• Journal of Korean Society of Steel Construction
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• v.22 no.1
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• pp.1-12
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• 2010

According to the capacity design concept which forms the basis of the current steel seismic codes, the braces in concentrically braced frames (CBFs) should dissipate seismic energy through cyclic tension yielding and cyclic compression buckling while the beams and the columns should remain elastic. Brace buckling in inverted V-braced frames induces unbalanced vertical forces which, in turn, impose the additional beam moments and column axial forces. However, due to difficulty in predicting the location of buckling stories, the most conservative approach implied in the design code is to estimate the column axial forces by adding all the unbalanced vertical forces in the upper stories. One alternative approach, less conservative and recommended by the current code, is to estimate the column axial forces based on the amplified seismic load expected at the mechanism-level response. Both are either too conservative or lacking technical foundation. In this paper, three combination rules for a rational estimation of the column axial forces were proposed. The idea central to the three methods is to detect the stories of high buckling potential based on pushover analysis and dynamic behavior. The unbalanced vertical forces in the stories detected as high buckling potential are summed in a linear manner while those in other stories are combined by following the SRSS(square root of sum of squares) rule. The accuracy and design advantage of the three methods were validated by comparing extensive inelastic dynamic analysis results. The mode-shape based method(MSBM), which is both simple and accurate, is recommended as the method of choice for practicing engineers among the three.

• Journal of Periodontal and Implant Science
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• v.25 no.1
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• pp.133-145
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• 1995

The migration and proliferation of periodontal ligament cells are desired goal of periodontal regeneration therapy. PDGF and $TGF-{\beta}1$ are well known to regulate the cell activity of mesenchymal origin cell. The purpose of this study was to determine the effects of these growth factors on human gingival fibroblast and periodontal ligament cell actvity, and to identify the regulatory effect of $TGF-{\beta}1$ on the response to PDGF by MIT assay. Human gingival fibroblast and periodontal ligament cells were cultured from extracted teeth for non-periodontal reason. Cultured human gingival fibroblast and periodontal ligament cells in vitro were treated with polyperpetide growth factor PDGF and $TGF-{\beta}1$ in both a dose and time - dependent manner. Cell morphology were determined by inverted microscope and cell acitivity were determined by MIT assay. The result of this study demonstrated that PDGF and $TGF-{\beta}1$ were not changed the morphology of these cell compared with control group. PDGF or $TGF-{\beta}1$ increased cell activity of periodontal ligament cell in dose and time dependent manner but gingival fibroblast were decreased to the level of control group at third day. Additionally, incubation with $TGF-{\beta}1$ addition to PDGF resulted in a enhanced cell activity of PDGF. Therefore, cell acitivty of gingival fibroblast were not changed compared with control group. This stiudy demonstrates that PDGF and $TGF-{\beta}1$ are major mitogens for human periodontal ligament cell in vitro, and $TGF-{\beta}1$ is a regulator of cell activity to PDGF in human gingival fibroblast and periodontal ligament cell.

• The Korean Journal of Pharmacology
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• v.25 no.1
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• pp.23-30
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• 1989

Buprenorphine, one of the mixed agonist-antagonist opioid drugs was used to inverstigate the opioid receptor on frog sciatic nerve A fibers. Action potentials were recorded for 4 hrs by a sucrose gap apparatus which were separated by four rubber membranes. To examine the one of the mechanism of action of buprenorphine, meperidine or naloxone was added after or before the treatment of buprenorphine. The results of this experiment were as follows: 1. Buprenorphine suppressed significantly the compound action potentials of frog sciatic nerve, and the maximal effects were shown both at $10^{-4}\;M$ and at $10^{-8}\;M$. 2. The dose-response relationship of buprenorphine on the depressant effect in frog sciatic nerve was biphasic and inverted U-shaped. 3. Buprenorphine blocked the effect of Meperidine $(10^{-3}\;M)$ on this preparation. 4. The depressant effcct of Buprenorphine on frog sciatic nerve was blocked by $10^{-8}\;M$ naloxone. From the above results, buprenorphine acts as one of agoinist-antagonistic effect on frog sciatic nerve, and the opioid receptor on this preparation is located on or near the intracellular opening of the sodium channels, which are sensitive to naloxone.

