• Journal of Korean Tunnelling and Underground Space Association
• /
• v.24 no.6
• /
• pp.637-658
• /
• 2022

TBM tunnel is simple with the iterative process of excavating the ground, building a segment ring-build, and backfilling. Drill & Blast, a conventional tunnel construction method, is more complicated than the TBM tunnel and has some restrictions because it repeats the inspection, drilling, charging, blasting, ventilation, muck treatment, and installation of support materials. However, the preparation work for excavation requires time and cost based on a very detailed plan compared to Drill & Blasting, which reinforces the ground and forms a tunnel after the formation of tunnel portal. This is because the TBM equipment for excavating the target ground determines the success or failure of the construction. If the TBM, an expensive order-made equipment, is incorrectly configured at the assembly stage, it becomes difficult to excavate from the initial stage as well as the main excavation stage. When the assembled shield TBM equipment is dismantled again, and a situation of re-assembly occurs, it is difficult throughout the construction period due to economic loss as well as time. Therefore, in this study, the layout and plan of the site and the assembly process for each major part of the TBM equipment were reviewed for the assembly of slurry shield TBM to construct the largest diameter road tunnel in domestic passing through the Han River and minimized interference with other processes and the efficiency of cutter head assembly and transport were analyzed and improved to suit the site conditions.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.27 no.5
• /
• pp.605-617
• /
• 2021

The recovery of the sedimentary environment around a fallowing shellfish farm during its rest period after 20 years of long-running operation, was explored in Tongyeong Bay of Korea. Seasonal survey on macrobenthos community was conducted from July 2016 to September 2018 at five stations, which included the fallowing shellfish farm after 20-year operation (FF), a newly installed shellfish farm (NF), a shellfish farm for comparison around the closed shellfish farm (CF), and control stations with no farming activities (Con1, Con2). The total number of species and the density of macrobenthos were higher at the shellfish farm stations than the non-shellfish farm station, and their seasonal changes were significant. The dominant species at the shellfish farm stations was Capitella capitata while Paraprionospio patiens was dominant at the non-shellfish farm stations. The two dominant species were potential organic contamination indicators usually inhabiting the areas with dense organic matter. This suggests that the overall survey area was highly polluted with organic matters. Multivariate analysis showed that the macrobenthic community of CF changed to a level similar to that of Con1 immediately after the investigation, but not to a state above the Con1 level. Furthermore, the changes in NF were not significant when compared to those in CF.

• Journal of The Korean Association For Science Education
• /
• v.41 no.4
• /
• pp.325-338
• /
• 2021

In this study, we developed a 15-week educational program for TPACK(Technological Pedagogical Content Knowledge) development of 40 pre-service teachers in a university for teacher training. We also developed a TPACK evaluation framework to evaluate the practical competency of TPACK of pre-service teachers. The developed evaluation framework consisted of 5 levels, from 0 to 4, TPK(Technological Pedagogical Knowledge), TCK(Technological Content Knowledge), and TPACK, respectively. As a result of the evlauation, the levels of TPK, TCK, and TPACK development stages of most pre-service teachers were consistent, but some pre-service teachers' TPK and TCK did not match. It was found that the TPACK stages follow the lower level between TPK and TCK. In addition, as a result of an investigation into the hindrance factors of the TPACK development of pre-service teachers with low TPACK stages in the use of technology, they have distrust of students' ability to learn with self-regulation, distrust of students' ability to interact, and recognition of practical limitations in the school field. Based on these findings, we argued that it was necessary to provide an educational program to help pre-service teachers develop balanced TPK and TCK and eliminate the hindrance factors of the TPACK development of pre-service teachers about technology-using classes.

• Korean Journal of Remote Sensing
• /
• v.37 no.6_1
• /
• pp.1731-1738
• /
• 2021

The objective of this study was to extract individual trees and tree heights using UAV drone images. The study site was Gongju national university experiment forest, located in Yesan-gun, Chungcheongnam-do. The thinning intensity study sites consisted of 40% thinning, 20% thinning, 10% thinning and control. The image was filmed by using the "Mavic Pro 2" model of DJI company, and the altitude of the photo shoot was set at 80% of the overlay between 180m pictures. In order to prevent image distortion, a ground reference point was installed and the end lap and side lap were set to 80%. Tree heights were extracted using Digital Surface Model (DSM) and Digital Terrain Model (DTM), and individual trees were split and extracted using object-based analysis. As a result of individual tree extraction, thinning 40% stands showed the highest extraction rate of 109.1%, while thinning 20% showed 87.1%, thinning 10% showed 63.5%, and control sites showed 56.0% of accuracy. As a result of tree height extraction, thinning 40% showed 1.43m error compared with field survey data, while thinning 20% showed 1.73 m, thinning 10% showed 1.88 m, and control sites showed the largest error of 2.22 m.

• Applied Chemistry for Engineering
• /
• v.32 no.5
• /
• pp.524-531
• /
• 2021

Depending on the type and amount of acid used as a modulator in the manufacturing process, the structural properties of UiO-66 can be modified and the adsorbability of chemical warfare agents can be enhanced. In this study, several acids as a modulator were used to synthesize UiO-66. Their properties were analyzed with FT-IR, XRD, titrator, and adsorption isotherms using chemical warfare agent simulant, DIMP. The UiO-66, structurally damaged by hydrochloric acid as a modulator, showed lower crystallinity and DIMP adsorption capacity and also smaller specific surface area and volume of voids compared to those of UiO-66, which was manufactured using acetic acid, and formic acid as a modulator. Additionally, UiO-66 which was synthesized by adding formic acid and hydrochloric acid as a modulator, showed the highest DIMP adsorption capacity and is likely to be used as an adsorbent for chemical warfare agent in the future.

