• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.2
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• pp.279-299
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• 2019

Recently occurred earthquake Gyeongju and Pohang served as a momentum to remind that Korean peninsular is not a safety zone from earthquake anymore. The importance of seismic design, therefore, have been realized and researches regarding design response spectrum have been actively carried out by many researchers and engineers. Current tunnel seismic design method is conducted to check safety of tunnel structure by dynamic numerical analysis with condition of completed lining installation, so, it is impossible to consider safety of tunnel behavior under construction. In this study, therefore, dynamic numerical analysis considering seismic wave propagations has been performed after back analysis using results from field monitoring of tunnel under construction in fractured zone and 1st reinforcement (shotcrete, rockbolt) behaviour are analyzed. Waves are classified by period characteristic (short and long). As a result, the difference depending on period characteristic is minor, and increasements of displacement are obtained at crown displacement due to seismic wave is 28~31%, 14~16% at left side of tunnel in the fractured zone, 13~27% at right side of tunnel in the bed rock, respectively. In case of shotcrete axial force is increased 113~115% at tunnel crown, 102% at left side, 106~110% at right side, respectively. Displacement and axial force of rockbolts which are selected by type of anchored grounds (only fractured zone, fractured zone and bed rock, only bedrock) are analyzed, as a result, rockbolt which is anchored to fractured zone and bed rock at the same time are weaker than any other case.

• Journal of the Korean GEO-environmental Society
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• v.22 no.10
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• pp.21-29
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• 2021

Most concrete gravity-type dams in and out of the country were constructed by column method to control cracks caused by concrete hydration heat generated during construction, resulting in a certain level of leakage after impoundment through various causes, such as contraction joints and construction joints. However, due to the characteristics of concrete structures that shrink and expand according to temperature, concrete dams have vertical joints and drains to allow penetration. PVC waterproof shows excellent effects in completion of the dam, which however increases the possibility of interfacial failure due to different thermal expansion. Other causes of penetration may include problems with quality control during installation, generation of cracks due to heat of hydration of concrete, waterproofing methods, etc. In the case of Bohyunsan Dam in Yeongcheon, North Gyeongsang Province, the amount of drainage in the gallery was checked and underwater, and it was confirmed that there are many penetrations from drainage holes connected to vertical joints, and that some of the PVC waterproofs are not fully operated. As a new method to prevent penetration through vertical joints, D.S.I.M. (Dam Sealing Innovation Method) developed by World E&C was applied to Bohyunsan Dam and checked the amount of drainage in the gallery. As a result of first testing three most leaking vertical joints, the drain in the gallery was reduced by 87% on the average and then applied to the remaining 13 locations, which showed a 83% reduction effect based on the total drain in the gallery. Summing up these results, it was found that D.S.I.M. preventing water leakage from the upstream face is a valid construction method to reduce the water see-through and penetration quantity seen in downstream faces of concrete dams. If D.S.I.M. is applied to other concrete dams at domestic and abroad, it is expected that it will be very effective to prevent water leakage through vertical joints that are visible from downstream faces.

• KIPS Transactions on Software and Data Engineering
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• v.10 no.7
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• pp.271-278
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• 2021

As the current cyber attacks become more intelligent, the existing Intrusion Detection System is difficult for detecting intelligent attacks that deviate from the existing stored patterns. In an attempt to solve this, a model of a deep learning-based intrusion detection system that analyzes the pattern of intelligent attacks through data learning has emerged. Intrusion detection systems are divided into host-based and network-based depending on the installation location. Unlike network-based intrusion detection systems, host-based intrusion detection systems have the disadvantage of having to observe the inside and outside of the system as a whole. However, it has the advantage of being able to detect intrusions that cannot be detected by a network-based intrusion detection system. Therefore, in this study, we conducted a study on a host-based intrusion detection system. In order to evaluate and improve the performance of the host-based intrusion detection system model, we used the host-based Leipzig Intrusion Detection-Data Set (LID-DS) published in 2018. In the performance evaluation of the model using that data set, in order to confirm the similarity of each data and reconstructed to identify whether it is normal data or abnormal data, 1D vector data is converted to 3D image data. Also, the deep learning model has the drawback of having to re-learn every time a new cyber attack method is seen. In other words, it is not efficient because it takes a long time to learn a large amount of data. To solve this problem, this paper proposes the Siamese Convolutional Neural Network (Siamese-CNN) to use the Few-Shot Learning method that shows excellent performance by learning the little amount of data. Siamese-CNN determines whether the attacks are of the same type by the similarity score of each sample of cyber attacks converted into images. The accuracy was calculated using Few-Shot Learning technique, and the performance of Vanilla Convolutional Neural Network (Vanilla-CNN) and Siamese-CNN was compared to confirm the performance of Siamese-CNN. As a result of measuring Accuracy, Precision, Recall and F1-Score index, it was confirmed that the recall of the Siamese-CNN model proposed in this study was increased by about 6% from the Vanilla-CNN model.

