• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.1
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• pp.42-49
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• 2003

OFDM should be used for the fourth generation communication for high speed communication. Because of high spectral efficiency and high tolerance to fading channel, OFDM is applied to many high speed wire and wireless communication such as DAB (Digital Audio Broadcast), DVB(Digital Video Broadcast), IMT 2000 etc. Inter-modulation, however, is derived from PAR(Peak to Average Power Ratio) of OFDM signals. The paper describes PTS(Partial Transmit Sequence) and SLM(Select Mapping) of an existing methods which can reduce PAR. And then this papers proposed the new method that is called "Combine method". The method proposed in this paper is to combine PTS and SLM. As a result of the simulation, Combine PAR method is better than the existing methods.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.1
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• pp.58-63
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• 2011

This paper presents a development of a fire control system with an intelligent judgment algorithm of hit or not. The presented algorithm analyzes an impact energy and impact signals according to impact materials. And the detected signals are used to judge the correct hit or not. Furthermore, Zigbee wireless communication technology is applied in the developed fire control system. The wireless communication technology can supply a simple installation of the practical system and free from ageing of communication wire. The presented system is verified in the practical fire test, and the results show the effectiveness of the development system.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.1
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• pp.8-13
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• 2022

This paper investigates the method to implement a RF (Radio Frequency) energy harvesting sensor node and to build a sensor network using a CATV network and a leaky coaxial cable. The power supply of a sensor node is designed with the WPTS (Wireless Power Transfer System) receiver operating at 915MHz. A sensor network has limited coverage by the loss of RF signal at a wireless transmission link. The paper proposes to build a sensor network that the BLE signal of a sensor and the signal of a WPTS power transmitter are transmitted through a coaxial cable of a CATV network by utilizing WOC (WiFi over Coax) technology and radiates at a leaky coaxial cable. The length of a leaky coaxial cable and the total loss of a wire link are allowed to the point that the RSSI of a sensor node is more than the minimum value (-78dBm) and lead to extend wireless coverage.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.6
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• pp.886-890
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• 2013

Uplift of contact wire and dynamic characteristics between pantograph and contact wire are key interaction performance of OCS (Overhead Catenary System). These two evaluation items are the approval criteria for the performance between OCS and pantograph. A telemetry system or DAQ (Data Acquisition) System based on wireless communication make it monitor a dynamic behavior which is measured directly in a 25 kv like parts. While permissible working time is too short time to install is too long. In this paper, it is described that optimization the telemetry measurement system for OCS and increasing accuracy, easy adaptation, and faster handling can be also achieved through the study.

• Fire Science and Engineering
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• v.31 no.5
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• pp.117-122
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• 2017

The absence of fire fighters' connection to communication can bring about increased loss of life due to errors and delays in rescue and actions and danger to their own safety. Therefore, when communication infrastructure has been destroyed in an enclosed space, it is necessary to set up an emergency wire or wireless telecommunication environment to fire fighting and to secure safer environment to deal with the disaster by checking the location of fire fighters. In this research, for the establishment communication environment in an enclosed inside using Ultra-Wide Band (UWB) wireless communication network, the performance of communication position determination of a single UWB communication module was evaluated regarding 6 kinds of indoor surroundings. When the communication distance in an indoor environment of each 6 channels bandwidth of UWB communication frequency was measured, the results were as follows: the open space (Ave. 15.5 m, Max. 20 m), the corridor (Ave. 17.33 m, Max 20 m), inside retaining home furnishings (Ave. 15.3 m, Max. 20 m), vertical stairs (Ave. 4.33 m, Max. 6 m), horizontal space with a closed fire door (Ave. 6.5 m, Max. 17 m). It was also found out that the communication function and the distance function were best in the frequency range from 6489.6 to 1081.6 MHz by 7 Ch. Accordingly, the establishment of communication environment in an enclosed space is judged to be possible when UWB communication module is set up at 20 m apart and multiple channels are used.

