• Journal of the Society of Naval Architects of Korea
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• v.55 no.4
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• pp.330-340
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• 2018

In the present works, the High-speed Cavitation Tunnel (HCT) has been designed and manufactured to have the large test section to conduct various supercavitation experiments. The large amount of air ventilated behind a cavitator produces lots of tiny bubbles, which prevent clear observation of supercavitation at the test section. To collect small bubbles effectively, a bubble collecting section of large volume is equipped upstream of the test section. HCT has the test section dimension of $0.3^H{\times}0.3^W{\times}3.0^L\;m^3$ and provides maximum flow speed of 20.4 m/s at the test section. The blockage and Froude effects on the ventilated supercavitation are investigated successfully at the test section. The basic studies such as the supercavitation evolution, drag measurements and cavity shape extraction with air flow rate are also carried out in HCT.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.947-952
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• 2015

To supplement energy needs and take advantage of renewable energy sources, many wind farms are currently being built in mountainous areas under the supervision of the Korean government. However, operation of these wind farms can cause serious threats to national security due to Doppler modulation from the wind turbines causing interference with military radar operating in the vicinity. Therefore it is necessary to develop methods to analyze the Doppler frequency during the operation of wind turbines and the effect on radar signals. Based on modeling of the mountainous region, blockage analysis, turbine motion and the radar signals, this paper proposes a signal processing method to extract and analyze the Doppler frequency. Simulation results showed the change of Doppler frequency over time caused by the geometry of the mountainous area and the wind turbine.

• Journal of the Korean Geotechnical Society
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• v.38 no.11
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• pp.7-17
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• 2022

This study investigates the effect of cylindrical baffle arrays behind a rigid barrier on debris flow behavior and dynamic impact load. Small-scale tests were performed with various transverse blockage ratios and row numbers of baffles. High-speed cameras were installed at the flume's top and side, and load cells were installed in front of the rigid barrier. Moreover, glass beads simulated large boulders with debris flow in the flume. Test results revealed that the impact load of debris flow on the rigid barrier was significantly reduced using the cylindrical baffles behind the rigid barrier. In addition, the increased transverse blockage ratio of baffle arrays led to a greater impact load of debris flow because of flow suppression due to the baffle arrays.

• ETRI Journal
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• v.35 no.5
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• pp.775-785
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• 2013

Because of their exclusive features, millimeter wave directive mesh networks can be considered for small cell backhaul support in urban environments. For this purpose, a network of closely spaced stations has been considered with very directive line-of-sight links operating in the 60-GHz band. An attempt is made to evaluate channel response and interference behavior in such a network, taking into account the effect of building blockage. A simple grid of building blocks is considered as the propagation environment, and wave propagation is simulated using 2.5-dimensional (2.5D) ray tracing (2D with ground effect) to calculate the received signal at different nodes in the network. The results are compared with free space predictions and used to evaluate interference at all nodes in the channel and describe certain characteristics of links, such as the delay profile and the correlation length.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.111-115
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• 2002

The objective of this work is to develop improved slip factor model and correction method to predict flow through impeller in forward-curved centrifugal fan by investigating the validity of various slip factor models. Both steady and unsteady three-dimensional CFD analyses were performed with a commercial code tn validate the slip factor model and the correction method. The results show that the improved slip factor model presented in this paper could provide more accurate predictions for forward-curved centrifugal impeller than the other slip factor models since the presented model takes into account the effect of blade curvature. The comparison with CFD results also shows that the improved slip factor model coupled with the present correction method provides accurate predictions for mass-averaged absolute circumferential velocity at the exit of impeller near and above the flow rate of peaktotal pressure coefficient.

• Archives of Pharmacal Research
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• v.25 no.4
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• pp.500-504
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• 2002

Propolis, obtained from honeybee hives, has been used in Oriental folk medicine as an anti-inflammatory, anti-carcinogenic, and immunomodulatory agent. There is considerable evidence suggesting that angiogenesis and chronic inflammation are codependent. Blockage of angiogenesis results in an anti-inflammatory effect. Ethanol (EEP) and ether extracts of propolis (REP), and caffeic acid phenethyl ester (CAPE), an active component of propolis, were examined for their anti-angiogenic activities using the chick embryo chorioallantoic membrane (CAM), and the calf pulmonary arterial endothelial (CPAE) cell proliferation, assays. The presence of EEP, REP and CAPE inhibited angiogenesis in the CAM assay and the proliferation of CPAE cells. The results suggest that anti-angiogenic activities of EEP, REP and CAPE are also responsible for their anti-inflammatory effect.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.132-137
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• 2006

