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        검색결과 184

        41.
        2016.04 구독 인증기관·개인회원 무료
        The clamping of torque shear high strength bolt is induced when the pin-tail is broken. However the tension forces induced shank of the bolt do not be known by now. This study focused to develop a quantitative method to identify the induced tension by analyzing the electric energy of which electric torque wrench was applied to high strength bolt at the break of pin tail. Based on this co-relation between tension and accumulated current, the regressive analysis was derived. The error rate between tension and accumulated current was 2.24%.
        42.
        2016.04 구독 인증기관·개인회원 무료
        In this paper, we study the calculation for the damage area of the tension specimens using image processing techniques. This study was able to calculate the area of the damage region on the basis of original image. Generally, to extract the area in the original image, we have to use opening operation, close operation, the Hit-or-Miss operation and bottom hat filter, top hat filter, etc. In particular, to extract the area of the composite specimen discussed in this study, we have to use the combination of the operations and filters because it is non-isotropic material, or should develop a new algorithm based on it.
        43.
        2016.04 구독 인증기관·개인회원 무료
        Axial force of the bolt is very important for structural stability. To obtain stability of the structure, axial force of the bolt should satisfy the specification and be maintained over the time. Hence, It is important to the axial force of the bolt is measured and it manages. However, measuring of the axial force using sensors is very expensive. Torque method using frequently in the field is difficult to confirm accurately by the torque coefficient change. In this study, measuring of axial force using elastic force of the spring washer was studied. First, the relational formula is drawn about the pressure in which the spring washer model changes to the annular of the plane state. According to the axial force of the bolt, the necessity height of the spring washer is presented and the finite-element analysis model is recommended. The analysis model research, generally, the axial force of high strength bolt is confirmed. It expands to confirmation of the large caliber bolt.
        44.
        2016.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Until recently, almost all ETFE film structures that have been erected is the cushion type because there are problems at lower allowable strength under elastic range and viscosity behaviour such as creep and relaxation of ETFE films under long-term stresses. But the number of tension type structures is currently increasing. This paper proposes the stretch fabrication of ETFE film to verify the applicability of ETFE films to tensile membrane structures. First of all, to investigate the possibility of application on tensile membrane structures, the stretch fabrication test is carried out, and it is verified that it is possible to increase the yield strength of the film membrane structures. After simulating the experiment also carries out an analytical investigation, and the effectiveness of the elasto-plastic analysis considering the viscous behavior of the film is investigated. Finally, post-aging tension measurement is conducted at the experimental facilities, and the viscosity behavior resulting from relaxation is investigated with respect to tensile membrane structures.
        4,000원
        45.
        2015.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        이 연구에서는 FBG센서가 내장된 강연선을 포스트텐션 UHPC 교량(길이 11.0m, 폭 5.0m, 높이 0.6m)에 적용하고 약 1년간의 긴장력 장기모니터링 결과를 정리하였다. 그리고 초기 도입 긴장력과 차량재하시험을 통하여 콘크리트 내부 강연선의 긴장력 변화를 계측하고 계측결과에 대한 분석을 수행하였다. 연구결과, 이 연구에서 제안하는 콘크리트 내부 긴장력 측정방법이 공영 중인 교량에서 외력으로 인한 콘크리트 내부의 작은 프리스트레스 변화를 효과적으로 측정할 수 있음을 알 수 있었다. 아울러 장기 계측결과를 이용하여 응력변화에 의한 유효변형률을 정확하게 얻기 위해서는 온도보정에 사용되는 열팽창계수의 선택이 매우 중요함을 알 수 있었다.
        4,000원
        47.
        2015.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To prevent cargo accidents by repeated loads, a continuous monitoring for securing rope or additional safety measures are needed, but most of prevention measures have been conducted only by operator's own experience not a quantitative assessment. Hence, the Load-Displacement curve and approximation formula of securing rope were drawn in this research for a quantitative assessment and simplified measurement on a tension of securing rope using a tensiometer. Moreover, a com parison was conducted between m easuring tension and calculated tension on securing rope with portable tensiometer, 'Load-Displacement' approximation formula. The calculated tension of securing rope is obtained 153.3kfg using the formula and that result has not much difference with initial tension 150.0kgf. Lastly, an analysis of the characteristics of various ropes was suggested to enhance the reliability about quantitative assessment of securing rope's tension through further research.