• Korean Journal of Remote Sensing
• /
• v.37 no.6_1
• /
• pp.1719-1729
• /
• 2021

Leaf area index (LAI) provides valuable information necessary for sustainable and effective management of forests. Although global high resolution LAI data are provided by European Space Agency using Sentinel-2 satellite images, they have not considered forest characteristics in model development and have not been evaluated for various forest ecosystems in South Korea. In this study, we proposed a LAI estimation model combining machine learning and the PROSAIL radiative transfer model using Sentinel-2 satellite data over a local forest area in South Korea. LAI-2200C was used to measure in situ LAI data. The proposed LAI estimation model was compared to the existing Sentinel-2 LAI product. The results showed that the proposed model outperformed the existing Sentinel-2 LAI product, yielding a difference of bias ~ 0.97 and a difference of root-mean-square-error ~ 0.81 on average, respectively, which improved the underestimation of the existing product. The proposed LAI estimation model provided promising results, implying its use for effective LAI estimation over forests in South Korea.

• Journal of Convergence for Information Technology
• /
• v.11 no.9
• /
• pp.145-156
• /
• 2021

This study is aimed to improve the youth theft prevention program with rationality and practicality, based on the needs of practitioners who conduct these programs in fields. The survey questionnaire was prepared based on previous researches, and the survey was conducted on 72 probation officers and education instructors nationwide running a youth theft prevention program. As a result, practitioners reported the lack of self-control and high impulsivity as the main characteristics of the theft delinquent adolescents. And they recognized peer alignment and family problems as the causes of theft. As for the contents of the program, they reported that recidivism prevention skills such as understanding psychological problems, peer relationships, raising a sense of law compliance, anger, impulse control, dealing with negative emotions, and finding alternative behaviors, as well as moral development, are necessary. These results indicate that multi-dimensional interventions such as individuals, families, and peers are needed to prevent recidivism of juvenile theft. Implications of these results, future research directions, and limitations and significance of the study were discussed.

• Journal of the Korea Society of Computer and Information
• /
• v.26 no.10
• /
• pp.83-91
• /
• 2021

In this paper, presents an efficient education method for training specialized edutainment SW education instructors and drone realistic media creators, not just training to acquire certificates through drone manipulation training. To this end, the NCS-based curriculum was derived. The developed curriculum includes the edutainment drone curriculum and the realistic media creator curriculum. Among them, core responsibilities were defined for the drone control curriculum and core tasks, knowledge, and attitudes were described for each. After that, a detailed curriculum for drone control was derived. In the realistic media creator curriculum, pilot education was conducted to actually produce advertisement videos to foster experts who can work directly in the industrial field. Finally, through holding an online conference in a metaverse environment, a virtual conference was operated to share and discuss media videos produced by trainees. After the end of education, the efficiency of this curriculum was proved through education satisfaction analysis for 46 education graduates. This paper presented a method to achieve internalization of SW education in non-face-to-face online education that our society must solve after post-COVID-19. In addition, an efficient educational method in a realistic media environment was suggested by showing a realistic media creator training curriculum, pilot programs, and metaverse conference management cases.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.23 no.5
• /
• pp.325-337
• /
• 2021

On the road and rail tunnels, the evacuation pathway and facilities such as smoke-control and fire suppression system are essential in tunnel fire. In the long twin tunnels, the cross-connection tunnel is usually designed to evacuate from the tunnel where the fire broke out to the other tunnel. In twin shield tunnels, the segment lining has to be demolished to construct the cross-connection tunnel. Considering the modern shield TBM is mostly the closed chamber type, the exposure of underground soil induced by removal of steel segment lining is the most danger construction step in the shield tunnel construction. This case study introduces the excavation method using the thrust of large steel pipe and reviews the measured data after the construction. The large steel pipe thrust method for the cross-connection tunnel can stabilize the excavated face with the two mechanisms. Firstly, the soil in front of excavated face is cylindrically pre-supported by the large steel pipe. Secondly, the excavated face is supported by the plugging effect caused by the soil pressed into the steel pipe. It was reviewed that the large steel pipe thrust method in the cross-connection tunnel is enough to secure the construct ability and stability in soil from the measurement results about the deformation and stress of steel pipe.

• Journal of Korean Library and Information Science Society
• /
• v.52 no.3
• /
• pp.73-99
• /
• 2021

The purpose of this study is to investigate the effects of podcast-produced reading activity programs on reading attitudes and communication skills of high-grade elementary school students. To that end, 20 fifth and sixth graders applied for a reading culture program conducted at N Public Library located in Seoul, Korea, were assigned as experimental and control groups. The total research period is from 8 October 2018 to 11 February 2019. and the class was conducted once a week for 90 minutes, six times for each group, and a total of 12 sessions. The results of this study can be summarized as follows; First, it was found that the reading activity program produced by podcast had a positive effect in all four areas: value domain, motivation·interest domain, habit·attitude, and expectation domain in the reading attitude of high-grade in elementary school. Second, communication skills were found to have a positive effect in all seven sub-areas, such as information collection and listening, overcoming stereotyped thinking, creative communication, self-disclosure, leading communication, and understanding of others' perspectives. In conclusion, the podcast-produced reading activity program had a positive effect on the reading attitude, communication ability, and media ability of high-grade in elementary school, suggesting that it is effective in applying various educational fields.