• Nuclear Engineering and Technology
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• v.51 no.4
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• pp.954-962
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• 2019

It is well known that the variance of tally is biased in a Monte Carlo calculation based on the power iteration method. Several studies have been conducted to estimate the real variance. Among them, the batch method, which was proposed by Gelbard and Prael, has been utilized actively in many Monte Carlo codes because the method is straightforward, and it is easy to implement the method in the codes. However, there is a problem when utilizing the batch method because the estimated variance varies depending on batch size. Often, the appropriate batch size is not realized before the completion of several Monte Carlo calculations. This study recognizes this shortcoming and addresses it by permitting selection of an appropriate batch size.

• Korean Journal of Materials Research
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• v.3 no.5
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• pp.514-520
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• 1993

In this paper the cure cycle of carbon fiber/phenolic resin was investigated by the Taguchi Method in an experimental design. Experiments were systematically performed using $L_{18}(2^1 \times 3_7)$ orthorgonal array table of the experimental design. In the experimental design, eight compression molding parameters (heating rate, pressing temperature, pressing rate, molding pressure, curing temperature, dwell time at curing temperature, cooling rate and degassing) were considered and the effects of the parameters on the flexural strength and the apparent porosity of carbon fiber/phenolic composites were investigated. The analysis of variance for the experimental results indicated that molding pressure and curing temperature are the most significant parmeters in the flexural strength and the apparent porosity of carbon fiber/phenolic resin composites, respectively.

• Journal of Korea Multimedia Society
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• v.22 no.12
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• pp.1376-1384
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• 2019

The cosmetic and behavioral aspects of aging have become increasingly evident over the years. Physical aging in people can easily be observed on their face, posture, voice, and gait. In contrast, bone aging only becomes apparent once significant bone degeneration manifests through degenerative bone diseases. Therefore, a more accurate and timely assessment of bone aging is needed so that the determinants and its mechanisms can be more effectively identified and ultimately optimized. This study proposed a deep learning approach to assess the bone age of an adult using whole-body bone scintigraphy. The proposed approach uses multiple inputs deep neural network architectures using a loss function, called mean-variance loss. The data set was collected from Chonnam National University Hwasun Hospital. The experiment results show the effectiveness of the proposed method with a mean absolute error of 3.40 years.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.101.1-101.1
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• 2014

The fluctuation of VLBI visibility phase can be occurred, predominantly caused by the irregular distribution and motion of water vapor in the atmosphere at high frequencies (>1GHz). This radio-seeing effect shows up on filled-aperture telescopes as an anomalous refraction (AR). This can be shown as if the antenna pointing-offset increases, in other words the apparent displacement of radio sources from its nominal position happens. We carried out the single-dish observations on KVN sites in order to check the effect of AR from 2010 to 2014. Orion KL, U Her, and R Leo were observed with 1second sampling time at 22.235GHz and 43.122GHz simultaneously. Each source was observed with the tracking mode for 30 minutes per a source. We analyzed the structure function, power spectrum and Allan variance of the data according to a day and a night, a season and observatories. Finally, we can infer that the AR effect depends on the atmospheric environment, especially tropospheric turbulence.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.9
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• pp.1410-1419
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• 1989

In this paper, we present a new synthetic high coding method which gives high image compression ratio. Given an image, only its low-pass component is transmitted by DCT coding` the high-pass component is not transmitted but synthesized using edge sharpening on the reconstructed low-pass image at the receiver. For the DCT coding which is used to encode the low-pass image, we used an improved version of Cox's variance estimator. Also, introduced are new image quality measures called GSNR and EPR which emphasize perceptual aspects of image quality. Experimental results show that the performance of the proposed synthetic high coding is better in various quality measures than that of Cox's adaptive transform coding. Also, it yields acceptable image quality with neither apparent block effect nor visible granular noise even at high compression ratio of about 30:1.

• Communications for Statistical Applications and Methods
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• v.13 no.1
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• pp.151-165
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• 2006

It is important to estimate the true misclassification rate of a given classifier when an independent set of test data is not available. Cross-validation and bootstrap are two possible approaches in this case. In related literature bootstrap estimators of the true misclassification rate were asserted to have better performance for small samples than cross-validation estimators. We compare the two estimators empirically when the classification rule is so adaptive to training data that its apparent misclassification rate is close to zero. We confirm that bootstrap estimators have better performance for small samples because of small variance, and we have found a new fact that their bias tends to be significant even for moderate to large samples, in which case cross-validation estimators have better performance with less computation.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.2
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• pp.215-222
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• 2015

The objective of this research was to evaluate the growth performance, the apparent ileal digestibility of nitrogen and energy, the retention of nutrients and the apparent metabolizable energy corrected to zero nitrogen retention (AMEn) in broiler chickens supplemented with increasing doses of a worm leachate (WL) as a source of humic substances (HS) in the drinking water. In Exp. 1, 140 male broilers were penned individually and assigned to four WL levels (0%, 10%, 20%, and 30%) mixed in the drinking water from 21 to 49 days of age. Water was offered in plastic bottles tied to the cage. In Exp. 2, 600 male broilers from 21 to 49 days of age housed in floor pens were assigned to three levels of WL (0%, 10%, and 20%) mixed in the drinking water. The WL was mixed with tap water in plastic containers connected by plastic tubing to bell drinkers. The results of both experiments were subjected to analysis of variance and polynomial contrasts. In Exp. 1, the daily water consumption was similar among treatments but the consumption of humic, fulvic, and total humic acids increased linearly (p<0.01) as the WL increased in the drinking water. The feed conversion (p<0.01) and the ileal digestibility of energy, the excretion of dry matter and energy, the retention of dry matter, ash and nitrogen and the AMEn showed quadratic responses (p<0.05) relative to the WL levels in drinking water. In Exp. 2, the increasing level of WL in the drinking water had quadratic effects on the final body weight, daily weight gain and feed conversion ratio (p<0.05). The addition of WL as a source of HS in the drinking water had beneficial effects on the growth performance, ileal digestibility of energy, the retention of nutrients as well on the AMEn in broiler chickens; the best results were observed when the WL was mixed at levels of 20% to 30% in the drinking water.

