• Journal of the Institute of Convergence Signal Processing
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• v.12 no.4
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• pp.322-332
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• 2011

In this paper, we introduce the 1st performance evaluation of VLBI Correlation Subsystem (VCS) main product, which is core system of Korea-Japan Joint VLBI Correlator (KJJVC). The main goal of the 1st performance evaluation of VCS main product is that the perfection of overall system will be enhanced after checking the unsolved part by performing the experiments towards various test items at the manufacturer before installation of field. The functional test was performed by including the overflow problem occurred in the FFT re-quantization module due to the insufficient of effective bit at the VCS trial product in this performance test of VCS main product. Through the performance test for VCS main product in the factory, the problem such as FFT re-quantization discovered at performance test of VCS trial product in 2008 was clearly solved and the important functions such as delay tracking, daly compensation, and frequency bining were added in this VCS main product. We also confirmed that the predicted correlation results (fringe) was obtained in the correlation test by using real astronomical observed data(wideband/narrow band).

• Current Photovoltaic Research
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• v.4 no.4
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• pp.150-154
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• 2016

Mg and In co-doped ZnO (MIZO) thin films with transparent conducting characteristics were successfully prepared on glass substrates by RF magnetron sputtering technique. The Influence of different substrate temperature (from RT to $400^{\circ}C$) on the structural, morphological, electrical, and optical properties of MIZO thin films were investigated. The MIZO thin film prepared at the substrate temperature of $350^{\circ}C$ showed the best electrical characteristics in terms of the carrier concentration ($4.24{\times}10^{20}cm^{-3}$), charge carrier mobility ($5.01cm^2V^{-1}S^{-1}$), and a minimum resistivity ($1.24{\times}10^{-4}{\Omega}{\cdot}cm$). The average transmission of MIZO thin films in the visible range was over 80% and the absorption edges of MIZO thin films were very sharp. The bandgap energy of MIZO thin films becomes wider from 3.44 eV to 3.6 eV as the substrate temperature increased from RT to $350^{\circ}C$. However, Band gap energy of MIZO thin film was narrow at substrate temperature of $400^{\circ}C$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.3
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• pp.255-262
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• 1997

To estimate the total dry matter(TDM) of rice plant by non-destructive method, spectral reflectance from rice plant canopy was measured by using the spectroradiometer (LI-1800, LICOR Inc.) with one week interval during the rice growing season at Suwon paddy field in 1993. Two medium late maturing rices, Daechung-byeo Ilpum-byeo, and one early maturing variety, Jinbu-byeo, were cultured to observe TDM, then they were compared with those estimated by vegetation index together. Vegetation index determined by the reflectance of visible against near infrared wavelength showed high correlation with TDM. Vegetation index derived from narrow band(10nm interval) ratio, R910/R460, has the highest correlation coefficient with TDM. TDM estimated from R910/R460 from transplanting to heading stage corresponded well to measured values (Y=21.2428X-212.734 ; $R^2$=0.87). But another vegetation index, NIR(720~1,100nm) /Red(600~700nm) showed higher correlation with TDM than NIR(720~1,100nm) /Blue(400~500nm) did from heading stage to maturity.

• Journal of KIISE
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• v.43 no.8
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• pp.869-877
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• 2016

In this paper, we propose an automated segmentation method of femoral cartilage in knee MR images using multi-atlas-based locally-weighted voting. The proposed method involves two steps. First, to utilize the shape information to show that the femoral cartilage is attached to a femur, the femur is segmented via volume and object-based locally-weighted voting and narrow-band region growing. Second, the object-based affine transformation of the femur is applied to the registration of femoral cartilage, and the femoral cartilage is segmented via multi-atlas shape-based locally-weighted voting. To evaluate the performance of the proposed method, we compared the segmentation results of majority voting method, intensity-based locally-weighted voting method, and the proposed method with manual segmentation results defined by expert. In our experimental results, the newly proposed method avoids a leakage into the neighboring regions having similar intensity of femoral cartilage, and shows improved segmentation accuracy.

• Journal of the Institute of Convergence Signal Processing
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• v.1 no.1
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• pp.23-31
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• 2000

Iterative curve evolution techniques are powerful methods for image segmentation. Classical methods proposed curve evolutions which guarantee close contours at convergence and, combined with the level set method, they easily handled curve topology changes. In this paper, we present a new geometric active contour model based on level set methods introduced by Osher & Sethian for detection of object boundaries or shape and we adopt anisotropic diffusion filtering method for removing noise from original image. Classical methods allow only one-way curve evolutions : shrinking or expanding of the curve. Thus, the initial curve must encircle all the objects to be segmented or several curves must be used, each one totally inside one object. But our method allows a two-way curve evolution : parts of the curve evolve in the outward direction while others evolve in the inward direction. It offers much more freedom in the initial curve position than with a classical geodesic search method. Our algorithm performs accurate and precise segmentations from noisy images with complex objects(jncluding sharp angles, deep concavities or holes), Besides it easily handled curve topology changes. In order to minimize the processing time, we use the narrow band method which allows us to perform calculations in the neighborhood of the contour and not in the whole image.

