• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.261-264
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• 2006

지능형 차량정보 시스템은 21세기 교통체계로 기대를 모으고 있는 ITS(Intellligent Transport System)의 구축에 핵심이 되는 시스템이다. 이러한 시스템을 구현하기 위해서 종래의 네비게이션, 차량용 무선통신, 차량진단 등의 단일화된 시스템을 통합적으로 수행하며, 계측 또는 수집된 데이터를 분석하여 지능적으로 차량의 주행 상태를 분석 / 진단함으로써 차량에서의 안전한 운행과 운전자 및 승객들이 요구하는 정보 또는 다양한 서비스를 제공하기 위한 새로운 모듈의 개발이 절실히 필요한 실정이다. 따라서, 본 논문에서는 CAN(Controller Area Network) BUS을 이용한 차량의 상태수집 모듈과 능동 데이터베이스에 관해 기술하고 이를 통합하기 위한 임베디드 보드를 이용한 CAN BUS연계형 차량용 복합통신모듈의 프로토타입 H/W을 구성하여 실용화 가능성 및 유용성을 제시하고자 하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.872-875
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• 2005

Portable Internet extended from wireless LAN has a large cell size, similar to a wireless mobile communication, and can provides the seamless service which offers middle-low speed mobility. IEEE 802.16e, the international standard of Portable Internet, uses PKMv2(Privacy Key Management) protocol for authorization and key exchange between a MSS(Mobile Subscriber Station) and a BS(Base Station). This paper first reviews and studies overall security architecture of TTA HPi standard and IEEE 802.16e which supports mobility based on WMAN(Wireless Metropolitan Area Network) standard(IEEE 802.16)

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.538-541
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• 2009

Increasing of number of people who suffered from long term chronic diseases which required frequent daily health monitoring and body check up in conjunction with the trendy uses of mobile phones and Personal Digital Assistants (PDAs) in various ubiquitous computing had make portable healthcare system a well known application today. A mobile phone based portable healthcare monitoring system with multiple vital signals monitoring ability at real time in WSN and CDMA network is developed. This system carries out real time monitoring and local data analysis process in the mobile phone. Any detection of abnormal health condition and diagnosis at earlier stage will reduce the risk of patient's life. As an extension to the existing model, a pre-diagnosis management system (PDMS) is designed to minimize the time consuming in pre-diagnosis process in the hospital or healthcare center. An alert is sent to the web server at the healthcare center when the patient detects his health is at critical state where the immediate diagnosis is needed. Preparation of diagnosis equipments and arrangement of doctor and nurses at the hospital side can be done earlier before the arrival of patient at the hospital with the help of PDMS. An efficient pre-diagnosis management increases the chances of diseases recovery rate as well.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.12
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• pp.935-941
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• 2018

In this study, we propose a suitable magnetic resonant wireless power transfer(WPT) system topology for size-limited implant medical devices(IMDs). The proposed modified series-parallel topology(mSPT) can be implemented by adding an inductor in series to the parallel-connected Rx coil and a capacitor. The topology achieves high efficiency when the Rx coil has a small inductance. The validity and operating conditions of the system are verified theoretically through circuit analysis. Experiments were conducted with bio-blocks, which are made of pork fat and muscle. When the Rx coils were inserted into the blocks at a depth of 2.5~10 mm, mSPT showed 17.79 % improved efficiency on average compared with the conventional series-series topology(SST). In the case of 32 dBm WPT in air, the Rx coil's heating rate for the mSPT was $0.18^{\circ}C/s$, whereas the SST was $0.75^{\circ}C/s$. It was confirmed that the mSPT is more suitable for an IMD-targeted WPT system.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.3
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• pp.83-89
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• 2023

