• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.965-968
• /
• 2005

Roll drafting operation causes variations in the linear density of bundles because the bundle flow cannot be controlled completely by roll pairs. Defects occurring in this operation bring about many problems successively in the next processes. In this paper, we attempt to analyze the draft dynamics and the linear density irregularity based on the governing equation of a bundle motion that has been suggested in our previous studies. For analyzing the dynamic characteristics of the roll drafting operation, it is indispensable to investigate a transient state in time domain before the bundle flux reaches a steady state. However, since governing equations of bundle flow consisting of continuity and motion equations turn out to be nonlinear, and coupled between variables, the solutions for a transient state cannot be obtained by an analytical method. Therefore, we use the Finite Difference Method(FDM), particularly, the FTBS(Forward-Time Backward-Space) difference method. Then, the total equations system yields to an algebraic equations system and is solved under given initial and boundary conditions in an iterative fashion. From the simulation results, we confirm that state variables show different behavior in the transient state; e.g., the velocity distribution in the flow field changes more quickly the linear density distribution. During a transient flow in a drafting zone, the output irregularity is influenced differently by the disturbances, e.g., the variation in input bundle thickness, the drafting speed, and the draft ratio.

• Ocean and Polar Research
• /
• v.35 no.1
• /
• pp.27-37
• /
• 2013

The western coast of Anmyeondo is open toward the Yellow sea and the northern and southern coasts are sandy and have simple coastlines. In this study, we investigated the spatial distribution and community structure of the macrobenthos that inhabit the sandy shore of Anmyeondo. For the study, we chose 8 sites encompassing 44 stations. In total, we have recorded 62 species, and collected 747 inds./$m^2$ on average. Zonation pattern did not appear because the mean grain size and organic contents of the study sites were similar among the macrobenthos. Polychaetes were most frequently recorded, but amphipods appeared in higher mean density. Macrobenthic community is classified into 3 groups largely based on the density difference among the dominant species and the groups were not influenced by environmental factors. The aggregated distribution of macrobenthos did not show a clear regional spatial difference but exhibited classification pattern emphasizing the density difference of the dominant species. The sandy shores of Anmyeondo are relatively more influenced by waves compared to other regions and the sediment moves more due to strong winds, etc. at low tide. We presume that the movement of sediment resulted in a relatively even sedimentary environment and consequently weakened environmental variables that change with the tide level. We concluded that the macrobenthic community does not show the zonation pattern in the sandy shores of Anmyeondo due to such influences.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.23 no.2
• /
• pp.426-432
• /
• 2009

The overall purpose of this study was to investigate the effects of level of isoflavones supplementation on bone metabolism in osteoporosis rats. The effects of level of isoflavones supplementation on calcium and osteocalcin blood level, femur/body weight, bone mineral density(BMD) and bone strength were inspected in this study. This study classified 28 of 12 weeks-old male Sprague Dawley rats which have osteoporosis caused by ovariectomy into four groups of 7 rats and made the subjects medicated them isoflavone. Group I was non-treatment after osteoporosis(control); Group II was low-dose isoflavone(20 mg/kg) feeding after osteoporosis; Group III was middle-dose isoflavone(40 mg/kg) feeding after osteoporosis; Group IV was high-dose isoflavone(80 mg/kg) feeding after osteoporosis; In the calcium and osteocalcin level as one of bone formation indexes, there was a statistically significant difference between the group II, III, IV compared to group I. In respect to the femur/body weight, there was a statistically significant difference between the group II, III, IV compared to group I. In the bone mineral density and bone strength test, there was a statistically significant difference between the group II, III, IV compared to group I. The above results suggests that isoflavone medicated is effective to prevention and treatment of osteoporosis.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.54 no.4
• /
• pp.137-145
• /
• 2012

Sand is one of the essential materials used for social infrastructure construction such as embankment, landfill and backfill. It was known that mechanical properties and shear strength of sand are closely related to relative density. Therefore it is very important to determine accurate relative density. In this study, Portable Cone Penetration Tester (PCPT) was used to estimate the relative density and the internal friction angle of sand. PCPT cone-tip resistance ($q_c$) was measured changing the relative density of the two soil samples.Standard sand (JMJ) and Busan sand (BS). Also, a direct shear test was performed to investigate relationship between relative density and internal friction angle. The size and shape of soil particles were confirmed by using Scanning Electron Microscope (SEM). As a result, the log value of $q_c$ was linearly correlated with relative density and internal friction angle. In particular, the internal friction angle of BS sample was greater than that of JMJ, which was due to difference of the shape and mean size of particles. This result shows that it is important to determine the shape and size of particles as well as relative density to define mechanical property of sand. Through this study, it can be more effectively and conveniently to investigate relative density and shear strength of sand by using PCPT in situ.

