• Journal of Mechanical Science and Technology
• /
• v.15 no.3
• /
• pp.403-409
• /
• 2001

The main objective of the present study is to perform an experimental evaluation of five existing correlations for the subchannel pressure drop analysis of a wire-wrapped fuel assembly. For this purpose, a series of water experiments have been performed using a helical wire-wrapped 19-pin fuel assembly for various test parameters. Four different test sections with different pitch to rod diameter ratios (P/D) and wire lead length to rod diameter ratios (H/D) have been fabricated. A series of pressure drop measurements were made to obtain friction factors for these four test sections. The new data along with existing data are used to evaluate existing correlations. Both the original and the simplified Cheng and Todreas correlations give the best agreement with experimental data for all flow regions.

• Steel and Composite Structures
• /
• v.3 no.3
• /
• pp.213-229
• /
• 2003

A high precision shear deformable triangular element has been proposed for free vibration analysis of composite trapezoidal plates. The element has twelve nodes at the three sides and four nodes inside the element. Initially the element has fifty-five degrees of freedom, which has been reduced to forty-eight by eliminating the degrees of freedom of the internal nodes through static condensation. Plates having different side ratios (b/a), boundary conditions, thickness ratios (h/a=0.01, 0.1 and 0.2), number of layers and fibre angle orientations have been analyzed by the proposed shear locking free element. Trapezoidal laminate with concentrated mass at the centre has also been analyzed. An efficient mass lumping scheme has been recommended, where the effect of rotary inertia has been included. For validation of the present element and formulation few results of isotropic trapezoidal plate and square composite laminate have been compared with those obtained from open literatures. The numerical results for composite trapezoidal laminate have been given as new results.

• Proceedings of the KSPS conference
• /
• 2005.11a
• /
• pp.185-188
• /
• 2005

We presents a new method for the measurement and analysis of the volume of the vocal tract using 3D magnetic resonance image. The relative ratios of volume A, B, and C, which are divided by the 2constriction points formed on the horizontal and vertical plane in vocal tract, take a decisive role indiscriminating Korean monophthong. Together with Fl-F2 and the minimum cross sectional area in the vocal tract, the relative ratios of the regional volumes were proved to be significant parameter in statistic viewpoint.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2011.05a
• /
• pp.41-42
• /
• 2011

In this study, VA/E/MMA-modified mortars with nitrite-type hydrocalumite were prepared with various calumite contents and polymer binder-ratios, and tested for chloride ion penetration, carbonation and drying shrinkage. As a result, the chloride ion penetration and carbonation depths were somewhat increased with calumite contents, but those were remarkably decreased depending on the polymer-binder ratios. The 28-d drying shrinkage showed a tendency to increase with polymer-binder ratios and calumite contents. VA/E/MMA-Modified mortars with a calumite of 10 % were dissatisfied with KS requirements. Accordingly, a calumite content of 5 % for the VA/E/MMA-modified mortars with calumite is recommended.

• Journal of the Korean Wood Science and Technology
• /
• v.10 no.4
• /
• pp.38-52
• /
• 1982

The effect of propylene oxide, butylene oxide, furan resin, and vinylpyrrolidinone in controlling wood dimensional stability have been examined. Wood in the green or ovendry condition was treated with various chemical treatments using a vacuum-pressure procedure, and treated specimens were tested for tangential sweelling, moisture gain, and changes in sorption hysteresis. Results' indicate that propylene oxide, and butylene oxide enhanced with the crosslin king agent trimethylol propane trimethacrylate and applied to ovendry wood were the most efficient chemical treatments in controlling tangential sweeling caused by liquid water or water vapor, and in reducing water vapor adsorption. The sorption behavior of treated wood as depicted by the ratios of sorption was "very favorable" in most instances. In the particular case of furan resin treatments, ratios of sorption were improved from 25 to 100 percent as compared to those of untreated wood.

• Korean Journal of Computational Design and Engineering
• /
• v.12 no.2
• /
• pp.109-117
• /
• 2007

Three-dimensional mesh models have been widely used in various applications such as simulations, animations, and e-catalogs. In such applications the normal vectors of mesh models are used mainly for shading and take up the major portion of data size and transmission time paper over networks. Therefore a variety of techniques have been developed to compress them efficiently. In this paper, we propose the MOEC (Modified Octree Encoding Compression) algorithm, which allow multi lever compression ratios for 3D mesh models. In the algorithm, a modified octree has nodes representing their own positions and supporting a depth of the tree so that the normal vectors are compressed up to levels where the shading is visually indistinguishable. This approach provides efficient in compressing normals with multi-level ratios, without additional encoding when changing in compression ratio is required.

• Archives of Pharmacal Research
• /
• v.19 no.1
• /
• pp.23-29
• /
• 1996

Changes in dopaminergic activities were investigated after the intracerebroventricular (icv) administration of ethylcholine aziridium (AF64A) in rats. The levels of dopamine (DA) and metabolites, the activities of tyrosine hydroxylase (TH) and monoamine oxidase (MAO), and the specific binding sites of dopamine receptros in striata, hippocampus, and frontal cortex were assessed 6 days after the AF64A treatment with 3 nmol/each ventrcle. In frontal cortex, the levels of DA and metabolities were significantly decreased without changes in metabolites/DA ratios in the AF64A-treated groups. In contrast, the ratios of metabolites/DA were significantly decreased in striatum and hippocampus in the AF64A treatment. The activity of TH in frontal cortex was significantly decreased. However, that in other areas was not changed. Also the activity of MAO-A was not changed in the studied brain regions. However, the activity of MAO-B in striatum was significantly increased with no change in other areas. The specific binding sites of dopamine D1 and D2 receptors were increased in AF64A-treated frontal cortex. However, those were not changed in striatum and hippocampus except the small decreased specific binding sites of dopamine D-1 receptors in striatum after AF64A treatment. These results indicate that the dopaminergic activity was altered in AF64A treatment. Furthermore, it suggest that the decreased dopaminergic activities in each brain regions might be differently affected by AF64A treatment.

