• Journal of the Korea Society of Computer and Information
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• v.10 no.1 s.33
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• pp.167-174
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• 2005

With the progress of portable appliances such as cell phone and handhold PC, the popularization of Personal Area Network (PAN) and the diversification of services that are based on Personal Mobile Gateway (PMG) . To use home services at any time regardless of their Position, it needs a virtual home network that a home network and outside networks are finally integrated. Although interoperability among home appliances reached their service stage, research for services and middleware for new small scale network such as PAN is at an early stage. Traditional home network service/connection methods, terminal control schemes, and middlewares must be extended to accommodate PMG-based PAM. In this paper, we propose an integrated virtual home network Platform that guarantees seamless connections between home network and PAM. We also analyze indispensable functions and presents functions that should be added existent home gateway or home sewer by function.

• Journal of the Korea Society of Computer and Information
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• v.19 no.2
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• pp.101-107
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• 2014

This study is proposed the novel PPG sensor device and the signal processing method to replace the acceleration sensor that is used to reject motion artifacts contained in photoplethysmography(PPG). The proposed method is to reject motion artifacts by an adaptive filter based on the estimated motion artifact by using a blue LED light. To evaluate the performance of the proposed method experimentally, We did design a novel sensor consisted of blue/red LEDs and photo-sensor and implemented, and then rejected the motion artifacts by using an adaptive filter and the implemented sensor. In the results of the experiments, it is shown that the proposed sensor device and signal processing can reconstruct the PPG signal despite the occurrence of motion artifacts, and also that the SNR was 4.5 times of moving average filter. According to the experimental results, the proposed method can be applied to design a low-cost device.

• Journal of the Korea Society of Computer and Information
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• v.15 no.8
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• pp.141-148
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• 2010

In mobile terminal recommend service system has general information restrictive recommend that individuality considering to user's information find and recommend. Also it has difficult of accurate information recommend bad points user's not offer individuality information preference recommend service. Therefore this paper is propose user's information individuality preference considering by user's individuality preference recommendation system using improved k-means algorithm. Propose method is correlation coefficients using user's information individuality preference when user's individuality preference recommendation using improved k-means algorithm. Restrictive information recommend to fix a problem, information of restrictive general recommend that user's information individuality preference offer to accurate information recommend. Performance experiment is existing service system as compared to evaluating the effectiveness of precision and recall, performance experiment result is appear to precision 85%, recall 68%.

• Journal of the Korea Society of Computer and Information
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• v.15 no.8
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• pp.23-30
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• 2010

Flash memory is non-volatile and can retain data even after system is powered off. Besides, it has many other features such as fast access speed, low power consumption, attractive shock resistance, small size, and light-weight. As its price decreases and capacity increases, the flash memory is expected to be widely used in consumer electronics, embedded systems, and mobile devices. Flash storage systems generally adopt a software layer, called FTL. In this research, we proposed a new FTL mechanism for overcoming the major drawback of conventional block mapping algorithm. In addition to the block mapping table, a index block mapping table with a small size is used to indicate sector location. The proposed indexed block mapping algorithm by adding a small size. By the simulation result, the proposed FTL provides an enhanced speed than a conventional hybrid mapping algorithm by around 45% in average, and the requirement of mapping memory is also reduced by around 12%.

• Journal of the Korea Society of Computer and Information
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• v.12 no.1 s.45
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• pp.189-197
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• 2007

Developed safety system which transfers danger information to rear cars for accident prevention when drivers detect a accident, a dropping or a freezing during driving on the high way. To prevent an accident, each vehicles mount OBU which is made up of a GPS unit and a transmitter-receiver and the trace of road is always renewed and saved in OBU per a regular past distance. When the driver see dangerous situation, transfer a danger pattern and a trace information by pressing button. All cars which receive information compare the received data with the original data. And then, only cars which are located at the rear in a regular distance respond and occur a warning. Performed a road test at the rate of $30{\sim}50$ kilometer a hour using two test cars which saved about 120meter's space between them were mounted OBU which had 447Mhz transceiver. As a result of the experiment, communication between test cars had no problem. Accordingly, it can use a safety driving device because driver can notice a danger situation and set themselves ready for it using this system in advance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.9
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• pp.1694-1701
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• 2007