• Asian-Australasian Journal of Animal Sciences
• /
• v.13 no.7
• /
• pp.929-934
• /
• 2000

Optimum stand density of alfalfa (Medicago sativa L.) varies with locations and climates. Stand density is one of the factors that determines herbage yield, forage quality and persistence of alfalfa. As establishment costs increase, the question arises whether present population densities are optimum for obtaining maximum herbage yield and forage quality. The objectives of this study were: 1) to determine the optimum plant density for highest herbage yield and forage quality for the dehydrated alfalfa industry under Edmontons climatic conditions in Alberta, Canada; 2) to compare herbage yield and forage quality of the cultivars 'Algonquin' and 'Vernal' grown at a range of stand densities. Alfalfa seedlings of both cultivars were either transplanted at spacings of 6, 10, 15 and 25 cm or direct seeded at the 4.5 cm plant spacings, providing population densities of 494, 278, 100, 45 and $16plants/m^2$. The experimental design was a randomized complete block with a split-plot arrangement having three replicates; the main plots consisted of two alfalfa cultivars Algonquin and Vernal, and the sub-plots were the five population densities. The cultivar Vernal had significantly higher annual yield than did the cultivar Algonquin. There was no significant effect of plant density on herbage yield. There was no difference in crude protein (CP) between the two cultivars. At the first cut, there was a significant quadratic effect of plant density on CP content and the greatest CP occurred at the 100 plants/m2 density. Crude protein was not affected by plant density at the second cut. Acid detergent fiber (ADF) and neutral detergent fiber (NDF) were not affected by plant density. The cultivar Algonquin usually had a lower ADF and NDF than cultivar Vernal. In conclusion, high population densities ($278plants/m^2$ or more) of alfalfa did not improve herbage yield and forage quality compared with low plant population densities ($100plants/m^2$ or less) of alfalfa.

• Journal of the Korean Society of Radiology
• /
• v.12 no.3
• /
• pp.403-407
• /
• 2018

Currently, the highest cancer death rate in Korea is lung cancer, which is a typical cancer that is difficult to detect early. Low-dose chest CT is being used for early detection, which has a greater lung cancer diagnosis rate of about three times than regular chest x-ray images. However, low-dose chest CT not only significantly reduces image resolution but also has a weak signal and is sensitive to noise. Also, air filled lungs are low-density organs and the presence of noise can significantly affect early diagnosis of cancer. This study used Visual C++ to set a circle inside a large circle with a density of 2.0, with a density of 1.0, which is the density of water, in which five small circle of mathematics have different densities. Gaussian noise was generated by 1%, 2%, 3%, and 4% respectively to determine the effect of noise on the mean value, the standard deviation value, and the relative noise ratio(SNR). In areas where the density difference between the large and small circles was greatest in the event of 1 % noise, the SNR in the area with the greatest variation in noise was 4.669, and in areas with the lowest density difference, the SNR was 1.183. In addition, the SNR values can be seen to be high if the same results are obtained for both positive and negative densities. Quality was also clearly visible when the density difference was large, and if the noise level was increased, the SNR was reduced to significantly affect the noise. Low-density organs or organs in areas of similar density to cancers, will have significant noise effects, and the effects of density differences on the probability of noise will affect diagnosis.

• Journal of Veterinary Clinics
• /
• v.28 no.5
• /
• pp.510-515
• /
• 2011

This study was performed to quantitatively assess the normal lung volume and density according to the position by multi-detector computed tomography (MDCT) in dogs. Helical CT of the thorax was performed on 4 different positions with dorsal, left lateral, right lateral and ventral recumbency in 6 Pekingese and 6 Maltese dogs. During CT scanning, dogs were kept hyperventilated. Through the 3-dimensional reconstruction of CT images, the lung parameters were measured as the volume and density of the left, right including accessory lobe, and total lung. 3D images represented the different lung shape between Pekingese and Maltese dogs. Their difference of total lung volume and total lung density was not significant on the each position in both breeds. Right lung volume was significantly higher than left. The difference of left and right volume was $66.91{\pm}25.1$ ml. Linear relationship was shown between body weight and lung volume of ventral recumbency position. The dependent lung had higher density and lower volume than nondependent lung in both breed dogs. The volume of nondependent lung was not changed compared with the volume on ventral or dorsal recumbency. The total lung volume measured with MDCT is correlated with the lung density, and the lung density is useful to predict the normal total lung volume.

