• International Journal of Highway Engineering
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• v.7 no.4 s.26
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• pp.49-56
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• 2005

The effect of modified asphalts is evaluated by simple comparison of a single parameter (i.e., tensile strength, stiffness, etc.) between modified asphalt mixture and unmodified mixture. The use of a single parameter to evaluate the effect of modified asphalt must be questioned. Rather, a single unified framework that accounts for changes in key mixture properties is needed to effectively evaluate the modified asphalt mixtures. This study used a new performance-based fracture parameter as a single unified framework, the Energy Ratio (ER), for quantifying the effect of modified asphalts oil the fracture resistance of mixtures. The Energy Ratio was then used as a performance criterion for calculating the construction cost of two modified asphalt pavements (SBS and Crumb Rubber) and unmodified asphalt pavement. The results showed that the Energy Ratio of SBS modified asphalt was higher than those of crumb rubber and unmodified asphalt. Cost analyses indicated that the construction cost of the AC layer would be reduced by up to 24% by SBS modification. Based on the results, the Energy Ratio is capable of evaluating the effect of modified mixtures, and may form the basis of a promising fracture criterion for performance-based thickness design in asphalt pavements.

• Journal of the Korean earth science society
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• v.41 no.3
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• pp.261-272
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• 2020

The purpose of this study was to compare the earth science curriculums of South Korea and North Korea. Aspects such as the content of the curriculums and the timing of learning were analyzed, in order to provide basic data that can be used to design a revised and integrated Korean curriculum. The objects of this study were South Korean Science textbooks from grades 5-9, and the high school Unity of Science and Earth Science I and II textbooks. Additionally, from North Korea, the junior middle school Natural Science 1 and 2 textbooks and the senior middle school Chosun Geography 2 and Geography 1 textbooks were analyzed. The results of this study obtained through an analysis that used the Trends in International Mathematics and Science Study (TIMSS 2019) grade 8 earth science assessment framework were as follows. First, South Korea needs to adopt iterative learning. Repetitive learning, which is effective for understanding what is being learned, is applied to only 1 by 8th grade. Second, South Korea needs to adjust the time when certain content is learned. This is because there is a disparity between when content is learned in comparison to North Korea, and the timing of learning of about 50% of the TIMSS standards have not been followed. Third, it is necessary to reflect the content present within the TIMSS that have not been learned. This can be a way to increase the nations' educational competitiveness in the international community. This paper proposed a comparative analysis of South korean and North Korean approaches to the earth science curriculum and conducted practical research to facilitate the construction of an integrated curriculum.

• Journal of Periodontal and Implant Science
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• v.48 no.2
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• pp.103-113
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• 2018

Purpose: The purpose of this retrospective study with 4-12 years of follow-up was to compare the marginal bone loss (MBL) between external-connection (EC) and internal-connection (IC) dental implants in posterior areas without periodontal or peri-implant disease on the adjacent teeth or implants. Additional factors influencing MBL were also evaluated. Methods: This retrospective study was performed using dental records and radiographic data obtained from patients who had undergone dental implant treatment in the posterior area from March 2006 to March 2007. All the implants that were included had follow-up periods of more than 4 years after loading and satisfied the implant success criteria, without any peri-implant or periodontal disease on the adjacent implants or teeth. They were divided into 2 groups: EC and IC. Subgroup comparisons were conducted according to splinting and the use of cement in the restorations. A statistical analysis was performed using the Mann-Whitney U test for comparisons between 2 groups and the Kruskal-Wallis test for comparisons among more than 2 groups. Results: A total of 355 implants in 170 patients (206 EC and 149 IC) fulfilled the inclusion criteria and were analyzed in this study. The mean MBL was 0.47 mm and 0.15 mm in the EC and IC implants, respectively, which was a statistically significant difference (P<0.001). Comparisons according to splinting (MBL of single implants: 0.34 mm, MBL of splinted implants: 0.31 mm, P=0.676) and cement use (MBL of cemented implants: 0.27 mm, MBL of non-cemented implants: 0.35 mm, P=0.178) showed no statistically significant differences in MBL, regardless of the implant connection type. Conclusions: IC implants showed a more favorable bone response regarding MBL in posterior areas without peri-implantitis or periodontal disease.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.4
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• pp.282-289
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• 2020

