• Journal of Life Science
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• v.22 no.8
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• pp.1046-1051
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• 2012

In order to investigate the changes in bioactive materials induced in goldfish brains by $^{18}F$ irradiation, the variations in the neurotransmitter levels in the whole brain were studied. The distance between the goldfish and 580 mCi of $^{18}F$ was about 4 cm, and the exposure lasted for 4 hrs. The absorption level calculated based on the distance, exposure time, and half-life of $^{18}F$ was approximately 2 Gy. After sacrifice by $^{18}F$ irradiation or untreated conditions, ten brains were dissected or immediately frozen, respectively. The tissues were extracted in acetic acid. After lyophilization, the samples were dissolved in distilled water and were further purified on a reverse-phase HPLC column. There were no differences in the intensities of the bioactive materials between $^{18}F$-exposed goldfish and control goldfish, while the only peak corresponded to 13 min, which indicated a significant increase in the irradiated brains. Our analysis has found that this compound is tryptophan. This result suggests that $^{18}F$ leads to changes in a classical neurotransmitter, tryptophan, in both the brains of control goldfish and goldfish contaminated by irradiation.

• Journal of Applied Biological Chemistry
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• v.54 no.3
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• pp.159-165
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• 2011

Rosmarinus officinalis extracts had a significant antimicrobial activity against Helicobacter pyori. Total phenolic contents and inhibition zone of rosemary extracts were estimated to be 25.7 mg/g and 14 mm at $200{\mu}g/mL$ of phenolic contents, respectively. The Sephadex LH-20 and MCI-gel CHP-20 column chromatographic separations for the phenolic extracts from R. officinalis leaves led to isolation of five acids, whose structures were determined as protocatechuic acid (A), coumaric acid (B), caffeic acid (C), chlorogenic acid (D), and rosmarinic acid (E), from interpretation of spectroscopic data including nagative fast atom bombardment (FAB)-mass, $^1H$-NMR, $^{13}C$-NMR, and IR. All isolated compounds were tested for antimicrobial activity against H. pyori. The purified single compound showed less antimicrobial activity against H. pylori than the mixed purified compounds, which generate A+B, A+E, C+D, C+E (each $200{\mu}g/disc$) excellent as large clear zone by synergy effect. These results indicate rosemary extracts are preventive agents against H. pyori.

• Journal of Biosystems Engineering
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• v.38 no.4
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• pp.240-247
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• 2013

Purpose: This study was conducted to develop a rubber-crawler type vehicle as a traveling device for harvesting water-dropwort cultivated in water contained paddy rice field in winter season. Methods: A commercial rubber-crawler type vehicle was used to investigate application of rubber crawler to the paddy rice field as preliminary test. As the result of the preliminary test, a both prototype traveling device with rubber crawlers for a water-dropwort harvest was designed with inclination of $45^{\circ}$ at the front-end and rear-end of crawler under the basic water depth of 0.6 m in the paddy rice field. The device was fabricated and attached to the experimental harvesting test devices on the front of the prototype vehicle. The size of the prototype crawler vehicle with a harvesting part is $2,800{\times}1,460{\times}1,040 $ (mm) ($L{\times}W{\times}H$) with weight of 9.21 kN (maximum). Sizes of the crawler of prototype vehicle are ground contact length of 900 mm, width of 180 mm, height of 1,070 mm and distance between center to center of crawlers of 720 mm. The side-overturn angle of the prototype was $26.4^{\circ}$. Results: Driving performance of the prototype vehicle in water contained paddy field were good at both forward and reverse (backward) directions as weights were applied. The drawbar pull and the maximum sinking depth of the prototype vehicle were 3.5 kN and 0.13 m respectively at water depth of 0.5 m, when the weight and bearing capacity of the prototype rubber crawler in the paddy field were 8.51 kN and 26.3 $kN/m^2$, respectively. Conclusions: Results of the driving test performance of the prototype crawler in paddy rice field at the water depth of 0.5 m were satisfactory. The prototype had enough drawbar pull and driving ability in the deep water contained paddy field.