Supercooled type ice slurry system is hard to keep a proper supercooling degree when solution becomes supercooling state. This is the reason of the ice blockage in pipe or cooling part due to an unstable cooling state. In this study, a cooling experiment was performed to pressurized solution in a stationary state. The behaviors during the supercooled aqueous solution were investigated at fixed flow rate of brine and aqueous solution of ethylene glycol 7 mass%. Also the effect to the freezing point of supercooled aqueous solution was investigated to the different pressure 101, 202, 303, and 404 kPa. At results, the pressure of the aqueous solution in the cylinder increased the supercooling degree increased and dissolution of supercooled point decreased.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2020.10a
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• pp.219-219
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• 2020

Kaempferol (3,4',5,7-tetrahydroxyflavone), a flavonoid found in beans, broccoli, garlic, etc., has been used in natural medicine as an anti-inflammatory and antioxidant. This experiment was carried out to evaluate the anti-apoptotic effect of kaempferol in 12-O-tetradecanoylphorbol 13-acetate (TPA)-treated Normal Human Dermal Fibroblast (NHDF). Kaempferol inhibited the production of intracellular Reactive Oxygen Species (ROS) induced by TPA in NHDF. Kaempferol significantly blocks the phosphorylation of extracellular signal-regulated kinase responsible for the activation of nuclear factor-kappa B. In addition, kaempferol significantly attenuated the expression of Bax and cleaved caspase-3 as regulated by the phosphorylation of nuclear factor-kappa B during its blockage of TPA-induced apoptotic cell death. These findings suggest that kaempferol protects the apoptotic signaling pathway induced by TPA through modulating intracellular ROS in NHDF.

• The Korean Journal of Pain
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• v.21 no.3
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• pp.202-205
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• 2008

Background: Lumbar radicular pain is a frequent and often debilitating event. Although many treatment methods have been described in several studies, the available evidences regarding efficacy is not sufficient enough to draw definitive conclusions on an optimal therapy regime. Pulsed radiofrequency (RF) treatment was found to exert a beneficial effect on intractable radicular pain in individuals. The purpose of this study was to assess the efficacy of pulsed RF of the dorsal root ganglion for chronic lumbar radicular pain. Methods: Twenty five patients with chronic lumbar radicular pain that was refractory to selective nerve root blockage met the inclusion criteria of our study and received pulsed RF treatment. The average numeric rating scale (NRS) for leg pain during usual activities and the Oswestry disability index (ODI) were measured at 1 and 3 months after the procedure. Results: Of the 25 patients accepted for pulsed RF treatment, one dropped out due to a vertebral compression fracture during this study. ODI and NRS showed a positive trend in favor of the pulsed RF treatment. No significant complications were observed during the study period. Conclusions: It appears that pulsed RF treatment of the lumbar spinal dorsal root ganglion may be an effective treatment method for patients suffering from lumbar radicular pain, and who were not responsive to selective nerve root blockage.

• The Journal of Internal Korean Medicine
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• v.29 no.1
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• pp.243-257
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• 2008

Myostatin, a negative regulator of myogenesis, is shown to function by controlling the proliferation of myoblasts. In this study we show that myostatin is an inhibitor of myoblast differentiation and that this inhibition is mediated through Smad 3. To determine MyoD expression by Dodamtang treatment, we compared the expression pattern of $C_{2}C_{12}$ mouse myoblasts that constitutively express myostatin with control cells. In vitro, increasing concentrations of Dodamtang reversibly prevented the myogenic blockage of myoblasts by myostatin expression. ELISA assay, Western and confocal analysis indicated that treatment of Dodamtang to the low serum culture media increased the levels of MyoD leading to the inhibition of myogenic differentiation by myostatin. The stable transfection of $C_{2}C_{12}$ myoblasts with myostatin expressing constructs did rescue MyoD-induced myogenic differentiation. Consistent with this, the treatment of Dodamtang rescued the expression of a MyoD in $C_{2}C_{12}$ myoblasts treated with myostatin. Taken together, these results suggest that induction of MyoD by Dodamtang inhibits myostatin activity and expression via SMAD3 resulting in the rescue of the myoblasts to differentiate into myotubes. Thus we propose that myostatin action by Dodamtang plays a critical role in myogenic differentiation and that the muscular hyperplasia and hypertrophy seen in animals that blockage of functional myostatin is because of deregulated proliferation and differentiation of myoblasts.