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Diverse modeling techniques, parameters, and assumptions for nonlinear dynamic analysis of typical concrete bridges with different pier-to-deck connections: which to use and why

  • Morkos, B.N.;Farag, M.M.N.;Salem, S.;Mehanny, S.S.F.;Bakhoum, M.M.
    • Earthquakes and Structures
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    • v.22 no.3
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    • pp.245-261
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    • 2022
  • Key questions to researchers interested in nonlinear analysis of skeletal structures are whether the distributed plasticity approach - albeit computationally demanding - is more reliable than the concentrated plasticity to adequately capture the extent and severity of the inelastic response, and whether force-based formulation is more efficient than displacement-based formulation without compromising accuracy. The present research focusing on performance-based seismic response of mid-span concrete bridges provides a pilot holistic investigation opting for some hands-on answers. OpenSees software is considered adopting different modeling techniques, viz. distributed plasticity (through either displacement-based or force-based elements) and concentrated plasticity via beam-with-hinges elements. The pros and cons of each are discussed based on nonlinear pushover analysis results, and fragility curves generated for various performance levels relying on incremental dynamic analyses under real earthquake records. Among prime conclusions, distributed plasticity modeling albeit inherently not relying on prior knowledge of plastic hinge length still somewhat depends on such information to ensure accurate results. For instance, displacement-based and force-based approaches secure optimal accuracy when dividing, for the former, the member into sub-elements, and satisfying, for the latter, a distance between any two consecutive integration points, close to the expected plastic hinge length. On the other hand, using beam-with-hinges elements is computationally more efficient relative to the distributed plasticity, yet with acceptable accuracy provided the user has prior reasonable estimate of the anticipated plastic hinge length. Furthermore, when intrusive performance levels (viz. life safety or collapse) are of concern, concentrated plasticity via beam-with-hinges ensures conservative predicted capacity of investigated bridge systems.

Government Procurement in the TPP: Differences with GPA, and Implications for Korea's Future Market Opening Negotiations (TPP 정부조달분야: GPA와의 차이 및 향후 한국의 정부조달 시장개방 협상에 대한 함의)

  • Yang, Jun-Sok
    • Korea Trade Review
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    • v.42 no.4
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    • pp.185-215
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    • 2017
  • While the future of Trans-Pacific Partnership Agreement is uncertain, TPP did succeed in convincing certain developing countries, which had been reluctant to open its government procurement market in the past, to open their markets. In this paper, we compare the government procurement chapter of TPP with WTO Government Procurement Agreement to see what factors may have convinced these countries to open their government procurement markets. The key factors seem to be an initially very high levels of threshold, coupled with an extended transition period (up to 20 years) to lower the threshold to figures comparable to other countries; and reduction of legal and regulatory burdens dealing with some transparency and procedural requirements. Korea should use these strategies in their future FTA negotiations to try to open foreign government procurement markets. If Korea wants to accede to TPP, it should have very few problems since Korea has similar threshold levels as current TPP members, and legal and regulatory requirements are more strict under GPA, of which Korea is a member.

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Experimental and analytical study on RC beam reinforced with SFCB of different fiber volume ratios under flexural loading

  • Lin, Jia-Xiang;Cai, Yong-Jian;Yang, Ze-Ming;Xiao, Shu-Hua;Chen, Zhan-Biao;Li, Li-Juan;Guo, Yong-Chang;Wei, Fei-Fei
    • Steel and Composite Structures
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    • v.45 no.1
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    • pp.133-145
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    • 2022
  • Steel fiber composite bar (SFCB) is a novel type of reinforcement, which has good ductility and durability performance. Due to the unique pseudo strain hardening tensile behavior of SFCB, different flexural behavior is expected of SFCB reinforced concrete (SFCB-RC) beams from traditional steel bar reinforced concrete (S-RC) beams and FRP bar reinforced concrete (F-RC) beams. To investigate the flexural behavior of SFCB-RC beam, four points bending tests were carried out and different flexural behaviors between S/F/SFCB-RC beams were discussed. An flexural analytical model of SFCB-RC beams is proposed and proved by the current and existing experimental results. Based on the proposed model, the influence of the fiber volume ratio R of the SFCB on the flexural behavior of SFCB-RC beams is discussed. The results show that the proposed model is effective for all S/F/SFCB-RC flexural members. Fiber volume ratio R is a key parameter affecting the flexural behavior of SFCB-RC. By controlling the fiber volume ratio of SFCB reinforcements, the flexural behavior of the SFCB-RC flexural members such as bearing capacity, bending stiffness, ductility and repairability of SFCB-RC structures can be designed.

