• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.3
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• pp.404-410
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• 2014

The effects of treatment with various complex carbohydrases such as Pectinex, Celluclast, Viscozyme, and Ultraflo on the physiochemical properties, polyphenol extraction yields and antioxidant activities of pear peel and pear core were investigated. When pear peel and pear core were treated with complex carbohydrases, the soluble solid content of peel increased, whereas it did not change significantly in the case of pear core. When pear peel and pear core were treated with Pectinex, significant improvement of soluble solid content was observed along with the highest extraction yield of reducing sugar content. Total sugar content increased in most of the enzyme treatment groups. In the case of pear peel, the Viscozyme treatment group showed the highest total polyphenol contents, total flavonoid contents, DPPH radical scavenging activity, ABTS radical scavenging activity, and SOD-like activity. When the flesh and core of pear were treated with Celluclast, total polyphenol contents increased. All enzyme treatment groups except for the Ultraflo treatment group showed increases in total flavonoid contents. With regard to pear flesh, the Celluclast group showed the highest DPPH radical scavenging activity. When pear core was treated with the four complex carbohydrases, DPPH radical scavenging activity and ABTS radical scavenging activity did not increase significantly. However, the SOD-like activity of all enzyme treatment groups significantly increased. Consequently, dry matter and soluble solid contents, polyphenol content, and antioxidant activity of pear peel and core could be improved by complex carbohydrase treatment.

• Journal of KIISE:Information Networking
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• v.30 no.3
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• pp.329-342
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• 2003

Most of the existing multicast routing protocols for ad-hoc networks do not take into account the efficiency of the protocol for the cases when there are large number of sources in the multicast group, resulting in either large overhead or poor data delivery ratio when the number of sources is large. In this paper, we propose a multicast routing protocol for ad-hoc networks, which particularly considers the scalability of the protocol in terms of the number of sources in the multicast groups. The proposed protocol designates a set of sources as the core sources. Each core source is a root of each tree that reaches all the destinations of the multicast group. The union of these trees constitutes the data delivery mesh, and each of the non-core sources finds the nearest core source in order to delegate its data delivery. For the efficient operation of the proposed protocol, it is important to have an appropriate number of core sources. Having too many of the core sources incurs excessive control and data packet overhead, whereas having too little of them results in a vulnerable and overloaded data delivery mesh. The data delivery mesh is optimally reconfigured through the periodic control message flooding from the core sources, whereas the connectivity of the mesh is maintained by a persistent local mesh recovery mechanism. The simulation results show that the proposed protocol achieves an efficient multicast communication with high data delivery ratio and low communication overhead compared with the other existing multicast routing protocols when there are multiple sources in the multicast group.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.2
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• pp.127-133
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• 2019

Purpose: The purpose of present study was to investigate fracture strength and mode of failure of endodontically treated teeth restored with metal cast post-core system, prefabricated fiber post system, and newly introduced polyetherketoneketone (PEKK) post-core system. Materials and methods: A total of 21 mandibular premolar were randomly grouped into 3 groups of 7 each according to the post material. Group A was for metal cast post core; Group B for prefabricated glass fiber post and resin core; and Group C for milled PEKK post cores. All specimens were restored with metal crown. The fracture strength of each specimen was measured by applying a static load of 135-degree to the tooth at 2 mm/min crosshead speed using a universal testing machine. After the fracture strength measurement, the mode of failure was observed. The results were analyzed using Kruscal-Wallis test and post hoc Mann-Whitney U test at confidence interval ${\alpha}=.05$. Results: Fracture resistance of PEKK post core was lower than those of cast metal post and fiber reinforced post with composite resin core. In the aspect of fracture mode most of the root fracture occurred in the metal post core, whereas the post detachment occurred mainly in the fiber reinforced post. In the case of PEKK post core, teeth and post were fractured together. Conclusion: It is necessary to select appropriate materials of post for extensively damaged teeth restoration and clinical application of the PEKK post seems to require more research on improvement of strength.

