• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.4
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• pp.539-544
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• 2011

Balanced binary sequences of period $2^n-1(n{\geq}1)$ having the two-valued autocorrelation function have many applications in spread-spectrum communications system. In this paper we propose new nonlinear binary sequences which are constructed from Legendre sequences with the same cross-correlation as the sequences proposed by Cho. These sequences include the m-sequences, GMW sequences, Kasami sequences and No sequences which are described in terms of the trace function over a finite field. Also the proposed sequences have more low cross-correlation distribution than the quadratic form sequences proposed by Klapper.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.4
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• pp.853-871
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• 2012

The location based service is divided into GPS that uses the artificial satellite or base transceiver station in order to cover the wide area and RTLS(Real Time Location System) using the Zigbee, RFID, CSS(Chirp Spread Spectrum), UWB, Bluetooth and Wi-Fi equipment in the space(close range) limited like the building inside or park. Moreover it also repeats the technical development upon through the acceleration of the development of the wire and wireless infrastructure and determination technology, the development of the Internet, diversification of the contents, and etc. As a result, it is expected to develop around the determination technology, witch is common core technology element, contents technology, Internet and mobile communication technology, and etc. afterward. In this research, the direction we investigate was to find and analyze new technology and standardization trend of LBS in order to contribute to the related industry.

• Journal of Broadcast Engineering
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• v.6 no.1
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• pp.13-20
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• 2001

In this paper, we propose a new digital audio watermarking scheme In the cepstrum domain. We insert a digital watermark signal Into the cepstral components of the audio signal using a technique analogous to spread spectrum Communications, hiding a narrow band signal in a wade band channel. In our proposed method, we use pseudo-random sequences to watermark the audio signal. The watermark Is then weighted in the cepstrum domain according to the distribution of cepstral coefficients and the frequency masking characteristics of the human auditory system. The proposed watermark embedding scheme minimizes audibility of the watermark signal. and the embedded watermark is robust to mu1tip1e watermarks, MPEG audio ceding and additive noose.

• Journal of Korea Multimedia Society
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• v.9 no.3
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• pp.333-341
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• 2006

Recently, Random Constant worm is increasing The worm retards the availability of the overall network by exhausting resources such as CPU resource and network bandwidth, and damages to an uninfected system as well as an infected system. This paper analyzes the Power-Law network which possesses the preferential characteristics to restrain the worm from spreading. Moreover, this paper suggests the model which dynamically controls the spread of the worm using information about depth distribution of the delivery node which can be seen commonly in such network. It has also verified that the load for each node was minimized at the optimal depth to effectively restrain the spread of the worm by a simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.7
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• pp.1234-1243
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• 1994

We propose an adaptive decoding scheme for a concatenated codes with frequency-hopped spread-spectrum communication system in the presence of a pulse-burst jammer and its performance is analyzed. Concatenated coding system employing binary inner code and Reed-Solomon outer code is investigated and the use of side information is allowed to decode both erasures and errors. Our scheme makes the decoder adapts to the level of jamming by switching between two decoding modes such that the overall block error probability can be reduced. It is shown that the proposed decoding scheme yields a significant performance improvement over a conventional decoding scheme.

• Journal of Power Electronics
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• v.13 no.4
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• pp.619-625
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• 2013

Switched mode power supplies (SMPS) are power electronic circuits extensively used in a wide range of applications. High frequency switching operation of SMPS causes electromagnetic emissions and has the potential to interfere with system operation, which in turn has an impact on system performance. This makes electromagnetic compatibility (EMC) an important concern. In this paper, a new and simple spread spectrum technique is proposed by modulating chaotic pulse position modulation (CPPM) and pulse width modulation (PWM). The resulting CPWM is implemented to reduce the conducted EMI in SMPS. The proposed method is found to be effective in reducing conduction EMI. The effectiveness and simplicity of the proposed method on spreading those dominating frequencies is compared to the EMI mitigation technique using an external chaotic generator. Finally, the levels of conductive EMI with standard PWM, CPWM with an external chaos generator and the proposed method are experimentally verified to comply with the CISPR 22A regulations. The results confirm the effectiveness of the proposed method.

