• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.1
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• pp.57-70
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• 2009

Considerable advance has been made on research on effect of steel pipe Umbrella Arch Method (UAM) and mechanical reinforcement mechanism through numerical analyses and experiments. Due to long analysis time of three-dimensional analysis and its complexity, un-quantitative two-dimensional analysis is dominantly used in the design and application, where equivalent material properties of UAM reinforced area and ground are used, For this reason, development of reasonable, theoretical, quantitative and easy to use design and analysis method is required. In this study, both field UAM tests and laboratory tests were performed in the residual soil to highly weathered rock; field tests to observe the range of reinforcement, and laboratory tests to investigate the change of material properties between prior to and after UAM reinforcement. It has been observed that the increase in material property of neighboring ground is negligible, and that only stiffness of steel pipe and cement column formed inside the steel pipe and the gap between steel pipe and borehole contributes to ground reinforcement. Based on these results and concept of Convergence Confinement Method (CCM), two dimensional axisymmetric analyses have been performed to obtain the longitudinal displacement profile (LDP) corresponding to arching effect of tunnel face, UAM effect and effect of supports. In addition, modified load distribution method in two dimensional plane-strain analysis has been suggested, in which effect of UAM is transformed to internal pressure and modified load distribution ratios are suggested. Comparison between the modified method and conventional method shows that larger displacement occur in the conventional method than that in the modified method although it may be different depending on ground condition, depth and size of tunnel, types of steel pipe and initial stress state. Consequently, it can be concluded that the effect of UAM as a beam in a longitudinal direction is not considered properly in the conventional method.

• (The) Research of the performance art and culture
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• no.39
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• pp.609-635
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• 2019

This study analyzed five official entries in the 3rd Cheong Kong Festival contest and analyzed the patterns of teen audience empathy. The tools used for this analysis were 'characters, acting, background and theme'. Firstly, characters were mostly teenagers and out-of-school teenagers, but there were other performances that focused on the relationship between teenagers and adults or focused on the youth, which the teen audience preferred. And they preferred realism acting to emotional acting and preferred musical acting to realism acting. In addition, the background of the events covered in the performance was evaluated to be like this: the closer the audience was to the youth, the higher the audience sympathized with the performance, and the closer the subject matter was to the youth's interest, the more positive it received. In summing up the opinions of the youth evaluation team, the first audience-participating Sinpa Theater, "Mr. X" was evaluated to expand the scope of teenagers to 20s and to show the negative and heavy reality as fun and beneficial one. Secondly, when it comes to non-prejudiced youth theatre "The Turtle", which have a high level of empathy, it was evaluated to shape the prejudice about others through the symbol of 'bag'. Thirdly, regarding the time-traveling retro-style youth theatre of the 'a jam-packed Bus', it was evaluated to be a well-made retro-style youth theatre. Regarding the 'Lunar Eclipse', which showed the aesthetic of the relationship, scenes were evaluated to be built with omission and restraint. Regarding "B Officer on and Love Letter", it was evaluated to be adapted to a musical from Hyun Jingun's novel, which was released 100 years ago. Lastly, the performance desired by the youth evaluation team was a performance with a high level of 'sympathy' and 'education'. In other words, they preferred performances that empathize with the emotions and thoughts of teenagers, and on the other hand, they wanted to see performances that allowed them to see the world broadly outside their own worlds. If youth theater is created by referring to the evaluation of youth as it is in this study, the audience will be more sympathetic to performances.

