• Journal of the Optical Society of Korea
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• v.19 no.4
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• pp.371-375
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• 2015

The impact of equivalent optical bandwidth on the performance of a system using a reflective electroabsorption modulator (R-EAM) based optical source has been experimentally evaluated with signals operating at 2.5 Gb/s and beyond. The equivalent optical bandwidth of our source with a broadband seed light was simply adjusted by using a bandwidth tunable optical filter. From the measurements, we have estimated the required equivalent optical bandwidth of our source for an error-free transmission (@ bit-error-rate of $10^{-12}$) and a forward error correction (FEC) threshold of $2{\times}10^{-4}$.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.2
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• pp.87-92
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• 2014

This paper presents a new design for a piezoelectric energy harvester with the potential to harvest vibration energy over a wide range of excitation frequencies, particularly beyond the resonance frequency. The piezoelectric vibration energy harvester employs the concept of pole-zero cancellation occurring in a lever type anti-resonant system. The experimental results show that the proposed energy harvester can provide the potential possibility of a broadband piezoelectric vibration energy harvester.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.197-201
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• 2000

In this paper, a MMIC(Monolithic Microwave Integrated Circuit) broadband drive amplifier for wireless communication system has designed using active feedback method. The MMIC brodband amplifier was designed using 0.5$\mu\textrm{m}$ MESFET of ETRI library. Simulation results show that gain is 22 dB, and gain flatness ${\pm}$1 dB. Maximum output power 15 dBm and noise figure 2.5 dB in bandwidth 500 MHz ～3.0 GHz. The MMIC Broadband amplifer's chip area is 14mm${\times}$1.4mm.

• Journal of Auto-vehicle Safety Association
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• v.10 no.1
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• pp.12-19
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• 2018

This paper deals with the broadband electromagnetic emission test of a hybrid electric vehicle. The hybrid electric vehicle's powertrain system consists of an internal combustion engine and an EV traction motor. Depending on the SOC of the traction battery, these modes change automatically in the running state. The Korea electromagnetic compatibility regulations of KMVSS and UN WP.29 stipulated the evaluation method of hybrid electric vehicles. This study analyzes and compares two test results: internal combustion and electric motor mode. Some problems of test conditions are described and an improved test method is proposed for measuring broadband emissions of a hybrid electric vehicle. As a result, we expect this paper to be used as a consideration for improvement when test specifications are revised in the future.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.1 s.24
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• pp.33-40
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• 2006

A compact broadband active composite dipole antenna for direction finding system at the V/UHF-band is presented. It uses the composite structure which improves the antenna gain and the active circuit for broadband operation. This type of antenna has a high gain more than that of one dipole antenna within limited length(1m). The basic design and performance of both antenna structure and integrated active circuit are presented.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.9
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• pp.481-487
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• 2004

The Ku band that has been using for the satellite communication and broadcasting would be changed to K/Ka bands. The satellite system requires the antenna structure to fabricate low loss and small antenna that is able to be integrated with other Rf circuits for both Rx and Tx. So we should design it with dual feed antennas at K/Ka bands, high isolation between two different feeds and broadband circular polarization. This paper proposes the LTCC(Low Temperature Co-fired Ceramic) process for integration with other Rf circuits and the Axial mode of the helical antenna to satisfy those requirements.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.3
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• pp.250-256
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• 2002

In this paper, a broadband sleeve monopole antenna using a loading coil in sleeve is proposed. The center frequency of the proposed antenna is 1,990MHz. The antenna of the proposed structure has the same of the single sleeve monopole antenna, except for using the coil instead of the inner conductor in sleeve. As a result, it is found that the bandwidth is 1.239~2.154 GHz(above 53.9 %) for $S_{11}=-10\;d B$(VSWR<2), and the antenna impedance is good for a communication system and feeder which the impedance has 50 Ω.

• Journal of electromagnetic engineering and science
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• v.13 no.2
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• pp.63-72
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• 2013

The ultra-wideband (UWB) spectrum available for commercial applications has offered us an opportunity to achieve high-speed wireless communications and high-accuracy location applications. As one of key research areas in UWB technology, a lot of innovative broadband and miniaturization techniques for UWB antennas have been greatly invented and developed for years. This paper reviews the development of UWB antenna design in the past decade. Starting with a brief introduction of the specific requirements and promising applications of UWB systems, the unique design challenges of UWB antennas are highlighted. Next, the important milestones of UWB antenna designs are briefed. After that, a variety of planar UWB antennas invented for broadband operation, miniaturization, and multiple functions are introduced. Last, the comments on the development of UWB antennas in future are shared.

• ETRI Journal
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• v.28 no.3
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• pp.311-319
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• 2006

This paper presents a terminal-assisted frame-based packet reservation multiple access (TAF-PRMA) protocol, which optimizes random access control between heterogeneous traffic aiming at more efficient voice/data integrated services in dynamic reservation TDMA-based broadband access networks. In order to achieve a differentiated quality-of-service (QoS) guarantee for individual service plus maximal system resource utilization, TAF-PRMA independently controls the random access parameters such as the lengths of the access regions dedicated to respective service traffic and the corresponding permission probabilities, on a frame-by-frame basis. In addition, we have adopted a terminal-assisted random access mechanism where the voice terminal readjusts a global permission probability from the central controller in order to handle the 'fair access' issue resulting from distributed queuing problems inherent in the access network. Our extensive simulation results indicate that TAF-PRMA achieves significant improvements in terms of voice capacity, delay, and fairness over most of the existing medium access control (MAC) schemes for integrated services.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.6
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• pp.554-564
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• 2020

In environment of torpedo firing, underwater acoustic signal is generated by target and noise. Sound wave which is generated from acoustic signal is propagated by seawater and it is received through the sonar(sound navigation and ranging) system mounted on torpedo. In the ocean, acoustic signal or sound wave from target that is generated by the spread of broadband can be attenuated by ambient noise and can be lost by medium and environment. This research is designed to support teamwork training in Naval operations by constructing a simulation system that is more similar to the real-world conditions. This paper attempts to research the modeling of target detection and to develop the simulation of torpedo sonar(TOSO). In order to develop the realistic simulation, we researched the broadband sound modeling of target and noise source, the modeling of acoustic transmission loss by chemical component of seawater, and the modeling of signal attenuation by ambient noise environment which is approximated by experimental measurements in seawater surrounding the Korea Peninsular and by experience of Navy's actual torpedo firing. This research contributed to constructing more practical simulation of torpedo firing in real time and the results of this research were used to develop a teamwork training system for the Navy and their education.