• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1995.05a
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• pp.171-175
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• 1995

Semiconductor diode lasers that can generate one watt or more of optical energy for tens of milliseconds (quasi continuous wave) are now readily available. Several researchers have demonstrated that this power level, when properly coupled, can reliably initiate pyrotechnic mixtures. This means that the initiator containing the pyrotechnic can be protected against inadvertent initiation from electromagnetic radiation or electrostatic discharge by a conducting Faraday cage surrounding the explosive. Only a small dielectric window penetrates the housing of the initiator, thereby eliminating the conductors necessitated by a bridgewire electroexplosive device. The diode laser itself, however, functions at a low voltage (typically 3 volts) and hence is susceptible to inadvertent function from power supply short circuits, electrostatic discharge or induced RF energy. The rocket motor arm-fire device de-scribed in this paper uses a diode laser, but protects it from unintentional function with a Radio Frequency Attenuating Coupler (RFAC).The RFAC, invented by ML Aviation, a UK company, transfers power into a Faraday cage via magnetic flux, thereby protecting the diode, its drive circuit and the pyrotechnic from all electromagnetic and electrostatic hazards. The first production application of a diode laser and RFAC device was by the Korean Agency for Defense Development.

• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.568-574
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• 2024

The development of radiation-tolerant radio-frequency (RF) systems can be a solution for applications in extreme radiation environments, such as nuclear power plant monitoring and space exploration. Among the crucial components within an RF system, the low noise amplifier (LNA) stands out due to its vulnerability to TID effects, mainly relying on transistors as its main devices. In this study, the TID effects in the LNA using standard 0.18 ㎛ complementary metal oxide semiconductors (CMOS) technology are estimated and analyzed. The results show that the LNA can withstand absorbed radiation up to 100 kGy. The S₂₁, S₁₁, noise figure (NF), stability (K), and linearity of the third input intercept point (IIP3) slightly shifted from the initial values of 0.8312 dB, 0.793 dB, 0.00381 dB, 1.34406, and 2.36066 dBm, respectively which are still comparable to the typical performances. Moreover, the standard 0.18 ㎛ technology has demonstrated its radiation tolerance, as it exhibits negligible performance degradation in the conventional LNA even when exposed to radiation levels up to 100 kGy. In this context, simulation approach offers a means to predict the TID effects and estimate the radiation exposure limit for electronic devices, particularly when transistors are used as the primary RF components.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.173-176
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• 2011

New paradigm is based on the e-navigation policy which is the harmonised collection, integration, exchange, presentation and analysis of maritime information onboard and ashore by electronic means to enhance berth to berth navigation and related services, for safety and security at sea and protection of the marine environment. One of the requirements is seamless communications between various communication systems. So we need the maritime wireless communications based on the SDR technology. In this paper we analyse characteristics and issues of maritime wireless communication technology and service framework and propose a SDR based maritime system platform which can operate in multi-mode.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.10 s.89
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• pp.1011-1017
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• 2004

Ultra Wideband(UWB) technologies have been developed to exploit a new spectrum resource in substances and to realize ultra-high-speed communication, high precision geolocation, and other applications. The energy of UWB signal is extremely spread from near DC to a few GHz. This means that the interference between conventional narrowband systems and UWB systems is inevitable. However, the interference effects had not previously been studied from UWB wireless systems to conventional mobile wireless systems sharing the frequency bands such as Korean Cellular CDMA and WCDMA. This paper experimentally evaluates the interference from two kinds of UWB sources, namely a direct-sequence spread-spectrum CDMA(DS-CDMA) UWB source and an impulse radio UWB source, to a Cellular CDMA and WCDMA digital transmission system. The average frame error rate degradation of each system are presented. From these experimental results, the interference effects of DS-CDMA UWB source is not severe compared to the Impulse UWB.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.3
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• pp.77-86
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• 2006

As a core technology in the ubiquitous environment, RFID (Radio Frequency Identification) technology takes an important role. RFID technology provides various information about objects or surrounding environment by attaching a small electronic tag on the object, thus, it means the remote control recognition technology. However, the problems which never happened before can be generated on the point of security and privacy due to the feature that RFID technology can recognize the object without any physical contact. In order to solve these problems, many studies for the RFID recognition technology are going on the progress. The currently running study is the secure communication channel between database and reader applying the recognition technology in the insecure communication channel between reader and tag. But, the purpose of this paper is to settle a privacy problem, which is insecurity of communication between database and reader channel by suggesting providing a user with authentication protocol in order to give information to an authorized entity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.740-748
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• 2016

IT and communication technologies has contributed significantly to the convenience of passengers and the financial management of stations in accordance with the task automation in the field of the urban railway system. The foundation of the above development is based on the large amounts of data from various sensors installed in railways, trains, and stations. In particular, the sensor network that is installed in the station and train has played an important role in the railway information system. The performance of AP is affected by the number of APs and their locations installed in the station. In the installation of APs in stations, the intensity of the radio wave of the AP on its underlying position is considered to determine the number and position of APs. This paper proposes a method to estimate the number of APs and their position based on the structure of the underlying station and implemented a simulator to simulate the performance of the proposed method. The implemented simulator was applied to the decision of AP installation at Busan Seomyeon station to evaluate its performance.

• Journal of the Korea Convergence Society
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• v.6 no.4
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• pp.1-7
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• 2015

This study is a case study of the research study and education with high school students of natural sciences. Recent development of the Internet of Things (IoT) based on the subject of various studies exist. This study is one of the most portable communication devices of these infancy, yet students were easy to define the molding process of contacting a pager that can go along way in making research topics. We called a pager. Today, it is given a large and complex smart mobile communication devices that can be used for big data. Prior pagers are taught the meaning of the first mobile communication means in our lives were given device. The internal structure is relatively simple and is thought to function relatively simple, just suitable as a teaching practices of high school students with an interest in science and engineering universities. This study can see all of the mechanical, electronic information contents of the radio pager in a relatively simple analysis of the injection molding ONE CAVITY analysis. Furthermore, the students also rated good educational practices that give meaning to remind the convergence training on mass production and process automation.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.1
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• pp.44-57
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• 2020

A dedicated short-range communications (DSRC) traffic information system is a detection system for a section of road using communication between roadside equipment and on-board High-Pass units to collect road traffic information and provide reliable traffic information to drivers. The Ministry of Land, Infrastructure, and Transport announced that a DSRC system must be supported to pass the performance evaluation of an intelligent transportation system (ITS), and the performance evaluation for DSRC systems installed in expressways and national highways is started. Currently, DSRC traffic information systems are only managed for maintenance and functional-monitoring purposes, which means that detailed criteria for the operation of a DSRC traffic information system, such as communication range, the direction of the antenna, and the power of the radio wave, etc., need to be established. In this paper, the criteria of the performance evaluation of a DSRC traffic information system are presented for different road types and road environments. The proposed performance evaluation criteria included the communication range and communication power of roadside equipment. In addition, installation criteria, such as the direction of the antenna, and the height and angle of the installed system, are presented for different road types and road environments. The criteria presented were evaluated for DSRC roadside equipment and documented to improve system maintenance and quality control of the communication system.