하지 않다. 뿐만 아니라, 실외에서 다수의 비행체를 좁은 공간에서 동시 정밀 제어하다보니, 정밀 위치 예측이 어려운 경우 충돌이 발생하는 심각한 문제를 초래할 수 있다. 본 논문에서는 RTK-GPS(Real-Time Kinematic-GPS)를 포함한 다수 센서를 활용하여 위치 정밀도를 증가시키고, 센서 오류로 인한 문제를 최소화하기 위해 제안한 모드 스위칭 기법에 대해 설명한다. 그리고 이를 기반으로 개발한 실외 군집 비행 시스템에 대해서도 소개한다.

• IEIE Transactions on Smart Processing and Computing
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• 제2권2호
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• pp.45-56
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• 2013

The precise identification of vehicle positions, known as the vehicle localization problem, is an important requirement for building intelligent vehicle ad-hoc networks (VANETs). To solve this problem, two categories of solutions are proposed: stand-alone and data fusion approaches. Compared to stand-alone approaches, which use single information including the global positioning system (GPS) and sensor-based navigation systems with differential corrections, data fusion approaches analyze the position information of several vehicles from GPS and sensor-based navigation systems, etc. Therefore, data fusion approaches show high accuracy. With the position information on a set of vehicles in the preprocessing stage, data fusion approaches is used to estimate the precise vehicular location in the local map building stage. This paper proposes an efficient local map building scheme, which increases the accuracy of the estimated vehicle positions via V2V communications. Even under the low ratio of vehicles with communication modules on the road, the proposed local map building scheme showed high accuracy when estimating the vehicle positions. From the experimental results based on the parameters of the practical vehicular environments, the accuracy of the proposed localization system approached the single lane-level.

• Journal of Power Electronics
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• 제16권4호
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• pp.1621-1628
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• 2016

Experiencing power declines when the secondary coil is at the middle position between two primary coils is a serious problem in segmented on-road charging systems with a single energized segmented primary coil. In this paper, the topological transformation of a primary circuit and a hierarchical compensation capacitor control are proposed. Firstly, the corresponding compensation capacitors and receiving powers of different primary structures are deduced under the condition of a fixed frequency. Then the receiving power characteristics as a function of the position variations in systems with a single energized segmented primary coil and those with double segmented primary coils are analyzed comparatively. A topological transformation of the primary circuit and hierarchical compensation capacitor control are further introduced to solve the foregoing problem. Finally, an experimental prototype with the proposed topological transformation and hierarchical compensation capacitor control is carried out. Measured results show that the receiving power is a lot more stable in the movement of the secondary coil. It is a remarkable fact that the receiving power rises from 10.8W to 19.2W at the middle position between the two primary coils. The experimental are in agreement with the theoretical analysis.

• 한국측량학회지
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• 제14권2호
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• pp.167-179
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• 1996

AFM은 반송파 위상을 이용하는 GPS 정밀측위에서 일반적으로 문제가 되는 초기미지정수와 cycle-slip에 영향을 받지 않는 기법이다. 그러나 기존의 AFM알고리즘에는 두 가지의 어려움이 있다. 첫째, 최적의 수신기 위치를 구하기 위한 계산시간이 너무 길다는 점이다. 둘째, 검색공간 내에 최적의 수신기 위치로 선정이 가능한 후보가 많을 수 있다는 점이다. 따라서 기존의 AFM 알고리즘이 갖는 단점을 개선하여 OTF의 환경에 적용할 수 있도록 계산시간을 획기적으로 단축시키는 새로운 알고리즘이 본 논문에서 제시되었다. 또한 결정된 최적의 수신기 위치의 진위 여부를 통계적으로 검정하는 알고리즘이 제시되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 A
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• pp.414-416
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• 1992

두팔 robot의 dynamic model 에 위치 및 힘의 제어를 적용했을때의 부하분배의 관한 연구가 논문의 주요내용이다. 두팔 robot의 완전한 control을 위해서는 위치 뿐만아니라 힘이 제어를 하여야하며 그럴때의 전제 동력학 식의 타당성 여부를 알기위해서는 안정도 연구를 하여야 한다. 그리고 위치 및 힘의 제어를 했을때의 Load의 distribution 문제에 대하여 언급했다. 이에 관한 연구도 연재 많이 진행되고 있으며 여기서 소개하는 방법은 Load 및 end-effector의 힘의 분포에 주안점을 두어서 해석을 하였다. 이 경우에 Load의 분포에 관한 최적해를 얻기위해서는 두팔에서 소모되는 에너지의 최소치를 찾는 방법과 또 하나는 Load에서 형성되는 힘의 기하학적 구조에 대한 2가지 해석을 하였다. Load의 힘의 분포를 해석하기 위해서는 Load의 동작에 무관하게 적용되는 internal force를 가정하였다.

