• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.539-541
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• 2016

In this paper, we proposed real time free-length monitoring systems interlocking with the spring free-length sorter which shows the state of production connected to the spring production device. This systems enable the administrator to check the quality or quantity of product and the defect rate, etc., in the remote place. The proposed systems are comprised of the wireless device interlocking with PLC device, the server program, and user GUI program. The wireless device transmits the received data from PLC device to server program using Wi-Fi. Server program represents the data from the wireless device on the screen and insert those data into database. User GUI program shows data stored in database and supports the function which converts the stored data in DB to excel file.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.3
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• pp.551-558
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• 2015

As more people use Wi-Fi and hotspot, unauthorized APs become one of big security problems in modern society. From the beginning of 2010, researchers study about unauthorized AP continually and contributed a lot of methods of detecting unauthorized AP that use wireless resources. Many researches about unauthorized AP detection use time-delay measurement (e.g., average or standard deviation) which is caused by additional wireless connection. In the most previous researches, however, the unauthorized APs consist of laptop and pulg-in Wi-Fi adaptor, and researchers did not concern about time-delay caused by software network sharing. In this paper, we show that existing unauthorized AP detection scheme that can not efficiently classify the high performance unauthorized AP.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.265-274
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• 2011

In this paper, it is studied on wide radiating slot antenna's miniaturization for ultra wide-band(UWB) technologies and notch structure to prevent interference between UWB systems and existing wireless systems for using Wi-Fi service of IEEE standards 802.11 a/n. Proposed antenna that wide slot is decreased from $\lambda/2$ to $\lambda/4$ length of resonant frequency has decreased by 72 % compared with conventional antenna. And optimized T-shaped CPW-fed stub has satisfied UWB bandwidth for 3.0~11.8 GHz. Then, creating 2-order Hilbert curve slot line in the stub's patch area, 4.9~5.6 GHz that centered frequency is 5 GHz is eliminated. Finally, the designed antenna constructed on FR4-epoxy has $20{\times}15\;mm^2$ dimension. The measured results that are obtained return loss under -10 dB through 3.2~11.8 GHz without Wi-Fi bandwidth, a linear phase characteristic, a stable group delay, and omnidirectional radiation patterns are presented.

• International journal of advanced smart convergence
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• v.1 no.2
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• pp.59-63
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• 2012

The mVoIP service is the technology which focuses on the wireless data service as the IP network having the transmission rate of 100 Mbps classes on the high-speed middle of movement through the WiFi, WiBro and 3G mobile radio communication network, and etc. and is developed. Since 2010, the mVoIP (mobile VoIP) service shows the rapid growth due to 4G-LTE service seriously disclosed from July with the Smart phone and 2,011 it begins to be rapidly popularized. In this research, additionally the mVoIP service industry activation plan is presented with the trends of technology development including the chip-set/module/terminal, etc. based upon local and foreign market trend searchlight through the market demand analysis. The mVoIP service downloads App to the mobile apparatus and or can provide the service as the software through the WiFi network. Therefore, the change which is large in the products development aspect is to be have no. Expected to is being provided as the added service in the case of 4G-LTE as a matter of course, the service deployment where it is based on the market principle and demand needs is needed.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.97-101
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• 2008

Voice over IP is a telephone service which sends and receives the voices through the Internet. Because the infrastructure of wireless and mobile communication networks such as 3G, Wi-Fi and WiMAX has expanded, the study about Mobile VoIP, which provides the voice service from wireless network, has been actively in progress. Since Rei 6 HSPA in 3GPP and Rev A lxEVDO in 3GPP2, VoIP through the data channel is more efficient than circuit switch. It is predicted that VoIP over 4G will be more effective and 4G mobile VoIP business will be vitalized in the future. In addition, there are businesses which offer VoWLAN by using software such as Skype and Fring. They provide services which cheapen the price of international calls and long distance calls. This paper will present the Korean and other countries' mobile VoIP trends, its classification along the network connection, the study on techniques, and conditions of mobile VoIP. It also will be described a view of terminal convergence and service convergence.

