• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.37.1-37.1
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• 2021

Observations suggest the star formation in nuclear rings of barred galaxies proceeds episodically in time and sometimes asymmetrically in space. Existing theories and numerical simulations suggest that the episodic star formation is perhaps due to either supernova feedback combined with fluid instabilities or time-varying mass inflow rate. However, it has been challenging to discern what dominates in shaping the star formation history because the effects of the inflow and feedback are blended in global simulations of nuclear rings. To understand their effects separately, we construct semi-global models of nuclear rings, which treat the mass inflow rate as a model parameter. By running simulations with the inflow rates kept constant or oscillating in time, we find that the star formation rate (SFR) of the rings varies coherently with the inflow rate, while the feedback is responsible only for stochastic fluctuations of the SFR within a factor of two. The feedback instead plays an important role in maintaining the vertical dynamical equilibrium and setting the depletion time. While the asymmetry in the inflow does not necessarily lead to the asymmetry in the star formation, we find that the rings undergo a transient period of lopsided star formation when the inflow rate of only one dust lane is suddenly increased.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.2
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• pp.100-106
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• 1998

The wide open throttle performance and piston temperatures were measured by the change of fuel : gasoline and liquefied petroleum gas(LPG). Bench test method was developed and experimented to study the effect of temperature on the formation of carbon deposit. The bench test results were confirmed by measuring the piston temperature and observing the deposit production rate at an actual engine running condition. Results show that if the fuel of spark ignition engine is changed from gasoline to LPG, the output power decreases about 10% and the piston temperatures increase about 40~55$^{\circ}C$. In actual engine tests, because of this temperature increase, it was observed that the quantity of carbon deposit in the top ring groove increased in a big degree. Consuquently, it is known that the fing sticking may occur if the gasoline engine was rebuilt to LPG fuelled engine. Therefore, in order to preserve the durability of LPG fuelled engine, it is necessary to lower the piston temperature by hardware modificationor to reduce the carbon deposit by the improvement of engine oil.

• Journal of Korean Dental Science
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• v.8 no.2
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• pp.74-81
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• 2015

Purpose: In osteoclast differentiation, actin-rich membrane protrusions play a crucial role in cell adhesion. Odontogenic ameloblast-associated protein (Odam) contributes to cell adhesion by inducing actin rearrangement. Odam-mediated RhoA activity may play a significant role in multinucleation of osteoclasts. However, the precise function of Odam in osteoclast cell adhesion and differentiation remains largely unknown. Here, we identify a critical role for Odam in inducing osteoclast adhesion and differentiation. Materials and Methods: The expression of Odam in osteoclasts was evaluated by immunohistochemistry. Primary mouse bone marrow and RAW264.7 cells were used to test the cell adhesion and actin ring formation induced by Odam. Result: Odam was expressed in osteoclasts around alveolar bone. Odam transfection induced actin filament rearrangement and cell adhesion compared with the control or collagen groups. Overexpression of Odam promoted actin stress fiber remodeling and cell adhesion, resulting in increased osteoclast fusion. Conclusion: These results suggest that Odam expression in primary mouse osteoclasts and RAW264.7 cells promotes their adhesion, resulting in the induction of osteoclast differentiation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.7
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• pp.918-927
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• 1999

In the fully developed internal flow fields, there are complex transition flows caused by interaction of the cross flow and jet when jet is Injected Into the flow. These interactions are studied by means of the flow visualization methods. An instantaneous laser tomographic method is used to reveal the physical mechanism and the structure of vortices formation in the branch pipe flow. The velocity range of cross flow of the pipe is 0.7m/s and the corresponding Reynolds number $R_{cf}$, based on the duct height is $5.6{\times}10^3$, diameter/height ratios(d/H) 0.14 and velocity ratios 3.0. Oil mist with the size of $10{\mu}m$ diameter is used for the scattering particle. The instantaneous topological features of the vortex ring roll-up of the jet shear layer and characteristics of this flow are studied in detail by performing flow visualization in rectangular duct flow. It is found that the formation and roll-up of ring vortices is a periodic phenomenon. The detailed topology of the vortices in the near field of a cross -flow jet and the mechanism associated with them give enforced hints of vortex breakdown within the vortex system due to the interaction of the jet and the cross-flow.

• The Journal of Korean Obstetrics and Gynecology
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• v.24 no.4
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• pp.1-9
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• 2011

Purpose: Wogonin is an active component isolated from scutellariae radix. This study was conducted to evaluate the inhibitory effect of wogonin mixed with hydrogel on osteoclast differentiation. Methods: It was performed to estimate cytotoxicity of Wogonin alginate hydrogel disk(WHD) in BMMs stimulated with RANKL, M-CSF. ROS synthesis and actin ring formation were analysed to observe the effect of WHD. Results: WHD has no cytotoxicity at the concentration of 0.1 ${\mu}g/ml$ or lower. 0.1 ${\mu}g/ml$, 1 ${\mu}g/ml$ WHD restrained the synthesis of ROS and 0.1 ${\mu}g/ml$, 1 ${\mu}g/ml$ WHD restrained the formation of actin ring. Conclusions: WHD has the inhibitory effect of osteoclast differentiation and bone resorption. Further studies are needed to treat osteoporosis by herbal medicine.

