• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.20 no.7
• /
• pp.2277-2288
• /
• 1996

This study was performed to analyze the cooling effect of heated ribs which are frequently used for cooling of electronic parts, using the numerical method. To prevent the excessive pressure drop due to turbulence promoters for the enhancement of heat transfer rate especially, the effect of the angle of turbulence promoter was investigated by the numerical analysis. Heat transfer rate with turbulence promoters with rectangular cross-section increased by 13% in average, but the coefficient of pressure drop increased by 1.68 times than that without them. In the present study, triangular cross-sectional shape turbulence promoters were suggested and numerically tested. Pressure drop of turbulence promoter with the 30 degree triangular cross-sectional shape decreased by 30% from that of rectangular cross-section promoters while heat transfer rate was almost the same. While with 4 turbulence promoters, the heat transfer rate increased by 21%, the pressure drop increased 4 times. It means that the higher capacity of cooling fan should be needed. With the triangular cross-sectional shape, the size of vortex region at the rear of promoters became considerably smaller, so pressure drop became smaller. The effect of the change of cross-sectional shape was not found in the flow pattern near the ribs, so that heat transfer characteristics in the ribs were not changed.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.37 no.5
• /
• pp.39-48
• /
• 2000

We newly proposed a polymer based vertical asymmetric optical coupler, which was characterized by simple fabricating procedure and short coupling length. And we fabricated a thermo-optic modulator using the polymeric optical coupler. We optimized the proposed device by coupling characteristic analysis. In a TE polarized 1.33${\mu}{\textrm}{m}$ wavelength, we obtained very short coupling length(L=277.6${\mu}{\textrm}{m}$) with 0.4${\mu}{\textrm}{m}$ thickness of middle layer, high coupling efficiency(94%), and asymmetric vertical waveguides with n$_{u}$ = 1.522, n$_{l}$ = 1.51. We implemented vortical asymmetric thermo-optic modulator with lower inverted rib waveguide and upper slab waveguide. In the 600Hz bandwidth and 4.5㎽ input power, the extinction ratio of the mode was 17㏈ with an insertion loss of 4.5㏈.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.24 no.4
• /
• pp.439-447
• /
• 2011

Longitudinal cracks due to traffic truck loadings that are caused by local deformations of steel orthotropic bridge decks are sometimes observed in the wearing surface. So, underlying causes of the longitudinal pavement crack induced by structural behaviors of steel decks are investigated in this study. For this purpose, The rational finite element model of the steel deck and the pavement having the box girder is developed and a parametric study is performed by varying thickness or elastic modulus ratios of both the steel deck plate and the pavement. As a result, a large tensile strain above the webs of the u-rib and the box girder, which becomes the main cause of the cracks of the pavement, is detected from variation of the normal strain component of the wearing surface in the transverse direction.

• Asian-Australasian Journal of Animal Sciences
• /
• v.31 no.12
• /
• pp.1923-1929
• /
• 2018

Objective: This study was conducted to investigate the correlation between blood components and carcass traits, and to find the biomarkers related to meat quality and quantity in Hanwoo steers. Methods: One hundred twenty-six Hanwoo steers (8 to 9 months of age, body weight of $185.6{\pm}24.38kg$) were used to find the correlation between blood compositions and carcass traits. The steers were fed concentrate and rice straw (30 steers) or total mixed rations (96 steers) during the whole experimental period. Blood samples were collected from the jugular vein at the growing (8 to 12 months), fattening (13 to 23 months) and finishing phases (24 to 30 months). Steers were slaughtered at 30 to 31 months of age (body weight of $701.6{\pm}60.45kg$) and the carcass traits were evaluated. Blood metabolites and hormones were analyzed and the correlation coefficients and regression equations with carcass traits were determined. Results: Average concentrations of retinol, leptin and insulin were 1.10 IU, 30.34 ng, and 35.35 ng per mL of blood plasma, respectively. Retinol has negative correlations (p<0.01) with insulin and leptin. Blood insulin and total protein decreased with the age of steers, but retinol, aspartic acid transaminase (AST), glucose, cholesterol and triglyceride increased. In the finishing phase, significant (p<0.01) negative correlations occurred between blood retinol content and marbling score, and between blood AST content and longissimus muscle area of 13th rib, and the following regression equations were obtained: Marbling score $(1-9)=-0.009{\times}retinol(IU/100mL)+9.125$ ($R^2=0.643$), Longissimus muscle area $(cm^2)=-0.250{\times}AST(U/L)+112.498$ ($R^2=0.450$). Conclusion: It is possible to make highly marbled beef by controlling the blood retinol content during the fattening and finishing phases of Hanwoo steers. Accordingly, blood retinol and AST could be biomarkers for determining beef quality and quantity, respectively, prior to slaughter.

• Food Science of Animal Resources
• /
• v.24 no.2
• /
• pp.108-114
• /
• 2004

In a trial involving 72 pigs, the effects of market weight and gender on the carcass and pork quality characteristics were investigated. A total of 72 pigs were divided into 3 groups(95-104, 105-110 or 111-120kg), market weight was assigned to 2 gender group (gilt or boar). The carcass characteristics (carcass weight, backfat thickness or grades) were determined on those carcass, longissimus muscle was removed from each left side at 5th to 13th rib and meat qualities were evaluated. The carcass weight and backfat thickness of pigs slaughtered at 111-120kg were increases than the other weights. The carcass grade of pigs slaughtered at 105-110kg had higher then at pigs slaughtered 94-104kg. Compared with boars, gilts carcass had higher in carcass weight and backfat fat. The pH$\_$u/, drip loss and cooking loss tended to similar for market weight and gender, meat of boars had higher shear force values than gilts (p＜0.05). The meat color tended to similar for market weight and gender. The total myoglobin content of gilts slaughtered at 95-104kg and boars slaughtered at 111-120kg had higher than the other weight and gender. The meat of gilts had higher springiness and brittleness than boars (p＜0.05). These results imply that the carcass characteristics (carcass weight and backfat thickness) could be affected by market weight and gender, meat of gilts was improved the shear force values and texture properties when compared to boars.