• 제어로봇시스템학회논문지
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• 제17권10호
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• pp.1051-1058
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• 2011

Unmanned autonomous forklifts have a great potential to enhance the productivity of material handling in various applications because these forklifts can pick up and deliver loads without an operator and any fixed guide. Especially, automation of pallet loading and unloading technique is useful for enhancing performance of logistics and reducing cost for automation system. There are, however, many technical difficulties in developing such forklifts including localization, map building, sensor fusion, control, and so on. This is because the system requires numerous sensors, actuators, and controllers that need to be connected with each other, and the number of connections grows very rapidly as the number of devices grows. This paper presents a vision sensorbased autonomous loading and unloading for network-based unmanned forklift where system components are connected to a shared CAN network. Functions such as image processing and control algorithm are divided into small tasks that are distributed over a number of microcontrollers with a limited computing capacity. And the experimental results show that proposed architecture can be an appropriate choice for autonomous loading in the unmanned forklift.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권9호
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• pp.1632-1652
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• 2011

This paper considers the object tracking problem in three dimensional (3-D) space when the azimuth and elevation of the object are available from the passive acoustic sensor. The particle filtering technique can be directly applied to estimate the 3-D object location, but we propose to decompose the 3-D particle filter into the three planes' particle filters, which are individually designed for the 2-D bearings-only tracking problems. 2-D bearing information is derived from the azimuth and elevation of the object to be used for the 2-D particle filter. Two estimates of three planes' particle filters are selected based on the characterization of the acoustic sensor operation in a noisy environment. The Cramer-Rao Lower Bound of the proposed 2-D particle filter-based algorithm is derived and compared against the algorithm that is based on the direct 3-D particle filter.

• Journal of information and communication convergence engineering
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• 제12권4호
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• pp.215-220
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• 2014

We consider quantization optimized for distributed estimation, where a set of sensors at different sites collect measurements on the parameter of interest, quantize them, and transmit the quantized data to a fusion node, which then estimates the parameter. Here, we propose an iterative quantizer design algorithm with a weighted distance rule that allows us to reduce a system-wide metric such as the estimation error by constructing quantization partitions with their optimal weights. We show that the search for the weights, the most expensive computational step in the algorithm, can be conducted in a sequential manner without deviating from convergence, leading to a significant reduction in design complexity. Our experments demonstrate that the proposed algorithm achieves improved performance over traditional quantizer designs. The benefit of the proposed technique is further illustrated by the experiments providing similar estimation performance with much lower complexity as compared to the recently published novel algorithms.

• Journal of information and communication convergence engineering
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• 제16권3호
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• pp.142-147
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• 2018

We present a practical design algorithm for quantizers at nodes in distributed systems in which each local measurement is quantized without communication between nodes and transmitted to a fusion node that conducts estimation of the parameter of interest. The benefits of vector quantization (VQ) motivate us to incorporate the VQ strategy into our design and we propose a low-complexity design technique that seeks to assign vector codewords into sets such that each codeword in the sets should be closest to its associated local codeword. In doing so, we introduce new distance metrics to measure the distance between vector codewords and local ones and construct the sets of vector codewords at each node to minimize the average distance, resulting in an efficient and independent encoding of the vector codewords. Through extensive experiments, we show that the proposed algorithm can maintain comparable performance with a substantially reduced design complexity.

• 제어로봇시스템학회논문지
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• 제5권6호
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• pp.764-776
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• 1999

In this paper, a tracking algorithm for a maneuvering single target in the presence of multiple data from multiple sensors is investigated. Allowing individual sensors to function by themselves, the estimates from individual sensors on the same target are fused for the purpose of improving the state estimate. The filtering method adopted in the local sensors is the variable dimensional filter with input estimatio technique, which consists of a constant velocity model and a constant acceleration model. A posteriori probability for the maneuvering hypothesis is newly derived. It is shown that the relation function of the a posteriori probability is a function of only the covariance of the fused estimates. Simulation results are provided.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.18-21
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• 2008