• Information and Communications Magazine
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• v.13 no.11
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• pp.181-191
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• 1996

In this paper we discuss narrow-band interference rejection schemes for spectrum overlay communications where direct sequence spread spectrum (DS/SS) communication system and narrow-band communication systems share the same frequency band. In this case, it is essential to reject the narrow-band signals to guarantee the performance of DS/SS system, while it is not necessarily required to reject the DS/SS signal to recover the narrow-band signal. We discuss several schemes such as time domain processing, frequency domain processing and exploiting the device characteristics to reduce the effect of narrow-band signal on DS/SS communication systems. Furthermore, we suggest a structure of tunable notch filter using gyrator that can easily be customized to ASIC.

• International Journal of Computer Science & Network Security
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• v.22 no.2
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• pp.199-208
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• 2022

The world health organization classified the emerging coronavirus (known as Covid-19) as a pandemic after confirming the extent of spread and scale. As a matter of fact, outbreaks of similar scale or even worse have been witnessed throughout history. Thus, the development of prevention strategies exists to protect against such calamaties. One of the widely proven measures that controls the spread of any contagious diseases is social distancing. As a result, this paper will demonstrate the concept of an application "Be Aware" on enabling the implementation of this preventive measure. In particular "Be aware" evaluates the extent of congestion in public places using current time data. The proposed project will use Global Positioning System (GPS), and Application Programming Interface (API), to ensure information accuracy, and the API use Crowdsourcing to collect Real-Time Data (RTD) from the selected places. One line

• Journal of Information Technology Services
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• v.20 no.6
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• pp.151-162
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• 2021

Since 2012, the Navy has been conducting a defense experiment project to evaluate the possibility of military application by introducing new technologies related to excellent private informatization in the defense field. There are many projects that have spread because they are suitable for military use, but some have ended as experimental projects themselves because they do not meet the military's required performance. Continuous development is required as increasing the spread rate by successfully carrying out defense experiment projects is the basis for defense reform. This study analyzed the performance of major projects carried out by the Navy and presented considerations for the development of defense experiment projects to be carried out by the Navy in the future. The main achievements were derived in various ways in terms of project performance and system operation, and the considerations can be summarized in the field of raising business requirements, securing resources for system operation, determining the size of companies for project execution, and security measures. The research results can be used as data to determine the required defense experiment project and efficiently carry out the project.

• Journal of Forest and Environmental Science
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• v.40 no.1
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• pp.24-34
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• 2024

Fire, being primarily a natural phenomenon, is impossible to control, although it is feasible to map the forest fire risk zone, minimizing the frequency of fires. The spread of a fire starting in any stand in a forest can be predicted, given the burning conditions. The natural cover of the land and the safety of the population may be threatened by the spread of forest fires; thus, the prevention of fire damage requires early discovery. Satellite data and geographic information system (GIS) can be used effectively to combine different forest-fire-causing factors for mapping the forest fire risk zone. This study mainly focuses on mapping forest fire risk in the Madikhola watershed. The primary causes of forest fires appear to be human negligence, uncontrolled fire in nearby forests and agricultural regions, and fire for pastoral purposes which were used to evaluate and assign risk values to the mapping process. The majority of fires, according to MODIS events, occurred from December to April, with March recording the highest occurrences. The Risk Zonation Map, which was prepared using LULC, Forest Type, Slope, Aspect, Elevation, Road Proximity, and Proximity to Water Bodies, showed that a High Fire Risk Zone comprised 29% of the Total Watershed Area, followed by a Moderate Risk Zone, covering 37% of the total area. The derived map products are helpful to local forest managers to minimize fire risks within the forests and take proper responses when fires break out. This study further recommends including the fuel factor and other fire-contributing factors to derive a higher resolution of the fire risk map.