• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.20 no.3
• /
• pp.484-490
• /
• 2016

Full-duplex communication can enhance wireless capacity by enabling simultaneous transmission and reception of the signals on the same frequency spectrum. Such a benefit, however, is only achieved when strong self-interference is well canceled below a sufficient level. To achieve this goal, there have been several approaches for cancellation, each of which is combined with digital-domain cancellation for a higher gain. In this paper, we implement two self-interference cancellation techniques and integrate them with a software defined radio-based wireless communication testbed. Two cancellation techniques (antenna cancellation and noise subtraction) are implemented and the cancellation gain is measured via real experiments. The results show that the gain of the antenna placement technique highly depends on the placement of a receiving antenna and the highest gain is achieved at the expected point, and we show that combining the noise subtraction circuit with the antenna placement further improves the cancellation gain.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2007.06a
• /
• pp.758-761
• /
• 2007

Digital signal processing technique is applied in wide fields such as speech processing, image processing and spectrum analysis. Therefore, in order to do frequency selective operation digital filter is used in stead of analog filter and sharp filter characteristics can be implemented. Since finite impulse response (FIR) digital filter as nonrecursive type represents linear phase response characteristics and is always stable and is used in fields regarding wave information importantly such as data transmission. And due to frequency characteristics, in order to remove the Gibbs phenomenon generating around a discontinuous point, filter is designed through window function method. Therefore, in this paper to improve performance of FIR digital filter, a modified window function was applied. And the proposed method was compared with conventional methods using peak side-lobe and transition properties in simulations.

• Journal of the Optical Society of Korea
• /
• v.15 no.4
• /
• pp.386-393
• /
• 2011

In this study, we report an effective k-domain linearization method with a pre-calibrated indexed look-up table. The method minimizes k-domain nonlinear characteristics of a swept source optical coherence tomography (SS-OCT) system by using two arrays, a sample position shift index and an intensity compensation array. Two arrays are generated from an interference pattern acquired by connecting a Fabry-Perot interferometer (FPI) and an optical spectrum analyzer (OSA) to the system. At real time imaging, the sample position is modified by location movement and intensity compensation with two arrays for linearity of wavenumber. As a result of evaluating point spread functions (PSFs), the signal to noise ratio (SNR) is increased by 9.7 dB. When applied to infrared (IR) sensing card imaging, the SNR is increased by 1.29 dB and the contrast noise ratio (CNR) value is increased by 1.44. The time required for the linearization and intensity compensation is 30 ms for a multi thread method using a central processing unit (CPU) compared to 0.8 ms for compute unified device architecture (CUDA) processing using a graphics processing unit (GPU). We verified that our linearization method is appropriate for applying real time imaging of SS-OCT.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.14 no.2
• /
• pp.184-189
• /
• 2004

In this paper, we realized a system that receives the dynamic images of finger languages, which is the method of intention transmission of the hearing disabled person, using the white and black CCD camera, and that recognizes the images and converts them to the editable text document. We use the afterimage to draw a sharp line between indistinct images and clear images from a series of inputted images, and get the character alphabet from the away of continuous images and output the accomplished character to the word editor by applying the automata theory. After the system removes the varied wrist part from the data of clean image, it gets the controid point of hand by the maximum circular movement method and recognizes the hand that is necessary to analyze the finger languages by applying the circular pattern vector algorithm. The system abstracts the characteristic vectors of the hand using the distance spectrum from the center of the hand and it compares the characteristic vector of inputted pattern from the standard pattern by applying the fuzzy inference and recognizes the movement of finger languages.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
• /
• v.29 no.2
• /
• pp.80-85
• /
• 2018

Objectives: We aimed to assess the test-retest reliability, internal consistency, and validity of the Korean version of the Quantitative Checklist for Autism in Toddlers (Q-CHAT). Methods: The Korean version of the Q-CHAT and the Korean version of the Child Behavior Checklist (CBCL) 1.5-5 were completed by parents of 24 toddlers and preschoolers with autism spectrum disorder (ASD) and 80 unselected toddlers and preschoolers. Parents of the ASD group also completed the Social Communication Questionnaire (SCQ), and Childhood Autism Rating Scale (CARS) scores were obtained from medical records. Results: The ASD group scored higher on the Q-CHAT than the unselected group. The Cronbach's alpha coefficient of the Q-CHAT was 0.658, and test-retest reliability was calculated to be 0.836. The estimated area under the curve was 0.793. The total scores of the Q-CHAT in the ASD group demonstrated significant positive correlations with findings regarding pervasive development problems in the CBCL, SCQ, and CARS. A total score of 33.5 may be a useful cutoff point to use when identifying toddlers at risk of ASD. Conclusion: The Korean version of the Q-CHAT has good reliability and validity and can be used as a screening tool in order to identify toddlers and preschool children at risk of ASD.

