• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.1
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• pp.54-62
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• 1988

For code division multiple access, a frequency synthesizer of elementary components is necessary in the system application of frequency hopped spread spectrum communication. This paper proposes the model of N-loop PLL frequency synthesizer to be adaptied for generating the output frequency resultes in the frequency hopping pattern and to be easy in practical application of the system. It was analyzed how the frequency divider ratio distribute, what the method to decide frequency divider ratio is and what relationship of bandwidth of BPF and degree of multiple have is also analyzed in order to hop the desired frequency output.

• Journal of Satellite, Information and Communications
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• v.9 no.2
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• pp.80-84
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• 2014

As an integrated technology with IT and biomedical sciences, U-health offers various healthcare services without time and space limit. In order to make a proper diagnosis, doctors need two key technologies: biosignal measurement and high reliability communication technologies. In this paper, we introduce an implementation process of a bio signal system with using an electrocardiography(ECG) sensor, video, global positioning system(GPS), communication module and micro controller unit(MCU).

• Journal of Power Electronics
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• v.10 no.4
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• pp.335-341
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• 2010

In this paper, an interleaved soft switching boost converter for a Photovoltaic Power Conditioning System (PV-PCS) with high efficiency is proposed. In order to raise the efficiency of the proposed converter, a 2-phase interleaved boost converter integrated with soft switching cells is used. All of the switching devices in the proposed converter achieve zero current switching (ZCS) or zero voltage switching (ZVS). Thus, the proposed circuit has a high efficiency characteristic due to low switching losses. To analyze the power losses of the proposed converter, two experimental sets have been built. One consists of normal devices (MOSFETs, Fast Recovery (FR) diodes) and the other consists of advanced power devices (CoolMOSs, SiC-Schottky Barrier Diodes (SBDs)). To verify the validity of the proposed topology, theoretical analysis and experimental results are presented.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.2
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• pp.40-46
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• 2022

Recently, as the need for data access by integrating information in a distributed cloud environment increases in enterprise-wide enterprises, interoperability for collaboration between existing legacy systems is emphasized. In order to interconnect independent legacy systems, it is necessary to overcome platform heterogeneity and semantic heterogeneity. To solve this problem, middleware was built using EMRA (Extended MetaData Registry Access) based on ISO/IEC 11179. However, the designed middleware cannot guarantee the efficiency of information utilization because it does not have an adjustment function for each node's resource status and work status. Therefore, it is necessary to manage and adjust the legacy system. In this paper, we coordinate the correct data access between the information requesting agent and the information providing agent, and integrate it by designing a cooperative agent responsible for information monitoring and task distribution of each legacy system and resource management of local nodes. to make efficient use of the available information.

• Nuclear Engineering and Technology
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• v.47 no.5
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• pp.624-632
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• 2015

A self-diagnostic monitoring system is a system that has the ability to measure various physical quantities such as temperature, pressure, or acceleration from sensors scattered over a mechanical system such as a power plant, in order to monitor its various states, and to make a decision about its health status. We have developed a self-diagnostic monitoring system for an air-operated valve system to be used in a nuclear power plant. In this study, we have tried to improve the self-diagnostic monitoring system to increase its reliability. We have implemented three different machine learning algorithms, i.e., logistic regression, an artificial neural network, and a support vector machine. After each algorithm performs the decision process independently, the decision-making module collects these individual decisions and makes a final decision using a majority vote scheme. With this, we performed some simulations and presented some of its results. The contribution of this study is that, by employing more robust and stable algorithms, each of the algorithms performs the recognition task more accurately. Moreover, by integrating these results and employing the majority vote scheme, we can make a definite decision, which makes the self-diagnostic monitoring system more reliable.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.12
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• pp.115-121
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• 2008

The communication-based train control (CBTC) technology is a kind of railway signaling technologies and is to control the train operation through communication. A project adopting the CBTC technology is in progress and its object is to develop interoperable and interchangeable subsystems. Thus the purpose of this paper is on how to develop the required subsystems and integrate them successfully without sufficient design information at the system level. Accordingly this project shall require the integration and test at the system level. In order to do so, a top-level system specification shall be needed, which is not available in the current phase of the project. The main objective of the test and evaluation activities is to see whether the developed system meets the system specification. In this paper, we describe how the test and evaluation can be carried out based on the subsystems design specifications, considering the system architecture and the operation concept of the existing system as well.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.152-161
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• 2022

Recently, it is recognized as a high-cost and inefficient logistics system that increases traffic congestion and environmental problems due to an increase in traffic volume due to the activation of the online market. In order to solve inefficient problems such as unavoidable traffic congestion and environmental problems caused by the increase in traffic volume, it is necessary to develop a freight transport system technology using the existing urban railway infrastructure and freight-only urban railway. The urban subway logistics system is a logistics system that requires a combination of various technologies to solve the nationwide demand for urban logistics and road traffic problems. This paper recognized the existing traffic congestion and environmental pollution of road traffic as problems, and supplemented the contact point requirements presented above by identifying the sub-systems constituting the target system and supplementary points for each part-level contact point. In this study, as a complex system operated for one purpose by grafting various technologies, a plan is required to secure the reliability and safety of operation from various viewpoints. The results of this study can contribute to the initial configuration and basic data to solve the interface bottleneck of the urban subway logistics system to be promoted in the future.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.11-12
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• 2012

In this paper, efficient visible light communication technology LED (Light Emitting Diode) lighting through the existing infrared sensor used for performance analysis of transmitting and receiving is possible. LED utilizes lighting by changing light into electricity. Lighting features while maintaining the basic principles of flashing LED and PD (Photo Diode) to send and receive communications from LED lighting communication convergence principle be realized simultaneously enabling. Multiple IT applications under the basic structure of LED technology development, and the current was encountered in real life. LED lighting anywhere with wireless communication technology that can, in order to ~ 1m above the initial value by taking advantage of the system H/W and infrared sensors(PD) are widely used in the entire system that can improve the speed of visible light data transmission system is finished. LED module that is used to communicate whether the performance analysis, For forecasting and communication distance on the LED and infrared sensor configuration of the implementation of the research is to study about the possibility of application methods and indicates.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.2
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• pp.231-236
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• 2020

In today's society, the majority of people use smartphones, and mobile ordering and payment systems for their convenience are gaining their attention. The mobile payment market is on the rise, with over 71% of the market that is already formed in China. Many mobile payment markets are growing in Korea, which is a system that is provided only in large franchises. In this paper, we propose a mobile ordering and payment system using short-range wireless communication technology that can be easily used not only in franchises but also in the small businesses, and for the convenience of users in modern society to make a system that enables ordering and payment through mobile to communicate between the devices developed by short range wireless communication technology, smartphone and the main server.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.5
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• pp.181-186
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• 2008

Wireless data transmission is vulnerable to attackers and hackers. Recently, the fast development of wireless communication systems seamlessly increase the demand for security in this area. Moreover, error correction is especially important because various kinds of interferences among wireless devices. In order to solve two above problems, we propose to apply MCC (M-sequence Convolutional Code) in the system which is able to protect information and correct errors. The proposed system can obtain higher secure property by randomly changing the output connections by the proposed M-sequence. Performance of the system is analyzed according to BER (Bit Error Rate) and secure levels. The simulation results revealed that we can get the coding gain of 0.1 dB over conventional convolution coding technique. The proposed algorithm is installed in physical layer and easily implemented. Another advantage of our proposed (M-sequence and convolutional code) is that it can be applied to CDMA (Code Division Multiple Access) communication system.