• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.12
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• pp.1102-1109
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• 2013

Blind interference alignment (BIA) scheme has demonstrated a way of interference alignment (IA) without channel state information at transmitter (CSIT). While it shows superior performance in high signal-to-noise ratio (SNR) regime stemming from the maximal degrees of freedom (DoF) gain, BIA scheme achieves inferior sum-rate performance in low SNR regime. This paper proposes a dual-mode transmission strategy which switches between single user (SU) SISO with receive mode selection and the BIA scheme depending upon the range of SNR. First, we derive a closed-form achievable rate for each transmission-mode. Secondly, we propose a low-complex transmission-mode selection algorithm.

• Journal of Advanced Navigation Technology
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• v.13 no.1
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• pp.48-53
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• 2009

The CMOS RF front-end for Global Positioning System(GPS)are implemented in 1P8M CMOS $0.13{\mu}m$ process. The LNAs consist of LNA1 with high gain and low NF, and LNA2 with low gain and high IIP3 for supporting operation with active and passive antenna. the measured performances of both LNAs are 16.4/13.8 dB gain, 1.4/1.68 dB NF, and -8/-4.4 dBm IIP3 with 3.2/2 mA form 1.2 V supply, respectively. The quadrature downconversion mixer is followed by transimpedance amplifier with gain controllability from 27.5 to 41 dB. The front-end performances in LNA1 mode are 39.8 dB conversion gain, 2.2 dB NF, and -33.4 dBm IIP3 with 6.6 mW power consumption.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.6
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• pp.19-24
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• 2004

A novel fast parallel NTGST is proposed for high resolution computer vision inspection of the BLUs in a LCD production line. The conventional computation- intensive NTGST algorithm is modified and its C codes are optimized into fast NTGST to be adapted to the SIMD parallel architecture. And then, the input inspection image is partitioned and allocated to each of the P processors in multi-threaded implementation, and the NTGST is executed on SIMD architecture of N data items simultaneously in each thread. Thus, the proposed inspection system can achieve the speedup of O(NP). Experiments using Dual-Pentium III processor with its MMX and extended MMX SIMD technology show that the proposed parallel NTGST is about Sp=8 times faster than the conventional NTGST, which shows the scalability of the proposed system implementation for the fast, high resolution computer vision inspection of the various sized BLUs in LCD production lines.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.8 s.338
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• pp.1-6
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• 2005

A dual-level low voltage differential signalling (DLVDS) circuit is proposed aiming at reducing transmission lines for LCD driver IC. In the proposed circuit, we apply a couple of primitive data to DLVDS circuit as inputs. The transmitter converts two inputs to two kinds of fully differential level signals. In this circuit, two transmission lines are sufficient to transfer two primitive inputs while keeping the LVDS feature. The receiver recovers The original input data through a level decoding circuit. We fabricated the proposed circuit using $0.25\mu m$ CMOS technology. The resultant circuit shows 1-Gbps/2-line data rate and 35-mW power consumption at 2.5V supply voltage, respectively.

• Journal of IKEEE
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• v.13 no.3
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• pp.72-79
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• 2009

This paper describes a compact microstrip active antenna with dual polarization. The antenna, receiving both a left-hand circularly polarized wave and a right-hand circularly polarized wave, has a function of polarization diversity. A square-shaped empty room is located on the inside of the microstrip radiator so that the size has been reduced. And slots are added around feeding point to improve input matching. Also, amplifier and switching circuitry are placed at the empty room to increase antenna gain and to select one of the circular polarizations, respectively. The proposed antenna has been applied to GPS(global positioning system). The measurement results show that it has 10dB-impedance bandwidth, 3dB axial bandwidth of about 50MHz, 3dB beamwidth of 90degree, and gain of 13dBi, respectively, for RHCP. Also, it has 3dB axial bandwidth of about 50MHz, 3dB beamwidth of 84 degree, and gain of 12dBi, respectively, for LHCP.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.12 s.115
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• pp.1224-1230
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• 2006

