Optimization of the Outlet Shape of an Air Circulation System for Reduction of Indoor Temperature Difference.

This study proposes an air circulation system that can forcibly circulate the lowest cold air to the top of indoor smart farms, and it has a width, length, and height of 6, 12, and 2.5 m, respectively, to reduce the effect of temperature differences between the upper and lower parts on the growth rate of plants in winter. This study also aimed to reduce the temperature deviation generated between the upper and lower parts of the target indoor space by optimizing the shape of the manufactured outlet of the air circulation system. A table of L9 orthogonal arrays, which is a design of experiment methodology, was used, and it presented three levels of the following design variables: blade angle, blade number, output height, and flow radius. Flow analysis was performed for the experiments on the nine models to minimize the high time and cost requirements. Based on the derived analysis results, an optimized prototype was manufactured by applying the Taguchi method, and experiments were conducted by installing 54 temperature points in an indoor space to identify the temperature difference between the upper and lower parts over time for the performance experiment. Under natural convection, the minimum temperature deviation was 2.2 °C and the temperature difference between the upper and lower parts did not decrease. For a model without an outlet shape, such as a vertical fan, the minimum temperature deviation was 0.8 °C and at least 530 s were required to reach a difference of less than 2 °C. When air was circulated in the air circulation system with the proposed outlet shape, the minimum temperature deviation was 0.6 °C and the time required to reach a difference of less than 2 °C was 440 s. Using the proposed air circulation system, cooling and heating costs are expected to be reduced in summer and winter because the arrival time and temperature difference between the upper and lower parts can be reduced using the outlet shape compared with the case without the outlet shape.

Design and Control of Multi-Plate MR Clutch Featuring Friction and Magnetic Field Control Modes.

A magnetorheological (MR) multi-plate clutch was proposed with both mechanical friction mode and magnetic field control modes. The magnetic field control mode was based on an MR fluid coupler that changed its viscous properties according to the density of an applied magnetic field. This mode was used in the early stage of clutch operation to reduce the impact of friction between the disc and plate, and eliminate to the extent possible the difference in their relative speeds when contacting each other in later stages. Once the rotational speed difference between the disc and plate was reduced, the clutch was operated in mechanical friction mode by compressing the friction surfaces together. A torque modeling equation was then derived for each mode based on the Bingham model of the MR fluid, and the transmission torque of the proposed multi-plate clutch was derived using these equations as well as magnetic field analysis results obtained using ANSYS Maxwell. A multi-plate MR clutch was then fabricated, and its torque transmission characteristics were evaluated in the magnetic field control and mechanical friction modes. The results confirmed that the model-based torque calculations were consistent with the observed transmission torque. Finally, control algorithms for mechanical friction only and mixed mechanical friction/magnetic field control torque tracking of the proposed MR multi-plate clutch were designed, and their performances were evaluated when applying unit step command, half-sine-wave command, and rotational speed changes. The results indicated that the torque tracking control was performed smoothly, demonstrating the advantages of the proposed clutch.

Methodology for Sound Quality Analysis of Motors for Automotive Interior Parts through Subjective Evaluation.

With the development of autonomous vehicles, activities in the indoor spaces of autonomous vehicles are diversifying. Therefore, as the operating range of the interior parts increases, the occupant becomes sensitive to the operating noise of autonomous vehicles. Therefore, to reduce operating noise, it is necessary to analyze the causal relationship between the mechanical/electrical noise characteristics of the motor and sound quality. In this paper, we propose a methodology to analyze the relationship between the noise frequency components and the sound quality of small motors used in automobile interior parts. Two types of motors were selected for this study, and noise measurements and analyses were performed by applying the design proposed in this study. Subjective sound quality evaluations were conducted using the 12 pairs of adjectives extracted from the survey. The results suggest that subjective sound quality evaluation scores should be converted to Z-scores to ensure the reliability of the statistical analysis. In addition, we present a critical sound quality value that can be used as a criterion for determining whether the sound quality is positive (good quality) or negative (bad quality). Sound quality regression models explain the causal relationship between rotational frequency components of the motor and subjective sound quality characteristics. Thus, a method for analyzing the effect of the rotational frequency component of the motor on the sound quality is presented, which suggests that it can be used as basic research data to improve the noise performance of the motor.

