• Journal of the Korean Society for Precision Engineering
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• v.30 no.8
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• pp.802-808
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• 2013

Thermal barrier coating (TBC) is used to protect substrates and extend the operating life of gas turbines in power plant and aeronautical applications. The major causes of failure of such coatings is spallation, which results from thermal stress due to a thermal expansion coefficient mismatch between the top coating and the bond coating layers. In this paper, the effects of the material properties and the thickness of the top coating layer on thermal stresses were evaluated using the finite element method and the equation for the thermal expansion coefficient mismatch stress. In addition, we investigated a design technique for the top coating whereby thermal resistance is exploited.

• Journal of the Korean Dietetic Association
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• v.30 no.2
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• pp.95-111
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• 2024

The Smart Hazard Analysis Critical Control Point (HACCP) management system, which integrates information technology (IT) to automate and analyze big data, has been introduced into school food services. This study investigated the job performance, job satisfaction, and job stress of employees in school food services using Smart HACCP. Data were collected via questionnaires from 350 employees in school food services who utilized Smart HACCP and worked in Gyeonggi-do or Incheon. The questionnaire included general information, workplace characteristics, HACCP education status, job performance, and job satisfaction according to the use of Smart HACCP, and general job stress. The responses showed that 92.3% of the participants had received HACCP education in the workplace, and 66.6% understood the content of the education. Among the HACCP process stages, CCP2 (Food Handling and Cooking) and CCP3 (Cooking Completion and Distribution) were the stages at which all participants were using Smart HACCP. CCP3 had the highest percentage (61.4%) of participants who experienced feeling the maximum reduction in their tasks by using Smart HACCP. The Smart HACCP job performance at CCP1 (Inspection) and Smart HACCP job satisfaction were higher in workplaces with 6~10 employees, compared to those with 10≤ employees (both P<0.05). The Smart HACCP job performances at of CP1 (Refrigeration and Freezer Temperature Management) and CP2 (Cleaning and Disinfection of Food Contact Surfaces) were significantly affected by the work area. General job stress was significantly higher in cooks than in cook practitioners, higher in employees with cook certification than in those without it, and higher in employees with work experience (<1 year), compared to those with 5~10 years or 10~15 years' experience. In conclusion, employees' job performance and satisfaction with Smart HACCP need to be enhanced to improve hygiene in school food service. This requires the effective management of their job stress.

• Journal of Microbiology and Biotechnology
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• v.19 no.12
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• pp.1527-1535
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• 2009

Polyphosphate (polyP) plays diverse physiological functions in prokaryotes and eukaryotes, but most of their detailed mechanisms are still obscure. Here, we show that deletion of polyphosphate kinase (PPK), the principal enzyme responsible for synthesis of polyP, resulted in augmented expression of cAMP receptor protein (CRP) and rpoS and lowered $H_2O_2$ sensitivity in Salmonella Typhimurium ATCC14028. The binding of cAMP-CRP complex to rpoS promoter and further stimulation of its transcription were proved through electrophoretic mobility shift assay, lacZ fusion, and exogenous cAMP addition, respectively. The rpoS expression increased in cpdA (cAMP phosphodiesterase coding gene) mutant, further suggesting that cAMP-CRP upregulated rpoS expression. These results demonstrate that PPK affects oxidative stress response by modulating crp and rpoS expression in S. Typhimurium.

• Journal of agricultural medicine and community health
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• v.18 no.2
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• pp.173-183
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• 1993

This study reports the relationship between life-style and physical, mental health status in college students. The questionnaire survey was carried out from September to October, 1991. The questionnaire included life-style, physical health condition centered on unhealthy habits and complaints about physical symptoms, and mental condition which was assessed by Zung's self-rating depression scale(SDS). Days absent from school during the last year in males(3.6) were significantly more than those in females (1.0). Days catching the common cold were more in females than in males. The amount of complaints and the SDS score were significantly higher in females than in males. In the relationship between physical and mental health status and individual health habits, abscence-days from school significantly correlated with regular life, snacking, physical exercise, smoking, drinking. The amount of complaints and the SDS score were significantly associated with regular life, regular meal-time, eating breakfast, nutritional balance and physical exercise. In the relationship between health practice index to health status, the group having good habits showed significantly less days catching the common cold, less complaints, less SDS score and less amount of stress. It was also shown that life-style correlated with physical and mental health status.

• Proceedings of the Korean Biophysical Society Conference
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• 2002.06b
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• pp.55-55
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• 2002

An alternative sigma factor as encoded by the $\sigma$$\^$B/ gene in Streptomyces coelicolor A3(2) was known to be involved in the differentiation and osmotic stress response. Protein expression profiles of wild-type and a $\sigma$$\^$B/ mutant strain of S coelicolor A3(2), which is impaired in defense against osmotic stress, were compared in the absence and presence of osmotic stress, using 2-dimentional gel electrophoresis.(omitted)

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.6
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• pp.516-521
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• 2006

The use of gltA gene, as a new biomarker for environmental stress biomonitoring, was investigated because of its key position as the first enzyme of the tricarboxylic acid (TCA) cycle. A recombinant bioluminescent Escherichia coli strain, EBJM2, was constructed using a plasmid carrying the citrate synthase (gltA) promoter transcribing the Photorhabdus luminescens IuxCDABE genes (gltA::luxCDABE). The responses from this strain were studied with five different classes of toxicants: DNA damage chemicals, phenolics, oxidative-stress chemicals, PAHs, and organic solvents. EBJM2 responded strongly to DNA damage chemicals, such as mitomycin C (MMC) and methyl-nitro-nitrosoguanidine (MNNG) and nalidixic acid with the strongest responses. In contrast, tests with several compounds from the other four classes of toxicants gave no significant response. Therefore, EBJM2 was found to be sensitive to DNA damage chemicals.