• Journal of The Korean Association For Science Education
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• v.44 no.2
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• pp.167-178
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• 2024

In this study, we investigated the perceptions of science-related careers and career education among middle school science teachers. Sixty-four science teachers experienced in teaching unit 7 in the first year of middle school participated. The results of the study revealed that not only careers in science but also careers with science were found to be quite high when teachers were asked to provide examples of science-related careers. Jobs related to research/engineering, which are careers in science, comprised the highest proportion of teachers' answers, followed by jobs related to education/law/social welfare/police/firefighting/military, and health/medical, which are careers with science. However, the proportion of jobs mentioned related to installation/maintenance/production was extremely low. The skills required for science-related careers were mainly perceived to consist of tools for working and ways of working. The number of skills classified under living in the world was perceived to be extremely low across most careers, irrespective of career type. Most teachers only taught unit 7 for two to four sessions and devoted little time to science-related career education, even in general science classes. In the free semester system, a significant number of teachers responded that they provide science-related career education for more than 8 hours. Teachers mainly utilize lecture, discussion/debate, and self-study activities. Meanwhile, in the free semester system, the resource-based learning method was utilized at a high proportion compared to other class situations. Teachers generally made much use of media materials, with the use of textbooks and teacher guides found to be lower than expected. There were also cases of using materials supported by science museums or the Ministry of Education. Teachers preferred to implementing student-centered classes and utilizing various teaching and learning methods. Based on the above research results, discussions were proposed to improve teachers' perceptions of science-related careers and career education.

• Korea Science and Art Forum
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• v.37 no.2
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• pp.219-230
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• 2019

According to the National Statistical Office, the number of senior citizens aged 65 or over has exceeded 7 million as of 2017, and the number of senior citizens who live alone among them exceeded 1.3 million. Most of the senior citizens who live alone suffer from absolute poverty (68.5% of them has monthly income less than 500,000 won) and they have difficulties for basic living in the blind spot of our society. In particular, the heating is quite a serious issue for the senior citizens who live alone and belong to vulnerable social group in the winter, and to make it worse, they are exposed to frequent fire accidents due to the negligence in handling electric appliances such as electric heaters and electric pads. The main reason the indoor tent products are being used by senior citizens who live alone is that it saves energy, ensures warm sleep, and improves fire safety. Following the expansion of the indoor tent market, this study focused on the idea that there is a need for an in door tent suitable for senior citizens who live alone and belong to low income bracket and intended to improve its efficiency in relation to use, resting, and storage. For this, a basic survey was conducted on the products of existing brands to analyze advantages and disadvantages and it was possible to understand the demands that consumers have for existing products. Accordingly, a survey on consumer preference was conducted using a designed model and the Zabara typp, which demonstrated the best efficiency in terms of installation convenience, space usability, and appearance design was selected. Based on the results of selection, the product design and final prototype were completed. The results and details of the study are as follows; First, factors that were not recognized in product development phase could be identified through usability survey and interview with actual users. Second, for the effective aspect of the prototype, senior citizens could install and fold the tend more easily and quickly than expected. Based on these results of this study, it is expected that not only senior citizens who live alone but also various other users can use the tent to create another comfortable private space indoors.

• Asian Journal of Turfgrass Science
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• v.17 no.4
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• pp.155-163
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• 2003

This study was conducted to find out suitable rootzone profile, irrigation system, and turfgrass species for roof turf garden. Treatments of profile with soil amendment were Mixture I: Perlite(PL)60％＋Vermiculite(VC)20％＋Peatmoss(PM)20％, Mixture II: PL60％＋VC 10％＋PM20％＋Sand(SD)10％, Mixture III: PL60％＋VC20％＋PM20％ and Mixture IV: PL60％＋VC10％＋PM20％＋SD10％＋Styrofoam 5cm as a drain layer. To test trickle irrigation for roof garden, intervals of main pipe spacing(50cm, 100cm) and drop hole distance(15, 20, 30, 50 and 100cm)were treated, To select most suitable turfgrass species or mixture, Bermudagrass 'Konwoo', Zoysiagrass 'Konhee' and cool-season grass(Kentucky Bluegrass 80％ ＋ Perennial Ryegrass 20％, Tall Fescue 30％ ＋ KB50％ ＋ PR 20％)were tested. In particle size analysis, the soil amendments Perlite and vermiculite showed very even distribution, however, peatmoss contained mostly coarse particles with fiber over $\Phi$ 4.75mm. Under field moisture condition, vermiculite and peatmoss showed 350％ water holding capacity, on the other hand, sand or Perlite showed 115％ and 166％, respectively. Total weight of soil profile was 139.2kg/$m^2$ with Styrofoam drain layer without sand, which showed most lightest among treatments. Turf quality also resulted positve with Styrofoam drain layer installation. On trickle irrigation system, the proper interval of main drain pipe spacing and drop hole distance were 50cm and 50cm, respectively, In irrigation frequency, once per a day for 15 minute irrigation with 2 1/hr showed the best results on turf quality. Among turfgrass species or cool season grass mixture, warm season turfgrass fine leaf type zoysiagrass 'Konhee' and Bermudagrass 'Konwoo' showed very acceptable result on all over the treatments of rootzone and irrigation system. To apply cool season grasses for the roof garden, advanced researches may be needed to establish the proper soil amendment, rootzone profile, and irrigation system, Application of Bermudagrass 'Konwoo' for roof turf garden also needs successive tests to overcome winter injuries.