• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.12
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• pp.103-108
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• 2004

In this paper, we present MIMIC(Millimeter-wave Monolithic Integrated Circuit) up-mixer with low conversion loss and low LO power for the V-band transmitter applications. The up-mixer was successfully integrated by using 0.1 ㎛ GaAs pseudomorphic HEMTs(PHEMTs) and coplanar waveguide (CPW) structures. The circuit is designed to operate at RF frequencies of 60.4 GHz, IF frequencies of 2.4 GHz, and LO frequencies of 58 GHz. The fabricated MIMIC up-mixer size is 2.3 mmxl.6 mm. The measured results show that the low conversion loss of 1.25 dB when input signal is -10.25 dBm at LO power of 5.4 dBm. The LO to RF isolation is 13.2 dB at 58 GHz. The fabricated V-band up-mixer represents lower LO input power and conversion loss characteristics than previous reported millimeter-wave up-mixers.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.6
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• pp.83-90
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• 2018

LoRa (Long Range) is a long-distance, low-power communication technology. Broader range of communication than NFC technology allows communication without having to install multiple APs and reduces the cost of initial infrastructure deployment. MQTT (Message, Queuing, Telemetry, Transport) protocol is also low power and lightweight protocols. It can increase module persistence and reduce maintenance costs when used with LoRa. In this paper, we developed a system for compiling various environmental information in a factory using LoRa and MQTT. Environmental sensor data from long distances can be monitored by the management system and the facilities in each workshop can be controlled. Performance tests have also shown that the use of LoRa and MQTT is effective in terms of long-distance and power consumption.

• Journal of Satellite, Information and Communications
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• v.9 no.2
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• pp.7-11
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• 2014

In this paper, we designed resistive MMIC mixer using $0.5{\mu}m$ p-HEMT process. This Mixer is designed to have a similar performance in -4 ~ 4 dBm local oscillator signal power level and to maintain a constant conversion loss and linear performance due to the variation of local signal. In order to have such characteristics, we designed new feedback circuit topology by using FET, and minimized performance change for LO signal power level variation, also obtain MMIC mixer characteristics which is able to apply in wideband. In the design result, When the LO signal power is -4 ~ 4 dBm, there was 6 dB conversion loss and it came up with the excellent result that IIP3 got over 30 dBm in 0.5 ~ 2.6GHz frequency band.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.1
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• pp.17-28
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• 2019

6LoWPAN based on IEEE 802.15.4 is a realistic standard platform for various Internet of Things (IoT) applications. To bootstrap the LoWPAN (Low-power Wireless Personal Area Network), each device must perform 6LoWPAN-ND address registration to assign a unique IPv6 address. Without adequate security mechanisms, 6LoWPAN-ND is vulnerable to a variety of security attacks including corrupted node attacks. Several security mechanisms have been proposed as a supplement to the vulnerability, but the vulnerability exists because it relies solely on IEEE 802.15.4 hop-by-hop security. In this paper, we propose and analyze a vulnerability of 6LoWPAN-ND address registration and a new security mechanism suitable for preventing the attack of damaged node. It also shows that the proposed security mechanism is compatible with the Internet Engineering Task Force (IETF) standard and is more efficient than the mechanism proposed in the IETF 6 lo WG.

• Journal of the Korean GEO-environmental Society
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• v.1 no.1
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• pp.35-42
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• 2000

The settlement characteristics of waste landfill site must be considered in the design of sanitary landfill as well as in the course of the rehabilitation of the landfill site. Among prediction methods for settlement of landfill site, especially Gibson and Lo model and Power Creep Law have been successfully applied to the landfill site where the amount of settlement was large and the secondary settlement was obvious. Therefore, the effects of organic content on the model parameter values utilized in both Gibson Lo model and Power Creep Law were studied by using a large consolidation testing apparatus. The organic content is each 20%, 40%, 60% of total volume and consolidation load is $0.1{\sim}1.6kg/cm^2$. The main results can be summarized as follows: (1) The reference compressibility of Power Creep Law is decreased according to the increments of consolidation load: (2) The field measurement is more similar to the Power Creep Law than the Gibson and Lo model.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.11
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• pp.65-71
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• 2010

This paper presents a 14-band LO generator architecture for MB-OFDM UWB systems using 3.1 GHz~10.6 GHz frequency band. The proposed LO generator architecture has been consisted of only one PLL and the fewest nonlinear components to generate 14 LO signals with high purity while consuming low dc power consumption. In addition, major spurious generated from the LO generator have been located in the out of UWB band. The proposed LO generator has been implemented in a $0.13-{\mu}m$ CMOS technology and consumes a dc power consumption of 93~103 mW from a 1.5 V supply. The simulation results show an in-band spurious suppression ratio of more than 41 dBc and a band-switching time of below 3 nsec.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.139-141
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• 2019

This paper proposes the application of LoRa network, which has been under various research recently, to use control system for the transfer of Unmanned Vehicle. LoRa( Long Range) has a wide coverage of up to30 km, and is characterized by large-scale low-power long-distance radio communication. LoRa has already been studied in various industries. It is also proposed to study various functions by utilizing LoRa network and applying it to the control system of the uninhabited entity.

• Journal of Navigation and Port Research
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• v.27 no.4
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• pp.443-447
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• 2003

In this work. using 0.2 GaAs modulation doped FET(MODFET), a high performance DBS downconverter MMIC was developed for direct broadcasting satellite (DBS) application. Without LNA, the downconverter MMIC showed a very low noise of 4.8 dB, which is lower by 3 dB than conventional ones. A low LO power of -10 dBm was required for the normal DBS operation of the downconverter MMIC. which reduced the power consumption via a removal of LO amplifier on MMIC. It required only a low power consumption of 175 mW, which is lower than 70 percent of conventional ones. The LO leakage power at IF output was suppressed to a lower level than 30 dBm, which removes a bulky LO rejection filter on a board. The fabricated chip, which include a mixer, If amplifiers. LO rejection filter, and active balun, exhibited a small size of $0.84{\times}0.9\textrm{mm}^2$.

• Journal of KIISE
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• v.45 no.3
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• pp.303-310
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• 2018

LoRaWAN(Long Range Wide Area Network) is a standard for low-power, long-range, low-speed communication as announced in the LoRa Alliance. LoRaWAN addresses the physical layer and medium access control layer and the technology used in the physical layer is referred to as LoRa. LoRa can be used for remote monitoring and remote control in maritime conditions. However, unlike land, marine environment is not only difficult to construct an infrastructure for service provision, but also difficult to analyze LoRa performance in maritime. In this study, we construct an infrastructure using cloud platform and analyze LoRa link performance in maritime conditions.

• Journal of electromagnetic engineering and science
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• v.2 no.1
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• pp.56-58
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• 2002

In this paper, the double conversion gate mixer using a half-LO frequency is described at 25 GHz band. The proposed mixer uses two HEMTs excited by a single LO signal of half-LO frequency in order to generate the second IF signal. That is, the LO signal having the half-LO frequency is only fed into the gate of the first HEMT mixer as a normal gate mixer. The LO signal through the first mixer is find into the second mixer The proposed miler requires not only half of the normal LO frequency, but also lower LO power than the conventional subharmonically pumped milers. Over the bandwidth of 500 MHz at 24.5 GHz, the conversion gain is 2.5 dB, the noise figure is 9 dB, and the isolation between RF and LO port is 32 dB when the LO poller is 0 dBm at 12.65 GHz.