• Nuclear Engineering and Technology
• /
• v.56 no.2
• /
• pp.688-706
• /
• 2024

Austenitic stainless steels (ASS) are extensively employed in various sectors such as nuclear, power, petrochemical, oil and gas because of their excellent structural strength and resistance to corrosion. SS304 and SS316 are the predominant choices for piping, pressure vessels, heat exchangers, nuclear reactor core components and support structures, but they are susceptible to stress corrosion cracking (SCC) in chloride-rich environments. Over the course of several decades, extensive research efforts have been directed towards evaluating SCC using diverse methodologies and models, albeit some uncertainties persist regarding the precise progression of cracks. This review paper focuses on the application of Acoustic Emission Technique (AET) for assessing SCC damage mechanism by monitoring the dynamic acoustic emissions or inelastic stress waves generated during the initiation and propagation of cracks. AET serves as a valuable non-destructive technique (NDT) for in-service evaluation of the structural integrity within operational conditions and early detection of critical flaws. By leveraging the time domain and time-frequency domain techniques, various Acoustic Emission (AE) parameters can be characterized and correlated with the multi-stage crack damage phenomena. Further theories of the SCC mechanisms are elucidated, with a focus on both the dissolution-based and cleavage-based damage models. Through the comprehensive insights provided here, this review stands to contribute to an enhanced understanding of SCC damage in stainless steels and the potential AET application in nuclear industry.

• Tuberculosis and Respiratory Diseases
• /
• v.61 no.4
• /
• pp.356-365
• /
• 2006

Background: Corticosteroids are known to be significant prognostic parameters in sepsis. Recently, an absolute and relative insufficiency of the corticosteroids system has often been reported to often develop particularly in severe sepsis. Degree of such an adrenal insufficiency not only has prognostic implications but also can be used to guide corticosteroids replacement therapy. The 24-hour urinary cortisol levels as well as serum cortisol concentrations were measured to assess the clinical significance and their relationship with the other parameters of sepsis, and also evaluated the clinical implications of the relative adrenal insufficiency. Methods: 26 consecutive patients with sepsis were enrolled. The basal random serum cortisol, ACTH, ADH, lactate levels and 24-hour urinary free cortisol amount were measured. The rapid ACTH ($250{\mu}g$) stimulation test was also performed. Results: Basal serum cortisol levels were higher in the non-survivors than in the survivors. The 24-hour urinary free cortisol levels were higher in the patients with severe sepsis than in those without. The serum cortisol levels strongly correlated with the serum ADH and lactate levels. The 24-hour urinary free cortisol levels strongly correlated with the serum cortisol and lactate levels. The fractional changes in the cortisol levels after the rapid ACTH stimulation tests correlated with the serum cortisol, ADH, and lactate levels. Conclusion: Both the serum cortisol and 24-hour urinary cortisol were found to be significant prognostic factors in sepsis, and showed a strong correlation with the other parameters. The relative adrenal insufficiency might also be an important clinical parameter.

• Journal of Nutrition and Health
• /
• v.44 no.4
• /
• pp.292-302
• /
• 2011

Adipocytokines (adiponectin, leptin and resistin) are known to play a major role in development of cardiovascular disease (CVD) and intervention program is effective in reducing CVD risk factors. However, intervention program to improve the CVD risk factors including adipocytokines has been less studied. This study investigated the effects of 12-weeks worksite intervention program on cardiovascular risk factors, adipocytokines and nutrients intakes in industrial workers. 157 industrial male workers (32 metabolic syndrome (MS) subjects, 125 healthy subjects using age-matched stratified random sampling) received 5 face-to-face counseling based on their health profiles. Anthropometry, biochemical parameters and nutrients intakes were measured. The diagnosis of MS was adapted from modified NCEP-ATP III criteria (2001) and Asia-Pacific definition criteria (2000) for waist circumference (WC). After the intervention program, WC, BMI, SBP, insulin, leptin and intakes of total energy and fiber were significantly decreased (p < 0.05), while adiponectin was significantly increased (p < 0.05) in MS subjects. The WC, BMI, SBP, total cholesterol, LDL and HDL-cholesterol, HbA1c, leptin and intakes of total energy, protein and fat were significantly decreased (p < 0.05) and adiponectin was significantly increased (p < 0.05) in normal subjects. Multiple linear regression revealed that adiponectin was positively correlated with HDL-cholesterol (p < 0.01). Leptin was positively correlated with WC (p < 0.01), and resistin was positively correlated with HbA1c (p < 0.05) and intakes of total energy (p < 0.05), and negatively correlated with HDL-cholesterol (p < 0.05). The results of the 12 weeks intervention showed a positive impact on adipocytokines and nutrients intakes of industrial workers to reduce cardiovascular risk factors. Further research is needed to verify a tailored long-term worksite intervention program including adipocytokines as a protective factor for the CVD.

