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.

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.

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.

IR-Band Conversion of Target and Background Using Surface Temperature Estimation and Error Compensation for Military IR Sensor Simulation.

Military infrared (IR) imaging systems utilize one or more IR wavelength-bands, among short wavelength IR (SWIR), middle wavelength IR (MWIR), and long wavelength IR (LWIR) band. The IR image wavelength-band conversion which transforms one arbitrary IR wavelength-band image to another IR wavelength-band image is needed for IR signature modeling and image synthesis in the IR systems. However, the IR wavelength-band conversion is very challenging because absorptivity and transmittance of objects and background (atmosphere) are different according to the IR wavelength band and because radiation and reflectance characteristics of the SWIR are very different from the LWIR and MWIR. Therefore, the IR wavelength-band conversion in this paper applies to only IR targets and monotonous backgrounds at a long distance for military purposes. This paper proposes an IR wavelength-band conversion method which transforms one arbitrary IR wavelength-band image to another IR wavelength-band image by using the surface temperature estimation of an object and the error attenuation method for the estimated temperature. The surface temperature of the object is estimated by an approximated Planck's radiation equation and the error of estimated temperature is corrected by using the slope information of exact radiance along with the approximated one. The corrected surface temperature is used for generating another IR wavelength-band image. The verification of the proposed method is demonstrated through the simulations using actual IR images obtained by thermal equipment.

Effect of Aging and Freezing Conditions on Meat Quality and Storage Stability of 1++ Grade Hanwoo Steer Beef: Implications for Shelf Life.

This study was conducted to establish the shelf life of 1++ grade Hanwoo beef by evaluating the changes in meat quality and storage stability under distribution conditions similar to those during export to Hong Kong and China. Four muscles of the loin, striploin, tenderloin, and top round muscles were obtained from 10 animals of 1++ grade Hanwoo steers. The distribution conditions were 0, 7, or 14 d of aging at 2°C and continuous storage at -18°C for 0, 3, 6, or 9 mon. The lightness (CIE L*) values decreased as the duration of freezer storage increased (p<0.05). The water-holding capacity of 4 muscles increased as the aging time increased when they were frozen for 3 mon (p<0.05). The cooking loss values of the four muscles were significantly increased as the duration of freezer storage increased (p<0.05). The Warner-Bratzler shear force values were significantly decreased in the loin, striploin, and top round muscles as the aging time increased (p<0.05). The changes in volatile basic nitrogen (16.67-18.49 mg%) and thiobarbituric reactive substance values (0.75-0.82 mg MA/kg meat) were significantly increased when the meat was frozen for 9 mon after 14 d of aging. On the basis of these observations, the shelf life of 1++ grade Hanwoo beef during distribution should be limited to less than 9 mon of freezer storage at -18°C after 14 d of aging at 2°C.

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.

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.