• International Journal of Advanced Culture Technology
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• v.5 no.1
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• pp.64-69
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• 2017

The rapid growth of algae occurs can induce the algae bloom when nutrients are supplied from anthropogenic sources such as fertilizer, animal waste or sewage in runoff the water currents or upwelling naturally. The algae blooms creates the human health problem in the environment as well as in the water resource managers including hypoxic dead zones and harmful toxins and pose challenges to water treatment systems. The algal blooms in the source water in water treatment systems affects the drinking water taste & odor while clogging or damaging filtration systems and putting a strain on the systems designed to remove algal toxins from the source water. This paper propose the emerging In-Situ self-diagnosable smart algae sensing device with wireless connectivity for smart remote monitoring and control. In this research, we developed the In-Site Algae diagnosable sensing device with wireless sensor network (WSN) connectivity with Optical Biological Sensor and environmental sensor to monitor the water treatment systems. The proposed system emulated in real-time on the water treatment plant and functional evaluation parameters are presented as part of the conceptual proof to the proposed research.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.82-85
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• 1998

Because ATM was originally designed for the optical fiber environment with bit error rate(BER) of 10-11, it is difficult to maintain ATM cell extraction capability in wireless environment where BER ranges from 10-6 to 10-3. Therefore, it must be proposed the algorithm of ATM cell extraction in wereless environment. In this paper, the frame structure and synchronization algorithm satisfyling the above condition are explained, and the new ASIC implementation method of this algorithm is proposed. The known method using shift register needs so many gates that it is not suitable for ASIC implementation. But in the proposed method, a considerable reduction in gate count can be achieved by using random access memory.

• Journal of Sensor Science and Technology
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• v.23 no.3
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• pp.158-164
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• 2014

In indoor sensor networks equalization algorithms based on the minimization of Euclidean distance (MED) for the distributions of constant modulus error (CME) have yielded superior performance in compensating for signal distortions induced from optical fiber links, wireless-links and for impulsive noise problems. One main drawback of MED-CME algorithms is a heavy computational burden hindering its implementation. In this paper, a recursive gradient estimation for weight updates of the MED-CME algorithm is proposed for reducing the operations $O(N^2)$ of the conventional MED-CME to O(N) at each iteration time for N data-block size. From the simulation results of the proposed recursive method producing exactly the same results as the conventional method, the proposed estimation method can be considered to be a reliable candidate for implementation of efficient receivers in indoor sensor networks.

• The Journal of Korea Robotics Society
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• v.10 no.4
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• pp.213-222
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• 2015

This paper presents a column-climbing robot with a mechanical manipulator, which can spirally go up and down a column using wheels. The developed robot can do useful works using the manipulator at the top of a column, e.g., electric pole while communicating wirelessly with an operator panel. It is driven using a battery without any power cables, and the average duration of power is at least one hour. The robot has a function to detect a work object using an optical sensor installed at the bottom of the manipulator. The spirally column-climbing robot developed is demonstrated by experimental works and also by showing it at an exhibition.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.275-281
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• 2005

In this paper, a new algorithm is proposed for high speed roaming in an Intelligent Train Control System(ITCS) and study on optimized positioning of radio communication equipment. A DCS(Data Communication System) which is a main part of CBTC(Communication Based Train Control) system, is consisted of radio based wireless communication system and wired optical system. In the radio based wireless communication, the position of AP enclosures and antennas shall be optimized for the guaranteed communication channel between wayside and trains both in open aired and tunnelled area. Also a communication channel established between wayside and train shall be maintained while train moves at its maximum speed. This study shows the way of determining the optimal position for the railway side communication equipment in Bundang Line and how to achieve continuous communicating channel for tracking and controlling train.

• Electronics and Telecommunications Trends
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• v.33 no.6
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• pp.118-128
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• 2018

With the massive increase in bandwidth for wireless communications, free space optical (FSO) communication has attracted significant interest owing to its outstanding strengths over conventional radio frequency wireless communication such as a wide bandwidth, unlicensed spectrum, low power consumption, small size, electromagnetic interference immunity, long-range propagation, and improved security. In recent years, FSO technology has been studied intensively for use in terrestrial and underwater autonomous and unmanned mobile systems, a rapidly growing application area, including robots, drones, unmanned aerial vehicles, autonomous vehicles, unmanned trains, and unmanned submarines. In this report, we review the recent trends and key technologies for the mobile FSO system, and introduce our drone-based mobile FSO system, which is currently under development.

• Journal of Advanced Information Technology and Convergence
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• v.8 no.2
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• pp.147-157
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• 2018

In this study, we analyzed an outdoor visible light communication system and implemented it through a simulation. We designed a Reed-Solomon encoder, a variable interleaver structure, and set it to the Institute of Electrical and Electronics Engineers (IEEE) 802.15.7 PHY I specification mode. We also analyzed the performance of an additive white gaussian noise (AWGN) channel environment using a root-raised-cosine (RRC) filter, implemented a MATLAB simulation and analyzed its performance. The results showed a requirement for an additional signal-to-noise ratio (SNR) of approximately 1.5 dB in a 3-ray multipath visible light channel environment than in an AWGN environment.

• Korean Journal of Optics and Photonics
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• v.16 no.5
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• pp.417-422
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• 2005

When an optical pulse propagates through the atmospheric channel, it is attenuated and spreaded by the atmospheric turbulence. This pulse broadening produces the intersymbol interference(ISI) between adjacent pulses. Therefore, adjacent pulses are overlapped, and the bit rates and the repeaterless transmission length are limited by the ISI. In this paper, the ISI as a function of the refractive index structure constant that presents the strength of atmospheric turbulence is found using the temporal momentum function, and is numerically analyzed fer the basic SONET transmission rates. The numerical results show that ISI is gradually increasing at the lower transmission rate than the OC-192(9.953 Gb/s) system and is slowly converging after rapid increasing at the higher transmission rate than the OC-768(39.813 Gb/s) system as the turbulence is stronger. Also, we know that accurate information transmission is possible to 10[km] at the OC-48(2.488 Gb/s) system under any atmospheric turbulence, but is impossible under the stronger turbulence than $10^{-14}[m^{-2/3}]$ at the 100 Gb/s system, $10^{-13}[m^{-2/3}]$ at the OC-768 system, and $10^{-12}[m^{-2/3}]$ at the OC-192 system, because the ISI is seriously induced.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.2
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• pp.81-86
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• 2013

In this paper, the parameter identification for localization scheme for the optics-based micro sensor node is conducted. We analyzed short measurement range problem which can be occurred in optical based micro sensor node localization method using a time of flight. And we set up the theory for distance and maximum reflected laser power to overcome the problem by identifying hardware parameters like laser power, effective area of MEMS CCR, sensitivity of photodetector, and so on. Experimental results of measurement of maximum reflected laser power were compared with results of the theory. By using the theory, we can identify hardware parameters of localization scheme to measure particular position of the optics-based micro sensor node.

• Journal of Ocean Engineering and Technology
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• v.32 no.2
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• pp.143-150
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• 2018

In this study, we designed and developed an underwater LED communication system composed of an LED and a photo sensor. In addition, we experimented with video data transmission in a water tank. Two communication modules were installed in the 3 m water tank, and the image data transmission test was successfully performed at a rate of 20 frames per second(FPS), image resolution of $480{\times}272$, and data communication speed of 4 Mbps.