Lee (2008) proposed the pansharpening method to reconstruct at the higher resolution the multispectral images which agree with the spectral values observed from the sensor of the lower resolution values. It outperformed over several current techniques for the statistical analysis with quantitative measures, and generated the imagery of good quality for visual interpretation. However, if a small object stretches over two adjacent pixels with different spectral characteristics at the lower resolution, the pixels of the object at the higher resolution may have different multispectral values according to their location even though they have a same intensity in the panchromatic image of higher resolution. To correct this problem, this study employed an iterative technique similar to the image restoration scheme of Point-Jacobian iterative MAP estimation. The effect of pansharpening on image segmentation/classification was assessed for various techniques. The method was applied to the IKONOS image acquired over the area around Anyang City of Korea.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1996년도 특별강연 및 추계학술발표 개요집
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• pp.142-144
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• 1996

This paper discusses the application of infra-red thermography in monitoring the robotic arc welding process, and it's potential for weld bead dimension and seam tracking control. Thermal images illustrating weld pool formation dynamics and heat distribution phenomena are digitized and their characteristics are measured. At each sampling point the maximum depth of penetration is recorded together with additional information regarding weld bead placement in relation to the seam location. Deficiencies such as incomplete penetration and lack of side wall fusion are readily identified and can be remained during the process. The technique can help an increase in productivity and weld quality by minimizing the amount of post process rework and inspection efforts needed otherwise.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2019년도 추계학술대회
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• pp.73-75
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• 2019

폐배터리를 조합하여 배터리 팩을 구성 시, 사용환경이 상이한 폐배터리 간의 전압/SOC의 편차가 존재하여 장기간 사용시 과충전/과방전과 같은 안전상을 문제가 발생할 가능성이 크다. 따라서 본 논문에서는 확장 칼만 필터를 기반 센서 융합 방법을 사용하여 폐배터리 팩의 셀 간 SOC 불균형을 추정하는 알고리즘을 제안한다. 검증은 셀간 전압 불균형이 있는 노화된 배터리 팩에 임의의 전류 프로파일을 인가하여 제안된 알고리즘을 검증한다.

• 전기전자학회논문지
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• 제23권2호
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• pp.710-715
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• 2019

We consider parameter estimation in distributed systems in which measurements at local nodes are quantized in a non-regular manner, where multiple codewords are mapped into a single local measurement. For the system with non-regular quantization, to ensure a perfect independent encoding at local nodes, a local measurement can be encoded into a set of a great number of codewords which are transmitted to a fusion node where estimation is conducted with enormous computational cost due to the large cardinality of the sets. In this paper, we propose an efficient estimation technique that can handle the non-regular quantized data by efficiently finding the feasible combination of codewords without searching all of the possible combinations. We conduct experiments to show that the proposed estimation performs well with respect to previous novel techniques with a reasonable complexity.

• 한국해양공학회지
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• 제21권3호
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• pp.46-51
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• 2007

A multi-purpose environmental monitoring system has been developed as a commercially available standard using the technique of hetero-core spliced fiber optic sensors, for the purposes of monitoring large-scale structures and preserving natural environments. The monitoring system has been tested and evaluated in a possible outdoor condition, in view of the full-scale operation at actual sites to be monitored. Additionally, the developed system in this work conveniently provides us with various options of sensor modules intended for monitoring such physical quantities as displacement, distortion, pressure, binary states, and liquid adhesion. Two channels of optical fiber line were monitored in each channel, three displacement sensor modules were connected in series, in order to examine the performance to a pseudo-cracking experiment in the outdoor situation and to clarify temperature influences an the system, in terms of the coupling of optical connectors and the OTDR stability. The results from the pseudo-cracking experiment agreed with the actual cracks, by means of calculation, based an the detected displacement values and their geometrical arrangement of the used sensor modules. The temperature change, ranging from 10 to $20^{\circ}C$ resulting from the 10-days free running operation, was found to influence the system stability of ${\pm}10{\mu}m$, primarily due to the coupling instability of the used optical connectors. It was found that fusion splicing, rather than the use of connectors, reduced the fluctuation dawn to ${\pm}2{\mu}m$. The specification and performance of various option modules have been demonstrated to show the capability of inspecting various physical quantities by use of the single system, which would be suitable for multi-purpose environmental monitoring.