• Korean Journal of Breeding Science
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• v.51 no.4
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• pp.298-317
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• 2019

A statistical analysis of 9,771 non-glutinous rice in breeding line germplasm collected from Korea (2,836), China (2,136), Japan (1,219), and the Philippines (1,213) was conducted using normal distribution, variability index value (VIV), analysis of variation (ANOVA) and Ducan's multiple range test (DMRT) based on the data obtained from NIRS analysis. According to the normal distribution, the average protein content was 7.9%, and non-glutinous rice ranging over 10% amylose had 23.6% average content. Most resources were between 5.3 and 10.5% in protein content, and 15.7 and 31.5% in amylose content. The VIV was 0.54 for protein, and 0.83 for amylose. The average amylose content was 25.18%, 24.54%, 22.08%, and 21.47% in Filipino, Chinese, Korean, and Japanese resources, respectively, wheereas the average protein content was found to be 8.19%, 7.79%, 7.58%, and 7.42% in Filipino, Chinese, Korean, and Japanese resources, respectively. The ANOVA of amylose and protein content showed significant differences at the level of 0.01. The F-test value was 412.2 for amylose content, and 108.4 for protein when compared with the critical value of 3.78. The DMRT of amylose and protein content showed significant differences (p<0.01) among resources from different countries. The Filipino resources had the highest level of amylose and protein content, whereas; the lowest level of amylose and protein content were found in Japanese when compared with resources of other origins. These results are recommended as helpful materials in the field of breeding.

• Journal of Wetlands Research
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• v.25 no.4
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• pp.306-314
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• 2023

Stream sediments are an important component of water quality management because they are receptors of various pollutants such as heavy metals and organic matters emitted from upland sources and can be secondary pollution sources, adversely affecting water environment. To effectively manage the stream sediments, identification of primary sources of sediment contamination and source-associated control strategies will be required. We evaluated the performance of machine learning models in identifying primary sources of sediment contamination based on the physico-chemical properties of stream sediments. A total of 356 stream sediment data sets of 18 quality parameters including 10 heavy metal species(Cd, Cu, Pb, Ni, As, Zn, Cr, Hg, Li, and Al), 3 soil parameters(clay, silt, and sand fractions), and 5 water quality parameters(water content, loss on ignition, total organic carbon, total nitrogen, and total phosphorous) were collected near abandoned metal mines and industrial complexes across the four major river basins in Korea. Two machine learning algorithms, linear discriminant analysis (LDA) and support vector machine (SVM) classifiers were used to classify the sediments into four cases of different combinations of the sampling period and locations (i.e., mine in dry season, mine in wet season, industrial complex in dry season, and　industrial complex in wet season). Both models showed good performance in the classification, with SVM outperformed LDA; the accuracy values of LDA and SVM were 79.5% and 88.1%, respectively. An SVM ensemble model was used for multi-label classification of the multiple contamination sources inlcuding landuses in the upland areas within 1 km radius from the sampling sites. The results showed that the multi-label classifier was comparable performance with sinlgle-label SVM in classifying mines and industrial complexes, but was less accurate in classifying dominant land uses (50~60%). The poor performance of the multi-label SVM is likely due to the overfitting caused by small data sets compared to the complexity of the model. A larger data set might increase the performance of the machine learning models in identifying contamination sources.

• Korean Journal of Remote Sensing
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• v.39 no.6_2
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• pp.1635-1650
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• 2023

Under global warming, the steadily increasing sea surface temperature (SST) severely impacts marine ecosystems,such as the productivity decrease and change in marine species distribution. Recently, the catch of Todarodes Pacificus, one of South Korea's primary marine resources, has dramatically decreased. In this study, we analyze the marine environment that affects the formation of fishing grounds of Todarodes Pacificus and develop seasonal habitat suitability index (HSI) models based on various satellite data including Geostationary Ocean Color Imager (GOCI) data to continuously manage fisheries resources over Korean exclusive economic zone. About 83% of catches are found within the range of SST of 14.11-26.16℃,sea level height of 0.56-0.82 m, chlorophyll-a concentration of 0.31-1.52 mg m^-3, and primary production of 580.96-1574.13 mg C m^-2 day^-1. The seasonal HSI models are developed using the Arithmetic Mean Model, which showed the best performance. Comparing the developed HSI value with the 2019 catch data, it is confirmed that the HSI model is valid because the fishing grounds are formed in different sea regions by season (East Sea in winter and Yellow Sea in summer) and the high HSI (> 0.6) concurrences to areas with the high catch. In addition, we identified the significant increasing trend in SST over study regions, which is highly related to the formation of fishing grounds of Todarodes Pacificus. We can expect the fishing grounds will be changed by accelerating ocean warming in the future. Continuous HSI monitoring is necessary to manage fisheries' spatial and temporal distribution.