Purpose: The aim of this in vitro study was to evaluate the accuracy of three different intraoral scanners (IOSs) on digital impressions of different types of endocrown cavity preparations. Materials and methods: Two human mandibular molar teeth were prepared with different endocrown abutment designs: one with a buccal wall (Class 2) and the other without a buccal wall (Class 3). Both cavity designs were scanned using a reference desktop scanner (E3) and three different intraoral scanners: Trios3 (TRI group), Cerec Omnicam (CER group), and i500 (I5 group). The obtained Standard Tessellation Language (.stl) datasets were exported to metrology software. The precision was evaluated based on deviations among repeated scan models recorded by each IOS. The trueness was evaluated based on deviations between the reference data and repeated scans. For detecting interaction, data were statistically analyzed using a univariate analysis of variance (ANOVA) and for analyzing the comparison of the test groups data were analyzed by one-way ANOVA and post-hoc Tukey test at the significance level of .05. Results: The deviation values for both cavity designs in the I5 group were significantly lower than those in the other IOS groups in terms of trueness. For both cavity designs, the TRI group exhibited better precision than the other IOS groups. Conclusion: Different technologies of IOS device's and different endocrown prepration designs affected the accuracy of the digital scans.

• Journal of The Korean Association For Science Education
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• v.25 no.4
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• pp.450-464
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• 2005

The purpose of this study was to design a web-based project learning that is suitable for teaching concepts by studying the motion of the Moon for middle school students and to investigate the effects of the lesson applying designed learning. Designed learning was conducted with 48 ninth graders, who were individually interviewed; 5 males and females students out of the total. The types and factors of the unscientific concepts on the motion of the Moon were analyzed by the pre-test using interviews and questionnaires being evaluated to the degree of concept level that was developed in this study. After the pre-test students were instructed to do the web-based project learning where they could observe the motion of the moon for a month and discuss the results from the observation. After the web-based project learning, the effect of learning was examined by applying the post-test to the students and by analyzing the comparison of the pre-test and the post-test. The web-based project learning was effective for the conceptual change of the motion of the Moon (p<.001). According to the post-test, it positively affected the students and improved their integrated processing skills. Specifically, it had effects on conducting experiments (p<.001), controlling variables and defining operations (p<.05) in integrated processing skills.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.27 no.1
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• pp.5-25
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• 2016

This study attempts to suggest an improvement plan of the currently prescribed record classification standard table as the guidance to select and assess the public records of local governments. For this purpose, this study utilized the methodologies of literature review, survey, and experts' assessments. It investigated the current situation on unit tasks and preservation periods targeting major functions of 'construction and architecture' in the record management standard table in the 9 provinces, and it also deduced the characteristics and problems of unit task and preservation period by comparing and analyzing the unit task and preservation period utilized in more than 3 provinces. Based on the results from the analysis on the current situation and comparison, this study deduced the new unit tasks and preservation periods. And the evaluation targeting practitioners and expertise was conducted, and then the revised design plan was finally presented 4 medium- function items, 18 small - function items operated in more than 4 provinces, 47 unit task items, which led to the total 69 items. This study can be utilized as a guidance for establishing the record management standard table based on the uniqueness and originality of public record of local governments and the task function and organization of institutions in the future.

• Journal of the Korea Concrete Institute
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• v.18 no.5 s.95
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• pp.579-588
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• 2006

In recent years, the availability of high-strength reinforcing and prestressing steels leads us to build economically and efficiently designed concrete structural members. One of critical problems faced to the structural engineers dealing with these types of structural member is controls of crack width that is used as a criterion for the serviceability in the limit state design. Especially, flexural cracking must be controlled to secure the structural safety and to improve the durability as well as serviceability of the load carving members. The proposed method utilizes the results of pure tension test in which tensile loads are applied both side of specimen, done by Ikki. The bond characteristics of deformed reinforcing bar under pure tension is considered by the area of concrete and rib area. The results of proposed method are compared with the test data and the results show that the proposed method can take into account the dimensions, variation of sectional properties, and direction of reinforcing and gives more accurate maximum bond stress and corresponding relative slip than the existing methods. the characteristics of bonding is considered by using dimensionless slip magnitude and effective reinforcement ratio. The validity of the proposed equation is verified by test experimental data.

