• International Journal of Naval Architecture and Ocean Engineering
• /
• v.4 no.4
• /
• pp.477-487
• /
• 2012

We investigated the aerodynamic characteristics of a three-dimensional (3D) wing with an endplate in the vicinity of the free surface by solving incompressible Navier-Stokes equations with the turbulence closure model. The endplate causes a blockage effect on the flow, and an additional viscous effect especially near the endplate. These combined effects of the endplate significantly reduce the magnitudes of the velocities under the lower surface of the wing, thereby enhancing aerodynamic performance in terms of the force coefficients. The maximum lift-to-drag ratio of a wing with an endplate is increased 46% compared to that of wing without an endplate at the lowest clearance. The tip vortex of a wing-with-endplate (WWE) moved laterally to a greater extent than that of a wing-without-endplate (WOE). This causes a decrease in the induced drag, resulting in a reduction in the total drag.

• International Journal of Fluid Machinery and Systems
• /
• v.3 no.1
• /
• pp.50-57
• /
• 2010

The attachment of inducer in front of main impeller is a powerful method to improve cavitation performance. Cavitation surge oscillation, however, often occurs at partial flow rate and extremely low suction pressure. As the cavitation surge oscillation with low frequency of about 10 Hz occurs in a close relation between the inlet backflow cavitation and the growth of blade cavity into the throat section of blade passage, one method of installing an axi-asymmetrical plate upstream of inducer has been proposed to suppress the oscillation. The inlet flow distortion due to the axi-asymmetrical plate makes different elongations of cavities on all blades, which prevent the flow from becoming simultaneously unstable at all throat sections. In the present study, changes of the suppression effects with the axial distance between the inducer inlet and the plate and the changes with the blockage ratios of plate area to the cross-sectional area of inducer inlet are investigated for helical inducers with tip blade angles of $8^{\circ}$ and $14^{\circ}$. Then a conceivable application will be proposed to suppress the cavitation surge oscillation by installing axi-asymmetrical inlet plate.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.16 no.6
• /
• pp.811-818
• /
• 2013

In this paper, we have designed the elliptical dual offset gregorian antenna which can use Ka band earth station antennas in the fixed-satellite service. The structure of antenna is increasing the antenna gain by decreasing blockage areas and decreasing wind effects by shortening height of the antenna. The corrugate horn antenna for this antenna has symmetric radiation patterns and low side lobe levels that can meet ITU-R envelope. The distribution of electric field on a aperture of main reflector is calculated by an ray-tracing method that use the radiation pattern of the feed horn. The final geometric of antena is decided by choosing the distribution that comply with antenna requirement. The FEKO analysed electrical performance of this antenna. The fabricated antenna has 45.0dBi(@30.0GHz)/41.7dBi(@20.2GHz), high efficiency and low side lobe level that meet ITU-R S. 580-6 envelope.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2016.05a
• /
• pp.164-164
• /
• 2016

Radar rainfall estimates have been widely used in calculating rainfall amount approximately and predicting flood risks. The radar rainfall estimates have a number of error sources such as beam blockage and ground clutter hinder their applications to hydrological flood forecasting. Moreover, it has been reported in paper that those errors are inter-correlated spatially and temporally. Therefore, in the current study, we tested influence about spatio-temporal errors in radar rainfall estimates. Spatio-temporal errors were simulated through a stochastic simulation model, called Multivariate Autoregressive (MAR). For runoff simulation, the Nam River basin in South Korea was used with the distributed rainfall-runoff model, Vflo. The results indicated that spatio-temporal dependent errors caused much higher variations in peak discharge than spatial dependent errors. To further investigate the effect of the magnitude of time correlation among radar errors, different magnitudes of temporal correlations were employed during the rainfall-runoff simulation. The results indicated that strong correlation caused a higher variation in peak discharge. This concluded that the effects on reducing temporal and spatial correlation must be taken in addition to correcting the biases in radar rainfall estimates. Acknowledgements This research was supported by a grant from a Strategic Research Project (Development of Flood Warning and Snowfall Estimation Platform Using Hydrological Radars), which was funded by the Korea Institute of Construction Technology.

• Journal of the Society of Naval Architects of Korea
• /
• v.53 no.6
• /
• pp.465-472
• /
• 2016

A study was carried out to investigate typical features of natural supercavitation generated behind axisymmetric bodies such as disk and cone shaped cavitators. Main focuses of the study were to observe formation process of the supercavity and to measure drag forces acting on cavitators. Experiments were carried out at the cavitation tunnel of the Chungnam National University (CNU-CT), which has a capability to make sufficient flow speed for supercavitation experiments and to remove broken cavity bubbles coming back to the test section. Blockage effects on supercavity dimensions were evaluated and an effort was made to correlate tunnel experiments with unbounded flow. On the basis of experimental and numerical results, geometrical features of supercavities and characteristics of drag forces were examined and their relations were proposed.

• Korean Journal of Clinical Pharmacy
• /
• v.29 no.2
• /
• pp.133-137
• /
• 2019

Atorvastatin is one of the most widely prescribed medications for dyslipidemia treatment. In Korea, post combined therapy with ezetimibe, a 73-year-old woman was reported by a community pharmacy to have experienced visual field defect, which recovered after drug discontinuation. She had never experienced this symptom before, and several studies have reported an association between use of statins and visual disorders such as blurred vision, diplopia, and cataract. Blockage of cholesterol accumulation, oxidative stress, or myopathy is expected to be a cause of this symptom. Naranjo scale, Korean causality assessment algorithm (Ver.2), and World Health Organization-Uppsala Monitoring Center (WHO-UMC) criteria were the three tools used to determine causality between the visual disorder and atorvastatin. The results represent 'probable', 'certain', and 'probable/likely' causality, respectively. Our results, in combination with a review of literature, indicate that ocular adverse effects are highly likely related to atorvastatin.

