• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.30-31
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• 2000

400DPI LED array was fabricated by using reactive ion etching(RIE) method. Material of fabricated LED array was used the GaP for green light emitting and had a homojunction structure. Each cells of emitting area in the LED array were defined with RIE etching for electrical isolation between cells. Electrodes were formed on each cells to emit independently. Ohmic contact resistivity was approximate 1.2$\times$10$^{5}$ $\Omega$/$\textrm{cm}^2$ and 1.26$\times$10$^{5}$ $\Omega$/$\textrm{cm}^2$ using isothermal annealing at 38$0^{\circ}C$ and 43$0^{\circ}C$. Emitting intensity of each etmitting cell was 1.65 cd/$m^2$.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.3
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• pp.200-205
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• 2014

In this paper, 5.8GHz band $4{\times}4$ Butler matrix is designed using easily accessible commercial $90^{\circ}$ hybrid coupler and semirigid coaxial cable as a transmission line. This Butler matrix is very flexible to changes of antenna system specification like a frequency band because $90^{\circ}$ hybrid coupler changing is all to do. The result of design is the distance of $2{\times}2$ array antenna element is $\sqrt{2}{\lambda}/4$, the 4 beam directions are diagonal of array antenna and phase shifter is not necessary. The beam width is roughly $25^{\circ}$ narrower because of array antenna geometry and the side lobe is about 10dB higher partially than theoretical beam pattern. But the overall beam pattern is similar with theoretical beam. This Butler matrix can be applied to switching beam antenna of 5.8GHz band Wi-Fi and WAVE system.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.3
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• pp.48-55
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• 2006

This paper describes the antenna based GPS anti-jamming technology called CRPA(Controlled Reception Pattern Antenna), which used $2{\times}2$ array elements. In this system, the main functions are the antenna complex weight control and the GPS digital I/Q VM(Vector Modulator). To update the VM's I/Q complex weights, the PC based DAC(Digital to Analog Converter) module was also used and the two analog output voltages were applied to the $2{\times}2$ array elements to synthesize the null pattern. In the study, we also simulated the $2{\times}2$ GPS array null patterns to compare the null depth with experimental results. The VM was also modified at the frequency of 1.575GHz for the GPS L1 and controlled by the PC based VM software.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.608-611
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• 2000

Large area plasma source becomes important as the substrate size increases. In this work, four inductively coupled plasma(ICP) unit sources are distributed 2${\times}$2 array. E-ICP concept is applied to the 2${\times}$2 array ICP and its effect is examined. Characteristics of the plasma are measured, and photoresist etching is performed with oxygen plasma. Good etching characteristic in terms of etching rate and uniformity can be obtained with E-ICP.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.1022-1032
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• 1999

The radiation characteristics of a microstrip circularly-polarized aperture-patch $8\times8$ array antenna are investigated at X-band. The radiator consists of a truncated square aperture on the ground plane with an inclined rectangular patch inside, and it is coupled by a microstrip line on the opposite side of the ground. The element spacing of the array was chosen as $0.8\lambda_0$so as to minimize the mutual coupling and maximize the gain. A corporate feed network was employed to distribute the power to each element through four Wilkinson and two T-junction dividers. Measurement results for the $8\times8$ array at 10 GHz showed a directivity of 26.3 dBi, a gain of 22.2 dBi, an axial ratio of 2.97 dB, and a side lobe level of -12.7dB. It was observed that when the array size increases, the directivity increases while the efficiency decreases.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.715-718
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• 2002

TX/RX dual microstrip 1$\times$8 sub-array antennas are designed, fabricated, and measured for a wideband array antennas in communications. They have a Right Handed Circular Polarization (RHCP) for TX from 7.9 to 8.4 GHz and Left Handed Circular Polarization (LHCP) for RX from 7.25 to 7.75 GHz. Two stacked patches are used for a wideband characteristics and cornertruncated square patches are adopted for a circular polarization. To enhance bandwidth characteristics of a circular polarization, 1$\times$2 sequential rotation arrays are applied. From the measured results, 1$\times$8 microstrip sub-array antennas have a good agreement with those of the simulation. Therefore the sub-array antennas are applicable to satellite communication antennas, active phased array antennas, and radiators in other antennas.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.2
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• pp.164-171
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• 2014

Transmit(Tx)/Receive(Rx) dual band operation microstrip array for X-band satellite communications are designed, fabricated, and measured in this paper. The microstrip array antenna has Right Handed Circular Polarization(RHCP) for Tx band and Left Hand Circular Polarization(LHCP) for Rx band. Two stacked patches are used for wideband characteristics and corner-truncated square patches are adopted for a circular polarization. To enhance bandwidth characteristics of a circular polarization, $2{\times}2$ sequential rotation array are applied. From the measured result, $8{\times}12$ microstrip array antennas have a good agreement with those of the simulation. Therefore the array antennas are applicable to military satellite communication antennas.

• The Korean Journal of Applied Statistics
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• v.17 no.3
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• pp.499-505
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• 2004

The Pareto diagram analysis of the experimental data by the two level orthogonal arrays has been used widely in practice since it is a graphical, quick and easy method to analyze experimental results, which does not use the analysis of variance to screen significant effects. For the analysis of the experimental data by $L_{18}(2 \times 3^7)$ orthogonal array, Park(1996) proposed Pareto ANOVA in which the size of effects is defined by the mean squares of effects and the Pareto principle is used. In this paper, a new approach of the Pareto diagram analysis of the experimental data by $L_{18}(2 \times 3^7)$ orthogonal array is proposed. The main idea is to partition the size of three level effects by that of linear and quadratic orthogonal contrasts of those effects.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.4
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• pp.628-635
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• 1999

At center frequency of 11.85 GHz, wideband left-handed circularly polarized microstrip array antenna is designed with the method of sequential ratation based on $2\times2$ radiation elements($0^{\circ}$, $45^{\circ}$, $90^{\circ}$, $135^{\circ}$ phase delay). Its return loss, axial ratio bandwidth, radration pattern, and gain are compared with those adopting sequential rotation based on $1\times2$ radiation elements($0^{\circ}$, $90^{\circ}$, $180^{\circ}$, $270^{\circ}$phase delay). The $8\times8$ array is manufactured and measured. The results show that 10 dB return loss bandwidth is 10.51~12.74GHz(18.82%) which is 1.57 times wider than the case using $1\times2$ sequential rotation method, 3 dB axial ratio bandwidth is 11.43~12.5 GHz(9.03%) which is 1.25 times as wide as that using $1\times2$ sequential rotation method and the antennal gain is 25.4 dB. The results of mesurements are almost similar to those of simulation.

• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.144-151
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• 1994

We designed and fabricated a $2{\times}4$ symmetric self electro-optic effect device array using GaAs/ AIo.04 G$\DeltaR$), and optical bistability loop width ($\Delta$). The average values of the elements of the $2{\times}4$ S-SEED array were CR~13.1, R~24%, and $\Delta$~91%. It was found that the AFP cavity structure enhances the self-biased optical bistability in ESQW-SEED under no external bias. That is due to the decreased intrisic region thickness in AFP-SEED structures, and which increases the built-in electric fields. The zero-biased S-SEED showed CR of ~4.7, R~9%, and $\Delta$~22%.X>~22%.