• Transactions on Electrical and Electronic Materials
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• v.3 no.4
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• pp.21-26
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• 2002

Color correction methods of chromaticity coordinates using Color Matching Function (CMF) were studied to develop a device-independent portable-type urine analyzer. The reflection spectra were measured for the degrees of 10 test items of the urine reagent strip (urine strip) to develop a portable-type urine analyzer. A computer simulation was performed to quantitatively distinguish the color reactions of the urine system, by using the spectral power distribution of Light Emitting Diode(LED), the reflection of a urine strip, and spectral sensitivity of a photodiode. To develop a device-independent system, chromaticity coordinates were modified to reduce the color deviations in the urine strip, by using the temperature compensation of LED and the color transformation by CMF. The experimental values obtained by developed urine system exhibited the accuracy above 95% for all color samples.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.239-244
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• 2015

Recently, Impulse radars using UWB technologies are widely use for measuring distance, or for transmitting uncompressed high resolution videos. However, since the UWB band spans over octave bands, it is not easy to design such a system. Wide band impedance matching is required for antennas and other RF area. In this study, we designed and fabricated sinuous antenna for 3~6 GHz octave band application. We also designed and attached a dielectric lens to improved the directional gain of the antenna. The gain of the antenna was 6~10 dBi. The dielectric lens attached sinuous antenna was used to transmit HD video data. The maximum reach distance was 90 meter with 10mW power.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.11
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• pp.1215-1220
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• 2014

In this paper, a local oscillator for X-band radar system is designed and fabricated with GaAs MESFET. GaAs MESFET is good for microwave oscillators because of very low noise figure and high electron mobility. Oscillator design methods in this paper are used the characteristic of negative resistance of active component and impedance matching technique without RF resonator. So, oscillator is designed in compact size because space of RF resonator is reduced and can be applied MMIC technique. Designed oscillator has characteristic of the output power of 2.30 dBm and center frequency of 10.545GHz.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1632-1638
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• 2008

This paper presents a method to design CPW (coplanar waveguide) balanced amplifiers using the existing CPW wilkinson balun. In order to realize the required power dividing/combining structure for balanced amplifiers, the CPP wilkinson balun is adopted. The proposed CPW balanced amplifier has much better matching performances than the CPW single-ended amplifier. The measured frequency bands, where the input and output reflection coefficients are less than -10dB, are $1.2{\sim}2.75GHz$ and $1{\sim}3.25GHz$, respectively, while the CPW single-ended amplifier has severely bad ones.

• Journal of Powder Materials
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• v.14 no.4
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• pp.261-264
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• 2007

The electromagnetic wave (EM) absorption properties of various particle size have been investigated in a sheet-type absorber using the $Fe_{73}Si_{16}B_{7}Nb_{3}Cu_{1}$ alloy powder. With decreasing the average particle size, the complex permeability (${\mu}_{r}$) and permittivity (${\varepsilon}_{r}$) increased and the matching frequency is shifted toward lower frequency. The fabricated EM wave absorbers showed permeability $2{\sim}6$, permittivity $17{\sim}23$ for a $-325{\sim}+400$ mesh sample, and the calculated power absorption was as high as 80% in the frequency range over 2 GHz.

• Korean Journal of Optics and Photonics
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• v.9 no.4
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• pp.236-239
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• 1998

We constructed a frequency doubler with a frequency-stabilized Nd:YAG Laser, a nonlinear crystal KTP, and an external resonant cavity. Using type II phase-making method and a resonant cavity, one usually have a serious problem that the second harmonic conversion efficiency is decreased greatly, for under usual circumstances ordinary ray and extraorninary ray cannot be resonated in a cavity simultaneously. With the change of temperature and incident angle of KTP, we found an optimized condition for the phase-matching and double-resonance. As a result we produced 26 mW of green light with 318 mW of fundamental laser power from a cw Nd:YAG laser.

• Journal of Korea Society of Industrial Information Systems
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• v.4 no.1
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• pp.102-109
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• 1999

In this paper, Electromagnetic scattering problem by a perfectly conducting strip grating with 2 dielectric layer on a grounded plane by incidence of a electric wave is analyzed by applying the PMM (Point Matching Method) known as a simple procedure. The scattered electromagnetic fields are expanded in a series of Floquet mode functions. The boundary conditions are applied to obtain the unknown field coefficients and the conducting boundary condition is used for the relationship between the tangential electric field and the electric current density on the strip When the incident angle is normal incidence the minimum value of the geometrically normalized reflected power according as relative permittivity is increased it should be noted that the value of the strip width gets moved toward high value. Them most energy by a normal incident wave is scattered in direction of the other angles except normal incident angle.

• Nuclear Engineering and Technology
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• v.49 no.5
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• pp.1071-1078
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• 2017

A buncher is one of the main pieces of equipment in the medium energy beam transport line (MEBT) for China accelerator driven sub-critical system (C-ADS) Injector II. To focus the beam longitudinally and match the beam for the acceptance of the superconducting linac section, two room temperature quarter wave resonator (QWR) bunchers with frequency of 162.5 MHz have been designed as parts of the MEBT. According to the beam transmission matching of the MEBT and the geometric parameters requirements of bunchers, the unique mechanical structure and the main processing technology of buncher cavities and their couplers and tuners are described in this paper. The fabrication of bunchers and their parts have been completed and tested at high power, the test results agree well with the design requirements. These bunchers work well for about two years in Institute of Modern Physics, Chinese Academy of Sciences.

• Journal of the Optical Society of Korea
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• v.15 no.1
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• pp.38-43
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• 2011

We have developed a simple model of a bright-room contrast ratio (BRCR) measurement system for plasma display panels (PDPs) adopting a contrast enhancement film (CEF) by using an illumination design tool. Only four model parameters were used, namely, total ambient illumination power delivered by fluorescent lamps, a panel scattering rate, illuminance of PDP white patterns, and the absorption coefficient of a color adjusting film. These parameters were determined by simple optical measurements and matching simulations. The proposed model was employed to predict the BRCR values of four different CEF samples, and the simulated ones were found to be in agreement with measured ones within about 10% relative-error.

• Journal of information and communication convergence engineering
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• v.16 no.4
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• pp.252-257
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• 2018

A wideband double radiator circular disc annular monopole antenna is proposed is this work. The radiators are etched on the surfaces of two Taconic TLY-5 substrates with a circular hole cut out of each of the radiators initially at the centers of the radiators with subsequent downward displacement of the holes. The antenna is designed with a two-step feeding transformer system for impedance matching between the input power source supplied by a $50-{\Omega}$ SMA connector and the monopole radiators. The transformer system improves the bandwidth performance at higher frequencies. The proposed antenna achieves a wideband having the capability of working between 0.645 and 18.775 GHz, corresponding to a -10 dB bandwidth of 186.7% with gain ranging from 0.95 to 8.26 dBi. In comparison to other metal disc planar monopole antennas, the proposed antenna has a small total size width due to the size of the ground plane, which has a diameter 100 mm. The frequency range of the antenna provides applications in global positioning systems, mobile communications, ultra-wideband short distance communications, and wireless computer networks.