• International Journal of Reliability and Applications
• /
• v.8 no.1
• /
• pp.1-16
• /
• 2007

In this paper, we derive exact explicit expressions for the triple and quadruple moments of the lower record values from inverse the Weibull (IW) distribution. Next, we present and calculate the coefficients of the best linear unbiased estimates of the location and scale parameters of IW distribution (BLUEs) for different choices of the shape parameter and records size. We then use the higher order moments and the calculated BLUEs to compute the mean, variance, and the coefficients of skewness and kurtosis of certain linear functions of lower record values. By using the coefficients of the skewness and kurtosis, we develop approximate confidence intervals for the location and scale parameters of the IW distribution using Edgeworth approximate values and then compare them with the corresponding intervals constructed through Monte Carlo simulations. Finally, we apply the findings of the paper to some simulated data.

• Communications for Statistical Applications and Methods
• /
• v.26 no.2
• /
• pp.91-102
• /
• 2019

In this paper, we propose a new estimation method based on a weighted linear regression framework to obtain some estimators for unknown parameters in a two-parameter Rayleigh distribution under a progressive Type-II censoring scheme. We also provide unbiased estimators of the location parameter and scale parameter which have a nuisance parameter, and an estimator based on a pivotal quantity which does not depend on the other parameter. The proposed weighted least square estimator (WLSE) of the location parameter is not dependent on the scale parameter. In addition, the WLSE of the scale parameter is not dependent on the location parameter. The results are compared with the maximum likelihood method and pivot-based estimation method. The assessments and comparisons are done using Monte Carlo simulations and real data analysis. The simulation results show that the estimators ${\hat{\mu}}_u({\hat{\theta}}_p)$ and ${\hat{\theta}}_p({\hat{\mu}}_u)$ are superior to the other estimators in terms of the mean squared error (MSE) and bias.

• Journal of Microbiology and Biotechnology
• /
• v.34 no.6
• /
• pp.1214-1221
• /
• 2024

The accumulating evidence substantiates the indispensable role of gut microbiota in modulating the pathogenesis of type 2 diabetes. Uncovering the intricacies of the mechanism is imperative in aiding disease control efforts. Revealing key bacterial species, their metabolites and/or metabolic pathways from the vast array of gut microorganisms can significantly contribute to precise treatment of the disease. With a high prevalence of type 2 diabetes in Inner Mongolia, China, we recruited volunteers from among the Mongolian population to investigate the relationship between gut microbiota and the disease. Fecal samples were collected from the Volunteers of Mongolia with Type 2 Diabetes group and a Control group, and detected by metagenomic analysis and untargeted metabolomics analysis. The findings suggest that Firmicutes and Bacteroidetes phyla are the predominant gut microorganisms that exert significant influence on the pathogenesis of type 2 diabetes in the Mongolian population. In the disease group, despite an increase in the quantity of most gut microbial metabolic enzymes, there was a concomitant weakening of gut metabolic function, suggesting that the gut microbiota may be in a compensatory state during the disease stage. β-Tocotrienol may serve as a pivotal gut metabolite produced by gut microorganisms and a potential biomarker for type 2 diabetes. The metabolic biosynthesis pathways of ubiquinone and other terpenoid quinones could be the crucial mechanism through which the gut microbiota regulates type 2 diabetes. Additionally, certain Clostridium gut species may play a pivotal role in the progression of the disease.

• The Korean Journal of Applied Statistics
• /
• v.27 no.3
• /
• pp.461-473
• /
• 2014

We consider condence intervals for high quantiles of heavy-tailed distribution. The asymptotic condence intervals based on the limiting distribution of estimators are considered together with bootstrap condence intervals. We can also apply a non-parametric, parametric and semi-parametric approach to each of these two kinds of condence intervals. We considered 11 condence intervals and compared their performance in actual coverage probability and the length of condence intervals. Simulation study shows that two condence intervals (the semi-parametric asymptotic condence interval and the semi-parametric bootstrap condence interval using pivotal quantity) are relatively more stable under the criterion of actual coverage probability.