• The Journal of the Korea Contents Association
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• v.13 no.11
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• pp.800-806
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• 2013

The purpose of this study was to evaluate the marginal fitnesses on the effect of span length of bridge and the marginal gaps within the clinically allowed range. The samples were fabricated with zirconia core using CAD/CAM system. The test groups were divided by four groups, single crown, 2-units bridge, 3-units bridge and 4-units bridge and 10 zirconia cores per each group. The results of mean marginal gaps were $42.95{\pm}6.93{\mu}m$ in the single crown, $43.53{\pm}5.27{\mu}m$ in 2-unit, $53.43{\pm}13.38{\mu}m$ in 3-unit, and $50.85{\pm}8.25{\mu}m$ in 4-unit on each. The marginal gap of mesial and distal surfaces were statistically significant differences between single, 2-unit group and 3-unit, 4-unit group (p<.05) and this results was effected by the span length. The buccal and lingual surfaces were no statistically significant differences within all groups(p>.05). From this results the span length of the zirconia core may have influence on marginal fitness and the marginal gaps were within the clinically allowed range.

• Journal of dental hygiene science
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• v.13 no.3
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• pp.290-295
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• 2013

The purpose of this study was to investigate the shear bond strength between various commercial all-ceramic system core and veneering ceramics, and evaluate the clinical stability by comparing the conventional metal ceramic system. The test samples were divided into three groups: Ni-Cr alloy (metal bond), yttria-stabilized, tetragonal zirconia polycrystal (Y-TZP) (zirconia bond), lithium disilicate (lithium disilicate bond). The veneering porcelain recommended by the manufacturer for each type of material was fired to the core. After firing, the specimens were subjected to shear force in a universal testing machine. Load was applied at a crosshead speed of 0.50 mm/min until failure. Average shear strengths (mega pascal) were analyzed with a one-way analysis of variance and the Tukey test (${\alpha}$=0.05). The mean shear bond strength${\pm}$SD in MPa was $44.79{\pm}2.31$ in the Ni-Cr alloy group, $28.32{\pm}4.41$ in the Y-TZP group, $15.91{\pm}1.39$ in the Lithium disilicate group. The ANOVA showed a significant difference among groups (p<0.05). None of the all-ceramic system core and veneering ceramics could attain the high bond strength values of the metal ceramic combination.

• Journal of the Korean Chemical Society
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• v.66 no.2
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• pp.107-123
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• 2022

The purpose of this study is to investigate the effects of learning using computer-based science inquiry program. To this end, the three lessons computer-based science inquiry were developed in domain of material's properties. The developed program was put into K middle school located in Seoul and the effects were verified. For the experimental group, the three lessons computer-based science inquiry related to the separation of mixture were introduced, and for the comparison group, the contents presented in the textbook were introduced as a teacher-centered teaching method. To verify the effects of the program, 2-way ANCOVA was performed on positive experiences about science and science core competency, and 2-way ANOVA was performed on academic achievement. As a result of the study, there were significant differences between the two groups in positive experiernces about science and scientific core competencies and academic achievement (p<.05), and group^*gender interaction effect was only significant in academic achievement (p<.05). From the results of this study, we could see the possibility of using a computer-based science inquiry program as a chemistry teaching method that enables sustainable scientific inquiry.

• Journal of Technologic Dentistry
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• v.34 no.2
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• pp.95-103
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• 2012

Purpose: Fracture strength of all-ceramic 3-unit fixed partial dentures manufactured by CAD/CAM and copy-milling systems were evaluated. Methods: Zirconia cores were made by milling the pre-sintered zirconia block by CAD/CAM or copy milling method followed by subsequent sintering. By building-up the corresponding porcelains on the core, all-ceramic bridges were fabricated, and those were evaluated in comparison with PFM fixed partial denture. Results: During the flexural test of the 3-unit PFM bridge, the porcelain started to chip or break at 507.28(${\pm}62.82$)kgf and the metal framework did not break until the maximum load level of 800kgf which was set in the testing instrument of this study. However, among all-ceramic restoration test groups, Everest(EV) group showed a peeling off or breakage of the porcelain from 365.64(${\pm}64.96$)kgf and the core was broken at 491.77(${\pm}55.62$)kgf. Those values of Zirkonzahn(ZR) were 431.03(${\pm}58.47$)kgf and 602.74(${\pm}48.44$)kgf, respectively. The break strength of the porcelain of PFM(PM) group was significantly higher than that of EV (p<0.05) group and there was no significant difference when comparing to that of ZR (p>0.05). ZR group showed higher break strength than that of EV group however there was no significant difference (p>0.05). The break strength of cores were in the increasing order of EV < ZR < PM (p<0.05). Conclusion: We could find that even though the PM group fractured at much higher value than all-ceramic cores, the breakage values of the porcelain of PM group with crack formation or delamination, which will be regarded as clinical failure, was significantly higher than that of EV group and not significantly higher than that of ZR group at p-values of 0.05. The break strength of ZR group was higher than that of EV group at an insignificant level(p>0.05).