• Steel and Composite Structures
• /
• v.29 no.4
• /
• pp.557-567
• /
• 2018

Cylindrical shell structures buckle at service loads which are much lower than their associated theoretical buckling loads. The main source of this discrepancy is the presence of various imperfections which are created on the cylinder body during different processes as manufacturing, handling, assembling and machining. Many cylindrical shell structures are still designed against buckling based on the experimental data introduced by NASA SP-8007 as conservative lower bound curves. This study employed the numerical based Linear Buckling mode shape Imperfection (LBMI) method and modified it using a stochastic method to assess the effect of geometrical imperfections in more details on the buckling of cylindrical shells with and without the cutout. The comparison of results with those obtained from the numerical Simcple Perturbation Load Imperfection (SPLI) method for cylinders with and without cutout revealed a good correlation. The effect of two parameters of size and number of cutouts on the buckling load was investigated using the linear buckling and Modified LBMI methods. Results confirmed that in cylinders with a small cutout inserting geometrical imperfection using either SPLI or modified LBMI methods significantly reduced the value of the predicted buckling load. However, in cylinders with larger cutouts, the effect of the cutout is dominant, thus considering geometrical imperfection had a minor effect on the buckling loads predicted by both SPLI and modified LBMI methods. Furthermore, the modified LBMI method was employed to evaluate the combination effect of cutout numbers and size on the buckling load. It is shown that in small cutouts, an increasing in the cutout size up to a certain value resulted in a remarkable reduction of the buckling load, and beyond that limit, the buckling loads were constant against D/R ratios. In addition, the cutout number shows a more significant effect on decreasing the buckling load at small D/R ratios than large D/R ratios.

• Journal of Preventive Medicine and Public Health
• /
• v.41 no.6
• /
• pp.407-412
• /
• 2008

Objectives: The purpose of this study was to evaluate the relationship of nonalcoholic fatty liver and cardiovascular risk factors. Methods: This study was conducted to investigate the association of nonalcoholic fatty liver and cardiovascular risk factors for adult men (n=2976) and women (n=2442) who were over 19 years old, after excluding the HBsAg(+) or anti-HCV(+) patients and the men and women with increased alcohol intake (men: 40g/week, women: 20g/week). Results: Compared with the normal liver subjects, the nonalcoholic fatty liver subjects showed a significantly increased frequency of abnormal systolic blood pressure (${geq}120mmHg$), fasting blood sugar (${\geq}100mg/dL$), total cholesterol ($({\geq}200 mg/dL$), triglyceride ($({\geq}150mg/dL$), high density lipoprotein cholesterol (<40 mg/dL), low density lipoprotein cholesterol ($({\geq}130g\; m/dL$) and abdominal obesity in men, and all these measures were significantly increased in the women except for abnormal HDL cholesterol. After adjusting for the body mass index, age, smoking, exercise and a nonalcoholic liver, the odds ratios of an abnormal waist hip ratio were 1.35(95% Confidence Interval=1.05-4.72) in the mild fatty liver, 1.61 (1.19-2.18) in the moderate fatty liver, 2.77(1.57-4.92) in the severe fatty liver compared with a normal liver. The adjusted odds ratios for abnormal fasting blood sugar were 1.26(1.03-1.53) in the mild fatty liver, 1.62(1.27-2.06) in the moderate fatty Iiver and 1.77(1.12-2.78) in the severe fatty liver. The adjusted odds ratios for abnormal triglyceride were 1.38(1.11-1.72) in the mild fatty liver, 1.73(0.33-2.24) in the moderate fatty liver and 1.91 (1.17-3.10) in the severe fatty liver of men. Adjusted odds ratios for abnormal triglyceride were 1.50(1.04-2.15) in mild, 1.71(1.07-2.68) in moderate, 1.81(0.69-4.38) in severe fatty liver of women. Conclusions: The nonalcoholic fatty liver subjects had more cardiovascular risk factors compared with the normal liver subjects. Thus, prevention and treatment of the nonalcoholic fatty liver is necessary by lifestyle modifications such as restriction of alcohol intake, no smoking, exercise and adequate eating habits.

• Nuclear Engineering and Technology
• /
• v.51 no.5
• /
• pp.1355-1364
• /
• 2019

A recently published nuclear forensics methodology for source discrimination of separated weapons-grade plutonium utilizes intra-element isotope ratios and a maximum likelihood formulation to identify the most likely source reactor-type, fuel burnup and time since irradiation of unknown material. Sensitivity studies performed here on the effects of random measurement error and the uncertainty in intra-element isotope ratio values show that different intra-element isotope ratios have disproportionate contributions to the determination of the reactor parameters. The methodology is robust to individual errors in measured intra-element isotope ratio values and even more so for uniform systematic errors due to competing effects on the predictions from the selected intra-element isotope ratios suite. For a unique sample-model pair, simulation uncertainties of up to 28% are acceptable without impeding successful source-reactor discrimination. However, for a generic sample with multiple plausible sources within the reactor library, uncertainties of 7% or less may be required. The results confirm the critical role of accurate reactor core physics, fuel burnup simulations and experimental measurements in the proposed methodology where increased simulation uncertainty is found to significantly affect the capability to discriminate between the reactors in the library.