• Korean Journal of Remote Sensing
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• v.39 no.5_4
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• pp.1097-1109
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• 2023

Urban is an area where small-scale changes to individual buildings occur frequently. An existing urban building database requires periodic updating to increase its usability. However, there are limitations in data collection for building changes over a wide urban. In this study, we check the possibility of detecting building changes and updating a building database by using satellite images that can capture a wide urban region by a single image. For this purpose, building areas in a satellite image are first extracted by projecting 3D coordinates of building corners available in a building database onto the image. Building areas are then divided into roof and facade areas. By comparing textures of the roof areas projected, building changes such as height change or building removal can be detected. New height values are estimated by adjusting building heights until projected roofs align to actual roofs observed in the image. If the projected image appeared in the image while no building is observed, it corresponds to a demolished building. By checking buildings in the original image whose roofs and facades areas are not projected, new buildings are identified. Based on these results, the building database is updated by the three categories of height update, building deletion, or new building creation. This method was tested with a KOMPSAT-3A image over Incheon Metropolitan City and Incheon building database available in public. Building change detection and building database update was carried out. Updated building corners were then projected to another KOMPSAT-3 image. It was confirmed that building areas projected by updated building information agreed with actual buildings in the image very well. Through this study, the possibility of semi-automatic building change detection and building database update based on single satellite image was confirmed. In the future, follow-up research is needed on technology to enhance computational automation of the proposed method.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.17 no.4
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• pp.31-43
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• 2022

Startups are recognized as the vitality of the economy, and countries are competing to attract competitive overseas entrepreneurs and startups to their own startup ecosystem. In this global trend, entrepreneurs cross the border without hesitation, expecting abundant available resources and a startup friendly environment. Despite the increasing frequency of start-up migration between countries, studies related to this are very rare. Therefore, this study has chosen the cross-border migration of startups between countries as a research topic, and those who have been involved in the cross-border entrepreneurial migration to South Korea as a research sample. This study consists of two stages. The first research stage hires a Delphi method to collect expert opinions and find major factors related to the global startup migration. Drawing on the prior literature on the regional startup ecosystem at the national level, this stage is to conduct expert interviews in order to discover underlying factors and subfactors important for global migration of startups. The second stage measures the importance of the factors and subfactors using the AHP model. The priorities of factors and factors were identified hiring the overseas entrepreneurs who moved to Korea as the AHP survey samples. The results of this study suggest some interesting implications. First, a group of entrepreneurs with nomadic tendencies was found in the trend of global migration of entrepreneurs. They had already started their own businesses with the same business ideas in multiple countries before settling down in Korea. Second, important unique factors and subfactors in the context of global start-up migration were identified. A good example is the government's support package, including start-up visas. Third, it was possible to know the priority of the factors and subfactors that influence the global migration of startups This study is meaningful in that it preemptively conducted exploratory research focusing on a relatively new phenomenon of global startup migration, which recently catches attention in the global startup ecosystem. At the same time, it has a limitation in that it is difficult to generalize the meanings found in this study because the research was conducted based on the case of South Korea

• Korean Journal of Ichthyology
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• v.35 no.4
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• pp.354-360
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• 2023

