• Title/Summary/Keyword: support element

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Structural Analysis of Concrete-filled FRP Tube Dowel Bar for Jointed Concrete Pavements (콘크리트 포장에서 FRP 튜브 다웰바의 역학적 특성 분석)

  • Park, Jun-Young;Lee, Jae-Hoon;Sohn, Dueck-Su
    • International Journal of Highway Engineering
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    • v.13 no.3
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    • pp.21-30
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    • 2011
  • As well known, dowel bars are used to transfer traffic load acting on one edge to another edge of concrete slab in concrete pavement system. The dowel bars widely used in South Korea are round shape steel bar and they shows satisfactory performance under bending stress which is developed by repetitive traffic loading and environment loading. However, they are not invulnerable to erosion that may be caused by moisture from masonry joint or bottom of the pavement system. Especially, the erosion could rapidly progress with saline to prevent frost of snow in winter time. The problem under this circumstance is that the erosion not only drops strength of the steel dower bar but also comes with volume expansion of the steel dowel bar which can reduce load transferring efficiency of the steel dowel bar. To avoid this erosion problem in reasonable expenses, dowers bars with various materials are being developed. Fiber reinforced plastic(FRP) dower that is presented in this paper is suggested as an alternative of the steel dowel bar and it shows competitive resistance against erosion and tensile stress. The FRP dowel bar is developed in tube shape and is filled with high strength no shrinkage. Several slab thickness designs with the FRP dowel bars are performed by evaluating bearing stress between the dowel bar and concrete slab. To calculated the bearing stresses, theoretical formulation and finite element method(FEM) are utilized with material properties measured from laboratory tests. The results show that both FRP tube dowel bars with diameters of 32mm and 40mm satisfy bearing stress requirement for dowel bars. Also, with consideration that lean concrete is typical material to support concrete slab in South Korea, which means low load transfer efficiency and, therefore, low bearing stress, the FRP tube dowel bar can be used as a replacement of round shape steel bar.

Marketing Standardization and Firm Performance in International E.Commerce (국제전자상무중적영소표준화화공사표현(国际电子商务中的营销标准化和公司表现))

  • Fritz, Wolfgang;Dees, Heiko
    • Journal of Global Scholars of Marketing Science
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    • v.19 no.3
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    • pp.37-48
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    • 2009
  • The standardization of marketing has been one of the most focused research topics in international marketing. The term "global marketing" was often used to mean an internationally standardized marketing strategy based on similarities between foreign markets. Marketing standardization was discussed only within the context of traditional physical marketplaces. Since then, the digital "marketspace" of the Internet had emerged in the 90's, and it became one of the most important drivers of the globalization process opening new opportunities for the standardization of global marketing activities. On the other hand, the opinion that a greater adoption of the Internet by customers may lead to a higher degree of customization and differentiation of products rather than standardization is also quite popular. Considering this disagreement, it is notable that comprehensive studies which focus upon the marketing standardization especially in the context of global e-commerce are missing to a high degree. On this background, the two basic research questions being addressed in this study are: (1) To what extent do companies standardize their marketing in international e-commerce? (2) Is there an impact of marketing standardization on the performance (or success) of these companies? Following research hypotheses were generated based upon literature review: H 1: Internationally engaged e-commerce firms show a growing readiness for marketing standardization. H 2: Marketing standardization exerts positive effects on the success of companies in international e-commerce. H 3: In international e-commerce, marketing mix standardization exerts a stronger positive effect on the economic as well as the non-economic success of companies than marketing process standardization. H 4: The higher the non-economic success in international e-commerce firms, the higher the economic success. The data for this research were obtained from a questionnaire survey conducted from February to April 2005. The international e-commerce companies of various industries in Germany and all subsidiaries or headquarters of foreign e-commerce companies based in Germany were included in the survey. 118 out of 801 companies responded to the questionnaire. For structural equation modelling (SEM), the Partial-Least. Squares (PLS) approach in the version PLS-Graph 3.0 was applied (Chin 1998a; 2001). All of four research hypotheses were supported by result of data analysis. The results show that companies engaged in international e-commerce standardize in particular brand name, web page design, product positioning, and the product program to a high degree. The companies intend to intensify their efforts for marketing mix standardization in the future. In addition they want to standardize their marketing processes also to a higher degree, especially within the range of information systems, corporate language and online marketing control procedures. In this study, marketing standardization exerts a positive overall impact on company performance in international e-commerce. Standardization of marketing mix exerts a stronger positive impact on the non-economic success than standardization of marketing processes, which in turn contributes slightly stronger to the economic success. Furthermore, our findings give clear support to the assumption that the non-economic success is highly relevant to the economic success of the firm in international e-commerce. The empirical findings indicate that marketing standardization is relevant to the companies' success in international e-commerce. But marketing mix and marketing process standardization contribute to the firms' economic and non-economic success in different ways. The findings indicate that companies do standardize numerous elements of their marketing mix on the Internet. This practice is in part contrary to the popular concept of a "differentiated standardization" which argues that some elements of the marketing mix should be adapted locally and others should be standardized internationally. Furthermore, the findings suggest that the overall standardization of marketing -rather than the standardization of one particular marketing mix element - is what brings about a positive overall impact on success.

