• Journal of the Korean Society of Safety
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• v.34 no.6
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• pp.7-12
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• 2019

Flux Cored Arc Welding (FCAW), which has been widely used in many industries, was developed in the 1950s to supplement shortcomings of the Shielded Metal Arc Welding (SMAW). FCAW has an advantage in that it can weld regardless of postures and give good quality results in the filed with many different working conditions. In this study, SM490A (rolled steel for welding structural purpose) with different thicknesses (L:25T+R:30T) were welded using FCAW. Then the mechanical properties (tension test, bending test, hardness test, impact test and macro test) were analyzed and the following conclusions were drawn. In the tensile test, it exceeds the KS standard tensile strength range (400~510) in all welding positions, which means there is a problem in the tensile force transmission performance. In the bending test, it was found that most of the specimens did not exhibit surface rupture or other defects during bending test and they exhibit sufficient toughness even after plastic deformation. In the hardness test, all the results were lower than the standard value of 350 Hv of KS B 0893, which means they have good hardness. In the impact test, all results were larger than the KS reference value of 27J. In the macro test, they showed uniform structure state by the shape of the weld, and there was risk of lamination because no internal defects, bubbles, or impurities were found on the surface of the weld.

• Korean Journal of Construction Engineering and Management
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• v.22 no.3
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• pp.12-20
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• 2021

In order to secure construction quality and safety and prevent cost disputes, the importance of calculating 'the appropriate construction period' has recently emerged. It is necessary to analyze a considerable amount of historical data to establish the standard for calculating the construction period. However, many experts are raising questions about the use of past data due to changes in the construction business environment, such as shortening working hours, reinforcing quality regulations, and changing climate conditions. In addition, the possibility of errors increases when calculating a uniform construction period using historical statistics because the work order and productivity are very diverse according to construction conditions. Therefore, through this study, a new solution to change from the method of analyzing past data to the method of reviewing current production data through an active 'transformation of thoughts' was proposed through this study. In other words, the process of reviewing and calculating 'the appropriate construction period' was institutionalized by introducing 'process management experts' and 'construction experts by type of construction' in the design stage.

• Journal of the Korea Society of Computer and Information
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• v.26 no.11
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• pp.183-189
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• 2021

In this study, we developed a "Korean-style button mushroom cultivation Compost post-fermentation system." The purpose is to increase farm income by reducing the labor force of button mushrooms farmers and shortening the production cycle. The "Korean-style button mushroom cultivation Compost post-fermentation system" was designed to reflect the reality of domestic button mushroom farmers. By reducing the temperature difference of the fermentation Compost in the fermentation system, the company produces a button mushroom Compost that ensures uniform quality. As a result of the performance experiment, the working time of the Compost post-fermentation system was shortened by 40 hours. The number of aerobic bacteria and actinomyces that help the button mushrooms Compost increased. Filamentous bacteria that deteriorate the quality of mushrooms have been sterilized.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.35 no.3
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• pp.67-77
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• 2019

The purpose of this study is to introduce a town management system that utilizes private sectors and public space resources in urban management area. In this study, we are studying 7 town management districts in Japan which have been establishing diverse management systems that are propelled by the private sectors and private fund. We analyzed qualitative characteristics of 7 town management districts by surveying the operating status of organization, financial management and activities. Through the analysis, we clarified their characteristics that are related to establishing background. Also, we suggested conclusions of the study as follows: First of all, it is important to develop a town management method that takes into account the characteristics of the target district in order to overcome the limitation of applying uniform method and increase sustainability and efficiency of privately-led urban management. Second, marketing and promotion are critical strategies in town management since they are satisfying both private and public benefits. The high rate of reinvestment in marketing and promotions shows efforts to maintain the asset value of the private sector and continue to revitalize the city. Finally, in order to carry out urban management with private initiative, it is necessary to establish a working organization capable of realizing the operational direction of the steering committee to secure the executive power.

