• Journal of electromagnetic engineering and science
• /
• v.15 no.4
• /
• pp.206-212
• /
• 2015

This paper introduces new wideband antenna-filter-antenna (AFA) uniform arrays that can be utilized as frequency selective surfaces (FSS) with low loss and sharp roll-off response, which are highly desirable characteristics for millimeter wave applications. The design adopts a simple 3-layer single polarization structure consisting of two patch antennas and a resonator. Both simulations and measurements are used to characterize the performances of the proposed design. Overall results show 18.5% 10-dB bandwidth. For the targeted band the insertion loss is less than 0.2 dB. Possible applications include quasi-optical amps, grid mixers and radomes for aircraft radar antennas.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.33A no.6
• /
• pp.42-51
• /
• 1996

Performance analysis of FH/CPFSK system with liiter-discriminator detection and integrate-dump post-detection filtering under the thermal noise and the partial-band noise jamming on the rayleigh fading channel have been analyzed. The thermal noise and partial-band noise jamming, rayleigh fading, intersymbol interference for all eight of the possible adjacent bit data patterns, and FM noise click for evaluating systems have been considered. Also optimum parameters to improve performance of FH/CPFSK system have been obtained and validities for AMPS and CDMA system of land-mobile-communication system through computer simulation have been proved.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.34D no.12
• /
• pp.39-45
• /
• 1997

This study presents the first experimental data for the impact of hot-carrier degradtion on the performance of CMOS folded-cascode op-amps. A folded-cascode op-amp which has an NMOS input pair has been designed and fabricated using a 0.8.mu.m single-poly, double-metal CMOS process. After high voltage stress, the degradtion of perfomrance parameters such as open-metal CMOS process. After high voltage stress, the degradation of performance parameters such as open-loop voltage gain, unity-gain frequency and phase margin has been analized and physically explaniend in terms of hot carrier degradation.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2000.11a
• /
• pp.111-115
• /
• 2000

In this paper, a prototype electronic ballast for 400W MH lamps is designed and implemented. To remove the phenomenon of acoustic resonance in the lamp being operated at high frequency, a spread spectrum method is employed on the ballast. Half-bridge resonant inverter, voltage-controlled-oscillator and PFC are used and the current of lamp is controlled with taking into account the voltage of lamp. The ballast is built with analog OP-amps and MOSFETs. The experimental results show the good performance as PF 0.93, ATHD 0.14, Ballast loss 22W at output 400W.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.17 no.3
• /
• pp.65-70
• /
• 2008

Capacitive position sensing with modulation technique is widely used in electrostatic actuator applications. To maximize the electrostatic force and the position-sensing gain, capacitors for driving and capacitors for sensing are shared, i.e, after applying the driving voltage with high-frequency modulating signals using op amps, the position is demodulated from the modulated signal. In high-voltage applications, however, low bandwidth of a high-voltage op amp hinders adding the high-frequency modulating signal to the driving voltage. In this paper, new and very simple driving and sensing method is proposed, in which the pulse-width modulated driving voltage eliminates the need of the high-frequency modulating signal for position sensing. This new algorithm is proved by the simulation results using Matlab/SIMULINK.

• Applied Chemistry for Engineering
• /
• v.23 no.5
• /
• pp.429-432
• /
• 2012

According to the requirement of novel antimicrobial agents for the rapidly increasing emergence of multi-drug resistant pathogenic microbes, a number of researchers have found new antibiotics to overcome this resistance. Among them, antimicrobial peptides (AMPs) are host defense molecules found in a wide variety of invertebrate, plant, and animal species, and are promising to new antimicrobial candidates in pharmatherapeutic fields. Therefore, this review introduces the antimicrobial action of antimicrobial peptide and ongoing development as a pharmetherapeutic agent.

• Progress in Superconductivity and Cryogenics
• /
• v.7 no.2
• /
• pp.44-46
• /
• 2005

A SMES can be a perfect alternative energy storage device to the chemical batteries which are needed by most of the renewable energy supply systems. The chemical battery storage system is so expensive to maintain and causes another environmental problem because they are not recyclable. But, SMES has semi-permanent lifetime and no environmental problems cause it only need coolants which is non flammable, clean and recyclable gas. In order to verify the feasibility of a SMES for the renewable electrical power supply system, electrical characteristics of a test SMES coil with the photovoltaic power system were analyzed in this paper. Simulation results show that we can charge 40 amps of current in test SMES coil using solar power system. The experimental verification will be performed just after development of the peak power tracking system for the solar system.

• The Journal of the Acoustical Society of Korea
• /
• v.17 no.1E
• /
• pp.3-9
• /
• 1998

In this paper, a robust active noise controller is designed to reduce noise in al small cavity. Noise characteristics in the small cavity are nonlinear and we could get its model with considerable modelling errors. The objective of this paper is to minimize the effects of these modelling errors and maximize the noise reduction performance. The solution could be obtained by the H∞ robust control theory. The resulting feedback controller minimizes the H∞ norm of the mixed sensitivity function, which means the effects of uncertainties of the model are suppressed in the sense of stability and the performance is enhanced as a given specification. The designed controller is realized with analog devices such as Op. Amps and experimental results show that the controller reduces noise signal sufficiently.

• Journal of the Korean institute of surface engineering
• /
• v.17 no.3
• /
• pp.73-77
• /
• 1984

The surface residual stresses in 1mm thick nickel electrodeposits obtained from four types of nickel sulphamate baths at 40 to 60$^{\circ}C$ and 5 to 25 amps./$dm^2$ were measured by a X-ray method. An increase in nickel chloride concentration in the bath tends to increase tensile residual stresses in the deposits. Addition of no chloride or little chloride in the baths gave rise to little residual stresses or even compressive stresses in the deposits. The residual stresses in most specimens did not exceed 80 MPa and showed minimum in the specimens obtained at 50$^{\circ}C$.

• ETRI Journal
• /
• v.19 no.3
• /
• pp.83-97
• /
• 1997

The CDMA Mobile System (CMS) has been developed by Electronics and Telecommunications Research Institute (ETRI) and field-tested for commercial service deployment in Korea. The project was started in 1989 and completed in 1995 with the CMS commercial test. During the course of development, there had been active technical cooperation with Qualcomm, Inc. and Korean manufacturers. The CMS adopted the basic CDMA concepts conforming to Korean CDMA system which was derived form IS-95. The CMS functions are allocated to subsystems by considering efficiency and expandability. The CMS consists of mobile stations and the infrastructure which is composed of base stations, mobile exchanges and home location register/authentication center. The commercial field tests performed both in Taejon and Seoul have indicated that the CMS capacity is 10 to 15 times larger than that of AMPS. This paper overviews the development history, system characteristics, architecture and test results.