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A RURAL HEALTH SERVICE MODEL FOR KOREA BASED OH A PRIMARY CARE NURSING SERVICE SYSTEM

  • Hong, Yeo-Shin
    • Journal of Korean Academy of Nursing
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    • v.11 no.2
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    • pp.5-8
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    • 1981
  • This study concerns itself with the development of a new model of comprehensive health service for rural communities of Korea. The study was conceived to resolve the problems of both underservice in rural communities and underutilization of valuable health manpower, namely the nurses, the disenchanted elite health personnel in Korea. On review of the current situation, the greatest deficiencies in the Korean health care system were found in the availability of primary care at the peripheries of md communities, in the dissemination of knowledge of disease prevention and health care, and in the induction of and guidance for active participation by the clientele in health maintenance at the personal, family and community level Abundant untapped health resources were identified that could be brough to bear upon the national effort to extend health services to every member of the Korean Population. Therefore, it was Postulated that the problem of underservice in rural communities of Korea can be structurcturally resolved by the effective mobilization and organization of untapped health resources, and that. a primary care Nursing Service System offers the best possibility for fulfillment of rural health service goals within the current health man-power situation. In order to identify appropriate strategies to combat the present difficulties in Korean rural health services and to utilize nurses and other health personnel in community-centered health programs, a search was made for examples of innovative service models throughout the world. An extensive literature survey and field visits to project sites both in Korea and in the United States were made. Experts in the field of world health, health service, planners, administrators, and medical and nursing practitioners in Korea, in the United States as well as visitors from other Asian countries were widely consulted. On the basis of information and inputs from these experts a new rural health service model has been constructed within the conceptual framework of community development, especially of the innovation diffusion Model. It is considered especially important that citizens in each community develop capacities for self-care with assistance and supports from available health professionals and participate in health service-related decisions that affect their own well-being. The proposed model is based upon the regionalization of health care planning utilizing a comprehensive Nursing Service System at the immediate delivery level The model features: (1) a health administration unit at each administrative level; (2) mechanisms for community participation; (3) a continuous source of primary health care at the local community level; (4) relative centralization of specialty care and provision of tertiary or super-specialty care only at major national metropolitan centers; and (5) a system for patient referral to the appropriate level of care. This model has been built around professional nurses as the key community health workers because their training is particularly suited and because large numbers of well-trained nurses are currently available and being trained. The special element in this model is a professional nurse-guided, self-care facilitating primary care Community Nursing Service System. This is supported by a Nursing Extension Service as a new training and support structure. (See attached diagrams). A broad spectrum of programs was proposed for the Community Nursing Service System. These were designed to establish a balance of activities between the clinic-centered individual care component and the field activity-centered educational and supportive component of health care services. Examples of possible program alternatives and proposed guidelines for health care in specific situations were presented, as well as the roles and functions of the key health personnel within the Community Nursing Service System. This Rural Health Service Model was proposed as a real alternative to the maldistributed, inequitable, uncoordinated solo-practice, physician-centered fee-for-service health care available to Koreans today.

