• 제목/요약/키워드: Multi-joint Mechanism

검색결과 45건 처리시간 0.017초

Seismic performance of RC frame having low strength concrete: Experimental and numerical studies

  • Rizwan, Muhammad;Ahmad, Naveed;Khan, Akhtar Naeem
    • Earthquakes and Structures
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    • 제17권1호
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    • pp.75-89
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    • 2019
  • The paper presents experimental and numerical studies carried out on low-rise RC frames, typically found in developing countries. Shake table tests were conducted on 1:3 reduced scaled two-story RC frames that included a code conforming SMRF model and another non-compliant model. The later was similar to the code conforming model, except, it was prepared in concrete having strength 33% lower than the design specified, which is commonly found in the region. The models were tested on shake table, through multiple excitations, using acceleration time history of 1994 Northridge earthquake, which was linearly scaled for multi-levels excitations in order to study the structures' damage mechanism and measure the structural response. A representative numerical model was prepared in finite element based program SeismoStruct, simulating the observed local damage mechanisms (bar-slip and joint shear hinging), for seismic analysis of RC frames having weaker beam-column joints. A suite of spectrum compatible acceleration records was obtained from PEER for incremental dynamic analysis of considered RC frames. The seismic performance of considered RC frames was quantified in terms of seismic response parameters (seismic response modification, overstrength and displacement amplification factors), for critical comparison.

비선형 해석에 의한 MRS 슬래브 단부 접합부의 모멘트 분포 연구 (Nonlinear Analysis for Negative Moment Distribution of MRS Slab End Joints)

  • 문정호;오영훈;임재형
    • 콘크리트학회논문집
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    • 제23권2호
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    • pp.177-184
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    • 2011
  • 이 연구에서는 PC 구조의 단부를 연속으로 연결한 MRS(multi-ribbed moment resisting slab) 구조에 대한 해석 및 설계법을 제안하고자 하였다. MRS 구조에서는 더블티 부재가 역티보 위에서 부모멘트 철근에 의해서 연속으로 설계되므로, 부모멘트 철근이 좁은 지역에 밀집되는 문제가 발생할 수 있다. 따라서 선형 및 비선형 해석을 통하여 모멘트 분포 메커니즘을 분석하여, 적절한 설계법을 제시하였다. 또한 이 연구와 병행하여 실시한 실험 연구의 결과를 비선형상세 해석을 통하여 분석하였다. 그리고 단부구속효과 및 모멘트 재분배에 관한 연구를 위하여 비선형 골조 해석을 선택하여 변수별 연구를 수행하였다. 해석을 위한 재질 및 단면의 특성은 함께 진행된 실험 연구의 결과로부터 얻어졌으며, 비선형 골조 해석을 위한 소성힌지는 균열 모멘트, 공칭 모멘트, 부재 연성도 등의 값으로 모델링되었다. 선형 및 비선형 해석의 결과로부터 단부 회전 스프링과 부모멘트재분재를 통하여 MRS 구조의 단부 모멘트는 상당한 크기로 감소시킬 수 있음을 알 수 있었다.

기업간 거래에서 정보기술을 활용한 전자적 협력의 범위와 선행요인에 관한 연구 (A Study on the Scope and Determinants of Electronic Collaboration based on IT in Interorganizational Relationships)

