• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.10
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• pp.60-66
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• 2011

In this paper, we analyze the effects of estimation error in the active cancellation signal, which is intended to counter the pulsed-CW signal of a hostile radar. We also examine the effects of estimation error in maximum-likelihood estimation (MLE) and quadratic interpolation scheme from a radar signal active cancellation viewpoint. Then, we modify the correlation-based error compensation scheme which mitigates the estimation error of MLE to improve the performance of the active cancellation signal. Finally, we present simulation results to show that the correlation-based scheme has better performance than the other in terms of radar signal active cancellation.

• Journal of the Korean Magnetics Society
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• v.2 no.2
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• pp.156-162
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• 1992

In the measurement of proton gyromagnetic ratio by a low field cechnique, the compensation of earth's field is required to keep a zero-field space. The constant earth's fild is compensated by a cur-rent flowing through a Helmholtz coil, whereas small time-varying component is compensated automatically by a closed loop of feedback system. A feedback amplifier, and two three-dimensional Helmholtz coils having the same coil constant have been constructed in order to compensate the earth's field. field. Preliminary test performed at the ordinary laboratory showed that the time-vary-ing field of ${\pm}100nT$ and the constant field have been reduced to the level of ${\pm}10nT$ using the compensating system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.8 s.99
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• pp.825-834
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• 2005

In this paper, a new signal canceller that input signals are equally group-delayed and cancelled each other is proposed and feedforward linearizing power amplifier that adopt the proposed signal cancellers is fabricated. Although the conventional signal canceller can't matches the phase and the group delay time of input signals simultaneously, the proposed signal canceller matches those simultaneously. Simultaneous matching of the phase and the group delay time can makes wideband signal cancellation. The main signal cancellation loop of the fabricated feedforward amplifier with the proposed signal cancellers cancel input signal more than 26.3 dB and the intermodulation distortion signal cancellation loop cancel more than 15.2 dB for 200 MHz bandwidth. And the proposed feedforward power amplifier improves C/I ratio by 20.8 dB with two tones at 2,115 MHz, 2,165 MHz, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5A
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• pp.543-550
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• 2011

In order to improve readability, a leakage-signal canceller has been proposed in UHF-band RFID readers. The proposed canceller is composed of two blocks: an environment monitoring block for detection of Tx and RX power levels and a leakage cancellation block. The leakage canceller consists of directional-couplers, digital attenuators and phase shifters based on the feed-forward scheme. The leakage canceller is located between antenna and reader. An improved experimental characterization of the scheme is presented with results from the reader operating in the Korean RFID frequency band, conforming the validity of the approach with more than 29 dB of leakage cancellation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1402-1405
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• 2016

In this paper, we develop an interference neutralization (IN) method based on a set of multi-antenna relays for K-user interference channel. The feasibility condition for IN is fully characterized. We further provide a relaxed IN method for the cases in which there are not enough relays to satisfy the feasibility condition.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.1
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• pp.88-94
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• 2019

A leakage canceller and adaptive algorithm for FMCW Radar is presented. Because a strong leakage signal causes various problems in the transceiver and digital processor, specific FMCW radars are in need of a leakage canceller. The leakage canceller has an adaptive structure and the algorithm calculates the prediction vector and learns the adaptive coefficient simultaneously. The proposed algorithm an improvement of 10 dB in the cancellation performance.

• Journal of Climate Change Research
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• v.1 no.2
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• pp.97-107
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• 2010

A forest project for the sequestration of carbon dioxide helps to reduce the concerntration of greenhouse gas in atmosphere and provides various co-benefits. A lot of forestry-based carbon offset programs have been developing for the purpose of CSR(Corporate Social Responsibility), voluntary GHG emission reduction, and regulatory context etc. in worldwide. We studied major characteristics - project type and criteria, additionality, credits, permanence, carbon accounting and monitoring, co-benefit - of advanced forest carbon offset programs. Also, we tried to comprehend the direction and basic elements to design a domestic program.

• Convergence Security Journal
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• v.16 no.3_1
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• pp.27-35
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• 2016

This thesis analyzes the backgrounds of the third offset strategy of the US Department of Defense. The key technology areas to be developed and the implications of the 3rd strategy are also examined. The potential great powers, China and Russia have catched up with US in the certain areas of military technologies. The technological superiority of US military is found to have been eroded. The US DOD needs a new defense policy called the 3rd offset strategy to meet this new challenge. The 5 basic technology areas were identified; learning machines, human-machine collaboration, machine-assisted human operations, human-machine combat teaming, and autonomous weapons. The 3rd offset strategy should be managed not to move to the new arms race with rivalries. The defense acquisition system also needs to be improved for the smooth flow of the advanced commercial technologies to the defense sector. Korea needs to figure out the possible technologies of co-research and development with US.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.6
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• pp.542-553
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• 2011

A magnetic cable that can safely deliver high frequency AC electric power in flammable or sensitive workplaces by preventing from arcs and electric shocks is firstly proposed in this paper. Several new magnetic cable structures with magnetic shields, which are composed of such cancel coil, cancel copper plate, and cancel copper pipe, were compactly implemented by considering and analyzing fringe field and thus the parallel leakage flux is drastically reduced. The output power and efficiency of a prototype magnetic cable with 1.5 m length and 5 cm gap were measured as 353.8W and 68%, where the source current and switching frequency were 10 $A_{rms}$ and 20 kHz, respectively. The proposed magnetic cables are fully analyzed and verified by finite-element method (FEM) simulations and experiments. The results are in a good agreement.

• Journal of Korean Society of Forest Science
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• v.101 no.1
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• pp.83-90
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• 2012

Forests as carbon sinks and sources, play an important role in mitigating global climate change. Nonpermanence problem of forest carbon offset projects should be addressed practically and properly for obtaining credible forest carbon credits. This study aims to analyze major non-permanence approaches and their applicability for Korean forest carbon offset projects. Introduction of the buffer system, one of the most generally used non-permanence approaches, should be considered first for domestic forest carbon offset schemes. From the research survey, experts preferred the buffer system to other approaches such as forest certification, conservation easement, and longer conservation period. Standard development including a buffer system with a risk assessment tool is required to assure project participation and permanence of carbon credits.