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Seismic progressive collapse mitigation of buildings using cylindrical friction damper

  • Mirtaheri, Masoud;Omidi, Zobeydeh;Salkhordeh, Mojtaba;Mirzaeefard, Hamid
    • Earthquakes and Structures
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    • v.20 no.1
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    • pp.1-12
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    • 2021
  • The occurrence of progressive collapse induced by the removal of the vertical load-bearing element in the structure, because of fire or earthquake, has been a significant challenge between structural engineers. Progressive collapse is defined as the complete failure or failure of a part of the structure, initiating with a local rupture in a part of the building and can threaten the stability of the structure. In the current study, the behavior of the structures equipped with a cylindrical friction damper, when the vertical load-bearing elements are eliminated, is considered in two cases: 1-The load-bearing element is removed under the gravity load, and 2-The load-bearing element is removed due to the earthquake lateral forces. In order to obtain a generalized result in the seismic case, 22 pair motions presented in FEMA p 695 are applied to the structures. The study has been conducted using the vertical push down analysis for the case (1), and the nonlinear time-history analysis for the second case using OpenSEES software for 5,10, and 15-story steel frames. Results indicate that, in the first case, the load coefficient, and accordingly the strength of the structure equipped with cylindrical friction dampers are increased considerably. Furthermore, the results from the second case demonstrate that the displacements, and consequently the forces imposed to the structure in the buildings equipped with the cylindrical friction damper substantially was reduced. An optimum slip load is defined in the friction dampers, which permits the damper to start its frictional damping from this threshold load. Therefore, the optimum slip load of the damper is calculated and discussed for both cases.

A Borderland between Green and Brown Landscapes: An Ecocritical Road to Urban Nature Writing (녹색과 갈색의 경계지대 - 미국 도시근교자연문학과 생태비평의 영역확장)

  • Shin, Doo-ho
    • Journal of English Language & Literature
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    • v.54 no.1
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    • pp.31-60
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    • 2008
  • As a way to situate environmental literary study, urban nature recently seems to have become an increasingly important part of ecocritical studies. Considering the recent deprecation on the alleged ecocriticism's ecocentric position, this move looks promising. However, a scrutable review of recent publications of ecocritical studies reveals a contradicting result that an ecocritical approach to urban nature not only lacks substance but also makes too much of the cultural and political issues of 'environmental justice' in which the traditional value and beauty of nature is totally sacrificed and neglected for its political purpose. Under the current circumstance that the environmental crisis threatens all landscapes of wild, rural, and urban, ecocriticism needs to put together "green" landscapes of wildness and "brown" landscapes of urban environment. The interdependence between outback and urban landscapes is best observed in suburban areas in which both landscapes coexist and merge. Provided with due learning and attention of nonhuman environment in their backyard, suburban residents have privilege of both appreciating nature's beauty and value of its own, on the one hand, and acutely reckoning urban environmental concerns related to their health, safety, and sustenance, on the other, in their own home grounds. The post-1980s in the United States has witnessed the emerging voices of suburban nature writings that speak for both green and brown landscapes, which have escaped from ecocritical attention. Among the suburban nature writings, those of Michael Pollan and Thomas Mitchell well illustrate how the green and brown landscapes are interwoven and, accordingly, how environmental awareness of both landscapes can start in suburban 'home.' Ecocriticism's validation as relevant studies of literature and environment may depend on these suburban nature writings which demonstrate an 'ancient-future' ethic of "home" based environmentalism.

A Survey on the Status and the Importance of Initial History Taking in Dental Clinics in S Area

  • Lim, Do-Seon;Jung, Im-Hee;Im, Ae-Jung;Lim, Hee-Jung
    • Journal of dental hygiene science
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    • v.20 no.4
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    • pp.261-268
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    • 2020
  • Background: A comprehensive history taking at the first visit could be an important start of treatment. This study investigated the current status of the initial history taking for dental patients in S area, and the implementation and importance of the initial history taking process. Based on this, we intend to provide basic data for the development of organized and standardized questionnaires in dental clinics. Methods: In April 2019, 303 dental clinics in S area were targeted and special dental clinics (orthodontics, children, and disabled) were excluded. The questionnaire consisted of 29 items, including general characteristics, systemic disease history, dental history, oral health behaviors, and the data were obtained through self-administered questionnaire. Results: Initial history taking was mostly implemented using oral and questionnaire at the time of the first visit. Systemic disease history, dental history, and oral health behaviors differed in the work experience of the dental clinic staff. As a result of analyzing the importance according to implementation, there were significant differences in all questions except drug-related items. The importance of the questionnaire was highly recognized, but the reason it was not actually implemented was because of existing the questionnaire in the clinic and lack of time. Conclusion: Considering that the initial history taking implementation rate showed low, it is necessary to develop standardize a practical questionnaire and interview skills for dental clinics in the future. In addition, training programs should be provided to dental staff that can recognize the importance of initial history taking questionnaires and contribute to active implementation.

