• Food Science and Preservation
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• v.18 no.3
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• pp.423-428
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• 2011

Inactivation kinetic data of Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus, Salmonella Typhimurium, and Salmonella Enteritidis via treatment with aqueous chlorine dioxide treatment at a specific concentration were evaluated using the first-order kinetic and Weibull models. The Weibull model showed a better fit with the kinetic data than the first-order kinetic model. The survival curves after the aqueous chlorine dioxide treatment showed $t_R$ values(time required to reduce microbial populations by 90%) of 2.49 min for E. coli O157:H7 at 5 ppm, 1.47 min for L. monocytogenes at 5 ppm, 0.94 min for S. aureus at 5 ppm, 0.87 min for S. Typhimurium at 1 ppm, and 0.08 min for S. Enteritidis at 1 ppm, according to the Weibull model.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.2
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• pp.10-18
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• 2010

Scramjet engine is one of the core parts of hypersonic vehicle of next generation and being investigated by many countries. Korea Aerospace Research Institute performed a ground test of the model scramjet engine S1 in 2007. And, S2 model which is improved from S1 model in engine startability and thrust was tested with HIEST (High Enthalpy Shock Tunnel) at Kakuda Space Center of JAXA. Design condition of S2 model was Mach 6.7, however, it was tested at Mach 7.7 as an off-design condition test. As a test result, flow separation was found at the inside of the intake, but the engine showed stable combustion pressure distribution. Furthermore, compared to other test models, S2 model showed a good performance value in thrust and specific impulse.

• Food Science of Animal Resources
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• v.32 no.1
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• pp.62-67
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• 2012

This study calculated kinetic parameters of Escherichia coli O157:H7 and developed a probabilistic model to estimate growth probabilities of E. coli O157:H7 on polyethylene cutting boards as a function of temperature and time. The surfaces of polyethylene coupons ($3{\times}5$ cm) were inoculated with E. coli O157:H7 NCCP11142 at 4 Log $CFU/cm^2$. The coupons were stored at 13 to $35^{\circ}C$ for 12 h, and cell counts of E. coli O157:H7 were enumerated on McConkey II with sorbitol agar every 2 h. Kinetic parameters (maximum specific growth rate, Log $CFU/cm^2/h$; lag phase duration, h; lower asymptote, Log $CFU/cm^2$; upper asymptote, Log $CFU/cm^2$) were calculated with the modified Gompertz model. Of 56 combinations (temperature${\times}$time), the combinations that had ${\geq}$0.5 Log $CFU/cm^2$ of bacterial growth were designated with the value of 1, and the combinations that had increases of <0.5 Log $CFU/cm^2$ were given the value 0. These growth response data were fitted to the logistic regression to develop the model predicting probabilities of E. coli O157:H7 growth. Specific growth rate and growth data showed that E. coli O157:H7 cells were grown at $28-35^{\circ}C$, but there were no obvious growth of the pathogen below $25^{\circ}C$. Moreover, the developed probabilistic model showed acceptable performance to calculate growth probability of E. coli O157:H7. Therefore, the results should be useful in determining upper limits of working temperature and time, inhibiting E. coli O157:H7 growth on polyethylene cutting board.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.207-209
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• 2003

Quantifying crop production is one of the most important applications of remote sensing in which the temporal and up-to-date data can play very important role in avoiding any immediate insufficiency in agricultural production. A combination of climatic data and biophysical parameters derived from Landsat7 ETM+ was used to develop a mathematical model for wheat yield forecast in different geographically wide Wheat growing districts in Egypt. Leaf Area Index (LAI) and fraction of Absorbed Photosynthetically Active Radiation (fAPAR) with temperature were used in the modeling. The model includes three sub-models representing the correlation between the reported yield and each individual variable. Simulation results using district statistics showed high accuracy of the derived correlations to estimate wheat production with a percentage standard error (%S.E.) of 1.5% in El- Qualyobia district and average (%S.E.) of 7% for the whole wheat areas.

• The Journal of the Acoustical Society of Korea
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• v.27 no.2
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• pp.92-101
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• 2008

To dissolve the multi-layered model problems, and to complement 2-layered model's simplicity, assumed fluid-fluid-solid 3-layered model. Generally it is known that if the sediment thickness is more than 10 wavelength, the half space's influence to the in-water acoustic field could be disregarded. By tracking the maximum correlation coefficient of calculated results and experimental ones we confirmed that the requirement could be more realized. To calculate the maximum correlation coefficient we used single sensor transmission loss. On the assumption that the sediment sound velocity was 1813 m/s and frequency range 50 kHz to 120 kHz, the conversion condition was from 2.5 to 7.7 wavelength.