• Nuclear Engineering and Technology
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• v.47 no.6
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• pp.729-737
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• 2015

Wireless communication technologies, especially smartphones, have become increasingly common. Wireless technology is widely used in general industry and this trend is also expected to grow with the development of wireless technology. However, wireless technology is not currently applied in any domestic operating nuclear power plants (NPPs) because of the highest priority of the safety policy. Wireless technology is required in operating NPPs, however, in order to improve the emergency responses and work efficiency of the operators and maintenance personnel during its operation. The wired telephone network in domestic NPPs can be simply connected to a wireless local area network to use wireless devices. This design change can improve the ability of the operators and personnel to respond to an emergency situation by using important equipment for a safe shutdown. IEEE 802.11 smartphones (Wi-Fi standard), Internet Protocol (IP) phones, personal digital assistant (PDA) for field work, notebooks used with web cameras, and remote site monitoring tablet PCs for on-site testing may be considered as wireless devices that can be used in domestic operating NPPs. Despite its advantages, wireless technology has only been used during the overhaul period in Korean NPPs due to the electromagnetic influence of sensitive equipment and cyber security problems. This paper presents the electromagnetic verification results from major sensitive equipment after using wireless devices in domestic operating NPPs. It also provides a solution for electromagnetic interference/radio frequency interference (EMI/RFI) from portable and fixed wireless devices with a Wi-Fi communication environment within domestic NPPs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4884-4890
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• 2015

These days most of people possesses an average of one to two mobile devices in the world and a wireless network market is gradually expanding. Wi-Fi preference are increasing in accordance with the use growth of mobile devices. A number of areas such as public agencies, health care, education, learning, and content, manufacturing, retail create new values based on Wi-Fi, and the global network is built and provides complex services. However, There exist some attacks and vulnerabilities like wireless radio device identifier vulnerability, illegal use of network resources through the MAC forgery, wireless authentication key cracking, unauthorized AP / devices attack in the next generation radio network environment. In addition, advanced security technology research, such as authentication Advancement and high-speed secure connection is not nearly progress. Therefore, this paper designed a secure communication system for message protection in next-generation wireless network environments by device identification and, designing content classification and storage protocols. The proposed protocol analyzed safeties with respect to the occurring vulnerability and the securities by comparing and analyzing the existing password techniques in the existing wireless network environment. It is slower 0.72 times than existing cypher system, WPA2-PSK, but enforces the stability in security side.

• Journal of Advanced Information Technology and Convergence
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• v.10 no.2
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• pp.73-81
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• 2020

The number of mobile devices roaming into a ubiquitous city (u-city) continues to rise as wireless systems have been widely deployed. The number of mobile devices also varies with time, and they tend to frequently change their locations. In addition, the available wireless access networks may belong to different domains, administrations, management, and internet service providers (ISPs). A fusion of overlapping heterogeneous wireless access networks (e.g., WiMax, Wi-Fi, LTE, etc.) serves the u-city in order to reach different coverage. In this context, technical challenges arise in mobility management for heterogeneous networks to realize their potential coverage and capacity benefits. This paper deals with the analysis of a decentralized mobility management support for u-City wireless network infrastructure. This scheme takes advantage of the features of the fully-distributed model of networked-based mobility management protocol to alleviate and realize the ubiquitous requirements of a u-City.

• Journal of the Korea Society of Computer and Information
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• v.16 no.12
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• pp.227-234
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• 2011

Many technologies for wireless internet are increasing as more and more laptop computers, net books, smart phone and other terminals, which provide wireless network, are created. IEEE 802.11 is computer wireless network technology that used in small area, called wireless LAN or Wi-Fi. IEEE 802.11 is a set of standards for implementing wireless local area network (WLAN) computer communication in the 2.4, 3.6 and 5 GHz frequency bands. They are created and maintained by the IEEE LAN/MAN Standards Committee (IEEE 802). AP (Access Point) is installed at cafes and public places providing wireless environment. It is more convenient to use wireless internet, however, It can be seen easily around us and possible to communicate with AP. IEEE 802.11 has many vulnerability, such as packet manipulation and information disclosure, so we should pay more attention when using IEEE 802.11. Therefore this paper developing monitoring system which can find out AP and Stations that connect with it, and capturing AP's information to find out vulnerability. This paper suggests monitoring system which traffic analysis in wireless environment.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.64-69
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• 2013

Recently, users who are interested in the service at indoor spaces is increasing. An indoor positioning system can minimize a range of positioning error using a variety of wireless communication infrastructure. Also, the system improves an indoor positioning accuracy by combining a mobile communication network. However, flexible positioning technologies regardless of an environment are insufficient. Therefore, this is time for a systematic study on an indoor positioning system business model. This paper classify differences between an indoor positioning system technology and outdoor positioning system technology. And we research a construction and application of the indoor positioning system that is adapted a wireless communication system (Wi-Fi, Bluetooth, RFID, UWE, Fingerprint, etc.) in domestic and foreign. We present a successful model of indoor positioning system and the development for future systems.