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Analysis of Pre-service Science Teachers' Responsive Teaching Types and Barriers of Practice (예비과학교사들의 반응적 교수 유형 및 실행의 제약점 분석)

  • Cho, Mihyun;Paik, Seoung-Hey
    • Journal of The Korean Association For Science Education
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    • v.40 no.2
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    • pp.177-189
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    • 2020
  • In this study, we implemented an education program to improve the responsive teaching ability of pre-service science teachers, and analyzed the responsive teaching practices revealed during the program process. Through this, we derived the types and characteristics of responsive teaching practice, identified factors that made it difficult for pre-service teachers to practice, and obtained empirical data on under what conditions the responsive teaching capacity of pre-service teachers was developed. For this purpose, a practice-based teacher education program was designed and carried out for 14 pre-service teachers who had no experience in responsive teaching. The program consists of four steps; observation of class, practice through rehearsal, application in practicum, and post-reflection on educational practice. In particular, qualitative analysis was conducted on the types of responsive teaching and their detrimental factors revealed during application in practicum. As a result of the analysis, four types were derived; discriminator type, communicator type, guide type, and facilitator type. Each type was identified as having a common responsive teaching step element. The education program implemented in this study was effective for pre-service teachers to recognize the importance of student-participation class and the educational effect of responsive teaching. However, three barriers that prevented pre-service teachers from responsive teaching practice were also analyzed. First was the pressure to achieve specific learning goals within a given class time. Second was the rigid belief of the fixed curriculum. Third was the obsession that the teacher should lead the class. Based on these results, it was suggested that in order to improve the responsive teaching ability of pre-service teachers, it is necessary to support the recognition of breaking out of the thinking the time constraint, the flexibility of the curriculum, and the role of teacher as a class supporter.

A Study Security Measures for Protection of VIP in the G20 Summit (G20 정상회의 시 주(主)행사장에서의 VIP 안전대책 방안에 관한 연구)

  • Lee, Sun-Ki;Lee, Choong-Soo
    • Korean Security Journal
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    • no.24
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    • pp.91-123
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    • 2010
  • The threat factors available for occurrence given G20 Summit Meeting are expected leader terrorism, hostage terrorism, bomb terrorism, public facilities terrorism, and aircraft terrorism. As for the threat groups, which are expected in Korea, the North Korea, Islam extremist group, and the group such as NGO organization of being opposed to international meeting are regarded as having possibility of causing hazard. Thus, the purpose of this study is to suggest VIP Security-measure plans in the main site in preparation for G20 Summit Meeting. Accordingly, each country in the world is adopting 'the principle of Triple Ring' in common. Thus, it elicited a coping plan by 1st line(inner ring) 2nd line(middle ring) 3rd line(outer ring) based on this principle, and proposed even an opinion together that will need to be reflected in light of policy for the VIP security measures. In conclusion, as for the VIP Security-measure plans in the main site in preparation for G20 Summit Meeting, In the inner ring(safety sector), first, an intercepting measure needs to be devised for a spot of getting into and out of vehicles given the Straight Street. Second, the Walking Formation needs to be reinforced boldly in the exposed area. In the middle ring(security sector), first, the control plan needs to be devised by considering particularity of the main site. Second, there is necessity for adopting the efficient security badge operation plan that is included RFID function within security badge. In the outer ring(aid protective sector), first, there is necessity of preparing for several VIP terrorisms, of collecting information and intelligence, and of reinforcing the information collection system against terrorism under the cooperation with the overseas information agency. Second, the urgent measure training in time of emergency needs to be carried out toward security agent event manpower. Third, to maintain the certain pace in VIP motorcade, the efficient traffic control system needs to be operated. Finally, as for what will need to be reflected in light of policy for VIP security measures, first, there is necessity for allowing VIP residence to be efficiently dispersed to be distributed and controlled. Second, there is necessity for allowing impure element to misjudge or attack to be failed by utilizing diverse deception operations. Third, according to the reorganization in North Korea's Organization of the South Directed Operations, the powerful 'military-support measure' needs to be driven from this G20 Summit Meeting. For this, the necessity was proposed for further reinforcing the front back defense posture under the supervision of the Ministry of National Defense and for positively coping even with detecting and removing poison in preparation for CBR (chemical, biological, and radio-logical) terrorism.