• Journal of Korean Clinical Nursing Research
• /
• v.27 no.1
• /
• pp.85-97
• /
• 2021

Purpose: The purpose of this study was to develop a video education program (VEP) for the caregivers and to verify its effectiveness on the maintenance of a peripheral intravenous catheter (PIVC) among hospitalized children. Methods: The VEP was developed through a literature review, educational need assessment of caregivers, and interviews with pediatric nurses, and validation of an expert group. The effectiveness of the VEP was tested on 102 caregivers and their children in a children's hospital at D city. A nonequivalent control group pretest-posttest design was used in which different types of intervention were given to caregivers in intervention group (n=51) and control group (n=51). All caregivers received brief verbal information about the PIVC maintenance. The intervention group was additionally provided with VEP using a smartphone. Data were analyzed using SPSS/Win 21.0 program. Results: The caregivers' knowledge score on PIVC maintenance in the intervention group was significantly higher than that of the control group. The numbers of flushing in case of blockage of PIVC and gauze dressing change of the intervention group was significantly lower than those of the control group. Conclusion: These results suggest that the VEP developed in this study can be useful for the maintenance of PIVC among hospitalized children.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.7
• /
• pp.54-65
• /
• 2020

This randomized pre-post-controlled experimental study determined the effect on patients' anxiety, stress, systolic blood pressure, heart rate and Bis index when the Healing Beats program is applied after epidural blockage. The subjects were selected from the patients who visited the Department of Anesthesiology and Pain for the treatment of epidural blockage and volunteered through the recruitment announcement. A total of 74 sets of data were collected and analyzed with 25 subjects in the experimental group, 24 in the placebo group, and 25 in the control group. The data was analyzed using descriptive statistics, x2-tests, F-tests and repeated measures of ANOVA. As a result of the study, the general characteristics and variables of the experimental group, placebo group, and control group were all the same, and anxiety was measured twice before and after the study. There were significant differences between groups (F=27.175, p<.001), and stress (F=4.78, p<.001), heart rate (F=4.22, p<.001) and the Bis index (F=7.96, p<.001) were analyzed by variance according to population and time. There was a significant difference. However, there was no significant difference in systolic blood pressure (F=1.23, p=.298). In conclusion, the Healing Beats program can be used as an effective and effective intervention for sedation in clinical situations or stressful situations.

• Biomedical Science Letters
• /
• v.16 no.4
• /
• pp.229-238
• /
• 2010

Chicken Mx protein (cMx) induced interferon (IFN) is an antiviral protein to inhibit replication of RNA virus, particularly negative stranded RNA virus, through blockage of transfortation of viral RNA and proteins. In order to determine antiviral effects of cMx from different MHC haplotype chicken, we characterized cMx gene by studying on nucleotide sequencing, antiviral effects to Newcastle disease virus, VSV and MDV, and transcription activities. Three types of eMx genes (2,118 bp) were detected from the different MHC haplotype chickens [B19 (N), B15(F) and B21 (GSP)] chickens, which have showed different susceptible to Marek's disease (MD). Several amino acid substitutions were showed in the cMx. The amino acid 548 and 631 in the cMxs from N and F, chickens susceptible to MD, was Val and Asn which was important on antiviral effects, and showed in resistant cMx. Those in the cMx from GSP, chicken resistant to MD, were same that showed in susceptible cMx. Though every cMx transactivated the expression of the reporter gene, the transcription activation by resistant cMx from N and F was lower compared to that by susceptible cMx from GSP. The decease of the cell growth in the resistant cMx cloned cells was seen in comparison with another cMx clone cells. Replication of NDV and VSV was suppressed in the clones with resistant cMx from N and F. NMx258-transducted cells lack of antiviral effects, and NMx437 or NMx646-transducted cells was showed 60% of antiviral effects compared to NMx705. Mean death time (MDT) and hemaggutination (HA) titer to NDV was long and low in the eggs of N and F lines, but short and high in the egg of GSP line. Interestingly, strong suppression to NDV was observed in the clone with N-Mx and in the eggs of N line. However, the effects of Mx for replication of vvMDV1 have not been. Thus, resistant types of cMx, N- and F-Mx, have showed the anti-viral effects to only RNA virus including NDV and VSV, but not to DNA virus. Antiviral effects of cMx were required whole length of amino acid including Val and Asn in amino acid 548 and 631.

• BMB Reports
• /
• v.45 no.9
• /
• pp.489-495
• /
• 2012

Ischemia is a blockage of blood supply due to an embolism or a hemorrhage in a blood vessel. When an organ cannot receive oxygenated blood and can therefore no longer replenish its blood supply due to ischemia, stresses, such as the disruption of blood glucose homeostasis, hypoglycemia and hypoxia, activate the AMPK complex. LKB1 and $CaMKK{\beta}$ are essential activators of the AMPK signaling pathway. AMPK triggers proangiogenic effects through the eNOS protein in tissues with ischemic conditions, where cells are vulnerable to apoptosis, autophagy and necrosis. The AMPK complex acts to restore blood glucose levels and ATP levels back to homeostasis. This review will discuss AMPK, as well as its key activators (LKB1 and $CaMKK{\beta}$), as a central energy regulator and evaluate the upstream and downstream regulating pathways of AMPK. We will also discuss how we can control this important enzyme in ischemic conditions to prevent harmful effects in patients with vascular damage.