• Journal of the Korea Safety Management & Science
• /
• v.17 no.1
• /
• pp.13-19
• /
• 2015

Continued efforts to build up Safety Management System(SMS) and to improve its efficiency in airports, to which customers have direct access, are taken for granted due to continuous development of the aviation industry in both quantity and quality and rapid growth of air transportation market. This thesis proposed efficient operation methods of SMS for domestic airport organizations including Incheon International Airport(IIA), the largest airport in South Korea, aiming at strengthening aviation safety from the perspective of airport operators who play a pivotal role in service provider SMS. Those are consolidation of the existing safety management organizations and various improvements to promote voluntary incident reporting system. To draw a proposal for the improvements, conducted a research on domestic safety management status, carried out an analysis on operating conditions and did a research on ICAO regulations, domestic legal system as well as statistics data. Relevant studies and researches were also gathered and analyzed. A search for further improvements can also help increase operational efficiency and promoting a higher-level of safety awareness among operators can establish mature safety culture at airports.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.25 no.1
• /
• pp.71-77
• /
• 2011

Gastric ulcer has multifactorial etiology, and the development of ulcer is known to be caused by gastric acidity, pepsin secretion, gastric motility and gastric mucosal blood flow. The ulcer results from the tissue necrosis and apoptotic cell death triggered by mucosal ischemia, free radical formation and cessation of nutrient delivery. The gastric mucosa is usually exposed to a wide range of aggressive insults, and has developed efficient mechanisms to repair tissue injury. The apoptotic process of gastric mucosa is triggered by the induction of such proapoptotic gene expression, such as BAX. The Bcl-2 family of proteins plays a pivotal role in the regulation of apoptosis. The maintenance of gastric mucosa integrity depends upon the ratio between cell proliferation and cell death. Stress-inducing factors may affect Bcl-2/BAX ratio and thus the rate of apoptosis through modulation of the expression of both proteins depends upon the experimental model. In addition to the regulation of apoptosis, new vessels have to be generated in order to ensure an adequate supply of oxygen and nutrients to the healing gastric mucosa. This events are regulated by several factors. Among them, such polypeptide growth factors, such as vascular endothelial growth factor (VEGF) regulates essential cell functions involved in tissue healing including cell proliferation and differentiation. The purpose of this study was carried to investigate whether Rhei Rhizoma administration might protect apoptotic cell death and promote angiogenesis in gastric mucosa. Sprague-Dawley rats were randomly divided into 4 groups; normal, saline, cimetidine and Rhei Rhizoma-treated group. The saline, cimetidine and Rhei Rhizoma extracts were orally administrated to each group and gastric ulcer was induced by HCl-EtOH solution. After 1 hour, the stomachs were collected for histological observation and immunohistochemistry. In results, Rhei Rhizoma proves to promote to heal wound in gastric ulcer in conclusion and the significant changes of BAX, Bcl-2 and VEGF quantity in gastric mucosa were observed. These results suggest that Rhei Rhizoma extract may promote incision wound healing and has protective effects on gastric ulcer in rats.

• Mass Spectrometry Letters
• /
• v.12 no.4
• /
• pp.192-199
• /
• 2021

Alpine glaciers harbor a large quantity of bio-labile dissolved organic matter (DOM), which plays a pivotal role in global carbon cycling as glacial-fed streams are headwaters of numerous large rivers. To understand the complexity, origin, and fate of DOM in glaciers and downstream-linked streams and lakes, we elucidated the molecular composition of DOM in two different Tibetan Plateau glaciers, eight glacial-fed streams and five lakes, using an ultrahigh-resolution 15 Tesla Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The compositional changes of the DOM samples revealed that glacier DOM mostly exhibited sulfur-containing organic compounds (CHOS species). We also found that aliphatic formulae contributed more than 50% of the total abundance of assigned molecules in glacier samples, and those compounds were significantly related to CHOS species. The CHO proportions of glacial-fed streams and lakes samples increased with increasing distance from glacial terminals. The relative contribution of terrestrial-derived organics (i.e., lignins and tannins) declined while microbial-originated organics (aliphatics) increased with increasing elevation. This suggested the gradual input of allochthonous materials from non-glacial environment and the degradation of microbe-derived compounds along lower elevations. Alpine glaciers are retreating as a result of climate change and they nourished numerous streams, rivers, and downstream-linked lakes. Therefore, the interpretations of the detailed molecular changes in glacier ice, glacial-fed streams, and alpine lakes on the Tibetan Plateau could provide broad insights for understanding the biogeochemical cycling of glacial DOM and assessing how the nature of DOM impacts fluvial ecosystems.