Recently The biggest three mobile telecommunication companies of our country still using independence wireless internet platform. And, It can so many difficulties to the phone company and content provide company. Such as the timing of the development or the fee of the development. Because even they develop one product and Hey must make it prepare for some platform of every mobile telecommunication companies. And this make the development more longer and more expensive. For this reason, SKT, LG telecom and KTF develop the new wireless internet platform named WIPI with ETRI. and the working is still go on and go ahead with propulsion. And if it come to reality, the WIPI will attached from much of attack such as hacking or virus. But some data exchange between mobile phone is so important as to flow. Thus, in this paper, we consideration the XML using in the wireless environment and we are design and implementation the XML encryption system working at the WIPI in order to protect the data, we want to protect.

• Journal of the Korea Society of Computer and Information
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• v.11 no.4 s.42
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• pp.155-164
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• 2006

VoIP technology is Eight New Services among Ubiquitous-IT839 strategies. This paper tested wiretapping or VoIP service in connected a soft phone and LAN and WAN sections, Internet telephones and a device. IP PBX, a banner operator network to have been connected to VoIP Internet network. As a result of having experimented on wiretapping of VoIP networks, Vulnerability was found. and a wiretapping by attacks of a hacker was succeeded in a terminal and proxy and attachment points of a VoIP network like a hub to follow a CVE list. Currently applied a security plan of an each wiretapping section in viewpoints of 6 security function of Access Control. Confidentiality, Authentication. Availability, Integrity. Non-repudiation in VoIP networks named to 070. Prevented wiretapping of contents by the results, the AES encryption that executed wiretapping experiment about a packet after application of a security plan. Prevented wiretapping, and kept security and audit log. and were able to accomplish VoIP information protection to network monitoring and audit log by an access interception and qualification and message hash functions and use of an incoming refusal.

• Journal of the Korea Society of Computer and Information
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• v.11 no.3
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• pp.1-10
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• 2006

It is widely accepted that the coverage with high user densities can only be achieved with small cell such as micro- and pico-cell. The smaller cell size causes frequent handovers between cells and a decrease in the permissible handover Processing delay. This may result in the handover failure. in addition to the loss of some Packets during the handover. In these cases. re-transmission is needed in order to compensate errors, which triggers a rapid degradation of throughput. In this paper, we propose a new handover scheme in the next generation mobile communication systems, in which the handover setup process is done in advance before a handover request by predicting the handover cell based on mobile terminal's current position and moving direction. Simulation is focused on the handover failure rate and Packet loss rate. The simulation results show that our proposed method provides a better performance than the conventional method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.104-107
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• 2014

Nowadays, smart devices such as smart phones, tablets PC, etc... are exchanging messages using WLAN(Wi-Fi) technologies for sending and receiving messages. With the growth of the smart devices users, the WLAN (Wi-Fi) medium communication could be loaded and then the Quality of Service is undesirable. Currently, there are five types of Wireless LAN such as802.11 a / b / g / n / ac supporting the communication between smart devices and the most used it WLAN 802.11n. Unfortunately, if the WLAN 802.11n is being used by a lot of users, there is poor Quality of Service due to the interference. In this paper, we analyze the Quality of Service provided by the 802.11n and compare with the next generation of wireless 802.11ac.

• Journal of the Korea Society of Computer and Information
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• v.25 no.12
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• pp.173-186
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• 2020

In this paper, we design and implement a service system for mobile devices to utilize the integrated underground geospatial information map in underground exploration fields. The field utilization service system for mobile devices is designed to visualize tiled maps, 3D terrain information, underground structures, underground facilities, and ground information provided by the Integrated Underground Geospatial Information Map Management System according to current position. And It is designed to reflect the results obtained from field exploration in real time. Also, the proposed system is implemented to transfer and visualize the integrated underground geospatial information map in the form of a glTF format due to constraints on wireless networks and device characteristics of mobile devices. Implemented mobile service systems can prevent accidents in underground exploration field from occurring by providing users with accurate and integrated underground geospatial data by visualizing maps and geospatial objects in three dimensions at underground exploration fields. In addition, updated underground geospatial data is transmitted in real time to the Integrated Underground Geospatial Information Map Management Systems, which can maintain up to date and accuracy.