• Journal of the Korean Society of Radiology
• /
• v.17 no.6
• /
• pp.929-937
• /
• 2023

Human equivalent phantoms manufactured using 3D printers are cheaper and can be manufactured in a short time than conventional human phantoms. However, many phantoms are manufactured with less than 100 % of Infill Density, one of the 3D printer output setting variables. Therefore, this study compared the Bone Phantom CT number, which differs from the ratio of five Infill Density produced using a 3D printer, to the CT number of the actual human body Bone. In addition, the usefulness of the manufactured phantom was evaluated by producing a 100 % elbow joint phantom with Infill Density and setting the Infill Density to 100 % through CT number comparison for each tissue on computed tomography (CT). As a result, the Bone Phantom printed with 100 % Infill Density did not show the most statistically significant difference from the CT number value of the actual human Bone, and the CT number of each tissue did not show a statistically significant difference from the CT number value of each tissue of the actual human elbow joint.

• Korean Journal of Environment and Ecology
• /
• v.34 no.5
• /
• pp.425-435
• /
• 2020

This study aims to investigate the impact of the physical structure, such as altitude, slope gradient, slope direction, and topographical structure, and the vegetation pattern, such as existing vegetation, diameter of breast height (DBH), and crown density, on climate. The analysis results showed the significant difference in relative humidity, wind speed, and solar radiation at varying altitudes, the significant difference in all climate factors except for the wind speed at varying slope gradient, and significant difference in temperature and relative humanity at varying slope direction. The topographic structures were divided into valleys, slopes, and ridges. They were found to differ in relative humidity. However, the differences between constant trends and types were found to be insignificant concerning temperature, wind speed, and solar radiation. Significant differences in temperature, relative humidity, and wind speed were recorded with changing existing vegetation. The DBH showed a significant difference in temperature, wind speed, and solar radiation. The crown density showed a significant difference in temperature and solar radiation. The result of the relationship analysis for the analysis of the effect of vegetation pattern and physical structure on the meteorological environment showed that temperature was affected by slope gradient, slope direction, DBH, and crown density. The relative humidity was correlated with the altitude, slope gradient, slope direction, and topological structure in physical structure and the existing vegetation and crow density in vegetation pattern. The wind speed was correlated with the altitude, existing vegetation, and DHB, and the solar radiation was correlated with the slope gradient, DHG, and crown density. The crown density was the most overall significant factor in temperature, relative humidity, and solar radiation, followed by the slope gradient. DBH was also found to be highly correlated with temperature and solar radiation and significantly correlated with wind speed, but there was no statistically significant correlation with relative humidity.

• Preventive Nutrition and Food Science
• /
• v.1 no.2
• /
• pp.234-238
• /
• 1996

The purpose of this study was to determine whether vitamin {TEX}$B_{6}${/TEX} deficiency and age affect the blood cho-lesterol profile in exercising rats. Fifty four rats were fed either a viramin {TEX}$B_{6}${/TEX} deficient dief(-{TEX}$B_{6}${/TEX}) of a control diet(+{TEX}$B_{6}${/TEX}) for 6 weeks, then subdivided into 3 groups:non-exercise group(NE), exercise and sacrifice group(ES), exercise and recuperation group(ER). ES group was exercised in treadmill({TEX}$10^{o}${/TEX}, 0.5~0.8km/h) for 2 hours and sacrifice. ER group was recuperated three days with respective diet after exercise. At week 3 and 6, and level of plasma total cholesterol(TC), high density lipoprotein cholesterol(HDL_C) and low density lipoprotein cholesterol(LDL_C) were compared. In NE group, there was no difference in the levels of TC, HDL_C and LDL_C between +{TEX}$B_{6}${/TEX} rats and -{TEX}$B_{6}${/TEX} rats. The plasma levels of TC and LDL_C of 6 weeks were higher than those of 3 weeks and on difference in HDL_V between 3 weeks rats and 6 weeks rats. In ES group, there was also no difference in the levels of TC, HDL_C and LDL_C between +{TEX}$B_{6}${/TEX} rats and -{TEX}$B_{6}${/TEX} rats and there was no difference in TC, LDL-cholesterol between 3 weeks rats and 6 weeks rats. The level of HDL_C pf 6 weeks was lower than that of 3 weeks rats. In ER group, there was no difference in the levels of TC and LDL_C not only between +{TEX}$B_{6}${/TEX} rats and-{TEX}$B_{6}${/TEX} rats but also between 3 weeks rats and 6 weeks rats. The level of HDL_C was lower in -{TEX}$B_{6}${/TEX} rats than in +{TEX}$B_{6}${/TEX} rats and higher in 6 weeks rats than in 3 weeks rats. These results suggest that vitamin {TEX}$B_{6}${/TEX} deficiency may affect the HDL_C during exercise and after recuperation. The desirable effect of exercise on plasma Cholesterol profile is strengthened in adult age than young age.