• Journal of Advanced Navigation Technology
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• v.15 no.2
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• pp.197-203
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• 2011

A triple-band antenna which can be used at GSM900, PCS1900 and Bluetooth(or Wi-Fi) frequency band is proposed. The proposed antenna is designed based upon switching between IFA(Inverted F Antenna) that has a resonant length of ${\lambda}/4$ and loop antenna that has a resonant length of ${\lambda}/2$. It can be applied to triple-band only by use of single printed pattern due to the switching characteristic. It is designed by use of the IFA for the application to the GSM900, while it is designed by use of the loop antenna for the application to the PCS1900 and by use of additional pattern of IFA for the application to the Bluetooth(or Wi-Fi) respectively. As a result, it has been observed that the proposed antenna satisfies the required return loss(${\leq}10dB$) and also has efficiency(${\geq}80%$) over the whole band. Moreover the proposed antenna has omni-directional radiation pattern which is suitable to apply to the mobile phone.

• Journal of Advanced Navigation Technology
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• v.18 no.6
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• pp.569-575
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• 2014

Since 2009 the number of users of smart phones and tablet PC is growing exponentially. In particular Apple's iOS and Google's Android OS are the heart of this remarkable growth, most of smart phone and tablet PC are designed to operate based on these two OS. Such increasing use of smart devices has led to changes in the social environment that allows, without the constraints of time and place. However, such development does not supply only ease to do something, even compared to past, financial fraud and information leakage are easier than before by variety of new types of attack for example phishing, pharming, smishing and qshing. So according to this paper, analyzes for smishing attack, propose a countermeasure system of the technical way and proved its higher performance compare to the existing method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.3
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• pp.602-608
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• 2005

We have studied to obtain the SAW filter for the Single Phase Unidirectional Transduce. (SPUDT), was formed on the Langasite substrate and was evaporated by Aluminum-Copper alloy and then we performed computer-simulated by simulator. We can fabricate that the block weighted type IDT as an input transducer of the filter and the withdrawal weighted type IDT as an output transducer of the filter from the results of our computer-simulations. Also, we have performed to obtain the properly conditions about impedance matching of the SAW filter for SPUDT. We have employed that the number of pairs of the input and output IDT are 50 pairs and the thickness and the width of reflector are 5000A and $3.6{\mu}m$, respectively. And the width of IDT' fingers is $2.4{\mu}m$, and the space between IDT' finger and reflector is $2.0{\mu}m$. Frequency response of the fabricated SAW filter has the property that the center frequency is about 190MHz and bandwidth at the 3dB is probably 7.7MHz after when we have matched impedance. Also, we could obtain that ripple characteristics is less than 0.4dB and standing wave ratio is probably 1.5 after when we have matched impedance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.716-719
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• 2003

P2P (Peer to Peer) is part that is discussed much in the latest Internet and is interested. P2P changes the structure of Client-Server into Information sharing between client that is the structure of p2p. But perfect P2P system has many problems awaiting solution. In this treatise we can realize network communication to compose one virtual server and one virtual client which is intergrated several client and distributed computer that decentralize network traffic into the traffic of several pc by sharing resource and cpu between client. Our nam purpose is not real P2P system but realization, organization of the P2P internet system which is composed by distributed computing and network load balancing in P2P internet system environment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.3
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• pp.564-570
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• 2006

This paper presents a new real-time system design methodology for embedded system as well as event-driven real time application. It is required to implement a deadline handling mechanism in order to satisfy a large-scale distributed real time application. When we design real time system, it has handled a deadline and is important to measure / control a timing issue. These timing constraints usually associated with an interface between model and system. There are many case tools that supporting a real time application, for example, UML, graphic language for designing real time system, but they cannot provide efficient way to handle deadline miss. Therefore, users have to design deadline handler manually when they need to use it. This paper contributes solving the problems of user-level deadline handling for an embedded system. Also, it also discusses an efficient deadline handler design mechanism using on RoseRT, which is a graphical CASE tool supporting from UML.

