• Korean Journal of Optics and Photonics
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• v.18 no.2
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• pp.93-99
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• 2007

We investigated analytically and numerically the occurrence of modulation instability in fibers with periodic changes both in dispersion and gain. Previously, it has been known that the modulation instability is suppressed in dispersion managed solitons where dispersion is managed in such a way that the local dispersion alternates between the normal and the anomalous regimes. In this work, we enhanced the advantage of the dispersion management scheme by additionally introducing proper gain/loss profiles in fibers. The gain/loss profile is given by $\Gamma(z)=0.5/D(z)*(dD/dz)$, where D(z) represents the dispersion profile. The fundamental gain spectra of the modulation instability in the dispersion and gain managed fibers have been derived analytically and confirmed by numerical calculation. Our investigation reveals that in the dispersion and gain fibers the modulation instabilities are always much more suppressed compared to the case with only dispersion managed. In practical dispersion management schemes, dispersion profiles show discontinuity. and thus. the corresponding gain/loss profiles tend to be finite. In these cases, the gain/loss profiles were approximated by lumped gains/losses of finite values. Our numerical calculations confirm that this approximation also works well.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.3
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• pp.453-460
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• 2019

The SR-DCSK(Short Reference Differential Chaos Shift Keying) is a variant of DCSK that improves data transmission speed and energy efficiency without additional complexity. However, even when the reference signal of the optimum length is applied, the BER performance of the SR-DCSK is not better than that of the conventional DCSK. In this paper, we propose a scheme to improve the performance of SR-DCSK by applying two scale factors (scale coefficients) to the reference signal and the information signal, respectively. And the performance of the proposed method is analyzed by BER using Gaussian Approximation. Based on the derived BER expressions, we minimize the BER for a given system parameter to optimize the ratio of the two coefficients. Simulation results confirm that the BER of the proposed method is much improved over the SR-DCSK when we apply the optimal ratio of the two scale factors.

• Plant Journal
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• v.18 no.2
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• pp.41-45
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• 2022

The conventional communication method using mud flow pressure waves has a speed of 1-2 bps, so it takes a long time to communicate, making real-time control impossible. Although the sound wave communication method for improving the communication speed by 10 times or more has been commercialized, its use is limited due to its high price and there are not many application cases. In this study, the simulator corresponding to the facility was developed to develop performance similar to the actual test results. For simulating sound wave communication through a drill pipe, we proposed a governing equation that can simulate friction damping by mud and developed a numerical analysis model. The attenuation factor was corrected by comparing it with the attenuation rate of sound wave energy at the drilling site. The developed numerical analysis model was applied to the QPSK modulation type communication algorithm to confirm the excellent performance of the communication error rate of 0.04% in the ground. This is the communication performance under the condition that noise has not been mixed yet, and in order to apply it, the technology of reproducing the actual noise signal for mixing by securing the field noise data was established.

• Journal of the Korean Magnetics Society
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• v.2 no.3
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• pp.251-256
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• 1992

Artificial superlattices of Co/Pd were prepared by RF magnetron sputtering Multilayered structure and compositional modulation were analyzed with a side angle x-ray diffractometer. It has been found that expansion of Co lattice occured in this artificial superlattice due to the lattice mismatch between Co and Pd. Perpendicular magnetic anisotropy could be observed when the Co layer thickness became less than 8${\AA}$ and maximum coercivity of 2350 Oe could be obtained in [Co(2.5 ${\AA}$)/Pd(9.3 ${\AA})]_{50}$/Pd$(200\;{\AA})$ with a perfect squareness of magnetic hysteresis loop. Characteristic of perpendicular magnetic anisotropy in Co/Pd superlattices could be related to the expansion of Co lattice caused by Pd layer and it turned out that as the thickness of Pd layer increased, perpendicular magnetic anisotropy increased. The interface anisotropy energy and volume anisotropy energy were calculated to be 0.29 ergs/$cm^2$ and -$6.9{\times}10^6$ ergs/$cm^3$ respectively, which are consistent with the values reported elsewhere.

• Smart Media Journal
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• v.7 no.4
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• pp.52-60
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• 2018

Energy Management System(EMS) of Microgrid(MG) collects and analyzes data from devices in the microgrid to provide information to operators, users and other systems. In the middle of the process, it is required to securely provide information through both wired and wireless communication networks. In this paper, we design and implement a module that provides encryption and decryption, key management, key distribution, and message authentication functions, thus enabling the development of a system which is safe from the exposure and modulation of data potentially occurrable during data transmission between RTU(Remote Terminal Unit) and EMS. Our method can increase the efficiency of connection and key management for RTU by connecting a virtual device(VD) to RTU.

