• Journal of the Optical Society of Korea
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• v.5 no.3
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• pp.83-89
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• 2001

Room temperature quasi-continuous operation is achieved near 1556 nm with threshold current as low as 2.2 mA from a 5.6-${\mu}{\textrm}{m}$ oxide-aperture vertical-cavity surface-emitting laser. Wafer fusion techniques are employed to combine the GaAs/AlGaAs mirror and the InP-based InGaAs/InGaAsP active layer. In this structure, an $Al_x/O_y$/GaAs distributed bragg reflector and intra-cavity contacts are used to reduce free carrier absorption.

• Proceedings of the Korean Nuclear Society Conference
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• 2002.05a
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• pp.42.1-42
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• 2002

• Proceedings of the Korean Information Science Society Conference
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• 1999.10b
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• pp.327-332
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• 1999

Fuzzy systems, neural networks and genetic algorithms have different origins and thus have differently developed their own unique characteristics. These characteristics can be used as a good complement to the others. Therefore, many researches have been devoted to not only these techniques but also fusion of them. This paper briefly summarizes these three techniques and surveys the researches on fusion of them.

• Bulletin of the Korean Chemical Society
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• v.28 no.10
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• pp.1811-1814
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• 2007

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.731-734
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• 2011

• Bulletin of the Korean Chemical Society
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• v.34 no.4
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• pp.1286-1289
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• 2013

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.779-780
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• 2011

• Bulletin of the Korean Chemical Society
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• v.25 no.10
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• pp.1571-1574
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• 2004

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.1
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• pp.58-73
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• 2014

As is well known, cooperative sensing can significantly improve the sensing accuracy as compared to local sensing in cognitive radio networks (CRNs). However, a large number of cooperative secondary users (SUs) reporting their local detection results to the fusion center (FC) would cause much overhead, such as sensing delay and energy consumption. In this paper, we propose a fast cooperative sensing scheme, called double threshold fusion (DTF), to reduce the sensing overhead while satisfying a given sensing accuracy requirement. In DTF, FC respectively compares the number of successfully received local decisions and that of failed receptions with two different thresholds to make a final decision in each reporting sub-slot during a sensing process, where cooperative SUs sequentially report their local decisions in a selective fashion to reduce the reporting overhead. By jointly considering sequential detection and selective reporting techniques in DTF, the overhead of cooperative sensing can be significantly reduced. Besides, we study the performance optimization problems with different objectives for DTF and develop three optimum fusion rules accordingly. Simulation results reveal that DTF shows evident performance gains over an existing scheme.

• Journal of Environmental Impact Assessment
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• v.27 no.4
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• pp.378-393
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• 2018

As atmospheric fine dust problems in Korea become more serious, there are growing needs to find the concentration of fine particles in indoor and outdoor areas and there are increasing demands for sensor-based portable monitoring devices capable of measuring fine dust concentrations instantly. The low-cost portable monitoring devices have been widely manufactured and used without the prescribed certification standards which would cause unnecessary confusion to the concerned public. To evaluate the reliability those devices and to improve their usability, following studies were conducted in this work; 1) The comparisons between sensor-based devices and comparison with more accurate devices were performed. 2) Several experiments were conducted to understand usefulness of the portable monitoring devices. As results, the absolute concentration levels need to be adjusted due to insensitivity of the tiny light scattering sensors in the portable devices, but their linearity and reproducibility seem to be acceptable. By using those monitoring devices, users are expected to have benefits of recognizing the changes of concentration more quickly and could help preventing themselves from the adverse health impacts.