Battery State-of-Charge Estimation Using ANN and ANFIS for Photovoltaic System

  • Cho, Tae-Hyun;Hwang, Hye-Rin;Lee, Jong-Hyun;Lee, In-Soo
    • The Journal of Korean Institute of Information Technology
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    • v.18 no.5
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    • pp.55-64
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    • 2020
  • Estimating the state of charge (SOC) of a battery is essential for increasing the stability and reliability of a photovoltaic system. In this study, battery SOC estimation methods were proposed using artificial neural networks (ANNs) with gradient descent (GD), Levenberg-Marquardt (LM), and scaled conjugate gradient (SCG), and an adaptive neuro-fuzzy inference system (ANFIS). The charge start voltage and the integrated charge current were used as input data and the SOC was used as output data. Four models (ANN-GD, ANN-LM, ANN-SCG, and ANFIS) were implemented for battery SOC estimation and compared using MATLAB. The experimental results revealed that battery SOC estimation using the ANFIS model had both the highest accuracy and highest convergence speed.

Study on Measures to Activate Technology Startup through National R&D Support Project

  • YUN, Jeong-Keun
    • The Journal of Economics, Marketing and Management
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    • v.8 no.4
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    • pp.1-12
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    • 2020
  • Purpose- The purpose of this study is to increase the effect of public technology transfer through government R&D support to secure the competitiveness of public technology startups. The government's R&D budget in 2019 is over 20 trillion won, and there is a legitimate need to increase the performance of technology startups through such R&D results. Research design, data, and methodology- In this paper, we comprehensively analyzed the current status of public research institutes and R&D support projects suitable for founders and analyzed and presented cases of follow-up research conducted by the Institute of Science and Technology Jobs to analyze actual performance cases of R&D support institutes. Results- In this conclusion, a developmental model of public technology entrepreneurship was proposed to increase the performance of public technology commercialization with the scalability of research institutions. In order to create a public technology information system between consumers and suppliers, a Steinweiss-type technology commercialization model for public technology commercialization, and a job-creating enterprise-type linkage R&D support business model were presented to create the results of R&D support organizations. Conclusions- Through the results of this study, it is meaningful to analyze the performance cases of technology commercialization of R&D support institutions, which have not been studied so far, to build competitiveness of research institutions and to present a growth model for the spread of technology startups. This study has implications in terms of suggesting a way to build competitiveness in technology commercialization between market demanders and suppliers by linking existing public technology startups, which deviated from the simple commercialization support system, with job creation by expanding the R&D support system.

Exploring the Motivational Use of Special Libraries from a User's ARCS Perspective (이용자의 ARCS 관점에서 본 전문도서관 동기적 이용 탐색)

  • Na, Kyoungsik;Jeong, Yongsun
    • Journal of the Korean Society for information Management
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    • v.39 no.2
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    • pp.35-60
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    • 2022
  • This study reports on the motivational use of special libraries from a user's perspective that investigated four motivational components: attention, relevance, confidence, and satisfaction (ARCS) of the library users. Even though special libraries received relatively little attention compared to public libraries, special libraries could fill the niche of public libraries for the special and specific needs of the community in the current library environments in South Korea. Qualitative data were collected through individual interviews and forty people participated in the project. The findings of this study show the four themes (ARCS) that users need motivation as a way to start using a special library, thereby staying focused and revisiting the library. It is possible that the ARCS model will contribute to the implementation, application, and practice of both special libraries and their services in the library environment. The results are expected to expand our knowledge on the motivational ARCS use of special libraries and to serve as basic data when designing motivational strategies and plans of the systems for special libraries.

A Comparative Study on the Right to Know Industrial Health Information among Workers (노동자의 산업보건정보에 대한 알 권리의 비교법적 고찰)

  • Jung, Jin-Woo
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.32 no.2
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    • pp.89-101
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    • 2022
  • Objectives: By comparing and examining how important issues concerning industrial health information for workers are viewed in other advanced countries, it is intended to ascertain problems in the approach found in Korean legislation and obtain legal and policy implications. Methods: The results of a survey were introduced and analyzed through a comparative method for each case after investigating in detail what and how important issues surrounding workers' right to know industrial health information are reflected in the legislation of Germany, the U.S., the U.K., and Japan. Based on the results of this comparative analysis, theoretical and policy implications and legal policy improvement tasks were drawn to strengthen workers' right to industrial health information for each case in Korea. Results: For access to industrial health information, most of the other advanced countries clearly stipulate a right to access for current and past workers and/or their representatives. As a result, workers or their representatives do not need to use the Information Disclosure Act to access exposure records, and there is no debate over the Information Disclosure Act. In other words, industrial health information is focused on ensuring free access to workers or their representatives and is not interested in reporting it to the government. Conclusions: In order to strengthen workers' right to know about industrial health, it is most important to address the legal issues related to this right, which is considered insufficient by comparative law. This should start with a concrete and effective definition of what and how to guarantee workers' rights to industrial health, such as the right to freely access industrial health information, including for retired workers and bereaved families of deceased workers.

