• The korean journal of orthodontics
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• v.49 no.4
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• pp.246-253
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• 2019

Objective: To evaluate the effectiveness of three different caries-preventing agents on artificial caries in a Streptococcus mutans-based caries model. Methods: Sixty-five caries-free human molar enamel blocks were treated with a demineralization solution and a remineralization solution. The specimens were assigned to the following groups according to the caries-protective product applied: group A, chlorhexidine varnish; group B, fluoride-releasing chemically cured sealant; group C, fluoride-releasing lightcured sealant; group D, positive control (specimens that were subjected to de- and remineralization cycles without treatment with any caries-protective agents); and group E, negative control (specimens that were not subjected to de- and remineralization cycles). Samples in groups A-D were stored in demineralization solution with S. mutans and thereafter in artificial saliva. This procedure was performed for 30 days. Average fluorescence loss (${\Delta}F$) and surface size of the lesions were measured using quantitative light-induced fluorescence at baseline and on the 7th, 14th, and 30th days. Results: After 30 days, group A demonstrated a significant increase in ΔF and the surface size of the lesions, no significant difference in comparison with the positive control group, and a significant difference in comparison with the negative control group. Group B showed no significant changes in both parameters at any of the measurement points. While group C showed increased ${\Delta}F$ after 14 days, no significant fluorescence change was observed after 30 days. Conclusions: Both fluoride-releasing sealants (chemically or light-cured) show anti-cariogenic effects, but the use of chlorhexidine varnish for the purpose of caries protection needs to be reconsidered.

• Journal of Ocean Engineering and Technology
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• v.33 no.6
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• pp.535-546
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• 2019

The paper presents a closed-form analytical solution for the ultimate strength of sandwich panels with metal faces and an elastic isotropic core during combined in-plane compression and lateral pressure under clamped boundary condition. By using the principle of minimum potential energy, the stress distribution in the faces during uni-axial edge compression and constant lateral pressure was obtained. Then, the ultimate edge compression was derived on the basis that collapse occurs when yield has spread from the mid-length of the sides of the face plates to the center of the convex face plates. The results were validated by nonlinear finite element analysis. Because the solution is analytical and closed-form, it is rapid and efficient and is well-suited for use in practical structural design methods, including repetitive use in structural optimization. The solution applies for any elastic isotropic core material, but the application that stimulated this study was an elastomer-cored steel sandwich panel that had excellent energy absorbing and protective properties against fire, collisions, ballistic projectiles, and explosions.

• Corrosion Science and Technology
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• v.19 no.6
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• pp.281-287
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• 2020

Chloride ion is one of the most important corrosive agents in atmospheric corrosion, especially in marine environments. It has high adsorption rate and increases the conductivity of electrolytes. Since chloride ions affect the protective properties and the surface composition of the corrosion product, they increase the corrosion rate. A low level of chloride ions leads to uniform corrosion, whereas a high level of chloride ions may induce localized corrosion. However, higher solution temperatures tend to increase the corrosion rate by enhancing the migration of oxygen in the solution. This work focused on the effect of NaCl concentration and temperature on galvanic corrosion between A516Gr.55 carbon steel and AA7075T6 aluminum alloys. When AA7075T6 aluminum alloy was galvanically coupled to A516Gr.55 carbon steel, AA7075T6 was severely corroded regardless of NaCl concentration and solution temperature, unlike the corrosion properties of single specimen. The combined effect of surface treatment involving carbon steel and aluminum alloy on corrosion behavior was also discussed.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.10
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• pp.516-523
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• 2000

In this paper, intelligent methods using digital protective relay in power supervisory control system is developed in order to protect power systems by means of timely fault detection and diagnosis during operation for induction motor which has various load environments and capacities in power systems. The spectrum pattern of input currents was used to monitor to state of induction motors, and by clustering the spectrum pattern of input currents, the newly occurrence of spectrums pattern caused by faults were detected. For diagnosis of the fault detected, the fuzzy fault tree was derived, and the fuzzy relation equation representing the relation between an induction motor fault and each fault type, was solved. The solution of the fuzzy relation equation shows the possibility of each fault's occurring. The results obtained are summarized as follows: 1) The test result on the basis of KEMC1120 and IEC60255, show that the operation time error of the digital motor protective relay is improved within ${\pm}5%$. 2) Using clustering algorithm by unsupervisory learning, an on-line fault detection method, not affected by the characteristics of loads and rates, was implemented, and the degree of dependency by experts during fault detection was reduced. 3) With the fuzzy fault tree, fault diagnosis process became systematic and expandable to the whole system, and the diagnosis for sub-systems can be made as an object-oriented module.