• The Korea Journal of Herbology
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• v.20 no.4
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• pp.27-31
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• 2005

Objectives : The anticancer response of three different types of water extracts of Zingiberaceae Curcuma longa L. tested for sarcoma 180. Only few studies carried out to investigate the effects of other contents of Curcuma longa L. in anticancer activities, therefore, in this study we have investigated the effects of other component then curcumin in Curcuma longa L. for anticancer a activities. Methods : Three different types of water extracts of Curcuma longa L. were prepared as follows. The sarcoma cells (S180) were maintained in Dulbecco's modified Eagle's medium (DMEM) and were seeded on 24-well cell culture cluster flat bottom with lid tissue culture treated non-pyrogenic polystyrene. The growth of sarcoma 180 was monitored for 1, 2 and 5 days. The sarcoma cells were pictured using inverted microscope and cell density was counted using hemocytometry. Results : After 5 days in the culture medium the results showed high growth of sarcoma 180 for control condition and the surface of CCP plates were fully covered with the cells. In case of medium in which the 10% of filtered water extract of Curcuma longa L. was added a very limited growth of sarcoma 180 was observed. The results were showed only small difference in cell density for two different concentrations of unfiltered water extracts of Curcuma longa L. whereasin case of filtered water extracts the control of sarcoma growth shows better result. Conclusion : The filtered water extracts showed the best result relatively to the unfiltered water extracts for two different concentrations. This indicates that the water extracts of Curcuma longa L. can have anticancer activities possibly without curcumin.

• Journal of Korean Neurosurgical Society
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• v.57 no.1
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• pp.1-5
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• 2015

Objective : Cerebral vessels, such as intracerebral perforating arterioles isolated from rat brain, have been widely used as an ex vivo model to study the cerebrovascular function associated with cerebrovascular disorders and the therapeutic effects of various pharmacological agents. These perforating arterioles, however, have demonstrated differences in the vascular architecture and reactivity compared with a larger leptomeningeal artery which has been commonly implicated in cerebrovascular disease. In this study, therefore, we developed the method for studying cerebrovascular function utilizing the olfactory artery isolated from the mouse brain. Methods : The olfactory artery (OA) was isolated from the C57/BL6 wild-type mouse brain. After removing connective tissues, one side of the isolated vessel segment (approximately $-500{\mu}m$ in length) was cannulated and the opposite end of the vessel was completely sealed while being viewed with an inverted microscope. After verifying the absence of pressure leakage, we examined the vascular reactivity to various vasoactive agents under the fixed intravascular pressure (60 mm Hg). Results : We found that the isolated mouse OAs were able to constrict in response to vasoconstrictors, including KCl, phenylephrine, endothelin-1, and prostaglandin $PGH_2$. Moreover, this isolated vessel demonstrated vasodilation in a dose-dependent manner when vasodilatory agents, acetylcholine and bradykinin, were applied. Conclusion : Our findings suggest that the isolated olfactory artery would provide as a useful ex vivo model to study the molecular and cellular mechanisms of vascular function underlying cerebrovascular disorders and the direct effects of such disease-modifying pathways on cerebrovascular function utilizing pharmacological agents and genetically modified mouse models.

• Korean Journal of Optics and Photonics
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• v.17 no.1
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• pp.54-59
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• 2006

Biophotonic sensors based on polymer waveguide with Bragg reflection grating are demonstrated in this work. Waveguide Bragg reflectors were designed by using the effective index method and the transmission matrix method. The grating pattern was formed by exposing the laser interference pattern on a photoresist. On top of the inverted rib waveguide, the Bragg reflection grating was inscribed by the O2 plasma etching. In order to perform the bio-molecule detection experiment, a calixarene molecule was self-assembled on top of thin Au film deposited on the waveguide Bragg reflector. To measure the response of the sensor, several PBS solutions with different concentrations of potassium ion from 1 pM to $100\;{\mu}M$ were dropped on the sensor surface. The shift of Bragg reflection wavelength was observed from the fabricated sensor device, which was proportional to the concentration of potassium ion ranging from 1 pM to 108 pM.

• Restorative Dentistry and Endodontics
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• v.25 no.4
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• pp.606-618
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• 2000

Dental pulp infection is most commonly caused by extensive dental caries, and some bacterial species invade root canals; bacterial components and products are thought to be associated with the pathogenesis of periapical periodontitis. A principle driving force behind pulpal disease response appears to lie in the host immune system's to bacteria and their products. We examined the production of interleukin $1{\beta}$ (IL-$1{\beta}$) and tumor necrosis factor ${\alpha}$(TNF-${\alpha}$) from human peripheral mononuclear cells, lymphocytes and monocytes stimulated by heat-killed Acitnobacillus actinomycetemcomitans (ATCC 29523), Porphyromonas gingivalis (ATCC 33277) and Prevotella intermedia (ATCC 25611), and also by their sonicated bacterial extracts (SBE), respectively. The effects of three strains of heat-killed bacteria and their SBEs on the morphology of cultured blood cell lines HL-60 (KCLB 10240) and J774A.1 (KCLB 40067) were observed under the inverted microscope. Ultrastructural changes of J774A.1 exposed to heat-killed P. intermedia and its SBE were investigated using transmission electron microscopy. Production of IL-$1{\beta}$ was reduced in human peripheral mononuclear cells after stimulation by sonic bacterial extracts of A. actinomycetemcomitans, P. gingivalis, and P. intermedia. Heat-killed and sonic extract of P. gingivalis inhibited the production of TNF-${\alpha}$ in peripheral mononuclear cells. Production of TNF-${\alpha}$ was inhibited in peripheral monocytes after stimulation by sonic extracts of A. actinomycetemcomitans, P. gingivalis, and P. intermedia. HL-60 and J 774A.1 cells showed granular degeneration after treatment with heat-killed and sonic extracts of A. actinomycetemcomitans, P. gingivalis, and P. intermedia Chromatin margination and shrinkage were observed in 774A.1 treated with heat-killed P. intermedia. Cell wall structure and organelles were destroyed and vacuoles were formed in cytoplasm in J774A.1 treated with P. intermedia sonic extract. These results suggest that A actinomycetemcomitans, P gingivalis and P intermedia may have an important role in the formation and progression of pulpal diseases via both modulation of production of IL-$1{\beta}$ and TNF-${\alpha}$ from blood mononuclear cells and cytopathic effects.