• Journal of Conservation Science
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• v.36 no.5
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• pp.306-314
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• 2020

The use of synthetic resins in ceramic restoration poses several challenges, including aging and potential damage to artifacts, which has raised the need to investigate new materials and restoration methods. This study set out to incorporate full color 3D printing into the 3D digital technology-based restoration method, an emerging approach currently being researched, and to print out missing parts with color information. After examining material physical properties with an experiment, the investigator printed out missing parts from a white porcelain vessel and grayish-blue-powdered celadon plate and compared them in chromaticity and brilliance. The experimental results show that the outputs had comparable tensile strength to the original restoration materials, whereas the recorded compressive strength was approximately 1.4~2 times higher than that of the original restoration materials. According to the NIST table of color difference values, the white porcelain vessel was visible at ΔE^*ab 1.55, and the grayish-blue-powdered celadon plate was perceivable at 3.34. Even though it was impossible to express the colors accurately owing to printer limitations, this non-contact approach reduced the possibility of damage to the minimum. In conclusion, it can be applied to objects with a high chance of damage or generate display effects through purposeful color differentiation in missing parts.

• Restorative Dentistry and Endodontics
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• v.34 no.1
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• pp.1-7
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• 2009

The purpose of this study was to compare the stress distributions of NiTi rotary instruments based on their cross-sectional geometries of triangular shape-based cross-sectional design, S-shaped cross-sectional design and modified rectangular shape-based one using 3D FE models. NiTi rotary files of S-shaped and modified rectangular design of cross-section such as Mtwo or NRT showed larger stress change while file rotation during simulated shaping. The stress of files with rectangular cross-section design such as Mtwo, NRT was distributed as an intermittent pattern along the long axis of file. On the other hand, the stress of files with triangular cross-section design was distributed continuously. When the residual stresses which could increase the risk of file fatigue fracture were analyzed after their withdrawal. the NRT and Mtwo model also presented higher residual stresses. From this result, it can be inferred that S-shaped and modified rectangular shape-based files were more susceptible to file fracture than the files having triangular shape-based one.

• 한국문화재보존과학회:학술대회논문집
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• 2004.10a
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• pp.15-24
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• 2004

The Seokgatap pagoda composed of mainly alkali granite and other minor pink-feldspar granite, fine-grained granite, granodiorite, diorite, gabbro, and tuff. Despite the small loss and damage derived from joints, its peel-off and exfoliation are serious enough to cause the heavy deterioration on the stone surface. The chemical and petrological weathering has partly replaced the original rock-forming minerals with clay minerals and iron oxyhydroxides. Based on the petrogenesis, rock materials of the pagoda is very similar to rocks of Dabotap pagoda and the Namsan granite in the Gyeongju. The central fart of the pagoda has sunken highly, which caused all the corners to split and the structural transformation to become worse. The reverse V-shaped gaps between the materials have broken stones filled in a coarse way. The iron plates inserted between the upper flat stone laid on other stones and tile pagoda body in the north and east side has been exposed in the air and corroded, discoloring of the adjacent stones. The overall diagnosis of the Seokgatap pagoda is the deteriorated functions of the stone materials, which calls for a long-term monitoring and plans to reinforce the stone surfaces. But the main body including the pagoda roof stone needs washing on a regular basis, and the many different cracks should be fixed with glue by using the fillers or hardeners designed for stone cultural properties after removing the cement mortar. In case of the replacement of the stone materials with new stones, it's necessary to examine the pagoda for the center of gravity and support intensity of the materials. The structural stability of the pagoda can be attained by taking a reinforce measure in geotechnical engineering and making a drainage. The ground humidity, which has aggravated weathering and structural instability, should be resolved by setting up a humidity reduction facility. The contamination of lichens and bryophyte around the pagoda and on the surface is serious. Thus biochemical treatments should be given too in order to prevent further biological damages and remove the vegetation growing on the discontinuous planes.