• Convergence Security Journal
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• v.18 no.3
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• pp.77-85
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• 2018

With the convergence of communications network between control system and public network, such threats like information leakage/falsification could be fully shown in control system through diverse routes. Due to the recent diversification of security issues and violation cases of new attack techniques, the security system based on the information database that simply blocks and identifies, is not good enough to cope with the new types of threat. The current control system operates its security system focusing on the outside threats to the inside, and it is insufficient to detect the security threats by insiders with　the authority of security access. Thus, this study conducted the importance analysis based on the main event log list of "Spotting the Adversary with Windows Event Log Monitoring" announced by NSA. In the results, the matter of importance of event log for the detection of insider threats to control system was understood, and the results of this study could be contributing to researches in this area.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.2
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• pp.1-12
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• 2023

In the current era of the global mobile smart device revolution, electronic devices are required in all spaces that people interact with. The establishment of the internet of things (IoT) among smart devices has been recognized as a crucial objective to advance towards creating a comfortable and sustainable future society. In-mold electronic (IME) processes have gained significant industrial significance due to their ability to utilize conventional high-volume methods, which involve printing functional inks on 2D substrates, thermoforming them into 3D shapes, and injection-molded, manufacturing low-cost, lightweight, and functional components or devices. In this article, we provide an overview of IME and its latest advances in application. We review biomimetic nanomaterials for constructing self-supporting biosensor electronic materials on the body, energy storage devices, self-powered devices, and bio-monitoring technology from the perspective of in-mold electronic devices. We anticipate that IME device technology will play a critical role in establishing a human-machine interface (HMI) by converging with the rapidly growing flexible printed electronics technology, which is an integral component of the fourth industrial revolution.

• The Journal of Korean Society for Radiation Therapy
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• v.30 no.1_2
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• pp.17-25
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• 2018

Purpose : To compare the radiation doses of prostate cancer patients according to changes in abdominal body shape and energy during Volumetric modulated arc therapy(VMAT). Materials and Methods : Seven patients with prostate cancer were enrolled in this study. VMAT treatment plan was established at 6, 10, and 15 MV while changing from -2.0 cm to 2 cm by 0.5 cm. Conformal index(CI), homogeneous index(HI), $D_{max}$, $D_{95%}$, $D_{50%}$ and $D_{2%}$ of PTV were examined in order to evaluate the change of dose in the target organ according to body shape change. Normal organ of the femoral head, rectum and bladder was analyzed to evaluate dose changes. Results : The dose of $D_{max}$ 6 MV in PTV increased to 107.2 % in 1.0 cm body shape reduction, and 10 MV and 15 MV dose increased to 107.1 % and 107.0 % in 1.5 cm body reduction, respectively. The dose of $D_{50%}$ 6 MV in PTV decreased to 99.64 % in 1.0 cm body shape increase, and in 10 MV and 15 MV dose decreased to 99.79 % and 99.97 % in 1.5 cm body increase, respectively. In 2.0 cm body type increase, the dose was decreased to 99.30 % and 99.52 %, respectively. Doses for rectum and bladder gradually increased with decreasing weight, and dose decreased with decreasing weight. 6 MV, and $V_{70Gy}$ at 10 MV increased from 11.50 % to 12.76 % when the external shape decreased by 2.0 cm. The bladder $V_{70Gy}$ also increased from 14.0 % to 15.2 %. It was also shown that the dose increased as the body weight decreased in the femoral head. Conclusion : In the treatment of VMAT, dose distribution can be changed according to the change of abdominal shape. SSD and CBCT were used to decrease the body shape by more than 1cm or more than 1.0 cm at 6 MV and the body shape by more than 1.5 cm or more than 1.5 cm at 10 MV or 15 MV. It is considered that a new treatment plan should be established through re-simulation.

• Journal of Digital Convergence
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• v.14 no.5
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• pp.333-339
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• 2016

Technology to optimize and utilize the use and supply of the electric power between consumer and supplier has been on the rise among the smart grid power market network in electric power demand management based on the Internet. Open Automated Demand Response system protocol, which can deliver Demand Response needed in electric power demand management to electricity supplier, system supplier and even the user is openADR 2.0b. This paper used the most credible, cosmopolitanly proliferated EPRI open source and analysed the variety of security vulnerability that developed VEN and VTN system may have. Using the simulator for attacking openADR protocol, the VEN/VTN system that has been implemented as EPRI open source was conducted to attack in a variety of ways. As a result of the analysis, we were able to get the results that the VEN/VTN system has security vulnerabilities to the parameter tampering attacks and service flow falsification attack. In conclusion, if you want to implement the openADR2.0b protocol system in the open or two-way communication environment smart grid network, considering a variety of security vulnerability should be sure to seek security technology and services.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.607-615
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• 2016

This study concerns the transmission of energy and data using induced electromotive force. Due to the requirements of weapon systems, most arms are kept in an armory for a very long time before being used. During this time, the reserve battery, which serves mostly as a power supply for the electronic fuze, can be degraded, thus causing problems when it is actually needed. We attempt to solve the various problems associated with the old fuze system caused by long-term storage by using the 'induction power' transmitted from another device just before its operation, instead of using 'built-in power'. We tried to find the best carrier frequency to communicate with the system by induced electromotive force. Also, we changed the communication method for transmitting the 'induction power' from 'FM/AM modulation' to 'Duty ratio modulation', which can transmit a large amount of data in a short time. Through experiments, it was demonstrated that the induction coil can replace the reserve fuze's battery without any problem, thus confirming the possibility of using an induction coil as the power supply source of the electronic fuze.