• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.3
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• pp.47-56
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• 2020

In this study, three levels of W/B(Water to Binder) ratio (0.37, 0.42, 0.47) and substitution ratio of GGBFS (Ground Granulated Blast Furnace Slag) rate (0 %, 30 %, 50 %) were considered to perform RCPT (Rapid Chloride Diffusion Test) at the 1,095 aged day. Accelerated chloride diffusion coefficient and passed charge of each concrete mixture were assessed according to Tang's method and ASTM C 1202, and improving behaviors of durability performance with increasing aged days are analyzed based on the test results of previous aged days from the preceding study. As the age of concrete increases, the passed charge and diffusion coefficient have been significantly reduced, and especially the concrete specimens containing GGBFS showed a significantly more reduction than OPC(Ordinary Portland Cement) concrete specimen by latent hydraulic activity. In the case of OPC concrete's results of passed charge, at the 1,095 days, two of them were still in the "Moderate" class. So, if only OPC is used as the binder of concrete, the resistance performance for chloride attack is weak. In this study, the time-parameters (m) were derived based on the results of the accelerated chloride diffusion coefficient, and the deterministic and probabilistic analysis for service life were performed by assuming the design variable as a probability function. For probabilistic service life analysis, durability failure probabilities were calculated using Monte Carlo Simulation (MCS) to evaluate service life. The service life of probabilistic method were lower than that of deterministic method, since the target value of PDF (Probability of Durability Failure) was set very low at 10 %. If the target value of PDF suitable for the purpose of using structure can be set and proper variability can be considered for each design variable, it is believed that more economical durability design can be made.

• Korean Journal of Heritage: History & Science
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• v.54 no.3
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• pp.150-167
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• 2021

Since the advent of tertiary curriculum, middle school history education has been focused on political history, but many students perceive history as a simple memorization subject and complain about difficulties in abstract learning. The researcher saw this problem as caused by the history curriculum, and carried out this study for the purpose of proposing a revitalization of cultural property education in the middle school history curriculum. First, through the analysis of prior research, the usefulness of cultural property education, such as nurturing creative talent and realizing interactive history classes, was revealed, and the problems of the current political history-centered middle school history curriculum were pointed out. Afterwards, as a result of conducting an opinion survey on middle school 3rd grade students and social studies teachers, it was found that first, both middle school students and their teachers thought that the current political history-centered history had much room for improvement. Second, all groups agreed on the necessity of cultural property education in history education. However, in reality, it was found that it was not easy to sufficiently educate students about cultural property in a political history-centered curriculum. Third, teachers thought that it was necessary to improve the current history curriculum in order to enhance cultural property education. Based on these findings, the researcher suggested an improvement plan for the 2015 revised history curriculum. First, in the 'nature of the subject' section, cultural properties and historical materials should be included, and in the 'objective' section, politics, economy, society, and culture should be included. Contents related to cultural properties should be added to the sub-themes in the 'content system and achievement standards', and cultural properties-related contents should be further reinforced in the achievement standards, 'teaching, learning and evaluation'. It was suggested that this section should include cultural property learning and historical material learning, and guidance on teaching and learning methods of cultural property education should be added. If these aspects are reflected in the 2022 revised curriculum that is currently being developed, cultural property education will be improved, and more lively history education will be provided to students.

• Korean Journal of Heritage: History & Science
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• v.55 no.2
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• pp.168-184
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• 2022

This paper examined the construction techniques of the earthen fortifications in the Hanseong Period of Baekje Kingdom, which has been researched most frequently among the Three Kingdoms. The construction processes of the Earthen Fortifications were reviewed and dividing into 'selection of location and construction of the base', 'construction of the wall', and 'finish, extension and repair'. The results show that various techniques were mobilized for building these earthen fortifications. Techniques which were adequate for the topography were utilized for reinforcing the base, and several other techniques were used for constructing the wall. In particular, techniques for wall construction may be clearly divided into those of the fill(盛土) and panchuk(版築) techniques. The fill method has been assumed since the 2000s to have been more efficient than the panchuk technique. This method never uses the structure of the panchuk technique and is characterized by a complex soil layer line, an alternate fill, use of 'earth mound(土堤)'/'clay clod(土塊)', and junctions of oval fill units. The fill method allows us to understand active technological sharing and application among the embankment structures in the period of the Three Kingdoms. The panchuk technique is used to construct a wall using a stamped earthen structure. This technique is divided into types B1 and B2 according to the height, scale, and extension method of the structure. Type B1 precedes B2, which was introduced in the late Hanseong Period. Staring with the Pungnap Earthen Fortification in Seoul, the panchuk technique seems to have spread throughout South Korea. The techniques of the fill and panchuk techniques coexisted at the time when they appeared, but panchuk earthen fortifications gradually dominated. Both techniques have completely different methods for the soil layers, and they have opposite orders of construction. Accordingly, it is assumed that both have different technical systems. The construction techniques of the earthen fortifications began from the Hanseong Period of Baekje Kingdom and were handed down and developed until the Woongjin-Sabi Periods. In the process, it seems that there existed active interactions with other nations. Recently, since studies of the earthen fortifications have been increasing mainly in the southern areas, it is expected that comparative analysis with neighboring countries will be done intensively.