• Korean Journal of Acupuncture
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• v.17 no.1
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• pp.179-190
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• 2000

This study was undertaken to determine whether Juglandis semen extract solution (JLS solution) exerts protective effect against oxidant-induced inhibition of glutamate uptake by synaptosomes. Synaptosome was prepared from rabbit brain cortex. Glutamate uptake increased by incubation time during 10 minutes, which was significantly inhibited by 1mM t-buthylhydroperoxide(t-BHP). JLS solution prevented t-BHP-induced inhibition of glutamate uptake in a dose-dependent manner. t-BHP reduced glutamate uptake in dose-dependent fashion, which was significantly prevented by 2% JLS solution. t-BHP(1mM) and $ascorbate/Fe^{2+}(50/1{\mu}M)$ increased lipid peroxidation in synaptosomes by 5-fold, and it was significantly prevented by 2% JLS solution. $HgCl_2(0.1mM)$ inhibited glutamate uptake and increased lipid peroxidation. These changes were prevented by 2% JLS solution. Synaptosomal Na-K-ATPase activity was inhibited by t-BHP(1mM) and $H_2O_2(50mM)$, which was prevented by 2% JLS solution. The results indicate that JLS solution prevents oxidant-induced inhibition of glutamate by synaptosomes, and this may result from inhibition of lipid peroxidation induced by oxidants.

• Textile Coloration and Finishing
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• v.10 no.2
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• pp.29-36
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• 1998

Poly(L-lactide) microcapsules containing hydrophilic penetrate were prepared by interfacial precipitation method through solvent evaporation from w/o/w emulsion. Effect of four determinative process parameters on the particle size distributions, morphologies, and release properties of microcapsules coated with poly(L-lactide) was investigated. Moreover, susceptible functional cotton fabrics treated with the mentioned microcapsules were prepared and laundry test up to 15 times were done to determine fastness properties. As a result, the prepared poly(L-lactide) microcapsules with a more sharp-distributive, rounder, and more permeable membranes could be prepared by means of protective colloid concentration, solution volume and stirring rate.

• The Korea Journal of Herbology
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• v.23 no.3
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• pp.1-9
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• 2008

Objectives : This research was performed to investigate protective effect of Sophora Subprostrata against transient global ischemic damage after 5-min two vessel occlusion. Methods : Gerbils were divided into three groups: Normal group, 5-min two vessel occlusion (2VO) group, Sophora Subprostrata administrated group after 2VO. The CCAs were occluded by microclip for 5min. Sophora Subprostrata was administrated orally(12mg/ml) for 7 days after 2VO. The histological and immunohistochemistrical analysis was performed at 72 hours and 7 days after the surgery each. For histological analysis, the brain tissue was stained with 1% cresyl violet solution and Immunohistochemistry for BAX and Bcl-2 was carried out to examine effect of Sophora Subprostrata on ischemic brain tissue. Results : The results showed that (1) Sophora Subprostrata has the protective effect against ischemia in CA1 area of the gerbil hippocampus 7 days after 5-minute occlusion, (2) the treatment of Sophora Subprostrata inhibits the expression of Bax relatively after 2VO-induced ischemia. That protective effect of the Sophora Subprostrata seems to be performed by regulating the proportion of Bax and Bcl-2 protein, (3) in hypoxia/reperfusion model using PC12 cell, the Sophora Subprostrata extract has the protective effect against ischemia in the dose of $2{\mu}/m{\ell}$ and $20{\mu}/m{\ell}$.This study suggests that Sophora Subprostrata has neuroprotective effect against neuronal damage following cerebral ischemia in vivo with a widely used experimental model of cerebral ischemia in Mongolian gerbils and that Sophora Subprostrata regulates the proportion of Bax and Bcl-2 protein following ischemia. And, Sophora Subprostrata extract has protective effects also on a hypoxia/reperfusion cell culture model using PC12 cell. Conclusions : Sophora Subprostrata has protective effects against ischemic brain damage at the early stage of ischemia.