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Suppressive Effects of Defatted Green Tea Seed Ethanol Extract on Cancer Cell Proliferation in HepG2 Cells (HepG2 Cell에서 녹차씨박 에탄올 추출물의 암세포 증식 억제효과)

  • Noh, Kyung-Hee;Min, Kwan-Hee;Seo, Bo-Young;Kim, Hye-Ok;Kim, So-Hee;Song, Young-Sun
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.40 no.6
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    • pp.767-774
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    • 2011
  • Defatted green tea seed was extracted with 100% ethanol for 4 hr and then fractionated with petroleum ether, ethyl acetate and butanol. The ethanol and butanol extracts showed greater increases in antiproliferation potential against liver cancer cells than petroleum ether, ethyl acetate, $H_2O$, and hot water extracts did. Thus, this study was carried out to investigate the anti-proliferative actions of defatted green tea seed ethanol extract (DGTSE) in HepG2 cancer cells. The DGTSE contained catechins including EGC ($1039.1{\pm}15.2\;g/g$), tannic acid ($683.5{\pm}17.61\;{\mu}g/g$), EC ($62.4{\pm}5.00\;{\mu}g/g$), ECG ($24.4{\pm}7.81\;{\mu}g/g$), EGCG ($20.9{\pm}0.96\;{\mu}g/g$) and gallic acid ($2.4{\pm}0.68\;{\mu}g/g$), but caffeic acid was not detected when analyzed by HPLC. The anti-proliferation effect of DGTSE toward HepG2 cells was 83.13% when treated at $10\;{\mu}g$/mL, of DGTSE, offering an $IC_{50}$ of $6.58\;{\mu}g$/mL. DGTSE decreased CYP1A1 and CYP1A2 protein expressions in a dose-dependent manner. Quinone reductase and antioxidant response element (ARE)-luciferase activities were increased about 2.6 and 1.94-fold at a concentration of $20\;{\mu}g$/mL compared to a control group, respectively. Enhancement of phase II enzyme activity by DGTSE was shown to be mediated via interaction with ARE sequences in genes encoding the phase enzymes. DGTSE significantly (p<0.05) suppressed prostaglandin $E_2$ level, tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) protein expressions, and NF${\kappa}$B translocation, but did not affected nitric oxide production. From the above results, it is concluded that DGTSE may ameliorate tumor and inflammatory reactions through the elevation of phase II enzyme activities and suppression of NF${\kappa}$B translocation and TNF-${\alpha}$ protein expressions, which support the cancer cell anti-proliferative effects of DGTSE in HepG2 cells.

Fernand Khnopff's Belgian Symbolism and Nationalism in I Lock My Door upon Myself (페르낭 크노프(Fernand Khnopff)의 작품에 나타난 벨기에 상징주의와 내셔널리즘)

  • Chung, Y.-Shim
    • 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."

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A study of quality of working life to dental hygienist's (치과위생사의 근로생활의 질(QWL)에 관한 연구)

