• 한국연초학회지
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• 제6권2호
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• pp.155-168
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• 1984

Field test were conducted to select the best method for soil phosphorus test and to obtain the critical levels of each method for P fertilizer recommendations based on tobacco production. Truog method was recognized to be the mort suitable one for soil P test. N. Carolina, Bray No.1 and Olsen methods were followed in order. Bray No. 2 and Lancaster methods showed the least satisfaction. The critical levels of available P by lancaster, Bray No. 1, N. Carolina,01sen, and Truog methods were 55ppm, 32ppm, 21ppm, 19ppm, and 22ppm, respectively. Below the critical level a large yield response can be expected with 10kg $P_2O_5$/10a, above critical level little or no response is expected. In soils the more the initial available p, the more available P was carried over, while the more the total amount of silt and clay, the less the residual P was found. The increase in residual P by 10kg of $P_2O_5$ was greater than that of 5kg/10a. The chemical composition and the price of the cured leaf were not affected by the $P_2O_5$ application, indicating that the increase in the rate of $P_2O_5$ application would not exert on the quality of tobacco.

• Nonlinear Functional Analysis and Applications
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• 제29권1호
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• pp.35-45
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• 2024

In this paper, we study the existence and multiplicity of nontrivial solutions for a p-Kirchhoff equation involving critical Sobolev-Hardy exponent by using variational methods and we need to estimate the energy levels.

• Asian-Australasian Journal of Animal Sciences
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• 제31권4호
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• pp.537-547
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• 2018

Objective: This study was performed to understand transcriptional changes in the genes involved in gluconeogenesis and glycolysis pathways following castration of bulls. Methods: Twenty Korean bulls were weaned at average 3 months of age, and castrated at 6 months. Liver tissues were collected from bulls (n = 10) and steers (n = 10) of Korean cattle, and hepatic gene expression levels were measured using quantitative real-time polymerase chain reaction. We examined hepatic transcription levels of genes encoding enzymes for irreversible reactions in both gluconeogenesis and glycolysis as well as genes encoding enzymes for the utilization of several glucogenic substrates. Correlations between hepatic gene expression and carcass characteristics were performed to understand their associations. Results: Castration increased the mRNA (3.6 fold; p<0.01) and protein levels (1.4 fold; p<0.05) of pyruvate carboxylase and mitochondrial phosphoenolpyruvate carboxykinase genes (1.7 fold; p<0.05). Hepatic mRNA levels of genes encoding the glycolysis enzymes were not changed by castration. Castration increased mRNA levels of both lactate dehydrogenase A (1.5 fold; p<0.05) and lactate dehydrogenase B (2.2 fold; p<0.01) genes for lactate utilization. Castration increased mRNA levels of glycerol kinase (2.7 fold; p<0.05) and glycerol-3-phosphate dehydrogenase 1 (1.5 fold; p<0.05) genes for glycerol utilization. Castration also increased mRNA levels of propionyl-CoA carboxylase beta (mitochondrial) (3.5 fold; p<0.01) and acyl-CoA synthetase short chain family member 3 (1.3 fold; p = 0.06) genes for propionate incorporation. Conclusion: Castration increases transcription levels of critical genes coding for enzymes involved in irreversible gluconeogenesis reactions from pyruvate to glucose and enzymes responsible for incorporation of glucogenic substrates including lactate, glycerol, and propionate. Hepatic gluconeogenic gene expression levels were associated with intramuscular fat deposition.

• 공학교육연구
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• 제21권4호
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• pp.3-9
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• 2018

This paper explores the educational method of using films as a means to cultivate critical thinking abilities for engineering students. It provides a practical educational model that elaborates on how films could be used as case studies to draw relevant questions, and in the process of answering them, develop students' ability to think critically. The educational model proposes a learning method of enhancing critical thinking abilities through debates and essay writing on issues raised in films. Furthermore, the paper entails concrete learning objectives on critical thinking education, and standards to evaluate levels of enhancement. Through raising the critical thinking abilities of engineering students, this paper will contribute to the utilization of creative ideas in the process of engineering research. Furthermore, the concept of utilizing films as a model for education used in this study could be adapted for fields other than that of engineering.

• 한국학교수학회논문집
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• 제13권2호
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• pp.263-287
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• 2010

본 연구에서는 초등학생이 삼각형을 어떻게 정의하고 있으며, 삼각형인 예와 삼각형이 아닌 예의 식별 과정에서 나타난 학생들의 추론 유형을 조사하였다. 그리고 학생들의 추론 유형과 학생들의 기하적 수준이 어떤 관련성이 있는지 알아보았다. 연구 결과 대부분의 학생들은 세 개, 꼭짓점, 닫힌 도형, 직선성 등 도형의 본질적인 속성에 기초하여 삼각형을 식별하였으며, 몇 몇 학생들은 도형의 크기, 방향 등 도형의 비본질적인 속성에 기초하여 삼각형을 식별하였다. 특히 기하적 수준이 낮은 몇 몇 학생들은 도형의 전체적인 형태에 기초한 시각적 추론을 통하여 도형을 식별하였다.