Can preoperative CA19-9 and CEA levels predict the resectability of patients with pancreatic adenocarcinoma?

BACKGROUND: We aimed to explore the predictive ability of preoperative carbohydrate antigen 19-9 (CA19-9) and carcinoembryonic antigen (CEA) levels for assessing tumor resectability (R0 resection) in patients with pancreatic adenocarcinoma. METHODS: The present study included 72 patients who had been treated surgically for potentially resectable pancreatic adenocarcinoma and 42 patients who had been treated surgically for palliation (bypass surgery) at our institution. Pancreatic adenocarcinoma was histologically confirmed by pathological examination of the resected specimen or, if unresected, by intraoperative biopsy. RESULTS: For resectable disease, the mean and median values of CA19-9 were significantly lower than for R1/2 or unresectable disease. The best cut-off points for CEA, CA19-9, and tumor size to predict resectability were 2.47 ng/mL, 92.77 U/mL and 11.85 cm(3), respectively. A CA19-9 > or = 92.77 U/mL and both tumor markers no less than the cut-off levels predicted the possibility of R1/2 or unresectability with 90.6% and 88.6% accuracy, respectively. However, either tumor marker or both tumor markers less than the cut-off levels predicted the probability of R0 resection only with 27.1% and 40.6% accuracy, respectively. The independent contributing factors to resectability (R0 resection) by multivariate regression analysis were a CA 19-9 < 92.77 U/mL, a tumor size < 11.85 cm(3), and a less advanced AJCC stage. CONCLUSION: The present study demonstrates that preoperative serum CA19-9 and CEA levels can be used for the prediction of resectability (R0 resection) in patients with pancreatic adenocarcinoma, which may enable a simple and cost-effective exclusion of such patients who are unlikely to benefit from surgery.

Comparison of insulin resistance and serum high-sensitivity C-reactive protein levels according to the fasting blood glucose subgroups divided by the newly recommended criteria for fasting hyperglycemia in 10059 healthy Koreans.

The increment for the prevalence of diabetes mellitus and impaired glucose tolerance warrants lowering the cutoffs of normoglycemia to help predict the future development of diabetes. The aim of this study was to find out whether insulin resistance and high-sensitivity C-reactive protein (hsCRP), a nontraditional cardiovascular risk factor, were related to the fasting glucose level, even in normoglycemic range that was categorized by the newly recommended criteria by the American Diabetes Association. Among the participants undergoing medical checkup program at Kangbuk Samsung Hospital, 10059 subjects (5535 men and 4524 women; mean age, 45 years) with normal fasting glucose levels, as defined by the newly recommended criteria (<5.6 mmol/L), were enrolled in this study. The blood pressures, body mass index (BMI), fasting blood glucose, fasting insulin, lipid batteries, and hsCRP levels were checked. The homeostatic model assessment-insulin resistance (HOMA-IR) and the quantitative insulin sensitivity check indexes (QUICKI) were calculated. All subjects were subdivided into 4 groups according to the fasting glucose level. The HOMA-IR, QUICKI, and log-transformed (log) hsCRP, or log(hsCRP), level significantly increased according to the increment in fasting glucose, and these associations were consistent after adjustment for age and BMI, except for the log(hsCRP) (P = .124 after adjustment). Log(hsCRP) increased as the HOMA-IR increased and as the QUICKI decreased, and when multiple regression analysis was done with log(hsCRP) as the dependent variable, age, high BMI, male sex, high HOMA-IR, hypertriglyceridemia, and low high-density lipoprotein cholesterol were the significant predictor for log(hsCRP). In conclusion, the insulin resistance indexes and hsCRP increased gradually even in the normal fasting glucose range, as categorized by the newly recommended criteria for abnormal fasting glucose levels, supporting the rationale for expanding the range of fasting hyperglycemia.

