• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3C
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• pp.216-225
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• 2007

This paper presents bit splitting methods to apply multilevel modulation to iterative codes such as turbo code, low density parity check code and turbo product code. Log-likelihood ratio method splits multilevel symbols to bits using the received in-phase and quadrature component based on Gaussian approximation. However it is too complicate to calculate and implement hardware due to exponential and log calculation. therefore this paper presents Euclidean, MAX and Sector method to reduce the high complexity of LLR method. We propose optimal bit splitting method for three iterative codes.

• Nuclear Engineering and Technology
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• v.9 no.1
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• pp.7-13
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• 1977

This paper attempted to investigate the temperature characteristics and electrical conduction when low density polyethylene is irradiated. It was found that the log $\rho$ versus 1/T in irradiated polyethylene specimen resulted in different characteristics when it was heated upto above the melting point from when it was heated at the beginning stage. It was also found that the relation between the temperature and volume resistivity represented jumping phenomenon and that crystallization by thermal change was closely related to the fusion of crystalline region.

• Microbiology and Biotechnology Letters
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• v.47 no.3
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• pp.332-336
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• 2019

The use of ultraviolet (UV) spectroscopy for foods is known to have a microbial inhibitory effect. UV-A having a longer wavelength than UV-C can be used for continuous or intermittent UV irradiation of food stored in containers or packages. Because UV-LED can be used effectively at a low price, this study reported the effect of UV-A 365 nm-LED on inhibiting Bacillus subtilis in accordance with the packaging conditions employed in daily use. The packaging materials were linear low-density polyethylene (LLD-PE), nylon/low density polyethylene (LDPE), polystyrene, and glass. When all packaging materials were treated with 365 nm UV-LED, B. subtilis was observed to remain inactive for 30-60 min. Further, compared with the control (-log 5), the survival rate of B. subtilis was -log 2.0-2.5 for nylon/LDPE and -log 2.58-3.61 for LLD-PE. These packaging materials showed an excellent inhibitory effect regardless of their thickness. Typically, a decrease in the viable cell count of more than 3 log indicates a 99.9% bactericidal effect. These results suggest that 365 nm UV-LED permeated the packaging material and inhibited bacterial growth.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.57.2-57.2
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• 2014

Protostellar jets and outflows are signatures of star formation and promising mechanisms for driving supersonic turbulence in molecular clouds. We quantify outflow-driven turbulence through three-dimensional numerical simulations using an isothermal version of the total variation diminishing code. We drive turbulence in real space using a simplified spherical outflow model, analyze the data through density probability distribution functions (PDFs), and investigate density and velocity power spectra. The real-space turbulence-driving method produces a negatively skewed density PDF possessing an enhanced tail on the low-density side. It deviates from the log-normal distributions typically obtained from Fourier-space turbulence driving at low densities, but can provide a good fit at high densities, particularly in terms of mass-weighted rather than volume-weighted density PDF. We find shallow density power-spectra of -1.2. It is attributed to spherical shocks of outflows themselves or shocks formed by the interaction of outflows. The total velocity power-spectrum is found to be -2.0, representative of the shock dominated Burger's turbulence model. Our density weighted velocity power spectrum is measured as -1.6, slightly less that the Kolmogorov scaling values found in previous works.

• 한국지구물리탐사학회:학술대회논문집
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• 2010.10a
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• pp.159-160
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• 2010

• Korean Journal of Radiology
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• v.24 no.9
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• pp.849-859
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• 2023