• Journal of Families and Better Life
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• v.14 no.4
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• pp.263-276
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• 1996

The purpose of this study is to explore various environmental factors that explain parenting practices. Those factors considered are stress and characteristics of single-mother/child together with psychological distress experienced by the single mother. A total of 285 poor single mothers with a child attending elementary school or junior high school completed a structured questionaire. The relationships among the variables were analyzed by the path analysis. The results showed that poor single mothers rely on affectiv $e^portive involvement more frequently then punitive/inconsistent discipline. It is also confirmed that the enviromental factors such as financial stress living environmental stress and job status play important roles in determining the quality of parenting practices with the mediating role of psychological distress.ss.

• Animal Bioscience
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• v.34 no.2
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• pp.312-319
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• 2021

Objective: Stress-induced cytotoxicity caused by xenobiotics and endogenous metabolites induces the production of reactive oxygen species and often results in damage to cellular components such as DNA, proteins, and lipids. The cytochrome P450 (CYP) family of enzymes are most abundant in hepatocytes, where they play key roles in regulating cellular stress responses. We aimed to determine the effects of the antioxidant compound, methylsulfonylmethane (MSM), on oxidative stress response, and study the cytochrome P450 family 3 subfamily A (CYP3A) gene expression in fetal horse hepatocytes. Methods: The expression of hepatocyte markers and CYP3A family genes (CYP3A89, CYP3A93, CYP3A94, CYP3A95, CYP3A96, and CYP3A97) were assessed in different organ tissues of the horse and fetal horse liver-derived cells (FHLCs) using quantitative reverse transcription polymerase chain reaction. To elucidate the antioxidant effects of MSM on FHLCs, cell viability, levels of oxidative markers, and gene expression of CYP3A were investigated in H2O2-induced oxidative stress in the presence and absence of MSM. Results: FHLCs exhibited features of liver cells and simultaneously maintained the typical genetic characteristics of normal liver tissue; however, the expression profiles of some liver markers and CYP3A genes, except that of CYP3A93, were different. The expression of CYP3A93 specifically increased after the addition of H2O2 to the culture medium. MSM treatment reduced oxidative stress as well as the expression of CYP3A93 and heme oxygenase 1, an oxidative marker in FHLCs. Conclusion: MSM could reduce oxidative stress and hepatotoxicity in FHLCs by altering CYP3A93 expression and related signaling pathways.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.4
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• pp.1637-1642
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• 2015

Background: RhoGTPase-activating proteins (RhoGAPs) regulate RhoGTPases in cells, but whether individual reactive oxygen species (ROS) regulate RhoGAPs is unknown. Our previous published papers have shown that deleted in liver cancer 1 (DLC1) inhibits cancer cell migration by its RhoGAP activity. The present study was designed to explore the role of $H_2O_2$ in regulation of DLC1. Materials and Methods: We treated cells with $H_2O_2$ for 24h and phenotypic changes were analyzed by MTT, RT-PCR, Western blotting, immunofluorescence staining and wound healing assays. Results: $H_2O_2$ downregulated cyclin D1 and cyclin E to inhibit proliferation, and upregulated BAX to induce apoptosis in MCF-7 cells. Compared with non-tumorigenic cells, $H_2O_2$ increased expression of DLC1 and reduced activity of RhoA in cancer cells. Stress fiber production and migration were also suppressed by $H_2O_2$ in MDA-MB-231 cells. Conclusions: Our study suggests that $H_2O_2$ inhibits proliferation through modulation of cell cycle and apoptosis-related genes, and inhibits migration by decreasing stress fibers via DLC1/RhoA signaling.

• Journal of Ship and Ocean Technology
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• v.3 no.4
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• pp.35-51
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• 1999

Fatigue strength assessment procedures have been implemented in the ship design rules by many classification societies. However, a large variation tin the details of the different approaches exists in practically all aspects influding load history assessment, stress evaluation and fatigue strength assessment. In order to assess the influences of thesd variations on the prediction of fatigue lives. a comparative study is organized by the ISSC Committee III.2 Fatigue and Fracture. A pad detail on the top of longitudinal hatch coaming of a panamax container vessel is selected for fatigue calculation. The work described in this paper is one set of results of this comparative study in which the ABS dynamics approach is applied. Through this analysis the following conclusions can be drawn. (1) With the original ABS approach, the fatigue life of this pad detail is very low, only 2.398 years. (2) The treatment of the stillwater bending moment in the ABS approach might be a source of conservatism. If the influence of stillwater bending moment is ignored, then the fatigue life for this pad detail is 7.036 years. (3) The difference between the nominal stress approach and the hot spot stress approach for this pad detail is about 26%.