  • 최수정
    • Journal of Information Technology Applications and Management
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    • 제15권4호
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    • pp.159-188
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    • 2008
  • This study suggests strategies which can enable to creation of new opportunities of competitive advantages while operating a long lasting and consistent business with major trading partners, based on interorganizational information systems (IOISs) specially established and installed for interorganizational transactions. Nowadays, IOISs based mechanism having been widely expanded as a conventional business infrastructure for the interorganizational transactions and/or exchanges, it is customary difficult to obtain any strongly sound advantage over the competitors who have adopted even the simplest deployment of the IOIS mechanisms. In this connection, this study intends to investigate the interorganizational collaborative activities conducted by under the auspicious of IOISs, focused on the prospect of the exploitation of IOISs rather than the implementation of the IOISs. In this study, we, firstly, suggest the concept of Electronic Collaboration which can be defined by the collaborative activities conducted by IOISs, compared to the ones conducted on off-line. In addition, we suggest the Electronic Collaboration as a multi-dimensional concept, constituted by three sub-constructs, the Electronic Information Sharing (EIS), the Electronic Joint Activity (EJA), and the construction of the Electronic Relational Knowledge Store (ERKS). Secondly, we empirically verify the effects of relational and environmental determinants on the Electronic Collaboration. In this study, the relational determinants relate to the variables created in interorganizational relationship like Trust, Influence, Relational Specific Asset-asset invested for the transaction-, and Continuity of the relationship. On the other hand, the environmental determinants relate to the variables surrounding the relationship which are difficult to control. We consider Product Complexity, Technological Uncertainty, and Market Variability as the domain of the environmental determinants. To test our hypotheses, we conducted both paper-based survey and online-based survey. After refining the data with missing responses, a total of 150 data was used for analysis. The results were as follows : Firstly, it is statistically significant that the Electronic Collaboration is composed of EIS, EJA, and ERKS. In particular, the results imply that the firms are able to accumulate relational knowledge base as well as to exchange information or knowledge, and to conduct joint activities through effort to further expand the Electronic Collaboration. Secondly, we have verified the individual effects of the relational and the environmental determinants on the Electronic Collaboration. Product Complexity has been revealed as the most influential variable affecting the Electronic Collaboration. Next, Interorganizational Trust and Technological Uncertainty, in that order, have been seen to have significant effects on the Electronic Collaboration. In other words, when products or services seem to be difficult to standardize, and the core technologies seem to rapidly change, the need for the Electronic Collaboration increase. In addition, the observation dictates that the interorganizational trust turns out to be a critical variable in building a relationship and in seeking further collaboration. The results, further, illustrate that the environmental determinants are relatively more effective than the relational determinants, which is not consistent with a few prior researches relational determinants emphasized. It is because this study doesn't consider the size of the firm. A few researchers have given an emphasis on the relational determinants like trust and influence, especially from the perspective of small firms in interorganizational relationship. However, in our study, where all the sizes of the firms are contained, electronic collaboration is considerably affected by the environmental determinants.

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절삭유 분사위치에 따른 STS316L의 밀링가공 특성 개선 (Improvement of STS316L Milling Characteristics According to Coolant Spray Position)

  • 김수환;박민수
    • 대한기계학회논문집A
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    • 제41권5호
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    • pp.427-433
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    • 2017
  • 고강도 재료나 열전도성이 낮은 재료의 밀링 가공시 가공 부위에서 발생하는 높은 마찰열로 인해 공구 파손 등이 심각하게 발생할 수 있으므로 절삭유 공급이 매우 중요하다. 기존의 절삭유 공급 방식은 수동식 관절 구조를 활용한 방법으로 과도한 양을 분사함에도 불구하고 효과적인 결과를 얻기 힘들었다. 또한, 작업 중 비산으로 인해 작업장 환경에도 큰 악영향을 미쳤다. 이에 본 연구에서는 자동으로 분사 위치 조절이 가능한 장치에 기반하여 절삭유 분사위치에 따른 STS316L 의 밀링가공 특성을 분석하였다. 그 결과, 절삭유 공급 위치 변화에 따라 공구 마모와 표면 거칠기 변화가 관찰되었으며 이를 통해 제작된 장치의 효용성을 보였다.

Estimating the Effects of Multipath Selection on Concurrent Multipath Transfer

  • Wang, Jingyu;Liao, Jianxin;Wang, Jing;Li, Tonghong;Qi, Qi
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제8권4호
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    • pp.1406-1423
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    • 2014
  • Multi-mode device which combines multiple access technologies into a device will offer more cost-effective solution than a sole access implementation. Its concurrent multipath transfer (CMT) technology can transmit media flows over multiple end-to-end paths simultaneously, which is essential to select at least two paths from all available paths. At real networks, different paths are likely to overlap each other and even share bottleneck, which can weaken the path diversity gained through CMT. Spurred by this observation, it is necessary to select multiple independent paths as much as possible to avoid underlying shared bottleneck between topologically joint paths. Recent research in this context has shown that different paths with shared bottleneck can weaken the path diversity gained through CMT. In our earlier work, a grouping-based multipath selection (GMS) mechanism is introduced and developed. However, how to estimating the selection is still to be resolved. In this paper, we firstly introduce a Selection Correctness Index (SCI) to evaluate the correctness of selection results in actual CMT experiment. Therefore, this metric is helpful to discuss and validate the accuracy of the output paths. From extensive experiments with a realized prototype, the proposed scheme provides better evaluation tool and criterion in various network conditions.