        4,000원
        48.
        2015.05 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In-situ neutron diffraction has been employed to examine the effect of strain path on lattice strain evolution during monotonic and cyclic tension in an extruded Mg-8.5wt.%Al alloy. In the cyclic tension test, the maximum applied stress increased with cycle number. Lattice strain data were acquired for three grain orientations, characterized by the plane normal to the stress axis. The lattice strain in the hard {10.0} orientation, which is unfavorably oriented for both basal slip and {10.2} extension twinning, evolved linearly throughout both tests during loading and unloading. The {00.2} orientation exhibited significant relaxation associated with {10.2} extension twinning. Coupled with a linear lattice strain unloading behavior, this relaxation led to increasingly compressive residual strains in the {00.2} orientation with increasing cycle number. The {10.1} orientation is favorably oriented for basal slip, and thus showed a soft grain behavior. Microyielding occurred in the monotonic tension test and in all cycles of the cyclic test at an applied stress of ~50 MPa, indicating that strain hardening in this orientation was not completely stable from one cycle to the next. The lattice strain unloading behavior was linear in the {10.1} orientation, leading to a compressive residual strain after every cycle, which, however, did not increase systematically from one cycle to the next as in the {00.2} orientation.
        4,000원
        49.
        2015.04 구독 인증기관·개인회원 무료
        These days, the Composite Slabs with Deep deck plate was commonly used in domestic construction site, and, the application of the Slim Floor system was increased from the Enlargement and High-rise Building. But, Slim Floor system using the deep deck was shown safety problem caused by the deflection and local buckling in construction phase when used to more than 6m. Therefore, for solving the problem, the installation of the shores is essential. This study is realize the long span slab without shores from control the deflection through applied the pre-tensioning elements in cap deck. In addition, by applying the pre-tensioning member as the tensile member of the Cap Deck composite slab, the pre-tensioning member for the shores tries to be used as the structural member. Accordingly, to determine the flexural performance of the Cap deck composite slab through the pre-tensioning force in tensile member, and, the composite effect of the cap deck composite slab by the experiments.
        50.
        2015.04 구독 인증기관·개인회원 무료
        In this paper, we study the calculation for the fracture area of the tension specimens using digital image processing techniques. This study was able to calculate the area of the fracture region on the basis of improved image. To extract the area in the original image, we have to use opening operation, close operation, the Hit-or-Miss operation and Bottom hat filter, Top hat filter, etc. In particular, to extract the area of the composite specimen discussed in this study, we have to use the combination of the operations and filters because it is non-isotropic material, or should develop a new algorithm based on it.
        51.
        2014.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Porcelain surge arrestor is very vulnerable to earthquake but there is very few information on its dynamic characteristics which are necessary to the seismic design. Therefore, the dynamic characteristics of the porcelain surge arrestor are evaluated considering the variation of its cable tension and stiffness by shaking table test. The test results show that the first natural frequencies are 5.3 Hz and 5.2 Hz in the horizontal x- and y-axis directions, respectively, and higher than 30 Hz in the vertical z-axis direction, respectively. The installation of cable on the surge arrestor reduces the horizontal natural frequencies due to the constraint effect of the cable but cable tension has no effect on the natural frequency. Also, the natural frequency is proportional to the stiffness of the surge arrestor. This test result will be used for the seismic design and seismic capacity assessment of domestic substations and contribute to the stability of the electric power supply under earthquake event.
        4,000원
        52.
        2014.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The difference of mooring tension by type of buoy was investigated in the circulating water channel and the wave tank for deducting the most stable buoy from the current and the wave condition. 5 types of buoy made up of short cylinder laid vertically (CL-V), short cylinder laid horizontally (CL-H), capsule (CS), sphere (SP) and long cylinder (CL-L) were used for experiments. A mooring line and a weight were connected with each buoy. A tensile gauge was installed between a mooring line and a weight. All buoy’s mooring tension was measured at the same time for the wave test with periods of 1.5~3.0 sec and wave heights of 0.1~0.3 m, and the current test with flow speeds of 0.2~1.0 m/sec. As a result, the order of tension value in the wave test was CL-H > CL-V > SP > CS > CL-L. In the current test CL-V and CL-H were recorded in the largest tension value, whereas SP has the smallest tension value. So it seems that SP buoy is the most effective in the location affected by fast current. CS is predicted to be suitable for a location that influence of wave is important more than that of current if practical use in the field is considered. And it was found that the difference of mooring tension among buoys in wave is related to the product of the cross sectional area and the drag coefficient for the buoy’s bottom side in high wave height. The factor for the current condition was not found. But it was supposed to be related to complex factors like a dimension and a shape by buoy’s posture to flow.