• Bulletin of the Korean Chemical Society
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• v.26 no.4
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• pp.641-644
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• 2005

Nucleophilic addition reactions of benzylamines $(XC_6H_4CH_2NH_2)\;to\;{\beta}$-cyanostilbenes ($YC_6H_4CH=C(CN)C_6H_4$Y’) have been studied in acetonitrile at 30.0 oC. A greater degree of N-$C_{\alpha}$ bond formation (larger ${\beta}_X$) is obtained with a stronger electron-withdrawing substituent in either ${\alpha}-\;(\delta\sigma_Y\;{\gt}\;0)\;or\;{\beta}-ring\;(\delta\sigma_{Y'}\;{\gt}$ 0). A stronger charge development is observed in the TS on $C_{\beta}\;(\rho_{Y'}$= 1.06 for X=Y=H) rather than on $C_{\alpha}\;(\rho_{Y}$ = 0.62 for X=Y’H) indicating the lag in the resonance development into the activating group (CN) on $C_{\beta}$ in the transition state. Similarly, the magnitude of $\rho$$_{XY'}$(−0.72) is greater than $\rho_{XY}$ (−0.66) due to a stronger interaction of the nucleophile with $\beta$-ring than $\alpha$-ring. The positive sign of $\rho_{YY'}$correctly reflects $\pi$ bond cleavage between the two rings in the TS. Relatively large kinetic isotope effects ($k_H/k_D\;{\geq}$ 2.0) involving deuterated nucleophiles ($XC_6H_4CH_2ND_2$) suggest a four-membered cyclic TS in which concurrent N-C$_{\alpha}$ and H(D)-C$_{\beta}$ bond formation occurs.

• The Journal of the Petrological Society of Korea
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• v.6 no.2
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• pp.96-110
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• 1997

The Wondong Caldera, formed by the voluminous eruption of the rhyolitic ashflows of the Wondong Tuff which is about 1,550 m thick at the intracaldera and 550 m at the outflow, is a resurgent caldera which shows a dome structure on the central exposure of the caldera. The Wondong caldera volcanism eviscerated the magma chamber by a series of explosive eruptions during which rhyolitic magma was ejected, as small fallouts and voluminous ash-flows, to form the Wondong Tuff. The explosive eruptions began with ash-falls, progressed through pumice-falls and transmitted ash-flows. During the ash-flow phase the initial central vent eruption transmitted into late ring-fissure eruption which accompanied with caldera collapse. Contemporaneous collapse of the roop of the chamber resulted in the formation of the Wondong Caldera, a subcircular depression subsiding about 1,930 deep. Following the collapse, quartz porphyry was intruded as ring dykes along the ring fracture near the southwestern caldera rim. Subsequently the central part of the caldera floor began to be uplifted into a circular resurgent dome by the rising of residual magma. Concurrent with the resurgent doming, the volcaniclastic sediments of Hwajeri Formation were accumulated in the caldera moat and then rhyodacite lava erupted from the initial central resurgent dome and another ash-flow tuff from the northern ring fracture. After the sedimentation, the find-grained granodiorite was intruded as an arc along the eastern ring fracture of the caldera. Finally in the central part, the resurgent magma was emplaced as a hornblende biotite granite stock that formed the central dome.

• Textile Coloration and Finishing
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• v.13 no.5
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• pp.58-58
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• 2001

This study surveys the fiber behavior in yarn formation and the physical properties of Solo-spun yarn. The specimens were made by six types of Solo-spun rollers with fixed twist multiplier. The physical properties such as yarn count, evenness, strength, and breaking elongation of these yarns were compared with the properties of ring spun yarns and analysed with the mechanism of Solo-spun yarn formation. The grooves on the surface of Solo-spun roller divide the web and interfere the twist propagation. These phenomena cause the uneven draft and the fly of fiber, so the Solo-spun yarn becomes finer than fing-spun yarn and the yarn breaking strength and elongation deteriorate, but these demerits can be improved with rounding the protruded edge of Solo-spun roller grooves.

• Textile Coloration and Finishing
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• v.13 no.5
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• pp.346-352
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• 2001

This study surveys the fiber behavior in yam formation and the physical properties of Solo-spun yam. The specimens were made by six types of Solo-spun rollers with fixed twist multiplier. The physical properties such as yam count, evenness, strength, and breaking elongation of these yams were compared with the properties of ring spun yams and analysed with the mechanism of Solo-spun yarn formation. The grooves on the surface of Solo-spun roller divide the web and interfere the twist propagation. These phenomena cause the uneven draft and the fly of fiber, so the Solo-spun yam becomes finer than fing-spun yam and the yam breaking strength and elongation deteriorate, but these demerits can be improved with rounding the protruded edge of Solo-spun roller grooves.

• YAKHAK HOEJI
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• v.54 no.6
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• pp.461-465
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• 2010

We investigated the role of L-type $Ca^{2+}$ channel in receptor activator of nuclear factor-kappaB ligand (RANKL)-induced osteoclast formation. BayK 8644, a L-type $Ca^{2+}$ channel agonist, was shown to increase the RANKLinduced osteoclastogenesis and actin ring formation in mouse bone marrow-dereived macrophage (BMM) culture system. BayK 8644 stimulated RANKL-induced extracellular signal-regulated kinase (ERK) and p38 MAP kinase (MAPK) activation, which leads to increased nuclear factor of activated T cells (NFAT)c1 expression. Taken together, these data indicate that L-type $Ca^{2+}$ channel regulates osteoclast formation possibly through ERK- and p38-mediated NFATc1 expression.