• Journal of Navigation and Port Research
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• v.33 no.10
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• pp.743-756
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• 2009

This paper tries to analyze how the governance institutions of the Port Authority of New York and New Jersey overcome agent problems in public agencies based on the Principal-Agent Theory, and find the implications that will be helpful to the governance of port authorities in Korea. The Port Authority's governance is characterized by decentralization of personnel rights, open meetings policy, freedom of information policy, public hearings, and fiscally self-supporting system. Those characteristics are helpful in overcoming the agent problems of public agency, such as adverse selection, moral hazard, and complicated external structure, through reinforcing of monitoring agent by principal, easing of information asymmetry between principal and agent, and clarification of organizational ownership structure. Those characteristics may give many implications for the design of governance structures of port authorities in Korea.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.901-904
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• 2007

Nowadays, in many fields of medical treatment, we can make an observation and a diagnosis of inward disease without using a surgical operation. As one of them, ultra-sound diagnosis system can be available widely in its cost and size compared with other medical instruments. This system also make it possible for us to see the inner parts of the body in real time harmlessly for a long time. So it can be utilized to inspect the movement of heart or fetus and to diagnose an internal disease of the soft tissues. Ultra-sound images can be generated by the reflexive and scattered wave through the pulse generator and so in ultrasound images there exist inherently many affective noised signals. In this paper, we are to take an noise-restrained image and to extract a more affective regions of the images.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.7
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• pp.680-687
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• 2008

This paper presents map creation algorithm and initial attitude estimation method for the proposed optical head tracker system. The optical head tracker system consists of the IR stereo cameras and infrared LEDs as features on the helmet. In order for the stereo camera to track the luminous LEDs, it must take in to account the light radiation from the LEDs to determine the position of the center points. The proposed map creation algorithm makes map data about the position of features center points on the helmet frame. Also, initial attitude estimation method is proposed to estimate the initial attitude and position of a pilot head from the camera frame by the use of the feature pattern on the helmet. Therefore, the head motion can be expressed with respect to the body frame of a flight.

• Journal of Broadcast Engineering
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• v.13 no.4
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• pp.528-543
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• 2008

Internet Protocol Television (IPTV) provides an interactive and personalized service for realizing integrated broadcasting and telecommunication services. Set-top box (SIB) connected to TV is an essential component required for IPTV and has a unique hardware identifier used in identification and authentication. It means that subscriber authentication based on box-level identification is inconsistent with IPTV's main intention of providing personalized services. The proposed solution is to provide an opportunity to use the flexible user-centric authentication mechanism through Java Card applets in IPTV application server and 3G networks. This paper suggests personalized services by moving the user's private data and authentication management beyond the STB to a truly personalized device, the ubiquitous mobile phone. In addition, this paper presents effectiveness and security analysis for verifying the proposal.

• The Journal of Korean Institute for Practical Engineering Education
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• v.2 no.2
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• pp.42-48
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• 2010

For a basic engineering education Problem-Based Learning (PBL) method was adopted in order to pursuit the learner acquisition of critical knowledge, problem solving proficiency, and self-directed learning strategies by measurements of various physical and biological units, by calculation of errors in experimental data, by leraning energy conservation law and equation of motion, and, by analysis ability on data patterns through Elliptical Trainer(ET) exercise. The results show the ET may be a good experimental tool for understanding the PBL method. A sample syllabus was provided for one semester use, and by use of data obtained by self-directed and creative learning, the results of three groups for the PBL problems proposed by using ET were (1) the slope of angle was 23.5o in the diagram of energy exhaustion against velocity (GROUP A), (2) the angle range between the maximal and minimal energy exhaustion against weight loss was 15.0o ~ 26.5o (GROUP B), and finally (3) the angle was varied by 51.0o in the diagram of weight loss against distance (GROUP C).