• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.11
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• pp.31-37
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• 1998

Magnitude/phase controlling circuit which is composed of attenuator and phase shifter make phase/gain cross-coupling, so too much tuning time is needed to find optimum operation point. In this paper, vector attenuator which control magnitude and phase of input signals is proposed. Vector attenuator in past ignores phase variation characteristics of attenuator, but vector attenuator of this paper compensates phase variation characteristics of attenuator. This vector attenuator consists of 0$^{\circ}$/180$^{\circ}$ phase shifter and low phase shifting attenuator and so forth. A 0$^{\circ}$/180$^{\circ}$ phase shifter has 0$^{\circ}$/179.9$^{\circ}$ phase shifting characteristics at a center frequency 881 MHz and a low phase shifting attenuator has an attenuation of 25dB, within the limit of 3.6$^{\circ}$ phase shift and less than -20dB reflection characteristics at both input and output ports. The designed vector attenuator shows that cartesian coordinate plane of output signal space can be represented correctly.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.10
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• pp.26-36
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• 2000

In this paper, we design the nonoverlapping multicarrier modulation (MCM) system for high rate paging system and evaluate the Performance by computer simulation. In conventional paging system, FSK was usually used, but we select QAM for high bandwidth efficiency. Transmitter structure adopts that of 4-16QAM of the iDEN$\^$TM/ and receiver consists of symbol timing recovery, carrier recovery and automatic gain control. In addition, pilot symbol aided modulation (PSAM) which can overcome the simulcast fading channel is considered and we also propose the optimum pilot symbol pattern. Finally, we show the performance of the overall 4-16QAM system by computer simulation.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.9 no.4
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• pp.182-193
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• 1997

The interaction of monochromatic incident waves with a horizontal flexible membrane is investigated in the context of two-dimensional linear hydro-elastic theory. First, analytic diffraction and radiation solutions for a submerged impermeable horizontal membrane are obtained. Second, the theoretical prediction was compared with a series of experiments conducted in a two-dimensional wave tank at Texas A & M University. The measured reflection and transmission coefficients reasonably follow the trend of predicted values. Using the developed computer program, the performance of surface-mounted or submerged horizontal membrane wave barriers is tested with various system parameters and wave characteristics. It is found that the properly designed horizontal flexible membrane can be an effective wave barrier.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.3
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• pp.288-296
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• 1992

This paper describes an improved 2D QPS(quadrature polar separable) filter design and its applications to texture processing. The filter kernel pair consists of the product of a radial weighting function based on the finite PSS (prolate spheroidal sequences) and an exponential at tenuation function for the orientational angle. It is quadrature and polar separable in the frequency domain. It is near optimal in the energy loss because we let the orientational angle function approximate the radial weighting function. The filter frequency characteristics is easy to control as it depends only upon the design specifications such as the bandwidth, the directional angle, the attenuation constant, and the shift constant of the central frequency. Some applications of the filter in texture processing, such as the generation of the texture image, the estimation of orientation angles, and the segmentations for the synthetic texture image, are considered. The result shows that the filter with the wide bandwidth can be used for the generation of discrimination of the strong orientational textures and the segmentation results are good.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1797-1805
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• 2012

In this paper, Power LED(Light Emitting Diodes) is studied to driver as a new lighting system in the spotlight, replacing a large existing lighting system with fluorescent and incandescent lighting. To take advantage a variety of DC power as the boost DC-DC converter design specifications through the inductor L and capacitor C through PSPICE to calculate the best estimate of the value. Converter's switching frequency is 50[kHz], the first Duty Rate was made to increase gradually depending on the value of the detection were, 10[%] in the output voltage. As a result, the simulated Boost Power LED driver characteristics is in comparison with the design specifications, 5[%] or less as the error was approximated. So, when input 15[V] were offered, a stable output 24[V] were obtained, and Dimming Control through the adjustment of brightness and current consumption were obtained to possible result.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.7
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• pp.56-65
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• 1999

In this paper, a pixelated binary phase grating to generate $5{\times}5$ spots in designed using simple Genetic Algorithm(sGA) composed of selection, crossover, and mutation operators, and it can be applied for the optical interconnection. So as to adapt that GA is a robust and efficient schema, a chromosome is coded as a binary integer of length $32{\times}32$, the ranking method for decreasing the stochastic sampling error is performed, and a single-point crossover having $16{\times}16$ block size is used. A designed grating when the probabillty of mutation is 0.001, the probability of crossover is 0.75 and the population size is 300 has a 74.7[%] high diffraction efficiency and a $1.73{\times}10^{-1}$ uniformity quantitatively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1A
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• pp.37-52
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• 2004

In this paper, Multistage Adaptive Partial PIC eliminating effectively the multiple access and multipath interference for DS-CDMA based W-CDMA uplink system is designed and its performance is evaluated with computer simulation. By adaptively controlling the slope of the soft limiter with received signals, the efficiency of the soft limiter can be maximized and the better performance is obtained by solving error floor problem using further precise generation of interference signal. As a result, The proposed Multistage Adaptive Partial PIC with simple optimizing method for time-variant channel showed optimum performance at fewer stages. Besides fewer stages, the interference cancellation at the output of the rake receiver considerably reduced system complexity. The Multistage Adaptive Partial PIC with precise generation and efficient cancellation of interference signal can solve error eoor problem, resulted from initial false detection and improve system performance of high data rate system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.7
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• pp.1-11
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• 2002

This paper proposes that an efficient routing entry sending method between routing controller FE. based on this method, we organize IP VPN support method based on MPLS network and design MPLS-VPN service control module, MPLS-VPN processing, VPN group configuration and LSP setup processing. We evaluate the performance about the VPN based on proposed MPLS, at the result of evaluation. We figure out that based on proposed IPC method, lost packets number reduces and delay increases more slowly in case of VPN based on MPLS comparing with the VPN based on ATM which has rapid delay increasement. Therefore we confirm that the VPN based on MPLS has high speed of packet processing and high utilization of buffers through the performance evaluation.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.6 s.312
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• pp.16-26
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• 2006

In this paper, we propose a 3D shape restoration system which measures height and surface shape of transparent ITO glass and delivers errors in focal length and incident angle of laser beam to femto-second laser micromachining. The proposed system is composed of a line scan laser, a high resolution camera, a linear motion guide synchronized to image capturing, and a control station. Also, we define the sensitivity indices that represent a relation between measurement error and a position of a camera and scan laser, and utilize it for optimum design. The results of the proposed system are compared with results of SPM(Scanning Probe Microscope) and prove the usefulness of the system.

• Composites Research
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• v.13 no.6
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• pp.23-29
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• 2000

The internal residual stresses within the multilayered structure with sharp interface induced by the difference in thermal expansion coefficient between the materials of adjacent layers often provide the source of failure such as delamination of interfaces etc. Recent development of the multilayered structure with functionally graded interface would be the solution to prevent this kind of failure. However a systematic thermo-mechanical analysis is needed for the customized structural design of multilayered structure. In this study, theoretical model for the thermo-mechanical analysis is developed for multilayered structures of the $Al-SiC_p$ functionally graded composite for electronic packaging. The evolution of curvature and internal stresses in response to temperature variations is presented for the different combinations of geometry. The resultant analytical solutions are used for the optimal design of the multilayered structures with functionally graded interface as well as with sharp interface.