• Restorative Dentistry and Endodontics
• /
• v.26 no.5
• /
• pp.418-435
• /
• 2001

Root canal preparation process is of utmost importance in successful treatment of root canal. Also, one of the most important purpose of the root canal preparation is to enlarge the root canal three dimensionally without changing the curvature of the root canal However as the curvature of the root canal increases, there are many difficulties involved in formation of optimum root canal. Therefore in order to solve the above mentioned problems, new developments in methods of root canal preparation and equipments for such purposes were made. Recently, vigorous studies about newly introduced engine-driven nickel-ti-tanium rotary file are conducted. As shown in research results to dates, it is well established that the use of nickel-titanium file is better suited for curved root canal than stainless steel file in maintaining the curvature or root canal and reducing the deformation of root canal. However it is also acknowledged that there are a few discrepancies in research results according to protocol, due to failure to remove variables in experiments. In addition, although it is recommended by the manufacturer that the GT rotary file should maintain a low rotational speed of 150~350rpm and 'light pressure' as light as not to break the lead of a pencil, academic studies about the vertical force which is not yet standardized are not sufficiently explored. Therefore, this research devised and utilized a special research equipment to standardize the appropriate range of vertical force for GT rotary file through experiments by breaking of the lead of a pencil as expressed by the manufacturer and to accurately measure factors involved through repeating and recreating the environment of root canal preparation. Forming nine experimental groups by varying the vertical forces (150g. 220g, 300g) and rpm (150rpm, 250rpm, 350rpm), the effects of changing vertical forces and rpm on working efficiency were measured in terms of time expended in root canal preparation by crown-down method using a transparent resin block with 35 degree curvature and GT rotary file (z-test). The following research using this special research equipment that involved nine experimental groups and varying the vertical force for root canal preparation from 300g which is within the normal vertical force range to 700g and 1000g which fall outside the normal rpm range. The results were as follows : 1. Analysis of the experiment results revealed that the time spent in root canal preparation decreased as the vertical forces and rpm increased (p<0.05). Also, the effects of rpm were greater than those of the vertical forces within the normal vertical force range ($\beta$-weight test). 2. Observation of the deformation of GT rotary file revealed that deformation increases in a direct correlation with the vertical force increase and in a reverse correlation with the rpm decrease. In the case of the vertical forces close to the normal range, the probability of GT rotary file deformation were quite different depending on the rpm changes. In the case of greater vertical forces, the occurrences of deformation of the file were more frequent regardless of the rpm changes. 3. Deformation and breakage of file were also commonly observed in the expended time measurement experiments and GT rotary file deformation experiments in which low speed rpm (150rpm) was used and at the curved portion of the resin block.

• Molecules and Cells
• /
• v.19 no.1
• /
• pp.114-123
• /
• 2005

Nitropyrene, the predominant nitropolycyclic hydrocarbon found in diesel exhaust, is a mutagenic and tumorigenic environmental pollutant that requires metabolic activation via nitroreduction and ring oxidation. In order to determine the role of ring oxidation in the mutagenicity of 1-nitropyrene, its oxidative metabolites, 1-nitropyrene 4,5-oxide and 1-nitropyrene 9,10-oxide, were synthesized and their mutation spectra were determined in the coding region of hprt gene of CHO cells by a PCR amplification of reverse-transcribed hprt mRNA, followed by a DNA sequence analysis. A comparison of the two metabolites for mutation frequencies showed that 1-nitropyrene 9,10-oxide was 2-times higher than 1-nitropyrene 4,5-oxide. The mutation spectrum for 1-nitropyrene 4,5-oxide was base substitutions (33/49), one base deletions (11/49) and exon deletions (5/49). In the case of 1-nitropyrene 9,10-oxide, base substitutions (27/50), one base deletions (15/50), and exon deletions (8/50) were observed. Base substitutions were distributed randomly throughout the hprt gene. The majority of the base substitutions in mutant from 1-nitropyrene 4,5-oxide treated cells were $A{\rightarrow}G$ transition (15/33) and $G{\rightarrow}A$ transition (8/33). The predominant base substitution, $A{\rightarrow}G$ transition (11/27) and $G{\rightarrow}A$ transition (8/27), were also observed in mutant from 1-nitropyrene 9,10-oxide treated cells. The mutation at the site of adenine and guanine was consistent with the previous results, where the sites of DNA adduct formed by these compounds were predominant at the sites of purines. A comparison of the mutational patterns between 1-nitropyrene 4,5-oxide and 1-nitropyrene 9,10-oxide showed that there were no significant differences in the overall mutational spectrum. These results indicate that each oxidative metabolite exhibits an equal contribution to the mutagenicity of 1-nitropyrene, and ring oxidation of 1-nitropyrene is an important metabolic pathway to the formation of significant lethal DNA lesions.