Application of the Prague C and M criteria for endoscopic description of columnar-lined esophagus in South Korea.

AIM: To ascertain whether the Prague circumferential (C) length and maximal (M) length criteria for grading the extent of Barrett's esophagus can be applied prior to its widespread application in South Korea. METHODS: Two hundred and thirteen consecutive cases with endoscopic columnar-lined esophagus (CLE) were included and classified according to the Prague C and M criteria. RESULTS: Of 213 cases with CLE, the distribution of maximum CLE lengths was: 0.5-0.9 cm in 99 cases (46.5%); 1.0-1.4 cm in 63 cases (29.6%); 1.5-1.9 cm in 15 cases (7.0%); 2.0-2.4 cm in 14 cases (6.6%); 2.5-2.9 cm in 1 case (0.5%); and 7.0 cm in 1 case (0.5%). Twenty cases (9.4%) had columnar islands alone. Two hundred and eight cases (97.7%) lacked the circumferential CLE component (C0Mx). Columnar islands were found in 70 cases (32.9%), of which 20 cases (9.4%) had columnar islands alone. CONCLUSION: In regions where most CLE patients display short or ultrashort tongue-like appearance, more detailed descriptions of CLE's in < 1.0 cm lengths and columnar islands, as well as avoidance of repeating the prefix "C0" need to be considered in parallel with the widespread application of the Prague system in South Korea.

Serum adipocyte-specific fatty acid-binding protein is associated with nonalcoholic fatty liver disease in apparently healthy subjects.

Adipocyte-specific fatty acid-binding protein (A-FABP) is a cytoplasmic protein that is expressed in adipocytes and is closely associated with insulin resistance, metabolic syndrome, and Type 2 diabetes. We investigated the relationship between A-FABP as a surrogate marker of metabolic syndrome and non-alcoholic fatty liver disease (NAFLD) in apparently healthy subjects. We assessed clinical and biochemical metabolic parameters and measured serum levels of A-FABP, high-sensitivity C-reactive protein and tumor necrosis factor-α (TNF-α) in 494 subjects who were divided into two groups according to the presence of NAFLD by abdominal ultrasonography. All parameters associated with metabolic syndrome were significantly higher in patients with NAFLD (P<.001). A-FABP showed positive correlation with TNF-α, homeostasis model assessment index of insulin resistance (HOMA-IR), and metabolic syndrome (P<.001) when adjusted for age and sex. The odds ratio for the risk of NAFLD in the highest tertile of A-FABP compared with the lowest tertile was 7.36 (CI 3.80-14.27, P<.001) after adjustment for age and sex; 4.52 (CI 2.22-9.20, P<.001) after adjustment for age, sex, HOMA-IR and metabolic syndrome and 2.86 (CI 1.11-7.35, P<.05) after further adjustment for all metabolic parameters including TNF-α. The serum level of A-FABP was independently associated with NAFLD and showed significant correlation with TNF-α, HOMA-IR, and metabolic syndrome.

Characteristics of advanced gastric cancer undetected on gastroscopy.

BACKGROUND/AIMS: Stomach cancer can be easily diagnosed via endoscopy, but also possible to be missed. The aim of this study was to investigate the clinical and endoscopic characteristics of advanced gastric cancers that were not diagnosed based on endoscopic examination. METHODS: We evaluated patients who had newly diagnosed advanced gastric cancer that was undetected via endoscopy within the last six months. RESULTS: Sixteen patients were included in this study. The locations of the cancers were the cardia in six cases, the greater curvature side of the body in eight cases and the antrum in two cases. The histological findings were tubular type adenocarcinoma in 11 cases, with ten cases of moderately to poorly differentiated adenocarcinoma and five cases of signet ring cell type adenocarcinoma. CONCLUSIONS: Even advanced gastric cancer lesions may not be detected during endoscopy. If a patient continues to complain of upper gastrointestinal symptoms, even though endoscopy does not find abnormal findings, repeated endoscopy and/or additional diagnostic studies should be considered.