• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.7
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• pp.69-74
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• 2003

By employing vane tip concept, a new rotor blade (NRSB-I) has been designed to enhance the noise characteristics of BERP blade. Numerical analyses have been performed for hovering rotor and the results are compared with respect to those of original BERP blade. Although the thrust of designed rotor decreases by 6-7% due to cutout at the tip region, the results indicate that the actual performance loss is negligible because power reduction is greater than thrust loss. It is also found that aerodynamic fence is required at the outboard kink to obtain clearly separated twin-vortices because the vortex generated at kink is diffused during the convection over the blade surface.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.4
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• pp.99-104
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• 2003

This paper described the general dynamic point for rotor design and the design procedure of low vibration blade. Generally, rotor rotating natural frequencies are determined to minimize hub loads, blade vibration and to suppress ground resonance at rotor design stage. First, through rotor frequency diagram, natural frequencies must be far away from resonance point and rotating loads generated from blade can be transformed to non-rotating load to predict fuselage vibration. Vibration level was predicted at each forward flight condition by calculating cockpit's vertical acceleration transferred from non-rotating hub load assuming a fuselage as a rigid body. This design method is applied to design current Next-generation Rotor System Blade(NRSB) and will be applied to New Rotor which will be developed Further.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.2
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• pp.10-16
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• 2003

The unsteady supersonic flow over tandem cavities has been analyzed by the integration of Navier-Stokes equations with the k-$\varepsilon$ turbulence model. The unsteady flow is characterized by the periodicity due to the mutual relation between the shear layer and the internal flow in cavities. The upwind TVD scheme based on the flux vector split with the van Leer limiters is used. The results show the principal frequency is very reasonable. The principal frequency of the rear cavity due to the front cavity has been analyzed by the combination of the several aspect ratios of cavities. In the case of the front cavity of low aspect ratio, the frequencies of tandem cavities are almost same, because two shear layers developed from each cavity are mixed and developed to one shear layer. However, in the case of the front cavity of high aspect ratio, the characteristis of frequency are very different, because the second shear layer is developed in the diffused first shear layer.

• Journal of the Korea Convergence Society
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• v.8 no.5
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• pp.87-96
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• 2017

This study was carried out to provide basic data for prevention of death from injuries and traumas by analyzing the characteristics of length of hospital stay of patients with injuries and traumas, utilizing in-depth investigation data of discharged injuries. The study subjects were 233 patients discharged from January 1 to December 31 in 2014 whom the final treatment result was 'death' and the main diagnosis were injuries and accidental external causes(S00-T98). According to the research findings, the length of hospital stay of females was longer than that of males. Based on the main diagnosis, the longest length of hospital stay had complication of other internal prosthetic devices, implants and grafts(T85). In conclusion, it is necessary to develop a policy to identify the factors affecting the length of hospital stays of patients and to manage them intensively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.12
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• pp.1599-1606
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• 2011

It is possible to study the load characteristics of full-scale hingeless rotor with the changing of physical smallscaled configurations such as rectangular and paddle blades, and metal and composite hubs. In this study, a static test, and a ground and wind-tunnel test were carried out using small-scale rotor models. The static test was carried out to confirm structural stiffness, characteristics of inertia, natural frequency, and damping ratio of rotors, and the ground and wind-tunnel test was carried out to confirm the stability and aerodynamic characteristics under hovering and forward flight conditions. According to the test results, the vertical load in the case of a combination of a small composite hub with paddle blades was higher than that in the case of a metal hub with paddle blades at same condition. Further, it was confirmed that the restraint of the combination of composite hub can be more flexible than the metal hub for the motion of paddle blades.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.5
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• pp.1-9
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• 2003

Detailed flow of a shrouded tail rotor in hover is studied by using a compressible inviscid flow solver on unstructured meshes. The numerical method is based on a cell-centered finite-volume discretization and an implicit Gauss-Seidel time integration. Numerical simulation is made for a single blade attached to the center body and guide by the duct by imposing a periodic boundary condition between adjacent rotor blades. The results show that the performance of an isolated rotor without shroud compares well with experiment. In case of a shrouded rotor, correction of the collective pitch angle is made such that the overall performance matches with experiment to account for the uncertainties of the experimental model configuration. Details of the flow field compare well with the experiment confirming the validity of the present method.

• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.3
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• pp.662-672
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• 2009

Obesity has increased dramatically increased in recent days. It has resulted in obesity-associated diseases and metabolic syndromes including hyperlipidemia, diabetes and cardiovascular diseases. Our study was investigated to determine the antiobese effects of mixed 2 medicinal herbs (AR+AC) in rats fed high-fat diet with an abundance of carbohydrates. Two groups of male Sprague-Dawley rats were fed different diets during 8 weeks: normal diet containing 5% corn oil (w/w), high-fat diet containing 10% (w/w) lard plus 5% (w/w) corn oil (HF). And High-fat diet group was treated with saline or 100 mg/kg ARAC or 300 mg/kg ARAC (PO). Antiobese effect was evaluated by measuring the changes of body weight, adipose tissues weight. Also we examined levels of leptin, adiponectin and lipid profiles in serum. Finally we compared morphological change in adipocytes and hepatocytes between HF and ARAC group. Mixed combination of 2 medicinal herbs, but not alone, caused significant decrease in body weight, organ weight (liver, epididymal fat, and BAT) compared with control HF group. The ARAC group had markedly lower serum levels of adiponectin when compared with HF group. Also the epididymal white adipocyte size of ARAC group were diminished comparing to the HF group. These results suggest that the possibility of ARAC combination, as an antiobese formula, by suppression of body weight gain and increased lipid profiles.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3274-3279
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• 2009

The elutriation characteristics of particle size distribution were investigated in a gas-solid fluidized bed. Experiments were carried out with the mulit-sized particles of Gaussian distributions. The elutriation rate constant obtained from the experiment was correlated with the standard deviation of particle size and the dimensionless group of the velocity ratio. The standard deviation of pressure fluctuation, mean pressure, major frequency and power spectrum density function were calculated by pressure fluctuation properties. Size distribution of elutriated particles and pressure fluctuations were measured for the particle size distribution of particle system depended largrly on the size distribution. Characteristics of fluidization and elutriation were greatly influenced by the particle size distribution and these characteristics could be interpreted with pressure fluctuation properties.

• Journal of Korea Game Society
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• v.11 no.2
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• pp.105-114
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• 2011

In a game such as MMORPG, players often see occlusions between primary actors in a shot where shows a close quarter combat. This paper proposes an occlusion resolution technique(MOS) by grafting a medium shot technique and an over-shoulder shot technique to strengthen a confrontation structure. A medium shot technique sets 4 reference points at the up/down/left/right on the sphere of target. An over-shoulder shot technique is a technique of locating the reference points on the side variably. An occluder is replaced with 2 spheres. If a ray is emitted to a reference point from the camera point and intersects a sphere of occluder, it becomes a potential occlusion state. If so, we start to move the camera to the right or left of the occluder, keep moving it while new position of camera is in potential occlusion state, and stop its movement when the occlusion is resolved. Our experiments show that MOS technique consumes operational time of $13.7{\mu}s$ per shot on average, and that it resolves occlusions in 9.26% of ratio on average, and so doesn't have any effect on viewer's sight.

• The Journal of Korean Obstetrics and Gynecology
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• v.20 no.3
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• pp.91-110
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• 2007

Purpose : These experiments were undertaken to evaluate the effect of administration of Palmultang on ovarian functions and differential gene expressions related cell viabilities caspase-3, MAPK and MPG in female mice. Materials and Methods : We administered the Palmultang to 6-week-old female ICR mice for 4, 8, or 12 days. The female mice were injected PMSG and hCG for ovarian hyperstimulation. And then recovered ovaries were minced and extracted mRNA and analyzed cell viability related gene expression. We chose the caspase-3 for cell apoptosis, MAPK and MPG genes for cell viability and DNA repair. To compare the differences, we set a control group treated with plain water at the same volume by the same way. Results : In case of administration of Palmultang, the mean number of total ovulated oocytes and the number of morphologically normal oocytes increased significantly compared to a control group. We were also examined the embryonic developmental competence in vitro. The administration of Palmultang in a concentration with 10 and 100 mg/ml were beneficial effect of embryonic development in preimplantation period. The administration of Palmultang play a role of prevention of cell apoptosis and DNA damages and also increased cell proliferation resulted in ovarian functions. Conclusion : From our results suggested that the medication of Palmultang has beneficial effect on reproductive functions of female mice via prevention of cell apoptosis and DNA damaging and promotion of cell proliferation.