This study proposes ‘the textbook with multiple editions', which is gradually improved via new editions as a method of managing the quality of the textbook, and the main purpose of this study is to explore the applications of this new type of textbook. Also, systemic support measures are dealt with. After reviewing the preceding studies, overseas cases were investigated, and a survey was conducted to find out which school-level and subject is more suitable for the introduction of the textbook with multiple editions. As a result of the study, first, in the case of school level, it is more appropriate to apply the textbook with multiple editions for elementary and middle school. Second, in the case of subject, Mathematics, Moral Education, and Korean language are top 3 in elementary school, and Chinese characters, History, Mathematics, Moral Education, and Korean language are top 5 in middle school that the need for the multiple editions is high. Third, it was confirmed that it was necessary to revise some contents of the relevant provisions to systematically support the textbook with multiple editions. According to the results, it was suggested that the introduction of the textbook with multiple editions should be carried out on a trial basis among 'Korean language, Mathematics, Moral Education, History, and Atlases' in elementary and middle schools. It was also proposed to improve the relevant provisions.

According to building regulations, fire dampers should be installed in or close to the part of the duct that penetrates the fire compartment. Accordingly, in construction sites, fire dampers are installed in or adjacent to the fire compartment wall and floor. However, they are often installed too far away from the fire compartment wall and floor because the law does not stipulate a clear standard for “close”. If this occurs, the duct and sleeve in the spaced part may be transformed by the high heat of a fire. Through this, smoke and flames can be directly transmitted to the neighboring compartment space, failing to ensure fire safety. Therefore, this study investigated the dependence of fire safety on the spaced installation of fire dampers by performance verification. From the performance verification results, it was found that the separation distance of the fire damper should be minimized (i.e., attached to the wall) to ensure fire safety.

In this study, an attempt was made to conduct a case study on the development of ground expansive displacement due to lack of bearing capacity of original ground in spite of applying reinforcement treatments that intended to enhance the stability of big size high-speed rail tunnel in large fault zone. For the purpose of this, in-situ measurements made in the middle of excavation stage were analyzed in order to characterize ground responses and numerical analysis was performed to evaluate the effectiveness of reinforcement technique such as elephant foot method applied for this site via comparing with field monitoring measurements. In addition, further numerical studies were carried out to investigate the influence of leg pile installation angle and length, which is one of types of elephant foot method. The results revealed that the optimum condition for the leg pile installation is to maintain 45 degree of installation angle along with 6 meter of embedment depth.