The diet composition of Tanaka's snailfish, Liparis tanakae were collected by bottom trawl net in the Yellow Sea of Korea during 2022 (April, August, October, and November). The size of the specimens ranged from 3.8 to 52.2 cm in total length. L. tanakae were primary consumed caridea shrimps (Crangon hakodatei, Eualus spathulirostris, etc.) and specialist feeder mainly consumed caridea shirmps (C. hakodatei). The L. tanakae's trophic level is 3.63. Caridea shrimps were the primary prey items for all size groups (<20 cm, 20~30 cm, 30~40 cm, ≥40 cm). The proportion of E. spathulirostris has increased as the body size of L. tanakae increased, whereas the proportion of C. hakodatei decreased gradually. As the body size of L. tanakae increased the mean weight of prey per stomach (mW/ST) tended to increase significantly (One-way ANOVA, P<0.05). The caridea shrimps were the primary prey items throught all seasons. In summer, the main prey items were the C. hakodatei, however, in autumn, the proportion of C. hakodatei decreased while the proportion of E. spathulirostris increased.

• Journal of The Korean Association For Science Education
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• v.29 no.8
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• pp.923-933
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• 2009

In this study, analysis was carried out on science experiment in high school textbooks, illustrating 'the effect of pH on enzyme activity.' Five of the total 16 science textbooks introduced in this experiment, and the experimental conditions therein were analyzed. Textbook analysis revealed that pH of below 3 was used for 'acidic condition' and that of over 11 was used for 'basic' condition. Using the experimental conditions described in the textbooks, review experiments were performed. Buffering effect with the addition of saliva was found in the pH region around 7 when buffer solution was not used to control pH as was in the textbooks. The enzyme activity experiments were performed controlling pH from pH 2 to 13 with buffer. The color of the sample was blue from pH 2 to 4, and then disappeared from pH 5 to 8, reflecting that starch was digested owing to enzyme activity. In pH 9 light blue color appeared, indicating de-activation of enzyme under this basic condition. However, the blue color of the sample became lighter at pH 10 and disappeared from pH 11, which was different from the expected behavior anticipating dark blue color due to de-activation of enzyme under strong basic condition. These results can wrongly influence students to interpret that enzyme can be activated in this pH condition. So, we analyzed the reason for the color of the sample turning light blue in pH 10 and disappeared from pH 11. The analysis resulted that ${I_3}^-$ and/or ${I_5}^-$ subunits of polyiodides within the starch helix in starch-iodine complex, showing blue, decreases above pH 10 due to disproportionation to HOI, ${IO_3}^-$, and $I^-$ by the reaction with $OH^-$.

• Journal of the Korean Society of Radiology
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• v.18 no.1
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• pp.45-52
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• 2024

In this study, an AI-based algorithm was developed to prevent image quality deterioration and reading errors due to patient movement in PET/CT examinations that use radioisotopes in medical institutions to test cancer and other diseases. Using the Mothion Free software developed using, we checked the degree of correction of movement due to breathing, evaluated its usefulness, and conducted a study for clinical application. The experimental method was to use an RPM Phantom to inject the radioisotope 18F-FDG into a vacuum vial and a sphere of a NEMA IEC body Phantom of different sizes, and to produce images by directing the movement of the radioisotope into a moving lesion during respiration. The vacuum vial had different degrees of movement at different positions, and the spheres of the NEMA IEC body Phantom of different sizes produced different sizes of lesions. Through the acquired images, the lesion volume, maximum SUV, and average SUV were each measured to quantitatively evaluate the degree of motion correction by Motion Free. The average SUV of vacuum vial A, with a large degree of movement, was reduced by 23.36 %, and the error rate of vacuum vial B, with a small degree of movement, was reduced by 29.3 %. The average SUV error rate at the sphere 37mm and 22mm of the NEMA IEC body Phantom was reduced by 29.3 % and 26.51 %, respectively. The average error rate of the four measurements from which the error rate was calculated decreased by 30.03 %, indicating a more accurate average SUV value. In this study, only two-dimensional movements could be produced, so in order to obtain more accurate data, a Phantom that can embody the actual breathing movement of the human body was used, and if the diversity of the range of movement was configured, a more accurate evaluation of usability could be made.