• Fire Science and Engineering
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• v.25 no.6
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• pp.21-26
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• 2011

The purpose of this paper is to present the damage patterns of cellular phone (SCH_W830) batteries according to energy sources and have them utilized as data for the settlement of disputes between manufactures and consumers. The reliability was secured by maintaining the ambient temperature and humidity at $22{\pm}2^{\circ}C$ and 40~60 %, respectively. The voltage of the battery used for the tests was measured to be 4.18V between positive pole (+) and negative pole (-)(1), and 4.19 V between positive pole (+) and negative pole (-)(2). This study applied the Korean Industrial Standard (KS) to the flammability test of cellular phones due to a general flame applied to them and found that no damage occurred to the built-in battery even though the flame was applied to the cases of cellular phones for 30 seconds. From the results of immersing the cellular phones in the saline solution (NaCl, 0.9 %) for 180 seconds, it was found that there was a trace of carbonization and melting due to the heat caused by leaking current. It can be seen that when the cellular phones were heated for 70 seconds using a microwave oven (MWO), the areas containing the metal holder, recharging connector, antenna, etc., were melted and discolored and that other areas showed no particular problems. That is, while the external carbonization of cellular phones, built-in metals and dielectric materials, and damage and deformation of the battery terminal block, etc., occurred differently depending on the types of energy sources, the voltage showed comparatively constant characteristics. Therefore, it is thought to be possible to attribute the cause of damage to the battery by performing analysis taking into consideration comprehensively the characteristics of the flame spread pattern as well as the melting and deformation of metals.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.11
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• pp.12-20
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• 2013

Even though extensive research results have been applied to wireless cellular systems to improve their capacity and coverage, severe performance degradation experienced in cell boundary areas still remains as a major limiting factor to prohibit further improvement of user equipment (UE) throughput. In the Long Term Evolution-Advanced (LTE-A) standard of the Third Generation Partnership Project (3GPP), Some advanced techniques have been introduced to overcome this "cell-edge problem", including coordinated multipoint transmission and reception (CoMP) and inter-cell interference coordination (ICIC). In this paper, we propose yet another strategy to improve the performance of low-tier UEs by using the concept of multiple beam direction patterns (BDPs). Such multiple BDPs can be implemented using multi-layer antenna arrays stacked vertically at base station (BS) sites to transmit signals in different main beam directions. In comparison to conventional three-sector antennas with a fixed beam pattern, the proposed methods makes signal transmission in a rotational fashion to significantly enhance the reception quality of UEs located near sector (or cell) edge areas, preventing the situation where certain UEs are marginally covered by the BS for the whole transmission time. Performance evaluation results show that the proposed scheme outperforms the conventional three-sector transmission by 171% in low 5% UEs in terms of the UE throughput.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.4 s.107
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• pp.358-367
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• 2006

In this paper, a mathematical formulation of protection ratio and its calculation method are suggested for a radio relay system with diversity techniques. The analysis of protection ratio and its physical meaning have been performed for the space or frequency diversity system, and in particular protection ratios are reviewed in terms of the parameters of diversity improvement factor, which comprises antenna gain, separation distance between antennas, frequency and its difference between carriers, and distance. As one of simulated results, the co-channel protection ratio of 60 dB is obtained for the space diversity system regarding 6.2 GHz, 60 km, 64-QAM, and 25 m between antennas, which gives 15 dB less than the co-channel protection ratio of the non-space diversity system. In addition, the co-channel protection ratio for the frequency diversity system gives 64 dB in case of frequency offset of 0.5 GHz under the same conditions as the space diversity system, which brings about 11 dB less than the co-channel protection ratio of non-frequency diversity system. In consequency, it is interesting to note that the space diversity system is less sensitive to interference in comparison to the frequency diversity system and provides better quality of service for a given interference.

• Journal of Navigation and Port Research
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• v.40 no.1
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• pp.43-50
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• 2016

Amid of the logistics hub center competition is going to intensifying between the world major port, it is essential to pre-occupied the base in the logistics hub world take advantage of advanced technology of logistics equipment than other ports. In existing container terminal, when container moves the terminal use the omnidirectional and directional antenna in order to exchange data information on the basis of 802.11 wireless network system. Case of loading height of exceeding, the blind sport will occur and a limited frequency channel can't help using in the area. A limited frequency channel usage and nested areas happen to use the closed terminal, it has a great influence to operate the terminal working. In this paper, LTE network is configured provided by the specified company ('L' Corp,.Ltd) and terminal data extracted through LBO (Local Breakout) in the cell site which is configured directly with container terminal operation server. Using this method, container terminal yard equipment operate without overlapping arises with uninterrupted data presented for ways to efficiently. I would suggest both the existing wireless AP LAN configuration of container terminal and new LTE system and applied to the real yard operating devices situations. Through these methods presented comparative the existing network traffic with new constructed LTE configuration. I admired to suggest that wireless network LTE introduction is fundamental factors to get rid of the blind spot, the problem of limited frequency channel and overlapping arises. These essential points can be a continual improving terminal services and more efficient terminal operational management.