The clustering technique using RF fingerprint extracts the characteristic signature of the transmitters which are embedded in the transmission waveforms. The output of the RF-Fingerprint feature extraction algorithm for clustering identical DMR(Digital Mobile Radios) is a high-dimensional feature, typically consisting of 512 or more dimensions. While such high-dimensional features may be effective for the classifiers, they are not suitable to be used as inputs for the clustering algorithms. Therefore, this paper proposes a dimension reduction algorithm that effectively reduces the dimensionality of the multidimensional RF-Fingerprint features while maintaining the fingerprinting characteristics of the DMRs. Additionally, it proposes a clustering algorithm that can effectively cluster the reduced dimensions. The proposed clustering algorithm reduces the multi-dimensional RF-Fingerprint features using t-SNE, based on KL Divergence, and performs clustering using Density Peaks Clustering (DPC). The performance analysis of the DMR clustering algorithm uses a dataset of 3000 samples collected from 10 Motorola XiR and 10 Wintech N-Series DMRs. The results of the RF-Fingerprinting-based clustering algorithm showed the formation of 20 clusters, and all performance metrics including Homogeneity, Completeness, and V-measure, demonstrated a performance of 99.4%.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1408-1415
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• 2007

To operate Platform Screen Door (PSD) automatically, the operational data of PSD and the train must be interfaced properly. PSD and train are operated together by the signaling system in Automatic Train Operation (ATO) signaling system zone where interfaces are provided between PSD and train. However, the additional PSD interface system with train is required in train operating zone without the interface between PSD and train. For the PSD interface, the wireless communication system or the train status (train correct stop status / train door status) detection system has been used. Seoul Metro line No.2. has the PSD wireless communication system using 447MHz band RF. For the safety of PSD operation, it is required to prevent RF interference in the subway environment where many frequencies exist. In this paper, the PSD wireless communication system is developed using 2.4GHz band RF to prevent the interference of the wireless communication and increase the traffic of the PSD interface. Furthermore, the improved system can store, manage and display the PSD and train operational data using Human Machine Interface (HMI) in the train's driver cab.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1209-1212
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• 2008

The high-speed EMU is assembled with distributed EMI sources. Therefore, it contains more electromagnetic sources nearby the distributed victims than the existing concentrated traction system. The electromagnetic sources and victims are identified in this research, and the methodology how to handle EMI/EMS/EMC of the high-speed EMU will be developed for safer operation. It includes measurement method, safety standards of control units and others, and performance evaluations of the firstly developed trial products for the EMU. Also influences by modern telecommunication equipments and effect of PLD(power line disturbance) are to be surveyed in this research.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.1
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• pp.233-240
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• 2011

A field server was developed by using ubiquitous sensor network technology to monitor the abrupt weather variation in local or mountain area. The data transmissions between deployed field servers in local terrain are very important technology in disaster prevention monitoring system. Weather related information such as temperature, humidity, illumination, atmospheric pressure, dew point and meteorological data are collected from the designated field at a regular interval. The received information from the multiple sensors located at the sensor field is used flooding routing protocol transmission techniques and the sensing data is transferred to gateway through multi-hop method. Telosb sensor node are programmed by nesC language in TinyOS platform to monitor the weather parameters of the local terrain.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.3
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• pp.60-66
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• 2011

The$PM_{10}$ concentrations in the underground should be monitored for the health of commuters on the subway system. Seoul Metro and Seoul Metropolitan Rapid Transit Corporation are measuring several air pollutants regularly. In this paper, the reliability of the instruments using light scattering method is improved with the help of a linear regression analysis technique to measure the $PM_{10}$ concentrations continuously in the subway stations. In addition, an USN monitoring system is implemented to display and record the data of $PM_{10}$, CO/$CO_2$, humidity, and temperature. To transmit and receive these measured sensor data, 2.4GHz Zigbee, 424MHz wireless communication, and CDMA M2M method are applied and evaluated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.8
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• pp.688-696
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• 2013

In wireless sensor networks, real-time applications have to ensure the timely delivery of real-time data. Recently, OMLRP (On-demand Multi-hop Look-ahead Routing Protocol) has been proposed to improve the timeliness of wireless sensor networks. The protocol needs initialization time to establish multi-hop information based routing path because it performs incremental look-ahead of the information. Consequently, the protocol deteriorates DDSR (Deadline Delivery Success Ratio) as an event moves because it takes little consideration of event mobility. In this paper, we proposed a Real-time Routing for Events Mobility (RREM) which exploits a data redirection in order to improve the DDSR of moving events. Instead of recollecting muti-hop look-ahead information, the RREM redirects the data to a sensor node holding the information collected in a previous round. We verify the timeliness and energy efficiency of RREM using various MatLab simulations.