• Journal of Music and Human Behavior
• /
• v.9 no.2
• /
• pp.53-67
• /
• 2012

Improvisational music therapy is known to promote social engagement in children with autism. This study investigated salient features that characterize the engagement of the child with autism and the therapist in improvisational music therapy. Through video analysis of the children's behavior, this study sets out to investigate what engages children with autism into mutual play with the therapist in improvisational music therapy by measuring the shared musical elements between the child and the therapist during musical synchronicity episodes and the children's choice of instruments. A repeated measures, a crossover design was employed in two different conditions (n = 10). Children were randomly assigned into two groups; group 1 participated music therapy first, followed by play therapy second. Group 2 followed the reverse order. Specific target behaviors were analyzed in the selected sessions 1, 4, 8 and 12. As expected, improvisational music therapy produced markedly more and longer events of musical synchronicity in children with autism than the play sessions with toys (p < .001). Rhythm and dynamic appeared to be the two most salient elements during musical synchronicity events between the child and the therapist. Observational findings confirmed that horns and whistles were the most frequently selected instruments in music therapy, whereas a dollhouse set was in play therapy by children with autism. The clinical implications and the details of these findings are discussed further.

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

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.35 no.2
• /
• pp.155-161
• /
• 2002

Tetraselmis suecica (T. suecica) of Prasinophyta was selected because the growth rate is comparatively higher and the culturing is also easy. In order to investigate antioxidative activity, the soluble elements of T. suecica were fractionated using water and organic solvents such as methanol, hexane, chloroform, ethylacetate and butanol. The chloroform fraction of T. suecica showed strong antioxidative activity. The potential antioxidative activity was detected in hexane: ethylacetate (1:5) once used the fractions by different mixtures of organic solvents. This fraction was further purified by preparative thin layer chromatography (PTLC) and repeated reverse-phase HPLC. On the basis of chemical and spectroscopic evidences obtained by UV, FT-IR, FAB-MS and NMR, the compound purified from T. suecica was identified as pheophorbide-a. The antioxidative activity of the compound was comparable to that of $\alpha$-tocopherol and could be act as an antioxidant in foods.

• Culinary science and hospitality research
• /
• v.15 no.1
• /
• pp.128-136
• /
• 2009

In this study, Korean wheat wet noodles were prepared with 1, 3, 5, and 7% pomegranate cortex powder(PGCP). The samples and a control were compared in terms of quality characteristics, including cooking properties, colors, textural characteristics, and sensory evaluation in order to determine the optimal ratio of PGCP in the formulation. With regard to the cooking properties, weight, volume, and water absorption decreased with PGCP content increased. As for colors, the PGCP content L, a, b value increased. For the textural characteristics, springiness and cohesiveness were not significantly different among the samples. The PGCP samples had significantly higher hardness, chewiness, brittleness, and gumminess than the control group. However, strength showed the reverse effect. In the sensory evaluation, the control group had significantly higher scores in colors, texture, and chewiness as compared to the PGCP samples. Overall acceptability decreased with PGCP content increased while bitterness, astringency, and off-flavor increased. Furthermore, saltiness and gumminess were not significantly different among the samples. In conclusion, the results show that 1% of PGCP was proved very useful as a substitute for Korean wheat flour in the production of wet noodles, providing good nutritional and functional properties.

• Tuberculosis and Respiratory Diseases
• /
• v.77 no.2
• /
• pp.73-80
• /
• 2014