• Structural Engineering and Mechanics
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• v.83 no.3
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• pp.341-351
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• 2022

During bolted flange assembly, the contact stiffness of some areas of the joint surface may be low due to the elastic interaction. In order to improve the contact stiffness at the lowest position of bolted flange, the correlation model between the initial bolt pre-tightening force and the contact stiffness of bolted flange is established in this paper. According to the stress distribution model of a single bolt, an assumption of uniform local contact stiffness of bolted flange is made. Moreover, the joint surface is divided into the compressive stress region and the elastic interaction region. Based on the fractal contact theory, the relationship model of contact stiffness and contact force of the joint surface is proposed. Considering the elastic interaction coefficient method, the correlation model of the initial bolt pre-tightening force and the contact stiffness of bolted flange is established. This model can be employed to reverse determine the tightening strategy of the bolt group according to working conditions. As a result, this provides a new idea for the digital design of tightening strategy of bolt group for contact stiffness of bolted flange. The tightening strategy of the bolted flange is optimized by using the correlation model of initial bolt pre-tightening force and the contact stiffness of bolted flange. After optimization, the average contact stiffness of the joint surface increased by 5%, and the minimum contact stiffness increased by 6%.

• Journal of the Korean institute of surface engineering
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• v.56 no.1
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• pp.62-68
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• 2023

Silicon (Si) is considered as a promising substitute for the conventional graphite due to its high theoretical specific capacity (3579 mAh/g, Li₁₅Si₄) and proper working voltage (~0.3V vs Li⁺/Li). However, the large volume change of Si during (de)lithiation brings about severe degradation of battery performances, rendering it difficult to be applied in the practical battery directly. As a one feasible candidate of industrial Si anode, silicon monoxide (SiO_x) demonstrates great electrochemical stability with its specialized strategy, downsized Si nanocrystallites surrounded by Li⁺ inactive buffer phase (Li₂O and Li₄SiO₄). Nevertheless, SiO_x inherently has the initial irreversible capacity and poor electrical conductivity. To overcome those issues, conformal carbon coating has been performed on SiO_x utilizing ethylbenzene as the carbon precursor of chemical vapor deposition (CVD). Through various characterizations, it is confirmed that the carbon is homogeneously coated on the surface of SiO_x. Accordingly, the carbon-coated SiOx from CVD using ethylbenzene demonstrates 73% of the first cycle efficiency and great cycle life (88.1% capacity retention at 50th cycle). This work provides a promising synthetic route of the uniform and scalable carbon coating on Si anode for high-energy density.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.4
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• pp.359-371
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• 2008

Purpose: The purpose of this study was to investigate the stress distribution in mandibular implant overdentures with telescopic crowns compared to bar attachment. Material and methods: Three-dimensional finite element models consisting of the mandibular bone, 4 implants, and primary bar-splinted superstructure or secondary splinted superstructure with telescopic crowns were created. Vertical and oblique loads were directed onto the occlusal areas of the superstructures to simulate the maximal intercuspal contacts and working contacts such as group function occlusion. Maximum stress and stress distribution were analysed in mandibular bone, implant abutments, and superstructures. Results: 1. In comparison of von Mises stress on mandibular bone, telescopic overdenture had a little lower stress values in vertical load and working side load except oblique load. In the mandible, the telescopic overdenture distributed more uniform stress than the bar overdenture. 2. In comparison of von Mises stress on implant abutments, telescopic overdenture had much lower stress values in all load conditions. In implant abutments, the telescopic overdenture distributed stress similar to the bar overdenture. Stress was concentrated on the distal surfaces of the posterior implant abutments in both mandibular overdentures. 3. In comparison of von Mises stress on superstructures, the telescopic overdenture had much more stress values in all load conditions. However, the telescopic overdenture distributed more uniform stress on superstructure than the bar overdenture. In the bar overdenture, stress was concentrated on each cental area of bar structures and connected area between implant abutments and bar structures. Conclusion: In the results of this study, the telescopic overdenture had lower stress values than the bar overdenture in mandibular bone and implant abutments, but more stress values in superstructures. However, if optimal material was selected in making superstructures, the telescopic overdenture was compared to the bar overdenture in stress distribution.