  • Oh, Hye-Seung;Kim, Eun-Hee
    • Journal of Korean society of Dental Hygiene
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    • v.10 no.2
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    • pp.375-392
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    • 2010
  • Objectives : Dental hygienist's work satisfaction and stress affect the overall quality of work life(QWL). Therefore, this research is intended to suggest fundamental data to improve QWL by finding out characteristics of each work satisfaction and stress element. To this end, a total of 327 dental hygienists working at general hospitals, university hospitals, dental hospitals and dental clinics across Seoul, Gyeonggi and Incheon were surveyed. Results of survey are as follows. Methods : The collected data were analyzed by using an SPSS 12.0 statistical program, obtaining the following results. The collected data conducted a questionnaire survey for 327 dental hygienists who work at the hospitals, university hospitals, dental hospitals, and dental clinics located at Seoul, Gyeonggi-do, and Incheon district from January until March, 2009, and drew the conclusions as follows. Result : 1. Demographic characteristics, income from 1.5 to 1.99 million were the whole lot, more than 2 million to less than 1.5 million was similar. Marital status Married Unmarried higher than the atheist religion, Christianity, Catholicism, Buddhism, and other, respectively. Classification by level of education in the college graduate, university graduate, graduate diploma, respectively. 2. Are working in a job-related characteristics of dentistry, dental hospital, general and university hospital, respectively. The making in position, Mount, contractor, responsible, senior, was an intern in the order. The five-day workweek whether working at night and is not going to care whether the conduct was similar. Classification of working hours and 8 hours, 8 hours, 8 hours or less orderly, and total of less than 1-3 years of clinical experience, 5 years, less than one year, less than 3-5 years, respectively. 3. There comes out a significant difference according to age, income, position, gross clinical experience, and whether to put night shift into practice in job stability in terms of the quality subsequent to general characteristics(p<.05). 4. There comes out a significant difference according to marital status, one's place of work, position, whether to put a five-day workweek into practice in work environment and benefits package in terms of the quality subsequent to general characteristics (p<.05). 5. There comes out a significant difference according to age, marital status, income, position, and gross clinical experience in education & training and benefits packages in terms of the quality subsequent to general characteristics(p<.05). 6. There comes out a significant difference according to whether to put night medical treatment into practice in social usefulness in terms of the quality subsequent to general characteristics(p<.05). 7. There comes out a significant difference according to marital status, income, one's place of work, gross clinical experience, work hours, and whether to put a five-day workweek into practice in leisure activity in terms of the quality subsequent to general characteristics(p<.05). 8. There comes out a significant difference according to income, one's place of work, and position in wage level in terms of the quality subsequent to general characteristics(p<.05). 9. There was no significant difference in all items related to human relations and free communication in terms of the quality subsequent to general characteristics(p>.05). Conclusions : It is necessary to analyze factors related to work satisfaction and stress in order to improve dental hygienist's quality of work life. Hospitals must support them systematically and institutionally and related organizations must conduct practical research.

"Legal Study on Boundary between Airspace and Outer Space" (영공(領空)과 우주공간(宇宙空間)의 한계(限界)에 관한 법적(法的) 고찰(考察))

