• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.5
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• pp.681-687
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• 2017

This paper presents about an implementation of Video Transmitting and Receiving System(VTRS) for acquiring test data. The VTRS consists of two parts. The first is Transmitter Unit(TU) that is installed on a missile to acquire various kinds of data and transmit the data to the ground through RF signals. The second is Receiver Unit(RU) that receives the transmitted RF signals and reconstruct those to the original data. To gather a high speed data reliably and securely on the ground, the TU is designed by considering data transfer scheme, data compression, modulation method, encryption technic, link budget, and antenna radiation pattern. Further, a placement method of multiple receiving stations is suggested. The VTRS has been tested on a field to check the link margins and maximum receiving distance in a real environment. Finally, the VTRS is applied to a missile flight test and gathered high speed data reliably.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.10
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• pp.5116-5131
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• 2017

This paper studies the radio frequency to direct current (RF-DC) conversion efficiency of rectennas applicable to wireless power transfer systems, where multiple receive antennas are arranged in serial, parallel or cascaded form. To begin with, a 2.45 GHz dual-diode rectifier is designed and its equivalent linear model is applied to analyze its output voltage and current. Then, using Advanced Design System (ADS), it is shown that the rectifying efficiency is as large as 66.2% in case the input power is 15.4 dBm. On the other hand, to boost the DC output, three composite rectennas are designed by inter-connecting two dual-diode rectifiers in serial, parallel and cascade forms; and their output voltage and current are investigated using their respective equivalent linear models. Simulation and experimental results demonstrate that all composite rectennas have almost the same RF-DC conversion efficiency as the dual-diode rectifier, yet the output of voltage or current can be significantly increased; in particular, the cascade rectenna obtains the highest rectifying efficiency.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.4
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• pp.768-773
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• 2010

In this paper, we study on an optimal design of a triple-band PIFA (Planar Inverted-F Antenna) of 433 MHz, 912 MHz and 2.45 GHz by using evolution strategy. Generally, the resonant frequency of the PIFA is determined by the width and length of a U-type slot used. However the resonant frequencies of the multiple U slots are varied by the mutual effect of the slots. Thus the optimal width and length of U-type slots are determined by using an optimal design program based on the evolution strategy. To achieve this, an interface program between a commercial EM analysis tool and the optimal design program is constructed for implementing the evolution strategy technique that seeks a global optimum of the objective function through the iterative design process consisting of variation and reproduction. The resonant frequencies of initial model are 439.5 MHz, 981.5 MHz and 2.563 GHz. However, the resonant frequencies of the triple-band PIFA yielded by the optimal design program are 430.5 MHz, 907 MHz and 2.4515 GHz. Measured resonant frequencies are 433.5 MHz, 905.5 MHz and 2.454GHz, which show a good agreement with the simulation results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.4
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• pp.331-341
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• 2002

It is expected that the SCM (Subcarrier Multiplexing) optical link system, in which a number of small scale base stations with only antenna and RF transceiver are connected to central station through optical fiber, is in demand. In order to analyze the performance of SCM optical link system fur RF signal transmission, MZ(Mach-Zehnder) modulator's transfer function is modelled as nonlinear form with the cube of input signal. And considering the multiple access interferences occurred In the demodulation of other users'CDMA signals with multipath components after passing through MZ modulator, the BER performance is analyzed.

• BMB Reports
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• v.48 no.12
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• pp.647-654
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• 2015

Energy homeostasis in our body system is maintained by balancing the intake and expenditure of energy. Excessive accumulation of fat by disrupting the balance system causes overweight and obesity, which are increasingly becoming global health concerns. Understanding the pathogenesis of obesity focused on studying the genes related to familial types of obesity. Recently, a rare human genetic disorder, ciliopathy, links the role for genes regulating structure and function of a cellular organelle, the primary cilium, to metabolic disorder, obesity and type II diabetes. Primary cilia are microtubule based hair-like membranous structures, lacking motility and functions such as sensing the environmental cues, and transducing extracellular signals within the cells. Interestingly, the subclass of ciliopathies, such as Bardet-Biedle and Alström syndrome, manifest obesity and type II diabetes in human and mouse model systems. Moreover, studies on genetic mouse model system indicate that more ciliary genes affect energy homeostasis through multiple regulatory steps such as central and peripheral actions of leptin and insulin. In this review, we discuss the latest findings in primary cilia and metabolic disorders, and propose the possible interaction between primary cilia and the leptin and insulin signal pathways which might enhance our understanding of the unambiguous link of a cell's antenna to obesity and type II diabetes.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.111-114
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• 2003

It has well known that MUSIC and ESPRIT algorithms estimate angle of arrival(AOA) with high resolution by eigenvalue decomposition of the covariance matrix which were obtained from the array antennas. In the case that 2-D large-sized array antenna is required, however, one of the disadvantages of MUSIC and ESPRIT is that they are computationally ineffective, and then they are difficult to implement in real time. To alleviate the computational complexity, several method using neural model have been study. For multiple signals, those methods require huge training data prior to AOA estimation. This paper proposes the algorithm for AOA estimation by interconnected hopfield neural model. Computer simulations show the validity of the proposed algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.6
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• pp.1283-1288
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• 2015

In general, IC chip circuit which is operating a cryptographic computation tends to radiate stronger electromagnetic signal to the outside. By using a power detecter such as a loop antenna near cryptographic device, the encryption key can be identified by probing a electromagnetic signal. To implement a method against non-invasive type attack, multi dielectric slab structure on IC chip to suppress radiated electromagnetic signal was introduced. Multiple dielectric slab was implemented by suitably configured to have the Bragg reflection characteristics, and then the reflection response was computed and verified its effectiveness. As a result, the thickness of the dielectric coating was 2mm and the reflection response characteristics for the vertical incidence was achieved to be 91% level.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.2
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• pp.491-496
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• 2010

This paper describes an analysis of the effectiveness for an anti-ARM technique to protect a radar system. We investigate the optimum deployment of decoy antennas which are widely using for anti-ARM and the electromagnetic field at the ARM receiver. To verify the effect of decoy antennas, we analyze the field intensity and phase at the receiver and develop a numerical simulation program using Matlab. We conduct an analysis of ARM attack in case of using multiple decoy antennas and these results can be used to decide the optimum positions of the decoys for anti-ARM.

• Journal of Satellite, Information and Communications
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• v.11 no.3
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• pp.86-91
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• 2016

KARI(Korea Aerospace Research Institute) has been developing the KPLO(Korea Pathfinder Lunar Orbiter) for Korean first lunar exploration, and analysing various subjects for the mission success. Especially the performance of the communication is one of important factors, because massive scientific and technical data acquired by multiple payloads might be transferred to ground stations on the Earth. In this paper, we explained the study on the 1-day average downlink capacity based on the visibility analysis between ground stations and KPLO, and described its results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.1
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• pp.98-105
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• 2011

Reduced complexity codebook searching for Quantized Equal Gain Transmission(QEGT) is proposed over MIMO-OFDM systems. QEGT codebook is divided into M groups of Q index members. Each group has a representative index. At the 1st stage only the representative indices are searched then the best index is selected. At the 2nd stage the optimum index is determined only among the group of the selected representative index. This strategy reduces the overall index search algorithm comparing to the conventional methods. Monte-Carlo simulation shows that the searching complexity is reduced, but the link-level performance is still almost the same as the conventional methods when the number of transmission antennas are 3 to 7.