• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.2
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• pp.230-238
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• 2022

Internet of Things(IoT) is a communication technology that collects information of object remotely and controls the function of object by adding a communication function to object that does not have a communication function. For the IoT, various communication technologies such as Wi-Fi, 3GPP, and Bluetooth are available, and Long Range(LoRa) is communication technologies specialized in the IoT concept. LoRa is a communication technology that support long-distance, low-power, and low-speed communication, and is suitable for collecting information generated form object in remote equipment and controlling equipment. Because of these characteristics, it is used in many application field, and various performance improvement studies are in progress. This paper intends to propose an ultra-long-range LoRa communication module that can be used in a wider range of applications. We design and implement hardware, firmware, and application software for testing to develop ultra-long-range LoRa communication modules. The implemented module will be tested in a real environment to verify its performance and to check its utilization.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.6
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• pp.777-788
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• 2014

This paper presents a wide output range, high power efficiency reconfigurable charge pump for driving touch panels with the high resistances. The charge pump is composed of 4-stages and its configuration automatically changes based on the required output voltage level. In order to keep the power efficiency over the wide output voltage range, internal blocks are automatically activated or deactivated by the clock driver in the reconfigurable charge pump minimizing the switching power loss due to the On and Off operations of MOSFET. In addition, the leakage current paths in each mode are blocked to compensate for the variation of power efficiency with respect to the wide output voltage range. This chip is fabricated using $0.18{\mu}m$ BCD process with high power MOSFET options, and the die area is $1870{\mu}m{\times}1430{\mu}m$. The power consumption of the charge pump itself is 79.13 mW when the output power is 415.45 mW at the high voltage mode, while it is 20.097 mW when the output power is 89.903 mW at the low voltage mode. The measured maximum power efficiency is 84.01 %, when the output voltage is from 7.43 V to 12.23 V.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.7 no.2
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• pp.100-105
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• 2014

This paper comparatively analyze to integration case to have a influence detection range estimation about radar cross section in radar system. This paper estimate detection range used to probability of detection in radar equation that used to swerling case 1 in case of radar cross section is small and used to swerling case 3 in case of radar cross section is large. Through simulation, coherent integration and non-coherent integration about swerling case difference were comparatively analyzed. Through simulation, non-coherent integration case is outstanding detection range and we known that coherent integration don't suitable for detection range estimation.

• The Journal of the Acoustical Society of Korea
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• v.40 no.5
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• pp.428-438
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• 2021

For long-range communication in deep water, low carrier frequency is efficient due to a decrease in transmission loss. However, there is a limitation in that the data rate decreases due to a narrow bandwith. In order to increase the data rate in an environment with a limited bandwidth, it is necessary to design a higher-order modulation scheme. This paper analyzes the long-range communication data modulated by higher-order modulation schemes. The long-range communication experiment (23 km ~) was conducted in East Sea in October 2020. During the experiment, a vertical line array was utilized and communication sequences were modulated by Phase Shift Keying (PSK) and Quadrature Amplitude Modulation (QAM) schemes and transmitted by a towed source. In more detail, PSK modulation consists of quadrature PSK and 8PSK, QAM modulation consists of 8QAM and 16QAM. Time reversal processing is applied to mitigate inter-symbol interference by utilizing the correlation between received signals and channel impulse responses. All modulation schemes show successful results at 23 km range, demonstrating the feasibility of higher-order modulation in long-range communication.

• Journal of Power Electronics
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• v.15 no.4
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• pp.861-875
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• 2015

This paper presents a wide frequency range LLC resonant controller IC for LED backlight units. In this paper a new phase-domain resonance deviation prevention circuit (RDPC), which covers a wide frequency and input voltage range, is proposed. In addition, a wide range gate clock generator and an automatic dead time generator are proposed. The chip is fabricated using 0.35 μm BCD technology. The die size is 2 x 2 mm2. The frequency of the clock generator ranges from 38 kHz to 400 kHz, and the dead time ranges from 300 ns to 2 μs. The current consumption of the LLC resonant controller IC is 4 mA for a 100 kHz operation frequency using a supply voltage of 15 V.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.5
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• pp.640-648
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• 2018

Time division wireless communication in tactical MANET is attractive to deliver both high data rates and long-range coverage, and to provide scheduled QoS to mission participants. This paper is about the time synchronization issue of multi-mission USV in tactical MANET. As USV communication coverage becomes longer, the synchronization error also becomes higher; therefore, which results in link disconnection, and consequent failures of reconnection because base station cannot configure necessary parameters over long-distant terminal. We propose a range adaptive time synchronization method to compensate for synchronization errors. The issue of long-range time synchronization problem was identified during maritime communication tests, and we verified the proposed method through analyses of both indoor and outdoor test results.

• Ocean Systems Engineering
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• v.8 no.1
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• pp.33-39
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• 2018

The paper presents a numerical underwater channel model developed in MATLAB for estimating the optical link budget between a light emitting diode (LED) based optical transmitter and a photo diode (PD) receiver when operated in the harbor, coastal and deep waters locations in the Bay of Bengal. The water samples are collected at different locations in the Bay of Bengal using a water sampler during an offshore research cruise. The optical attenuation, the main inherent parameter determining the range of the optical communication link is identified for the different waters using an underwater irradiance measurement system in the laboratory. The identified parameters are applied to the numerical model and found that a 10 W LED and a photo diode based system can provide the optical budget required for a horizontal underwater communication range of about 0.5, 14 and 35 m in the harbor, coastal and deep waters locations respectively. By increasing the transmitter power to 50 W, the operating range of the communication link could be increased up to 53 m in deep water locations in the Bay of Bengal.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.267-270
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• 2000

The feasibility of small linear antenna for near range wireless communications was studied. The requirement of the system are frequency range 9∼12 MHz and antenna size 15 cm. The communication range is about 15 m. The antenna input impedance is very small radiation resistance and very large capacitive reactance. The lossless impedance matching is nearly impossible, therefore lossy matching is considered. The antenna has very low radiation efficiency. The near field calculation has a large uncertainty, but the results can be used as the guideline of a small linear antenna system for a near range wireless communication.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.3 no.1
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• pp.19-23
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• 2010

This study is to develop power line communication and short-range wireless communication system using LED. I will create optical receiver and transmitter using LED and optical sensor and connectors for display device and communication in receiver and transmitter were created. Experiment method is to signal and waveform through oscilloscope date from optical sensor after chosen a highly efficient LED. In addition, reception and transmitter of smoothly data using visible light communication program were checked. I will compliment problems through this experiment and constantly study, improve on power loss.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.151-152
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• 2018

Dedicated Short-Range Communication은 단거리 무선 고속 패킷 통신 기능을 제공하며, 신뢰성, 안전한 데이터 전송 및 낮은 대기 시간으로 인해 Road Safety Application에서 널리 사용되고 있다. 본 논문에서는 SDN의 분산 컨트롤러를 이용하여 DSRC 통신을 제어하는 방식을 제안하였다. 제안한 기법을 실용화한다면 차량을 기반으로 한 실시간 교통 정보 수집이 보다 효과적으로 이루어질 것으로 기대된다.