• Journal of The Korean Astronomical Society
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• v.37 no.4
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• pp.285-288
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• 2004

Near-infrared imaging photometry supplemented by optical spectroscopy and narrow-band imaging of the H II region Sh 2-128 and its environment are presented. This region contains a developed H II region and the neighboring compact H II region S 128N associated with a pair of water maser sources. Midway between these, the core of a CO cloud is located. The principal ionizing source of Sh 2-128 is an 07 star close to its center. A new spectroscopic distance of 9.4 kpc is derived, very similar to the kinematic distance to the nebula. This implies a galactocentric distance of 13.5 kpc and z = 550 pc. The region is optically thin with abundances close to those predicted by galactocentric gradients. The $JHK_s$ images show that S 128N contains several infrared point sources and nebular emission knots with large near-infrared excesses. One of the three red Ks knots coincides with the compact H II region. A few of the infrared-excess objects are close to known mid- and far-infrared emission peaks. Star counts in J and $K_s$ show the presence of a small cluster of B-type stars, mainly associated with S 128N. The $JHK_s$ photometric properties together with the characteristics of the other objects in the vicinity suggest that Sh 2-128 and S 128N constitute a single complex formed from the same molecular cloud, with ages ${\~}10^6$ and < $3 {\times} 10^5$ years respectively. No molecular hydrogen emission was detected at 2.12 ${\mu}m$. The origin of this remote star forming region is an open problem.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1A
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• pp.156-166
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• 2000

In discrete multi-tone (DMT)-based very high bit-rate digital subscriber line (VDSL) systems, the ingressed RFI (Radio Frequency Interference) accompanied by transmitted signal at the receiver is known to cause the spectralleakage by the finite-point FFT, resulting in significant performance degradation.0 this paper, we propose a RFIcancellation technique which can compensate the ingressed RFI efficiently, especially for a high data-rate VDSLsystem. The proposed technique compensates the performance degradation of e VDSL system due to RFI byusing a time-domain RFI canceller whose coefficients are obtained from the estimated center frequency of RFI inthe frequency domain under the assumption that the ingressed RFI is a narrow-band signal compared to VDSLsampling frequency. The proposed technique requires no training symbol and convergence period, and worksproperly even when spectral shape of the ingressed RFI is unknown or arbitrary. Feasibility of the proposedtechnique is demonstrated via a computer simulation by comparing its performance with the performance of theprevious RFI cancellation technique.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.2
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• pp.134-139
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• 2004

A clock recovery circuit for a 40 Gb/s optical receiver has been designed and implemented. The clock recovery circuit consists of pre-amplifiers, a nonlinear circuit with diodes, a bandpass filter and a clock amplifier. Before implementing the 40 Gb/s clock recovery circuit, a 10 Gb/s clock recovery circuit has been successfully implemented and tested. With the 40 Gb/s clock recovery circuit, when a 40 Gb/s signal of -10 dBm was applied to the input of the circuit, the 40 GHz clock was recovered with the -20 dBm output power after passing through the nonlinear circuit. The output signal from the nonlinear circuit passes through a narrow-band filter, and then amplified. The implemented clock recovery circuit is planned to be used for the input of a phase locked loop to further stabilize the recovered clock signal and to reduce the clock jitter.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.12
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• pp.1391-1401
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• 2007

This paper proposed a novel broadband printed monopole antenna for PCS/IMT-2000/WLAN terminals. Frequency characteristics are optimized with various design parameters. Two Z-shaped patchs were utilized in order to improve the characteristics of a printed monopole antenna which usually has a narrow bandwidth. The bandwidth of the realized antenna is $1.590{\sim}2.614$ GHz(48.43 %) below the return loss of -10 dB which contain the required bandwidth of PCS/IMT-2000/WLAN band. The simulated and measured values of 1 g and 10 g averaged peak SAR on human head caused by the proposed antenna on folder-type phone were analyzed and discussed. As a result, the measured 1 g peak SAR value is 0.794 W/kg and 10 g peak SAR value is 0.368 W/kg at 1.8 GHz. The results are smaller than the reference SAR limit values that are respectively 1.6 W/kg and 2 W/kg on 1 g and 10 g averaged SAR values.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.4
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• pp.703-715
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• 2017

In this paper, we analyze the channel characteristics of the long distance air-ground wideband common data link and we propose a mathematical method to analyze the effect of narrowband and wideband interference of air-ground channel on the received signal of wideband data link. In this paper, we analyze the reception performance according to the communication distance using the proposed performance analysis method, and found out that the communication distance is limited by the narrowband and wideband interference of ground reflection wave. As a result of the performance analysis of the method of controlling the receiving antenna upward, not only the narrow band but also the wideband interference is effectively reduced, so that the communication distance is increased even in the existing wideband data link not including the equalizer.