• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 춘계학술대회
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• pp.241-243
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• 2015

최근 인터넷을 기반으로 사물을 연결하여 사람과 사물 간의 정보 소통을 가능하게 하는 지능형 서비스로서 사물 인터넷 서비스(IoT)에 대한 관심이 증가하고 있다. 특히 스마트 기기의 발전과 더불어 실내 위치 기반 서비스에 대한 수요는 급격히 증가하고 있다. 실내 위치 정보 측정을 위해 BLE(Bluetooth Low Energy) 기술의 iBeacon이 제공하는 기본적인 신호만을 이용하면 신호 간섭 등의 다양한 이유로 신뢰할 수 없는 신호 데이터로 인해 실내 위치 정보의 신뢰도는 현격히 낮아지게 된다. 본 논문에서는 iBeacon의 신호 정보로 부터 신뢰성 있는 위치 정보를 얻기 위해 유전 연산을 통해 효과적이고 신뢰도 높은 위치 정보를 얻는 기법을 제안한다.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2004년도 한국우주과학회보 제13권2호
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• pp.296-299
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• 2004

KARI precision attitude determination system has been developed for high accurate geo-coding of KOMPSAT-2 image. Sensor data from two star trackers and a IRU are used as measurement and dynamic data. Sensor data from star tracker are composed of QUEST and unit vector filter. Filter algorithms consists of extended Kalman filter, unscented Kalman filter, and least square batch filter. The type of sensor data and filter algorithm can be chosen by user options. Estimated parameters are Euler angle from 12000 frame to optical bench frame, gyro drift rate bias, gyro scale factor, misalignment angle of star tracker coordinate frame with respect to optical bench frame, and misalignment angle of gyro coordinate frame with respect to optical bench frame. In particular, ground control point data can be applied for estimating misalignment angle of star tracker coordinate frame. Through the simulation, KPADS is able to satisfy the KOMPSAT-2 mission requirement in which geo-location accuracy of image is 80 m (CE90) without ground control point.

• Journal of Biosystems Engineering
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• 제14권2호
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• pp.104-114
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• 1989

The most important subject in developing agricultural robots for fruit harvesting is to detect accurately the location of a fruit about the given coordinate system. This study was carried out to develop an image processing algorithm which enables finding out the three dimensional locations of a fruit. The digital image processing device consisted of an optosensor (Closed-circuit TV camera), image processing interface board (Digitizer) and microcomputer (IBM PC/AT). A stereo-image processing method using the two cameras attached to the manipulator was evaluated through experiment with apples. The accuracy and quickness of detecting the location of apples by this method was not satisfactory. The maximum errors of the detected locations by the stereo-image processing method in x-, Y-, and z- directions were 3, 4 and 4 cm, respectively. The maximum time required to get the rectangular coordinate data of a fruit was about 2 minutes.

• Journal of information and communication convergence engineering
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• 제10권4호
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• pp.390-395
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• 2012

This paper describes an implementation of automatic mutual localization of swarm robots using a particle filter. Each robot determines the location of the other robots using wireless sensors. The measured data will be used for determination of the movement method of the robot itself. It also affects the other robots' self-arrangement into formations such as circles and lines. We discuss the problem of a circle formation enclosing a target that moves. This method is the solution for enclosing an invader in a circle formation based on mutual localization of the multi-robot without infrastructure. We use trilateration, which does require knowing the value of the coordinates of the reference points. Therefore, specifying the enclosure point based on the number of robots and their relative positions in the coordinate system. A particle filter is used to improve the accuracy of the robot's location. The particle filter is operates better for mutual location of robots than any other estimation algorithms. Through the experiments, we show that the proposed scheme is stable and works well in real environments.

• 산업경영시스템학회지
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• 제30권3호
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• pp.44-53
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• 2007

Forming central warehouses for a number of stores can save costs in the continuous review inventory model due to economy of scale and information sharing. In this paper, transportation costs are included in this inventory model. Hence, the tradeoff between inventory-related costs and transportation costs is required. The main concern of this paper is to determine the number and location of central warehouses. Transportation costs are dependent on the distance from several central warehouses to each store. Hence, we develop an efficient simulated annealing algorithm using distance-based local search heuristic and merging heuristic to determine the location and the number of central warehouses. The objective of this paper is to minimize total costs such as holding, setup, penalty, and transportation costs. The performance of the proposed approach is tested by using some computational experiments.