        4,200원
        53.
        2014.07 구독 인증기관 무료, 개인회원 유료
        A well-known dilemma in strategic marketing is whether a firm can be simultaneously both efficient in its existing business and innovative in creating new business (Atuahene-Gima 2005; Christensen 1997). Beleaguered companies such as AOL, Kmart, Motorola, Nokia, Polaroid, and Sears are examples that were once highly efficient in serving customers, but partly due to that efficiency in their existing business, paradoxically failed to introduce innovations. The potential tension “between innovation and efficiency—is one that’s bedeviling CEOs everywhere” (Hindo 2007). Two questions regarding the efficiency–innovation tradeoffs are especially intriguing to researchers and managers alike. First, to what extent are such tradeoffs driven by efficient firms’ lack of eagerness or willingness to innovate in the first place, or lack of ability to innovate and promote innovations? Second, can certain strategic marketing factors mitigate the tension of such tradeoffs? Indeed, anecdotal evidence indicates that not all firms that are efficient in their current business (e.g., Charles Schwab, Capital One) lack innovative thrust. In fact, efficient firms may actually be eager to innovate: Nokia, for instance, originally innovated an online “app store” service as well as touchscreen smartphones and Internet tablets in the 1990s and 2000s, much earlier than Apple (Ben-Aaron 2009; MobileGazzette 2008). Similarly, Polaroid was originally a pioneer in developing digital cameras and imaging services in the 1980s (Tripsas and Gavetti 2000). The eventual failures of Nokia’s and Polaroid’s innovation efforts, thus, do not seem to be due to their lack of eagerness to innovate, but perhaps the inability to manage the efficiency–innovation tension. In contrast, other companies seem to be able to manage this tension. For instance, in financial services, Charles Schwab is often commended both for its efficiency and its innovativeness, and the firm itself feels the “need to invest in innovation to maintain a competitive edge” (Gilson 2012). Against this backdrop, we focus on two questions: (1) What exactly are the tradeoffs and tensions between a firm’s existing efficiency, innovativeness in its new offerings, and new offering performance? And (2) how can strategic marketing assets such as customer base and advertising intensity mitigate the tradeoffs? Should such assets help to alleviate the inherent tension, they would give executives tools to pursue both efficiency and innovation at the same time and succeed with their new innovative offerings. Empirically, we focus on the service sector, whereby the actual technical development of innovations is not very costly in tangible financial terms (Crawford and di Benedetto 2008; Droege et al. 2009; Thomke 2003)―making the intangible firm capabilities most likely determinants of (innovation) performance rather than tangible resources (cf. Vorhies, Morgan, and Autry 2009). Therewith, we examine our research questions with a comprehensive census dataset of all new service introductions (n≈500) in one national market: The Finnish mutual funds industry (1997–2010). The sector of financial services is especially relevant for the efficiency–innovation tradeoffs because in this sector, many firms are compelled to engage in both efficient operations and effective (financial) innovations. Our empirical focus on all firms in one market precisely identifies and measures the efficiency levels of all competing firms, relative to the best-performing competitors, as well as innovativeness (earliness) in introducing new services compared to all rivals. For a marketing perspective, we focus on firms’ existing customer-perceived service efficiency (over the entire portfolio of existing services, i.e., funds)—defined through the ratio of output value that customers obtain from the firms’ current services to the (customer) cost inputs. We also carefully delineate between (a) innovativeness of a new service introduction and (b) its performance. Doing so can reveal the potentially contradictory effects of existing efficiency on new service innovativeness (willingness to innovate) vis-à-vis new service performance (ability to make innovations succeed). As our key results, we firstly identify and explicate the baseline efficiency–innovation tradeoffs. Specifically, our results suggest that while existing service efficiency increases the innovativeness of new services introduced by the firm, it simultaneously (1) leads to decreased business performance for the new services introduced and (2) diminishes the positive influence of innovativeness on performance. In sum, these findings imply that on the baseline, highly efficient service firms may be too eager to innovate, considering the sub-par performance they are likely to receive for those innovations. Secondly, our results reveal two strategic marketing factors, which have the potential to mitigate the tradeoffs. We find that the firm’s (a) focused customer base and (b) high advertising intensity can nullify the negative effect of existing service efficiency on innovativeness and the negative moderating effect of efficiency on the innovativeness–performance link.
