• Journal of Navigation and Port Research
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• v.31 no.10
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• pp.865-868
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• 2007

Recently, wireless LANs are often applied in home or office because of its various of convenience. Frequency range of wireless LANs specified by IEEE 802.11b is at 2.4 GHz. The bluetooth, the microwave oven, and the PDA(Personal Digital Assistants) uses, however, the same frequency band. So problems will be produced in these environments, such as multi-pass interference and system-to-system interference. These problems can be eliminated by using EM wave absorber. In this paper, we designed and fabricated EM wave absorber using MnZn-Ferrite, Sendust, and CPE( Chlorinated Polyethylene). The EM wave absorber with the ratio of material (MnZn-Ferrite : Sendust : CPE = 64 : 16 : 20 wt.%) has thickness of 3.7 mm and absorption ability more than 17 dB at 2.4 GHz.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.5
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• pp.1103-1108
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• 2010

In this paper, Frequency Synthesizer which is widely used for FH-SS system is proposed and the experimental results are analyzed. The performance of the DPLL(Digital Phase-Locked-Loop), which is the main part of the Synthesizer is analyzed by the computer program. Using Maxplus-II tool provided by altera. co., ltd, each part of the DPLL is designed and all of them is integrated into EPM7064SLC44-10 chip. And the simulation results are compared with the characteristics of the implemented circuits for analysis. And the experiential results show that the N value of the loop filter is toggled to adjacent N value, which result in phase jitter of the output. It can be resolved by increasing DCO(Digital Controlled oscillator) clock rate.

• Journal of Practical Engineering Education
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• v.8 no.1
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• pp.1-7
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• 2016

In this paper, the proceedings and core procedures that involved the role of advisor to the theme, the set up rule of students, and complete the work steps involved in configuring graduate work that the overall design curriculum and graduation standards are summarized. The one or two students are designated as one team, and by the designated professor was conducted a discussion and technical guidance. Among various topics from 2011 to 2015, some specific results configured using a small drone and smartphones are presented. The survey are compared the activity results for the participating students in one major each in 2011 and 2015 and analyzed. Based on this review for improvement next year notes, it forms a continuous improvement, and has converged talents with passion and challenging spirit, sharing a plan to form a virtuous cycle that is associated with positive employment and entrepreneurship.

• Journal of Sensor Science and Technology
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• v.20 no.4
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• pp.272-278
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• 2011

Recently, the performance of binaural hearing aids is rapidly improved with the technology advancement of wireless communication, digital signal processing, and integrated circuit design. However, the previous hearing aids developer platforms can't be applied to binaural hearing aids developing, because it has no consideration for wireless communication and binaural hearing control. Also, the previous developer platforms are not easy to use for the algorithm development, because programming languages are limited. In this paper, we designed and implemented the open platform board for binaural hearing aids developing. The designed board can be programmed by general programming language and can be used wireless communication module. In order to verify the designed open platform board, we used the volume control algorithm using two open platform board. As a result of experiment, we verified the performance of designed and implemented open platform board that was successfully operated the binaural hearing control and the wireless communication.

• Smart Media Journal
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• v.4 no.3
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• pp.38-43
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• 2015

The increased number of smart devices leads users to share multimedia contents with others. Smart device users transmit multimedia files using apps. For multimedia file transfer under NAT (Network Address Translator), a lot of apps exploit a server with public IP or short range communication technologies such as WiFi Direct or Bluetooth because smart devices with private IP address cannot communicate each other directly. We first proposed the push service based file transmission scheme without an additional server and distance limitation. Second, for the push service based transmission, we proposed congestion control scheme to adapt transmission rate to the receiver's link bandwidth. Third, we considered bandwidth aware transmission for senders with different bandwidth. We implemented apps to evaluate the proposed scheme, and conducted experiments with smart devices.