• The Korean Journal of Air & Space Law and Policy
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• v.4
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• pp.7-35
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• 1992

The expansion of air transport on a global scale with ever increasing traffic densities has brought about problems that must be solved through new multilateral mechanisms. Looking to the immediate future, air transport will require new forms of international cooperation in technical and economic areas. Air transport by its very nature should have been a counterforce to nationalism. Yet, the regulatory system in civil aviation is still as firmly rooted in the principle of national sovereignty as when it was first proclaimed at t-11e Paris Convention of 1919 and reaffirmed in the Chicago Convention. Sovereignty over the airspace has remained the cornerstone of relations between states in all respects of air transport. The importance of sovereignty over air space embodied in article 1 of the Chicago Conrenton also is responsible for restricting the authority of ICAO as an intergovernmental regulatory agency. The Orgenization, for all its extensive efforts, has only limited authority. ICAO sets standards but cannot enforce them; it devises solutions but cannot impose them. To implement its rules ICAO most rely not so much on legal requirements as on the goodwill of states. It has been forty-eight years since international community set the foundations of the international system in civil aviation action. Profound political, economic and technological changes have taken place in air transport. The Chicago Convention is living proof that staes can work together to make air transport a safe mode of travel. The law governing international civil auiation is principally based on international treaties and on other regulation agreed to by governments, for the most part through the mechanism of ICAO. The role of ICAO international standards and recommended practices and procedures dealing with a broad range of technical matters could hardly be overestimated. The organization's ability to develop these standards and procedures, to adapt them continuously to the rapid sate of change and development of air transport, should be particularly stressed. The role of ICAO in the area of the development of multilateral conventions on international air law has been successful but to a certain degree. From the modest starting-point of the Tokyo Convention, we have seen more adequate international instruments prepared within the scope of ICAO activities, adopted: the Hague Convention of 1970 for the suppression of Unlawful Seizure of Aircraft and the Montreal Convention of 1971 for the Suppression of Unlawful Acts against the Safety of Civil Aviation. The work of ICAO in the new domain of international law conventions concerning what has been loosely termed above as the criminal problems connected with international air transport, in particular the problem of armed aggression against aircraft, should be positively appreciated. But ICAO records in the domain of developing a uniform legal system of international carriage by air are rather disappointing. The problem of maintaining and developing the uniformity of this regulation exceeds the scope of interest and competence of governmental transport agencies. The expectations of mankind linked to it are too great to give up trying to restore the uniform legal system of international air carriage that would create proper conditions for its further growth. It appears that ICAO has, at present, a good opportunity for doing this. The hasty preparation of ICAO draft conventions should be definitely excluded. Every Preliminary draft convention ought to be sent to Governments of all member-States for consideration, So that they could in form ICAO in due time of their observation. The problom of harmonizing a uniform law of international air carriage with that of other branches of international transport should demand more and more of its attention. ICAO cooperation with other international arganization, especially these working in the field of international transport, should be strengthened. ICAO is supposed to act as a link and a mediator among, at times the conflicting interests of member States, serving the happiness and peace of all of the world. The transformation of the contemporary world of developing international relations, stimulated by steadily growing international cooperation in its various dimensions, political, economic, scientific, technological, social and cultural, continuously confronts ICAO with new task.

• (The)Korea Educational Review
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• v.15 no.1
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• pp.107-132
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• 2009

What is good instruction? The term "instruction" means the essential activity of school education, a precondition for good school, and the starting point of reforming school education. The purpose of this study is to investigate the meaning of "good instruction" by examining the difference of perception between in-service teachers and pre-service teachers who encompass the viewpoint of both teacher and student using open-ended questionnaires asking the type of instruction that they have to avoid and the undesirable instruction. This study was carried out with 150 teachers who were working in the schools and 160 students who were in college of education to be teacher in the future. Collected data was analyzed using the QSR Nvivo qualitative program. The findings of this study indicates the followings: First, the most undesirable class cited by in-service teachers was the class that applies uniform instructional strategy, followed by class based on directions instruction, unsystematic class, class characterized by lack of teaching competency, class that emphasizes test scores and competition, class that are not interactive enough, class that does not consider the level of students, class in which students are not respected, class that have poor educational environment, and the class in which little support is provided. Second, the most undesirable class cited by pre-service teachers was the class that applies uniform instructional strategy, followed by unsystematic class, class characterized by lack of teaching competency, class based on directions instruction, class in which students are not respected, class that emphasizes test scores and competition, class that does not consider the level of students, class that are not interactive enough, class that have poor educational environment, and the class in which little support is provided. Third, this study examined the difference of perception between in-service teachers and pre-service teachers toward the undesirable class that they have to avoid. In terms of the integrated rank that is common among in-service teachers and pre-service teachers, the most undesirable class that they have to avoid was the class that applies uniform instructional strategy, unsystematic class, class based on directions instruction, and class characterized by lack of teaching competency. The findings of this study may be used as a basis for in-service teachers to reflect on their professionalism of instruction that they provide and examine the attitude of students toward instruction, while providing a practical guideline for pre-service teachers to design and ensure systematic instruction in the future.