• Journal of Positioning, Navigation, and Timing
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• 제6권1호
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• pp.27-33
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• 2017

GPS provides the positioning solution in most areas of the world. However, the position error largely occurs in the urban area due to signal attenuation, signal blockage, and multipath. Although many studies have been carried out to solve this problem, a definite solution has not yet been proposed. Therefore, research is being conducted to solve the vehicle localization problem in the urban environment by converging sensors such as cameras and Light Detection and Ranging (LIDAR). In this paper, the precise vehicle localization using 3D LIDAR (Velodyne HDL-32E) is performed in the urban area. As there are many tall buildings in the urban area and the outer walls of urban buildings consist of planes generally perpendicular to the earth's surface, the outer wall of the building meets at a vertical corner and this vertical corner can be accurately extracted using 3D LIDAR. In this paper, we describe the vertical corner extraction method using 3D LIDAR and perform the precise localization by combining the extracted corner position and GPS/DR information. The driving test was carried out in an about 4.5 km-long section near Teheran-ro, Gangnam. The lateral and longitudinal RMS position errors were 0.146 m and 0.286 m, respectively and showed very accurate localization performance.

• 한국멀티미디어학회논문지
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• 제23권2호
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• pp.282-292
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• 2020

In order to minimize casualties from marine vessel accidents that occur frequently at home and abroad, it is important to ensure the safety of the passengers aboard the vessel in the event of an accident. There is an EPIRB system as a system for disaster preparedness in the marine situation currently on the market, but there is a problem that the price is very expensive. In order to overcome the cost problem, which is a disadvantage of previous system, LoRaWAN-based communication is used. LoRaWAN communication-based vessel positioning and risk detection system based on LoRaWAN communication transmits measurement data of each module using two Beacon and GPS modules to stably perform position measurement for both indoor and outdoor situations. The rider danger situation detection system can detect the safety status of the rider using the 3-axis acceleration sensor, collect data from the rider positioning system and the rider safety status detection system, and send to server using LoRa communication. When conducting communication experiments in the long-distance maritime situation and actual communication experiments using the implemented system, it was found that the two experiments showed over 90% communication success rate on average.

• 전기학회논문지
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• 제64권3호
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• pp.445-450
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• 2015

In the moving target problem, the velocity information of the moving target is very important as well as the high accuracy position information. To solve this problem, active researches are being conducted recently with combine the Time Difference of Arrival (TDOA) and Frequency Delay of Arrival(FDOA) measurements. However, since the FDOA measurement is utilizing the Doppler effect due to the relative velocity between the target source and the receiver sensor, it may be difficult to use the FDOA measurement if the moving target speed is not sufficiently fast. In this paper, we propose a method for estimating the position and the velocities of the target by using only the TDOA measurements for the low speed moving target in the indoor environment with sensor network. First, the target position and heading angle are obtained from the estimated positions of two attached transmitters on the target. Then, the target angular and linear velocities are also estimated. In addtion, we apply the Instrumental Variable (IV) technique to compensate the estimation error of the estimated target velocity. In simulation, the performance of the proposed algorithm is verified.

• 전자공학회논문지B
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• 제32B권11호
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• pp.1393-1404
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• 1995

For the factory automation(FA) of production or assembly lines, computer vision techniques have been widely used for the recognition and position-control of objects. In this application, it is very important to analyze characteristic features of each object and to find an efficient matching algorithm using the selected features. If the object has regular or homogeneous patterns, the problem is relatively simple. However, If the object is shifted or rotated, and if the depth of the input visual system is not fixed, the problem becomes very complicated. Also, in order to understand and recognize objects with concentric noise patterns, it is more effective to use feature-information represented in polar coordinates than in cartesian coordinates. In this paper, an algorithm for the recognition of objects with concentric circular noise-patterns is proposed. And position-conrtol information is calculated with the matching result. First, a filtering algorithm for eliminating concentric noise patterns is proposed to obtain concentric-feature patterns. Then a shift, rotation and scale invariant alogrithm is proposed for the recognition and position-control of objects uusing invariant feature information. Experimental results indicate the effectiveness of the proposed alogrithm.

• Industrial Engineering and Management Systems
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• 제3권1호
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• pp.78-84
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• 2004

To optimize movement of a multi-joint robot arm is known to be a difficult problem, because it is a kind of redundant system. Although the end-effector is set its position by each angle of the joints, the angle of each joint cannot be uniquely determined by the position of the end-effector. There exist the infinite number of different sets of joint angles which represent the same position of the end-effector. This paper describes how to manage the angle of each joint to move its end-effector preferably on an X-Y plane with obstacles in the end-effector’s reachable area, and how to optimize the movement of a multi-joint robot arm, evading obstacles. The definition of “preferable” movement depends upon a purpose of robot operation. First, we divide viewpoints of preference into two, 1) the standpoint of the end-effector, and 2) the standpoint of joints. Then, we define multiple objective functions, and formulate it into a multi-objective programming problem. Finally, we solve it using multi-purpose genetic algorithm, and obtain reasonable results. The method described here is possible to add appropriate objective function if necessary for the purpose.