Background: Low levels of serum vitamin D is associated with several lung diseases. The production and activation of matrix metalloproteinases (MMPs) may play an important role in the pathogenesis of emphysema. The aim of the current study therefore is to investigate if vitamin D modulates the expression and activation of MMP-2 and MMP-9 in human lung fibroblasts (HFL-1) cells. Methods: HFL-1 cells were cast into three-dimensional collagen gels and stimulated with or without interleukin-$1{\beta}$ (IL-$1{\beta}$) in the presence or absence of 100 nM 25-hydroxyvitamin D (25(OH)D) or 1,25-dihydroxyvitamin D ($1,25(OH)_2D$) for 48 hours. Trypsin was then added into the culture medium in order to activate MMPs. To investigate the activity of MMP-2 and MMP-9, gelatin zymography was performed. The expression of the tissue inhibitor of metalloproteinase (TIMP-1, TIMP-2) was measured by enzyme-linked immunosorbent assay. Expression of MMP-9 mRNA and TIMP-1, TIMP-2 mRNA was quantified by real time reverse transcription polymerase chain reaction. Results: IL-$1{\beta}$ significantly stimulated MMP-9 production and mRNA expression. Trypsin converted latent MMP-2 and MMP-9 into their active forms of MMP-2 (66 kDa) and MMP-9 (82 kDa) within 24 hours. This conversion was significantly inhibited by 25(OH)D (100 nM) and $1,25(OH)_2D$ (100 nM). The expression of MMP-9 mRNA was also significantly inhibited by 25(OH)D and $1,25(OH)_2D$. Conclusion: Vitamin D, 25(OH)D, and $1,25(OH)_2D$ play a role in regulating human lung fibroblast functions in wound repair and tissue remodeling through not only inhibiting IL-$1{\beta}$ stimulated MMP-9 production and conversion to its active form but also inhibiting IL-$1{\beta}$ inhibition on TIMP-1 and TIMP-2 production.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.6
• /
• pp.1407-1412
• /
• 2014

In order to improve spectrum sensitivity of photodiode for detection of the laser at 850 nm ~ 1000 nm of near-infrared wavelength band, this study has produced silicon-based fast film PIN photodiode and analyzed electrical and optical properties. The manufactured device is packaged in TO-18 type. The electrical properties of the dark currents both Anode 1 and Anode 2 have valued of approximately 0.055 nA for 5 V reverse bias, while the capacitance showed 19.5 pF at frequency range of 1 kHz and about 19.8 pF at the range of 200 kHz for 0 V. In addition, the rising time of output signal was verified to have fast response time of about 30 ns for 10 V. For the optical properties, the best spectrum sensitivity was 0.66 A/W for 880 nm, while it was relatively excellent value of 0.45 A/W for 1,000 nm.

• Journal of Service Research and Studies
• /
• v.5 no.2
• /
• pp.71-81
• /
• 2015

The RSA public key encryption algorithm, a few, key generation, factoring, the Euler function, key setup, a joint expression law, the application process are serial indexes. The foundation of such algorithms are mathematical principles. The first concept from mathematics principle is applied from how to obtain a minority. It is to obtain a product of two very large prime numbers, but readily tracking station the original two prime number, the product are used in a very hard principles. If a very large prime numbers p and q to obtain, then the product is the two $n=p{\times}q$ easy station, a method for tracking the number of p and q from n synthesis and it is substantially impossible. The RSA encryption algorithm, the number of digits in order to implement the inverse calculation is difficult mathematical one-way function and uses the integer factorization problem of a large amount. Factoring the concept of the calculation of the mod is difficult to use in addition to the problem in the reverse direction. But the interests of the encryption algorithm implementation usually are focused on introducing the film the first time you use encryption algorithm but we have to know how to go through some process applied to the field work This study presents a field force applied encryption process scheme based on public key algorithms attribute diagnosis.

• Korean Business Review
• /
• v.13
• /
• pp.107-132
• /
• 2000

The entry of large discount stores such as E-mart, LG mart, Magnet etc. into small cities have had a profound impact on the business of small-sized retailers. Now, it becomes the matter of survival for small-sized retailers and it is almost impossible to reverse those trends. Without satisfying consumers' various needs and wants, retailers can not survive. Therefore, it is extremely important to understand retail competition from the perspective of consumers in order for retailers to survive in the turbulent environment. The previous research studies on retail competition have focused on the comparison among different types of retailers with respect to strategic retail mix variables. However, they do not consider the competitive aspects of consumers' sides. In addition, we do not fully understand the meaning of "shopping." Shopping means hedonic shopping as well as utilitarian shopping. Utilitarian aspects are important but consumers also prefer' hedonic aspects too. That is the reason that traditional retailers such as small-sized retailers can not compete with modem and large retailers. We use three different methods to identify the macro and competitive structure. of retailing with respect to shopping. Factor analysis, multidimensional scaling, and multiple correspondence analysis are used to produce perceptual mapping of retail competition. Department store and large discount store are identified as close competitors but both might have an indirect impact on small-sized retailers through demand shift toward high end retailers.