        5,800원
        54.
        2014.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper presents the theoretical analysis for the flow driven by surface tension and gravity force in an inclined circular tube. The present study introduces detailed mathematical procedures for Casson viscosity model. The equations of velocity distribution and flow rate are developed to describe the displacement of a non-Newtonian fluid that continuously flew into a circular tube by surface tension. The equation of modified volumetric flow shows the complicated form of (10) due to yield stress term, and the equation of velocity distribution which includes the yield stress and inclination angle of circular tube is composed of terms of r and rc as form of (14).
        4,000원
        55.
        2014.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        강도 한계상태 설계에서는 균열이 일어난 이후 철근콘크리트 부재의 인장영역에서 철근이 모든 인장력을 부담하는 것으로 가정한다. 그러나 균열 사이의 콘크리트가 실제 콘크리트 부재에서는 특히 사용하중 수준에서의 어느 정도의 인장 응력을 견디는데, 일조 하는 것으로 보고 있다. 이러한 효과를 Tension stiffening 효과라 한다. 본 연구에서는 Tension stiffening 모델과 고강도 철근 콘크리트 보의 휨 실험결과의 비교를 통해 해석모델의 유효성을 평가 하고자 한다. 이를 통해 선정 된 6가지의 Tension stiffening 모델과 실험에 의한 모멘트-곡률, 하중-처짐등을 관계를 평가하였다. 실험결과 설계기준에서는 ACI 318이 Tension stiffening 모델에서는 Owen & Damjanic이 실험 값과 가장 적은 오차율을 보이며 높은 신뢰도를 보였다.
        4,000원
        56.
        2013.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 토성에 따른 물의 이용효율을 높이면서 재배 작물의 생산성을 최대화하기 위한 효율적인 자동관개 로직을 개발하고자, 수분장력값을 관수 개시점으로 하여 물 공급 유지와 멈춤을 간헐적으로 수행하는 펄스형 관개방식과 측정한 수분장력값을 이용하여 토양수분량을 예측해 재배작물에 적합한 물량을 추가 투입하는 필요물량계산 관수방식을 적용하여 토성이 다른 실험베드에서 2년간 토마토 작물을 재배하면서 토양수분 함량과 장력의 변화를 측정비교하였다. 물공급 30초와 멈춤 30분 및 15분 조건을 이용한 펄스형 관수방식과 필요물 량계산 방식에서 얻어진 수분장력값은 목표한 −20kPa 조건에 비해 각각 −42~−8kPa, −20~−10kPa로 나타나 필요물량 계산방식이 균일한 수분장력을 유지하는 측면에서는 유리하였으나 토양수분상태는 상대적으로 습하였다. 공시 토성 모두에서 수분함량은 수분장력에 비해 시간 반응이 빠르면서 물공급에 따라 비례적으로 증가하는 경향이 뚜렷하였다. 수분변화 값은 펄스형 관수와 필요물 량계산 관수방식의 경우 사양토 기준으로 각각 17~ 24%, 19~31%로서 펄스형 관수방식이 수분변화 값이 작으면서 시간에 따라 안정적인 값을 유지한 것으로 나타났는데 이는 물공급에 따른 수분함량의 시간변화가 수분 장력에 비해 뚜렷하게 빠름과 관계가 있는 것으로 판단하였다. 이러한 결과로부터 펄스형 관수방식은 수분함량 값을 이용하여 수분을 조절하는 것이 유리함을 의미한다.
        4,000원
        60.
        2013.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper presents the theoretical analysis for the flow driven by surface tension and gravity force in an inclined circular tube. The governing equation is developed to describe the displacement of a Newtonian fluid that continuously flew into a circular tube by surface tension, which represents a second-order, nonlinear, nonhomogeneous and ordinary differencial form. It was found that the theoretical predictions of the governing equation were excellent agreement with the unsteady state solutions for horizontal tube and the results of force balance equation for steady state.
        4,000원
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