• Journal of the Korea Concrete Institute
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• v.21 no.1
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• pp.29-35
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• 2009

Recently, the press and institute recognized fly ash as it had excellent performance. Its research and applications are on the rise largely as a substitute for cement. On the contrary, it is in a situation that the regulation of high fineness fly ash remains at a low level. As for the fly ash in $3,000{\sim}4,500\;cm^2/g$ class fineness regulated in KS L 5405, it is used by substituting it around the unit weight of cement 20%. Accordingly, the regulation in upper classification is in a situation of being insufficient. Therefore, this study aimed to establish 4000, 6000, and 8000 class of fineness of fly ash and three levels of substitute like 15%, 30%, and 45% in order to analyze the substitute and effect of water-binder ratio for fly ash that affected the properties of ternary system concrete. As a result of experiment by planning water-binder ratio for two levels like 40% and 50%, the more replacement ratio and fineness of fly ash increased in the performance not hardened, the more the fluidity increased. This study has found out that the air content decreased, and that there was setting acceleration and it decreased the heat of hydration. In addition, as for the strength properties in a state of performance hardened concrete, the more the replacement ratio and the ratio of water-binding materials increased, the more it had a tendency of being decreased.

• Journal of the Korea Concrete Institute
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• v.17 no.3 s.87
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• pp.455-464
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• 2005

Today the application of antiwashout underwater concrete to the construction sites is increasing steadily, while its reliability is in issue. Particularly, antiwashout underwater concrete is known to have very weak durability on frost attack, and hence Japan society of civil engineers(JSCE) regulated that not to use of antiwashout underwater concrete where the freezing and thawing is suspected. This study aims the improvement of the freezing and thawing resistance for antiwashout underwater concrete. From the results of fundamental test, FA20 and SG50 showed good performance in fluidity and long term compressive strength than control concrete. Meanwhile, MK10 marked the highest compressive strength through the whole curing age but a defect on fluidity was discovered. The results from the repeated freezing and thawing test show that the large volumes of air entrapped by cellulose based antiwashout underwater admixture gave bad effects to frost durability and hence not much benefits were confirmed from the use of mineral admixtures. However there were some increasing effects on frost durability of MK10 and SG50 by securing $6{\pm}0.5\%$ of entraining air. In the meantime, there was a increasing tendency of frost durability by increasing blame's fineness of ground granulated blast furnace slag.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.573-578
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• 2019

This paper applied to the Korean Lesson using PBL(Problem-Based Learning) based on Google Classroom for Mongolians. Recently, Mongolians trying to learn Korean because of Korean wave. This study aims to develop the online problem-based learning model as a way to develop the creative problem-solving ability of Mongolians who want to learn Korean. We applied 3 problems for 9 weeks. This study shows that the participants experienced the effectiveness of Google Classroom and PBL in many ways, 93% of the participants reported that Google Classroom and PBL helped them to learn Korean easily and interesting distance learning model, 90% of the participants prefer to explore Googlish programs and online learning, 85% of them said that increased interaction others in online environment easily. 100% of them said that thankful for learning Korean with Online tutor anytime on Google Classroom. Truly, 86% of them said PBL was hard to generate and understand it because very new instruction for them and working with team in online learning environment. The study showed that members of Korean Lesson experienced various effects such as understanding of learning contents, understanding of cooperative learning, practical experience, creative problem solving ability, presentation skill, communication ability, self - directed learning ability, self - confidence through Google Classroom based PBL.

• The Korean Journal of Archival Studies
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• no.62
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• pp.225-258
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• 2019

Since the opening of Joseon in 1876, the photographic records of the late Joseon Dynasty and the period of the Korean Empire exist more than expected, considering the technological level and the social situations at that time. Photographs related to Korea can be distributed in various forms, such as illustrations of books printed to introduce Korea to Western society, plates of graphic journalism like newspapers or magazines, vintage prints, photo-postcards, stereo-photographs, card-type photographs, and lantern slides. There are still a great deal left in various archives of the Europe, America, Japan and Korea. According to related researchers, Korean-related photographs taken between 1863 and 1910, since Koreans were first photographed, were at least 3,000 to 4,000 cuts and the photo postcards issued was 25,000. It is said that most of them exist. This paper categorizes two ways of producing and distributing photographic records related to Korea, which were early modern times. The subjects of the photographs are clearly Korea or Koreans, but most of the producers of these photographs were Westerners and Japanese, who were imperial servants of imperialism. In the case of photography, there is a great possibility of distortion of the facts depending on the needs or perspectives of the producers. In order to correct the distortion, not only the contents of the photograph but also the intention of the producer, the production and the communication status should be grasped. This is because the problem of reading photograph records accurately and fairly in an age where there is no real experience is the cornerstone for understanding modern Korea correctly and broadly studying the Modern History of Korea.

• Journal of the Korean GEO-environmental Society
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• v.23 no.5
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• pp.33-39
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• 2022

For a slag-cement-bentonite (slag-CB) cut-off wall, GGBS replaces a part of the cement mixed to build a CB cut-off wall, which is used to block the flow and leakage of pollutants or groundwater; prevent seawater infiltration; and repair or reinforcement an aged embankments. Slag-CB cut-off walls are used in various applications in different fields where groundwater control is required due to its excellent characteristics. Such properties include high strength, low permeability, high durability and chemical resistance. However, despite these advantages, slag-CB cut-off walls are not extensively studied in Korea and thus are not applied in many cases. Particularly, GGBS, which replaces cement in a mixture, has different properties depending on its country of production. Consequently, it is necessary to perform various studies on slag-CB cut-off walls that use GGBS produced in Korea in order to increase its usability. This study has evaluated the bleeding rate, setting time, strength, and permeability in relation to the cement replacement rate of GGBS produced in Korea for slag-CB cut-off walls, with the aim to increase its usability. The evaluation found that slag-CB cut-off walls, made of a mixture containing GGBS produced in Korea, have a lower bleeding rate and permeability, and higher strengththan CB cut-off walls. It was also analyzed that such improved performance is more effective with a higher cement replacement rate of GGBS.

