• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.249-254
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• 2005

This paper presents the design of a novel small and wide band planar inverted F-antenna which simultaneously covers GSM900/GPS/DCS1800/DCS1900/DMB service. The proposed antenna consisting of a main patch with rectangular slit, strip 1 and strip 2, occupied the total volume of.$15\times36\times6mm^3$. A very wide impedance bandwidth characteristic was achieved by optimizing both the distance between the feed line and short strip and the length of rectangular slit on the main patch. The commercial electromagnetic software, CST Microwave Studio, is used to design the structure. The maximum gains at the frequencies of 900, 1575, 1800, 1900, and 2600 MHz were 2.07, 1.07, 1.69 and 0.55, -1.99 dBi, respectively. The overall shape of the radiation patterns is suitable for mobile communication application.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.12
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• pp.1269-1273
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• 2010

Typically users prefer to manage and access personal photo collections taken from a cell phone based on events. In this paper we propose an event clustering algorithm that requires low computation cost with high accuracy supporting incremental operation. The proposed method is based on the statistical analysis of the elapsed interval of intra-event photos on the real sample data for the decision of an event boundary. We then incorporate both location and visual information for the ambiguous range to split with only temporal cue. According to test results, we show higher performance compared to existing general clustering approaches.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.8
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• pp.1171-1177
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• 2013

Since existing location-based services suggest a search result, not considering user's environment, intention, or preference, situational awareness is required to resolve this problem. In this paper, an Android-based situational-awareness dynamic scheduling will be suggested and a tourist information service application will be embodied and tested. In other words, a real-time tourist scheduling service that calculates an estimated travel time from user's location to destination and reminds a user before the expected departure time will be developed. In addition to tourist information, an added scheduler provides convenience and improves its functionality.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.5
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• pp.498-509
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• 2015

The existing mobile antenna networks in the military use have been operated by the manual pointing between two antennas. The work presented here describes the study of ATPC(Automatic Tracking and Pointing Control) system between facing antennas and the related tracking and pointing performances. This system is able to automatically track the maximum RSSI(Received Signal Strength Indication) value from the source's RF(Radio Frequency) signal and then control for maintaining the LOS(Line of Sight) between two antennas. The system has three major units; the driving unit consisting of motors, harmonic drives and encoders, the sensor unit with a GPS(Global Positioning System) and AHRS(Attitude and Heading Reference System) and the control unit regulating all the tracking and pointing events. By using PI(Proportional and Integral) controller, this system is able to properly track and point the other antenna under the external disturbance like the wind load. Both the simulation and the experimental works have been successively carried out to prove the performances of the system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.4
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• pp.853-871
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• 2012

The location based service is divided into GPS that uses the artificial satellite or base transceiver station in order to cover the wide area and RTLS(Real Time Location System) using the Zigbee, RFID, CSS(Chirp Spread Spectrum), UWB, Bluetooth and Wi-Fi equipment in the space(close range) limited like the building inside or park. Moreover it also repeats the technical development upon through the acceleration of the development of the wire and wireless infrastructure and determination technology, the development of the Internet, diversification of the contents, and etc. As a result, it is expected to develop around the determination technology, witch is common core technology element, contents technology, Internet and mobile communication technology, and etc. afterward. In this research, the direction we investigate was to find and analyze new technology and standardization trend of LBS in order to contribute to the related industry.

• Journal of Satellite, Information and Communications
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• v.1 no.2
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• pp.83-88
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• 2006

Future communication systems are to be designed to support and serve multimedia and multipledata transmission. Nowadays, requirement of mobile subscribers for the various information such as movie, GPS(Global Positioning System) information, news-is increasing significantly. However, due to practical reasons, the capacity and number of capable channels are limited. To solve this problem, a large number of methods and schemes have been proposed and are under research. In this paper, we demonstrate how satellite DMB (Digital Multimedia Broadcasting) system works with hierarchical modulation scheme. By using hierarchical modulation, we can analyze the capacity. Meanwhile, system performance os evaluated and compared to conventional DMB system without using hierarchical modulation.

• Korean Institute of Interior Design Journal
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• v.19 no.5
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• pp.173-181
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• 2010

Opened on November 2008, as the public exhibition center of a telecommunication company, T.um is dedicated for delivering the future ubiquitous technologies and business vision of the company leading domestic mobile communication business to the global expected clients and business partners. Since the public opening, not only over 18,000 audiences in 112 nations have been visiting T.um, but also the public media have been releasing news regarding the ubiquitous museum constantly. By the reasons, T.um is regarded as a successful case for public exhibition centers. The most distinguished quality of the museum is established by the Location Based Service technology in the initial construction stage. A visitor in anyplace of T.um can be detected by digital devices equipped GPS systems. The LBS system in T.um allows visitors to get the information of relevant technologies as well as the process of how to operating each content at his own spots by smart phone of which wireless network systems make it possible. This study is focusing on analyzing and defining the T.um special qualities in terms of technologies to provide the basic data for following exhibition space projects based on LBS. The special method of experiencing contents can be designed by utilizing the network system applied to T.um in the planning stage.

• IEMEK Journal of Embedded Systems and Applications
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• v.1 no.2
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• pp.82-89
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• 2006

It appears that it is possible for us to make a wireless communication of even home-network system within car by integrating with the Ubiquitous such as mobile phone, wireless Internet, GPS and DMB in the future. If the present wireless surroundings within the car are connected with very high-speed wireless network as measurement system for wireless communication surroundings within this car in the future, it will develop the complicated communication conditions such as safe checkup, communication between systems within car, and wireless communication for user entertainment unlike universal communication conditions. Accordingly, there is the necessity of the device that can measure the interference of electric wave, communication speed and communication quality by a kind of each car. This paper aims at making the real measurement device to raise the reliability of each Application for inquiring into the interference about each other in the frequency band used under Telematics surroundings.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.275-280
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• 2009

Femtocells are viewed as a promising option for mobile operators to improve coverage and provide high-data-rate services in a cost-effective manner Femtocells can be used to serve indoor users, resulting in a powerful solution for ubiquitous indoor and outdoor coverage. TThe frequency accuracy and phase alignment is necessary for ensuring the quality of service (QoS) forapplications such as voice, real-time video, wireless hand-off, and data over a converged access medium at the femtocell. But, the GPS has some problem to be used at the femtocell, because it is difficult to set-up, depends on the satellite condition, and very expensive. The IEEE 1588 specification provides a low-cost means for clock synchronisation over a broadband Internet connection. The Time of Packet (ToP) specified in IEEE 1588 is able to synchronize distributed clocks with an accuracy of less than one microsecond in packet networks. However, the timing synchronization over packet switched networks is a difficult task because packet networks introduce large and highly variable packet delays. This paper proposes an enhanced filter algorithm to reduce ths packet delay variation effects and maintain ToP slave clock synchronization performance. The results are presented to demonstrate in the intra-networks and show the improved performance case when the efficient ToP filter algorithm is applied.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.5
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• pp.73-79
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• 2011

With increasing use of smartphone, users require a new message service to prevent security attack and provide integrated messages. Since smartphone uses data services such as 3G cell network and WiFi, it can provide reliable message transfer through various security policies. In addition, it can transfer various data collected using built-in camera and GPS. This paper proposes a smart message service platform which can provide security services such as authentication, confidentiality and integrity as well as transfer the integrated message including location, picture and text. To verity the functionality of the platform, this paper implements an iPhone app and message transfer server, and then shows the implementation results.