• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.10
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• pp.851-860
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• 2013

To overcome a scarcity of radio resources to mobile broadband service, the usage of TV white space gains much attraction around the world. This paper carries out an interference analysis either by performing realistic experiments or by executing statistical Monte-Carlo simulation to exploit interference probability. The results obtained from experiments are compared to those from simulations in order to clarify the coexistence of utilization of TV band devices (TVBD) in indoor circumstances. Along the execution of our experiment in the presence of DTV receiver, we apply to a variety of transmission parameters proposed in FCC for TVBD. According to experimental and simulation works, the allowable transmission powers of TVBD systems are exploited for the plausible which are coexist on the first as well as the second adjacent frequency bands. Throughout results, it can conclude that TVBD systems can be coexisted via achieving proper transmission powers depending on the locations of themselves without showing harmful interference to DTV reception.

• JSTS:Journal of Semiconductor Technology and Science
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• v.9 no.4
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• pp.192-197
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• 2009

This paper presents the design and measurement of a 2.4/5.2-GHz dual band VCO with a balanced frequency doubler in $0.18\;{\mu}m$ CMOS process. The topology of a 2.4 GHz VCO is a cross-coupled VCO with a LC tank and the frequency of the VCO is doubled by a frequency balanced doubler for a 5.2 GHz VCO. The gate bias matching network for class B operation in the balanced doubler is adopted to obtain as much power at 2nd harmonic output as possible. The average output powers of the 2.4 GHz and 5.2 GHz VCOs are -12 dBm and -13 dBm, respectively, the doubled VCO has fundamental harmonic suppression of -25 dB. The measured phase noises at 5 MHz frequency offset are -123 dBc /Hz from 2.6 GHz and -118 dBc /Hz from 5.1 GHz. The total size of the dual band VCO is $1.0\;mm{\times}0.9\;mm$ including pads.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.3
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• pp.564-571
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• 2009

In this paper, we propose out-of -band collaborative spectrum sensing scheme in the cognitive radio (CR) base station operated by the multiple frequency channels. Also this paper presents the signal detection results for ATSC digital TV signal as an incumbent signal and derives signal detection probability and false alarm probability for the out-of-band collaborative spectrum sensing scheme in frequency selective Rayleigh fading channel. Numerical results demonstrate that the sensing performance is improved by the out-of-band collaborative spectrum sensing in the case that the incumbent signal powers measured by the CR terminals of the multiple frequency channels are almost similar.

• Journal of the Ergonomics Society of Korea
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• v.29 no.2
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• pp.189-196
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• 2010

The study is to find relative EEG power spectrum and pattern of coherence discriminating attentive and inattentive hand movements. Eight undergraduate students aged from 20 to 27 who had not hand disability participated in this study. Participants were asked to perform visuo-motor task. EEG was measured at C3 in 10~20 international system and four areas orthogonally directed 2.5cm away from C3. Significant result discriminating movement and rest was found through coherence analysis between movement areas or movement area and non-movement area, but was individually different. Because it was anticipated that major factors caused by the differences among individuals were attributed to the attention of the subjects, relative power of alpha and beta bands was identified. As a result, significant relative powers of alpha and beta bands were found in a group of high coherence level, but were not found in a group of low level. Next, participants were divided into two groups according to relative powers of alpha and beta bands. The comparison between two groups was performed. As a result, the coherence of the alpha band in the attentive group was greater than that of the inattentive group. It was found that the coherence of the beta band in the inattentive group was happening. Therefore, individual differences of coherence were influenced by attention. The significant coherence patterns that could discriminate attentive movement and inattentive movement were found.

• Korean Journal of Materials Research
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• v.16 no.6
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• pp.360-366
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• 2006

A series of ZnO thin films were grown by radio-frequency (RF) magnetron sputtering with various RF powers on $SiO_2/Si$(100) substrates at $500^{\circ}C$. Thicknesses of the investigated ZnO films were fixed to about 250nm by changing the growth time based on the changes of growth rates with RF powers. All the ZnO thin films were grown with <0001> preferred orientation. Average grain sizes of about 250nm-thick ZnO films evaluated by FE-SEM, AFM, and TEM were increased by decreasing the RF power. Structural properties addressed by FWHM values of XRD (0002) omega rocking curves and their intensities were better for the smaller grain sized ZnO films grown with high RF powers, which implies small values of tilt for smaller grain sized ZnO films. However, optical properties addressed by intensities of band edge emissions from room temperature and low temperature photoluminescence were better for the larger grain sized ZnO films with low RF power, which implies grain boundaries acted as nonradiation recombination centers.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.3
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• pp.45-54
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• 2014