• Journal of Ocean Engineering and Technology
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• v.24 no.5
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• pp.60-66
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• 2010

Zinc has a number of characteristics that make it well suited for use as a coating to protecting iron and steel products from corrosion. Its excellent corrosion resistance in most environments accounts for its successful use as a protective coating on a variety of products and in many exposure conditions. The excellent field performance of zinc coatings results from their ability to form dense, adherent films that corrode at a rate that ranges from 1% to 10% of the corrosion rate of ferrous materials, depending on the environment. Recently, EU RoHS and EU ELV prohibited the use of materials that adversely affect the environment, such as Pb, Hg, Cd, and $Cr^{+6}$. In this study, environmentally-friendly, Cr-free solutions (epoxy solution, acrylic solution, and urethane solution S-700) and organic/inorganic solution with Si; LRO-317) were used to evaluate the corrosion resistance of zinc-coated steel subjected to a saltwater spray for 72 hours. The coating of urethane solution (S-700) was best among the three kinds of solution with heat treatment during five minutes at $190^{\circ}F$. Test specimens with S-700 and LRO-317 coating were heat treated in a drying oven at 170, 180, 190, 200, and $210^{\circ}C$ for five minutes. The results show that the optimum corrosion resistance was $190^{\circ}C$ in EGI and $170^{\circ}C$ in HDGI, respectively.

• Proceedings of the KAIS Fall Conference
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• 2009.12a
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• pp.318-321
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• 2009

The Efficacy of PSB-2061, was investigated in comparision with predinisolone in acetic acid and Picrylsulfonic acid solution (TNBS)-induced rat inflammatory bowel disease (IBD) for 5 days. 5 % TNBS solution were administered with polyethylene (P.E) tube inserted to rats intracolon, which causing colitis to the rats. The TNBS control group (the saline treated colitic rat) exhibited ulceration and inflammation of the distal colon with formation of granuloma and pathologic connections. We checked the inflammatory parameters like rat's weight, food intake quantity change during administration. After 5 days, we sacrificed the rats and checked the colon's length, ulcer and pathologic condition. Oral treatment with PSB-2061 resulted in significant recovery of macroscopic parameters like weight and diet intake change. Especially, PSB-2061 extract had a more potent effect than $mesalazine^{(R)}$ on macroscopic colonic damage score. We can suggest that PSB extract could be a promising drug in the treatment of IBD.

• Journal of Chest Surgery
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• v.23 no.6
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• pp.1090-1106
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• 1990

This study was undertaken to investigate whether adenosine administered during cardioplegic arrest could enhance myocardial protection and improve recovery of function after ischemia. Isolated Langendorff-perfused rat hearts were subjected to 40 minutes of normothermic [37oC] ischemia. Control hearts [n=10] received modified St. Thomas’ cardioplegic solution, and the remaining hearts received modified St. Thomas’ cardioplegic solution with either 20 \ulcornerM [n=10], 200 \ulcornerM [n=10] adenosine. After ischemia of 40 minutes and 30 minutes of reperfusion, left ventricular contractility was superior in all groups of adenosine-treated hearts compared with control hearts. Furthermore, there was a significant incremental increase in functional recovery with increasing dose of adenosine. Post-ischemic diastolic stiffness was significantly better in all adenosine groups compared with controls. No differences were noted in coronary flow or myocardial water content between adenosine-treated and control hearts. These data demonstrate that adenosine administered in these concentrations provides myocardial protection, preservation of myocardial ATP and creatine phosphokinase and improved post-ischemic functional hemodynamic recovery after normothermic ischemia, presumably metabolically by reducing depletion of adenosine triphosphate, inducing rapid cardiac arrest and enabling improved post-ischemic recovery.