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.26 no.1
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• pp.22-29
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• 2015

Objectives : Repetitive and stereotyped behaviors are core symptoms in children with autism spectrum disorders (ASD). The purpose of our study was to investigate the frequency of motor stereotypes in ASD children and their clinical features. Methods : Among 171 ASD children (age range, 3-15), the ASD group with motor stereotypes was defined according to two items in the Korean version of Autism Diagnostic Interview-Revised (K-ADI-R). We compared the clinical features, behavior problems and severity of other domains in the K-ADI-R and executive functions between the ASD group with motor stereotypes and the ASD group without motor stereotypes. Results : Ninety (52.6%) of 171 ASD children had motor stereotypes. The ASD group with motor stereotypes had a lower intelligence quotient score (62.23 vs. 84.94, p<.001) compared to the ASD group without motor stereotypes. The ASD group with motor stereotypes had more impairments in the social interaction domain [adjusted odds ratio (AOR) 1.11, p=.001] and communication domain (AOR 1.15, p=.008). Thought problems and lethargy were more frequent in the ASD group with motor stereotypes than the ASD group without motor stereotypes (AOR 2.059, p=.034 ; adjusted OR 1.045, p=.046). However, no significant differences in executive function were observed between the ASD group with motor stereotypes and the ASD group without motor stereotypes. Conclusion : The ASD group with motor stereotypes showed more impairment in social interaction and communication domains, which are core symptoms of autism. Motor stereotypes may indicate greater severity of ASD.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.2
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• pp.143-150
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• 2010

Purpose: The purpose of this study is to fabricate the new zirconia block (CNU block) and to evaluate fit of core and porcelain veneered zirconia crown. Material and methods: The experimental blocks were fabricated from the commercial ytrria-stabilized zirconia powder (KZ-3YE Type A). The powder was uniaxial pressing and the green bodies were conducted using the Cold Isostatic Pressing. The zirconia blocks were presintered at $1040^{\circ}C$ and the final sintering was performed at $1450^{\circ}C$. The Kavo Everest ZS $blank{(R)}$ (KaVo, Biberach/ $Ri{\beta}$.) was used as a control group. The linear shrinkage of CNU block and Kavo block were compared. Twenty-one cores for porcelain veneered crowns were fabricated with CAD/CAM system ($Everest{(R)}$, Biberach/ $Ri{\beta}$.). Group I; seven cores fabricated from Kavo blocks, Group II; seven cores fabricated from CNU blocks, Group III; seven cores from CNU blocks and porcelain veneering for crowns. All specimens were cemented and sectioned into two planes; diagonal and bucco-lingual. The measurement of the marginal, internal, and occlusal fit was carried out using SEM ($S-4800^{(R)}$) at $30{\times}$. The results were analyzed by one-way ANOVA test. Results: The linear shrinkage of the CNU block and the KaVo block was 19.00% and 20.09%. The marginal gap of cores ($29.67{\pm}6.58{\mu}m$) fabricated from CNU blocks showed significantly smaller than that of the cores of Kavo blocks ($36.84{\pm}7.18{\mu}m$) (P < .05). The internal gaps of the porcelain veneered crowns ($32.23{\pm}6.33{\mu}m$) were larger than those of the other two groups ($37.57{\pm}6.81{\mu}m$ and $38.14{\pm}6.81{\mu}m$). Conclusion: No statistically significant difference was found in between experimental groups and control group. The experimental groups in marginal gap showed significantly smaller than the control group.

• Journal of Welding and Joining
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• v.32 no.4
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• pp.10-14
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• 2014

Laser aided Direct Metal Tooling(DMT) process is a kind of Additive Manufacturing processes (or 3D-Printing processes), which is developed for using various commercial steel powders such as P20, P21, SUS420, H13, D2 and other non-ferrous metal powders, aluminum alloys, titanium alloys, copper alloys and so on. The DMT process is a versatile process which can be applied to various fields like the mold industry, the medical industry, and the defense industry. Among of them, the application of DMT process to the mold industry is one of the most attractive and practical applications since the conformal cooling channel core of injection molds can be fabricated at the slightly expensive cost by using the hybrid fabrication method of DMT technology compared to the part fabricated with the machining technology. The main objectives of this study are to provide various characteristics of the parts made by DMT process compared to the same parts machined from bulk materials and prove the performance of the injection mold equipped with the conformal cooling channel core which is fabricated by the hybrid method of DMT process.