• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.6
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• pp.55-62
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• 2008

An Estimation of VHF datalink range for EW(Electronic Warfare) equipment in the sea environment was studied to predict the datalink range between transmitting and receiving station. We consider refraction and reflection in addition to the basic radar equation. The reflection especially includes propagation factor in case of spherical earth as well as flat earth. The estimation result can predict the real datalink range within 5% error.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.3
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• pp.413-420
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• 2010

An Estimation of VHF data link range for EW(Electronic Warfare) equipment in the sea environment was studied to predict the data link range between transmitting and receiving station. The theoretical estimation predicts within 3% error with actual measurement of VHF data link range at sea. Data link range factors including refraction and reflection are added in the basic wave propagation equation. The effect of refraction and reflection to the range is analysed with quantity level.

• Defense and Technology
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• no.4 s.254
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• pp.54-65
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• 2000

셀룰라망을 이용한 위치보고체계는 전파통달거리를 고려한 셀 단위로 구축하였기 때문에 지휘망을 이용하는 방안에 비해 신뢰성 있는 보고를 기대할 수 있으며, 동일한 정보를 1, 2차 상급부대에 중복 보고할 필요가 없고, 일정거리 이상의 다른 셀에서 같은 대역의 주파수를 사용해도 무방하므로 주파수 재사용의 효과도 거둘 수 있다. 아울러 인터넷과 데이터 베이스 관리 시스템을 소프트웨어로 효과적으로 연동시킴으로써 현재 상용에서 각광 받고 있는 Web-Server 개념을 군 무선 데이터 통신에 도입하고 하드웨어도 대용량의 지능망으로 발전한다면 위치보고 뿐만 아니라 늘어나는 정보를 효과적으로 처리하기에 충분하리라 판단된다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1876-1883
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• 2016

The new channel model for high data rate common data link(CDL) is proposed. The Two-ray channel, which is composed of the reflected signals on the front ground of the receiver, is considered in this paper. This channel arises due to the curvature of the earth when the altitude of the transmitter is tens of kilometers and distance between the transmitter and the receiver is hundreds of kilometers. The Two-ray channel is modeled by estimating the maximum delay profile and the power delay profile, depending on the transmitting and receiving beamforming angle and the radiation pattern of antenna. The power delay profile has a larger effect on the bit error rate(BER) over signal to noise ratio(SNR) than the maximum delay profile, because the distance range is too long in the proposed channel model.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.3
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• pp.109-115
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• 2009

Recently, the relay communication is focused for the power saving and coverage extension of ad-hoc networks. For the high date rate transmission, it is proposed to adapt OFDMA relays. In this paper, we assume the 2 hop cooperative OFDMA relays between the source and the destination. The performance of 3 different relaying methods are derived and compared. We noticed that the selective OFDMA relaying method has the best performance followed by opportunistic OFDMA relaying and repetition-based OFDMA relaying method under the same threshold mutual information rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.10
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• pp.965-976
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• 2012

Multi-Platform Image and Intelligence Common data link(MPI-CDL) systems are designed to transmit the imaginary and signal intelligence data at an aeronautical to ground line of sight(LOS) link. This paper proposes a method to predict a link availability and analyzes the required link margin to satisfy a given link availability for MPI-CDL systems. To estimate a link availability the proposed method applies the conditional probability so that both a rain attenuation and a multipath fading are considered simultaneously. Link margins to meet the link availability for MPI-CDL systems are calculated according to an operating environment including frequencies, flight altitudes and transmission ranges. The required link margins for actual unmanned air vehicle systems are also given by simulation results.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.4
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• pp.157-166
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• 2022

The most commonly used wireless communication technologies in IoT technology include ZigBee, WiFi, Bluetooth, and Z-Wave. In particular, Z-Wave is currently one of the preferred wireless communication technologies, with a global market share of 60 % of these technologies. In this research, a temperature and humidity sensor module using a Z-wave protocol was designed and manufactured by referring to the data sheet. Subsequently, the Z-Wave protocol was analyzed during the operation of the sensor module, and the firmware of the controller module was mounted and implemented. In addition, a program for monitoring the temperature and humidity information from the sensor module was developed and validated. Finally, the performance of the sensor module was validated through master distance and low power tests on it and its reception data success rate.

• Journal of Digital Convergence
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• v.14 no.11
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• pp.325-331
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• 2016

The purpose of this study is to analyze the effect of the glass ceiling induction factors on the improvement of the job Commitment on the glass ceiling perception and to analyze the effect of the organizational Commitment on the influence of the local medical institute and private medical institute employees. As a research method, structural equation model analysis was carried out to investigate the influence relationship of each factor. In particular, multiple group analysis was performed to analyze the difference of influence relations between public and private medical personnel, respectively. Result: First, empirical studies on the effect of the glass ceiling inducing factors on job Commitment showed that job Commitment was influenced by stereotype and organizational culture, and the magnitude of the influence was different. Second, the employees of the room medical center were influenced by perceived promotion, job placement, education and training, reward, and job satisfaction. Third, in the hypothesis that job Commitment will be affected by the perception of glass ceiling, only the workers of the private medical center showed significant results. Based on the results of this study, it will be necessary to plan policies to improve the perception of the glass ceiling phenomenon and improve its status in order to improve the personnel and system with which women workers in the medical field can enter more senior management positions.

• Journal of Korea Society of Industrial Information Systems
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• v.23 no.6
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• pp.59-66
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• 2018

In this paper, we experimented how long distance voice communication is possible After implemented PTT(Push to talk) Bi-directional radio using open source project Codec 2, which is a low speed voice codec for digital amateur radio and 900MHz FSK transceiver. In case of a general digital radio, the AMBE+2 codec, which is regarded as an industry standard in terms of performance, is expensive and has the monopoly of technology. Using the 400MHz band in terms of frequency, narrow bandwidth of DMR(12.5kHz) and DPMR(6.25kHz) is used, so the data rate is low. In the 900MHz bandwidth can be extended, which is advantageous in terms of data transmission. As a result of the voice quality and distance field test, we could find that the communication takes place within about 500m. In this paper, only voice communication is reviewed. if a review of data transmission such as a simple image is added, this solution can be used in various fields as a low cost IOT radio.

• Journal of Advanced Navigation Technology
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• v.13 no.6
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• pp.916-925
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• 2009

4S (Ship to Ship, Ship to Shore) communication is the key to strategic development of e-navigation, a core element of IT vessel convergence. 4S communication is intended to integrate and standardize various communication infrastructures on land and communication equipment complying with communication equipment equipped in ships. This paper aims to apply the Korean technology IEEE 802.16e adopted as an international standard, to replace and compensate for existing vessel communication media such as low speed HF/MF/VHF to the ocean environment. To this end, various experimental conditions between the coast station where a relay station was installed and related equipment equipped on a ship are set. Communication signals were monitored and the RSSI and CINR were measured. Based on experimental analysis and results, various challenges and solutions which may occur in ocean environment were sought, and communication availability was analyzed through transmission data throughput, at the maximum effective distance range of the signal. It was proven that high speed multimedia data could be exchanged for up to 20 km even among 80km kph ships moving around near the sea, ensuring that this technology could be applied to the ocean environment.