In this paper, We have designed and fabricated 20 InP Gunn diodes using a current limiting epitaxial structure by MINT's optimized fabrication processes. We have also packaged the fabricated InP Gunn diodes using our optimized packaging method, and then designed and fabricated a W-band waveguide FTO to measure characteristics of the packaged InP Gunn diodes. The packaged InP Gunn diode have a ceramic ring, a Au plated stud and a lid, and a Maltese cross. The fabricated InP Gunn diodes have good RF characteristics such as high output powers (11.8~17 dBm) and limiting low currents (less than 400 mA) between 92.9 and 94.78 GHz.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.9
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• pp.54-58
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• 2011

In this paper a dual-band Class-E power amplifier using Composite Right-/Left-Handed transmission lines and PIN diode is proposed. Dual-band operation is achieved by the frequency offset and nonlinear phase slope of CRLH TL for the matching network of power amplifiers. The proposed power amplifier has been realized by using in the input and the output matching network for high power added efficiency. PIN diode has been used to obtain the dual-band of power amplifier. The measured results show that output powers of 42.17 dBm and 41.43 dBm were obtained at 800 MHz and 1900 MHz, respectively. At this frequency, we have obtained the power-added efficiency(PAE) of 67.84 % and 65.31 % in two operation frequencies, respectively.

• Korean Journal of Remote Sensing
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• v.22 no.1
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• pp.25-40
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• 2006

Synthetic aperture radar (SAR) from satellites provides the opportunity to regularly incorporate microwave information into forest classification. Radar backscatter can improve classification accuracy, and SAR interferometry could provide improved thematic information through the use of coherence. This research examined the potential of using multi-temporal JERS-l SAR (L band) backscatter information and interferometry in distinguishing forest classes of mountainous areas in the Northeastern U.S. for future forest mapping and monitoring. Raw image data from a pair of images were processed to produce coherence and backscatter data. To improve the geometric characteristics of both the coherence and the backscatter images, this study used the interferometric techniques. It was necessary to radiometrically correct radar backscatter to account for the effect of topography. This study developed a simplified method of radiometric correction for SAR imagery over the hilly terrain, and compared the forest-type discriminatory powers of the radar backscatter, the multi-temporal backscatter, the coherence, and the backscatter combined with the coherence. Statistical analysis showed that the method of radiometric correction has a substantial potential in separating forest types, and the coherence produced from an interferometric pair of images also showed a potential for distinguishing forest classes even though heavily forested conditions and long time separation of the images had limitations in the ability to get a high quality coherence. The method of combining the backscatter images from two different dates and the coherence in a multivariate approach in identifying forest types showed some potential. However, multi-temporal analysis of the backscatter was inconclusive because leaves were not the primary scatterers of a forest canopy at the L-band wavelengths. Further research in forest classification is suggested using diverse band width SAR imagery and fusing with other imagery source.

• Journal of electromagnetic engineering and science
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• v.7 no.4
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• pp.147-153
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• 2007

This paper represents an analog predistortion linearizer for the high power amplifier with low memory effect. The high power amplifier is implemented using a 90-W peak envelope power(PEP) LDMOSFET at 2.14-GHz and an envelope short matching topology is applied at the active ports to minimize the memory effect. The analog predistortion circuit comprises the fundamental path and the cuber and quintic generating circuits, whose amplitudes and phases can be controlled independently. The predistortion circuit is tested for two-tone and wide-band code division multiple access(WCDMA) 4FA signals. For the WCDMA signal, the adjacent channel leakage ratios(ACLRs) at 5 MHz offset are improved by 12.4 dB at average output powers of 36 dBm and 42 dBm.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.3
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• pp.245-250
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• 1999

The effects of an antipsychotic, chlorpromazine, on the electroencephalogram (EEG) were observed while rats were awake but immobile. The time course and the dose-dependency of the EEG changes were examined. The method of the power spectrum analysis was used to examine the EEG changes by the drug. The bands were divided into delta $(1{\sim}3.5\;Hz),$ theta $(3.5{\sim}8\;Hz),$ alpha $(8{\sim}13\;Hz),$ beta1 $(13{\sim}21\;Hz),$ beta2 $(21{\sim}30\;Hz)$ and gamma $(30{\sim}50\;Hz).$ In rats, the low dose of chlropromazine (1 mg/kg, i.p.) produced a significant increase in the power of the beta1 band. The higher doses (5, 10 mg/kg, i.p.) produced a significant increase in the power of the delta, theta, alpha and beta1 bands, and the decrease in the power of the gamma band. The powers of the bands changed dose-dependently. Then, the authors discussed whether the EEG effects produced by a drug are associated with the accompanying behavioral changes specifically.