• Investigative Magnetic Resonance Imaging
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• v.22 no.2
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• pp.79-85
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• 2018

Purpose: To determine the impact of pseudoglandular formation on apparent diffusion coefficient (ADC) values of hepatocellular carcinoma (HCC) in diffusion-weighted imaging (DWI), and to validate the results using histopathological grades. Materials and Methods: We assessed 182 HCCs surgically resected from 169 consecutive patients. Each type of tumor pseudoglandular formation was categorized into "non-," "mixed-," or "pure-," based on official histopathology reports. The ADC for each tumor was independently measured, using the largest region of interest on the ADC map. Data were assessed using the analysis of variance test, with Bonferroni correction for post hoc analysis to stratify the relationship of ADCs with pseudoglandular formation, followed by subgroup analysis according to the histopathological tumor grades. Results: The mean ADC was significantly higher in pure pseudoglandular lesions (n = 5, $1.29{\pm}0.08{\times}10^{-3}mm^2/s$) than in non-pseudoglandular lesions (n = 132, $1.08{\pm}0.17{\times}10^{-3}mm^2/s$; P = 0.003) or mixed-pseudoglandular lesions (n = 45, $1.16{\pm}0.24{\times}10^{-3}mm^2/s$; P = 0.034). The ADC values and pseudoglandular formation were significantly correlated in moderately differentiated HCCs (n = 103; r = 0.307, P = 0.007), while well- (n = 19) and poorly-differentiated HCCs (n = 60) did not show significant correlation (r = 0.105 and 0.068, respectively; P = 0.600 and 0.685, respectively). Conclusion: The degree of pseudoglandular formation could be one of the determinants of ADC in DWI of HCCs-especially moderately differentiated HCCs-while its influence does not appear to be significant in well- or poorly differentiated HCCs.

• Korean Journal of Radiology
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• v.22 no.5
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• pp.759-769
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• 2021

Objective: To evaluate the application of laplacian-regularized mean apparent propagator (MAPL)-MRI to brain glioma-induced corticospinal tract (CST) injury. Materials and Methods: This study included 20 patients with glioma adjacent to the CST pathway who had undergone structural and diffusion MRI. The entire CSTs of the affected and healthy sides were reconstructed, and the peritumoral CSTs were manually segmented. The morphological characteristics of the CST (track number, average length, volume, displacement of the affected CST) were examined and the diffusion parameter values, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD), mean squared displacement (MSD), q-space inverse variance (QIV), return-to-origin probability (RTOP), return-to-axis probabilities (RTAP), and return-to-plane probabilities (RTPP) along the entire and peritumoral CSTs, were calculated. The entire and peritumoral CST characteristics of the affected and healthy sides as well as those relative CST characteristics of the patients with motor weakness and normal motor function were compared. Results: The track number, volume, MD, RD, MSD, QIV, RTAP, RTOP, and RTPP of the entire and peritumoral CSTs changed significantly for the affected side, whereas the AD and FA changed significantly only in the peritumoral CST (p < 0.05). In patients with motor weakness, the relative MSD of the entire CST, QIV of the entire and peritumoral CSTs, and the AD, MD, RD of the peritumoral CST were significantly higher, whereas the RTPP of the entire and peritumoral CSTs and the RTOP of the peritumoral CST were significantly lower than those in patients with normal motor function (p < 0.05 for all). In contrast, no significant changes were found in the CST morphological characteristics, FA, or RTAP (p > 0.05 for all). Conclusion: MAPL-MRI is an effective approach for evaluating microstructural changes after CST injury. Its sensitivity may improve when using the peritumoral CST features.

• Korean Journal of Environment and Ecology
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• v.28 no.3
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• pp.273-280
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• 2014

This study examined whether Dybowski's brown frogs(Rana dybowskii) in noisy highway roadsides had different mating calls from those in natural sites. We selected four study sites: two rice paddy sites in Youngdong Highway roadside and two nearby natural counterparts. Frog calls were recorded between 18:30 and 20:00 on February 24, February 27, and March 14, 2014. Frog calls in the natural sites had fundamental frequency approximately at 700 Hz with two to four apparent harmonics, while frog calls in the highway sites had higher fundamental frequency with up to seven apparent harmonics. Analysis of variance (ANOVA) shows that a roadside site that are directly exposed to highway noise had statistically higher frog calling frequency than other study sites. However, the higher calling frequency was not found in another roadside site that differed in elevation from the highway and was buffered by forests. These results indicate that male frogs in a noisy highway roadside called females with a higher pitch and more apparent harmonics to avoid being masked by highway noise. These results also suggest that there is a threshold noise level that interrupts frog's mating behavior and it is needed to maintain highway roadside noise to this threshold level.