• Journal of the Korean Geotechnical Society
• /
• v.15 no.4
• /
• pp.247-260
• /
• 1999

It was found that surface roughness has a first-order effect on the interface shear strength and accordingly it should be accurately quantified if its role is to be properly understood. Most of the surface roughness parameters are based on the trisector approach (three dimensional parameter) which can provide a good measure of the surface roughness from a static perspective. However, if roughness is to be correlated with a directional sensitive parameter such as interface shear then a two dimensional parameter could be more meaningful if the roughness measurements are made parallel to the direction of shearing. In this paper, alternative roughness parameters which consider the direction of shearing are described. These directional parameters are compared with the existing roughness parameters, and the relationship between these directional and non-directional parameters are investigated. The surface roughness was quantified by using the Optical Profile Microscopy (OPM) method (Dove and Frost, 1996) based on the digital image analysis. The results showed that the various surface roughness parameters measured in this study exhibit similar trend of roughness values, so that, good relationships are obtained between these roughness parameters. As the surface roughness increases, the roughness values measured in trisector coupons are increasing higher than those measured in parallel coupons.

• Journal of Korea Water Resources Association
• /
• v.57 no.7
• /
• pp.461-470
• /
• 2024

This study aimed to predict total phosphorus (T-P) to address early eutrophication caused by nutrient influx from various human activities. Traditional T-P monitoring systems are labor-intensive and time-consuming, leading to a global trend of using direct reading sensors. Therefore, this study utilized water quality parameters obtained from direct reading sensors in a two-stage T-P prediction process. The importance of turbidity (Tur) in T-P prediction was examined, and an analysis was conducted to determine if T-P prediction is possible using only direct reading sensor parameters by adding automatic water quality analyzer parameters. The study found that T-P concentrations were higher in the mid-lower reaches of the Nakdong River basin compared to the upper reaches. Pearson correlation analysis identified water quality parameters highly correlated with T-P at each site, which were then used in multiple linear regression analysis to predict T-P. The analysis was conducted with and without the inclusion of Tur, and the performance of models incorporating automatic water quality analyzer parameters was compared with those using only direct reading sensor parameters. The results confirmed the significance of Tur in T-P prediction, suggesting that it can be used as a foundational element in the development of measures to prevent eutrophication.

• Journal of the East Asian Society of Dietary Life
• /
• v.18 no.4
• /
• pp.489-498
• /
• 2008

This study was designed to evaluate the relationships among snack intake, obesity index, and blood parameters in obese elementary school children. Anthropometric measurements, nutrient intake from meals and snacks, serum cholesterol, glucose, GOT, GPT, and hemoglobin levels were obtained 36 obese elementary students (boys=28, girls=8). The average age, height, weight, % body fat, and obesity index were 11.9 years, 145.5cm, 53.5kg, 45.7%, and 32.4%, respectively. The mean energy intake was 1,818.7 kcal in boys and 1,818.1 kcal in girls. In addition, the energy intake from snacks was 470.4 kcal in boys and 479.4 kcal in girls. The levels of plant fat (p<0.05) and cholesterol (p<0.001) consumed during snacks (1,000 kcal per energy intake) were higher than those consumed during meals. The serum cholesterol, glucose, and hemoglobin levels were 177.4 mg/dL, 90.4 mg/dL, and 14.5 g/dL, respectively. In addition, the levels of serum GOT (p<0.001) and GPT (p<0.05) were higher in boys than in girls. Height was positively correlated with food intake (p<0.05), snack intake (p<0.05), and energy intake from snacks (p<0.05). Based on these results, further studies are needed in order to investigate the relationships among various aspects of snacking and obesity in elementary school children.