• The Journal of Art Theory & Practice
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• no.9
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• pp.171-193
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• 2010

This paper examines Fernand Khnopff's Symbolism, focusing on the I Lock My Door upon Myself as a manifesto of his artistic credo in style and theme. Its title was originally in English, originating from the poem "Who Shall Deliver Me?" by Dante Gabriel Rossetti's sister Christina Rossetti. I use the term "Social Symbolism" which combines a nationalist perspective with traditional French Symbolism, in order to explain how the image of Bruges is represented in his oeuvre. Symbolism calls for psychological introspection evoking death, love, silence, and solitude and recluse from realty in pursuit of the Unknown and the Ideal. Although Khnopff shared this idea, he departed from symbolist tradition by incorporating a political milieu in his paintings. First, I discuss Khnopff's early stage in the formation of his artistic concept, including his family background as well as his early opportunity to visit the Exposition Universelle in Paris where he formed his early interests in aesthetics, philosophy, literature, mythology and Egyptian art. His early works, La Painture, la Musique, la Poesie(1880-1881), Le Crise(1881), and En ecoutant Schuman(1883) reveal his favorite subjects which were quite prevalent in the symbolist traditions of both Belgium and France. By looking at Khnopff's paintings, I endeavor to situate his Symbolism in the context of the development of Belgian modernity and cultural nationalism. Second, my analysis of Khnopff creates a new overview of Symbolism in Europe, especially in Belgium. In the absence of socio-political integration, the Symbolist painter adds nostalgic meaning to the landscape of Bruges. The scene of Bruges illuminates the social atmosphere in Belgium at that time. Since Belgium became an independent country, it tried to differentiate its own cultural and national identity from France. There was a powerful social movement for Belgium to claim its own identity, language, and culture. Bruges was, for Symbolists, the epitome of Belgium's past glory. This encouraged the formation of Belgian nationalism centering on Brussels, as I demonstrate in Khnopff's Bruges-la-Morte(1892). The relationship between Symbolist artist and writers is crucial for understanding this development. Khnopff, for instance, illustrated or provided frontispieces for many Symbolist writers such as Rodenbach, Peladan, Spencer and Le Roy. Khnopff did not objectify the exact meaning, but rather provided his own subjective interpretation. In this respect, I Lock My Door, inspired by Rossetti, started from the same motif, but Khnopff seeked escape into silence and death while Rossetti searched for Christian salvation. Finally my paper deals with the social context in which Khnopff worked. He was a founding member of Les XX in 1883 and later La Libre Esthethetique he also participated in the exhibition of le Salon de la Rose + Croix. Les XX was not a particular school of art and did not have a uniform manifesto, but its exhibitions focused on decorative arts by encompassing art for all people via common, everyday objects. The Periodical, L'art moderne was founded to support this ideal by Edmond Picard and Maux. Les XX declared art as independent art, detached from all official connections. Khnopff designed the 1890 catalogue cover of Les XX and the 1891 cover. These designs show decorative element of Art Nouveau in an early example of "modern poster." Les XX pursued all art including graphic arts, prints, placard, posters and book illustrations and design. These forms of art were l'art social and this movement was formed by the social atmosphere in Belgium in terms of social reforms and strikes by working class. Khnopff designed the book cover for la Maison du Peuple. The artist, however, did not share the ideal egalitarianism of the working class to a certain degree, while he was working in his villa he designed under the ideal motto, "on n'a pas que," he expressed the nihilistic emotions toward society by the theme of interiority such as solitude, silence, narcissism, introspection, and introversion. In the middle of his Symbolism, we find the "cultural nostalgia" or longing that the artist develops in the I Lock My Door upon Myself. Khnopff's longing toward the lost city of "Bruges" form the crux of his "Social Symbolism."