• Journal of Animal Science and Technology
• /
• v.62 no.6
• /
• pp.884-892
• /
• 2020

Corticosterone is known as a biological stress index in many species including birds. Feather corticosterone concentration (FCC) has increasingly been used as a measure for chronic stress status in broiler chickens. As sample preparation is the first step of analytical process, different techniques of feather matrix disruption need to be validated for obtaining better result in analysing corticosterone extraction. The current study was a validation of pulverizing the feather by bead beater (BB) and surgical scissors (SS) processing prior to corticosterone extraction in feather of broiler chickens. The type of feather processing prior to the hormone extraction may alter the final output. Thereby, finding a standard method according to laboratory facilities is pivotal. This study carried out to determine the effects of feather pulverization methods on the extraction amount of corticosterone in broiler chickens. Feathers were sampled from four weeks old Ross 308 broiler chickens (n = 12 birds). All broiler chickens were kept under the same environmental condition and had access to feed and water. Feather samples were assigned to one of the following processing methods 1) using a BB for pulverizing and 2) using a SS for chopping into tiny pieces. Each sample was duplicated into two wells during enzyme immunoassay (EIA) analysis to improve the accuracy of the obtained data. The results showed lower standard errors and constant output of FCC by using the BB method compared with the SS method. Overall comparison of FCC showed a significantly higher (p < 0.001) amount of the FCC in the BB compared with the SS. Overall, using the BB method is recommended over the SS method for feather processing due to the ability to homogenize a large number of samples simultaneously, ease of use and greater extraction of feather corticosterone.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.34 no.2
• /
• pp.139-147
• /
• 2024

Objective: The introduction of government support programs for small businesses in 1993 aimed to enhance awareness and capabilities in industrial health management among small business proprietors, marking a continuous expansion over the past three decades. Despite this growth, there has been a conspicuous absence of comprehensive evaluations regarding the efficacy of these initiatives. In response, this study endeavors to conduct a thorough policy evaluation. Method: Through a meticulous approach, we conducted an analysis of in-depth interviews with eight individuals possessing expertise in the administration of government support programs for small businesses. These interviews were sourced from personnel affiliated with government ministries and public agencies. Results: In the analysis, it was found that small-scale business government support programs operate primarily based on quantity rather than receiving support from business owners regarding their necessity or utility. Consequently, these programs have failed to yield substantial effects on altering the perception of business owners or improving the working environment within the businesses. Conclusion: This study assumes significance in its capacity to discern intricate procedural challenges in program implementation, which often elude quantitative scrutiny. Furthermore, it provides pivotal insights for enhancing government support programs.

• Molecules and Cells
• /
• v.41 no.6
• /
• pp.582-590
• /
• 2018

Endothelial progenitor cells (EPCs) and outgrowth endothelial cells (OECs) play a pivotal role in vascular regeneration in ischemic tissues; however, their therapeutic application in clinical settings is limited due to the low quality and quantity of patient-derived circulating EPCs. To solve this problem, we evaluated whether three priming small molecules (tauroursodeoxycholic acid, fucoidan, and oleuropein) could enhance the angiogenic potential of EPCs. Such enhancement would promote the cellular bioactivities and help to develop functionally improved EPC therapeutics for ischemic diseases by accelerating the priming effect of the defined physiological molecules. We found that preconditioning of each of the three small molecules significantly induced the differentiation potential of $CD34^+$ stem cells into EPC lineage cells. Notably, long-term priming of OECs with the three chemical cocktail (OEC-3C) increased the proliferation potential of EPCs via ERK activation. The migration, invasion, and tube-forming capacities were also significantly enhanced in OEC-3Cs compared with unprimed OECs. Further, the cell survival ratio was dramatically increased in OEC-3Cs against $H_2O_2$-induced oxidative stress via the augmented expression of Bcl-2, a pro-survival protein. In conclusion, we identified three small molecules for enhancing the bioactivities of ex vivo-expanded OECs for vascular repair. Long-term 3C priming might be a promising methodology for EPC-based therapy against ischemic diseases.