• Wind and Structures
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• v.15 no.4
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• pp.331-343
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• 2012

Thunderstorm downbursts are responsible for numerous structural failures around the world. The wind characteristics in thunderstorm downbursts containing vortex rings differ with those in 'traditional' boundary layer winds (BLW). This paper initially performs an unsteady-state simulation of the flow structure in a downburst (modelled as a impinging jet with its diameter being $D_{jet}$) using a computational fluid dynamics (CFD) method, and then analyses the pressure distribution on a solar updraft tower (SUT) in the downburst. The pressure field shows agreement with other previous studies. An additional pair of low-pressure region and high-pressure region is observed due to a second vortex ring, besides a foregoing pair caused by a primary vortex ring. The evolutions of pressure coefficients at five orientations of two representative heights of the SUT in the downburst with time are investigated. Results show that pressure distribution changes over a wide range when the vortices are close to the SUT. Furthermore, the fluctuations of external static pressure distribution for the SUT case 1 (i.e., radial distance from a location to jet center x=$D_{jet}$) with height are more intense due to the down striking of the vortex flow compared to those for the SUT case 2 (x=$2D_{jet}$). The static wind loads at heights z/H higher than 0.3 will be negligible when the vortex ring is far away from the SUT. The inverted wind load cases will occur when vortex is passing through the SUT except on the side faces. This can induce complex dynamic response of the SUT.

• The Transactions of the Korea Information Processing Society
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• v.6 no.7
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• pp.1832-1840
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• 1999

Since the existed Korean Web IR systems generally use boolean system, it is difficult to retrieve the information to be wanted at one time. Also, because of the feature that web documents have the frequent abbreviation and many links, the keyword extraction using the inverted document frequency extracts the improper keywords for adding ambiguous meaning problem. Therefore, users must repeat the modification of the queries until they get the proper information. In this paper, we design and implement the relevance feedback agent system for resolving the above problems. The relevance feedback agent system extracts the proper information in response to user's preferred keywords and stores these keywords in preference DB table. When users retrieve this information later, the relevance feedback agent system will search it adding relevant keywords to user's queries. As a result of this method, the system can reduce the number of modification of user's queries and improve the efficiency of the IR system.

• Earthquakes and Structures
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• v.17 no.2
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• pp.175-189
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• 2019

The aim of the study is to show the results of complex shaking table experimental investigation focused on the response of two models of cylindrical steel tanks under mining tremors and moderate earthquakes, including the aspects of diagnosis of structural damage. Firstly, the impact and the sweep-sine tests have been carried out, so as to determine the dynamic properties of models filled with different levels of liquid. Then, the models have been subjected to seismic and paraseismic excitations. Finally, one fully filled structure has been tested after introducing two different types of damages, so as to verify the method of damage diagnosis. The results of the impact and the sweep-sine tests show that filling the models with liquid leads to substantial reduction in natural frequencies, due to gradually increasing overall mass. Moreover, the results of sweep-sine tests clearly indicate that the increase in the liquid level results in significant increase in the damping structural ratio, which is the effect of damping properties of liquid due to its sloshing. The results of seismic and paraseismic tests indicate that filling the tank with liquid leads initially to considerable reduction in values of acceleration (damping effect of liquid sloshing); however, beyond a certain level of water filling, this regularity is inverted and acceleration values increase (effect of increasing total mass of the structure). Moreover, comparison of the responses under mining tremors and moderate earthquakes indicate that the power amplification factor of the mining tremors may be larger than the seismic power amplification factor. Finally, the results of damage diagnosis of fully filled steel tank model indicate that the forms of the Fourier spectra, together with the frequency and power spectral density values, can be directly related to the specific type of structural damage. They show a decrease in the natural frequencies for the model with unscrewed support bolts (global type of damage), while cutting the welds (local type of damage) has resulted in significant increase in values of the power spectral density for higher vibration modes.