• 산업공학
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• 제19권1호
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• pp.78-85
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• 2006

A centralized inventory system provides a number of stores with cost reduction, information sharing. In this paper, transportation costs are included in the inventory model. To build centralized warehouses, two things should be considered: how many warehouses are required and where these are located. The objective of this paper is to develop efficient heuristics to determine the location and the number of central warehouses by minimizing total costs. Throughout some computational experiments, the results of the heuristics are compared with an optimal solution.

• Journal of Advanced Marine Engineering and Technology
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• 제39권2호
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• pp.187-194
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• 2015

Accurate relative location estimation is a key requirement in indoor localization systems based on wireless sensor networks (WSNs). However, although these systems have applied not only various optimization algorithms but also fusion with sensors to achieve high accuracy in position determination, they are difficult to provide accurate relative azimuth and locations to users because of cumulative errors in inertial sensors with time and the influence of external magnetic fields. This paper based on ultra-wideband positioning system, which is relatively suitable for indoor localization compared to other wireless communications, presents an indoor localization system for estimating relative azimuth and location of location-unaware nodes, referred to as target nodes without applying any algorithms with complex variable and constraints to achieve high accuracy. In the proposed method, the target nodes comprising three mobile nodes estimate the relative distance and azimuth from two reference nodes that can be installed by users. In addition, in the process of estimating the relative localization information acquired from the reference nodes, positioning errors are minimized through a novel modified rounding estimation technique in which Kalman filter is applied without any time consumption algorithms. Experimental results show the feasibility and validity of the proposed system.

• 산업경영시스템학회지
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• 제32권2호
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• pp.57-65
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• 2009

In continuous review inventory model, (${\varrho}$, ${\gamma}$) system, order quantity(${\varrho}$) and reorder point(${\gamma}$) should be determined to calculate inventory-related cost that consists of setup, holding, and penalty costs. The procedure to obtain the exact value of ${\varrho}$ and ${\gamma}$ is complex. In this paper, a regression analysis is proposed to get the approximate inventory-related cost without the determination of ${\varrho}$ and ${\gamma}$ in the case that the standard deviation(${\sigma}$) of the lead time demand is small or that the mean(${\mu}$) of the lead time demand is proportional to ${\sigma}$. To save inventory-related cost, central warehouses with (${\varrho}$, ${\gamma}$) system can be built. Central warehouse can provide some stores with products with the consideration of the tradeoff between inventory-related cost and transportation cost. The number and the location of central warehouses to cover all the stores are determined by a regression-based approach. The performance of the proposed approach is tested by using some computational experiments.

• 한국항공우주학회지
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• 제33권11호
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• pp.41-47
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• 2005

현재 240여기의 상업용 정지궤도 통신위성이 운용 중에 있지만, GPS 등의 위치항법 위성의 고도보다 높을 뿐만 아니라 나쁜 가시성으로 인하여 중궤도 위치항법시스템을 사용할 수 없으므로 반드시 지상관제소에 의해 추적되어야 한다. 또한 지상관제소에서 관측할 경우 정지궤도 위성은 거의 움직이지 않는 것처럼 보이기 때문에 수 미터급의 정지궤도위성의 위치결정 정밀도를 높이기 위해서 충분히 멀리 떨어진 2곳 이상의 추적안테나를 사용하여야 한다. 따라서 본 논문에서는 정지궤도 위성의 궤도결정과 자동운용을 위해서 정지궤도 고도보다 높은 2일 주기의 원형궤도를 사용하는 GSPS(Geostationary Satellite Positioning System)을 제안하였다. GSPS는 지상추적소에서 정밀하게 위치가 결정된 자기 자신의 위치정보 및 시각정보, 보정데이터와 정지궤도 위성의 운용을 위한 명령을 GSPS 위성에 전송하여 정지궤도위성에 위치정보를 제공하는 기능을 한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.184-186
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• 1999

This paper presents a method for security constrained optimal reactive power planning in electric power systems. This method deals with corrective mode optimal reactive power dispatch in each (n-1)contingency system state and determination of the location and amount of reactive sources in preventive mode. In this paper the proposed scheme uses Benders decomposition method to determine the proper amount and location of reactive support in order to maintain a proper voltage profile and minimize active power transmission losses. This method is tested on IEEE 30 bus test system to prove effectiveness.