• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.13 no.10
• /
• pp.982-988
• /
• 2002

This paper summarizes the design concepts and implementation of a Ku-band channel amplifier's engineering model for the communication and broadcasting satellite applications. The selected architecture uses the analog gain control for the FGM(Fixed Gain Mode) and the output level limiting using automatic loop control for the ALC (automatic level control) mode. The Ku-band channel amplifier incorporates several state-of-the-art components including voltage-controlled PIN diode attenuators, and various temperature-compensation circuits. The measured characteristics of the Ku-band channel amplifier are in good agreement with the expected performance. The results show a fixed gain control of 28 dB, and an automatic level control of 16 dB over operating temperature range. The designed engineering model could be used as a channel amplifier for Ku-band communication and broadcasting satellite payload system.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.15 no.3
• /
• pp.324-329
• /
• 2005

In this paper, a robust $H\infty$ stabilization problem to a uncertain discrete-time nonlinear systems with time-delay via fuzzy static output feedback is investigated. The Takagj-Sugeno (T-S) fuzzy model is employed to represent an uncertain nonlinear system with time-delayed state. Then, the parallel distributed compensation technique is used for designing of the robust fuzzy controller. Using a single Lyapunov function, the globally asymptotic stability and disturbance attenuation of the closed-loop fuzzy control system are discussed. Sufficient conditions for the existence of robust $H\infty$ controllers are given in terms of linear matrix inequalities via similarity transform and congruence transform technique. We have shown the effectiveness and feasibility of the proposed method through the simulation.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2010.07a
• /
• pp.23-26
• /
• 2010

In this paper, we propose a new method for the design and implementation of a web-based 3D fashion shopping mall. Web 3D shopping mall is implemented by using a Web3D authoring tool, ISB, which provides easy mouse operation. 3D human models and cloth item model are designed by low polygon modeling method of 3D MAX. The designed 3D human models and cloth item model are exported to XML file. Finally, 3D human models and cloth item model are displayed and animated on the Web by using ActiveX control based on DirectX. We also implemented textile palette and mapped it to clothes model by using alpha blending during simulation.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.49 no.7
• /
• pp.6-11
• /
• 2012

A mobile station(MS) in an 802.16e network manages its limited energy using the sleep mode operation. An MS can power down its physical operation components during the unavailability interval of the sleep mode. To reduce energy consumption by increasing the unavailability interval, this paper proposes an enhanced power saving mechanism(ePSM) when both activated Type I and Type II power saving classes(PSCs) exist in an MS. A performance evaluation confirms that ePSM results in the improved performance in terms of the unavailability interval as well as the energy consumption than conventional schemes.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.8 no.4
• /
• pp.70-77
• /
• 1997

최근 전파통신 기술의 급속한 발전과 경제적 수준의 향상에 따라 다양한 무선국에 대한 수요가 증가한고 있는 가운데 미약한 전력의 전파를 발사하는 미약무선국은 무선국 개설시 허가나 신고가 필요없는 무선국으로 산업활동과 일상생활 속에서 좁은 서비스 반경을 가지고 음성 및 데이터 전송용, 장비의 원격제어용 등의 용도로 사용범위가 확산되어가고 있는 추세이다. 미약무선국의 폭넓은 활용은 국내 전파산업의 육성과 국민의 사회적 활동 및 일상생활의 편의도모등, 많은 긍정적인 효과를 가지고 있지만 무분별한 미약무선국의 사용으로 인한 전파발사는 무선국의 상호간에 간섭을 일으켜 통신품질을 현저히 낮게 하거나 통신자체를 불가능하게 만드는 등 심각한 부작용을 초래할 수 있다. 그러므로 각 국은 미약무선국의 발사 전파로 인한 간섭으로부터 기존의 무선국을 보호하고 한정된 주파수 자원을 효과적으로 사용하여 관련 전파산업의 건전한 발전과 육성을 도모할 목적으로 미약무선국의 사용 주파수와 그에 따른 발사전파의 출력을 제한하는 관련 전파법규를 가지고 있다. 국내의 경우는 전파법 시행령 제56조 2항 1호에 측전거리 3미터를 기준으로 사용 주파수 대별로 전계강도 기준값이 설정되어 있고 2호에는 500미터 전계강도 기준값이 규정되어 있는데, 본 글에서는 전파법 시행법 제 56조 2항 1호와 2호에 해당하는 무선국을 미약무선국이라고 정의한다.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.3 no.1
• /
• pp.8-14
• /
• 1998

This paper describes a novel real-time based optimal Pulse Width Modulation (PWM) method suitable for microprocessor-based PWM inverters. Optimal switching patterns minimizing the performance index corresponding to the distortion between the reference and the controlled output voltages are decided by on-line calculation using the microprocessor-implemented control system. To show the effectiveness of the proposed PWM scheme, digital simulation studies and experiments using a 16-bit single-chip microcontroller (Intel 80C196KC) are performed. The results obtained from these simulation studies and experiments show that the proposed PWM scheme has better performance than the other methods such as the natural PWM and the direct PWM.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.15 no.6
• /
• pp.460-465
• /
• 2010

The interest is coming to be high, recently with depletion of the fossil fuel and with carbon dioxide exhaust limit about emittion, from a car of Internal combustion engine to Electric vehicle. AC-DC converter is necessary to battery charging which is an electric vehicle energy storage. Necessary conditions of the converter are necessary for wide output voltage range, high efficiency, high power factor etc. It is composed two stages for wide output voltage range and insulation. Preliminary stage uses LLC resonant converter and the after stage uses BOOST converter PFC circuit for being considered a power factor and confirmed experimentally.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.5B
• /
• pp.443-448
• /
• 2009

A boundary value of the velocity of data gathering node (DGN) and a critical value for training overhead beyond which the scheme will not be feasible for a Multiple Input Multiple Output (MIMO) based cooperative communication for energy-limited wireless sensor networks is proposed in this paper. The performance in terms of energy efficiency and delay for a combination of two transmitting and two receiving antennas is analyzed. The results show that a set of critical value of velocity and training overhead pair is present for the long haul communication from the sensors to the data gathering node. Finally a relation between training overhead and velocity is simulated.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.4 no.4
• /
• pp.311-317
• /
• 2011

Recently, RFID is substituted for bar codes according to advance in the ubiquitous computing environments, but the RFID system has several problems such as security and privacy because it uses radio frequencies. Firstly, unauthorized reader can easily read the ID information of any Tag. Secondly, Attacker can easily fake the legitimate reader using the collected Tag ID information,such as the any legitimate tag. This paper proposed improved RFID authentication protocol based on SSG. SSG is organized only one LFSR and selection logic. Thus SSG is suitable for implementation of hardware logic in system with extremely limited resources such as RFID tag and it has resistance to known various attacks because of output bit stream for the use as pseudorandom generator. The proposed protocol is secure and effective because it is based on SSG.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• v.9 no.1
• /
• pp.167-170
• /
• 2005

In the mobile environments for the vector map services, a map simplification work through the map generalization steps helps improve the readability of the map on a large scale. The generalization operations are various such as selection, aggregation, simplification, displacement, and so on, the formal operation algorithms have not been built yet. Because the algorithms require deep special knowledge and heuristic, which make it hard to automate the processes. This thesis proposes some map generalization algorithms specialized in mobile vector map services, based on previous works. We will show the detail to adapt the approaches on the mobile environment, to display complex spatial objects efficiently on the mobile devices which have restriction on the resources