Perception of Entrepreneurs on the Startup Ecosystem in the Daegu (대구지역 창업생태계에 대한 창업자들의 인식)

  • Kim Dae-Geun;Bae Sung-Hyun;Kim Jeong-Hun;Ju Ki Jung
    • The Journal of the Convergence on Culture Technology
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    • v.9 no.5
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    • pp.549-555
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    • 2023
  • The main point related to the entrepreneurial ecosystem is that in an environment where a good entrepreneurial ecosystem has been established, startup companies can generate good results. From this perspective, this study examined the perception of entrepreneurs regarding the entrepreneurial ecosystem in the Daegu by conducting an analysis of importance and satisfaction towards the Daegu entrepreneurial ecosystem, using the results of the Innovation Entrepreneurial Ecosystem Establishment and Operation Project of the Daegu Creative Economy Innovation Center, which is a key member of the entrepreneurial ecosystem. The analysis results showed that the importance and satisfaction of the entrepreneurial infrastructure were classified as high, while the importance and satisfaction of finance (investment and support) and securing human resources were shown to be low. Based on the results of this study, we confirmed the perception of entrepreneurs regarding the entrepreneurial ecosystem in Daegu and provided implications for improving the regional entrepreneurial ecosystem and policy directions.

A Study on the Effectiveness of Sanctions against Russian Energy Sector-Focusing on the Oil and Gas Sector (대러 에너지 제재의 효과성에 대한 연구 -석유가스 부문을 중심으로)

  • Won-Soon Kwon;Ju-young Ko
    • Korea Trade Review
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    • v.48 no.1
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    • pp.165-191
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    • 2023
  • The US and EU have imposed energy sanctions on the Russian oil and gas sector in response to the Ukraine crisis. One of the key measures is to cut oil and gas imports from Russia. The US and EU are both the senders of sanctions against Russia. However, there is a fundamental difference between them. While the US is the net oil and gas exporter, most EU member states are heavily dependent on Russian oil and gas. If the US and other major oil and gas exporting countries can replace Russia in the EU energy market, the effectiveness of energy sanctions against Russia can be guaranteed. Our result shows that it is difficult for the major oil and gas exporters to fully replace Russia in the short run because of the lack of additional production capacity and infrastructure. We conclude that the US and EU's energy sanctions against Russia can not guarantee its effectiveness. We argue that other measures, such as diplomacy, should be taken to settle the conflicts in Ukraine.

Ginsenoside 20(S)-Rg3 reduces KIF20A expression and promotes CDC25A proteasomal degradation in epithelial ovarian cancer

  • Rong Zhang;Lei Li;Huihui Li;Hansong Bai;Yuping Suo;Ju Cui;Yingmei Wang
    • Journal of Ginseng Research
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    • v.48 no.1
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    • pp.40-51
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    • 2024
  • Background: Ginsenoside 20(S)-Rg3 shows promising tumor-suppressive effects in ovarian cancer via inhibiting NF-kB signaling. This study aimed to explore the downstream tumor suppressive mechanisms of ginsenoside Rg3 via this signaling pathway. Materials and methods: A systematical screening was applied to examine the expression profile of 41 kinesin family member genes in ovarian cancer. The regulatory effect of ginsenoside Rg3 on KIF20A expression was studied. In addition, we explored interacting proteins of KIF20A and their molecular regulations in ovarian cancer. RNA-seq data from The Cancer Genome Atlas (TCGA) was used for bioinformatic analysis. Epithelial ovarian cancer cell lines SKOV3 and A2780 were used as in vitro and in vivo cell models. Commercial human ovarian cancer tissue arrays were used for immunohistochemistry staining. Results: KIF20A is a biomarker of poor prognosis among the kinesin genes. It promotes ovarian cancer cell growth in vitro and in vivo. Ginsenoside Rg3 can suppress the transcription of KIF20A. GST pull-down and co-immunoprecipitation (IP) assays confirmed that KIF20A physically interacts with BTRC (β-TrCP1), a substrate recognition subunit for SCFβ-TrCP E3 ubiquitin ligase. In vitro ubiquitination and cycloheximide (CHX) chase assays showed that via interacting with BTRC, KIF20A reduces BTRC-mediated CDC25A poly-ubiquitination and enhances its stability. Ginsenoside Rg3 treatment partly abrogates KIF20A overexpression-induced CDC25A upregulation. Conclusion: This study revealed a novel anti-tumor mechanism of ginsenoside Rg3. It can inhibit KIF20A transcription and promote CDC25A proteasomal degradation in epithelial ovarian cancer.