The Analysis on the Recyclability of Shenlong Automobile Company in China using SWOT Technique

  • Zhao, Wei;Jung, Heonyong
    • International Journal of Advanced Culture Technology
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    • v.10 no.3
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    • pp.146-155
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    • 2022
  • The purpose of this study is to investigate the recyclability of Shenlong in China using SWOT. The main analysis results are as follows. First, provided that the company's current capacity utilization rate is seriously insufficient, reducing staff is one among the effective ways. Second, Shenlong should open a web store to cater to young people's online shopping behavior, and further expand the brand visibility using national mainstream media and online shopping platforms like Taobao and JingDong to market Dongfeng Peugeot and Dongfeng Citroen on the whole network. Third, under the premise of maintaining the present best-selling models, Shenlong should appropriately reduce the amount of models, adjust the assembly capacity ratio of every model and every displacement in real time per the newest market trends, increase the agility of auto companies' production, and timely meet the wants of domestic consumers. Fourth, dual-brand coordination and channel integration are very necessary, and also the profitability and profitability of dealers are going to be further improved, thereby increasing sales. Fifth, target building new energy leading products of Shenlong, strive to attain the forefront of the industry within the sales of recent energy vehicles within 5 years, and gradually expand new energy vehicle products from passenger vehicles to passenger vehicles and commercial vehicles. Finally, the marketing field of Shenlong Automobile should achieve "three major changes", that is, change from a goal-driven type to a demand-driven type, cancel the bundling of outlet invoicing goals and delivery incentive tiers; start from basic capabilities, and set pragmatic and challenging goals; focus Channels, to realize following the activation of outlets, and single store sales increase.

The Problem of the Quality of the Predecessor Activity on the Time and Cost of the Successor Activity in the Project Schedule - Project Schedule with Resource Constraints - (프로젝트 일정에서 선행활동 품질이 후행활동의 시간과 비용에 미치는 문제 - 자원제약이 존재하는 프로젝트 일정문제 -)

  • Kim, Gab Sik;Bae, Byeong Man;Ahn, Tae Ho
    • Journal of Korean Society for Quality Management
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    • v.50 no.2
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    • pp.265-286
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    • 2022
  • Purpose: The time and cost of a project activity exists in a selected mode and there is a quality level for the selected mode, and the time and cost of the current activity is determined by the quality level of the preceding activity. When an activity is a predecessor activity of an activity, it is characterized as a trade-off problem in which the time and cost of the activity are determined according to the quality level of the activity. Methods: A neighbor search heuristic algorithm obtains a solution by (1) randomly determining the mode, quality level, and assignment order for each activity. (2) get a solution by improving the solution by changing the possible modes and quality levels; (3) to find a solution by improving the solution from the point where it is feasible to advance the start time. Here, Case[1] is a method to find the optimal solution value after repeating (1). Case [2] is a method for finding a solution including (1) and (2). Case [3] refers to a method for finding solutions including (1), (2), and (3). Results: It can be seen that the value of the objective function presented by the algorithm changes depending on how the model of the heuristic algorithm is designed and applied. In other words, it suggests the importance of algorithm design and proves the importance of the quality problem of activities in the project schedule. Conclusion: A study significance of the optimization algorithm and the heuristic algorithm was applied to the effect of the quality of the preceding activity on the duration and cost of itself and the succeeding activity, which was not addressed in the project schedule problem.

Analysis of Construction Company's Bidding Practice under the Lowest Bidding System (최저가낙찰제하에서의 건설업체의 투찰 형태 분석)

  • Lee, Hyungwoo;Chang, Chul-Ki;Kim, Yong-Su
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.6D
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    • pp.975-983
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    • 2006
  • This study analyzed bidding data for construction projects ordered by the Public Procurement Service under the lowest bidding system since 2001 by using statistical technique in terms of construction types, company sizes, bidding prices. This study brings out construction company's bidding practices and problems caused by the current lowest bidding system and suggests the way to mitigate the problems and to improve the lowest bidding system. The analysis shows the problem of winning a bid in abnormally low price under the lowest bidding system, feared at the start, was realized. As bidding practice has polarized with low and high price, the analysis shows that the lowest bid system's market has a high possibility to be distorted by construction companies' bid strategies. To complement the lowest bidding system's problem, the analysis shows that introduction of the bidding system using particulars where bidders estimate construction quantities and unit prices by themselves is needed.