• Smart Structures and Systems
• /
• v.21 no.1
• /
• pp.99-111
• /
• 2018

Wind induced large bending oscillation amplitudes in tall and slender telecommunication steel towers may lead to precocious fatigue cracks and consequent risk of collapse of these structures, many of them installed in rural areas alongside highways and in highly populated urban areas. Varying stress amplitudes at hot spots may be attenuated by means of passive control mechanical devices installed in the tower. This paper gives an account of both mathematical-numerical model and the technique applied to design and evaluate the performance of a double controller installed in existing towers which is composed by a nonlinear pendulum and a novel type of passive controller described herein as a planar motion disk mounted on shear springs. Results of experimental measurements carried out on two slender tubular steel towers under wind action demonstrate the efficiency of the double controllers in attenuating the towers bending oscillation amplitudes and consequent stress amplitudes extending the towers fatigue life.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.139-142
• /
• 2001

As microeletronics technology continues to progress, there is also a continuous demand on highly integration and miniaturization of systems. For example, it is desirable to package several integrated circuits together in multilayer structure, such as multichip modules, to achieve higher levels of compactness and higher performance. Passive components (i.e., capacitors, resistors, and inductors) are very important for many MCM applications. In addition, the low-temperature co-fired ceramic (LTCC) process has considerable potential for embedding passive components in a small area at a low cost. In this paper, we investigate a method of statistically modeling integrated passive devices from just a small number of test structures. A set of LTCC inductors is fabricated and their scattering parameters (5-parameters) are measured for a range of frequencies from 50MHz to 5GHz. An accurate model for each test structure is obtained by using a building block based modeling methodology and circuit parameter optimization using the HSPICE circuit simulator.

• Proceedings of the KIEE Conference
• /
• 2006.10c
• /
• pp.333-335
• /
• 2006

This paper presents a force-reflecting teleoperation scheme with time delay. In reciprocal systems, to improve the stability and performance of the tleleoperation system, the network provides a wide bandwidth, no congestion. However, as use of Internet increases, congestion situation of network increased and transmission time and packet loss increased accordingly. This can make system unstable at remote control. In this paper, we present a passive control scheme for a force reflecting bilateral teleoperation system via the Internet and we investigated how a varying time delay affects the stability of a teleoperation system. A new approach based on a passive control scheme was designed for the system. The simulation results and the tracking performance of the implemented system are presented in this paper.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.06a
• /
• pp.1204-1209
• /
• 2000

Many analytical and experimental studies on the active suppression of nonlinear panel flutter by using piezoceramic patch have been carried out. However, these active control methods have a few important problems; a large amount of power is required to operate actuators, and additional apparatuses such as sensor systems and controller are needed. In this study passive suppression schemes for nonlinear flutter of composite panel, which is believed to be more robust suppression system than active control in practical operation, are proposed by using piezoelectric inductor-resistor series shunt circuit. Toward the end, a finite element equation of motion for an electromechanically coupled system is proposed using the Hamilton's principle. To achieve the best damping effect, optimal shape and location of the piezoceramic(PZT) patches are determined by using genetic algorithms. The results clearly demonstrate that the passive damping scheme by using piezoelectric shunt circuit can effectively attenuate the flutter.

• 제어로봇시스템학회:학술대회논문집
• /
• 1990.10a
• /
• pp.469-474
• /
• 1990

The implementation of modern guidance law derived from optimal control theory requires accurate current states of target, for example, position, velocity and acceleration etc. But there is no sensors that measure the target states directly. So they are estimated from measurable data. For atmospheric missile engagement, direct application of the modern guidance laws may result In deterioration of Intercept performance because of poor observability associated with angles only-measurements by passive seeker and homing geometry. In this paper, a trajectory modulation method called "adaptive Intermittent maneuvers" is added to the modern guidance law, so the observability is enhanced and, consequently, improved the intercept performance. The estimation algorithm called "modified gain pseudo-measurement filter" is used for tracking filter. It is assumed that the passive seeker measure the angles between line of sight and Inertial frame. The Monte-Carlo simulation for realistic air-to-air Intercept scenario are conducted to demonstrate the effectiveness of intermittent maneuvers.ermittent maneuvers.

• 한국정보통신설비학회:학술대회논문집
• /
• 2006.08a
• /
• pp.11-14
• /
• 2006

This paper reviews the optical link technologies which have been developed for gigabit-per-second wavelength-division-multiplexing passive optical networks (WDM-PONs). Similarly to the 100Mb/s WDM-PON systems which have been deployed for trial services by KT, the most important requirement for 1Gb/s WDM-PON is wavelength independence (colorless feature) of its ONU/ONTs, which makes possible convenient operation and cost-effective maintenance with minimum inventory cost. Among various methods to implement such colorless feature, four promising candidates for gigabit WDM-PON are analyzed with their own development issues and their expected performances are compared.

• Proceedings of the KIPE Conference
• /
• 1998.10a
• /
• pp.859-864
• /
• 1998

Compact and small size, reliable and failsafe operation and low cost featuring fault current limiter causing the designer to take a close look into the use of passive fault current limiter(FCL) for the protection of power semiconductor devices in power electronic systems. This paper has identified the main parameters responsible for the development of ideal passive magnetic current limiter. The effect of those parameters on the range of operation and the voltage-current characteristics of the magnetic current limiter has been studied using tableau approach. Desirable characteristics are discussed and the simulation results are presented.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.13 no.1
• /
• pp.9-21
• /
• 2010

In this paper, optimum design of distributed detection is considered for a parallel sensor network system consisting of a fusion center and multiple passive sonar nodes. Nonrandom fusion rules are employed as the fusion rules of the sensor network. For the nonrandom fusion rules, it is shown that a threshold rule of each sensor node has uniformly most powerful properties. Optimum threshold for each sensor is investigated that maximizes the probability of detection under a constraint on energy consumption due to false alarms. It is also investigated through numerical experiments how signal strength, false alarm probability, and the distance between three sensor nodes affect the system detection performances.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.348-348
• /
• 2008

In recent, the concept of system-on-package (SOP) for highly integrated multifunctional systems has been paid attention to for the miniaturization and high frequency of electronic devices. In order to realize SOP, co-integration of passive devices, such as capacitors, resistors and inductors, and active devices should be achieved. If ceramic thick films can be grown at room temperature, we expect to be able to overcome many problems in conventional fabrication processes. So, we focused on the aerosol deposition method (ADM) as room temperature fabrication technology. ADM is a novel ceramic coating method based on the Room Temperature Impact Consolidation (RTIC) phenomena. This method has a wide range potential for fabrication of co-integration of passive and active devices. In this paper, I will present the future potential of ADM introducing various ceramic dielectric thick films for the integration of electronic ceramics.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.55 no.1
• /
• pp.29-36
• /
• 2006

The interest for harmonic problems has been increasing due to the increment of nonlinear loads. The loads such as DC power system, personal computers, UPS system, inverters and converters operate as harmonic current sources. In this paper, a new type of the passive filter, Hybrid Harmonic Filter (HHF) is suggested to mitigate harmonic problems in power systems. The HHF is developed for reducing harmonic current, especially on the system that includes 6-pulse bridge rectifiers. Also, it is expected to prevent the overheating of transformers and feeders due to overcurrent and to correct the power factor.