In this paper, for spatial multiplexing with limited feedback, a precoding scheme is proposed based on the joint use of minimal instantaneous feedback and long-term feedback of a small number of bits, wherein the long-term feedback is used to convey a selected preceding matrix within a precodercodebook consisting of a number of unitary matrices, and the active column vectors of the selected unitary matrix are conveyed to the transmitter using instantaneous feedback. Focusing on the case of dual multi-input multi-output(MIMO) systems, precoder codebook design for maximizing the average throughput of a spatial multiplexing system with a zero-forcing(ZF) receiver is proposed. It is shown that the proposed scheme provides a considerable throughput enhancement over multi-mode antenna selection and multi-mode basis selection only with the additional long-yterm feedback of a small number of bits. For example, the throughput increases by 11.5 % than antenna selection and 5.1% than basis selection, respectively, when SNR=20 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.8
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• pp.927-932
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• 2008

We propose a novel $4{\times}4$ Hadamard matrix feed network for a $4{\times}1$ array antenna to form a dual beam. If each element of the array is excited following the elements in a row of the Hadamard matrix, a two-lobed antenna beam can be obtained. The angle between the two lobes can be controlled. The Hadamard matrix feed network consists of four $90^{\circ}$ hybrids, a crossover and four $90^{\circ}$ phase shifters. The array, including the Hadamard matrix feed network, was fabricated on a microstip structure. The measured beam directions of the two lobes are $0^{\circ}$, ${\pm}15^{\circ}$, ${\pm}33^{\circ}$, ${\pm}45^{\circ}$ depending on the choice of the input port of the feed network.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.1
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• pp.44-54
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• 2001

In this paper, a novel test method is proposed to detect the hard and soft fault in analog circuits. The proposed test method makes use of the offset voltage, which is one of the op-amps characteristics. During the test mode, CUT is modified to unit gain op-amps with feedback loop. When the input of the op-amp is grounded, a good circuit has a small offset voltage, but a faulty circuit has a large offset voltage. Faults in the op-amp which cause the offset voltage exceeding predefined range of tolerance can be detected. In the proposed method, no test vector is required to be applied. Therefore the test vector generation problem is eliminated and the test time and cost is reduced. In this note, the validity of the proposed test method has been verified through the example of the dual slope A/D converter. The HSPICE simulations results affirm that the presented method assures a high fault coverage.

• Journal of Power Electronics
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• v.19 no.6
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• pp.1366-1379
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• 2019

High-gain DC/DC converters have become one of the key technologies for the grid-connected operation of new energy power generation, and its research provides a significant impetus for the rapid development of new energy power generation. Inspired by the transformer effect and the ripple-suppressed ability of a coupled inductor, a double-coupled inductor high gain DC/DC converter with a ripple absorption circuit is proposed in this paper. By integrating the diode-capacitor voltage multiplying unit into the quadratic Boost converter and assembling the independent inductor into the magnetic core of structure coupled inductors, the adjustable range of the voltage gain can be effectively extended and the limit on duty ratio can be avoided. In addition, the volume of the magnetic element can be reduced. Very small ripples of input current can be obtained by the ripple absorption circuit, which is composed of an auxiliary inductor and a capacitor. The leakage inductance loss can be recovered to the load in a switching period, and the switching-off voltage spikes caused by leakage inductance can be suppressed by absorption in the diode-capacitor voltage multiplying unit. On the basis of the theoretical analysis, the feasibility of the proposed converter is verified by test results obtained by simulations and an experimental prototype.

• Journal of Industrial Convergence
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• v.19 no.6
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• pp.145-153
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• 2021

This study empirically verified whether there is a dual mediating effect of individual optimistic bias and information security intention in the relationship between information security attitude and information security behavior of social welfare college students. The subjects were 295 college students majoring in social welfare. Spss Process macro was used for analysis. As a result. first there was a significant positive correlation between the variables. Second in the relationship between information security attitude and information security behavior, individual optimistic bias and information security intent each had a simple mediating effect. Third when an individual's optimistic bias and information security intent were simultaneously input, each had a simple mediating effect. Fourth there was a double mediating effect between individual optimistic bias and information security intent. This study provided basic data for the expansion of information security model and information security education of social welfare students.