• The KIPS Transactions:PartC
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• v.9C no.2
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• pp.197-212
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• 2002

Transmission Control Protocol (TCP) [1] has been tuned as a reliable transfer protocol for traditional networks comprising wired links and stationary hosts with same link characteristics. TCP assumes that congestion in the network be a primary cause for packet losses and unusual delays. TCP performs welt over such networks adapting to end-to-end delays and congestion losses, by standard congestion control mechanisms, such as slow-start, congestion avoidance, fast retransmit and recovery. However, networks with wireless and other lossy links suffer from significant losses due to bit errors and handoffs. An asymmetry network such as ADSL has different bandwidth for both directions. As a result, TCP's standard mechanisms incur end-to-end performance degradation in various links. In this paper, we analyze the TCP problems in wireless, satellite, and asymmetry links, and measure the new TCP mechanisms that are recommended by IETF Performance Implications of Link Characteristics (PILC) WG[2], by using Network Simulator 2 (NS-2).

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.89-94
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• 2015

FMS which has a concept that wireless terminal can replace wire terminal services is a technologies that is can provide service costs same as wire terminal in the special zone. Enterprise type of FMC that is developed making up for the weak point is must have to improve voice quality and FMC performance in the soft phone. This paper measure voice quality based on the one way of the total estimated delay time of FMC to carry out IMS services between IP-PBX and FMC soft-phone to operate it's controller optimally and put forward evidence to be in 120ms and 150ms in the VoIP FMC voice quality. To measure FMC performances in four categories evaluated trials and prove its performances.

• Korean Journal of Audiology
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• v.18 no.3
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• pp.105-111
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• 2014

Assistive listening devices (ALDs) refer to various types of amplification equipment designed to improve the communication of individuals with hard of hearing to enhance the accessibility to speech signal when individual hearing instruments are not sufficient. There are many types of ALDs to overcome a triangle of speech to noise ratio (SNR) problems, noise, distance, and reverberation. ALDs vary in their internal electronic mechanisms ranging from simple hard-wire microphone-amplifier units to more sophisticated broadcasting systems. They usually use microphones to capture an audio source and broadcast it wirelessly over a frequency modulation (FM), infra-red, induction loop, or other transmission techniques. The seven types of ALDs are introduced including hardwire devices, FM sound system, infra-red sound system, induction loop system, telephone listening devices, television, and alert/alarm system. Further development of digital wireless technology in hearing instruments will make possible direct communication with ALDs without any accessories in the near future. There are two technology solutions for digital wireless hearing instruments improving SNR and convenience. One is near-field magnetic induction combined with Bluetooth radio frequency (RF) transmission or proprietary RF transmission and the other is proprietary RF transmission alone. Recently launched digital wireless hearing aid applying this new technology can communicate from the hearing instrument to personal computer, phones, Wi-Fi, alert systems, and ALDs via iPhone, iPad, and iPod. However, it comes with its own iOS application offering a range of features but there is no option for Android users as of this moment.

• KEPCO Journal on Electric Power and Energy
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• v.3 no.1
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• pp.1-7
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• 2017

The collection and analysis of power information in the smart grid is essential. The collected utilize power information can be used to efficiently utilize power such as power generation and distribution. The role of smart meters communication through wire and wireless cable is important for collecting power information. Recently, many countries around the world are establishing international standards or unique standards of smart meter communication for power information collection of many smart meters. Thus, this paper investigates smart meter related papers and materials, and summarizes international and national standards for smart meter communication.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.1568-1571
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• 2011

본 논문에서는 구현한 것은 워드프로세서 자격검정 모의고사를 유선 인터넷을 통하여 테스트 해볼 수 있는 프로그램이다. 워드프로세서 시험 등급은 1급으로 구성되어 있으며, 유선으로 이용 가능한 서비스를 좀 더 확대하여 모바일 기기로도 접속하여 응시내역을 확인할 수 있도록 제작되었다. 또한 모의고사 응시 후 과목별 오답노트를 제공하여, 틀린 문제를 모의고사 후에 재복습도 가능하도록 설계 및 구현하였고, 다른 응시생과 시험 결과를 비교할 수 있도록 하여 자신의 현재 성적 중에서 부족한 부분을 확인한 후 추가 학습을 통해 채울 수 있도록 하였다. 모바일 기기를 통해 유선 인터넷에서 응시한 모의고사의 응시내역을 확인할 수 있도록 구현한 것은 시간 및 공간의 제약없이 확인하는 방법을 제공하기 위함이다.