Objective: The prognostic value of the volume and density of skeletal muscles in the abdominal waist of patients with colon cancer remains unclear. This study aimed to investigate the association between the automated computed tomography (CT)-based volume and density of the muscle in the abdominal waist and survival outcomes in patients with colon cancer. Materials and Methods: We retrospectively evaluated 474 patients with colon cancer who underwent surgery with curative intent between January 2010 and October 2017. Volumetric skeletal muscle index and muscular density were measured at the abdominal waist using artificial intelligence (AI)-based volumetric segmentation of body composition on preoperative pre-contrast CT images. Patients were grouped based on their skeletal muscle index (sarcopenia vs. not) and muscular density (myosteatosis vs. not) values and combinations (normal, sarcopenia alone, myosteatosis alone, and combined sarcopenia and myosteatosis). Postsurgical disease-free survival (DFS) and overall survival (OS) were analyzed using univariable and multivariable analyses, including multivariable Cox proportional hazard regression. Results: Univariable analysis showed that DFS and OS were significantly worse for the sarcopenia group than for the non-sarcopenia group (P = 0.044 and P = 0.003, respectively, by log-rank test) and for the myosteatosis group than for the non-myosteatosis group (P < 0.001 by log-rank test for all). In the multivariable analysis, the myosteatotic muscle type was associated with worse DFS (adjusted hazard ratio [aHR], 1.89 [95% confidence interval, 1.25-2.86]; P = 0.003) and OS (aHR, 1.90 [95% confidence interval, 1.84-3.04]; P = 0.008) than the normal muscle type. The combined muscle type showed worse OS than the normal muscle type (aHR, 1.95 [95% confidence interval, 1.08-3.54]; P = 0.027). Conclusion: Preoperative volumetric sarcopenia and myosteatosis, automatically assessed from pre-contrast CT scans using AI-based software, adversely affect survival outcomes in patients with colon cancer.

• Korean Journal of Environmental Agriculture
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• v.38 no.4
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• pp.254-261
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• 2019

BACKGROUND: Agricultural water is known to be one of the major routes in bacterial contamination of fresh vegetable. However, there is a lack of fundamental data on the microbial safety of agricultural water in Korea. METHODS AND RESULTS: We investigated the density of indicator bacteria in the surface water samples from 31 sites collected in April, July, and October 2018, while the groundwater samples were collected from 20 sites within Jeollabuk-do in April and July 2018. In surface water, the mean density of coliform, fecal coliform, and Escherichia coli was 2.7±0.55, 1.9±0.71, and 1.4±0.58 log CFU/100 mL, respectively, showing the highest bacterial density in July. For groundwater, the mean density of coliform, fecal coliform, and E. coli was 1.9±0.58, 1.4±0.37, and 1.0±0.33 log CFU/ 100mL, respectively, showing no significant difference between sampling time. The survival of E. coli O157:H7 were prolonged in water with higher organic matter contents such as total nitrogen (TN), and nitrate-nitrogen (NO₃-N). The reduction rates of E. coli O157:H7 in the water showed greater in order of 25, 35, 5, and 15℃. CONCLUSION: These results can be utilized as fundamental data for prediction the microbiological contamination of agricultural water and the development of microbial prevention technology.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.5
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• pp.607-617
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• 1998

Comparisons of joint probability density distribution obtained from the raw data of measured droplet sizes and velocities in a transient diesel fuel spray with computed joint probability density function were made. Simultaneous droplet sizes and velocities were obtained using PDPA. Mathematical probability density functions which can fit the experimental distributions were extracted using the principle of maximum likelihood. Through the statistical process of functions, mean droplet diameters, non-dimensional mass, momentum and kinetic energy were estimated and compared with the experimental ones. A joint log-hyperbolic density function presents quite well the experimental joint density distribution which were extracted from experimental data.

• Communications for Statistical Applications and Methods
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• v.2 no.1
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• pp.112-121
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• 1995

Let $p_1$ and $p_2$ be the proportions of two populations. To test the hypothesis $H_0 : p_1 = p_2$, we usually use the $x^2$ statistic, the large sample binomial statistic Z, and the Generalized Likelihood Ratio statistic-2log $\lambda$developed based on different mathematical rationale, respectively. Since testing the above hypothesis is equivalent to testing whether two populations follow the common Bernoulli distribution, one may also test the hypothesis by comparing 1 with the ratio of each density estimate and the hypothesized common density estimate, called comparison density, which was devised by Parzen(1988). We show that the above traditional test statistics ate actually estimating the measure of distance between the true densities and the common density under $H_0$ by representing them with the comparison density.

• Journal of the Korean Data and Information Science Society
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• v.25 no.1
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• pp.227-235
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• 2014

In this paper, we develop the noninformative priors for the scale parameter and the shape parameter in the log-logistic distribution. We developed the first and second order matching priors. It turns out that the second order matching prior matches the alternative coverage probabilities, and is a highest posterior density matching prior. Also we revealed that the derived reference prior is the second order matching prior for both parameters, but Jerffrey's prior is not a second order matching prior. We showed that the proposed reference prior matches the target coverage probabilities in a frequentist sense through simulation study, and an example based on real data is given.