• Journal of Mechanical Science and Technology
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• v.14 no.12
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• pp.1386-1395
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• 2000

The mear field structure of round turbulent jets with initially asymmetric velocity distributions is investigated experimentally. Experiments are carried out using a constant temperature hot-wire anemometry system to measure streamwise velocity in the jets. The measurements are undertaken across the jet at various streamwise stations in a range starting from the jet exit plane and up to a downstream location of twelve diameters. The experimental results include the distributions of mean and instantaneous velocities, vorticity field, turbulence intensity, and the Reynolds shear stresses. The asymmetry of the jet exit plane was obtained by using circular cross-section pipes with a bend upstream of the exit. There pipes used here include a straight pipe, and 90 and 160 degree-bend pipes. Therefore, at the upstream of the upstream of the pipe exit, secondary flow through the bend mean streamwise velocity distribution could be controlled by changing the curvature of pipes. The jets into the atmosphere have two levels of initial velocity skewness in addition to an axisymmetric jet from a straight pipe. In case of the curved pipe, a six diameter-long straight pipe section follows the bend upstream of the exit. The Reynolds number based on the exit bulk velocity is 13,400. The results indicate that the near field structure is considerably modified by the skewness of an initial mean velocity distribution. As the skewness increases, the decay rate of mean velocity at the centerline also increases.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.3
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• pp.494-500
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• 1997

This study was conducted to investigate the effect of acorn extracts on the antioxidative enzyme system. Male Sprague-Dawley rats(110$\pm$10g) were fed on containing normal and high fat diets. They were orally administrated (0.02g/100g B.W) of acorn ethylacetate-extract and water-extract at the same time once a day, respectively. Net weight gain and feed efficiency ratio were increased in high fat diet groups and decreased by acorn extracts administration. The effect of acorn extracts on hepatic glutathione peroxidase(GSH-Px), glutathione S-transferase(GST) and catalase activities did not show significancy in normal fat diet groups. GST and catalase activities and lipid peroxidation content(LPO) were significantly increased in high fat diet groups and this increment were decreased by acorn extracts administration. However GSH-Px activity and GSH content were decreased in high fat diet groups but increased by acorn extracts administration. The activities of lactate dehydrogenase(LDH), alkaline phosphatase(ALP) and aminotransferase in serum were significantly increased in high fat diet group but these increment reduced in acorn extracts administration groups. These results indicate that acorn extracts could improve the liver function and prevent the metabolic diseases by hyperlipidemia.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.1
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• pp.109-112
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• 2006

The objective of this study was to evaluate the combined effects of lactoperoxidase system (LPS), thermal treatment and storage time on total microflora and psychrotrophs counts of the marinated broiler drumsticks. A marinade that contained acetic acid (1%) and salt (3%) with pH adjusted to 4 was developed as a standardized marinade. Drumsticks were marinated with various LPS levels, combined with thermal treatment (4 or $58^{\circ}C$ for 2 min), and then stored at $4^{\circ}C$ for 18 h. The microbial counts of the samples were measured after 0, 2, 4 and 7 days of storage for drumsticks held at $4^{\circ}C$. The results indicate that adding LPS at the level of 1 unit ($1{\mu}g/ml$ LP, 5.9 mM KSCN, and 2.5 mM $H_2O_2$) significantly (p<0.05) decreased the total microflora and psychrotrophs counts of the marinated broiler drumsticks. In addition, samples treated with a thermal treatment ($58^{\circ}C$ for 2 min) had significantly (p<0.05) lower microbial counts when compared with the control.

• Journal of the Korean Chemical Society
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• v.15 no.4
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• pp.177-181
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• 1971

Free radicals of lysozyme produced by $Ti-H_2O_2$ system were studied in aqueous solution at room temperature using ESR with a continuous flow-mixing. The spectra, each consisting of a doublet with 5.5 G splitting and a broad resonance covering 80 G splitting are closely similar in shape to that for solid irradiated in vacuum at $77^{\circ}K$ and observed at room temperature immediately on warming. The result is assumed to indicate that the secondary protein radical components formed within 0.01 second, dead time of the mixing chamber, and initiated by hydrogen atom abstraction at ${\alpha}$-carbon atom of peptide chain in liquid solution at room temperature are identical to those resulting from the initial formation of a mixture of positive holes and negative ions by ionization processes as well as radical fragments by the rupture of chemical bonds in the solid during similar time at the same temperature. A broad resonance is observed with considerable amplitude on the high field side of the doublet, which is quite dissimilar to the spectra of irradiated solid lysozyme. This resonance was tentatively attributed to the polypeptide free radical in which unpaired electrons are localized on side chain.

• Journal of the Korean Society for information Management
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• v.25 no.4
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• pp.67-85
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• 2008

The purposes of this study are to examine the factors influencing the user satisfaction of knowledge management system(KMS) and the influence of the user satisfaction on the performance, and to search the strategies for effective KMS operating. The results of covariance structural analyses indicate that the factors-knowledge quality and KMS quality significantly influence the user satisfaction. User satisfaction also significantly affects the performance. Based on the results, this study discusses the potential implications for the strategies of KMS implementing to improve the user satisfaction and performance.

