• Journal of Information Processing Systems
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• 제2권3호
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• pp.159-162
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• 2006

Wireless LANs are becoming more widespread because of the rapid advance of wireless technologies and mobile computers. In this paper, we present the design and implementation of a system to help mobile users to select the most competent AP. By monitoring the network traffic of APs within the local LAN in real time, this system offers the mobile user the network utilizations, locations, and signal strengths of APs online. Based on the information, the user can select a competent AP with a high wireless bandwidth. Finally, we verified the accuracy of monitoring and calculating with regard to the utilizations of APs through real experiments.

• 전기학회논문지P
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• 제58권3호
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• pp.334-338
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• 2009

In this paper, We report the miniaturization of superconducting microwave power dividers based on lumped element equivalent circuits. To do this, we analyzed a conventional branch-type power divider by using an ABCD matrix under even and odd mode excitation. Then, we calculated each lumped element impedance throughout this analysis of a transmission line matrix. Also we simulated our equivalent circuits made of lumped elements by using a full wave analysis, em Sonnet. Our deign of microwave power divider based on simulated results was fabricated on high-$T_c$ superconducting thin films deposited on MgO substrate. Experimental results were reported in terms of bandwidth, center frequency, and phase difference between $S_{21}$ and $S_{31}$. We confirm that our design will be useful in the future microwave power systum.

• 센서학회지
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• 제17권4호
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• pp.261-266
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• 2008

In this paper, we present thermal characteristics of high-temperature measurement sensor using fiber Bragg grating(FBG), including peak reflectivity, FWHM bandwidth and various normalized refractive index change along temperature variation. The temperature stability of FBG temperature sensor can be changed by varying the refractive index change and grating length. The proposed FBG temperature sensor can measure up to about $600^{\circ}C$ and 1000 hours of heating time.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.280-285
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• 2008

The helmholtz resonator with the perforated neck has demerits that the absorption performance is not so outstanding in an anti-resonance frequency and high frequency bandwidth. In order to overcome these problems, in the paper, a resonator combined with porous material is proposed. The absorption performances of resonators are measured by two-microphone method and estimated by transfer matrix method. The experimentally measured values of normal absorption coefficients agree well with the corresponding values from the transfer matrix method. Because of the porous material, it is shown that the absorption performance have been significantly improved in the anti-resonance frequency and high frequency bandwidth.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.592-598
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• 1992

For a high bandwidth, accurate end of arm motion control with good disturbance rejection, the, Momentum Management Approach to Motion control (MMAM) is proposed. The MMAM is a kind of position control technique that uses inertial forces, applied at or near the end of arm to achieve, high bandwidth and accuracy in movement and in the face of force disturbances. To prove the concept of MMAM, the, end point, control of a flexible manipulator is considered. For this purpose, a flexible beam is mounted on the x-y table, and the MMAM actuator is attached on the top of the flexible beam. A mathematical model is developed for the flexible, beam being controlled by the, MMAM actuator and slide base DC motor. A system identification method is applied to estimate some system parameters in the, model which can not be determined because of the complexity of the mechanism. For the end point, control of the. flexible beam, the, optimal linear output feedback control is introduced.

• 전기학회논문지
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• 제56권12호
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• pp.2257-2261
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• 2007

A new CMOS transresistance amplifier for low-voltage analog integrated circuit design applications is presented. The proposed transresistance amplifier circuit based on common-source and negative feedback topology is compared with other recent reported transresistance amplifier. The proposed transresistance amplifier achieves high transresistance gain, gain-bandwidth with the same input/output impedance and the minimum supply voltage $2V_{DSAT}+V_T$. Hspice simulation using 1.8V TSMC $0.18{\mu}m$ CMOS technology was performed and achieved $59dB{\Omega}$ transresistance gain which is above the maximum about $18dB{\Omega}$ compared to transresistance gain of the reported circuit.

• 한국소음진동공학회논문집
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• 제19권6호
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• pp.628-633
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• 2009

The helmholtz resonator with the perforated neck has demerits that the absorption performance is not so outstanding in an anti-resonance frequency and high frequency bandwidth. In order to overcome these problems, in the paper, a resonator combined with porous material is proposed. The absorption performances of resonators are measured by two-microphone method and estimated by transfer matrix method. The experimentally measured values of normal absorption coefficients agree well with the corresponding values from the transfer matrix method. Because of the porous material, it is shown that the absorption performance have been significantly improved in the anti-resonance frequency and high frequency bandwidth.

• Journal of Communications and Networks
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• 제4권4호
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• pp.292-301
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• 2002

Wireless LAN technology is complementary to 3G systems and could be used to provide high bandwidth hotspot coverage, for example in railway stations and offices, in order to provide the high bandwidth video and broadband services such as those emerging on DSL fixed access. The IST Projects BRAIN and MIND have investigated a number of key technical enablers for such a system beyond 3G. These include scenarios and business models, design of an all-IP access network, consideration of ad hoc network extensions, enhancing Wireless LAN efficiency and compatibility with IP and, finally, terminal middleware and signalling for rapid adaptations to network QoS changes.

• 제어로봇시스템학회논문지
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• 제7권2호
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• pp.160-167
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• 2001

This paper presents control and evaluation of a new haptic device with a 6-DOF parallel mechanism for interfacing with virtual reality. This haptic device has low inertial, high bandwidth compactness, and high output force capability mainly due to of base-fixed motors. It has also wider orientation workspace mainly due to a RRR type spherical joint. A control method is presented with gravity compensation and with force feedback by an F/T sensor to compensate for the effects of unmodeled dynamics such as friction and inertia. Also, dynamic performance has been evaluated by experiments. for force characteristics such as maximum applicable force, static-friction force, minimum controllable force, and force bandwidth Virtual wall simulation with the developed haptic device has been demonstrated.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.65-66
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• 2005

This paper presents an adaptive satellite communication systems to adapt channel environment. High performance coding and modulation techniques are applied to poor channel condition, otherwise, bandwidth efficient coding and modulation techniques are applied to good channel condition to obtain high transmission rate.