Development of a Family Pattern Appraisal to Guide a Rogerian Nursing Practice (Rogers 이론에 근거한 가족양상 사정지침개발)

  • 이광옥;한영란;김희정
    • Journal of Korean Academy of Nursing
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    • v.25 no.4
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    • pp.751-773
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    • 1995
  • We, clinical nurse specialists practising and guiding student practice in a Community health nursing clinic, wanted to develop a family pattern appraisal consistent with Rogers' conceptual system, the nursing model guiding our practice. We use Rogers' model because it is harmonious with the traditional Korean view of the one human, natural and cosmic world. The purpose of our research was to contribute to science - based nursing practice, not only, one helpful model, but also a model of how to use, in guiding practice, a conceptual system which reflects nurse practitioners' philosophy of nursing, is intellectually satisfying, and enriches meaning in daily nursing life. The research objectives were to review the literature on Rogers' model and analyse it according to Kim's five - level analytical framework, to explore Rogers' definition of family, to review appraisals based on Rogers' model, and to develop a family appraisal which is culturally appropriate for use in our community. This work including the use of the appraisal and its refinement with families in our practice which was done during 1994 and 1995, in Seoul, in the Capital of the Republic of Korea. At the highest level of analysis, Rogers conceptual system emphasizes acausality and multidimentional meaning ; the world view is characterized by process, movement and wholeness. The epistemology Is one of holism and the knowledge base includes all forms of experience, from sensory to mystical, objective, and subjective. At the metaparadigm level, nursing focuses on the unitary human being and the environment. At the level of nursing philosophy, the model identifies human being, nursing, nurse, and illness and health. At the paradigm level the model assumes the irriducibility of the human to parts, noncausality and continual change. Rogers' practice methodology consists of pattern manifestation appraisal and deliberative mutual patterning. Under-standing patterns and patterning of people is the key to helping them achieve their potential. At the theory level, the basic assumptions, key concepts, and homeodynamic principles were identified. Rogers states the family energy field is an undividable, four-dimensional negentropic energy field which is in a larger envircinmental field show-ing such characteristics as cannot be predicted by knowledge of individual family members. Based on the word of Rogers scholars, we chose Rogers' correlates of patterning to understand the family unit as a whole-frequency, rhythms, motion, time perception, sleeping-waking beyond waking, pragmatic -imaginative-visionary to develop the appraisal. We, also used some of Barrel's (1988) criteria including interpersonal network and professional health care access and use, and Cordon's (1982) criteria including self perception - self concept modified to fit the family. Our family Pattern appraisal included 1. Influencirg data, 2. Professional health care access and use, 3. Family self perception-self concept, 4. Family interpersonal network, 5. Sleep-wake-be-yond waking, 6. Pragmatic-imaginary-visionary, 7. Family frequency and rhythm, 8. Family motion, 9. Family time perception. The appraisal was used with four families and modified to eliminate overlap and to make it possible for the family member to express themselves more easily. We plan to gain more experience with the appraisal toward further development of the tool.