• Clean Technology
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• v.28 no.2
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• pp.193-200
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• 2022

The term environmental, social and governance (ESG) was first used in the 2003 United Nations Environmental Programme Finance Initiative (UNEP FI). Among the three areas of ESG, environment refers to the impact of companies on the environment. Environmental factors address climate change policies and attempts to reduce emissions, waste and natural resource consumption. Social factors refer to the direction in which a company can improve the social impact of stakeholder includes employees, customers, communities, and governments involved in direct or indirect interaction with the organization itself and the company. Governance factors refer to stakeholders who make major decisions, the composition of the board of directors, their diversity and independence, and the internal policies that set limits and expectations for decision-making. Research related to ESG management is part of corporate social responsibility, sustainability, corporate or financial performance, and social responsibility investment. Through case studies and data-based empirical studies, it was confirmed that ESG management companies had positive results for most of the ESG related fields. Through literature analysis of domestic and international ESG history, introduction background, and management performance, this paper presents theoretical, practical implications by confirming that ESG's introduction and operation strategies are strong competitive strategies that directly affect corporate growth by creating attractive factors.

• Journal of The Korean Association For Science Education
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• v.26 no.4
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• pp.527-536
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• 2006

This study investigated the components of science teacher professionalism, the meaning of PCK (Pedagogical Content Knowledge), examples of science PCK, and complementary measures that should be taken to improve teacher professionalism. Six science teachers recommended by their colleagues explained that the science teacher's professionalism (or professional knowledge) consists of science content knowledge, knowledge about teaching, knowledge about learners, and improvement efforts. Science teachers' definition of PCK, which is the professional knowledge that members of the wider society expect teachers to possess, is the teacher's materialized knowledge that aims at students' understanding and PCK is the accumulated know-how of teachers as they strive to make their teaching comprehensible by students. Science teachers also contended that teachers as professionals need to complement an accountability system, acknowledgement of continuous self-developmental efforts, collegiality, and securing validity in the teacher employment test. The teachers argued that the societal recognition of teaching professionalism is essential for a high quality teaching. Suggestions for how to improve science teaching professionalism are also discussed.

• Journal of the Korean GEO-environmental Society
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• v.13 no.12
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• pp.91-98
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• 2012

In this paper, the behavior of offshore wind turbine(OWT) foundation which is modeled by using existing design method and FEM is compared. When the same type of foundation is designed under the same sea and ground condition, the behavior characteristics with each model are compared. As a result, the member forces between apparent fixity and distributed spring type foundation which consider the ground stiffness are not different markedly, while fixed-base type foundation shows relatively lower member forces, which results in smaller safety margin. In other words, considering ground stiffness is reasonable because soil-pile interaction affects significantly on the analysis result. A case study with a monopile shows significant errors between p-y and FEM model at the head and tip of the pile. Also, it shows that the errors at the tip with diameter increase of the pile is larger. Thus, considering ground characteristics and engineering judgment are necessary in practice. A comparison of reliability analysis between tripod and monopile type foundation on the same condition shows larger probability of failure in monopile type and it indicates that the safety margin of monopile type can be lower.

• Journal of The Korean Association For Science Education
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• v.40 no.3
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• pp.347-358
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• 2020

He purpose of this study is to design and apply a pilot assessment tools for scientifically gifted and talented elementary school students with lower grades. The assessment tool consists of three parts: homeroom teachers' recommendation, paper and pencil test and performance tests. The tools are verified whether they are suitable for unique characteristics of young children and enable to attract active participation. For suitability check, students' performance tests were inductively analyzed and 30 behavioral patterns were shown which were included and partially exceeded the level of lower elementary students' performance expectation in NGSS. As a result, we concluded that assessment tool developed in this study will be effective in discriminating young pupils' scientific talents. Then for participation check, we compared the number of coding references as an indicator of participation. Two cases were found that students with high interest participated passively in performance tests. We found these 'passive participants' had excessive scientific experiences and extremely narrow region of interest, during the process of complex interpretation between the results of this assessment tool and in-depth interviews with homeroom teachers. We found out in this study that newly developed tools can be used in school scene after modifying and elaboration through accumulation of more case studies.

• The Korean Journal of Air & Space Law and Policy
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• v.30 no.1
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• pp.303-325
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• 2015

The latest slogan put forth by the international space community is the safety, security, and sustainability of outer space activities. The security of outer space activities, in particular, would be defined as the secure state from space-based threats. The latter comprises passive threats (such as collision with other satellites and space debris) and aggressive threats (such as electromagnetic interference, arms race on the earth or in outer space, and military attacks). Has outer space been used for military purposes in practice? If so, does international law regulate the military space activities it? The use of outer space for military purposes is referred to as space militarization and space weaponisation. Satellites has been used in Gulf War, Kosovo War, and Afghan War, recently, and research and development on space weapons are under way. Since only the placement of weapons of mass destruction on orbit around the earth is prohibited in accordance with 1967 Outer Space Treaty, it may be asked whether other weapons may be placed on orbit. It will be necessary to analyze the stance of on the above question, by studying UN space-related treaties including UN Charter. New international space norms represented by PPWT, ICoC, and UN GGE Report are at the center of progressive development of international law. In conclusion, the author will signpost the various points on international norms to be codified on the use of outer space for military purposes.