• Computers and Concrete
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• v.7 no.2
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• pp.87-102
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• 2010

This paper discusses new capabilities developed for the Virtual Penetration Laboratory (VPL) software package to address the challenges of determining Penetration Resistance (PR) equations for concrete materials. Specifically, the paper introduces a three-invariant concrete constitutive model recently developed by the authors. The Advanced Fundamental Concrete (AFC) model was developed to provide a fast-running predictive model to simulate the behavior of concrete and other high-strength geologic materials. The Continuous Evolutionary Algorithms (CEA) automatic fitting algorithms used to fit the new model are discussed, and then examples are presented to demonstrate the effectiveness of the new AFC model. Finally, the AFC model in conjunction with the VPL software package is used to develop a PR equation for a concrete material.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.10
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• pp.1007-1013
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• 2020

This study aims to understand the determinant of the employee's intention to use information system within the framework of the Technology Acceptance Model (TAM) and Information System Success Model (ISSM). This paper also aims to examine the influence of ISSM dimension on the perceived usefulness and the perceived ease of use. The research respondents were 248 employees of Universitas Negeri Semarang (UNNES) who are users of the Financial Information System (SIKEU). Data was obtained using a questionnaire that was distributed online via Google form. The data analysis method used is Structural Equation Model (SEM) analysis using the Warp-PLS software. The results showed that the dimensions of TAM (perceived ease of use and perceived usefulness) had a positive and significant influence on the employee's intention to use SIKEU. The ISSM dimension (system quality and information quality) also had a significant influence, although other ISSM dimensions (service quality) had not been proven to have a significant influence on the employee's intention to use SIKEU. Moreover, the results showed that the employee's intention to use is a determinant of SIKEU's actual usage. Perceived ease of use was significantly determined by system quality, information quality, and service quality. In addition, the perceived usefulness was significantly determined by system quality and information quality.

• Korean Journal of Optics and Photonics
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• v.17 no.4
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• pp.305-311
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• 2006

We propose a 7-level atom model, which takes into account two-photon coherence effects in saturation absorption spectroscopy. Using this model we explained spectral change with laser intensity and some of crossover resonance lines, which cannot be explained with Nakayama theory. The 7-level model consists of two upper levels and five lower levels, which account for $\pi-\pi$ polarization of both pump and probe beams in Zeeman sub levels. We compared our 7-level model with 4-level Nakayama theory for 5S$_{1/2}$ - 5P$_{1/2}$ transition line in $^{85}$Rb atoms. The results of the 7-level model calculation agree well the saturation absorption spectra data according to laser intensities.

• Clinical and Experimental Pediatrics
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• v.62 no.8
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• pp.317-323
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• 2019

Purpose: Investigating the prevalence of hyperuricemia and its association with metabolic syndrome (MetS) and cardiometabolic risk factors (CMRFs) in Korean children and adolescents. Methods: This cross-sectional survey used data from the 7th Korea National Health and Nutrition Examination Survey (2016-2017); 1,256 males and females aged 10-18 years were included. Hyperuricemia was defined as serum uric acid levels were >6.6 mg/dL at 10-11 years of age (both sexes), >7.7 mg/dL for males at 12-18 years of age and >5.7 mg/dL for females at 12-18 years of age. MetS was defined by the International Diabetes Federation criteria. Logistic regression analysis was used to analyze hyperuricemia-associated risk factors. Results: The prevalence of hyperuricemia was 9.4% (male, 8.4%; female, 10.5%) (P<0.281). After adjusting for sociodemographic factors and health behaviors in multivariate analysis (model 1), the odds ratio (OR) for hyperuricemia of MetS was 3.05 (95% confidence interval [CI], 1.17-7.92; P=0.022). After adjusting for the same variables in model 1 plus obesity and all MetS components (model 2), only abdominal obesity was significant, and the OR for hyperuricemia was 3.38 (95% CI, 1.72-6.63; P<0.001) After adjusting for the same variables in model 1 plus body mass index (BMI) z scores and all MetS components except abdominal obesity (model 3), only BMI z scores was significant, and the OR for hyperuricemia was 1.59 (95% CI, 1.34-1.89; P<0.001). Conclusion: MetS, abdominal obesity, and BMI z scores were CMRFs significantly associated with hyperuricemia in Korean children and adolescents. Therefore, attention should be paid to hyperuricemia in patients with obesity or MetS.

• International Journal of Advanced Culture Technology
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• v.12 no.1
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• pp.202-208
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• 2024

Objective: The purpose of this study is to examine the competitive environment of 7-Eleven using Porter's 5 Force model to analyze the specific competitiveness of 7-Eleven that has maintained continuous growth as a competitive company. Methods: This study is a case study of 7-Eleven. Results: As a result of the analysis, 7-Eleven has reinforced its competitiveness with existing competitors by raising entry barriers by expanding domestic stores and developing overseas convenience store business, focusing on North America, based on economy of scale. In addition, 7-Eleven seeks to differentiate itself from other convenience stores by developing a "private brand" and strengthens its bargaining power with suppliers through the development of new products by gathering information and know-how of experts in product development based on customer needs. The bargaining power with customers has been strengthened by building loyalty and trust in the brand by allowing consumers to purchase the same products at the same price no matter which store they visit. As a threat to potential competitors, 7-Eleven has secured a competition advantage by raising the barrier to entry by concentrating stores in specific areas through a dominant franchise development strategy and increasing awareness of 7-Eleven among consumers. In the case of threats from substitute products, it was confirmed that 7-Eleven has overcome the threat from substitute products by opening 24 hours a day and providing various services such as ATMs and copiers.