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Identity-Based Secure Many-to-Many Multicast in Wireless Mesh Networks (무선 메쉬 네트워크에서의 아이디 기반 프록시 암호화를 이용한 안전한 다대다 멀티캐스트 기법)

  • Hur, Jun-Beom;Yoon, Hyun-Soo
    • Journal of KIISE:Information Networking
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    • v.37 no.1
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    • pp.72-83
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    • 2010
  • Group communication in a wireless mesh network is complicated due to dynamic intermediate mesh points, access control for communications between different administrative domains, and the absence of a centralized network controller. Especially, many-to-many multicasting in a dynamic mesh network can be modeled by a decentralized framework where several subgroup managers control their members independently and coordinate the inter-subgroup communication. In this study, we propose a topology-matching decentralized group key management scheme that allows service providers to update and deliver their group keys to valid members even if the members are located in other network domains. The group keys of multicast services are delivered in a distributed manner using the identity-based encryption scheme. Identity-based encryption facilitates the dynamic changes of the intermediate relaying nodes as well as the group members efficiently. The analysis result indicates that the proposed scheme has the advantages of low rekeying cost and storage overhead for a member and a data relaying node in many-to-many multicast environment. The proposed scheme is best suited to the settings of a large-scale dynamic mesh network where there is no central network controller and lots of service providers control the access to their group communications independently.

Seismic behavior of K-type eccentrically braced frames with high strength steel based on PBSD method

  • Li, Shen;Wang, Chao-yu;Li, Xiao-lei;Jian, Zheng;Tian, Jian-bo
    • Earthquakes and Structures
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    • v.15 no.6
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    • pp.667-685
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    • 2018
  • In eccentrically braced steel frames (EBFs), the links are fuse members which enter inelastic phase before other structure members and dissipate the seismic energy. Based on the force-based seismic design method, damages and plastic deformations are limited to the links, and the main structure members are required tremendous sizes to ensure elastic with limited or no damage. Force-based seismic design method is very common and is found in most design codes, it is unable to determine the inelastic response of the structure and the damages of the members. Nowadays, methods of seismic design are emphasizing more on performance-based seismic design concept to have a more realistic assessment of the inelastic response of the structure. Links use ordinary steel Q345 (the nominal yielding strength $f_y{\geq}345MPa$) while other members use high strength steel (Q460 $f_y{\geq}460MPa$ or Q690 $f_y{\geq}690MPa$) in eccentrically braced frames with high strength steel combination (HSS-EBFs). The application of high strength steels brings out many advantages, including higher safety ensured by higher strength in elastic state, better economy which results from the smaller member size and structural weight as well as the corresponding welding work, and most importantly, the application of high strength steel in seismic fortification zone, which is helpful to popularize the extensive use of high strength steel. In order to comparison seismic behavior between HSS-EBFs and ordinary EBFs, on the basis of experimental study, four structures with 5, 10, 15 and 20 stories were designed by PBSD method for HSS-EBFs and ordinary EBFs. Nonlinear static and dynamic analysis is applied to all designs. The loading capacity, lateral stiffness, ductility and story drifts and failure mode under rare earthquake of the designs are compared. Analyses results indicated that HSS-EBFs have similar loading capacity with ordinary EBFs while the lateral stiffness and ductility of HSS-EBFs is lower than that of EBFs. HSS-EBFs and ordinary EBFs designed by PBSD method have the similar failure mode and story drift distribution under rare earthquake, the steel weight of HSS-EBFs is 10%-15% lower than ordinary EBFs resulting in good economic efficiency.

The Planning of Elementary Multicultural Education Programs to Enhance Self-esteem (자아존중감 증진을 위한 초등 다문화교육 프로그램 구안)

  • Jang, Seong-Min;Park, Jin-Hee
    • Journal of Korea Entertainment Industry Association
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    • v.14 no.8
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    • pp.487-499
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    • 2020
  • This study aims to planned Elementary Multicultural Education Program for Promoting Self Esteem. To this end, consider the application force of education and teaching system designed to reorganize the ADDIE Model study was carried out in accordance with the analysis, design, development, process evaluation. To this end, analyzing the between self-esteem and group theory related to them and the social identity theory and key concepts to consider in the context of multicultural education programs for elementary self-esteem enhancement identity, prejudice, cooperation and was composed of equality. Four key concepts are sub-elements of self-esteem individuals, homes, schools, set up a detailed learning objectives in accordance with the social and selecting the learning content and organization, which was composed of a total of 16 class periods. Considering the characteristics and interests of the target students, the teaching-learning method was designed to utilize various methods, including games, quizzes, and discussions, and each class was designed to be developed by organizing them into subjects-learning goals-activities(recognition-exploration-clearing). Since in the three-member expert review, modify the content on the basis of opinions and presented the final program. The program planned by this study, further research is required to verify the effectiveness and utilization in the educational field and expects effective multicultural education.