  • Choi, Wan-Sik
    • The Korean Journal of Air & Space Law and Policy
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    • v.2
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    • pp.31-67
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    • 1990
  • One of the first issues which arose in the evolution of air law was the determination of the vertical limits of airspace over private property. In 1959 the UN in its Ad Hoc Committee on the Peaceful Uses of Outer Space, started to give attention to the question of the meaning of the term "outer space". Discussions in the United Nations regarding the delimitation issue were often divided between those in favour of a functional approach ("functionalists"), and those seeking the delineation of a boundary ("spatialists"). The functionalists, backed initially by both major space powers, which viewed any boundary as possibly restricting their access to space(Whether for peaceful or military purposes), won the first rounds, starting with the 1959 Report of the Ad Hoc Committee on the Peaceful Uses of Outer Space which did not consider that the topic called for priority consideration. In 1966, however, the spatialists, were able to place the issue on the agenda of the Outer Sapce Committee pursuant to Resolution 2222 (xxx1). However, the spatialists were not able to present a common position since there existed a variety of propositions for delineation of a boundary. Over the years, the funtionalists have seemed to be losing ground. As the element of location is a decisive factor for the choice of the legal regime to be applied, a purely functional approach to the regulation of activities in the space above the Earth does not offer a solution. It is therefore to be welcomed that there is clear evidence of a growing recognition of the defect inherent to such an approach and that a spatial approach to the problem is gaining support both by a growing number of States as well as by publicists. The search for a solution of the problem of demarcating the two different legal regimes governing the space above the Earth has undoubtedly been facilitated, and a number of countries, among them Argentina, Belgium, France, Italy and Mexico have already advocated the acceptance of the lower boundary of outer space at a height of 100km. The adoption of the principle of sovereignty at that height does not mean that States would not be allowed to take protective measures against space activities above that height which constitute a threat to their security. A parallel can be drawn with the defence of the State's security on the high seas. Measures taken by States in their own protection on the high seas outside the territorial waters-provided that they are proportionate to the danger-are not considered to infringe the principle of international law. The most important issue in this context relates to the problem of a right of passage for space craft through foreign air space in order to reach outer space. In the reports to former ILA Conferences an explanation was given of the reasons why no customary rule of freedom of passage for aircraft through foreign territorial air space could as yet be said to exist. It was suggested, however, that though the essential elements for the creation of a rule of customary international law allowing such passage were still lacking, developments apperaed to point to a steady growth of a feeling of necessity for such a rule. A definite treaty solution of the demarcation problem would require further study which should be carried out by the UN Outer Space Committee in close co-operation with other interested international organizations, including ICAO. If a limit between air space and outer space were established, air space would automatically come under the regime of the Chicago Convention alone. The use of the word "recognize" in Art. I of chicago convention is an acknowledgement of sovereignty over airspace existing as a general principle of law, the binding force of which exists independently of the Convention. Further it is important to note that the Aricle recognizes this sovereignty, as existing for every state, holding it immaterial whether the state is or is not a contracting state. The functional criteria having been created by reference to either the nature of activity or the nature of the space object, the next hurdle would be to provide methods of verification. With regard to the question of international verification the establishment of an International Satelite Monitoring Agency is required. The path towards the successful delimitation of outer space from territorial space is doubtless narrow and stony but the establishment of a precise legal framework, consonant with the basic principles of international law, for the future activities of states in outer space will, it is still believed, remove a source of potentially dangerous conflicts between states, and furthermore afford some safeguard of the rights and interests of non-space powers which otherwise are likely to be eroded by incipient customs based on at present almost complete freedom of action of the space powers.

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Evaluating Impact Resistance of Externally Strengthened Steel Fiber Reinforced Concrete Slab with Fiber Reinforced Polymers (섬유 보강재로 외부 보강된 강섬유 보강 콘크리트 슬래브의 충격저항성능 평가)

  • Yoo, Doo-Yeol;Min, Kyung-Hwan;Lee, Jin-Young;Yoon, Young-Soo
    • Journal of the Korea Concrete Institute
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    • v.24 no.3
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    • pp.293-303
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    • 2012
  • Recently, as construction technology improved, concrete structures not only became larger, taller and longer but were able to perform various functions. However, if extreme loads such as impact, blast, and fire are applied to those structures, it would cause severe property damages and human casualties. Especially, the structural responses from extreme loading are totally different than that from quasi-static loading, because large pressure is applied to structures from mass acceleration effect of impact and blast loads. Therefore, the strain rate effect and damage levels should be considered when concrete structure is designed. In this study, the low velocity impact loading test of steel fiber reinforced concrete (SFRC) slabs including 0%~1.5% (by volume) of steel fibers, and strengthened with two types of FRP sheets was performed to develop an impact resistant structural member. From the test results, the maximum impact load, dissipated energy and the number of drop to failure increased, whereas the maximum displacement and support rotation were reduced by strengthening SFRC slab with FRP sheets in tensile zone. The test results showed that the impact resistance of concrete slab can be substantially improved by externally strengthening using FRP sheets. This result can be used in designing of primary facilities exposed to such extreme loads. The dynamic responses of SFRC slab strengthened with FRP sheets under low velocity impact load were also analyzed using LS-DYNA, a finite element analysis program with an explicit time integration scheme. The comparison of test and analytical results showed that they were within 5% of error with respect to maximum displacements.