• Clinical and Experimental Pediatrics
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• 제56권12호
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• pp.519-522
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• 2013

Timely diagnosis of hyponatremia is important for preventing potential morbidity and mortality as it is often an indicator of underlying disease. The most common cause of eurvolemic hyponatremia is the syndrome of inappropriate antidiuretic hormone (SIADH) secretion. Recent studies have demonstrated that proinflammatory cytokines such as interleukin (IL) $1{\beta}$ and IL-6 are involved in the development of hyponatremia, a condition that is associated with severe inflammation and is related to antidiuretic hormone (ADH) secretion. Serum sodium levels in hyponatremia are inversely correlated with the percentage of neutrophils, C-reactive protein, and N-terminal-pro brain type natriuretic peptide. Additionally, elevated levels of serum IL-6 and IL-$1{\beta}$ are found in inflammatory diseases, and their levels are higher in patients with hyponatremia. Because it is significantly correlated with the degree of inflammation in children, hyponatremia could be used as a diagnostic marker of pediatric inflammatory diseases. Based on available evidence, we hypothesize that hyponatremia may be associated with inflammatory diseases in general. Understanding the mechanisms responsible for augmented ADH secretion during inflammation, monitoring patient sodium levels, and selecting the appropriate intravenous fluid treatment are important components that may lower the morbidity and mortality of patients in a critical condition.

• Asia pacific journal of information systems
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• 제21권3호
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• pp.51-69
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• 2011

Security has been considered one of the most critical issues for managing IT resources in many organizations. Despite a growing interest and extensive research on security at various levels, little research has focused on the comparison of security knowledge levels between different cultures. The current study investigates and compares the security knowledge level between Korea and the U.S. Based on the literature review of spyware, Hofstede's cultural dimensions, and security knowledge, this study identifies three constructs (i.e., security familiarity, spyware awareness, and spyware knowledge) to examine the difference of security knowledge levels between Korea and the U.S. Six hundred ninety-six respondents from Korea and the U.S. participated in the survey, and an in-depth analysis based on analysis of covariance (ANCOVA) was carried out. The results show that the levels of security familiarity, spyware awareness, and spyware knowledge are significantly lower in Korea than in the U.S., as expected. These findings present a significant association between national culture and security knowledge, and the degree of individualism (or collectivism) plays an especially critical role in the perception of security. A number of implications for academia and practitioners emerge. Limitations and future research directions are discussed in the conclusion.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.2094-2099
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• 2004

An experimental study on heat transfer characteristics near the critical pressure has been performed with an internally-heated vertical annular channel cooled by R-134a fluid. Two series of tests have been completed: (a) steady-state critical heat flux (CHF) and (b) heat transfer tests for pressure reduction transients through the critical pressure. In the present experimental range, the steady-state CHF decreases with the increase of the system pressure For a fixed inlet mass flux and subcooling, the CHF falls sharply at about 3.8 MPa and shows a trend toward converging to zero as the pressure approaches the critical point of 4.059 MPa. The CHF phenomenon near the critical pressure does not lead to an abrupt temperature rise of the heated wall because the CHF occurred at remarkably low power levels. In the pressure reduction transient experiments, as soon as the pressure passed through the critical pressure, the wall temperatures rise rapidly up to a very high value due to the occurrence of the departure from nucleate boiling. The wall temperature reaches a maximum at the saturation point of the outlet temperature, then tends to decrease gradually.

• Nuclear Engineering and Technology
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• 제36권5호
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• pp.403-414
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• 2004

An experimental study of heat transfer characteristics near the critical pressure has been performed with an internally-heated vertical annular channel cooled by R-134a fluid. Two series of tests have been completed: (a) steady-state critical heat flux (CHF) tests, and (b) heat transfer tests for pressure reduction transients through the critical pressure. In the present experimental range, the steady-state CHF decreases with increase of the system pressure for fixed inlet mass flux and subcooling. The CHF falls sharply at about 3.8 MPa and shows a trend towards converging to zero as the pressure approaches the critical point of 4.059 MPa. The CHF phenomenon near the critical pressure does not lead to an abrupt temperature rise of the heated wall, because the CHF occurs at remarkably low power levels. In the pressure reduction transients, as soon as the pressure passes below the critical pressure from the supercritical pressure, the wall temperatures rise rapidly up to very high values due to the departure from nucleate boiling. The wall temperature reaches a maximum at the saturation point of the outlet temperature, and then tends to decrease gradually.

• Tuberculosis and Respiratory Diseases
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• 제85권3호
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• pp.237-248
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• 2022

Background: We evaluated the effect of particulate matter (PM) and cigarette smoke extract (CSE) on bronchial epithelial cell survival, as well as oxidative stress and autophagy levels. Moreover, we aimed to assess the effect of the antioxidant N-acetylcysteine (NAC) on the adverse effects of PM and CSE exposure. Methods: Normal human bronchial epithelial cells (BEAS-2B cells) were exposed to urban PM with or without CSE, after which cytotoxic effects, including oxidative stress and autophagy levels, were measured. After identifying the toxic effects of urban PM and CSE exposure, the effects of NAC treatment on cell damage were evaluated. Results: Urban PM significantly decreased cell viability in a concentration-dependent manner, which was further aggravated by simultaneous treatment with CSE. Notably, pretreatment with NAC at 10 mM for 1 hour reversed the cytotoxic effects of PM and CSE co-exposure. Treatment with 1, 5, and 10 mM NAC was shown to decrease reactive oxygen species levels induced by exposure to both PM and CSE. Additionally, the autophagy response assessed via LC3B expression was increased by PM and CSE exposure, and this also attenuated by NAC treatment. Conclusion: The toxic effects of PM and CSE co-exposure on human bronchial epithelial cells, including decreased cell viability and increased oxidative stress and autophagy levels, could be partly prevented by NAC treatment.