• Smart Media Journal
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• v.8 no.4
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• pp.9-16
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• 2019

In order to realize IoT(Internet of Things) service, it is necessary to manage sensing data and build a service with respect to its scalability. However, existing internet services use unique protocols and non-standardized functions for each service provider, and it is difficult to provide data management and service because they use short-range communication technology such as Bluetooth. In addition, plurality of APs and gateways must be taken into consideration in establishing a wide area network. In this paper, we propose a sensing data management system using LoRa(Long Range) communication based on Mobius platform. The end device that drives Tas is configured to collect sensing data, configure an application gateway that drives &Cube, and transmit sensing data to the server. In addition, a server that manages the Mobius is configured to handle the sensing data transmitted from the application gateway to provide a monitoring service. We establish a wide area network through LoRa communication between the end device and the gateway and provide data management and service corresponding to the internet through the Mobius platform.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.2
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• pp.431-438
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• 2017

In this paper, the abdomen ECG(AECG) is employed to measure the mother's ECG instead of the conventioanl thoracic ECG measurement. The fetus ECG signal can be extracted from the AECG using an algorithm that utilizes the mobile fetal ECG measurement platform, which is based on the BLE (Bluetooth Low Energy). The algorithm has been implemented by using a replacement processor processed directly from the platform BLE instead of the large statistical data processing required in the ICA(Independent component analysis). The proposed algorithm can be implemented on a mobile BLE wireless ECG system hardware platform to process the maternal ECG. Wireless technology can realize a compact, low-power radio system for short distance communication and the IOT(Intenet of Things) enables the transmission of real-time ECG data. It was also implemented in the form of a compact module in order for mothers to be able to download and store the collected ECG data without having to interrupt or move the logger, and later link the module to a computer for downloading and analyzing the data. A mobile ECG measurement prototype is manufactured and tested to measure the FECG for pregnant women. The experimental results verify a real-time FECG extraction capability for the proposed system. In this paper, we propose an ECG measurement system that shows approximately 91.65% similarity to the MIT database and the conventional algorithm and SNR performance about 10% better.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.1 no.2
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• pp.99-105
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• 2008

Entering the twenty-first century, the technology of wireless communication develops the applications with the ubiquitous concept. It is standardized and can be choose for various uses in different fields. With this trend and the advantages of wireless system, the research is conducted to use wireless system instead of wire system to existing equipment on aircraft. Wireless system is general on aircraft. However, wire system is used to communicate ground crew and pilot and to get data from equipment installed on aircraft. In this study, a wireless voice communication system was developed to communicate ground crew and pilot on aircraft as effective wireless system. Also, a wireless system to transmit and receive voltage and current data was developed.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.6
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• pp.535-544
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• 2017

In this paper, to overcome the limitation of information transmission and reception according to the RF system of UAV, it is necessary to check the position of many UAVs in flight on the basis of mobile communication and to make the LTE modem lightweight and low power And UAVs that are in operation are received and controlled. Through this study, we proposed a method to control real-time location tracking by connecting high-resolution images to the network anytime and anywhere. For this purpose, we propose the requirements and requirements of LTE modem using real-time high-speed data communication technology (3G, 4G LTE, Bluetooth) by presenting the communication module system of LTE-based UAV. N:N control system concept and implementation technology(Control system structure, control data flow chart, flight planning and transmission, real-time location tracking).

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.5
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• pp.1211-1221
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• 2016

In IoT environment, making sure of trust of IoT devices is the most important one than others. The security threats of nowadays almost stay at exposure or tampering of information. However, if human life is strongly connected to the Internet by IoT devices, the security threats will probably target human directly. In case of devices, authentication is verified using the device-known private key. However, if attacker can modify the device physically, knowing the private key cannot be the evidence of trust any more. Thus, we need stronger verification method like code attestation. In this paper, we use software-based code attestation for efficiency. We also suggest secure code attestation method against copy of original code and implement it on embedded device and analyze its performance.