• Nuclear Engineering and Technology
• /
• v.44 no.1
• /
• pp.53-60
• /
• 2012

The aim of this study was to explore the spatial and energy resolutions of a PET scanner that we have recently developed. The scanner, which consists of six detector modules with 1-layer LGSO crystals, has a hexagonal configuration with a faceto- face distance of 86.4 mm between two opposite PET modules; such properties facilitate the imaging of small animals. A $^{22}Na$ point source was employed to estimate horizontal and vertical spatial resolutions. To assess the energy resolution, a uniform $^{18}F$ cylindrical phantom was scanned. A software-based spectrum analysis of list-mode data was used to assign a local energy window centered on the photopeak position for every single crystal. For the image reconstruction, an ML-EM algorithm was used. The spatial resolutions at the center of the scanner were 0.99 mm in the horizontal direction and 1.13 mm in the vertical direction. The energy resolution averaged over each PMT ranged from 13.3%-14.3%, which gave an average value of 13.8%. These results show that this simple system is promising for small animal imaging with excellent spatial and energy resolutions.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.11 no.7
• /
• pp.3370-3392
• /
• 2017

Next Generation Beyond 4G/5G systems will rely on the deployment of small cells over conventional macrocells for achieving high spectral efficiency and improved coverage performance, especially for indoor and hotspot environments. In such heterogeneous networks, the expected performance gains can only be derived with the use of efficient interference coordination schemes, such as Fractional Frequency Reuse (FFR), which is very attractive for its simplicity and effectiveness. In this work, femtocells are deployed according to a spatial Poisson Point Process (PPP) over hexagonally shaped, 6-sector macro base stations (MeNBs) in an uncoordinated manner, operating in hybrid mode. A newly introduced intermediary region prevents cross-tier, cross-boundary interference and improves user equipment (UE) performance at the boundary of cell center and cell edge. With tools of stochastic geometry, an analytical framework for the signal-to-interference-plus-noise-ratio (SINR) distribution is developed to evaluate the performance of all UEs in different spatial locations, with consideration to both co-tier and cross-tier interference. Using the SINR distribution framework, average network throughput per tier is derived together with a newly proposed harmonic mean, which ensures fairness in resource allocation amongst all UEs. Finally, the FFR network parameters are optimized for maximizing average network throughput, and the harmonic mean using a fair resource assignment constraint. Numerical results verify the proposed analytical framework, and provide insights into design trade-offs between maximizing throughput and user fairness by appropriately adjusting the spatial partitioning thresholds, the spectrum allocation factor, and the femtocell density.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.46 no.5
• /
• pp.401-406
• /
• 2001

The applicability of non-destructive near infrared reflectance spectroscopic (NIRS) method was tested to determine the protein and oil contents of intact soybean [Glycine max (L.) Merr.] seeds. A total of 198 soybean calibration samples and 101 validation samples were used for NIRS equation development and validation, respectively. In the developed non-destructive NIRS equation for analysis of protein and oil contents, the most accurate equation was obtained at 2, 8, 6, 1(2nd derivative, 8 nm gap, 6 points smoothing, and 1 point second smoothing) and 2, 1, 20, 10 math treatment conditions with Standard Normal Variate and Detrend (SNVD) scatter correction method and entire spectrum (400-2500 nm) by using Modified Partial Least Squares (MPLS) regression, respectively. Validation of these non-destructive NIRS equations showed very low bias (protein: 0.060%, oil: -0.017%) and standard error of prediction (SEP, protein: 0.568 %, oil : 0.451 %) as well as high coefficient of determination ($R^2$, protein: 0.927, oil: 0.906). Therefore, these non-destructive NIRS equations can be applicable and reliable for determination of protein and oil content of intact soybean seeds, and non-destructive NIRS method could be used as a mass screening technique for selection of high protein and oil soybean in breeding programs.

• Cartoon and Animation Studies
• /
• s.43
• /
• pp.231-254
• /
• 2016

The graphic novel is seemed different from comics in two aspects, visual expression and narrative value. However, they are ambiguous standards, so it needs to research each works of graphic novel deeper. Then this paper studied both of visual expression and narrative in Craig Thompson's "Habibi" that has been recognized a fine graphic novel. As the research about how the modes of expression that an American author choose on purpose to represent an arab female are related with narrative, it will get the point of narrative strategy that graphic novel can have potentially. So It studied new modes of expression as focusing on imagination of arab letters and woman growth-narrative by using Gayle Rubin's 'traffic in women' theory, and how it was related with modes of expression in graphic novel. This paper will be helpful for broadening spectrum of expression in graphic novel as comics media having own narrative form and studying graphic narrative potential.

• Journal of Astronomy and Space Sciences
• /
• v.14 no.2
• /
• pp.286-296
• /
• 1997

Magnetohydrodynamic wave phenomena have been investigated in the deep plasmasphere by the electric field measurements in the EXOS-D(Akebono) satellite. EXOS-D has highly eccentric orbits(the perigee: 274km, the apogee: 10,500km), which allows relatively long observational time interval near the apogee region compared to other satellites which pass by the same region with less eccentric orbits. Case studies are performed on one month data of October in 1989 where the apogee is located near the equator and the magnetic local time is about 9:00-12:00 a.m. in the dayside plasmasphere. The observational region ranges from L=2 to L=3 and the magnetic latitude is restricted to less than 30 degrees. The power spectrum is examined for each 128 point series of 8-sec averaged data through a FFT, which covers f = 0~62.3 mHz frequency bands. The results are well consistent with field line resonances (FLRs) and cavity modes in the plasmasphere.