• Journal of the Optical Society of Korea
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• v.16 no.4
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• pp.331-335
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• 2012

A miniaturized laser beam transmitter, in which a visible laser module at ${\lambda}$=650 nm is precisely stacked upon an infrared (IR) module at ${\lambda}$=905 nm, has been proposed and constructed to provide an IR collimated beam in conjunction with a collinear monitoring visible beam. In particular, the IR beam is selectively dispersed through a perforated sheet diffuser, so as to create a rapidly diverging close-range beam in addition to a highly defined long-range beam simultaneously. The complementary close-range beam plays a role in mitigating the blind region in the vicinity of the transmitter, which is inevitably missed by the main long-range beam, thereby uniformly extending the transmitter's effective trajectory that is sensed by a receiver. The proposed transmitter was designed through numerical simulations and then fabricated by incorporating a diffuser sheet, perforated with an aperture of 2 mm. For the manufactured transmitter, the IR long-range beam was observed to have divergences of ~2.3 and 1.6 mrad in the fast and slow axes, respectively, while the short-range beam yielded a divergence of ~24 mrad. The angular alignment between the long-range IR and visible beams was as accurate as ~0.5 mrad. According to an outdoor feasibility test involving a receiver, the combination of the IR long- and short-range beams was proven to achieve a nearly uniform trajectory over a distance ranging up to ~600 m, with an average detectable cross-section of ${\sim}60{\times}80cm^2$.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.4
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• pp.715-722
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• 2019

This paper introduces the implementation of an user-aware system using a visible light communication and its operations. The user-aware system using a visible light communication consists of the transmitter based on the Android system and the receiver based on an open-source controller. In the transmitter, user's personal information data is encoded and converted to visible light signals by the Android camera interface. In the receiver, the photodiode module receives the incoming visible light signals and converts to electrical signals and the open-source controller, that is arduino processes the received data. The processing module finds the start bit of 0111 to determine the user information data from the packet for the burst-mode communication. According to the experimental results, the proposed system successfully transmits and receives visible light data with the manchester encoding.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.11
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• pp.1428-1433
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• 2019

Interest in mountain accidents among the technical trends of disasters in Korea is increasing continuously. When accidents occur, the most common methods are location tracking and accident reporting using smartphones, and rescue activities are being carried out by using them. In this paper, we proposed an improvement of wireless safety system for mountain climbing safety using 447 FSK. Using the 447 MHz band transmitter / receiver, it accumulates position coordinates and data through position transmission and rescue signal transmission in case of anomalies. If a sender is out of the threshold of the set area range, a danger warning notification can be generated to quickly exit the danger zone. Provide services. In addition, it is considered that the health condition of the sender is continuously checked and the receiver is warned when the specified threshold is exceeded, so that it is possible to respond to the sender's disaster.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.55-57
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• 2022

In this study, a customized semi-passive RFID receiver module was implemented for in-VIVO deep tissue photo-therapy. A novel wireless technique is required due to a limitation of RF communication in body environment, as internal body has a complex structure such as, skin, fat, skeleton, water, and so on. Recently, coherently incoherent beamforming (CIB) based on RFID was introduced and it is able to transmit wireless signal with high reliability under the incoherent condition such as in-VIVO deep tissue. The proposed miniature photo capsule based on RFID consists of miniature controller, ultra small LED array and wireless RFID chip. RF Reader can access with standard RFID protocol (ISO 18000-6c) using UHF RFID antenna, a control command is wirelessly writtern on USER Bank memory. With received control command, therapy LED array dims with mulilevel under timer control. The signal process of designed RFID photo therapy capsule is analyzed and evaluated under the various environments in detailed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.2 s.105
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• pp.171-177
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• 2006

A low-cost, high-performance 40 Gb/s clock recovery module using a phase-locked loop(PLL) for a 40 Gb/s optical receiver with the clock-hold function has been designed and implemented. It consists of a clock extractor circuit, an RF mixer and a frequency discriminator for phase/frequency detection, a VC-DRO, a phase shifter, and a clock-hold circuit. The extracted 40 GHz clock is synchronized with a stable 10 GHz VC-DRO. The clock stability and jitter characteristics of the implemented PLL-based clock recovery module are significantly improved as compared with those of the conventional open-loop type clock recovery module with a DR filter. The measured peak-to-peak RMS jitter is about 230 fs. When an input signal is dropped, the 40 GHz clock is maintained continuously by the hold circuit.