• Journal of Navigation and Port Research
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• v.41 no.4
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• pp.189-194
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• 2017

The Moving Search Radar System (MSRS) monitors sea areas by moving along the coast. Since the radar is initially aligned to the front of the vehicle, it is important to know the changes in the heading azimuth of the vehicle to quickly acquire the target azimuth from the radar after the MSRS has moved. The heading azimuth can be obtained using the gyro compass, the GPS compass or the electronic compass. The electronic compass is suitable for MSRS requiring fast maneuverability due to its small volume, short stabilization time and low price. However, using a geomagnetic sensor may result in an error due to the surrounding magnetic field. Errors can make early automatic tracking of the satellites difficult and can reduce the radar detection accuracy. Therefore, this paper proposes a method to automatically compensate for the error reflecting the correction value on the radar obtained by comparing the reference azimuth calculated by solving the geodesic inverse problem using two coordinates between the radar and the geostationary satellite with the actually-directed azimuth angle of the satellite antenna. The feasibility and convenience of the proposed method were verified by applying it to the MSRS in the field.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5B
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• pp.385-394
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• 2012

The tactical mobile communication network, which comprises a part of the next-generation Tactical Information and Communication Network (TICN), provides means of communication and control for Tactical Multi-Functional Terminals (TMFT) belonging to a Mobile Subscriber Access Point (MSAP). The next-generation of MSAP is capable of constructing a backbone network via LCTR and HCTR directional antennas. At the same time, WMN modules are used to create and manage a wireless mesh backbone. When directional antennas are used in mobile environments, seamless services cannot be efficiently supported as the movement of the node prevents the angle of the antenna to constantly match. Therefore, data communication through the wireless mesh networks is required to provide direct communication between mobile MSAPs. Accordingly, mutual authentication and data encryption mechanisms are required to provide reliable data transmission in this environment. To provide efficient mutual authentication between MSAP devices, the process of verifying a certificate of the other MSAP device through its own authentication server is required. This paper proposes mutual authentication mechanisms where the MSAP requiring authentication and the MSAP that permits it initiates low-cost and efficient authentication in a distributed way. More specifically, we propose a method of applying EAP-ELS (Extensible Authentication Protocol-Transport Layer Security) in the next-generation TICN.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.7 s.361
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• pp.9-15
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• 2007

In this paper, we present the design of Schottky diodes and voltage multiplier for UHF-band passive RFID applications. The Schottky diodes were fabricated using Titanium (Ti/Al/Ta/Al)-Silicon (n-type) junction in $0.35\;{\mu}m$ CMOS process. The Schottky diode having $4{\times}10{\times}10\;{\mu}m^{2}$ contact area showed a turn-on voltage of about 150 mV for the forward diode current of $20\;{\mu}A$. The breakdown voltage is about -9 V, which provides sufficient peak inverse voltage necessary for the voltage multiplier in the RFID tag chip. The effect of the size of Schottky diode on the turn-on voltage and the input impedance at 900 MHz was investigated using small-signal equivalent model. Also, the effect or qualify factor of the diode on the input voltage to the tag chip is examined, which indicates that high qualify factor Schottky diode is desirable to minimize loss. The fabricated voltage multiplier resulted in a output voltage of more than 1.3 V for the input RF signal of 200mV, which is suitable for long-range RFID applications.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.7
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• pp.26-36
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• 2014

The needs of active phased arrays antenna system is getting more increased for IMT-Advanced system efficiency. The active phased array structure consists of lots of small transceivers and radiation elements to increase system efficiency. The minimized module of high efficiency transceiver is key for system implementation. The power amplifier of transmitter decides efficiency of base-station. In this paper, we design and implement minimized module of high efficiency transceiver for IMT-Advanced active phased array system. The temperature compensation circuit of transceiver reduces gain error and the analog pre-distorter of linearizer reduces implemented size. For minimal size and high efficiency, the implented power amplifier consist of GaN MMIC Doherty structure. The size of implemented module is $40mm{\times}90mm{\times}50mm$ and output power is 47.65 dBm at LTE band 7. The efficiency of power amplifier is 40.7% efficiency and ACLR compensation of linearizer is above 12dB at operating power level, 37dBm. The noise figure of transceiver is under 1.28 dB and amplitude error and phase error on 6 bit control is 0.38 dB and 2.77 degree respectively.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.4
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• pp.17-24
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• 2009

This paper deals with the cancellation performance of loop back interference signal in the case of multihop relay of 16-QAM received signal at the USN radio network. For this, it is necessary to the exchange of information with long distance located station by means of the relay function between the node in the USN environment. In the relay node, the loop-back interference signal which the retransmitting signal is feedback to the receiver side due to the antenna of transmitter and receiver are co-used or very colsely located or using the nonlinear device. Due to this signal, the performance of USN system are degraded which are using the limited resource of frequency and power. For improve this, it is necessary to applying the adaptive signal processing algorithm in order to cancellating the unwanted loop-back interference signal at the frontend of receiver in relaying node, we can get the better system and multi hop performance. In the adaptive signal processing, we considered the 16-QAM signal which has a good spectral efficiency, firstly, than, the QR-Array RLS algorithm was used that has a fairly good convergence property and the solving the finite length problem in the H/W implementation. Finaly, we confirmed that the good elimination performanc was confirmed by computer simulation in the learing cuved and received signal constellation compared to the conventional RLS.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.3
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• pp.389-398
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• 2011

In this paper, the design and fabrication of a transmit/receive(T/R) module for Ka-band phased array radar is presented. A 5bit digital phase shifter and digital attenuator were used in common for both transmitter and receiver considering unique Ka-band characteristic. The circulator was excluded in the T/R module and was placed outside T/R module. The transmitting power per element antenna is designed to be about 1 W and the noise figure is designed to be below 8 dB. The designed T/R module RF part has a compact size of $5\;mm{\times}4\;mm{\times}57\;mm$. In order to implement the T/R module, MMICs used in T/R module was separately assessed before assembly of the designed T/R module. The transmitter of the fabricated T/R module shows about 1 W at 5 dBm unit module input power and the receiver shows a gain of about 20 dB and a noise figure of below 8 dB as expected in the design stage.