• Agricultural and Biosystems Engineering
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• v.6 no.1
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• pp.1-7
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• 2005

Assessing health condition of crop in the field is one of core operation in precision fanning. A sensing system was proposed to remotely detect the crop health condition in terms of SP AD readings directly related to chlorophyll contents of crop using a multispectral camera equipped on ground-based platform. Since the image taken by a camera was sensitive to changes in ambient light intensity, it was needed to convert gray scale image data into reflectance, an index to indicate the reflection characteristics of target crop. A reference reflectance panel consisting of four pieces of sub-panels with different reflectance was developed for a dynamic calibration, by which a calibration equation was updated for every crop image captured by the camera. The system performance was evaluated in a field by investigating the relationship between com canopy reflectance and SP AD values. The validation tests revealed that the com canopy reflectance induced from Green band in the multispectral camera had the most significant correlation with SPAD values $(r^2=0.75)$ and NIR band could be used to filter out unwanted non-crop features such as soil background and empty space in a crop canopy. This research confirmed that it was technically feasible to develop a ground-based remote sensing system for assessing crop health condition.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.126-130
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• 1997

In the development of the totally implantable artificial heart (TAH), the information of the preload condition is important to ind appropriate condition or the automatic control of the heart. Our TAH configuration consists of two artificial ventricles, and brushless DC motor within actuator. The pressure between ventricles could indicate the preload condition during the TAH operation. If we can measure accurately inspite of the noise induced from TAH and environmental condition. We suggested integrating a feedback loop to remove an unexpected DC drift. NPI 19-series Nova sensor was used which could measure pressure in gas and liquid. This method and sensor enabled us to develop the pressure transducer compact so (that) the systems can be implanted with TAH into patient. This system has been verified in vitro and in vivo test. This results showed that the output waveform of this system was stable irrespective of animal condition.

• The Korean Journal of Physiology and Pharmacology
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• v.24 no.4
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• pp.319-328
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• 2020

High fructose intake induces hyperglycemia and hypertension. However, the mechanism by which fructose induces metabolic syndrome is largely unknown. We hypothesized that high fructose intake induces activation of the renin-angiotensin system (RAS), resulting in hypertension and metabolic syndrome. We provided 11-week-old Sprague-Dawley rats with drinking water, with or without 20% fructose, for two weeks. We measured serum renin, angiotensin II (Ang II), and aldosterone (Aldo) using ELISA kits. The expression of RAS genes was determined by quantitative reverse transcription polymerase chain reaction. High fructose intake increased body weight and water retention, regardless of food intake or urine volume. After two weeks, fructose intake induced glucose intolerance and hypertension. High fructose intake increased serum renin, Ang II, triglyceride, and cholesterol levels, but not Aldo levels. High fructose intake increased the expression of angiotensinogen in the liver; angiotensin-converting enzyme in the lungs; and renin, angiotensin II type 1a receptor (AT1aR), and angiotensin II type 1b receptor (AT1bR) in the kidneys. However, expression of AT1aR and AT1bR in the adrenal glands did not increase in rats given fructose. Taken together, these results indicate that high fructose intake induces activation of RAS, resulting in hypertension and metabolic syndrome.

• Research in Plant Disease
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• v.24 no.2
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• pp.162-169
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• 2018

The GacS/GacA system in the root colonizer Pseudomonas chlororaphis O6 is a key regulatory system of many traits relevant to the plant probiotic nature of this bacterium. The work in this paper elucidates proteins using proteomics approach in P. chlororaphis O6 under the control of the cytoplasmic regulatory protein, GacA. A gacA mutant of P. chlororaphis O6 showed loss in production of phenazines, acyl homoserine lactones, hydrogen cyanide, and protease, changes that were associated with reduced in vitro antifungal activity against plant fungal pathogens. Production of iron-chelating siderophore was significantly enhanced in the gacA mutant, also paralleling changes in a gacS mutant. However, proteomic analysis revealed proteins (13 downregulated and 7 upregulated proteins in the mutant compared to parental strain) under GacA control that were not apparent by a proteomic study of a gacS mutant. The putative identity of the downregulated proteins suggested that a gacA mutant would have altered transport potentials. Notable would be a predicted loss of type-VI secretion and PEP-dependent transport. Study of mutants of these GacA-regulated proteins will indicate further the features required for probiotic potential in this rhizobacterium.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.124-129
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• 2011

An improved NDIF method is introduced to efficiently extract eigenvalues of two-dimensional, arbitrarily shaped acoustic cavities. The NDIF method, which was developed by the authors for the eigen-mode analysis of arbitrarily shaped acoustic cavities, membranes, and plates, has the feature that it yields highly accurate eigenvalues compared with other analytical methods or numerical methods (FEM and BEM). However, the NDIF method has the weak point that the system matrix of the NDIF method depends on the frequency parameter and, as a result, a final system equation doesn't take the form of an algebra eigenvalue problem. The system matrix of the improved NDIF method developed in the paper is independent of the frequency parameter and eigenvalues can be efficiently obtained by solving a typical algebraic eigenvalue problem. Finally, the validity and accuracy of the proposed method is verified in two case studies, which indicate that eigenvalues and mode shapes obtained by the proposed method are very accurate compared to the exact method, the NDIF method or FEM(ANSYS).