• Archives of design research
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• v.17 no.3
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• pp.441-448
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• 2004

Mobile devices such as mobile phones or PDAs are considered as main interlace tools in ubiquitous computing environment. For searching information in mobile device, it should be possible for user to input some text as well as to control cursor for navigation. So, we should find efficient interlace method for text input in limited dimension of mobile devices. This study intends to suggest a new approach to mobile interaction using camera based virtual keyboard for text input in mobile devices. We developed a camera based virtual keyboard prototype using a PC camera and a small size LCD display. User can move the prototype in the air to control the cursor over keyboard layout in screen and input text by pressing a button. The new interaction method in this study is evaluated as competitive compared to mobile phone keypad in left input efficiency. And the new method can be operated by one hand and make it possible to design smaller device by eliminating keyboard part. The new interaction method can be applied to text input method for mobile devices requiring especially small dimension. And this method can be modified to selection and navigation method for wireless internet contents on small screen devices.

• Journal of Broadcast Engineering
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• v.13 no.2
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• pp.261-273
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• 2008

Multimedia service whose use is rapidly increasing supports effective services to convert and transmit multimedia data based on network speed, noise circumstance, terminal computation, and type of contents for satisfying QoS. For supporting information protection of multimedia service, it offers middle level of singular security service or security mechanism which is based on policy of service provider, depending on present terminal computation and type of contents. It can support security mechanism for more effective multimedia service, if we study security of application layer and network layer for supporting multimedia service. In this paper, we propose Multimedia security framework reflected on quantitative analysis of the WLAN(Wireless Local Area Network) mesh network security using the utility function in the level of the sorority, violation and addictive compensation model.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.6
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• pp.522-528
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• 2017

In this paper, we propose a multi-band antenna for wearable devices using metal frame coupling. The proposed antenna has a $45mm{\times}35mm$ antenna using metal frame and a ground dual coupling structure. The proposed multi-band antenna in this paper is optimized for small devices such as wearable devices. By using the metal frame as a part of the antenna, the volume of the antenna is reduced and satisfies under VSWR 3:1 impedance bandwidth of 70 MHz (870 ~ 940 MHz) in low frequency band, 280 MHz (1600 ~ 1880 MHz) and 280 MHz (1900 ~ 2170 MHz) in high frequency band. It also verified the applicability of wearable devices by measuring wireless performance indicators such as TRP/TIS.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.713-716
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• 2004

In this paper we challenge the user Authentication using Kerberos V5 authentication protocol in Ad-hoc network environment. Ad-hoc network is a collection of wireless mobile nodes without the support of a stationary infrastructure. and DSR routing protocol, which is one of famous mobile ad-hoc routing protocols, has the following network path problem. this paper is the security structure that defined in a mobile network and security and watches all kinds of password related technology related to the existing authentication system. It looks up weakness point on security with a problem on the design that uses Ad-hoc based structure and transmission hierarchical security back of a mobile network, and a server-client holds for user authentication of an application level all and all, and it provides one counterproposal.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.534-537
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• 2006

Currently, The fast development which radio communication technique is creating new services from the industry sector which is various from convenient characteristic and the ease characteristic side. Specially, rise and development of the radio communication technique which is various from environment monitor ring field makes to be improved about sharp curtailment of establishment and logistics relation expense, and collection period of the data which occurs real-time from site, reliability and delivery characteristic. But continuous application and the success about the environment monitor ring field of radio communication technique will be able to trust And It is important to provide time information which is appropriate real-time. So this paper plans the sensor network based on environment measurement watch which applies a radio communication technique.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.2
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• pp.268-275
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• 2014

In this paper, a dual-band circular ring monopole antenna with stub and ground slot for WLAN(Wireless Local Area Networks)/WiMAX(World interoperability for Microwave Access) applications. The proposed antenna is based on a planar monopole design, and composed of one circular ring of radiating patch, cross strip in circular ring, modified feed line, and two rectangular slot in the ground plane for triple-band operation. To obtain the optimized parameters, we used the simulator, Ansoft's High Frequency Structure Simulator(HFSS) and found the parameters that greatly effect antenna characteristics. Using the obtained parameters, the antenna is fabricated. The numerical and experiment results demonstrated that the proposed antenna satisfied the -10 dB impedance bandwidth requirement while simultaneously covering the WLAN and WiMAX bands. And characteristics of gain and radiation patterns are determined for WLAN/WiMAX application.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.10
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• pp.2097-2104
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• 2009

In terrestrial communications, high data rate transmission can be achieved by splitting the coverage area into small cells through base stations and reusing the resource efficiently. However, the geographical features of maritime communications require the long transmission range, and it is not practical to install base station on the sea to set up the similar deployment as the terrestrial communications, so MF/HF band modem with low data rate are currently utilized for maritime communications. And the expensive satellite communication via Inmarsat is the conventional solution for the high data rate transmission on the sea. To reduce the cost, Ad-hoc network is proposed to apply on the sea, which requires no base station for the peer-to-peer communications. In this paper, we denominate this maritime environment specific Ad-hoc network as Nautical Ad-hoc Network (NANET). Furthermore, the deployment scenario for the NANET, and the analysis on multiple access and duplexing schemes for the NANET are discussed in this paper, which serves as the cornerstone for the further NANET research and development.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.8
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• pp.1836-1842
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• 2010

Sensor network, which is technology to realize the ubiquitous environment, recently, could apply to the field of Mechanic & electronic Security System, Energy management system, Environment monitoring system, Home automation and health care application. However, feature of wireless networking of sensor network is vulnerable to eavesdropping and falsification about message. Presently, PKC(public key cryptography) technique using ECC(elliptic curve cryptography) is used to build up the secure networking over sensor network. ECC is more suitable to sensor having restricted performance than RSA, because it offers equal strength using small size of key. But, for high computation cost, ECC needs to enhance the performance to implement over sensor. In this paper, we propose the optimizing technique for multiplication, core operation in ECC, to accelerate the speed of ECC.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.8
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• pp.1861-1868
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• 2014

In wireless communication systems, a frequency offset exist at the received signal due to the transmitter-receiver oscillator mismatch and Doppler effect in mobile environments. Those offsets rotate the received signal's phase and degrade the receiver performance. Hence, estimation and compensation of the frequency offset is crucial at the receiver. This paper proposes a new frequency offset estimation technique based on partial correlation. The proposed method requires less computational complexity than that of the conventional method. In addition, since the proposed one can estimate a wide range of frequency offset without estimation accuracy loss, the application of the method is desirable for the communication environments that have a large frequency offset. In order to verify the performance of our proposed scheme, a series of computer simulations have been carried out and compared against those of the conventional method.

• Journal of Internet of Things and Convergence
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• v.2 no.2
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• pp.21-26
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• 2016

In this paper, it is possible to update the tourist information in real time, on/off-line tour proposes a solution(BBTS) based on a bluetooth beacon can provide tourist information without the need for wireless data network. BBTS consists of a bluetooth based data of the low-power supply system and the beacons and interoperable smart applications. Data supply system consists of the BLE & Beacon Pairing-based / non-pairing data transmission module with integral hardware. Smart application modules that provide indoor location of users information, internal server module and tourist information collection and information guide around comprised of applications. The proposed BBTS is possible that indoor service tourism tourist demand due to utilizing the beacon technology. Outdoor tourist information is designed to be downloaded to the smartphone receives the information received from the beacon APK file to provide services. BBTS system is expected to make a big impact on the smart tourism services industry.