• Journal of the Korea Convergence Society
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• v.6 no.6
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• pp.221-229
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• 2015

This study aims to identify and analyze the main factors that determine the properties and buying behavior in the premium bottled select and analyze the degree of impact on the relevant variables are premium water demand. When applied to the truncated negative binomial model to derive the study results: The results of estimating the variables that affect the demand for premium mineral water are as follows. Premium bottled water demand of this group my purchases with a choice between buying behavior variables are significantly higher than the relative population. To also do a good ingredient water, it appeared to be on a statistically significant positive effect on the demand for the more groups you purchase a premium bottled water for the purpose of receiving special feeling, just buy purpose is called to drinking water does not significantly affect to be analyzed. Among demographic characteristics it showed that demand for premium bottled water purchases are significantly higher in women than in men, professional / clerical job, such as the military, college graduates were more consumer research as significant in comparison to the relative population. Taste and package design factors of premium bottled mineral water among the select attribute factors are having a significant positive impact on the purchasing demand, local conditions and cost factors have been estimated to be insignificant.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.285-288
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• 2008

A model for the effective moment of inertia $I_{\epsilon}$ as expressed in Branson's equation, in which reduction of the flexural rigidity of RC beams due to cracking are aptly taken into accoun,t is presented. However, KCI Code isn`t considered tension stiffening as it is in debonding of reinforcing bar. Therefore, this equation need to set up suitable to our design Code. The experimental work consisted of casting and testing a total of 6 simply supported reinforced concrete beams and a total of 4 continuos reinforced concrete beams under two point concentrated loads. Main parameters are concrete strength, coverage, bond between concrete and reinforcing bars, are known as have an effect on deflection and tension stiffening. Every test beams had the same $250{\times}350$mm rectangular section, with a simply supported clear span of 4,400 mm and a continuos clear span of 6,500 mm. Comparison of the test results with values obtained using the KCI Code equation of the effective moment of inertia showed a noticeable difference.

• Journal of Technologic Dentistry
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• v.36 no.3
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• pp.141-147
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• 2014

Purpose: Dental casting #Gr I (Co-25Cr-5Mo-3Sn-1Mn-1Si), #Gr II (Co-25Cr-5Mo-5Cu-1Mn -1Si) and #Gr III (Co-25Cr-5Mo-3Sn-5Cu-1Mn-1Si) master alloys of granule type were manufactured the same as manufacturing processes for dental casting Ni-Cr and Co-Cr-Mo based alloys of ingot type. These alloys were analyzed melting processes with heating time of high frequency induction centrifugal casting machine using infrared thermal image analyzer. Methods: These alloys were manufactured such as; alloy design, the first master alloy manufatured using vacuum arc casting machine, melting metal setting in crucible, melting in VIM, pouring in the mold of bar type, cutting the gate and runner bar and polishing. These alloys were put about 30g/charge in the ceramic crucible of high frequency induction centrifugal casting machine and heat, Infrared thermal image analyzer indicated alloys in the crucible were set and operated. Results: The melting temperatures of these alloys measuring infrared thermal image analyzer were decreased in comparison with remanium$^{(R)}$ GM 800+, vera PDI$^{TM}$, Biosil$^{(R)}$ f, WISIL$^{(R)}$ M type V, Ticonium 2000 alloys of ingot type and vera PDS$^{TM}$(Aabadent, USA), Regalloy alloys of shot type. Conclusion: Co-Cr-Mo based alloy in addition to Sn(#Gr I alloy) were decreased the melting temperature with heating time of high frequency induction centrifugal casting machine using infrared thermal image analyzer.