• 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.

• Journal of Advanced Navigation Technology
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• v.26 no.6
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• pp.481-486
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• 2022

The recent rapid growth of the IoT(Internet of Things) is leading to the spread of low-power wireless technology. A major challenge in designing IoT wireless networks is to achieve coexistence between different wireless technologies that share the 2.4 [GHz] ISM (Industrial Scientific Medical) frequency band. Therefore, there is a need for research on improving the reliability of wireless networks and coexisting operation between wireless networks. In particular, it is necessary to study an interference model and performance for mutual service coexistence in a BLE (Bluetooth Low Energy) wireless network environment, which is expected to be widely used as a connection medium between devices in various industrial fields. In this paper, the co-channel interference model with the IEEE 802.15.4 system is established focusing on the physical layer of the BLE system widely used in residential and industrial wireless applications, and the performance of the BLE wireless communication system is analyzed in the co-channel interference environment. As a result of the analysis, as the distance between the interference source and the BLE system increases in an environment where noise and co-channel interference exist, the amount of co-channel interference decreases and the error rate performance of the BLE system improves.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.2
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• pp.230-238
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• 2022

Internet of Things(IoT) is a communication technology that collects information of object remotely and controls the function of object by adding a communication function to object that does not have a communication function. For the IoT, various communication technologies such as Wi-Fi, 3GPP, and Bluetooth are available, and Long Range(LoRa) is communication technologies specialized in the IoT concept. LoRa is a communication technology that support long-distance, low-power, and low-speed communication, and is suitable for collecting information generated form object in remote equipment and controlling equipment. Because of these characteristics, it is used in many application field, and various performance improvement studies are in progress. This paper intends to propose an ultra-long-range LoRa communication module that can be used in a wider range of applications. We design and implement hardware, firmware, and application software for testing to develop ultra-long-range LoRa communication modules. The implemented module will be tested in a real environment to verify its performance and to check its utilization.

• KIPS Transactions on Computer and Communication Systems
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• v.13 no.1
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• pp.21-30
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• 2024

As the self-driving car market continues to grow, the need for charging infrastructure is growing. However, in the case of a wireless charging system, stability issues are being raised because it requires a large amount of power compared with conventional wired charging. SAE J2954 is a standard for building autonomous vehicle wireless charging infrastructure, and the standard defines a communication method between a vehicle and a power transmission system. SAE J2954 recommends using physical media such as Wi-Fi, Bluetooth, and UWB as a wireless charging communication method for autonomous vehicles to enable communication between the vehicle and the charging pad. In particular, UWB is a suitable solution for indoor and outdoor charging environments because it exhibits robust communication capabilities in indoor environments and is not sensitive to interference. In this standard, the process for building a wireless power transmission system is divided into several stages from the start to the completion of charging. In this study, UWB technology is used as a means of fine alignment, a process in the wireless power transmission system. To determine the applicability to an actual autonomous vehicle wireless power transmission system, experiments were conducted based on distance, and the distance information was collected from UWB. To improve the accuracy of the distance data obtained from UWB, we propose a Single Model and Multi Model that apply machine learning and deep learning techniques to the collected data through a three-step preprocessing process.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1211-1213
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• 2002

We have frequently felt it inconvenient to collect fare drawing the card in transportation system. Especially, for subway the fares of mass transportation at rush hours of the days, it's important to find a way to collect fares without unnecessarily delaying passengers. In this paper, we proposed a system for the gateless fare collection passing through the booth in only carrying the card. In this system that RF-ID system and Bluetooth are applied. We designed two wireless communication channels. One is the 125kHz communication channel by FSK and PSK for power supplying on the card and identification and the other is 2.4GHz channel for the collection.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.652-659
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• 2011

Due to overuse of commercial network systems such as bluetooth and WI-FI, the problems of frequency interruption and line-crossing may arise. For this reason, wireless communication frequency ISM 2.4GHz, a recently adapted concept in Korea which is employeed by RF-CBTC system, is predicted not to have guarantee for outstanding and continuous performance. Therefore in this study, considering these problems, 5GHz capacity wireless Lans with international standard 802.11a/b/g applied were installed in the underground urban transit areas and it was proved that these lans exceeded the performance level of 2.4GHz with international standard 802.11b which is being introduced in the nation. In addition, it was verified through carrying out an application test that the communication condition was stable in a running train with high speed in the tunnel.

• Journal of Digital Contents Society
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• v.11 no.2
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• pp.277-282
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• 2010

In this paper, the wireless transmission module is developed to transmit oxygen saturation(SpO2) signal, acquired from bio-signal measuring module, to PC. This wireless transmission module is designed with closed type protocol instead of open type protocol such as a zigbee or a bluetooth, considering of the security of personal medical informations. The display software is also developed to display transmitted SpO2 signals by various type data and graph without information loss for a emergency transfer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.752-755
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• 2004

선박용 엔진의 제작에 있어 크랭크 샤프트 조립 시 1 회전의 상태에서 크랭크 스루 간의 디플렉션의 상대값이 정상오차 범위를 넘어서는지 확인한 후 조립상태를 보정하게 된다. 기존의 방법은 다이얼 게이지를 사용하여 측정 담당자가 베드 플레이트 내에 들어가 크랭크 샤프트 회전 시 따라 돌면서 직접 육안 확인을 통해 측정이 이루어졌다. 이 때, 측정의 불편함과 열악한 작업환경 하의 안전 문제가 야기된다. 이러한 문제점을 해결하기 위해 본 연구에서는 블루투스 통신을 이용하여 디지털 게이지를 사용한 측정장치 기구부의 신호를 무선으로 받아서 작업자는 베드 플레이트 외부에서 측정이 가능하도록 하는 시스템의 개발하였다. 이를 통해 작업의 편리성 및 안정성을 확보했으며, 디지털 측정을 통한 측정의 정확도를 향상시켰다.

• Proceedings of the Korea Contents Association Conference
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• 2011.05a
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• pp.521-522
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• 2011

본 논문에서는 특정 위치를 비행하는 무인항공기를 이용하여 현재 위치의 수집된 센서 정보, GPS 수신정보, 영상정보를 무선통신을 이용하여 전송하는 정보 전송시스템을 구현한다. 무인항공기에 부착된 센서, GPS수신기, 소형카메라를 통해 산불 및 자연재해를 감지하고, 무선통신을 이용하여 감지된 위치의 정보들을 사용자에게 전송한다. 제안된 시스템은 위험 지역에 사람이 직접 가지 않고도 실시간 위험 상황을 파악 및 신속한 대처가 가능하다.

• Journal of information and communication convergence engineering
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• v.6 no.3
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• pp.249-254
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• 2008

Moored ocean buoys are technically feasible approach for making sustained time series observation in the oceans and will be an important component of any long-term ocean observing system. The 3M disc buoy carried Zeno 3200, MCCB, Orbcomm, Global Star and Bluetooth module. The deployments have relied on Orbcomm and Global Star as the primary satellite communications system. In addition to detailing our practical experience in the use of Orbcomm and Global Star as high latitudes, we will present some of scientific sensor results regarding real-time oceanographic and meteorological parameters such as wind speed, wave height and etc. In this paper we present the design and implementation of a small-scale buoy sensor network. One of the major challenges is that the network is hard to access after its deployment and hence both hardware and software must be robust and reliable.