• Journal of Advanced Navigation Technology
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• v.8 no.1
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• pp.19-26
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• 2004

This paper deals with the automatic flight control system for an unmanned target drone which is operated by an army as an anti-air gun shooting training. By automation of unmanned target drone that is manually operated by external pilot, pilot can reduce workload and an army can reduce the budget. Most UAVs which are developed until today use high-cost sensors as AHRS and IMU to measure the attitude, but those are contradictory for the reduction of budget. This paper says the development of low-cost automatic flight control system which makes possible of automatic flight with low-cost sensors. We have developed the integrated automatic flight control system by integrating electricity module, switching module, monitoring module and RC receiver as an one module. We also prove the performance of automatic flight control system by flight test.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.12
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• pp.2417-2424
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• 2016

Small size and light weight is very important for components used in radar mounted platform such as airborne radar. Recently, the active phased array radar is developed as an array of antennas for thousands of transmit/receive modules to be used as a multi-function radar that can detect and track targets. In this case, the size and weight of the transmit/receive modules are critical factor for developing the radar. In this paper, we developed a compact transmit/receive module using the 10W RF MEMS switch domestically localizing and reduced the circuit area to about 86.5% compared to using a circulator. The developed module satisfies not only electrical requirements but also MIL-STD's environmental specifications. So it can be used in a military device. It can be used at adaptive tunable receivers, reconfigurable smart active antennas and wide band beam electrical steering antennas.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.2
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• pp.27-32
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• 2018

In this paper, W-band transceiver module for compact radar has been designed and fabricated. Utilizing proposed microstrip-to-waveguide transition, the error between design and implementation is reduced. The proposed transition provides less than 1 dB insertion loss per transition and reliability for fabrication. In order to apply compact radar with dual-polarized monopulse directly, W-band transmitter with 28 dBm output power is designed and developed. Also, 6 channels of receiver module with low noise figure 13.5 dB and maximum 17 dBm input P1dB is developed. Proposed W-band transceiver module is expected compact radar application for dual-polarized monopulse signal processing system.

• Journal of the Institute of Convergence Signal Processing
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• v.19 no.2
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• pp.54-60
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• 2018

In this paper, we propose an efficient automatic control method for the collision avoidance of drones. In general, the drones are controlled by transmitting to the flight control (FC) module the received PWM signals transmitted from a RC controller which transduce movements of the knob into PWM signal. We implemented the collision avoidance module in-between receiver and FC module to monitor and change the throttle, pitch and roll control signals to avoid drone collision. In order to avoid the collision, a LiDAR distance sensor and a servo-motor are installed and periodically measure the obstacle distance within -45 degrees from 45 degrees in flight direction. If the collision is predicted, the received PWM signal is changed and transmitted to the FC module to prevent the collision. We applied our proposed method to a hexacopter and the experimental results show that the safety is improved because it can prevent the collision caused by the inadvertency or inexperienced maneuver.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.522-525
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• 2015

In this paper, we propose a walking aid system that guides route to visually impaired people in order to recognize uncertain obstacles based on tactile stimulation. The proposed system is composed of the touch-based obstacle detection module, the obstacle height detection module, and the route guidance algorithms. The touch-based obstacle detection module detects each obstacle, which is located at left, right, and front of a visually impaired person by stimulating his thumb with the rotational force of the servomotor. The obstacle height detection module integrates detected data by the linear arrangement of ultrasonic sensors to identify the height of an obstacle about 3 of-phase(i.e., high, medium, low). The proposed route guidance algorithm guides an optimized path to the visually impaired person by updating his current position information based on the signal of the built-in GPS receiver in smartphone. In addition, the route guidance algorithm delivers information with speech to a visually impaired person through Bluetooth commuination in the developed route guidance app. The proposed system can create a path to avoid the obstacles by recognizing the placed situation of the obstacles with exploring the uncertain path.