• Journal of Conservation Science
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• v.31 no.2
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• pp.131-145
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• 2015

Cultural assets restoration is being considered highly as a practical way to extend the lifespan of damaged cultural assets and re-highlight their value. However, restoration process has been mostly dependent on the manual work involving the experience and skill of a person performing restoration, thereby requiring much time and effort. In recent, it became possible to apply a method allowing restoration to be performed more accurately and easily according to the material characteristics and shape of cultural assets. Namely, it is to use a method of printing out the 3D shape data computed in computer as real object by using 3D printer for the restoration that has been performed manually. The missing part of a cultural asset is computed into computer data first and is printed out by using 3D printer to undergo a simple shaping process. The result of 3D printer application showed that repetitive output and shape and figure revision of digital data were possible, and it was possible to improve the degree of completedness of restoration through test output using various types of restoration materials using various materials. For the purpose of verifying the possibility of applying 3D printer to restore missing part of earthenware, two pieces of modern reproductions, namely, the Seven Treasure Incense Burner and Earthenware with Wagon Wheel Decoration, were artificially damaged. The restoration result showed that compared to manual work, it showed better effectiveness in curtailing work time and reproducing accurate shape. On the other hand, secondary manual work was slightly needed for detailed binding and to vividly express surface texture.

• Journal of the Korean Chemical Society
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• v.25 no.2
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• pp.110-118
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• 1981

Kinetics and mechanism for the reaction of substituted phenacyl bromides with substituted pyridines have been determined at 25, 35 and $45^{\circ}C$ in methanol and dimethylformamide by the conductivity method. The rate constants for the reaction of various pyridines with phenacyl bromide shown that electron-donating substituents in the pyridine increase the rate, while electron-attracting one decrease in both solvents. The effect of substituents in substrate, the rate being increased by electron-attracting substituents. This is as expected for nucleophilic attack of amines on the carbon atom. Isokinetic and $Br{\psi}nsted$ linear relationship were shown in the reaction of phenacyl bromide with pyridines in both solvent in which isokinetic temperature were obtained 614, $202^{\circ}K$ and ${\beta}$ values were 0.29, 0.36 in methanol and dimethylformamide respectively. In the case of the reaction of substituted phenacyl bromide with pyridines, isokinetic temperature decreases with increasing electron-attracting ability of the substituents in the phenacyl bromide, while the ${\beta}$ values were reverse. From the above results, it can be inferred that N…C bond formation decreases progressively from p-chloro- to p-methoxyphenacyl bromide and the bond formation predominates in DMF than methanol. The ${\rho}$ values of Hammett equation of the reaction of phenacyl bromide with substituted pyridines are negative in both solvent, but its value was larger negative in DMF than methanol and the ${\rho}$ value of that of substitutted substrates with pyridine was 0.3, the low value is ascribed to direct $S_N2$ attack of the nitrogen atom in pyridine ring at the methylene carbon.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.3
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• pp.301-307
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• 2010

Actuation using a shape memory alloy (SMA) is considered to be an important technology that will play a leading role in market for next-generation medical devices because an SMA actuator can accurately imitate skillful and delicate hand movements. However, SMA actuators have not been successfully used because of problems in control design caused by the nonlinear hysteresis effect of SMA, which leads to inaccuracies in control systems. In order to overcome the effect, the authors invented a SMA actuator, which could actively and rapidly cool down and heat up, by combining a SMA catheter and a TE module using the Peltier effect. In order to evaluate the TE characteristics of our TE module system, the changes in the temperature with 1) incremental increases in a continuous electric current and 2) the appearance of a discontinuous constant or reverse current are discussed in this paper.

• Journal of Gifted/Talented Education
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• v.25 no.5
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• pp.731-747
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• 2015

The purpose of this RSP program is to enhance the invention gifted students' creative thinking and self-efficacy in studying. This program has 20 subcategories and interesting activities attracting students' attentions which are based on TRIZ's 40 principles of invention. 3-Steps to learning, which are - experiencing, recognizing, and inventing are arranged as teaching methods of RSP program. In the first step, experiencing, students are motivated and get a glimpse of the principles of invention while experiencing innovative products. In the next step, recognizing, students grasp the related scientific principles from the products. In the last step, inventing, students are given keys to solutions for problematic situations and then they create new ideas after repetitive encounters with several products made by similar principles. RSP program is different from other programs in that it has this 'inventing' step, where students can create new ideas based on related basic knowledge. In conclusion, RSP program is systematically well organized with 4 steps(purpose, contents, teaching method and evaluation) and is shown to enhance invention gifted students' creativity and self efficacy in studying. Therefore, the RSP program is shown to be a reliable and useful program, and may be used in the classes for positive results.