• Smart Structures and Systems
• /
• v.25 no.2
• /
• pp.135-153
• /
• 2020

There has been a sustained interest towards the non-contact structural displacement measurement by means of videogrammetric technique. On the way forward, one of the major concerns is the spurious image drift induced by temperature variation. This study therefore carries out an investigation into the temperature effect of videogrammetric technique, focusing on the exploration of the mechanism behind the temperature effect and the elimination of the temperature-caused measurement error. 2D videogrammetric measurement tests under monotonic or cyclic temperature variation are first performed. Features of measurement error and the casual relationship between temperature variation and measurement error are then studied. The variation of the temperature of digital camera is identified as the main cause of measurement error. An excellent linear relationship between them is revealed. After that, camera parameters are extracted from the mapping between world coordinates and pixels coordinates of the calibration targets. The coordinates of principle point and focal lengths show variations well correlated with temperature variation. The measurement error is thought to be an outcome mainly attributed to the variation of the coordinates of principle point. An approach for eliminating temperature-caused measurement error is finally proposed. Correlation models between camera parameters and temperature are formulated. Thereby, camera parameters under different temperature conditions can be predicted and the camera projective matrix can be updated accordingly. By reconstructing the world coordinates with the updated camera projective matrix, the temperature-caused measurement error is eliminated. A satisfactory performance has been achieved by the proposed approach in eliminating the temperature-caused measurement error.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.41 no.7
• /
• pp.524-531
• /
• 2013

This work aims at developing a RTB (Rotor Track and Balance) system to alleviate imbalances originating from various sources encountered during blade manufacturing process and environmental factors. The analytical RTB model is determined based on the linear regression analysis to relate the RTB adjustment parameters and their track and vibration results. The model is validated using the flight test data of a full helicopter. It is demonstrated that the linearized model has been correlated well with the test data. A hybrid optimization problem is formulated to find the best solution of the RTB adjustment parameters using the genetic algorithm combined with the PSO (Particle Swarm Optimization) algorithm. The optimization results reveal that both track deviations and vibration levels under various flight conditions become decreased within the allowable tolerances.

• Korean Journal of Clinical Laboratory Science
• /
• v.48 no.3
• /
• pp.196-201
• /
• 2016

An effective strategy for obesity intervention should include demographic, health-related, and work-related factors that are most relevant to the target population. Factors most strongly associated with obesity may differ for groups of individuals across industries or age categories. The purpose of this study was to provide current knowledge about the possible association between psychosocial job stress and immune parameters in blood. We assessed obesity-related parameters as well as the natural killer cell activity (NKCA) in female workers. There was a significant difference in the obesity-related blood parameters, i.e. fasting blood sugar level, according to age (p<0.05). Moreover, it showed a significant difference in NK cell activity between the obese and non-obese factor groups (p<0.05). Pearson correlation analysis demonstrated that NKCA was closely correlated with obesity related factors. In the future, it would have to study the biological changes which increase the activity of the immune factors to the immunological response.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.17 no.1
• /
• pp.31-42
• /
• 2007

Recently, concerns regarding indoor air quality in offices have continued to increase. Thirty offices in five metropolitan commercial buildings were surveyed from February to April 2004. Sampling was performed during normal business hours. Thermal comfort factors such as temperature and relative humidity, carbon dioxide ($CO_2$), carbon monoxide (CO), formaldehyde (HCHO), respirable dust, $PM_{10}$ were sampled and analyzed to determine the mean, standard deviation, range, and correlation for each of those parameters. The data was then compared to office as standard of Ministry of Labor, and guideline applicable to the indoor environment. The results represented that the temperature was slightly higher than the standard of American Society of Refrigerating and Air-Conditioning Engineers (ASHRAE), the relative humidity was lower that the standard of ASHRAE. The range of the 8-TWA concentration of $CO_2$ was 639 ~ 786 ppm, but 33.3% of the total thirty offices exceeded the 1000 ppm as ceiling concentration. The concentration of CO was less than 3 ppm, which was similar to that of offices in Japanese. The mean concentration of formaldehyde was 0.032 ppm, and only 2 % of total samples (193) exceeded the 0.1 ppm, standard of formaldehyde in office air. The concentration of respirable dust and $PM_{10}$ was not exceeded the standard of those parameters, $150{\mu}g/m^3$. The concentration of those parameters in the office air was statistically correlated.